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Sample records for magnetic flux tubes

  1. Color magnetic flux tubes in dense QCD

    SciTech Connect

    Eto, Minoru; Nitta, Muneto

    2009-12-15

    QCD is expected to be in the color-flavor locking phase in high baryon density, which exhibits color superconductivity. The most fundamental topological objects in the color superconductor are non-Abelian vortices which are topologically stable color magnetic flux tubes. We present numerical solutions of the color magnetic flux tube for diverse choices of the coupling constants based on the Ginzburg-Landau Lagrangian. We also analytically study its asymptotic profiles and find that they are different from the case of usual superconductors. We propose the width of color magnetic fluxes and find that it is larger than naive expectation of the Compton wavelength of the massive gluon when the gluon mass is larger than the scalar mass.

  2. MAGNETIC FLUX TUBE INTERCHANGE AT THE HELIOPAUSE

    SciTech Connect

    Florinski, V.

    2015-11-01

    The magnetic field measured by Voyager 1 prior to its heliocliff encounter on 2012.65 showed an unexpectedly complex transition from the primarily azimuthal inner-heliosheath field to the draped interstellar field tilted by some 20° to the nominal azimuthal direction. Most prominent were two regions of enhanced magnetic field strength depleted in energetic charged particles of heliospheric origin. These regions were interpreted as magnetic flux tubes connected to the outer heliosheath that provided a path for the particles to escape. Despite large increases in strength, the field’s direction did not change appreciably at the boundaries of these flux tubes. Rather, the field’s direction changed gradually over several months prior to the heliocliff crossing. It is shown theoretically that the heliopause, as a pressure equilibrium layer, can become unstable to interchange of magnetic fields between the inner and the outer heliosheaths. The curvature of magnetic field lines and the anti-sunward gradient in plasma kinetic pressure provide conditions favorable for an interchange. Magnetic shear between the heliosheath and the interstellar fields reduces the growth rates, but does not fully stabilize the heliopause against perturbations propagating in the latitudinal direction. The instability could create a transition layer permeated by magnetic flux tubes, oriented parallel to each other and alternately connected to the heliosheath or the interstellar regions.

  3. Siphon flows in isolated magnetic flux tubes. 3: The equilibrium path of the flux tube arch

    NASA Technical Reports Server (NTRS)

    Thomas, John H.; Montesinis, Benjamin

    1989-01-01

    The arched equilibrium path of a thin magnetic flux tube in a plane-stratified, nonmagnetic atmosphere is calculated for cases in which the flux tube contains a steady siphon flow. The large scale mechanical equilibrium of the flux tube involves a balance among the magnetic buoyancy force, the net magnetic tension force due to the curvature of the flux tube axis, and the inertial (centrifugal) force due to the siphon flow along curved streamlines. The ends of the flux tube are assumed to be pinned down by some other external force. Both isothermal and adiabatic siphon flows are considered for flux tubes in an isothermal external atmosphere. For the isothermal case, in the absence of a siphon flow the equilibrium path reduces to the static arch calculated by Parker (1975, 1979). The presence of a siphon flow causes the flux tube arch to bend more sharply, so that magnetic tension can overcome the additional straightening effect of the inertial force, and reduces the maximum width of the arch. The curvature of the arch increases as the siphon flow speed increases. For a critical siphon flow, with supercritical flow in the downstream leg, the arch is asymmetric, with greater curvature in the downstream leg of the arch. Adiabatic flow have qualitatively similar effects, except that adiabatic cooling reduces the buoyancy of the flux tube and thus leads to significantly wider arches. In some cases the cooling is strong enough to create negative buoyancy along sections of the flux tube, requiring upward curvature of the flux tube path along these sections and sometimes leading to unusual equilibrium paths of periodic, sinusoidal form.

  4. Siphon flows in isolated magnetic flux tubes. 3: The equilibrium path of the flux tube arch

    NASA Astrophysics Data System (ADS)

    Thomas, John H.; Montesinis, Benjamin

    1989-09-01

    The arched equilibrium path of a thin magnetic flux tube in a plane-stratified, nonmagnetic atmosphere is calculated for cases in which the flux tube contains a steady siphon flow. The large scale mechanical equilibrium of the flux tube involves a balance among the magnetic buoyancy force, the net magnetic tension force due to the curvature of the flux tube axis, and the inertial (centrifugal) force due to the siphon flow along curved streamlines. The ends of the flux tube are assumed to be pinned down by some other external force. Both isothermal and adiabatic siphon flows are considered for flux tubes in an isothermal external atmosphere. For the isothermal case, in the absence of a siphon flow the equilibrium path reduces to the static arch calculated by Parker (1975, 1979). The presence of a siphon flow causes the flux tube arch to bend more sharply, so that magnetic tension can overcome the additional straightening effect of the inertial force, and reduces the maximum width of the arch. The curvature of the arch increases as the siphon flow speed increases. For a critical siphon flow, with supercritical flow in the downstream leg, the arch is asymmetric, with greater curvature in the downstream leg of the arch. Adiabatic flow have qualitatively similar effects, except that adiabatic cooling reduces the buoyancy of the flux tube and thus leads to significantly wider arches. In some cases the cooling is strong enough to create negative buoyancy along sections of the flux tube, requiring upward curvature of the flux tube path along these sections and sometimes leading to unusual equilibrium paths of periodic, sinusoidal form.

  5. Siphon flows in isolated magnetic flux tubes. II - Adiabatic flows

    NASA Technical Reports Server (NTRS)

    Montesinos, Benjamin; Thomas, John H.

    1989-01-01

    This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point.

  6. Structure of sunspot penumbrae - Fallen magnetic flux tubes

    NASA Technical Reports Server (NTRS)

    Wentzel, Donat G.

    1992-01-01

    A model is presented of a sunspot penumbra involving magnetic flux tubes that have fallen into the photosphere and float there. An upwelling at the inner end of a fallen tube continuously provides additional gas. This gas flows along and lengthens the tube and is observable as the Evershed flow. Fallen flux tubes may appear as bright streaks near the upwelling, but they become dark filaments further out. The model is corroborated by recent optical high-resolution magnetic data regarding the penumbral filaments, by the 12-micron magnetic measurements relevant to the height of the temperature minimum, and by photographs of the umbra/penumbra boundary.

  7. TWISTED MAGNETIC FLUX TUBES IN THE SOLAR WIND

    SciTech Connect

    Zaqarashvili, Teimuraz V.; Vörös, Zoltán; Narita, Yasuhito; Bruno, Roberto

    2014-03-01

    Magnetic flux tubes in the solar wind can be twisted as they are transported from the solar surface, where the tubes are twisted due to photospheric motions. It is suggested that the twisted magnetic tubes can be detected as the variation of total (thermal+magnetic) pressure during their passage through the observing satellite. We show that the total pressure of several observed twisted tubes resembles the theoretically expected profile. The twist of the isolated magnetic tube may explain the observed abrupt changes of magnetic field direction at tube walls. We have also found some evidence that the flux tube walls can be associated with local heating of the plasma and elevated proton and electron temperatures. For the tubes aligned with the Parker spiral, the twist angle can be estimated from the change of magnetic field direction. Stability analysis of twisted tubes shows that the critical twist angle of the tube with a homogeneous twist is 70°, but the angle can further decrease due to the motion of the tube with respect to the solar wind stream. The tubes with a stronger twist are unstable to the kink instability, therefore they probably cannot reach 1 AU.

  8. Equilibrium model of thin magnetic flux tubes. [solar atmosphere

    NASA Technical Reports Server (NTRS)

    Bodo, G.; Ferrari, A.; Massaglia, S.; Kalkofen, W.; Rosner, R.

    1984-01-01

    The existence of a physically realizable domain in which approximations that lead to a self consistent solution for flux tube stratification in the solar atmosphere, without ad hoc hypotheses, is proved. The transfer equation is solved assuming that no energy transport other than radiative is present. Convective motions inside the tube are assumed to be suppressed by magnetic forces. Only one parameter, the plasma beta at tau = 0, must be specified, and this can be estimated from observations of spatially resolved flux tubes.

  9. Explosive instability and erupting flux tubes in a magnetized plasma

    PubMed Central

    Cowley, S. C.; Cowley, B.; Henneberg, S. A.; Wilson, H. R.

    2015-01-01

    The eruption of multiple flux tubes in a magnetized plasma is proposed as a mechanism for explosive release of energy in plasmas. A significant fraction of the linearly stable isolated flux tubes are shown to be metastable in a box model magnetized atmosphere in which ends of the field lines are embedded in conducting walls. The energy released by destabilizing such field lines can be a large proportion of the gravitational energy stored in the system. This energy can be released in a fast dynamical time. PMID:26339193

  10. Magnetic field characters of returning flux tubes in Saturn's magnetosphere

    NASA Astrophysics Data System (ADS)

    Lai, Hairong; Russell, Christopher; Jia, Yingdong; Wei, Hanying

    2016-04-01

    Deep in the Saturnian magnetosphere, water-group neutrals are ionized after being released from the plume of Enceladus at 4 RS. This forms a plasma disk from 2.5 to 8 RS around Saturn and the typical source rate is 12~250 kg/s. Such plasma addition must be shed to the solar wind ultimately to maintain the plasma density in the magnetosphere in long term average. In this plasma transfer process, the magnetic flux also convects outward. To conserve the total magnetic flux imposed on the magnetosphere by the planet's internal dynamo, the magnetic flux has to return to the inner magnetosphere. Flux tubes are found to be the major form of such return. Determining such flux tubes is essential in understanding the breathing of Saturn magnetosphere. We investigated 10 years of Cassini magnetometer data to identify over six hundred flux-returning events between 4 and 18 in L. Statistical properties are presented, to constrain the origin, transport and evolution of these flux tubes.

  11. MHD waves on solar magnetic flux tubes - Tutorial review

    NASA Technical Reports Server (NTRS)

    Hollweg, Joseph V.

    1990-01-01

    Some of the highly simplified models that have been developed for solar magnetic flux tubes, which are intense photospheric-level fields confined by external gas pressure but able to vary rapidly with height, are presently discussed with emphasis on the torsional Alfven mode's propagation, reflection, and non-WKB properties. The 'sausage' and 'kink' modes described by the thin flux-tube approximation are noted. Attention is also given to the surface waves and resonance absorption of X-ray-emitting loops, as well as to the results of recent work on the resonant instabilities that occur in the presence of bulk flows.

  12. MHD waves on solar magnetic flux tubes - Tutorial review

    NASA Astrophysics Data System (ADS)

    Hollweg, Joseph V.

    Some of the highly simplified models that have been developed for solar magnetic flux tubes, which are intense photospheric-level fields confined by external gas pressure but able to vary rapidly with height, are presently discussed with emphasis on the torsional Alfven mode's propagation, reflection, and non-WKB properties. The 'sausage' and 'kink' modes described by the thin flux-tube approximation are noted. Attention is also given to the surface waves and resonance absorption of X-ray-emitting loops, as well as to the results of recent work on the resonant instabilities that occur in the presence of bulk flows.

  13. Incompressible magnetohydrodynamic modes in the thin magnetically twisted flux tube

    NASA Astrophysics Data System (ADS)

    Cheremnykh, O. K.; Fedun, V.; Kryshtal, A. N.; Verth, G.

    2017-08-01

    Context. Observations have shown that twisted magnetic fields naturally occur, and indeed are omnipresent in the Sun's atmosphere. It is therefore of great theoretical interest in solar atmospheric waves research to investigate the types of magnetohydrodynamic (MHD) wave modes that can propagate along twisted magnetic flux tubes. Aims: Within the framework of ideal MHD, the main aim of this work is to investigate small amplitude incompressible wave modes of twisted magnetic flux tubes with m ≥ 1. The axial magnetic field strength inside and outside the tube will be allowed to vary, to ensure the results will not be restricted to only cold plasma equilibria conditions. Methods: The dispersion equation for these incompressible linear MHD wave modes was derived analytically by implementing the long wavelength approximation. Results: It is shown, in the long wavelength limit, that both the frequency and radial velocity profile of the m = 1 kink mode are completely unaffected by the choice of internal background magnetic twist. However, fluting modes with m ≥ 2 are sensitive to the particular radial profile of magnetic twist chosen. Furthermore, due to background twist, a low frequency cut-off is introduced for fluting modes that is not present for kink modes. From an observational point of view, although magnetic twist does not affect the propagation of long wavelength kink modes, for fluting modes it will either work for or against the propagation, depending on the direction of wave travel relative to the sign of the background twist.

  14. Statistical Flux Tube Properties of 3D Magnetic Carpet Fields

    NASA Astrophysics Data System (ADS)

    Close, R. M.; Parnell, C. E.; Mackay, D. H.; Priest, E. R.

    2003-02-01

    The quiet-Sun photosphere consists of numerous magnetic flux fragments of both polarities that evolve with granular and supergranular flow fields. These concentrations give rise to a web of intermingled magnetic flux tubes which characterise the coronal magnetic field. Here, the nature of these flux tubes is studied. The photosphere is taken to be the source plane and each photospheric fragment is represented by a series of point sources. By analysing the potential field produced by these sources, it is found that the distribution of flux tube lengths obtained by (i) integrating forward from positive sources and (ii) tracing back from negative sources is highly dependent on the total flux imbalance within the region of interest. It is established that the relation between the footpoint separation of a flux tube and its height cannot be assumed to be linear. Where there is a significant imbalance of flux within a region, it is found that fragments of the dominant polarity will have noticeably more connections, on average, than the minority polarity fragments. Despite this difference, the flux from a single fragment of either polarity is typically divided such that (i) 60-70% connects to one opposite-polarity fragment, (ii) 25-30% goes to a further 1 to 2 opposite-polarity fragments, and (iii) any remaining flux may connect to as many as another 50 or more other opposite-polarity fragments. This is true regardless of any flux imbalance within the region. It is found that fragments connect preferentially to their nearest neighbours, with, on average, around 60-70% of flux closing down within 10 Mm of a typical fragment. Only 50% of the flux in a quiet region extends higher than 2.5 Mm above the solar surface and 5-10% extends higher than 25 Mm. The fragments that contribute to the field above this height cover a range of sizes, with even the smallest of fragments contributing to the field at heights of over 50 Mm.

  15. Wave function properties of a single and a system of magnetic flux tube(s) oscillations

    NASA Astrophysics Data System (ADS)

    Esmaeili, Shahriar; Nasiri, Mojtaba; Dadashi, Neda; Safari, Hossein

    2016-10-01

    In this study, the properties of wave functions of the MHD oscillations for a single and a system of straight flux tubes are investigated. Magnetic flux tubes with a straight magnetic field and longitudinal density stratification were considered in zero-β approximation. A single three-dimensional wave equation (eigenvalue problem) is solved for longitudinal component of the perturbed magnetic field using the finite element method. Wave functions (eigenfunction of wave equation) of the MHD oscillations are categorized into sausage, kink, helical kink, and fluting modes. Exact recognition of the wave functions and the frequencies of oscillations can be used in coronal seismology and also helps to the future high-resolution instruments that would be designed for studying the properties of the solar loop oscillations in details. The properties of collective oscillations of nonidentical and identical system of flux tubes and their interactions are studied. The ratios of frequencies, the oscillation frequencies of a system of flux tubes to their equivalent monolithic tube (ω sys/ω mono), are obtained between 0.748 and 0.841 for a system of nonidentical tubes, whereas the related ratios of frequencies for a system of identical flux tubes are fluctuated around 0.761.

  16. A magnetohydrodynamic simulation of the formation of magnetic flux tubes at the earth's dayside magnetopause

    NASA Technical Reports Server (NTRS)

    Ogino, Tatsuki; Walker, Raymond J.; Ashour-Abdalla, Maha

    1989-01-01

    Dayside magnetic reconnection was studied by using a three-dimensional global magnetohydrodynamic simulation of the interaction between the solar wind and the magnetosphere. Two different mechanisms were found for the formation of magnetic flux tubes at the dayside magnetopause, which depend on the orientation of the interplanetary magnetic field (IMF). The dayside magnetic flux tubes occur only when the IMF has a southward component. A strongly twisted and localized magnetic flux tube similar to magnetic flux ropes appears at the subsolar magnetopause when the IMF has a large B(y) component. When the B(y) component is small, twin flux tubes appear at the dayside magnetopause. Both types of magnetic flux tube are consistent with several observational features of flux transfer events and are generated by antiparallel magnetic reconnection.

  17. A magnetohydrodynamic simulation of the formation of magnetic flux tubes at the Earth's dayside magnetopause

    SciTech Connect

    Ogino, Tatsuki ); Walker, R.J.; Ashour-Abdalla, Maha )

    1989-02-01

    The authors have studied dayside magnetic reconnection by using a three-dimensional global magnetohydrodynamic simulation of the interaction between the solar wind and the magnetosphere. They found two different mechanisms for the formation of magnetic flux tubes at the dayside magnetopause which depend on the orientation of the interplanetary magnetic field (IMF). The dayside magnetic flux tubes occur only when the IMF has a southward component. A strongly twisted and localized magnetic flux tube similar to magnetic flux ropes appears at the subsolar magnetopause when the IMF has a large B{sub y} component. When the B{sub y} component is small, twin flux tubes appear at the dayside magnetopause. Both types of magnetic flux tube are consistent with several observational features of flux transfer events and are generated by antiparallel magnetic reconnection.

  18. Plasma dynamics on current-carrying magnetic flux tubes

    NASA Technical Reports Server (NTRS)

    Swift, Daniel W.

    1992-01-01

    A 1D numerical simulation is used to investigate the evolution of a plasma in a current-carrying magnetic flux tube of variable cross section. A large potential difference, parallel to the magnetic field, is applied across the domain. The result is that density minimum tends to deepen, primarily in the cathode end, and the entire potential drop becomes concentrated across the region of density minimum. The evolution of the simulation shows some sensitivity to particle boundary conditions, but the simulations inevitably evolve into a final state with a nearly stationary double layer near the cathode end. The simulation results are at sufficient variance with observations that it appears unlikely that auroral electrons can be explained by a simple process of acceleration through a field-aligned potential drop.

  19. Riemannian geometry of twisted magnetic flux tubes in almost helical plasma flows

    SciTech Connect

    Garcia de Andrade, L.C.

    2006-02-15

    Riemannian geometry of curves applied recently by Ricca [Fluid Dyn. Res 36, 319 (2005)] in the case of inflectional disequilibrium of twisted magnetic flux tubes is used here to compute the magnetic helicity force-free field case. Here the application of Lorentz force-free to the magnetic flux tube in tokamaks allows one to obtain an equation that generalizes the cylindrical tokamak equation by a term that contains the curvature of the magnetic flux tube. Another example of the use of the magnetic flux tube is done by taking the electron magnetohydrodynamics (MHD) fluid model (EMHD) of plasma physics that allows one to compute the velocity of the fluid in helical and almost helical flows in terms of the Frenet torsion of thin magnetic flux tubes. The cases of straight and curved twisted tubes are examined. Second-order effects on the Frenet torsion arise on the poloidal component of the magnetic field, while curvature effects appear in the toroidal component. The magnetic fields are computed in terms of the penetration depth used in superconductors. The ratio between poloidal and toroidal components of the magnetic field depends on the torsion and curvature of the magnetic flux tube. It is shown that the rotation of the almost helical plasma flow contributes to the twist of the magnetic flux tube through the total Frenet torsion along the tube.

  20. Magnetohydrostatic Equilibrium. II. Three-dimensional Multiple Open Magnetic Flux Tubes in the Stratified Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Gent, F. A.; Fedun, V.; Erdélyi, R.

    2014-07-01

    A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modeled analytically, within a realistic stratified atmosphere subject to solar gravity. This extends results for a single magnetic flux tube in magnetohydrostatic equilibrium, described in Gent et al. Self-similar magnetic flux tubes are combined to form magnetic structures, which are consistent with high-resolution observations. The observational evidence supports the existence of strands of open flux tubes and loops persisting in a relatively steady state. Self-similar magnetic flux tubes, for which an analytic solution to the plasma density and pressure distribution is possible, are combined. We calculate the appropriate balancing forces, applying to the equations of momentum and energy conservation to preserve equilibrium. Multiplex flux tube configurations are observed to remain relatively stable for up to a day or more, and it is our aim to apply our model as the background condition for numerical studies of energy transport mechanisms from the solar surface to the corona. We apply magnetic field strength, plasma density, pressure, and temperature distributions consistent with observational and theoretical estimates for the lower solar atmosphere. Although each flux tube is identical in construction apart from the location of the radial axis, combinations can be applied to generate a non-axisymmetric magnetic field with multiple non-uniform flux tubes. This is a considerable step forward in modeling the realistic magnetized three-dimensional equilibria of the solar atmosphere.

  1. Magnetohydrostatic equilibrium. II. Three-dimensional multiple open magnetic flux tubes in the stratified solar atmosphere

    SciTech Connect

    Gent, F. A.; Erdélyi, R.; Fedun, V.

    2014-07-01

    A system of multiple open magnetic flux tubes spanning the solar photosphere and lower corona is modeled analytically, within a realistic stratified atmosphere subject to solar gravity. This extends results for a single magnetic flux tube in magnetohydrostatic equilibrium, described in Gent et al. Self-similar magnetic flux tubes are combined to form magnetic structures, which are consistent with high-resolution observations. The observational evidence supports the existence of strands of open flux tubes and loops persisting in a relatively steady state. Self-similar magnetic flux tubes, for which an analytic solution to the plasma density and pressure distribution is possible, are combined. We calculate the appropriate balancing forces, applying to the equations of momentum and energy conservation to preserve equilibrium. Multiplex flux tube configurations are observed to remain relatively stable for up to a day or more, and it is our aim to apply our model as the background condition for numerical studies of energy transport mechanisms from the solar surface to the corona. We apply magnetic field strength, plasma density, pressure, and temperature distributions consistent with observational and theoretical estimates for the lower solar atmosphere. Although each flux tube is identical in construction apart from the location of the radial axis, combinations can be applied to generate a non-axisymmetric magnetic field with multiple non-uniform flux tubes. This is a considerable step forward in modeling the realistic magnetized three-dimensional equilibria of the solar atmosphere.

  2. The equilibrium structure of thin magnetic flux tubes. II. [in sun and late stars

    NASA Technical Reports Server (NTRS)

    Kalkofen, W.; Rosner, R.; Ferrari, A.; Massaglia, S.

    1986-01-01

    The thermal structure of the medium inside thin, vertical magnetic flux tubes embedded in a given external atmosphere is investigated, assuming cylindrical symmetry and a depth-independent plasma beta. The variation with tube radius of the temperature on the tube axis is computed and the temperature on the tube wall is estimated. The temperature variation across the flux tube is found to be due to the depth variation of the intensity and to the density stratification of the atmosphere. Since the temperature difference between the axis and the wall is small in thin flux tubes (of the order of 10 percent), the horizontal temperature gradient may often be neglected and the temperature in a tube of given radius may be described by a single function of depth. Thus, a more detailed numerical treatment of the radiative transfer within thin flux tubes can be substantially simplified by neglecting horizontal temperature differences within the flux tube proper.

  3. Propagation of nonlinear, radiatively damped longitudinal waves along magnetic flux tubes in the solar atmosphere

    NASA Technical Reports Server (NTRS)

    Herbold, G.; Ulmschneider, P.; Spruit, H. C.; Rosner, R.

    1985-01-01

    For solar magnetic flux tubes three types of waves are compared: longitudinal MHD tube waves, acoustic tube waves propagating in the same tube geometry but with rigid walls and ordinary acoustic waves in plane geometry. It is found that the effect of the distensibility of the tube is small and that longitudinal waves are essentially acoustic tube waves. Due to the tube geometry there is considerable difference between longitudinal waves or acoustic tube waves and ordinary acoustic waves. Longitudinal waves as well as acoustic tube waves show a smaller amplitude growth, larger shock formation heights, smaller mean chromospheric temperature but a steeper dependence of the temperature gradient on wave period.

  4. Dilation of force-free magnetic flux tubes. [solar magnetic field profiles

    NASA Technical Reports Server (NTRS)

    Frankenthal, S.

    1977-01-01

    A general study is presented of the mapping functions which relate the magnetic-field profiles across a force-free rope in segments subjected to various external pressures. The results reveal that if the external pressure falls below a certain critical level (dependent on the flux-current relation which defines the tube), the magnetic profile consists of an invariant core sheathed in a layer permeated by an azimuthal magnetic field.

  5. HOW MUCH DOES A MAGNETIC FLUX TUBE EMERGE INTO THE SOLAR ATMOSPHERE?

    SciTech Connect

    Magara, T.

    2012-03-20

    The emergence process of the magnetic field into the solar atmosphere plays an essential role in determining the configuration of the magnetic field and its activity on the Sun. This paper focuses on how much the magnetic flux contained by a flux tube emerges into the solar atmosphere, which is the key to understanding the physical mechanism of solar eruptions. By comparing a kinematic model of an emerging flux tube to a series of magnetohydrodynamic simulations, we derive the characteristics of the emergence process, showing how the process depends on the pre-emerged state of the magnetic field such as the radius of a flux tube, field strength, field-line twist, and wavelength of undulation assumed by the flux tube. We also discuss the relationship between magnetic configurations and their stability on the Sun.

  6. Radiative Heating and the Buoyant Rise of Magnetic Flux Tubes in the Solar interior

    NASA Astrophysics Data System (ADS)

    Fan, Y.; Fisher, G. H.

    1996-06-01

    We study the effect of radiative heating on the evolution of thin magnetic flux tubes in the solar interior and on the eruption of magnetic flux loops to the surface. Magnetic flux tubes experience radiative heating because (1) the mean temperature gradient in the lower convection zone and the overshoot region deviates substantially from that of radiative equilibrium, and hence there is a non-zero divergence of radiative heat flux; and (2) the magnetic pressure of the flux tube causes a small change of the thermodynamic properties within the tube relative to the surrounding field-free fluid, resulting in an additional divergence of radiative heat flux. Our calculations show that the former constitutes the dominant source of radiative heating experienced by the flux tube. In the overshoot region, the radiative heating is found to cause a quasi-static rising of the toroidal flux tubes with an upward drift velocity ˜ 10-3|δ| cm s-1, where δ ≡ ∇e - ∇ad < 0 describes the subadiabaticity in the overshoot layer. The upward drift velocity does not depend sensitively on the field strength of the flux tubes. Thus in order to store toroidal flux tubes in the overshoot region for a period comparable to the length of the solar cycle, the magnitude of the subadiabaticity δ(< 0) in the overshoot region must be as large as ˜ 3 × 10-4. We discuss the possibilities for increasing the magnitude of δ and for reducing the rate of radiative heating of the flux tubes in the overshoot region. Using numerical simulations we study the formation of ‘Ω’-shaped emerging loops from toroidal flux tubes in the overshoot region as a result of radiative heating. The initial toroidal tube is assumed to be non-uniform in its thermodynamic properties along the tube and lies at varying depths beneath the base of the convection zone. The tube is initially in a state of neutral buoyancy with the internal density of the tube plasma equal to the local external density. We find from our

  7. CONDITIONS FOR TRANSVERSE WAVES PROPAGATION ALONG THIN MAGNETIC FLUX TUBES ON THE SUN

    SciTech Connect

    Lopin, Igor; Nagorny, Ivan

    2013-09-10

    The propagation of kink waves in the thin gravity stratified flux tubes with a generalized magnetic field distribution model is considered in cylindrical geometry. The new kink wave equations for both wave variables are obtained. It is shown that the inclusion of the radial component of an unperturbed tube magnetic field sufficiently transforms the conditions for the propagation of transverse waves. It is demonstrated that, for the models of isothermal and polytropic atmosphere in the tube and its environment, the propagation of kink waves along thin magnetic flux tubes is cutoff-free.

  8. Sausage Instabilities on top of Kinking Lengthening Current-Carrying Magnetic Flux Tubes

    NASA Astrophysics Data System (ADS)

    von der Linden, Jens; You, Setthivoine

    2015-11-01

    Observations indicate that the dynamics of magnetic flux tubes in our cosmos and terrestrial experiments involve fast topological change beyond MHD reconnection. Recent experiments suggest that hierarchies of instabilities coupling disparate plasma scales could be responsible for this fast topological change by accessing two-fluid and kinetic scales. This study will explore the possibility of sausage instabilities developing on top of a kink instability in lengthening current-carrying magnetic flux tubes. Current driven flux tubes evolve over a wide range of aspect ratios k and current to magnetic flux ratios λ . An analytical stability criterion and numerical investigations, based on applying Newcomb's variational approach to idealized magnetic flux tubes with core and skin currents, indicate a dependence of the stability boundaries on current profiles and overlapping kink and sausage unstable regions in the k - λ trajectory of the flux tubes. A triple electrode planar plasma gun (Mochi.LabJet) is designed to generate flux tubes with discrete core and skin currents. Measurements from a fast-framing camera and a high resolution magnetic probe are being assembled into stability maps of the k - λ space of flux tubes. This work was sponsored in part by the US DOE Grant DE-SC0010340.

  9. Dynamics of Magnetic Flux Tubes in an Advective Flow around a Black Hole

    NASA Astrophysics Data System (ADS)

    Deb, Arnab; Chakrabarti, Sandip Kumar; Giri, Kinsuk

    2016-07-01

    Magnetic fields cannibalized by an accretion flow would very soon have a dominant toroidal component. Without changing the topology, we study the movements of these flux tubes inside a geometrically thick advective disk which undergo centrifugal pressure supported shocks. We also consider the effects of the flux tubes on the flow. We use a finite element method (Total Variation Diminishing) for this purpose and specifically focussed whether the flux tubes contribute to changes in outflow properties in terms of its collimation and outflow rates. It is seen that depending upon the cross sectional radius of the flux tubes (which control the drag force), these field lines may move towards the central object or oscillate vertically before eventually escaping out of the funnel wall (pressure zero surface). These interesting results obtained with and without flux tubes point to the role the flux tubes play in collimation of jets and outflows.

  10. Dynamic and Stagnating Plasma Flow Leading to Magnetic-Flux-Tube Collimation

    NASA Astrophysics Data System (ADS)

    You, Setthivoine

    2006-10-01

    This talk presents experimental observations, first reported by You, Yun, Bellan in PRL (art. 045002, 2005), strongly supporting the ``MHD pump-collimation'' model proposed by Bellan in Phys. Plasmas (vol. 10, p.1999, 2003). Collimated, plasma-filled, magnetic flux tubes are observed over a tremendous range of scales. In laboratory plasmas, on the surface of the Sun, or jetting out of galactic cores, these flux tubes are extremely collimated, with cross-sections that do not vary much along the length of the tube even in the absence of external magnetic fields or any significant ambient medium pressure. Furthermore, these flux tubes are not in static equilibrium but exhibit strong plasma flows on a rapid time-scale compared to their overall motion within their surroundings. The Caltech experiment simulates magnetically-driven astrophysical jets at the laboratory scale by imposing boundary conditions analogous to astrophysical jet boundary conditions and with plasma dimensionless numbers comparable to numerical MHD simulations. Observations show a distinct sequence of events. The initial flux tubes flare out into the large vacuum, because the magnetic field weakens away from the source. As electrical current flows, the flux tubes become denser and more collimated while sucking plasma from gas sources at the system boundary, effectively acting like a magnetohydrodynamic pump. These flux tubes then merge together into a single column which jets out into the vacuum. The jet continues the same pumping process, to become even denser and more collimated, until either the electrical current or the supply of particles stop. The strong plasma flow convects frozen-in magnetic flux to regions of weaker magnetic field at the end of the tube, and as the flow stagnates there, magnetic flux piles up, pinching the tube into a collimated filament.

  11. Sunspots and the physics of magnetic flux tubes. V - Mutual hydrodynamic forces between neighboring tubes

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1979-01-01

    The mutual hydrodynamic forces between parallel cylinders in a moving fluid are illustrated through several formal examples. Parallel tubes in a uniform flow are attracted or repelled depending on whether they are side by side or one ahead of the other, respectively. A pulsating or undulating tube attracts all other neighboring tubes toward itself. These hydrodynamic effects suggest that the separate flux tubes beneath the sunspots exert significant attractive forces on each other.

  12. Equilibrium structure of solar magnetic flux tubes: Energy transport with multistream radiative transfer

    NASA Technical Reports Server (NTRS)

    Hasan, S. S.; Kalkofen, W.

    1994-01-01

    We examine the equilibrium structure of vertical intense magnetic flux tubes on the Sun. Assuming cylindrical geometry, we solve the magnetohydrostatic equations in the thin flux-tube approximation, allowing for energy transport by radiation and convection. The radiative transfer equation is solved in the six-stream approximation, assuming gray opacity and local thermodynamic equilibrium. This constitutes a significant improvement over a previous study, in which the transfer was solved using the multidimensional generalization of the Eddington approximation. Convection in the flux tube is treated using mixing-length theory, with an additional parameter alpha, characterizing the suppression of convective energy transport in the tube by the strong magnetic field. The equations are solved using the method of partial linearization. We present results for tubes with different values of the magnetic field strength and radius at a fixed depth in the atmosphere. In general, we find that, at equal geometric heights, the temperature on the tube axis, compared to the ambient medium, is higher in the photosphere and lower in the convection zone, with the difference becoming larger for thicker tubes. At equal optical depths the tubes are generally hotter than their surroundings. The results are comparatively insensitive to alpha but depend upon whether radiative and convective energy transport operate simultaneously or in separate layers. A comparison of our results with semiempirical models shows that the temperature and intensity contrast are in broad agreement. However, the field strengths of the flux-tube models are somewhat lower than the values inferred from observations.

  13. Equilibrium structure of solar magnetic flux tubes: Energy transport with multistream radiative transfer

    NASA Technical Reports Server (NTRS)

    Hasan, S. S.; Kalkofen, W.

    1994-01-01

    We examine the equilibrium structure of vertical intense magnetic flux tubes on the Sun. Assuming cylindrical geometry, we solve the magnetohydrostatic equations in the thin flux-tube approximation, allowing for energy transport by radiation and convection. The radiative transfer equation is solved in the six-stream approximation, assuming gray opacity and local thermodynamic equilibrium. This constitutes a significant improvement over a previous study, in which the transfer was solved using the multidimensional generalization of the Eddington approximation. Convection in the flux tube is treated using mixing-length theory, with an additional parameter alpha, characterizing the suppression of convective energy transport in the tube by the strong magnetic field. The equations are solved using the method of partial linearization. We present results for tubes with different values of the magnetic field strength and radius at a fixed depth in the atmosphere. In general, we find that, at equal geometric heights, the temperature on the tube axis, compared to the ambient medium, is higher in the photosphere and lower in the convection zone, with the difference becoming larger for thicker tubes. At equal optical depths the tubes are generally hotter than their surroundings. The results are comparatively insensitive to alpha but depend upon whether radiative and convective energy transport operate simultaneously or in separate layers. A comparison of our results with semiempirical models shows that the temperature and intensity contrast are in broad agreement. However, the field strengths of the flux-tube models are somewhat lower than the values inferred from observations.

  14. Nonlinear fast sausage waves in homogeneous magnetic flux tubes

    NASA Astrophysics Data System (ADS)

    Mikhalyaev, Badma B.; Ruderman, Michael S.

    2015-12-01

    > We consider fast sausage waves in straight homogeneous magnetic tubes. The plasma motion is described by the ideal magnetohydrodynamic equations in the cold plasma approximation. We derive the nonlinear Schrödinger equation describing the nonlinear evolution of an envelope of a carrier wave. The coefficients of this equation are expressed in terms Bessel and modified Bessel functions. They are calculated numerically for various values of parameters. In particular, we show that the criterion for the onset of the modulational or Benjamin-Fair instability is satisfied. The implication of the obtained results for solar physics is discussed.

  15. Sausage instabilities on top of kinking lengthening current-carrying magnetic flux tubes

    NASA Astrophysics Data System (ADS)

    von der Linden, Jens; You, Setthivoine

    2017-05-01

    We theoretically explore the possibility of sausage instabilities developing on top of a kink instability in lengthening current-carrying magnetic flux tubes. Observations indicate that the dynamics of magnetic flux tubes in our cosmos and terrestrial experiments can involve topological changes faster than time scales predicted by resistive magnetohydrodynamics. Recent laboratory experiments suggest that hierarchies of instabilities, such as kink and Rayleigh-Taylor, could be responsible for initiating fast topological changes by locally accessing two-fluid and kinetic regimes. Sausage instabilities can also provide this coupling mechanism between disparate scales. Flux tube experiments can be classified by the flux tube's evolution in a configuration space described by a normalized inverse aspect-ratio k ¯ and current-to-magnetic flux ratio λ ¯ . A lengthening current-carrying magnetic flux tube traverses this k ¯ - λ ¯ space and crosses stability boundaries. We derive a single general criterion for the onset of the sausage and kink instabilities in idealized magnetic flux tubes with core and skin currents. The criterion indicates a dependence of the stability boundaries on current profiles and shows overlapping kink and sausage unstable regions in the k ¯ - λ ¯ space with two free parameters. Numerical investigation of the stability criterion reduces the number of free parameters to a single one that describes the current profile and confirms the overlapping sausage and kink unstable regions in k ¯ - λ ¯ space. A lengthening, ideal current-carrying magnetic flux tube can therefore become sausage unstable after it becomes kink unstable.

  16. Dynamics of local isolated magnetic flux tubes in a fast-rotating stellar atmosphere

    SciTech Connect

    Chou, W.; Tajima, C.T.; Matsumoto, R. |; Shibata, K.

    1998-01-01

    Dynamics of magnetic flux tubes in the fast rotating stellar atmosphere is studied. We focus on the effects and signatures of the instability of the flux tube emergence influenced by the Coriolis force. We present the result from a linear stability analysis and discuss its possible signatures in the course of the evolution of G-type and M-type stars. We present a three dimensional magnetohydrodynamical simulation of local isolated magnetic flux tubes under a magnetic buoyancy instability in co-rotating Cartesian coordinates. We find that the combination of the buoyancy instability and the Coriolis effect gives rise to a mechanism, to twist the emerging magnetic flux tube into a helical structure. The tilt angle, east-west asymmetry and magnetic helicity of the Twisted flux tubes in the simulations are studied in detail. The linear and nonlinear analyses provide hints as to what kind of pattern of large spots in young M-type main-sequence stars might be observed. We find that young and old G-type stars may have different distributions of spots while M-type stars may always have low latitudes spots. The size of stellar spots may decrease when a star becomes older, due to the decreasing of magnetic field. A qualitative comparison with solar observations is also presented.

  17. Simulation of magnetic flux leakage: Application to tube inspection

    NASA Astrophysics Data System (ADS)

    Prémel, Denis; Fnaeich, E. A.; Djafa, S.; Pichon, L.; Trillon, A.; Bisiaux, B.

    2012-05-01

    The detection of flaws in steel pipes using Magnetic Flux Leakage (MFL) consists in detecting magnetic flux leaks outside the pipe, either with a magnetic sensor or with an induction coil, while the pipe is rotating. In the Vallourec group, many NDT units use MFL for testing ferromagnetic pipes. In order to improve the performances of flaw detection, CEA LIST and the Vallourec Research Aulnoye (VRA) group are collaborating on MFL modelling. The aim is to be able to perform parametric studies thanks to a fast 3D numerical model dedicated to MFL systems. A simplified 2D geometry has already been derived for the development of first simulation tools. When considering the B-H curve of ferromagnetic materials, the non-linear magnetostatic problem can be solved with the generalized boundary element method (BEMG), which comes to the evaluation of two equivalent scalar potentials: the surface charge density and the volume charge density. When applying the Galerkin method for the discretization of integral equations, the particularity of this numerical model lies in the implementation of high order basis functions for the interpolation of the scalar unknowns. This paper presents some first numerical results for the numerical validation of the semi-analytical model.

  18. NUMERICAL EXPERIMENTS ON THE TWO-STEP EMERGENCE OF TWISTED MAGNETIC FLUX TUBES IN THE SUN

    SciTech Connect

    Toriumi, S.; Yokoyama, T.

    2011-07-10

    We present the new results of the two-dimensional numerical experiments on the cross-sectional evolution of a twisted magnetic flux tube rising from the deeper solar convection zone (-20,000 km) to the corona through the surface. The initial depth is 10 times deeper than most of the previous calculations focusing on the flux emergence from the uppermost convection zone. We find that the evolution is illustrated by the following two-step process. The initial tube rises due to its buoyancy, subject to aerodynamic drag due to the external flow. Because of the azimuthal component of the magnetic field, the tube maintains its coherency and does not deform to become a vortex roll pair. When the flux tube approaches the photosphere and expands sufficiently, the plasma on the rising tube accumulates to suppress the tube's emergence. Therefore, the flux decelerates and extends horizontally beneath the surface. This new finding owes to our large-scale simulation, which simultaneously calculates the dynamics within the interior as well as above the surface. As the magnetic pressure gradient increases around the surface, magnetic buoyancy instability is triggered locally and, as a result, the flux rises further into the solar corona. We also find that the deceleration occurs at a higher altitude than assumed in our previous experiment using magnetic flux sheets. By conducting parametric studies, we investigate the conditions for the two-step emergence of the rising flux tube: field strength {approx}> 1.5 x 10{sup 4} G and the twist {approx}> 5.0 x 10{sup -4} km{sup -1} at -20,000 km depth.

  19. Numerical simulations of magnetic Kelvin-Helmholtz instability at a twisted solar flux tube

    NASA Astrophysics Data System (ADS)

    Murawski, K.; Chmielewski, P.; Zaqarashvili, T. V.; Khomenko, E.

    2016-07-01

    The paper aims to study the response of a solar small-scale and weak magnetic flux tube to photospheric twisting motions. We numerically solve three-dimensional ideal magnetohydrodynamic equations to describe the evolution of the perturbation within the initially static flux tube, excited by twists in the azimuthal component of the velocity. These twists produce rotation of the magnetic field lines. Perturbation of magnetic field lines propagates upwardly, driving vertical and azimuthal flow as well as plasma compressions and rarefactions in the form of eddies. We conclude that these eddies result from the sheared azimuthal flow which seeds Kelvin-Helmholtz instability (KHI) between the flux tube and the ambient medium. Numerically obtained properties of the KHI confirm the analytical predictions for the occurrence of the instability.

  20. Axisymmetric and non-axisymmetric modulated MHD waves in magnetic flux tubes

    NASA Astrophysics Data System (ADS)

    Chargeishvili, B. B.; Japaridze, D. R.

    2016-02-01

    Nonlinear modulated both axisymmetric and non-axisymmetric MHD wave propagation in magnetic flux tubes is studied. In the cylindrical coordinates, ordinary differential equation with cubic nonlinearity is derived. In both cases of symmetry, the equation has solitary solutions. Modulation stability of the solutions is studied. The results of the study show that the propagation of axisymmetric soliton causes rising of plasma temperature in peripheral regions of a magnetic flux tube. In the non-axisymmetric case, it gives also temperature rising effect. Results of theoretical study are examined on idealized model of chromospheric spicule.

  1. Numerical simulations of three-dimensional magnetic swirls in a solar flux-tube

    NASA Astrophysics Data System (ADS)

    Chmielewski, Piotr; Murawski, Krzysztof; Solov'ev, Alexandr A.

    2014-07-01

    We aim to numerically study evolution of Alfvén waves that accompany short-lasting swirl events in a solar magnetic flux-tube that can be a simple model of a magnetic pore or a sunspot. With the use of the FLASH code we numerically solve three-dimensional ideal magnetohydrodynamic equations to simulate twists which are implemented at the top of the photosphere in magnetic field lines of the flux-tube. Our numerical results exhibit swirl events and Alfvén waves with associated clockwise and counterclockwise rotation of magnetic lines, with the largest values of vorticity at the bottom of the chromosphere, and a certain amount of energy flux.

  2. Spectropolarimetric Evidence for a Siphon Flow along an Emerging Magnetic Flux Tube

    NASA Astrophysics Data System (ADS)

    Requerey, Iker S.; Ruiz Cobo, B.; Del Toro Iniesta, J. C.; Orozco Suárez, D.; Blanco Rodríguez, J.; Solanki, S. K.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Riethmüller, T. L.; van Noort, M.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.

    2017-03-01

    We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board the sunrise balloon-borne solar observatory. We obtain the full vector magnetic field and the line of sight (LOS) velocity through inversions of the Fe i line at 525.02 nm with the SPINOR code. The derived vector magnetic field is used to trace magnetic field lines. Two magnetic flux concentrations with different polarities and LOS velocities are found to be connected by a group of arch-shaped magnetic field lines. The positive polarity footpoint is weaker (1100 G) and displays an upflow, while the negative polarity footpoint is stronger (2200 G) and shows a downflow. This configuration is naturally interpreted as a siphon flow along an arched magnetic flux tube.

  3. Numerical Simulations of Torsional Alfvén Waves in Axisymmetric Solar Magnetic Flux Tubes

    NASA Astrophysics Data System (ADS)

    Wójcik, D.; Murawski, K.; Musielak, Z. E.; Konkol, P.; Mignone, A.

    2017-02-01

    We numerically investigate Alfvén waves propagating along an axisymmetric and non-isothermal solar flux tube embedded in the solar atmosphere. The tube magnetic field is current-free and diverges with height, and the waves are excited by a periodic driver along the tube magnetic field lines. The main results are that the two wave variables, the velocity and magnetic field perturbations in the azimuthal direction, behave differently as a result of gradients of the physical parameters along the tube. To explain these differences in the wave behavior, the time evolution of the wave variables and the resulting cutoff period for each wave variable are calculated and used to determine regions in the solar chromosphere where strong wave reflection may occur.

  4. The Role of Twisted Magnetic Flux Tubes in Topological Space Weather Forecasting

    NASA Astrophysics Data System (ADS)

    Nightingale, R. W.

    2008-12-01

    More and more twisted magnetic flux tubes are being identified in the solar active regions of solar cycle 23 utilizing imagery from high resolution satellite instrumentation, such as TRACE, Hinode, and SOHO/MDI. The twisted flux tubes carry energy and helicity via the Poynting Flux from below the photosphere up into the corona, where much of it is stored in the non-potentiality of the fields, many times visible in the form of sigmoidal and anti-sigmoidal shapes, until dissipation occurs mostly following eruptive events. The twisted flux tubes are easily observed and measured in TRACE whitelight in cross section as sunspots at the photosphere, which rotate about their umbral centers. The first results presented at the 2007 Fall AGU from a statistical study on the number of rotating sunspots showed that almost all of the measurable sunspots during the solar maximum year of 2000 were rotating. Here we extend the study to include halo coronal mass ejections (CMEs) observed by SOHO/LASCO, of which 80% are associated with rotating sunspots and twisted magnetic flux tubes in 2000. Many of the CMEs, consisting of very energetic particles normally captured within a magnetic cloud of twisted flux tubes, accelerate out into the heliosphere where the Earth and its magnetic fields can encounter them, causing large geomagnetic events, such as geomagnetic storms, Solar Particle Events (SPEs), and other space weather effects. The amount of twist, or helicity, and its directionality may play important roles in solar eruptions and in the CME's interaction with the magnetosphere. Within the next year the Solar Dynamics Observatory (SDO) will launch and the HMI and AIA instruments will be available to observe the rotating sunspots and twisted magnetic flux tubes in greater detail than is currently being done to improve our understanding of these processes. Examples of such events and topological features will be shown and discussed with respect to the role that twisted magnetic flux

  5. The stretching of magnetic flux tubes in the convective overshoot region

    NASA Technical Reports Server (NTRS)

    Fisher, George H.; Mcclymont, Alexander N.; Chou, Dean-Yi

    1991-01-01

    The present study examines the fate of a magnetic flux tube initially lying at the bottom of the solar convective overshoot region. Stretching of the flux tube, e.g., by differential rotation, reduces its density, causing it to rise quasi-statically (a process referred to as vertical flux drift) until it reaches the top of the overshoot region and enters the buoyantly unstable convection region, from which a portion of it may ultimately protrude to form an active region on the surface. It is suggested that vertical flux drift and flux destabilization are inevitable consequences of field amplification, and it is surmised that these phenomena should be considered in self-consistent models of solar and stellar dynamos operating in the overshoot region.

  6. The stretching of magnetic flux tubes in the convective overshoot region

    NASA Technical Reports Server (NTRS)

    Fisher, George H.; Mcclymont, Alexander N.; Chou, Dean-Yi

    1991-01-01

    The present study examines the fate of a magnetic flux tube initially lying at the bottom of the solar convective overshoot region. Stretching of the flux tube, e.g., by differential rotation, reduces its density, causing it to rise quasi-statically (a process referred to as vertical flux drift) until it reaches the top of the overshoot region and enters the buoyantly unstable convection region, from which a portion of it may ultimately protrude to form an active region on the surface. It is suggested that vertical flux drift and flux destabilization are inevitable consequences of field amplification, and it is surmised that these phenomena should be considered in self-consistent models of solar and stellar dynamos operating in the overshoot region.

  7. Laboratory Measurement of 3D Magnetic Reconnection of Arched Flux Tubes

    NASA Astrophysics Data System (ADS)

    Haw, Magnus; Bellan, Paul M.

    2015-11-01

    An experiment has been constructed to collide two arched magnetic flux tubes at different angles with fully 3D, non-symmetric geometry. The configuration is designed to mimic sheared solar arcades and evaluate the importance of magnetic reconnection in such systems. Time resolved (1MHz) 3D magnetic measurements are taken with a multi-channel 3D magnetic probe. Preliminary analysis shows good agreement between calculated current density and external current diagnostics. Additional simultaneous diagnostics include voltage probes, fast camera imaging, and a 12-channel spectrometer. The spectrometer measures temperature, density, velocity, while the camera provides a view of global plasma behavior. Fast camera images indicate that the topology of the flux tubes evolves such that two equally sized, overlapping loops reconnect to form a small underlying loop and a large overarching loop.

  8. Propagation of Long-Wavelength Nonlinear Slow Sausage Waves in Stratified Magnetic Flux Tubes

    NASA Astrophysics Data System (ADS)

    Barbulescu, M.; Erdélyi, R.

    2016-05-01

    The propagation of nonlinear, long-wavelength, slow sausage waves in an expanding magnetic flux tube, embedded in a non-magnetic stratified environment, is discussed. The governing equation for surface waves, which is akin to the Leibovich-Roberts equation, is derived using the method of multiple scales. The solitary wave solution of the equation is obtained numerically. The results obtained are illustrative of a solitary wave whose properties are highly dependent on the degree of stratification.

  9. Plasma dynamics on current-carrying magnetic flux tubes. II - Low potential simulation

    NASA Technical Reports Server (NTRS)

    Swift, Daniel W.

    1992-01-01

    The evolution of plasma in a current-carrying magnetic flux tube of variable cross section is investigated using a one-dimensional numerical simulation. The flux tube is narrow at the two ends and broad in the middle. The middle part of the flux tube is loaded with a hot, magnetically trapped population, and the two ends have a more dense, gravitationally bound population. A potential difference larger than the gravitational potential but less than the energy of the hot population is applied across the domain. The general result is that the potential change becomes distributed along the anode half of the domain, with negligible potential change on the cathode half. The potential is supported by the mirror force of magnetically trapped particles. The simulations show a steady depletion of plasma on the anode side of the flux tube. The current steadily decreases on a time scale of an ion transit time. The results may provide an explanation for the observed plasma depletions on auroral field lines carrying upward currents.

  10. Magnetic Reconnection in a Solar Eruption -Formation of the Flux Tube and its Eruption-

    NASA Astrophysics Data System (ADS)

    Inoue, Satoshi; Büchner, Jörg

    2016-07-01

    A solar eruption is one of a dramatic phenomenon observed in the solar corona. The flux tube, which is a bundle of highly twisted lines, is widely believed as a driver source of the eruption. Although the magnetic reconnection is a key process of the formation of the flux tube as well as the eruptive process, these dynamics are still open to be solved. In order to clarify these dynamics, we first perform a magnetohydrodynamic (MHD) simulation using a force-free field extrapolated from the photospheric magnetic field. Our simulation successfully produced the typical eruptive processes in which the twisted flux tube slowly ascends in the beginning of the eruption; afterwards, it shows the fast ascending. We found that the reconnection is a key process to break the force-free field initially constructed, and highly twisted flux tube formation during the slow rising phase and even after the fast eruption. Next we compare with Büchner + Skala simulations and compressively discuss the play of the reconnection in the solar eruption.

  11. PROPAGATION AND DISPERSION OF SAUSAGE WAVE TRAINS IN MAGNETIC FLUX TUBES

    SciTech Connect

    Oliver, R.; Terradas, J.; Ruderman, M. S.

    2015-06-10

    A localized perturbation of a magnetic flux tube produces wave trains that disperse as they propagate along the tube, where the extent of dispersion depends on the physical properties of the magnetic structure, on the length of the initial excitation, and on its nature (e.g., transverse or axisymmetric). In Oliver et al. we considered a transverse initial perturbation, whereas the temporal evolution of an axisymmetric one is examined here. In both papers we use a method based on Fourier integrals to solve the initial value problem. We find that the propagating wave train undergoes stronger attenuation for longer axisymmetric (or shorter transverse) perturbations, while the internal to external density ratio has a smaller effect on the attenuation. Moreover, for parameter values typical of coronal loops axisymmetric (transverse) wave trains travel at a speed 0.75–1 (1.2) times the Alfvén speed of the magnetic tube. In both cases, the wave train passage at a fixed position of the magnetic tube gives rise to oscillations with periods of the order of seconds, with axisymmetric disturbances causing more oscillations than transverse ones. To test the detectability of propagating transverse or axisymmetric wave packets in magnetic tubes of the solar atmosphere (e.g., coronal loops, spicules, or prominence threads) a forward modeling of the perturbations must be carried out.

  12. Propagation and Dispersion of Sausage Wave Trains in Magnetic Flux Tubes

    NASA Astrophysics Data System (ADS)

    Oliver, R.; Ruderman, M. S.; Terradas, J.

    2015-06-01

    A localized perturbation of a magnetic flux tube produces wave trains that disperse as they propagate along the tube, where the extent of dispersion depends on the physical properties of the magnetic structure, on the length of the initial excitation, and on its nature (e.g., transverse or axisymmetric). In Oliver et al. we considered a transverse initial perturbation, whereas the temporal evolution of an axisymmetric one is examined here. In both papers we use a method based on Fourier integrals to solve the initial value problem. We find that the propagating wave train undergoes stronger attenuation for longer axisymmetric (or shorter transverse) perturbations, while the internal to external density ratio has a smaller effect on the attenuation. Moreover, for parameter values typical of coronal loops axisymmetric (transverse) wave trains travel at a speed 0.75-1 (1.2) times the Alfvén speed of the magnetic tube. In both cases, the wave train passage at a fixed position of the magnetic tube gives rise to oscillations with periods of the order of seconds, with axisymmetric disturbances causing more oscillations than transverse ones. To test the detectability of propagating transverse or axisymmetric wave packets in magnetic tubes of the solar atmosphere (e.g., coronal loops, spicules, or prominence threads) a forward modeling of the perturbations must be carried out.

  13. Numerical simulation of filling a magnetic flux tube with a cold plasma: Anomalous plasma effects

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Leung, W. C.

    1995-01-01

    Large-scale models of plasmaspheric refilling have revealed that during the early stage of the refilling counterstreaming ion beams are a common feature. However, the instability of such ion beams and its effect on refilling remain unexplored. In order to learn the basic effects of ion beam instabilities on refilling, we have performed numerical simulations of the refilling of an artificial magnetic flux tube. (The shape and size of the tube are assumed so that the essential features of the refilling problem are kept in the simulation and at the same time the small scale processes driven by the ion beams are sufficiently resolved.) We have also studied the effect of commonly found equatorially trapped warm and/or hot plasma on the filling of a flux tube with a cold plasma. Three types of simulation runs have been performed.

  14. Numerical study of magnetic reconnection in merging flux tubes

    NASA Astrophysics Data System (ADS)

    Breslau, Joshua Adam

    2001-09-01

    A comprehensive 2D numerical study of magnetic reconnection in merging magnetic islands has been conducted using a new parallel resistive MHD/two-fluid code developed for the purpose. The code's variable resolution and parallel scalability make it possible to resolve both the narrow reconnection boundary layer and the global plasma, and to follow the evolution of both from triple-island to single-island equilibrium. An initial resistive MHD study showed slow reconnection in strong agreement with the Sweet-Parker model. Subsequent studies were conducted to compare two proposed mechanisms for increasing the reconnection rate: anomalous localized enhanced resistivity and two-fluid effects, which enter the fluid equations via the Hall term in Ohm's law. Both anomalous resistivity and the Hall term showed a clear tendency to increase the reconnection rate significantly and to eliminate its dependence on the resistivity. In both cases, this effect is associated with a broadening of the toroidal current sheet and consequently with an opening of the angle of the X-point at the field null. These faster reconnection rates are in better agreement with observational and experimental data.

  15. Fast Solar Wind from Slowly Expanding Magnetic Flux Tubes (P54)

    NASA Astrophysics Data System (ADS)

    Srivastava, A. K.; Dwivedi, B. N.

    2006-11-01

    aks.astro.itbhu@gmail.com We present an empirical model of the fast solar wind, emanating from radially oriented slowly expanding magnetic flux tubes. We consider a single-fluid, steady state model in which the flow is driven by thermal and non-thermal pressure gradients. We apply a non-Alfvénic energy correction at the coronal base and find that specific relations correlate solar wind speed and non-thermal energy flux with the aerial expansion factor. The results are compared with the previously reported ones.

  16. FULLY RESOLVED QUIET-SUN MAGNETIC FLUX TUBE OBSERVED WITH THE SUNRISE/IMAX INSTRUMENT

    SciTech Connect

    Lagg, A.; Solanki, S. K.; Riethmueller, T. L.; Schuessler, M.; Hirzberger, J.; Feller, A.; Borrero, J. M.; Barthol, P.; Gandorfer, A.; MartInez Pillet, V.; Bonet, J. A.; Del Toro Iniesta, J. C.; Domingo, V.; Knoelker, M.; Title, A. M.

    2010-11-10

    Until today, the small size of magnetic elements in quiet-Sun areas has required the application of indirect methods, such as the line-ratio technique or multi-component inversions, to infer their physical properties. A consistent match to the observed Stokes profiles could only be obtained by introducing a magnetic filling factor that specifies the fraction of the observed pixel filled with magnetic field. Here, we investigate the properties of a small magnetic patch in the quiet Sun observed with the IMaX magnetograph on board the balloon-borne telescope SUNRISE with unprecedented spatial resolution and low instrumental stray light. We apply an inversion technique based on the numerical solution of the radiative transfer equation to retrieve the temperature stratification and the field strength in the magnetic patch. The observations can be well reproduced with a one-component, fully magnetized atmosphere with a field strength exceeding 1 kG and a significantly enhanced temperature in the mid to upper photosphere with respect to its surroundings, consistent with semi-empirical flux tube models for plage regions. We therefore conclude that, within the framework of a simple atmospheric model, the IMaX measurements resolve the observed quiet-Sun flux tube.

  17. Distortions of Magnetic Flux Tubes in the Presence of Electric Currents

    NASA Astrophysics Data System (ADS)

    Malanushenko, Anna; Rempel, Matthias; Cheung, Mark

    2016-05-01

    Solar coronal loops possess several peculiar properties, which have been a subject of intensive research for a long time. These in particular include the lack of apparent expansion of coronal loops and the increased pressure scale height in loops compared to the diffuse background. Previously, Malanushenko & Schrijver (2013) proposed that these could be explained by the fact that magnetic flux tubes expand with height in a highly anisotropic manner. They used potential field models to demonstrate that flux tubes that have circular cross section at the photosphere, in the corona turn into a highly elongates structures, more resembling thick ribbons. Such ribbons, viewed along the expanding edge, would appear as thin, crisp structures of a constant cross-section with an increased pressure scale height, and when viewed along the non-expanding side, would appear as faint, wide and underdense features. This may also introduce a selection bias,when a set of loops is collected for a further study, towards those viewed along the expanding edge.However, some of the past studies have indicated that strong electric currents flowing in a given flux tube may result in the tube maintaining a relatively constant cross-sectional shape along its length. Given that Malanushenko & Schrijver (2013) focused on a potential, or current-free, field model of an active region, the extend to which their analysis could be applied to the real solar fields, was unclear.In the present study, we use a magnetic field created by MURaM, a highly realistic state-of-the-art radiative MHD code (Vogler et al, 2005; Rempel et al, 2009b). MURaM was shown to reproduce a wide variety of observed features of the solar corona (e.g., Hansteen et al, 2010; Cheung et al. 2007, 2008; Rempel 2009a,b). We analyze the distortions of magnetic flux tubes in a MURaM simulation of an active region corona. We quantify such distortions and correlate them with a number of relevant parameters of flux tubes, with a

  18. P-mode induced convective collapse in vertical expanding magnetic flux tubes?

    NASA Astrophysics Data System (ADS)

    Utz, D.; van Doorsselaere, T.; Magyar, N.; Bárta, M.; Campos Rozo, J. I.

    2017-10-01

    Small-scale kG strong magnetic field elements in the solar photosphere are often identified as so-called magnetic bright points (MBPs). In principle these MBPs represent the cross-section of a vertical, strong, magnetic flux tube which is expanding with height in the solar atmosphere. As these magnetic elements represent possible MHD wave guides, a significant interest has been already paid to them from the viewpoint of observations and simulations. In this work we would like to shed more light on a possible scenario for the creation of such strong magnetic field concentrations. The accepted standard scenario involves the convective collapse process. In this ongoing work we will show indications that this convective collapse process may become triggered by sufficiently strong pressure disturbances. However, it is highly unlikely that p-mode waves can be of such a strength.

  19. Signature of collision of magnetic flux tubes in the quiet solar photosphere

    NASA Astrophysics Data System (ADS)

    Andic, Aleksandra

    2011-08-01

    Collision of the magnetic flux tubes in the Quiet Sun was proposed as one of the possible sources for the heating of the solar atmosphere (Furusawa and Sakai, 2000). The solar photosphere was observed using the New Solar Telescope ad Big Bear Solar Observatory. In TiO spectral line at 705.68 nm we approached resolution of 0.1''. The horizontal plasma wave was observed spreading from the larger bright point. Shorty after this wave an increase in the oscillatory power appeared at the same location as the observed bright point. This behavior matches some of the results from the simulation of the collision of the two flux tubes with a weak current.

  20. KELVIN-HELMHOLTZ INSTABILITY IN CORONAL MAGNETIC FLUX TUBES DUE TO AZIMUTHAL SHEAR FLOWS

    SciTech Connect

    Soler, R.; Terradas, J.; Oliver, R.; Ballester, J. L.; Goossens, M.

    2010-04-01

    Transverse oscillations of coronal loops are often observed and have been theoretically interpreted as kink magnetohydrodynamic (MHD) modes. Numerical simulations by Terradas et al. suggest that shear flows generated at the loop boundary during kink oscillations could give rise to a Kelvin-Helmholtz instability (KHI). Here, we investigate the linear stage of the KHI in a cylindrical magnetic flux tube in the presence of azimuthal shear motions. We consider the basic, linearized MHD equations in the beta = 0 approximation and apply them to a straight and homogeneous cylindrical flux tube model embedded in a coronal environment. Azimuthal shear flows with a sharp jump of the velocity at the cylinder boundary are included in the model. We obtain an analytical expression for the dispersion relation of the unstable MHD modes supported by the configuration, and compute analytical approximations of the critical velocity shear and the KHI growth rate in the thin tube limit. A parametric study of the KHI growth rates is performed by numerically solving the full dispersion relation. We find that fluting-like modes can develop a KHI in timescales comparable to the period of kink oscillations of the flux tube. The KHI growth rates increase with the value of the azimuthal wavenumber and decrease with the longitudinal wavenumber. However, the presence of a small azimuthal component of the magnetic field can suppress the KHI. Azimuthal motions related to kink oscillations of untwisted coronal loops may trigger a KHI, but this phenomenon has not been observed to date. We propose that the azimuthal component of the magnetic field is responsible for suppressing the KHI in a stable coronal loop. The required twist is small enough to prevent the development of the pinch instability.

  1. Peculiarities of Alfven wave propagation along a nonuniform magnetic flux tube

    SciTech Connect

    Erkaev, N.V.; Shaidurov, V.A.; Semenov, V.S.; Langmayr, D.; Biernat, H.K.

    2005-01-01

    Within the framework of the assumption of large azimuthal wave numbers, the equations for Alfven and slow magnetosonic waves are obtained using frozen-in material coordinates. These equations are specified for the case of a nonuniform magnetic field with axial symmetry. Assuming a meridional polarization of the magnetic field and velocity perturbations, the effects of Alfven wave propagation are analyzed which are related to geometric characteristics of a nonuniform magnetic field: (a) A finite curvature radius of the magnetic field lines and (b) convergence of magnetic field lines. The interaction between the Alfven and magnetosonic waves is found to be strongly dependent on the curvature radius of the magnetic tube and the local plasma {beta} parameter. The electric field amplitude and the length scale of a wave front are found to increase very strongly in the course of the Alfven wave propagation along a converging magnetic flux tube. Also studied is a temporal decrease of the wave perturbations which is caused by dissipation at the conducting boundary.

  2. The deformation of flux tubes in the solar wind with applications to the structure of magnetic clouds and CMEs

    NASA Technical Reports Server (NTRS)

    Cargill, Peter J.; Chen, James; Spicer, D. S.; Zalesak, S. T.

    1994-01-01

    Two dimensional magnetohydrodynamic simulations of the distortion of a magnetic flux tube, accelerated through ambient solar wind plasma, are presented. Vortices form on the trailing edge of the flux tube, and couple strongly to its interior. If the flux tube azimuthal field is weak, it deforms into an elongated banana-like shape after a few Alfven transit times. A significant azimuthal field component inhibits this distortion. In the case of magnetic clouds in the solar wind, it is suggested that the shape observed at 1 AU was determined by distortion of the cloud in the inner heliosphere. Distortion of the cloud beyond 1 AU takes many days. It is estimated that effective drag coefficients slightly greater than unity are appropriate for modeling flux tube propagation. Synthetic magnetic field profiles as would be seen by a spacecraft traversing the cloud are presented.

  3. First Reconnected Flux Tubes

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Lapenta, G.; Newman, D. L.; Markidis, S.; Spanswick, E. L.; Baker, J. B.; Clausen, L. B.; Larson, D. E.; Ergun, R. E.; Frey, H. U.; Singer, H. J.; Angelopoulos, V.; Bonnell, J. W.; McFadden, J. P.; Glassmeier, K.; Wolfgang, B.

    2011-12-01

    THEMIS observations from the magnetic equator (the equatorial plane) in the near-earth tail reveal a great amount of information regarding the plasma environment in the vicinity of the first reconnected flux tubes (a subgroup of dipolarization fronts). Two sequential observations of dipolarization fronts are analyzed in detail using three of the THEMIS spacecraft. Particle acceleration to high energies (>50 keV) is observed together with a void region interpreted as a region to which the full electron distribution has incomplete access. Whistler waves, which are observed, could be driven by one of the two electron populations located in the wake of the first reconnected flux tubes. The detailed observations are compared with 2D and 3D implicit kinetic simulation of reconnection events. This presentation focuses on the similarity between observation and simulation. One key aspect of this presentation is a demonstration of how different the signature is when observing at vs off the magnetic equator, since most observations in the literature (unlike the observations presented here) are from off the equator. For this event, additional spacecraft and ground observations have been analyzed, which demonstrate that a reconfiguration of the magnetosphere is taking place. However, the focus of this presentation is on the small scale (<~10 di), rather than the large scale (~20 Re).

  4. The model of self-sustained propagation of a magnetic reconnection along the flux tube

    NASA Astrophysics Data System (ADS)

    Dumin, Yurii

    This work represents a further development of our earlier ideas about heating the solar corona in the transition region from the "induction" to "drift" freezing of the magnetic field in plasma [1, 2]. The new detailed study of this process in the magnetic tube filled with a weakly-ionized plasma of the lower solar atmosphere shows that ignition of the magnetic reconnection develops most efficiently at the spot of approximate equality between the gyro-and collisional frequencies of charged particles. Next, due to the heat release and its propagation along the magnetic flux tube, the spot of most efficient reconnection moves upwards, thereby producing a self-sustained propagation of the reconnection along the field lines. The temperature increases sharply with height just due to decrease in plasma density, stratified by the gravitational field. This phenomenon may be efficiently applied to model the solar microflares, which are believed now to be an important ingredient of the solar atmosphere heating. References: 1. Yu.V. Dumin. Can Heating of the Solar Corona Be Related to a Transition from the In-duction to Drift Mechanism of the Magnetic Field Freezing in Plasma? Advances in Space Research, v.30, p.565 (2002). 2. Yu.V. Dumin. On the Physical Nature of the Magnetic-Field Freezing-in Effect in Collision-less Cosmic Plasmas. Solar System Research, v.32, p.323 (1998).

  5. The dynamic evolution of active-region-scale magnetic flux tubes in the turbulent solar convective envelope

    NASA Astrophysics Data System (ADS)

    Weber, Maria Ann

    2014-12-01

    The Sun exhibits cyclic properties of its large-scale magnetic field on the order of sigma22 years, with a ˜11 year frequency of sunspot occurrence. These sunspots, or active regions, are the centers of magnetically driven phenomena such as flares and coronal mass ejections. Volatile solar magnetic events directed toward the Earth pose a threat to human activities and our increasingly technological society. As such, the origin and nature of solar magnetic flux emergence is a topic of global concern. Sunspots are observable manifestations of solar magnetic fields, thus providing a photospheric link to the deep-seated dynamo mechanism. However, the manner by which bundles of magnetic field, or flux tubes, traverse the convection zone to eventual emergence at the solar surface is not well understood. To provide a connection between dynamo-generated magnetic fields and sunspots, I have performed simulations of magnetic flux emergence through the bulk of a turbulent, solar convective envelope by employing a thin flux tube model subject to interaction with flows taken from a hydrodynamic convection simulation computed through the Anelastic Spherical Harmonic (ASH) code. The convective velocity field interacts with the flux tube through the drag force it experiences as it traverses through the convecting medium. Through performing these simulations, much insight has been gained about the influence of turbulent solar-like convection on the flux emergence process and resulting active region properties. I find that the dynamic evolution of flux tubes change from convection dominated to magnetic buoyancy dominated as the initial field strength of the flux tubes increases from 15 kG to 100 kG. Additionally, active-region-scale flux tubes of 40 kG and greater exhibit properties similar to those of active regions on the Sun, such as: tilt angles, rotation rates, and morphological asymmetries. The joint effect of the Coriolis force and helical motions present in convective

  6. Observations on Characterization of Defects in Coiled Tubing From Magnetic-Flux-Leakage Data

    SciTech Connect

    Timothy R. McJunkin; Karen S. Miller; Charles R. Tolle

    2006-04-01

    This paper presents observations on the sizing of automatically detected artificial flaws in coiled tubing samples using magnetic-flux-leakage data. Sixty-six artificial flaws of various shapes and types, ranging from 0.30 mm deep pits to slots with length of 9.5 mm, in 44.45 mm outer diameter pipe were analyzed. The detection algorithm and the information automatically extracted from the data are described. Observations on the capabilities and limitations for determining the size and shape of the flaws are discussed.

  7. The motion of magnetic flux tube at the dayside magnetopause under the influence of solar wind flow

    SciTech Connect

    Liu, Z.X.; Hu, Y.D.; Li, F. ); Pu, Z.Y. )

    1990-05-01

    The authors propose that flux transfer events (FTEs) at the dayside magnetopause are formed by fluid vortices in the flow field. According to the view of vortex-induced reconnection a FTE tube is a magnetic fluid vortex tube (MF vortex tube). The motion of a FTE tube can be represented by that of a MF vortex in the formation region located in the dayside magnetopause region. This study deals with the internal and external influences governing the motion of MF vortex tubes. The equations of motion of a vortex tube are established and solved. It is found that a FTE tube moves frm low latitude to high latitude with a certain speed. However, the motional path is not a straight line but oscillates about the northward direction for the northern hemisphere. The motional velocity, amplitude and period of the oscillation depend on the flow field and magnetic field in the magnetosheath and magnetosphere as well as the size of the FTE tube.

  8. Sunspots and the physics of magnetic flux tubes. III - Aerodynamic lift

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1979-01-01

    The aerodynamic lift exerted on a magnetic flux tube by the asymmetric flow around the two sides of the tube is calculated as part of an investigation of the physics of solar flux tubes. The general hydrodynamic forces on a rigid circular cylinder in a nonuniform flow of an ideal fluid are derived from the first derivatives of the velocity field. Aerodynamic lift in a radial nonuniform flow is found to act in the direction of the flow, toward the region of increased flow velocity, while in a shear flow, lift is perpendicular to the free stream and directed toward increasing flow velocity. For a general, three dimensional, large-scale stationary incompressible equilibrium flow, an expression is also derived relating the lift per unit length to the dynamical pressure, cylinder radius and the gradient of the free-stream velocity. Evidence from an asymmetric airfoil in a uniform flow indicates that lift is enhanced in a real fluid in the presence of turbulence.

  9. Nonlinear Torsional and Compressional Waves in a Magnetic Flux Tube with Electric Current near the Quiet Solar Photospheric Network

    NASA Astrophysics Data System (ADS)

    Sakai, J. I.; Minamizuka, R.; Kawata, T.; Cramer, N. F.

    2001-04-01

    Recent high-resolution observations from photospheric magnetograms made with the SOHO/Michelson Doppler Imager instrument and the Swedish Vacuum Solar Telescope on La Palma showed that magnetic flux tubes in the quiet photospheric network of the solar photosphere are highly dynamic objects with small-scale substructures. We investigate nonlinear waves propagating along a magnetic flux tube in weakly ionized plasmas with high plasma beta (β~=1) by using three-dimensional neutral MHD equations. Recently Sakai et al. investigated nonlinear wave propagation along a magnetic flux tube with a weak current for the two cases of uniform density along the flux tube and density inhomogeneity due to solar gravity. They showed that shear Alfvén waves are excited by localized, predominantly rotational perturbations and that excited waves with a strong upflow of wave energy can propagate only upward along the flux tube when density inhomogeneity due to gravity is taken into account. In this paper we extend this work by investigating nonlinear torsional and compressional waves in a magnetic flux tube with a strong electric current, i.e., a twisted magnetic field, near the quiet solar photospheric network. If gravity is neglected, the torsional waves are found to propagate in a direction such as to decrease the twist of the magnetic field, while the compressional waves propagate symmetrically. We have found that solar gravity results in the important effect that wave energies excited by both torsional and compressional disturbances can be transferred upward in both untwisted and highly twisted flux tubes and eventually contribute to coronal heating.

  10. Plasmaspheric filament: an isolated magnetic flux tube filled with dense plasmas

    NASA Astrophysics Data System (ADS)

    Murakami, Go; Yoshikawa, Ichiro; Yoshioka, Kazuo; Yamazaki, Atsushi; Kagitani, Masato; Taguchi, Makoto; Kikuchi, Masayuki; Kameda, Shingo; Nakamura, Masato

    2013-01-01

    Abstract<p label="1">The Telescope of Extreme Ultraviolet (TEX) onboard Japan's lunar orbiter KAGUYA provided the first sequential images of the Earth's plasmasphere from the "side" (meridian) view. The TEX instrument obtained the global distribution of the terrestrial helium ions (He+) by detecting resonantly scattered emission at 30.4 nm. One of the most striking features of the plasmasphere found by TEX is an arc-shaped structure of enhanced brightness, which we call a "plasmaspheric filament". In the TEX image on 2 June 2008, the filament structure was clearly aligned to the dipole <span class="hlt">magnetic</span> field line of L = 3.7 at 7.3 <span class="hlt">magnetic</span> local time. Our analysis suggests that the filament represents an isolated <span class="hlt">flux</span> <span class="hlt">tube</span> filled with four times higher He+ density than its neighbors. We found four events of plasmaspheric filament in the images obtained between March and June 2008, and in all four events, the geomagnetic activity was quite low. The plasmaspheric filament in the TEX image is the first evidence that a "finger" structure seen in the IMAGE-EUV image is the projection of an isolated <span class="hlt">flux</span> <span class="hlt">tube</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000ApJ...537.1063S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000ApJ...537.1063S"><span>Simulation of a Collision between Shock Waves and a <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span>: Excitation of Surface Alfvén Waves and Body Alfvén Waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sakai, J. I.; Kawata, T.; Yoshida, K.; Furusawa, K.; Cramer, N. F.</p> <p>2000-07-01</p> <p>To explain the observed dynamics of the small-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in the quiet photospheric network, Furusawa & Sakai presented simulation results on the collision of two <span class="hlt">flux</span> <span class="hlt">tubes</span>. They found that shock waves appear during the collision of two <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>, when two <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> with weak electric current collide with each other. The shock waves so generated can subsequently collide with another <span class="hlt">flux</span> <span class="hlt">tube</span>, and we investigate here the interaction process of the shock with the <span class="hlt">flux</span> <span class="hlt">tube</span>. It is found that during the collision of a shock wave with a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> with weak electric current, surface Alfvén waves can be generated and propagate along the <span class="hlt">flux</span> <span class="hlt">tube</span>. However, when the shock wave collides with a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> with strong current, body Alfvén waves can be generated and propagate along the <span class="hlt">flux</span> <span class="hlt">tube</span>. It is also shown that, when we take into account the effect of a background density inhomogeneity due to gravity, there occurs a strong upward plasma jet along the <span class="hlt">flux</span> <span class="hlt">tube</span>, as well as surface Alfvén waves. The energy conversion rate from the shock wave energy to the upward MHD waves, as well as upward plasma flows, is about 40% and thus is very efficient. We apply our results to the problem of solar coronal heating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890062607&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drotation%2Bmagnetic%2Bflux','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890062607&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drotation%2Bmagnetic%2Bflux"><span>Slow twists of solar <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> and the polar <span class="hlt">magnetic</span> field of the sun</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hollweg, Joseph V.; Lee, Martin A.</p> <p>1989-01-01</p> <p>The solar wind model of Weber and Davis (1967) is generalized to compute the heliospheric <span class="hlt">magnetic</span> field resulting from solar rotation or a steady axisymmetric twist including a geometrical expansion which is more rapid than spherical. The calculated increase in the ratio of the toroidal to poloidal field components with heliocentric radial distance r clarifies an expression derived recently by Jokipii and Kota (1989). <span class="hlt">Magnetic</span>-field components transverse to r do not in general grow to dominate the radial component at large r. The analysis also yields expressions for the Poynting <span class="hlt">flux</span> associated with the steady twists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22356484','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22356484"><span>Propagation and dispersion of transverse wave trains in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Oliver, R.; Terradas, J.; Ruderman, M. S.</p> <p>2014-07-01</p> <p>The dispersion of small-amplitude, impulsively excited wave trains propagating along a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> is investigated. The initial disturbance is a localized transverse displacement of the <span class="hlt">tube</span> that excites a fast kink wave packet. The spatial and temporal evolution of the perturbed variables (density, plasma displacement, velocity, ...) is given by an analytical expression containing an integral that is computed numerically. We find that the dispersion of fast kink wave trains is more important for shorter initial disturbances (i.e., more concentrated in the longitudinal direction) and for larger density ratios (i.e., for larger contrasts of the <span class="hlt">tube</span> density with respect to the environment density). This type of excitation generates a wave train whose signature at a fixed position along a coronal loop is a short event (duration ≅ 20 s) in which the velocity and density oscillate very rapidly with typical periods of the order of a few seconds. The oscillatory period is not constant but gradually declines during the course of this event. Peak values of the velocity are of the order of 10 km s{sup –1} and are accompanied by maximum density variations of the order of 10%-15% the unperturbed loop density.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PASJ...69....5M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PASJ...69....5M"><span>Structural properties of the solar flare-producing coronal current system developed in an emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Magara, Tetsuya</p> <p>2017-02-01</p> <p>The activity of a <span class="hlt">magnetic</span> structure formed in the solar corona depends on a coronal current system developed in the structure, which determines how an electric current flows in the corona. To investigate structural properties of the coronal current system responsible for producing a solar flare, we perform magnetohydrodynamic simulation of an emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> which forms a coronal <span class="hlt">magnetic</span> structure. Investigation using fractal dimensional analysis and electric current streamlines reveals that the flare-producing coronal current system relies on a specific coronal current structure of two-dimensional spatiality, which has a sub-region where a nearly anti-parallel <span class="hlt">magnetic</span> field configuration is spontaneously generated. We discuss the role of this locally generated anti-parallel <span class="hlt">magnetic</span> field configuration in causing the reconnection of a three-dimensional <span class="hlt">magnetic</span> field, which is a possible mechanism for producing a flare. We also discuss how the twist of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> affects structural properties of a coronal current system, showing how much volume current <span class="hlt">flux</span> is carried into the corona by an emerging <span class="hlt">flux</span> <span class="hlt">tube</span>. This gives a way to evaluate the activity of a coronal <span class="hlt">magnetic</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27554930','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27554930"><span><span class="hlt">Magnetic-flux</span>-driven topological quantum phase transition and manipulation of perfect edge states in graphene <span class="hlt">tube</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, S; Zhang, G; Li, C; Song, Z</p> <p>2016-08-24</p> <p>We study the tight-binding model for a graphene <span class="hlt">tube</span> with perimeter N threaded by a <span class="hlt">magnetic</span> field. We show exactly that this model has different nontrivial topological phases as the <span class="hlt">flux</span> changes. The winding number, as an indicator of topological quantum phase transition (QPT) fixes at N/3 if N/3 equals to its integer part [N/3], otherwise it jumps between [N/3] and [N/3] + 1 periodically as the <span class="hlt">flux</span> varies a <span class="hlt">flux</span> quantum. For an open <span class="hlt">tube</span> with zigzag boundary condition, exact edge states are obtained. There exist two perfect midgap edge states, in which the particle is completely located at the boundary, even for a <span class="hlt">tube</span> with finite length. The threading <span class="hlt">flux</span> can be employed to control the quantum states: transferring the perfect edge state from one end to the other, or generating maximal entanglement between them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4995410','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4995410"><span><span class="hlt">Magnetic-flux</span>-driven topological quantum phase transition and manipulation of perfect edge states in graphene <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lin, S.; Zhang, G.; Li, C.; Song, Z.</p> <p>2016-01-01</p> <p>We study the tight-binding model for a graphene <span class="hlt">tube</span> with perimeter N threaded by a <span class="hlt">magnetic</span> field. We show exactly that this model has different nontrivial topological phases as the <span class="hlt">flux</span> changes. The winding number, as an indicator of topological quantum phase transition (QPT) fixes at N/3 if N/3 equals to its integer part [N/3], otherwise it jumps between [N/3] and [N/3] + 1 periodically as the <span class="hlt">flux</span> varies a <span class="hlt">flux</span> quantum. For an open <span class="hlt">tube</span> with zigzag boundary condition, exact edge states are obtained. There exist two perfect midgap edge states, in which the particle is completely located at the boundary, even for a <span class="hlt">tube</span> with finite length. The threading <span class="hlt">flux</span> can be employed to control the quantum states: transferring the perfect edge state from one end to the other, or generating maximal entanglement between them. PMID:27554930</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950059820&hterms=dissipative&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddissipative','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950059820&hterms=dissipative&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddissipative"><span>Dissipative MHD solutions for resonant Alfven waves in 1-dimensional <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goossens, Marcel; Ruderman, Michail S.; Hollweg, Joseph V.</p> <p>1995-01-01</p> <p>The present paper extends the analysis by Sakurai, Goossens, and Hollweg (1991) on resonant Alfven waves in nonuniform <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. It proves that the fundamental conservation law for resonant Alfven waves found in ideal MHD by Sakurai, Goossens, and Hollweg remains valid in dissipative MHD. This guarantees that the jump conditions of Sakurai, Goossens, and Hollweg, that connect the ideal MHD solutions for xi(sub r), and P' across the dissipative layer, are correct. In addition, the present paper replaces the complicated dissipative MHD solutions obtained by Sakurai, Goossens, and Hollweg for xi(sub r), and P' in terms of double integrals of Hankel functions of complex argument of order 1/3 with compact analytical solutions that allow a straight- forward mathematical and physical interpretation. Finally, it presents an analytical dissipative MHD solution for the component of the Lagrangian displacement in the <span class="hlt">magnetic</span> surfaces perpen- dicular to the <span class="hlt">magnetic</span> field lines xi(sub perpendicular) which enables us to determine the dominant dynamics of resonant Alfven waves in dissipative MHD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...843...93C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...843...93C"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Rope Shredding By a Hyperbolic <span class="hlt">Flux</span> <span class="hlt">Tube</span>: The Detrimental Effects of <span class="hlt">Magnetic</span> Topology on Solar Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chintzoglou, Georgios; Vourlidas, Angelos; Savcheva, Antonia; Tassev, Svetlin; Tun Beltran, Samuel; Stenborg, Guillermo</p> <p>2017-07-01</p> <p>We present the analysis of an unusual failed eruption captured in high cadence and in many wavelengths during the observing campaign in support of the Very high Angular resolution Ultraviolet Telescope (VAULT2.0) sounding rocket launch. The refurbished VAULT2.0 is a Lyα (λ 1216 Å) spectroheliograph launched on 2014 September 30. The campaign targeted active region NOAA AR 12172 and was closely coordinated with the Hinode and IRIS missions and several ground-based observatories (NSO/IBIS, SOLIS, and BBSO). A filament eruption accompanied by a low-level flaring event (at the GOES C-class level) occurred around the VAULT2.0 launch. No coronal mass ejection was observed. The eruption and its source region, however, were recorded by the campaign instruments in many atmospheric heights ranging from the photosphere to the corona in high cadence and spatial resolution. This is a rare occasion that enabled us to perform a comprehensive investigation on a failed eruption. We find that a rising <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Rope (MFR)-like structure was destroyed during its interaction with the ambient <span class="hlt">magnetic</span> field, creating downflows of cool plasma and diffuse hot coronal structures reminiscent of “cusps.” We employ magnetofrictional simulations to show that the <span class="hlt">magnetic</span> topology of the ambient field is responsible for the destruction of the MFR. Our unique observations suggest that the <span class="hlt">magnetic</span> topology of the corona is a key ingredient for a successful eruption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22370207','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22370207"><span>On the area expansion of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in solar active regions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dudík, Jaroslav; Dzifčáková, Elena; Cirtain, Jonathan W. E-mail: elena@asu.cas.cz</p> <p>2014-11-20</p> <p>We calculated the three-dimensional (3D) distribution of the area expansion factors in a potential <span class="hlt">magnetic</span> field, extrapolated from the high-resolution Hinode/SOT magnetogram of the quiescent active region NOAA 11482. Retaining only closed loops within the computational box, we show that the distribution of area expansion factors show significant structure. Loop-like structures characterized by locally lower values of the expansion factor are embedded in a smooth background. These loop-like <span class="hlt">flux</span> <span class="hlt">tubes</span> have squashed cross-sections and expand with height. The distribution of the expansion factors show an overall increase with height, allowing an active region core characterized by low values of the expansion factor to be distinguished. The area expansion factors obtained from extrapolation of the Solar Optical Telescope magnetogram are compared to those obtained from an approximation of the observed magnetogram by a series of 134 submerged charges. This approximation retains the general <span class="hlt">flux</span> distribution in the observed magnetogram, but removes the small-scale structure in both the approximated magnetogram and the 3D distribution of the area expansion factors. We argue that the structuring of the expansion factor can be a significant ingredient in producing the observed structuring of the solar corona. However, due to the potential approximation used, these results may not be applicable to loops exhibiting twist or to active regions producing significant flares.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ascl.soft05008S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ascl.soft05008S"><span><span class="hlt">Flux</span> <span class="hlt">Tube</span> Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Steiner, O.</p> <p>2011-05-01</p> <p>This Fortran code computes magnetohydrostatic <span class="hlt">flux</span> <span class="hlt">tubes</span> and sheets according to the method of Steiner, Pneuman, & Stenflo (1986) A&A 170, 126-137. The code has many parameters contained in one input file that are easily modified. Extensive documentation is provided in README files.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...791..129H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...791..129H"><span>The Scattering of f- and p-modes from Ensembles of Thin <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tubes</span>: An Analytical Approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hanson, Chris S.; Cally, Paul S.</p> <p>2014-08-01</p> <p>Motivated by the observational results of Braun, we extend the model of Hanson & Cally to address the effect of multiple scattering of f and p modes by an ensemble of thin vertical <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in the surface layers of the Sun. As in the observational Hankel analysis, we measure the scatter and phase shift from an incident cylindrical wave in a coordinate system roughly centered in the core of the ensemble. It is demonstrated that although thin <span class="hlt">flux</span> <span class="hlt">tubes</span> are unable to interact with high-order fluting modes individually, they can indirectly absorb energy from these waves through the scatters of kink and sausage components. It is also shown how the distribution of absorption and phase shift across the azimuthal order m depends strongly on the <span class="hlt">tube</span> position as well as on the individual <span class="hlt">tube</span> characteristics. This is the first analytical study into an ensembles multiple-scattering regime that is embedded within a stratified atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22365268','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22365268"><span>The scattering of f- and p-modes from ensembles of thin <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>: an analytical approach</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hanson, Chris S.; Cally, Paul S.</p> <p>2014-08-20</p> <p>Motivated by the observational results of Braun, we extend the model of Hanson and Cally to address the effect of multiple scattering of f and p modes by an ensemble of thin vertical <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in the surface layers of the Sun. As in the observational Hankel analysis, we measure the scatter and phase shift from an incident cylindrical wave in a coordinate system roughly centered in the core of the ensemble. It is demonstrated that although thin <span class="hlt">flux</span> <span class="hlt">tubes</span> are unable to interact with high-order fluting modes individually, they can indirectly absorb energy from these waves through the scatters of kink and sausage components. It is also shown how the distribution of absorption and phase shift across the azimuthal order m depends strongly on the <span class="hlt">tube</span> position as well as on the individual <span class="hlt">tube</span> characteristics. This is the first analytical study into an ensembles multiple-scattering regime that is embedded within a stratified atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPNO7001V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPNO7001V"><span>Investigating the Dynamics of Canonical <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von der Linden, Jens; Sears, Jason; Intrator, Thomas; You, Setthivoine</p> <p>2016-10-01</p> <p>Canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> are <span class="hlt">flux</span> <span class="hlt">tubes</span> of the circulation of a species' canonical momentum. They provide a convenient generalization of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> to regimes beyond magnetohydrodynamics (MHD). We hypothesize that hierarchies of instabilities which couple disparate scales could transfer <span class="hlt">magnetic</span> pitch into helical flows and vice versa while conserving the total canonical helicity. This work first explores the possibility of a sausage instability existing on top of a kink as mechanism for coupling scales, then presents the evolution of canonical helicity in a gyrating kinked <span class="hlt">flux</span> rope. Analytical and numerical stability spaces derived for <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> with core and skin currents indicate that, as a <span class="hlt">flux</span> <span class="hlt">tube</span> lengthens and collimates, it may become kink unstable with a sausage instability developing on top of the kink. A new analysis of 3D <span class="hlt">magnetic</span> field and ion flow data on gyrating kinked <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes from the Reconnection Scaling Experiment tracks the evolution of canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> and their helicity. These results and methodology are being developed as part of the Mochi experiment specifically designed to observe the dynamics of canonical <span class="hlt">flux</span> <span class="hlt">tubes</span>. This work is supported by DOE Grant DE-SC0010340 and the DOE Office of Science Graduate Student Research Program and prepared in part by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-697161.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940026637','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940026637"><span>Dynamics of <span class="hlt">flux</span> <span class="hlt">tubes</span> in accretion disks</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vishniac, E. T.; Duncan, R. C.</p> <p>1994-01-01</p> <p>The study of <span class="hlt">magnetized</span> plasmas in astrophysics is complicated by a number of factors, not the least of which is that in considering <span class="hlt">magnetic</span> fields in stars or accretion disks, we are considering plasmas with densities well above those we can study in the laboratory. In particular, whereas laboratory plasmas are dominated by the confining <span class="hlt">magnetic</span> field pressure, stars, and probably accretion disks, have <span class="hlt">magnetic</span> fields whose beta (ratio of gas pressure to <span class="hlt">magnetic</span> field pressure) is much greater than 1. Observations of the Sun suggest that under such circumstances the <span class="hlt">magnetic</span> field breaks apart into discrete <span class="hlt">flux</span> <span class="hlt">tubes</span> with a small filling factor. On the other hand, theoretical treatments of MHD turbulence in high-beta plasmas tend to assume that the field is more or less homogeneously distributed throughout the plasma. Here we consider a simple model for the distribution of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in a turbulent medium. We discuss the mechanism by which small inhomogeneities evolve into discrete <span class="hlt">flux</span> <span class="hlt">tubes</span> and the size and distribution of such <span class="hlt">flux</span> <span class="hlt">tubes</span>. We then apply the model to accretion disks. We find that the fibrilation of the <span class="hlt">magnetic</span> field does not enhance <span class="hlt">magnetic</span> buoyancy. We also note that the evolution of an initially diffuse field in a turbulent medium, e.g., any uniform field in a shearing flow, will initially show exponential growth as the <span class="hlt">flux</span> <span class="hlt">tubes</span> form. This growth saturates when the <span class="hlt">flux</span> <span class="hlt">tube</span> formation is complete and cannot be used as the basis for a self-sustaining dynamo effect. Since the typical state of the <span class="hlt">magnetic</span> field is a collection of intense <span class="hlt">flux</span> <span class="hlt">tubes</span>, this effect is of limited interest. However, it may be important early in the evolution of the galactic <span class="hlt">magnetic</span> field, and it will play a large role in numerical simulations. Finally, we note that the formation of <span class="hlt">flux</span> <span class="hlt">tubes</span> is an essential ingredient in any successful dynamo model for stars or accretion disks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPUP8063V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPUP8063V"><span>Investigating the Dynamics of Canonical <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von der Linden, Jens; Carroll, Evan; Kamikawa, Yu; Lavine, Eric; Vereen, Keon; You, Setthivoine</p> <p>2013-10-01</p> <p>Canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> are defined by tracing areas of constant <span class="hlt">magnetic</span> and fluid vorticity <span class="hlt">flux</span>. This poster will present the theory for canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> and current progress in the construction of an experiment designed to observe their evolution. In the zero flow limit, canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> are <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>, but in full form, present the distinct advantage of reconciling two-fluid plasma dynamics with familiar concepts of helicity, twists and linkages. The experiment and the DCON code will be used to investigate a new MHD stability criterion for sausage and kink modes in screw pinches that has been generalized to <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> with skin and core currents. Camera images and a 3D array of ˙ B probes will measure <span class="hlt">tube</span> aspect-ratio and ratio of current-to-<span class="hlt">magnetic</span> <span class="hlt">flux</span>, respectively, to trace these <span class="hlt">flux</span> <span class="hlt">tube</span> parameters in a stability space. The experiment's triple electrode planar gun is designed to generate azimuthal and axial flows. These diagnostics together with a 3D vector tomographic reconstruction of ion Doppler spectroscopy will be used to verify the theory of canonical helicity transport. This work was sponsored in part by the US DOE Grant DE-SC0010340.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...835...89S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...835...89S"><span>The Topology of Canonical <span class="hlt">Flux</span> <span class="hlt">Tubes</span> in Flared Jet Geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sander Lavine, Eric; You, Setthivoine</p> <p>2017-01-01</p> <p><span class="hlt">Magnetized</span> plasma jets are generally modeled as <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> filled with flowing plasma governed by magnetohydrodynamics (MHD). We outline here a more fundamental approach based on <span class="hlt">flux</span> <span class="hlt">tubes</span> of canonical vorticity, where canonical vorticity is defined as the circulation of the species’ canonical momentum. This approach extends the concept of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> evolution to include the effects of finite particle momentum and enables visualization of the topology of plasma jets in regimes beyond MHD. A flared, current-carrying <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> in an ion-electron plasma with finite ion momentum is thus equivalent to either a pair of electron and ion flow <span class="hlt">flux</span> <span class="hlt">tubes</span>, a pair of electron and ion canonical momentum <span class="hlt">flux</span> <span class="hlt">tubes</span>, or a pair of electron and ion canonical vorticity <span class="hlt">flux</span> <span class="hlt">tubes</span>. We examine the morphology of all these <span class="hlt">flux</span> <span class="hlt">tubes</span> for increasing electrical currents, different radial current profiles, different electron Mach numbers, and a fixed, flared, axisymmetric <span class="hlt">magnetic</span> geometry. Calculations of gauge-invariant relative canonical helicities track the evolution of <span class="hlt">magnetic</span>, cross, and kinetic helicities in the system, and show that ion flow fields can unwind to compensate for an increasing <span class="hlt">magnetic</span> twist. The results demonstrate that including a species’ finite momentum can result in a very long collimated canonical vorticity <span class="hlt">flux</span> <span class="hlt">tube</span> even if the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> is flared. With finite momentum, particle density gradients must be normal to canonical vorticities, not to <span class="hlt">magnetic</span> fields, so observations of collimated astrophysical jets could be images of canonical vorticity <span class="hlt">flux</span> <span class="hlt">tubes</span> instead of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860049331&hterms=LTE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DLTE','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860049331&hterms=LTE&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DLTE"><span>On magnetohydrodynamic thermal instabilities in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. [in plane parallel stellar atmosphere in LTE and hydrostatic equilibrium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Massaglia, S.; Ferrari, A.; Bodo, G.; Kalkofen, W.; Rosner, R.</p> <p>1985-01-01</p> <p>The stability of current-driven filamentary modes in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> embedded in a plane-parallel atmosphere in LTE and in hydrostatic equilibrium is discussed. Within the <span class="hlt">tube</span>, energy transport by radiation only is considered. The dominant contribution to the opacity is due to H- ions and H atoms (in the Paschen continuum). A region in the parameter space of the equilibrium configuration in which the instability is effective is delimited, and the relevance of this process for the formation of structured coronae in late-type stars and accretion disks is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790057332&hterms=magnetic+lift&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagnetic%2Blift','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790057332&hterms=magnetic+lift&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagnetic%2Blift"><span>Sunspots and the physics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. IV - Aerodynamic lift on a thin cylinder in convective flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tsinganos, K. C.</p> <p>1979-01-01</p> <p>The aerodynamic lift exerted on a long circular cylinder immersed in a convective flow pattern in an ideal fluid is calculated to establish the equilibrium position of the cylinder. The calculations establish the surprising result that the cylinder is pushed out the upwellings and the downdrafts of the convective cell, into a location midway between them. The implications for the intense <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in the convection beneath the surface of the sun are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSH23B1536N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSH23B1536N"><span>Measurements of TRACE 171A Twisting Coronal Loop Fans about a Twisted <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> Originating From Below the Photosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nightingale, R. W.; Ma, G.; Ji, E.</p> <p>2009-12-01</p> <p>In our previous studies of rotating sunspots about their umbral centers over the past decade, we have been measuring the rotation at the photosphere of the cross sections of large, twisted <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> passing through from below. Many such rotating sunspots have been found and reported in the literature and at earlier meetings [e.g., Brown et al., Sol. Phys. 216, 79, 2003; Yan et al., ApJ 682, L65, 2008; Nightingale et al., Fall AGU Mtg. 2007]. Here we are attempting to measure the rotation of 1 million degree K EUV loops seen in TRACE 171A images emerging from what may be a large 6000 deg K <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> (invisible at EUV), which may be the extension of the associated rotating sunspot up in the corona, for active region 9114 on August 8 - 10, 2000. These nonpotential EUV loops appear to be attached at their other end to nonrotating opposite polarity <span class="hlt">magnetic</span> <span class="hlt">flux</span> regions and also appear to be flipping around like a twisted jump rope that is attached to a wall at one end. In movies of these twisted coronal loop fans the rotation appears obvious, but is difficult to measure, because of the constant motion and change of intensity of the fans, which tend to obscure each other and the apparent <span class="hlt">tube</span> center. We will show movies over the 3 days of the twisted loop fans, and details and first results of our measurements, which appear to be similar to those previously found for the associated rotating sunspot down at the photosphere. We will discuss how the twisted <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> energizes the corona, carrying energy up from beneath the photosphere. This work was supported by NASA under the TRACE contract NAS5-38099.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990GMS....58.....R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990GMS....58.....R"><span>Physics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russell, C. T.; Priest, E. R.; Lee, L. C.</p> <p></p> <p>The present work encompasses papers on the structure, waves, and instabilities of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes (MFRs), photospheric <span class="hlt">flux</span> <span class="hlt">tubes</span> (PFTs), the structure and heating of coronal loops, solar prominences, coronal mass ejections and <span class="hlt">magnetic</span> clouds, <span class="hlt">flux</span> ropes in planetary ionospheres, the magnetopause, magnetospheric field-aligned currents and <span class="hlt">flux</span> <span class="hlt">tubes</span>, and the magnetotail. Attention is given to the equilibrium of MFRs, resistive instability, <span class="hlt">magnetic</span> reconnection and turbulence in current sheets, dynamical effects and energy transport in intense <span class="hlt">flux</span> <span class="hlt">tubes</span>, waves in solar PFTs, twisted <span class="hlt">flux</span> ropes in the solar corona, an electrodynamical model of solar flares, filament cooling and condensation in a sheared <span class="hlt">magnetic</span> field, the magnetopause, the generation of twisted MFRs during <span class="hlt">magnetic</span> reconnection, ionospheric <span class="hlt">flux</span> ropes above the South Pole, substorms and MFR structures, evidence for <span class="hlt">flux</span> ropes in the earth magnetotail, and MFRs in 3D MHD simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930034888&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drotation%2Bmagnetic%2Bflux','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930034888&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drotation%2Bmagnetic%2Bflux"><span>Evolution of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> in two-dimensional penetrative convection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jennings, R. L.; Brandenburg, A.; Nordlund, A.; Stein, R. F.</p> <p>1992-01-01</p> <p>Highly supercritical compressible convection is simulated in a two-dimensional domain in which the upper half is unstable to convection while the lower half is stably stratified. This configuration is an idealization of the layers near the base of the solar convection zone. Once the turbulent flow is well developed, a toroidal <span class="hlt">magnetic</span> field B sub tor is introduced to the stable layer. The field's evolution is governed by an advection-diffusion-type equation, and the Lorentz force does not significantly affect the flow. After many turnover times the field is stratified such that the absolute value of B sub tor/rho is approximately constant in the convective layer, where rho is density, while in the stable layer this ratio decreases linearly with depth. Consequently most of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> is stored in the overshoot layer. The inclusion of rotation leads to travelling waves which transport <span class="hlt">magnetic</span> <span class="hlt">flux</span> latitudinally in a manner reminiscent of the migrations seen during the solar cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930034888&hterms=Tor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DTor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930034888&hterms=Tor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DTor"><span>Evolution of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> in two-dimensional penetrative convection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jennings, R. L.; Brandenburg, A.; Nordlund, A.; Stein, R. F.</p> <p>1992-01-01</p> <p>Highly supercritical compressible convection is simulated in a two-dimensional domain in which the upper half is unstable to convection while the lower half is stably stratified. This configuration is an idealization of the layers near the base of the solar convection zone. Once the turbulent flow is well developed, a toroidal <span class="hlt">magnetic</span> field B sub tor is introduced to the stable layer. The field's evolution is governed by an advection-diffusion-type equation, and the Lorentz force does not significantly affect the flow. After many turnover times the field is stratified such that the absolute value of B sub tor/rho is approximately constant in the convective layer, where rho is density, while in the stable layer this ratio decreases linearly with depth. Consequently most of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> is stored in the overshoot layer. The inclusion of rotation leads to travelling waves which transport <span class="hlt">magnetic</span> <span class="hlt">flux</span> latitudinally in a manner reminiscent of the migrations seen during the solar cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996PhRvC..53..448A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996PhRvC..53..448A"><span>Charm production in <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguiar, C. E.; Kodama, T.; Nazareth, R. A. M. S.; Pech, G.</p> <p>1996-01-01</p> <p>We argue that the nonperturbative Schwinger mechanism may play an important role in the hadronic production of charm. We present a <span class="hlt">flux</span> <span class="hlt">tube</span> model which assumes that the colliding hadrons become color charged because of gluon exchange, and that a single nonelementary <span class="hlt">flux</span> <span class="hlt">tube</span> is built up as they recede. The strong chromoelectric field inside this <span class="hlt">tube</span> creates quark pairs (including charmed ones) and the ensuing color screening breaks the <span class="hlt">tube</span> into excited hadronic clusters. In their turn these clusters, or ``fireballs,'' decay statistically into the final hadrons. The model is able to account for the soft production of charmed, strange, and lighter hadrons within a unified framework.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830038291&hterms=Diamagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DDiamagnetic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830038291&hterms=Diamagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DDiamagnetic"><span>Diamagnetic force on a <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yeh, T.</p> <p>1983-01-01</p> <p>The diamagnetic force on a straight <span class="hlt">flux</span> <span class="hlt">tube</span> is elucidated. The case when the <span class="hlt">flux</span> <span class="hlt">tube</span> has a circular cross section is considered, and the result is generalized to the case of noncircular cross section. The result shows that when the external <span class="hlt">magnetic</span> field is uniform, the diamagnetic force is simply equal to the vector multiplication of the internal conduction current and the external <span class="hlt">magnetic</span> field. It is independent of the size and shape of the cross section of the <span class="hlt">flux</span> <span class="hlt">tube</span>. This is analogous to the Kutta-Joukowski theorem that the aerodynamic lift force is proportional to the vector multiplication of the unperturbed flow velocity and the circulation around the airfoil. When the external <span class="hlt">magnetic</span> field is nonuniform, the diamagnetic force has an additional contribution which is proportional to the gradient of <span class="hlt">magnetic</span> pressure and to the volume of the <span class="hlt">flux</span> <span class="hlt">tube</span>. The constant of proportionality, which is shown to be equal to two for a circular cross section, indicates the enhancement of the nonuniformity of the external <span class="hlt">magnetic</span> field in the vicinity of the periphery by the polarization current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790055642&hterms=aerodynamic+drag&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Daerodynamic%2Bdrag','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055642&hterms=aerodynamic+drag&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Daerodynamic%2Bdrag"><span>Sunspots and the physics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. I - The general nature of the sunspot. II - Aerodynamic drag</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parker, E. N.</p> <p>1979-01-01</p> <p>Analysis of the dynamical stability of a large <span class="hlt">flux</span> <span class="hlt">tube</span> suggests that the field of a sunspot must divide into many separate <span class="hlt">tubes</span> within the first 1000 km below the surface. Buoyancy of the Wilson depression at the visible surface and probably also a downdraft beneath the sunspot hold the separate <span class="hlt">tubes</span> in a loose cluster. Convective generation of Alfven waves, which are emitted preferentially downward, cools the <span class="hlt">tubes</span>. Aerodynamic drag on a slender <span class="hlt">flux</span> <span class="hlt">tube</span> stretched vertically across a convective cell is also studied. Since the drag is approximately proportional to the local kinetic energy density, the density stratification weights the drag in favor of the upper layers. Horizontal motions concentrated in the bottom of the convective cell may reverse this density effect. A downdraft of about two km/sec through the <span class="hlt">flux</span> <span class="hlt">tubes</span> beneath the sunspot is hypothesized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MNRAS.453.2982D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MNRAS.453.2982D"><span>Self-organized criticality in a two-dimensional cellular automaton model of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> with background flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dănilă, B.; Harko, T.; Mocanu, G.</p> <p>2015-11-01</p> <p>We investigate the transition to self-organized criticality in a two-dimensional model of a <span class="hlt">flux</span> <span class="hlt">tube</span> with a background flow. The <span class="hlt">magnetic</span> induction equation, represented by a partial differential equation with a stochastic source term, is discretized and implemented on a two-dimensional cellular automaton. The energy released by the automaton during one relaxation event is the <span class="hlt">magnetic</span> energy. As a result of the simulations, we obtain the time evolution of the energy release, of the system control parameter, of the event lifetime distribution and of the event size distribution, respectively, and we establish that a self-organized critical state is indeed reached by the system. Moreover, energetic initial impulses in the magnetohydrodynamic flow can lead to one-dimensional signatures in the <span class="hlt">magnetic</span> two-dimensional system, once the self-organized critical regime is established. The applications of the model for the study of gamma-ray bursts (GRBs) is briefly considered, and it is shown that some astrophysical parameters of the bursts, like the light curves, the maximum released energy and the number of peaks in the light curve can be reproduced and explained, at least on a qualitative level, by working in a framework in which the systems settles in a self-organized critical state via <span class="hlt">magnetic</span> reconnection processes in the <span class="hlt">magnetized</span> GRB fireball.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPB10107L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPB10107L"><span>The Topology of Canonical <span class="hlt">Flux</span> <span class="hlt">Tubes</span> in Flared Jet Geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lavine, Eric Sander; You, Setthivoine</p> <p>2016-10-01</p> <p><span class="hlt">Magnetized</span> plasma jets are generally modeled as <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> filled with flowing plasma governed by MHD. We outline here a more fundamental approach based on <span class="hlt">flux</span> <span class="hlt">tubes</span> of canonical vorticity. This approach extends the concept of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> evolution to include the effects of finite particle momentum and enables visualization of the topology of plasma jets in regimes beyond MHD. We examine the morphology of these canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> for increasing electrical currents, different radial current profiles, different electron Mach numbers, and a fixed, flared, dipole <span class="hlt">magnetic</span> field. Calculations of gauge-invariant relative canonical helicity track the evolution of <span class="hlt">magnetic</span>, cross, and kinetic helicities in the system and show that ion flow fields can unwind to compensate for increasing <span class="hlt">magnetic</span> twist. The results demonstrate that including a species' finite momentum can result in long, collimated canonical vorticity <span class="hlt">flux</span> <span class="hlt">tubes</span> even when the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> is flared. With finite momentum, particle density gradients must be normal to canonical vorticities not to <span class="hlt">magnetic</span> fields, so observations of collimated astrophysical jets could be images of canonical vorticity <span class="hlt">flux</span> <span class="hlt">tubes</span> instead of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. This work is supported by DOE Grant DE-SC0010340.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSM41E..04P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSM41E..04P"><span>How the Saturnian Magnetosphere Conserves <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Powell, R. L.; Wei, H.; Russell, C. T.; Arridge, C. S.; Dougherty, M. K.</p> <p>2012-12-01</p> <p>The magnetospheric dynamics at Saturn are driven by the centrifugal force of near co-rotating water group ions released at a rate of hundreds of kilograms per second by Saturn's moon Enceladus. The plasma is accelerated up to co-rotation speed by the magnetospheric <span class="hlt">magnetic</span> field coupled to the Saturnian ionosphere. The plasma is lost ultimately through the process of <span class="hlt">magnetic</span> reconnection in the tail. Conservation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> requires that plasma-depleted, "empty" <span class="hlt">flux</span> <span class="hlt">tubes</span> return <span class="hlt">magnetic</span> <span class="hlt">flux</span> to the inner magnetosphere. After completion of the initial inrush of the reconnected and largely emptied <span class="hlt">flux</span> <span class="hlt">tubes</span> inward of the reconnection point, the <span class="hlt">flux</span> <span class="hlt">tubes</span> face the outflowing plasma and must move inward against the flow. Observations of such <span class="hlt">flux</span> <span class="hlt">tubes</span> have been identified in the eight years of Cassini magnetometer data. The occurrence of these <span class="hlt">tubes</span> is observed at all local times indicating slow inward transport of the <span class="hlt">tubes</span> relative to the co-rotation speed. Depleted <span class="hlt">flux</span> <span class="hlt">tubes</span> observed in the equatorial region appear as an enhancement in the magnitude of the <span class="hlt">magnetic</span> field, whereas the same <span class="hlt">flux</span> <span class="hlt">tubes</span> observed at higher latitudes appear as decreased field strength. The difference in appearance of the low latitude and the high latitude <span class="hlt">tubes</span> is due to the plasma environment just outside the <span class="hlt">tube</span>. Warm low-density plasma fills the inside of the <span class="hlt">flux</span> <span class="hlt">tube</span> at all latitudes. This <span class="hlt">flux</span> <span class="hlt">tube</span> thus will expand in the less dense regions away from the <span class="hlt">magnetic</span> equator and will be observed as a decrease in the magnitude of the <span class="hlt">magnetic</span> field from the background. These <span class="hlt">flux</span> <span class="hlt">tubes</span> near the equator, where the plasma density outside of the <span class="hlt">flux</span> <span class="hlt">tube</span> is much greater, will be observed as an enhancement in the magnitude of the <span class="hlt">magnetic</span> field. Cassini magnetometer and CAPS data are examined to understand the properties of these <span class="hlt">flux</span> <span class="hlt">tubes</span> and their radial and latitudinal evolution throughout the Saturnian magnetospheric environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SoPh..292..110B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SoPh..292..110B"><span>Seismology of Oscillating <span class="hlt">Flux</span> <span class="hlt">Tube</span> with Twisted <span class="hlt">Magnetic</span> Field and Plasma Flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bahari, Karam</p> <p>2017-08-01</p> <p>Transverse oscillations of a thin coronal loop in a zero-beta plasma in the presence of a twisted <span class="hlt">magnetic</span> field and flow are investigated. The dispersion relation is obtained in the limit of weak twist. The twisted <span class="hlt">magnetic</span> field modifies the phase difference and asymmetry of standing kink oscillations caused by the flow. Using data from observations the kink speed and flow speed have been determined. The presence of the twisted <span class="hlt">magnetic</span> field can cause underestimation or overestimation of the flow speed in coronal loops depending on the direction of the flow and twisted <span class="hlt">magnetic</span> field, but a twisted <span class="hlt">magnetic</span> field has little effect on the estimated value of the kink speed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023629','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023629"><span><span class="hlt">Magnetic-flux</span> pump</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hildebrandt, A. F.; Elleman, D. D.; Whitmore, F. C. (Inventor)</p> <p>1966-01-01</p> <p>A <span class="hlt">magnetic</span> <span class="hlt">flux</span> pump is described for increasing the intensity of a <span class="hlt">magnetic</span> field by transferring <span class="hlt">flux</span> from one location to the <span class="hlt">magnetic</span> field. The device includes a pair of communicating cavities formed in a block of superconducting material, and a piston for displacing the trapped <span class="hlt">magnetic</span> <span class="hlt">flux</span> into the secondary cavity producing a field having an intense <span class="hlt">flux</span> density.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920059889&hterms=equilibrium+constants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dequilibrium%2Bconstants','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920059889&hterms=equilibrium+constants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dequilibrium%2Bconstants"><span>Resonant behaviour of MHD waves on <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. III - Effect of equilibrium flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goossens, Marcel; Hollweg, Joseph V.; Sakurai, Takashi</p> <p>1992-01-01</p> <p>The Hollweg et al. (1990) analysis of MHD surface waves in a stationary equilibrium is extended. The conservation laws and jump conditions at Alfven and slow resonance points obtained by Sakurai et al. (1990) are generalized to include an equilibrium flow, and the assumption that the Eulerian perturbation of total pressure is constant is recovered as the special case of the conservation law for an equilibrium with straight <span class="hlt">magnetic</span> field lines and flow along the <span class="hlt">magnetic</span> field lines. It is shown that the conclusions formulated by Hollweg et al. are still valid for the straight cylindrical case. The effect of curvature is examined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH13A2038I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH13A2038I"><span>Laboratory Experiment of <span class="hlt">Magnetic</span> Reconnection between Merging <span class="hlt">Flux</span> <span class="hlt">Tubes</span> with Strong Guide FIeld</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inomoto, M.; Kamio, S.; Kuwahata, A.; Ono, Y.</p> <p>2013-12-01</p> <p><span class="hlt">Magnetic</span> reconnection governs variety of energy release events in the universe, such as solar flares, geomagnetic substorms, and sawtooth crash in laboratory nuclear fusion experiments. Differently from the classical steady reconnection models, non-steady behavior of <span class="hlt">magnetic</span> reconnection is often observed. In solar flares, intermittent enhancement of HXR emission is observed synchronously with multiple ejection of plammoids [1]. In laboratory reconnection experiments, the existence of the guide field, that is perpendicular to the reconnection field, makes significant changes on reconnection process. Generally the guide field will slow down the reconnection rate due to the increased <span class="hlt">magnetic</span> pressure inside the current sheet. It also brings about asymmetric structure of the separatrices or effective particle acceleration in collisionless conditions. We have conducted laboratory experiments to study the behavior of the guide-field <span class="hlt">magnetic</span> reconnection using plasma merging technique (push reconnection). Under substantial guide field even larger than the reconnection field, the reconnection generally exhibits non-steady feature which involves intermittent detachment of X-point and reconnection current center[2]. Transient enhancement of reconnection rate is observed simultaneously with the X-point motion[3]. We found two distinct phenomena associated with the guide-field non-steady reconnection. The one is the temporal and localized He II emission from X-point region, suggesting the production of energetic electrons which could excite the He ions in the vicinity of the X-point. The other is the excitation of large-amplitude electromagnetic waves which have similar properties with kinetic Alfven waves, whose amplitude show positive correlation with the enhancement of the reconnection electric field[4]. Electron beam instability caused by the energetic electrons accelerated to more than twice of the electron thermal velocity could be a potential driver of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830012580&hterms=Readjustment+physical&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReadjustment%2Bphysical','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830012580&hterms=Readjustment+physical&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DReadjustment%2Bphysical"><span>Dynamic phenomena in coronal <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mariska, J. T.; Boris, J. P.</p> <p>1981-01-01</p> <p>The study of stellar atmospheres and the determination of specific physical mechanisms, geometries, and <span class="hlt">magnetic</span> structures by which coronae are maintained is examined. Ultraviolet and soft X-ray components observed in the radiative output of cool stars and the Sun require counterentropic temperature gradients for their explanation. The existence of a hot corona is recognized as a result of mechanical or fluid dynamic effects and the importance of the <span class="hlt">magnetic</span> field in the heating is accepted. Magnetohydrodynamic energy release associated with the emergence of <span class="hlt">magnetic</span> <span class="hlt">flux</span> through the chromosphere and its dynamic readjustment in the corona are major counterentropic phenomena which are considered as primary candidates for corona heating. Systematic plows in coronal <span class="hlt">flux</span> <span class="hlt">tubes</span> result from asymmetric heating and systematic flows can exist without substantial chromospheric pressure differences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21503884','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21503884"><span>Chromoelectric <span class="hlt">flux</span> <span class="hlt">tubes</span> in QCD</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cardaci, Mario Salvatore; Cea, Paolo; Cosmai, Leonardo; Falcone, Rossella; Papa, Alessandro</p> <p>2011-01-01</p> <p>We analyze the distribution of the chromoelectric field generated by a static quark-antiquark pair in the SU(3) vacuum and revisit previous results for SU(2). We find that the transverse profile of the <span class="hlt">flux</span> <span class="hlt">tube</span> resembles the dual version of the Abrikosov vortex field distribution. We give an estimate of the London penetration length of the chromoelectric field in the confined vacuum. We also speculate on the value of the ratio between the penetration lengths for SU(2) and SU(3) gauge theories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.1947S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.1947S"><span>Interaction of twisted curved <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Selwa, Malgorzata; Parnell, Clare; Priest, Eric</p> <p></p> <p>Most solar eruptions are initiated from sigmoidal structures. We perform 3D MHD numerical experiments of the interaction of force-free dipolar <span class="hlt">flux</span> <span class="hlt">tubes</span>. The <span class="hlt">magnetic</span> configuration is initialized as either a potential or a force-free dipole with a constant density. Next we perturb the dipoles by twisting or rotating them leading to reconnection in a resistive MHD regime. We compare the connectivity, energetics and topological features in both models, vary the contact angle of the dipoles and check if the initial configuration (sigmoidal or not) affects flares and eruption initiation leading to faster and stronger reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhPl...20i2511C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhPl...20i2511C"><span>Benchmarking gyrokinetic simulations in a toroidal <span class="hlt">flux-tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Y.; Parker, S. E.; Wan, W.; Bravenec, R.</p> <p>2013-09-01</p> <p>A <span class="hlt">flux-tube</span> model is implemented in the global turbulence code GEM [Y. Chen and S. E. Parker, J. Comput. Phys. 220, 839 (2007)] in order to facilitate benchmarking with Eulerian codes. The global GEM assumes the <span class="hlt">magnetic</span> equilibrium to be completely given. The initial <span class="hlt">flux-tube</span> implementation simply selects a radial location as the center of the <span class="hlt">flux-tube</span> and a radial size of the <span class="hlt">flux-tube</span>, sets all equilibrium quantities (B, ∇B, etc.) to be equal to the values at the center of the <span class="hlt">flux-tube</span>, and retains only a linear radial profile of the safety factor needed for boundary conditions. This implementation shows disagreement with Eulerian codes in linear simulations. An alternative <span class="hlt">flux-tube</span> model based on a complete local equilibrium solution of the Grad-Shafranov equation [J. Candy, Plasma Phys. Controlled Fusion 51, 105009 (2009)] is then implemented. This results in better agreement between Eulerian codes and the particle-in-cell (PIC) method. The PIC algorithm based on the v||-formalism [J. Reynders, Ph.D. dissertation, Princeton University, 1992] and the gyrokinetic ion/fluid electron hybrid model with kinetic electron closure [Y. Chan and S. E. Parker, Phys. Plasmas 18, 055703 (2011)] are also implemented in the <span class="hlt">flux-tube</span> geometry and compared with the direct method for both the ion temperature gradient driven modes and the kinetic ballooning modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22220612','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22220612"><span>Benchmarking gyrokinetic simulations in a toroidal <span class="hlt">flux-tube</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chen, Y.; Parker, S. E.; Wan, W.; Bravenec, R.</p> <p>2013-09-15</p> <p>A <span class="hlt">flux-tube</span> model is implemented in the global turbulence code GEM [Y. Chen and S. E. Parker, J. Comput. Phys. 220, 839 (2007)] in order to facilitate benchmarking with Eulerian codes. The global GEM assumes the <span class="hlt">magnetic</span> equilibrium to be completely given. The initial <span class="hlt">flux-tube</span> implementation simply selects a radial location as the center of the <span class="hlt">flux-tube</span> and a radial size of the <span class="hlt">flux-tube</span>, sets all equilibrium quantities (B, ∇B, etc.) to be equal to the values at the center of the <span class="hlt">flux-tube</span>, and retains only a linear radial profile of the safety factor needed for boundary conditions. This implementation shows disagreement with Eulerian codes in linear simulations. An alternative <span class="hlt">flux-tube</span> model based on a complete local equilibrium solution of the Grad-Shafranov equation [J. Candy, Plasma Phys. Controlled Fusion 51, 105009 (2009)] is then implemented. This results in better agreement between Eulerian codes and the particle-in-cell (PIC) method. The PIC algorithm based on the v{sub ||}-formalism [J. Reynders, Ph.D. dissertation, Princeton University, 1992] and the gyrokinetic ion/fluid electron hybrid model with kinetic electron closure [Y. Chan and S. E. Parker, Phys. Plasmas 18, 055703 (2011)] are also implemented in the <span class="hlt">flux-tube</span> geometry and compared with the direct method for both the ion temperature gradient driven modes and the kinetic ballooning modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22167597','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22167597"><span>OBSERVATION OF <span class="hlt">FLUX-TUBE</span> CROSSINGS IN THE SOLAR WIND</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arnold, L.; Li, G.; Li, X.; Yan, Y.</p> <p>2013-03-20</p> <p>Current sheets are ubiquitous in the solar wind. They are a major source of the solar wind MHD turbulence intermittency. They may result from nonlinear interactions of the solar wind MHD turbulence or are the boundaries of <span class="hlt">flux</span> <span class="hlt">tubes</span> that originate from the solar surface. Some current sheets appear in pairs and are the boundaries of transient structures such as <span class="hlt">magnetic</span> holes and reconnection exhausts or the edges of pulsed Alfven waves. For an individual current sheet, discerning whether it is a <span class="hlt">flux-tube</span> boundary or due to nonlinear interactions or the boundary of a transient structure is difficult. In this work, using data from the Wind spacecraft, we identify two three-current-sheet events. Detailed examination of these two events suggests that they are best explained by the <span class="hlt">flux-tube</span>-crossing scenario. Our study provides convincing evidence supporting the scenario that the solar wind consists of <span class="hlt">flux</span> <span class="hlt">tubes</span> where distinct plasmas reside.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4750201R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4750201R"><span>Transport of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in Saturn’s inner magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russell, Christopher T.; Lai, H. R.; Wei, H. Y.; Jia, Y. D.; Dougherty, M. K.</p> <p>2015-11-01</p> <p>The dynamics of the Saturnian magnetosphere, which rotates rapidly with an internal plasma source provided by Enceladus, qualitatively resembles those of the jovian magnetosphere powered by Io. The newly added plasma is accelerated to the corotation speed and moves outward together with the <span class="hlt">magnetic</span> <span class="hlt">flux</span>. In the near tail region, reconnection cuts the <span class="hlt">magnetic</span> <span class="hlt">flux</span>, reconnects it into plasma-depleted inward moving <span class="hlt">flux</span> <span class="hlt">tubes</span> and outward moving massive plasmoids. The buoyant empty <span class="hlt">tubes</span> then convect inward against the outward flow to conserve the total <span class="hlt">magnetic</span> <span class="hlt">flux</span> established by the internal dynamo. In both jovian and saturnian magnetospheres, <span class="hlt">flux</span> <span class="hlt">tubes</span> with enhanced field strength relative to their surroundings are detected in the equatorial region. Recent observations show that there are <span class="hlt">flux</span> <span class="hlt">tubes</span> with reduced field strength off the equator in the saturnian magnetosphere. To understand the formation mechanism of both types of <span class="hlt">flux</span> <span class="hlt">tubes</span>, we have surveyed all the available 1-sec <span class="hlt">magnetic</span> field data from Cassini. The systematic statistical study confirms the different latitudinal distributions of the two types of <span class="hlt">flux</span> <span class="hlt">tubes</span>. In addition, enhanced-field <span class="hlt">flux</span> <span class="hlt">tubes</span> are closer to the planet while reduced-field <span class="hlt">flux</span> <span class="hlt">tubes</span> can be detected at larger distances; both types of <span class="hlt">flux</span> <span class="hlt">tubes</span> become indistinguishable from the background <span class="hlt">magnetic</span> <span class="hlt">flux</span> inside an L-value of about 4; the local time distribution of both types of <span class="hlt">flux</span> <span class="hlt">tubes</span> are similar and they contain about the same amount of <span class="hlt">magnetic</span> <span class="hlt">flux</span>. Therefore, the two types of <span class="hlt">flux</span> <span class="hlt">tubes</span> are the same phenomena with different manifestations in different plasma environments. When the surrounding plasma density is high (near the equator and closer to the plasma source region), the <span class="hlt">flux</span> <span class="hlt">tubes</span> are compressed and have enhanced field strength inside; while in the low-plasma density region (off the equator and further from the plasma source region), the <span class="hlt">flux</span> <span class="hlt">tubes</span> expand and have reduced field strength inside.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH53B2488G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH53B2488G"><span>Dissipationless Damping of Compressive MHD Modes in Twisted <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giagkiozis, I.; Fedun, V.; Verth, G.; Goossens, M. L.; Van Doorsselaere, T.</p> <p>2015-12-01</p> <p>Axisymmetric modes in straight magentic <span class="hlt">flux</span> <span class="hlt">tubes</span> exhibit a cutoff in the long wavelength limit and no damping is predicted. However, as soon as weak <span class="hlt">magnetic</span> twist is introduced inside as well as outside the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> the cutoff recedes. Furthermore, when density variations are also incomporated within the modelresonant absorption appears. In this work we explore analytically the expected damping times for waves within the Alfven continuum for different solar atmospheric conditions. Based on the results in this work we offer insight on recent observations of sausage wave damping in the chromosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/413376','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/413376"><span>Monte Carlo simulation of false alarms and detection reliability in <span class="hlt">magnetic</span> <span class="hlt">flux</span> leakage inspection of steel <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Altschuler, E.; Pignotti, A.; Paiuk, J.</p> <p>1996-09-01</p> <p>The same flaw gives rise to different signals when inspected by the same nondestructive testing (NDT) equipment under closely similar circumstances. A laboratory example involving six identical cracks is shown. This is a consequence of unavoidable fluctuations in the parameters that influence the detection process and is illustrated using a Monte Carlo simulation based on a numerical model of crack detection in steel pipes by <span class="hlt">magnetic</span> <span class="hlt">flux</span> leakage. The effects of these uncertainties on the fault detection reliability and on the appearance of false alarms are analyzed. The occurrence of Type I errors (lack of detection of unacceptable defects) and Type II errors (false alarms) is studied as a function of the detection threshold, and guidelines for improving detection efficiency are suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJMPA..3143001B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJMPA..3143001B"><span>Effective string description of confining <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandt, Bastian B.; Meineri, Marco</p> <p>2016-08-01</p> <p>We review the current knowledge about the theoretical foundations of the effective string theory for confining <span class="hlt">flux</span> <span class="hlt">tubes</span> and the comparison of the predictions to pure gauge lattice data. A concise presentation of the effective string theory is provided, incorporating recent developments. We summarize the predictions for the spectrum and the profile/width of the <span class="hlt">flux</span> <span class="hlt">tube</span> and their comparison to lattice data. The review closes with a short summary of open questions for future research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRA..118.3791S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRA..118.3791S"><span><span class="hlt">Flux</span> <span class="hlt">tube</span> analysis of L-band ionospheric scintillation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shume, E. B.; Mannucci, A. J.; Butala, M. D.; Pi, X.; Valladares, C. E.</p> <p>2013-06-01</p> <p>This manuscript presents <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> analysis of L-band signal scintillation in the nighttime equatorial and low-latitude ionosphere. Residues of the scintillation index S4 estimated from the L-band signals received from Geostationary Earth Orbit (GEO) satellites are employed in the analysis. The S4 estimates have been shown to be associated with simultaneous GPS VTEC variations derived from JPL's GIPSY-GIM package. We have applied the wavelet decomposition technique simultaneously on the S4 time series in a <span class="hlt">flux</span> <span class="hlt">tube</span> over the equatorial and low-latitude regions. The technique decomposes the S4 signal to identify the dominant mode of variabilities and the temporal variations of scintillation-producing irregularities in the context of a <span class="hlt">flux</span> <span class="hlt">tube</span>. Statistically significant regions of the wavelet power spectra considered in our study have mainly shown that (a) dominant plasma irregularities associated with S4 variabilities in a <span class="hlt">flux</span> <span class="hlt">tube</span> have periods of about 4 to 15 minutes (horizontal irregularity scales of about 24 to 90 km). These periods match short period gravity waves, (b) scintillation-producing irregularities are anisotropic along the <span class="hlt">flux</span> <span class="hlt">tube</span> and in the east-west direction, and (c) the occurrences of scintillation-producing irregularities along the <span class="hlt">flux</span> <span class="hlt">tube</span> indicate that the entire <span class="hlt">flux</span> <span class="hlt">tube</span> became unstable. However, plasma instability occurrences were not simultaneous in most cases along the <span class="hlt">flux</span> <span class="hlt">tube</span>, there were time delays of various orders. Understanding the attributes of L-band scintillation-producing irregularities could be important for developing measures to mitigate L-band signal degradation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SoPh..290..727P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SoPh..290..727P"><span>Evidence of Twisted <span class="hlt">Flux-Tube</span> Emergence in Active Regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poisson, M.; Mandrini, C. H.; Démoulin, P.; López Fuentes, M.</p> <p>2015-03-01</p> <p>Elongated <span class="hlt">magnetic</span> polarities are observed during the emergence phase of bipolar active regions (ARs). These extended features, called <span class="hlt">magnetic</span> tongues, are interpreted as a consequence of the azimuthal component of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the toroidal <span class="hlt">flux-tubes</span> that form ARs. We develop a new systematic and user-independent method to identify AR tongues. Our method is based on determining and analyzing the evolution of the AR main polarity inversion line (PIL). The effect of the tongues is quantified by measuring the acute angle [ τ] between the orientation of the PIL and the direction orthogonal to the AR main bipolar axis. We apply a simple model to simulate the emergence of a bipolar AR. This model lets us interpret the effect of <span class="hlt">magnetic</span> tongues on parameters that characterize ARs ( e.g. the PIL inclination and the tilt angles, and their evolution). In this idealized kinematic emergence model, τ is a monotonically increasing function of the twist and has the same sign as the <span class="hlt">magnetic</span> helicity. We systematically apply our procedure to a set of bipolar ARs (41 ARs) that were observed emerging in line-of-sight magnetograms over eight years. For most of the cases studied, the tongues only have a small influence on the AR tilt angle since tongues have a much lower <span class="hlt">magnetic</span> <span class="hlt">flux</span> than the more concentrated main polarities. From the observed evolution of τ, corrected for the temporal evolution of the tilt angle and its final value when the AR is fully emerged, we estimate the average number of turns in the subphotospherically emerging <span class="hlt">flux</span>-rope. These values for the 41 observed ARs are below unity, except for one. This indicates that subphotospheric <span class="hlt">flux</span>-ropes typically have a low amount of twist, i.e. highly twisted <span class="hlt">flux-tubes</span> are rare. Our results demonstrate that the evolution of the PIL is a robust indicator of the presence of tongues and constrains the amount of twist in emerging <span class="hlt">flux-tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ASSP...19..505S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ASSP...19..505S"><span>Vector <span class="hlt">Magnetic</span> Field in Emerging <span class="hlt">Flux</span> Regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmieder, B.; Pariat, E.</p> <p></p> <p>A crucial phase in <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence is the rise of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> through the solar photosphere, which represents a severe transition between the very different environments of the solar interior and corona. Multi-wavelength observations with Flare Genesis, TRACE, SoHO, and more recently with the vector magnetographs at THEMIS and Hida (DST) led to the following conclusions. The fragmented <span class="hlt">magnetic</span> field in the emergence region - with dipped field lines or bald patches - is directly related with Ellerman bombs, arch filament systems, and overlying coronal loops. Measurements of vector <span class="hlt">magnetic</span> fields have given evidence that undulating "serpentine" fields are present while <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> cross the photosphere. See the sketch below, and for more detail see Pariat et al. (2004, 2007); Watanabe et al. (2008):</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020067654&hterms=role+image&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drole%2Bimage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020067654&hterms=role+image&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drole%2Bimage"><span>Empty <span class="hlt">Flux</span> <span class="hlt">Tubes</span> and Plasmasphere Refilling as Seen by IMAGE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adrian, M. L.; Gallagher, D. L.; Sandel, B. R.; Green, J. L.; Reinish, B.; Goldstein, J.; Huegrich, T.</p> <p>2002-01-01</p> <p>When a plasmaspheric <span class="hlt">flux</span> <span class="hlt">tube</span> is empty, what plasma is actually missing? When a <span class="hlt">flux</span> <span class="hlt">tube</span> refills, where does the plasma accumulate first? How long does it take to refill a <span class="hlt">flux</span> <span class="hlt">tube</span> to a level that is essentially saturated? Owing to the observational difficulties of measuring the distribution of plasmaspheric plasma along a <span class="hlt">flux</span> <span class="hlt">tube</span>, these questions have remained unanswered over many decades of study since discovery of the plasmasphere. They are important questions, because of the role that plasmaspheric plasma plays in collisional losses of higher energy populations, in modifying instabilities for wave-particle interactions, and in influencing the transport of energy through plasma waves. The Extreme Ultraviolet Imager and the Radio Plasma Imager on the IMAGE Mission are providing new, critical observations of the dynamic outer plasmasphere where convective erosion and refilling dominate. Latitudinal density profiles along a single L-shell from BPI confirm earlier indications of a mid-latitude transition between the altitude organized structure of the ionosphere and L-shell organized plasmasphere. Emptied <span class="hlt">flux</span> <span class="hlt">tubes</span> often mean empty only above about 1 Re in altitude or below plus or minus 40 degrees in <span class="hlt">magnetic</span> latitude. Refilling to nearly saturated levels is found to take much less than that previously found necessary to complete the process. The observations behind these conclusions and the new light brought to plasmaspheric refilling will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DPPUP8064Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DPPUP8064Y"><span>A Laboratory Astrophysical Jet to Study Canonical <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>You, Setthivoine; von der Linden, Jens; Vereen, Keon; Carroll, Evan; Kamikawa, Yu; Lavine, Eric Sander</p> <p>2013-10-01</p> <p>A new research program aims to simulate a <span class="hlt">magnetically</span> driven jet launched by an accretion disk in a laboratory experiment. The experiment replaces an accretion disk that would rotate at impractical speeds in the laboratory with three concentric annular electrodes, independently biased by two sets of pulsed power supplies to generate <span class="hlt">magnetized</span> plasma shear flows. With three electrodes, the radial electric field can be set up to approximate the rotation profile of an accretion disk. The primary diagnostics include arrays of <span class="hlt">magnetic</span> probes to measure 3D <span class="hlt">magnetic</span> fields and arrays of lines-of-sight to measure 3D ion flows from vector tomography of ion Doppler spectral lines. The symmetry of fast gas puff sources is fine-tuned with a fast ion gauge to remove any anchoring effects of discrete gas holes on the azimuthal rotation of the plasma jet. The aim is to understand how <span class="hlt">magnetically</span> driven astrophysical jets become long and collimated, how they become unstable or turbulent, and investigate the physics from a canonical <span class="hlt">flux</span> <span class="hlt">tube</span> point-of-view. A canonical <span class="hlt">flux</span> <span class="hlt">tube</span> is a fundamental <span class="hlt">tube</span> of <span class="hlt">magnetic</span> <span class="hlt">flux</span> with helical flows. This work is supported by the US DOE Grant DE-SC0010340</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140017439','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140017439"><span>High-Energy X-Ray Detection of G359.89-0.08 (SGR A-E): <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> Emission Powered by Cosmic Rays?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Tomsick, John A; Zhang, Will</p> <p>2014-01-01</p> <p>We report the first detection of high-energy X-ray (E (is) greater than 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to approximately 50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index gamma approximately equals 2.3 confirms a non-thermal emission mechanism. The observed <span class="hlt">flux</span> in the 3-79 keV band is F(sub X) = (2.0 +/- 0.1) × 10(exp -12)erg cm(-2) s(-1) , corresponding to an unabsorbed X-ray luminosity L(sub X) = (2.6+/-0.8)×10(exp 34) erg s(-1) assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to (is) approximately 100 kyr) with low surface brightness and radii up to (is) approximately 30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...784....6Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...784....6Z"><span>High-energy X-Ray Detection of G359.89-0.08 (Sgr A-E): <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> Emission Powered by Cosmic Rays?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Shuo; Hailey, Charles J.; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Christensen, Finn E.; Gotthelf, Eric V.; Harrison, Fiona A.; Mori, Kaya; Nynka, Melania; Stern, Daniel; Tomsick, John A.; Zhang, William W.</p> <p>2014-03-01</p> <p>We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89-0.08 (Sgr A-E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ~50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index Γ ≈ 2.3 confirms a non-thermal emission mechanism. The observed <span class="hlt">flux</span> in the 3-79 keV band is FX = (2.0 ± 0.1) × 10-12 erg cm-2 s-1, corresponding to an unabsorbed X-ray luminosity LX = (2.6 ± 0.8) × 1034 erg s-1 assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A-E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to ~100 kyr) with low surface brightness and radii up to ~30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NuPhB.913..551B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NuPhB.913..551B"><span>Supersymmetric quantum mechanics of the <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Belitsky, A. V.</p> <p>2016-12-01</p> <p>The Operator Product Expansion approach to scattering amplitudes in maximally supersymmetric gauge theory operates in terms of pentagon transitions for excitations propagating on a color <span class="hlt">flux</span> <span class="hlt">tube</span>. These obey a set of axioms which allow one to determine them to all orders in 't Hooft coupling and confront against explicit calculations. One of the simplifying features of the formalism is the factorizability of multiparticle transitions in terms of single-particle ones. In this paper we extend an earlier consideration of a sector populated by one kind of excitations to the case of a system with fermionic as well as bosonic degrees of freedom to address the origin of the factorization. While the purely bosonic case was analyzed within an integrable noncompact open-spin chain model, the current case is solved in the framework of a supersymmetric sl (2 | 1) <span class="hlt">magnet</span>. We find the eigenfunctions for the multiparticle system making use of the R-matrix approach. Constructing resulting pentagon transitions, we prove their factorized form. The discussion corresponds to leading order of perturbation theory.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH13B2439K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH13B2439K"><span>Reconnection Between Twisted <span class="hlt">Flux</span> <span class="hlt">Tubes</span> - Implications for Coronal Heating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knizhnik, K. J.; Antiochos, S. K.; DeVore, C. R.; Klimchuk, J. A.; Wyper, P. F.</p> <p>2015-12-01</p> <p>The nature of the heating of the Sun's corona has been a long-standing unanswered problem in solar physics. Beginning with the work of Parker (1972), many authors have argued that the corona is continuously heated through numerous small-scale reconnection events known as nanoflares. In these nanoflare models, stressing of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> by photospheric motions causes the field to become misaligned, producing current sheets in the corona. These current sheets then reconnect, converting the free energy stored in the <span class="hlt">magnetic</span> field into heat. In this work, we use the Adaptively Refined MHD Solver (ARMS) to perform 3D MHD simulations that dynamically resolve regions of strong current to study the reconnection between twisted <span class="hlt">flux</span> <span class="hlt">tubes</span> in a plane-parallel Parker configuration. We investigate the energetics of the process, and show that the <span class="hlt">flux</span> <span class="hlt">tubes</span> accumulate stress gradually before undergoing impulsive reconnection. We study the motion of the individual field lines during reconnection, and demonstrate that the connectivity of the configuration becomes extremely complex, with multiple current sheets being formed, which could lead to enhanced heating. In addition, we show that there is considerable interaction between the twisted <span class="hlt">flux</span> <span class="hlt">tubes</span> and the surrounding untwisted field, which contributes further to the formation of current sheets. The implications for observations will be discussed. This work was funded by a NASA Earth and Space Science Fellowship, and by the NASA TR&T Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020016726','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020016726"><span><span class="hlt">Flux</span> Compression <span class="hlt">Magnetic</span> Nozzle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thio, Y. C. Francis; Schafer, Charles (Technical Monitor)</p> <p>2001-01-01</p> <p>In pulsed fusion propulsion schemes in which the fusion energy creates a radially expanding plasma, a <span class="hlt">magnetic</span> nozzle is required to redirect the radially diverging flow of the expanding fusion plasma into a rearward axial flow, thereby producing a forward axial impulse to the vehicle. In a highly electrically conducting plasma, the presence of a <span class="hlt">magnetic</span> field B in the plasma creates a pressure B(exp 2)/2(mu) in the plasma, the <span class="hlt">magnetic</span> pressure. A gradient in the <span class="hlt">magnetic</span> pressure can be used to decelerate the plasma traveling in the direction of increasing <span class="hlt">magnetic</span> field, or to accelerate a plasma from rest in the direction of decreasing <span class="hlt">magnetic</span> pressure. In principle, ignoring dissipative processes, it is possible to design <span class="hlt">magnetic</span> configurations to produce an 'elastic' deflection of a plasma beam. In particular, it is conceivable that, by an appropriate arrangement of a set of coils, a good approximation to a parabolic '<span class="hlt">magnetic</span> mirror' may be formed, such that a beam of charged particles emanating from the focal point of the parabolic mirror would be reflected by the mirror to travel axially away from the mirror. The degree to which this may be accomplished depends on the degree of control one has over the <span class="hlt">flux</span> surface of the <span class="hlt">magnetic</span> field, which changes as a result of its interaction with a moving plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ASPC..416..489F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ASPC..416..489F"><span>Modeling the Subsurface Evolution of Active-Region <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, Y.</p> <p>2009-12-01</p> <p>I present results from a set of 3-D spherical-shell MHD simulations of the buoyant rise of active region <span class="hlt">flux</span> <span class="hlt">tubes</span> in the solar interior that put new constraints on the initial twist of the subsurface <span class="hlt">tubes</span> in order for them to emerge with tilt angles consistent with the observed Joy's law for the mean tilt of solar active regions. Due to asymmetric stretching of the Ω-shaped <span class="hlt">tube</span> by the Coriolis force, a field strength asymmetry develops with the leading side having a greater field strength and thus being more cohesive compared to the following side. Furthermore, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the leading leg shows more coherent values of local twist α ≡ <STRONG>J</STRONG> ṡ <STRONG>B</STRONG> / B2, whereas the values in the following leg show large fluctuations and are of mixed signs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21319525','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21319525"><span>CURRENT BUILDUP IN EMERGING SERPENTINE <span class="hlt">FLUX</span> <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pariat, E.; Masson, S.; Aulanier, G.</p> <p>2009-08-20</p> <p>The increase of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the solar atmosphere during active-region formation involves the transport of the <span class="hlt">magnetic</span> field from the solar convection zone through the lowest layers of the solar atmosphere, through which the plasma {beta} changes from >1 to <1 with altitude. The crossing of this <span class="hlt">magnetic</span> transition zone requires the <span class="hlt">magnetic</span> field to adopt a serpentine shape also known as the sea-serpent topology. In the frame of the resistive <span class="hlt">flux</span>-emergence model, the rising of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> is believed to be dynamically driven by a succession of <span class="hlt">magnetic</span> reconnections which are commonly observed in emerging <span class="hlt">flux</span> regions as Ellerman bombs. Using a data-driven, three-dimensional (3D) magnetohydrodynamic numerical simulation of <span class="hlt">flux</span> emergence occurring in active region 10191 on 2002 November 16-17, we study the development of 3D electric current sheets. We show that these currents buildup along the 3D serpentine <span class="hlt">magnetic</span>-field structure as a result of photospheric diverging horizontal line-tied motions that emulate the observed photospheric evolution. We observe that reconnection can not only develop following a pinching evolution of the serpentine field line, as usually assumed in two-dimensional geometry, but can also result from 3D shearing deformation of the <span class="hlt">magnetic</span> structure. In addition, we report for the first time on the observation in the UV domain with the Transition Region and Coronal Explorer (TRACE) of extremely transient loop-like features, appearing within the emerging <span class="hlt">flux</span> domain, which link several Ellermam bombs with one another. We argue that these loop transients can be explained as a consequence of the currents that build up along the serpentine <span class="hlt">magnetic</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E1045G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E1045G"><span>Doppler displacements in kink MHD waves in solar <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goossens, Marcel; Van Doorsselaere, Tom; Terradas, Jaume; Verth, Gary; Soler, Roberto</p> <p></p> <p>Doppler displacements in kink MHD waves in solar <span class="hlt">flux</span> <span class="hlt">tubes</span> Presenting author: M. Goossens Co-authors: R. Soler, J. Terradas, T. Van Doorsselaere, G. Verth The standard interpretation of the transverse MHD waves observed in the solar atmosphere is that they are non-axisymmetric kink m=1) waves on <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. This interpretation is based on the fact that axisymmetric and non-axisymmetric fluting waves do not displace the axis of the loop and the loop as a whole while kink waves indeed do so. A uniform transverse motion produces a Doppler displacement that is constant across the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span>. A recent development is the observation of Doppler displacements that vary across the loop. The aim of the present contribution is to show that spatial variations of the Doppler displacements across the loop can be caused by kink waves. The motion associated with a kink wave is purely transverse only when the <span class="hlt">flux</span> <span class="hlt">tube</span> is uniform and sufficiently thin. Only in that case do the radial and azimuthal components of displacement have the same amplitude and is the azimuthal component a quarter of a period ahead of the radial component. This results in a unidirectional or transverse displacement. When the <span class="hlt">flux</span> <span class="hlt">tube</span> is non-uniform and has a non-zero radius the conditions for the generation of a purely transverse motion are not any longer met. In that case the motion in a kink wave is the sum of a transverse motion and a non-axisymmetric rotational motion that depends on the azimuthal angle. It can produce complicated variations of the Doppler displacement across the loop. I shall discuss the various cases of possible Doppler displacenents that can occur depending on the relative sizes of the amplitudes of the radial and azimuthal components of the displacement in the kink wave and on the orientation of the line of sight.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21296471','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21296471"><span>Pair creation in an electric <span class="hlt">flux</span> <span class="hlt">tube</span> and chiral anomaly</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Iwazaki, Aiichi</p> <p>2009-11-15</p> <p>Using the chiral anomaly, we discuss the pair creation of massless fermions under the effect of a <span class="hlt">magnetic</span> field B-vector when an electric <span class="hlt">flux</span> <span class="hlt">tube</span> E-vector parallel to B-vector is switched on. The <span class="hlt">tube</span> is axially symmetric and infinitely long. For the constraint B>>E, we can analytically obtain the spatial and temporal behaviors of the number density of the fermions, the azimuthal <span class="hlt">magnetic</span> field generated by the fermions, and so on. We find that the lifetime t{sub c} of the electric field becomes shorter as the width of the <span class="hlt">tube</span> becomes narrower. Applying it to the plasma in high-energy heavy-ion collisions, we find that the color electric field decays quickly such that t{sub c}{approx_equal}Q{sub s}{sup -1}, in which Q{sub s} is the saturation momentum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22270961','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22270961"><span>NUMERICAL SIMULATIONS OF MULTIPLE SCATTERING OF THE f-MODE BY <span class="hlt">FLUX</span> <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Felipe, T.; Crouch, A.; Birch, A.</p> <p>2013-09-20</p> <p>We use numerical simulations to study the absorption and phase shift of surface-gravity waves caused by groups of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. The dependence of the scattering coefficients on the distance between the <span class="hlt">tubes</span> and their positions is analyzed for several cases with two or three <span class="hlt">flux</span> <span class="hlt">tubes</span> embedded in a quiet Sun atmosphere. The results are compared with those obtained neglecting completely or partially multiple scattering effects. We show that multiple scattering has a significant impact on the absorption measurements and tends to reduce the phase shift. We also consider more general cases of ensembles of randomly distributed <span class="hlt">flux</span> <span class="hlt">tubes</span>, and we have evaluated the effects on the scattering measurements of changing the number of <span class="hlt">tubes</span> included in the bundle and the average distance between <span class="hlt">flux</span> <span class="hlt">tubes</span>. We find that for the longest wavelength incoming waves, multiple scattering enhances the absorption, and its efficiency increases with the number of <span class="hlt">flux</span> <span class="hlt">tubes</span> and the reduction of the distance between them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22351541','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22351541"><span>High-energy X-ray detection of G359.89–0.08 (SGR A–E): <span class="hlt">Magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> emission powered by cosmic rays?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Shuo; Hailey, Charles J.; Gotthelf, Eric V.; Mori, Kaya; Nynka, Melania; Baganoff, Frederick K.; Bauer, Franz E.; Boggs, Steven E.; Craig, William W.; Tomsick, John A.; Christensen, Finn E.; Harrison, Fiona A.; Stern, Daniel; Zhang, William W.</p> <p>2014-03-20</p> <p>We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89–0.08 (Sgr A–E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ∼50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index Γ ≈ 2.3 confirms a non-thermal emission mechanism. The observed <span class="hlt">flux</span> in the 3-79 keV band is F{sub X} = (2.0 ± 0.1) × 10{sup –12} erg cm{sup –2} s{sup –1}, corresponding to an unabsorbed X-ray luminosity L{sub X} = (2.6 ± 0.8) × 10{sup 34} erg s{sup –1} assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A–E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to ∼100 kyr) with low surface brightness and radii up to ∼30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040012679&hterms=turns&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D60%26Ntt%3Dturns','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040012679&hterms=turns&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D60%26Ntt%3Dturns"><span>Eruption of a Multiple-Turn Helical <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> in a Large Flare: Evidence for External and Internal Reconnection that Fits the Breakout Model of Solar <span class="hlt">Magnetic</span> Eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gary, G. Allen; Moore, R. L.</p> <p>2003-01-01</p> <p>We present observations and an interpretation of a unique multiple-turn spiral <span class="hlt">flux</span> <span class="hlt">tube</span> eruption from AR10030 on 2002 July 15. The TRACE CIV observations clearly show a <span class="hlt">flux</span> <span class="hlt">tube</span> that is helical and that is erupting from within a sheared <span class="hlt">magnetic</span> field. These observations are interpreted in the context of the breakout model for <span class="hlt">magnetic</span> field explosions. The initiation of the helix eruption starts 25 seconds after the peak of the flare s strongest impulsive spike of microwave gryosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double CME. The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection heats the two-ribbon flare and might or might not produce the helix. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong <span class="hlt">magnetic</span> shear in the region is associated with rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field <span class="hlt">magnetic</span> inversion line within a filament channel, and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation. However, the observations are compatible with internal reconnection in a sheared <span class="hlt">magnetic</span> arcade in the formation and eruption of the helix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040012679&hterms=Double+helix&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDouble%2Bhelix','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040012679&hterms=Double+helix&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDouble%2Bhelix"><span>Eruption of a Multiple-Turn Helical <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> in a Large Flare: Evidence for External and Internal Reconnection that Fits the Breakout Model of Solar <span class="hlt">Magnetic</span> Eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gary, G. Allen; Moore, R. L.</p> <p>2003-01-01</p> <p>We present observations and an interpretation of a unique multiple-turn spiral <span class="hlt">flux</span> <span class="hlt">tube</span> eruption from AR10030 on 2002 July 15. The TRACE CIV observations clearly show a <span class="hlt">flux</span> <span class="hlt">tube</span> that is helical and that is erupting from within a sheared <span class="hlt">magnetic</span> field. These observations are interpreted in the context of the breakout model for <span class="hlt">magnetic</span> field explosions. The initiation of the helix eruption starts 25 seconds after the peak of the flare s strongest impulsive spike of microwave gryosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double CME. The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection heats the two-ribbon flare and might or might not produce the helix. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong <span class="hlt">magnetic</span> shear in the region is associated with rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field <span class="hlt">magnetic</span> inversion line within a filament channel, and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation. However, the observations are compatible with internal reconnection in a sheared <span class="hlt">magnetic</span> arcade in the formation and eruption of the helix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21249717','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21249717"><span>Pentaquark in the <span class="hlt">flux</span> <span class="hlt">tube</span> model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Iwasaki, M.; Takagi, F.</p> <p>2008-03-01</p> <p>We propose a model for pentaquarks in an excited state in the <span class="hlt">flux</span> <span class="hlt">tube</span> picture. The pentaquark is assumed to be composed of two diquarks and an antiquark connected by a color <span class="hlt">flux</span> <span class="hlt">tube</span> with a junction. If the pentaquark is rotating rapidly, it is polarized into two clusters: one is a diquark and the other is an antiquark plus another diquark. Excited energy of this quasilinear system is calculated with the use of the WKB approximation. It is predicted that there exist quasistable excited pentaquarks: 1690 MeV(3/2{sup +}), 2000 MeV(5/2{sup -}), 2250 MeV(7/2{sup +}) etc., which decay mainly through three-body modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhRvD..77e4020I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhRvD..77e4020I"><span>Pentaquark in the <span class="hlt">flux</span> <span class="hlt">tube</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iwasaki, M.; Takagi, F.</p> <p>2008-03-01</p> <p>We propose a model for pentaquarks in an excited state in the <span class="hlt">flux</span> <span class="hlt">tube</span> picture. The pentaquark is assumed to be composed of two diquarks and an antiquark connected by a color <span class="hlt">flux</span> <span class="hlt">tube</span> with a junction. If the pentaquark is rotating rapidly, it is polarized into two clusters: one is a diquark and the other is an antiquark plus another diquark. Excited energy of this quasilinear system is calculated with the use of the WKB approximation. It is predicted that there exist quasistable excited pentaquarks: 1690MeV(3/2+), 2000MeV(5/2-), 2250MeV(7/2+) etc., which decay mainly through three-body modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910012511','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910012511"><span>Permanent <span class="hlt">magnet</span> <span class="hlt">flux</span>-biased <span class="hlt">magnetic</span> actuator with <span class="hlt">flux</span> feedback</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Groom, Nelson J. (Inventor)</p> <p>1991-01-01</p> <p>The invention is a permanent <span class="hlt">magnet</span> <span class="hlt">flux</span>-biased <span class="hlt">magnetic</span> actuator with <span class="hlt">flux</span> feedback for adjustably suspending an element on a single axis. The <span class="hlt">magnetic</span> actuator includes a pair of opposing electromagnets and provides bi-directional forces along the single axis to the suspended element. Permanent <span class="hlt">magnets</span> in <span class="hlt">flux</span> feedback loops from the opposing electromagnets establish a reference permanent <span class="hlt">magnet</span> <span class="hlt">flux</span>-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in the electromagnets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040121118&hterms=turns&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D50%26Ntt%3Dturns','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040121118&hterms=turns&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D50%26Ntt%3Dturns"><span>Eruption of a Multiple-Turn Helical <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> in a Large Flare: Evidence for External and Internal Reconnection that Fits the Breakout Model of Solar <span class="hlt">Magnetic</span> Eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gary, G. Allen; Moore, R. L.</p> <p>2004-01-01</p> <p>We present observations and an interpretation of a unique multiple-turn spiral <span class="hlt">flux</span> <span class="hlt">tube</span> eruption from active region 10030 on 2002 July 15. The TRACE C IV observations clearly show a <span class="hlt">flux</span> <span class="hlt">tube</span> that is helical and erupting from within a sheared <span class="hlt">magnetic</span> field. These observations are interpreted in the context of the breakout model for <span class="hlt">magnetic</span> field explosions. The initiation of the helix eruption. as determined by a linear backward extrapolation, starts 25 s after the peak of the flare's strongest impulsive spike of microwave gyrosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double coronal mass ejection (CME). The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection releases the helix and heats the two-ribbon flare. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong <span class="hlt">magnetic</span> shear in the region is compatible with the observed rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field <span class="hlt">magnetic</span> inversion line within a filament channel. and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040121118&hterms=Double+helix&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDouble%2Bhelix','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040121118&hterms=Double+helix&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDouble%2Bhelix"><span>Eruption of a Multiple-Turn Helical <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> <span class="hlt">Tube</span> in a Large Flare: Evidence for External and Internal Reconnection that Fits the Breakout Model of Solar <span class="hlt">Magnetic</span> Eruptions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gary, G. Allen; Moore, R. L.</p> <p>2004-01-01</p> <p>We present observations and an interpretation of a unique multiple-turn spiral <span class="hlt">flux</span> <span class="hlt">tube</span> eruption from active region 10030 on 2002 July 15. The TRACE C IV observations clearly show a <span class="hlt">flux</span> <span class="hlt">tube</span> that is helical and erupting from within a sheared <span class="hlt">magnetic</span> field. These observations are interpreted in the context of the breakout model for <span class="hlt">magnetic</span> field explosions. The initiation of the helix eruption. as determined by a linear backward extrapolation, starts 25 s after the peak of the flare's strongest impulsive spike of microwave gyrosynchrotron radiation early in the flare s explosive phase, implying that the sheared core field is not the site of the initial reconnection. Within the quadrupolar configuration of the active region, the external and internal reconnection sites are identified in each of two consecutive eruptive flares that produce a double coronal mass ejection (CME). The first external breakout reconnection apparently releases an underlying sheared core field and allows it to erupt, leading to internal reconnection in the wake of the erupting helix. This internal reconnection releases the helix and heats the two-ribbon flare. These events lead to the first CME and are followed by a second breakout that initiates a second and larger halo CME. The strong <span class="hlt">magnetic</span> shear in the region is compatible with the observed rapid proper motion and evolution of the active region. The multiple-turn helix originates from above a sheared-field <span class="hlt">magnetic</span> inversion line within a filament channel. and starts to erupt only after fast breakout reconnection has started. These observations are counter to the standard flare model and support the breakout model for eruptive flare initiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...838...89P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...838...89P"><span>A Multiple <span class="hlt">Flux-tube</span> Solar Wind Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinto, Rui F.; Rouillard, Alexis P.</p> <p>2017-04-01</p> <p>We present a new model, MULTI-VP, which computes the three-dimensional structure of the solar wind and includes the chromosphere, the transition region, and the corona and low heliosphere. MULTI-VP calculates a large ensemble of wind profiles flowing along open <span class="hlt">magnetic</span> field lines that sample the entire three-dimensional atmosphere or, alternatively, a given region of interest. The radial domain starts from the photosphere and typically extends to about 30 {R}ȯ . The elementary uni-dimensional wind solutions are based on a mature numerical scheme that was adapted in order to accept any <span class="hlt">flux-tube</span> geometry. We discuss here the first results obtained with this model. We use Potential Field Source-surface extrapolations of magnetograms from the Wilcox Solar Observatory to determine the structure of the background <span class="hlt">magnetic</span> field. Our results support the hypothesis that the geometry of the <span class="hlt">magnetic</span> <span class="hlt">flux-tubes</span> in the lower corona controls the distribution of slow and fast wind flows. The inverse correlation between density and speed far away from the Sun is a global effect resulting from small readjustments of the <span class="hlt">flux-tube</span> cross-sections in the high corona (necessary to achieve global pressure balance and a uniform open <span class="hlt">flux</span> distribution). In comparison to current global MHD models, MULTI-VP performs much faster and does not suffer from spurious cross-field diffusion effects. We show that MULTI-VP has the capability to predict correctly the dynamical and thermal properties of the background solar wind (wind speed, density, temperature, <span class="hlt">magnetic</span> field amplitude, and other derived quantities) and to approach real-time operation requirements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930057641&hterms=patten&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpatten','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930057641&hterms=patten&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpatten"><span>The dynamics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> rings</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Deluca, E. E.; Fisher, G. H.; Patten, B. M.</p> <p>1993-01-01</p> <p>The evolution of <span class="hlt">magnetic</span> fields in the presence of turbulent convection is examined using results of numerical simulations of closed <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> embedded in a steady 'ABC' flow field, which approximate some of the important characteristics of a turbulent convecting flow field. Three different evolutionary scenarios were found: expansion to a steady deformed ring; collapse to a compact fat <span class="hlt">flux</span> ring, separated from the expansion type of behavior by a critical length scale; and, occasionally, evolution toward an advecting, oscillatory state. The work suggests that small-scale flows will not have a strong effect on large-scale, strong fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvD..95k4511C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvD..95k4511C"><span><span class="hlt">Flux</span> <span class="hlt">tubes</span> in the QCD vacuum</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cea, Paolo; Cosmai, Leonardo; Cuteri, Francesca; Papa, Alessandro</p> <p>2017-06-01</p> <p>The hypothesis that the QCD vacuum can be modeled as a dual superconductor is a powerful tool to describe the distribution of the color field generated by a quark-antiquark static pair and, as such, can provide useful clues for the understanding of confinement. In this work we investigate, by lattice Monte Carlo simulations of the S U (3 ) pure gauge theory and of (2 +1 )-flavor QCD with physical mass settings, some properties of the chromoelectric <span class="hlt">flux</span> <span class="hlt">tube</span> at zero temperature and their dependence on the physical distance between the static sources. We draw some conclusions about the validity domain of the dual superconductor picture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864178','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864178"><span>Method for limiting heat <span class="hlt">flux</span> in double-wall <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Hwang, Jaw-Yeu</p> <p>1982-01-01</p> <p>A method of limiting the heat <span class="hlt">flux</span> in a portion of double-wall <span class="hlt">tubes</span> including heat treating the <span class="hlt">tubes</span> so that the walls separate when subjected to high heat <span class="hlt">flux</span> and supplying an inert gas mixture to the gap at the interface of the double-wall <span class="hlt">tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH14B..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH14B..03H"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> ropes at planetary magnetopauses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasegawa, H.</p> <p>2015-12-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> ropes at the magnetopause are generated as a result of magnetopause reconnection involving more than one X-line, and constitute a subgroup of <span class="hlt">flux</span> transfer events which are believed to result from transient, localized, and/or multiple X-line reconnection, i.e., time-dependent forms of magnetopause reconnection. Single X-line reconnection at the low-latitude magnetopause erodes the dayside closed field lines and contributes to <span class="hlt">magnetic</span> <span class="hlt">flux</span> transport into the magnetotail, which forms the basis for dynamic phenomena in the magnetosphere such as substorms and storms. On the other hand, multiple X-line reconnection can produce the field lines of various topologies and/or can cause complex interactions of reconnection jets or reconnected <span class="hlt">flux</span> <span class="hlt">tubes</span>, thus possibly reducing the efficiency of <span class="hlt">magnetic</span> energy transfer into the tail. This presentation discusses in situ observations at the terrestrial, Hermean, and Kronian magnetopauses and models for the generation, of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. In particular, we emphasize that <span class="hlt">magnetic</span> field (e.g., bipolar) signatures alone cannot be taken as evidence for the <span class="hlt">flux</span> ropes, and plasma signatures (Alfvenic ion jets, electron pitch-angle anisotropy, etc.) help identify their topological structure. We also present our recent studies using multi-spacecraft (Cluster or THEMIS) measurements at the terrestrial magnetopause for the reconstruction of their two-dimensional and three-dimensional structures based on the Grad-Shafranov and magneto-hydrostatic equations, respectively.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.3410L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.3410L"><span>The Return of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> to the Inner Saturnian Magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lai, Hairong; Russell, Christopher T.; Jia, Yingdong; Masters, Adam; Dougherty, Michele K.</p> <p>2017-04-01</p> <p>The addition of plasma to the rotating inner Saturnian magnetosphere drives the circulation of the <span class="hlt">magnetic</span> <span class="hlt">flux</span>. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> is loaded with cold plasma originating from Enceladus and its plasma torus. It then convects outward to the tail region, is emptied of plasma during reconnection events, and returns buoyantly to the inner magnetosphere. Returning <span class="hlt">flux</span> <span class="hlt">tubes</span> carry hot and tenuous plasma that serves as a marker of this type of <span class="hlt">flux</span> <span class="hlt">tube</span>. The plasma inside the <span class="hlt">tubes</span> drifts at different rates depending on energy in the curved and inhomogeneous magnetosphere when the <span class="hlt">tubes</span> convect inward. This energy dispersion can be used to track the <span class="hlt">flux</span> <span class="hlt">tube</span>. With data from MAG and CAPS, we model the energy dispersion of the electrons to determine the age and the point of return of the 'empty' <span class="hlt">flux</span> <span class="hlt">tubes</span>. The results show that even the 'fresh' <span class="hlt">flux</span> <span class="hlt">tubes</span> are several hours old when seen and they start to return at 19 Saturn radii, near Titan's orbit. This supports the hypothesis that returning <span class="hlt">flux</span> <span class="hlt">tubes</span> generated by reconnection in the far-tail region are injected directly into the inner magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015A%26A...574A.106A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...574A.106A"><span><span class="hlt">Magnetic</span> balltracking: Tracking the photospheric <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Attie, R.; Innes, D. E.</p> <p>2015-02-01</p> <p>Context. One aspect of understanding the dynamics of the quiet Sun is to quantify the evolution of the <span class="hlt">flux</span> within small-scale <span class="hlt">magnetic</span> features. These features are routinely observed in the quiet photosphere and were given various names, such as pores, knots, <span class="hlt">magnetic</span> patches. Aims: This work presents a new algorithm for tracking the evolution of the broad variety of small-scale <span class="hlt">magnetic</span> features in the photosphere, with a precision equal to the instrumental resolution. Methods: We have developed a new technique to track the evolution of the individual <span class="hlt">magnetic</span> features from magnetograms, called "<span class="hlt">magnetic</span> balltracking". It quantifies the <span class="hlt">flux</span> of the tracked features, and it can track the footpoints of <span class="hlt">magnetic</span> field lines inferred from <span class="hlt">magnetic</span> field extrapolation. The algorithm can detect and quantify <span class="hlt">flux</span> emergence, as well as <span class="hlt">flux</span> cancellation. Results: The capabilities of <span class="hlt">magnetic</span> balltracking are demonstrated with the detection and the tracking of two cases of <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence that lead to the brightening of X-ray loops. The maximum emerged <span class="hlt">flux</span> ranges from 1018 Mx to 1019 Mx (unsigned <span class="hlt">flux</span>) when the X-ray loops are observed. Movies associated to Figs. 6 and 18 are available in electronic form at http://www.aanda.org</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvD..96c4512C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvD..96c4512C"><span>Coulomb <span class="hlt">flux</span> <span class="hlt">tube</span> on the lattice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chung, Kristian; Greensite, Jeff</p> <p>2017-08-01</p> <p>In Coulomb gauge a longitudinal electric field is generated instantaneously with the creation of a static quark-antiquark pair. The field due to the quarks is a sum of two contributions, one from the quark and one from the antiquark, and there is no obvious reason that this sum should fall off exponentially with distance from the sources. We show here, however, from numerical simulations in pure SU(2) lattice gauge theory, that the color Coulomb electric field does in fact fall off exponentially with transverse distance away from a line joining static quark-antiquark sources, indicating the existence of a color Coulomb <span class="hlt">flux</span> <span class="hlt">tube</span>, and the absence of long-range Coulomb dipole fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920048659&hterms=3-dimensional&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D3-dimensional','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920048659&hterms=3-dimensional&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D3-dimensional"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> ropes in 3-dimensional MHD simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ogino, Tatsuki; Walker, Raymond J.; Ashour-Abdalla, Maha</p> <p>1990-01-01</p> <p>The interaction of the solar wind and the earth's magnetosphere is presently simulated by a 3D, time-dependent, global MHD method in order to model the magnetopause and magnetotail generation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. It is noted that strongly twisted and localized <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> simular to <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes appear at the subpolar magnetopause when the IMF has a large azimuthal component, as well as a southward component. Plasmoids are generated in the magnetotail after the formation of a near-earth <span class="hlt">magnetic</span> neutral line; the <span class="hlt">magnetic</span> field lines have a helical structure that is connected from dawn to dusk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920048659&hterms=ogino&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dogino','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920048659&hterms=ogino&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dogino"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> ropes in 3-dimensional MHD simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ogino, Tatsuki; Walker, Raymond J.; Ashour-Abdalla, Maha</p> <p>1990-01-01</p> <p>The interaction of the solar wind and the earth's magnetosphere is presently simulated by a 3D, time-dependent, global MHD method in order to model the magnetopause and magnetotail generation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. It is noted that strongly twisted and localized <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> simular to <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes appear at the subpolar magnetopause when the IMF has a large azimuthal component, as well as a southward component. Plasmoids are generated in the magnetotail after the formation of a near-earth <span class="hlt">magnetic</span> neutral line; the <span class="hlt">magnetic</span> field lines have a helical structure that is connected from dawn to dusk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GeoRL..36.8108D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeoRL..36.8108D"><span>Long-lived auroral structures and atmospheric losses through auroral <span class="hlt">flux</span> <span class="hlt">tubes</span> on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dubinin, E.; Fraenz, M.; Woch, J.; Barabash, S.; Lundin, R.</p> <p>2009-04-01</p> <p>The ASPERA-3 observations of electron and ion <span class="hlt">fluxes</span> over the regions dominated by crustal <span class="hlt">magnetic</span> fields show the existence of long-lived and active aurora-type <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> with a width of 20-150 km. The activity manifests itself by large electron energy <span class="hlt">fluxes</span> (≥10-4 W/m2) and strong distortions in the upper (350-400 km) ionosphere. In some events the peaked electron energy distributions typical for Earth aurora are so pronounced that they are present in velocity distribution functions. A significant depletion of such auroral <span class="hlt">flux</span> <span class="hlt">tubes</span> is accompanied by the appearance of oxygen beams and a heating of the ions of ionospheric origin. Auroral activity was observed on several subsequent orbits of the Mars Express spacecraft during more than two weeks implying a stable existence of aurora on Mars. Atmospheric loss driven by energy deposition in the auroral <span class="hlt">flux</span> <span class="hlt">tubes</span> is estimated as ˜1023 s-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPNP8078L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPNP8078L"><span>Investigating the Dynamics of Canonical <span class="hlt">Flux</span> <span class="hlt">Tubes</span> in Jet Geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lavine, Eric; You, Setthivoine</p> <p>2014-10-01</p> <p>Highly collimated plasma jets are frequently observed at galactic, stellar, and laboratory scales. Some models suppose these jets are magnetohydrodynamically-driven <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> filled with flowing plasma, but they do not agree on a collimation process. Some evidence supporting a universal MHD pumping mechanism has been obtained from planar electrode experiments with aspect ratios of ~10:1 however, these jets are subject to kink instabilities beyond a certain length and are unable to replicate the remarkable aspect ratios (10-1000:1) seen in astrophysical systems. Other models suppose these jets are flowing Z-pinch plasmas and experiments that use stabilizing shear flows have achieved aspect ratios of ~30:1, but are line tied at both ends. Can both collimation and stabilization mechanisms work together to produce long jets without kink instabilities and only one end tied to the central object? This question is evaluated from the point of view of canonical <span class="hlt">flux</span> <span class="hlt">tubes</span> and canonical helicity transport, indicating that jets can become long and collimated due to a combination of strong helical shear flows and conversion of <span class="hlt">magnetic</span> helicity into kinetic helicity. The MOCHI LabJet experiment is designed to study this in the laboratory. Supported by US DoE Early Career Grant DE-SC0010340.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996PhPl....3...10Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996PhPl....3...10Z"><span>Force-free thin <span class="hlt">flux</span> <span class="hlt">tubes</span>: Basic equations and stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhugzhda, Y. D.</p> <p>1996-01-01</p> <p>The thin <span class="hlt">flux</span> <span class="hlt">tube</span> approximation is considered for a straight, symmetrical, force-free, rigidly rotating <span class="hlt">flux</span> <span class="hlt">tube</span>. The derived set of equations describes <span class="hlt">tube</span>, body sausage, and Alfvén wave modes and is valid for any values of β. The linear waves and instabilities of force-free <span class="hlt">flux</span> <span class="hlt">tubes</span> are considered. The comparison of approximate and exact solutions for an untwisted, nonrotating <span class="hlt">flux</span> <span class="hlt">tube</span> is performed. It is shown that the approximate and exact dispersion equations coincides, except the 20% discrepancy of sausage frequencies. An effective cross section is proposed to introduce the removal of this discrepancy. It makes the derived approximation correct for the force-free thin <span class="hlt">flux</span> <span class="hlt">tube</span> dynamics, except the detailed structure of radial eigenfunction. The dispersion of Alfvén torsional waves in a force-free <span class="hlt">tubes</span> appears. The valve effect of one directional propagation of waves in rotating twisted <span class="hlt">tube</span> is revealed. The current and rotational sausage instabilities of a force-free, thin <span class="hlt">flux</span> <span class="hlt">tube</span> are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPD....4840301W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPD....4840301W"><span>Exploring the <span class="hlt">Flux</span> <span class="hlt">Tube</span> Paradigm in Solar-like Convection Zones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weber, Maria A.; Nelson, Nicholas; Browning, Matthew</p> <p>2017-08-01</p> <p>In the solar context, important insight into the <span class="hlt">flux</span> emergence process has been obtained by assuming the <span class="hlt">magnetism</span> giving rise to sunspots consists partly of idealized <span class="hlt">flux</span> <span class="hlt">tubes</span>. Global-scale dynamo models are only now beginning to capture some aspects of <span class="hlt">flux</span> emergence. In certain regimes, these simulations self-consistently generate <span class="hlt">magnetic</span> <span class="hlt">flux</span> structures that rise buoyantly through the computational domain. How similar are these dynamo-generated, rising <span class="hlt">flux</span> structures to traditional <span class="hlt">flux</span> <span class="hlt">tube</span> models? The work we present here is a step toward addressing this question. We utilize the thin <span class="hlt">flux</span> <span class="hlt">tube</span> (TFT) approximation to simply model the evolution of <span class="hlt">flux</span> <span class="hlt">tubes</span> in a global, three-dimensional geometry. The TFTs are embedded in convective flows taken from a global dynamo simulation of a rapidly rotating Sun within which buoyant <span class="hlt">flux</span> structures arise naturally from wreaths of <span class="hlt">magnetism</span>. The initial conditions of the TFTs are informed by rising <span class="hlt">flux</span> structures identified in the dynamo simulation. We compare the trajectories of the dynamo-generated <span class="hlt">flux</span> loops with those computed through the TFT approach. We also assess the nature of the relevant forces acting on both sets of <span class="hlt">flux</span> structures, such as buoyancy, the Coriolis force, and external forces imparted by the surrounding convection. To achieve the fast <15 day rise of the buoyant <span class="hlt">flux</span> structures, we must suppress the large retrograde flow established inside the TFTs which occurs due to a strong conservation of angular momentum as they move outward. This tendency is common in <span class="hlt">flux</span> <span class="hlt">tube</span> models in solar-like convection zones, but is not present to the same degree in the dynamo-generated <span class="hlt">flux</span> loops. We discuss the mechanisms that may be responsible for suppressing the axial flow inside the <span class="hlt">flux</span> <span class="hlt">tube</span>, and consider the implications this has regarding the role of the Coriolis force in explaining sunspot latitudes and the observed Joy’s Law trend of active regions. Our work aims to provide constraints, and possible</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070034737&hterms=industry+cluster&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dindustry%2Bcluster','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070034737&hterms=industry+cluster&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dindustry%2Bcluster"><span><span class="hlt">Flux</span> Transfer Events Simultaneously Observed by Polar and Cluster: <span class="hlt">Flux</span> Rope in the Subsolar Region and <span class="hlt">Flux</span> <span class="hlt">Tube</span> Addition to the Polar Cusp</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Le, G.; Zheng, Y.; Russell, C. T.; Pfaff, R. F.; Lin, N.; Slavin, J. A.; Parks, G.; Wilber, M.; Petrinec, S. M.; Lucek, E. A.; Reme, H.</p> <p>2007-01-01</p> <p>The phenomenon called <span class="hlt">flux</span> transfer events (FTEs) is widely accepted as the manifestation of time-dependent reconnection. In this paper, we present observational evidence of a <span class="hlt">flux</span> transfer event observed simultaneously at low-latitude by Polar and at high-latitude by Cluster. This event occurs on March 21, 2002, when both Cluster and Polar are located near local noon but with a large latitudinal separation. During the event, Cluster is moving outbound from the polar cusp to the magnetosheath, and Polar is in the magnetosheath near the equatorial magnetopause. The observations show that a <span class="hlt">flux</span> transfer event occurs between the equator and the northern cusp. Polar and Cluster observe the FTE s two open <span class="hlt">flux</span> <span class="hlt">tubes</span>: Polar encounters the southward moving <span class="hlt">flux</span> <span class="hlt">tube</span> near the equator; and Cluster the northward moving <span class="hlt">flux</span> <span class="hlt">tube</span> at high latitude. The low latitude FTE appears to be a <span class="hlt">flux</span> rope with helical <span class="hlt">magnetic</span> field lines as it has a strong core field and the <span class="hlt">magnetic</span> field component in the boundary normal direction exhibits a strong bi-polar variation. Unlike the low-latitude FTE, the high-latitude FTE observed by Cluster does not exhibit the characteristic bi-polar perturbation in the <span class="hlt">magnetic</span> field. But the plasma data clearly reveal its open <span class="hlt">flux</span> <span class="hlt">tube</span> configuration. It shows that the <span class="hlt">magnetic</span> field lines have straightened inside the FTE and become more aligned to the neighboring <span class="hlt">flux</span> <span class="hlt">tubes</span> as it moves to the cusp. Enhanced electrostatic fluctuations have been observed within the FTE core, both at low- and high-latitudes. This event provides a unique opportunity to understand high-latitude FTE signatures and the nature of time-varying reconnection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1352672','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1352672"><span>Triode for <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Quanta</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vlasko-Vlasov, V. K.; Colauto, F.; Benseman, T.; Rosenmann, D.; Kwok, W. -K.</p> <p>2016-11-15</p> <p>In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum <span class="hlt">magnetic</span> field carriers, where the flow of individual <span class="hlt">magnetic</span> vortices in a superconducting film is regulated by the <span class="hlt">magnetic</span> potential of striae of soft <span class="hlt">magnetic</span> strips deposited on the film surface. By rotating an applied in-plane field, the <span class="hlt">magnetic</span> strip potential can be varied due to changes in the <span class="hlt">magnetic</span> charges at the strip edges, allowing accelerated or retarded motion of <span class="hlt">magnetic</span> vortices inside the superconductor. Scaling down our design and reducing the gap width between the <span class="hlt">magnetic</span> stripes will enable controlled manipulation of individual vortices and creation of single <span class="hlt">flux</span> quantum circuitry for novel high-speed low-power superconducting electronics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1352672-triode-magnetic-flux-quanta','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1352672-triode-magnetic-flux-quanta"><span>Triode for <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Quanta</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Vlasko-Vlasov, V. K.; Colauto, F.; Benseman, T.; ...</p> <p>2016-11-15</p> <p>In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum <span class="hlt">magnetic</span> field carriers, where the flow of individual <span class="hlt">magnetic</span> vortices in a superconducting film is regulated by the <span class="hlt">magnetic</span> potential of striae of soft <span class="hlt">magnetic</span> strips deposited on the film surface. By rotating an applied in-plane field, the <span class="hlt">magnetic</span> strip potential can be varied due to changes in the <span class="hlt">magnetic</span> charges at the strip edges, allowing accelerated or retarded motion of <span class="hlt">magnetic</span> vortices inside the superconductor.more » Scaling down our design and reducing the gap width between the <span class="hlt">magnetic</span> stripes will enable controlled manipulation of individual vortices and creation of single <span class="hlt">flux</span> quantum circuitry for novel high-speed low-power superconducting electronics.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...636847V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...636847V"><span>Triode for <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Quanta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vlasko-Vlasov, V. K.; Colauto, F.; Benseman, T.; Rosenmann, D.; Kwok, W.-K.</p> <p>2016-11-01</p> <p>In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum <span class="hlt">magnetic</span> field carriers, where the flow of individual <span class="hlt">magnetic</span> vortices in a superconducting film is regulated by the <span class="hlt">magnetic</span> potential of striae of soft <span class="hlt">magnetic</span> strips deposited on the film surface. By rotating an applied in-plane field, the <span class="hlt">magnetic</span> strip potential can be varied due to changes in the <span class="hlt">magnetic</span> charges at the strip edges, allowing accelerated or retarded motion of <span class="hlt">magnetic</span> vortices inside the superconductor. Scaling down our design and reducing the gap width between the <span class="hlt">magnetic</span> stripes will enable controlled manipulation of individual vortices and creation of single <span class="hlt">flux</span> quantum circuitry for novel high-speed low-power superconducting electronics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27845375','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27845375"><span>Triode for <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Quanta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vlasko-Vlasov, V K; Colauto, F; Benseman, T; Rosenmann, D; Kwok, W-K</p> <p>2016-11-15</p> <p>In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum <span class="hlt">magnetic</span> field carriers, where the flow of individual <span class="hlt">magnetic</span> vortices in a superconducting film is regulated by the <span class="hlt">magnetic</span> potential of striae of soft <span class="hlt">magnetic</span> strips deposited on the film surface. By rotating an applied in-plane field, the <span class="hlt">magnetic</span> strip potential can be varied due to changes in the <span class="hlt">magnetic</span> charges at the strip edges, allowing accelerated or retarded motion of <span class="hlt">magnetic</span> vortices inside the superconductor. Scaling down our design and reducing the gap width between the <span class="hlt">magnetic</span> stripes will enable controlled manipulation of individual vortices and creation of single <span class="hlt">flux</span> quantum circuitry for novel high-speed low-power superconducting electronics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5378924','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5378924"><span>Triode for <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Quanta</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vlasko-Vlasov, V. K.; Colauto, F.; Benseman, T.; Rosenmann, D.; Kwok, W.-K.</p> <p>2016-01-01</p> <p>In an electronic triode, the electron current emanating from the cathode is regulated by the electric potential on a grid between the cathode and the anode. Here we demonstrate a triode for single quantum <span class="hlt">magnetic</span> field carriers, where the flow of individual <span class="hlt">magnetic</span> vortices in a superconducting film is regulated by the <span class="hlt">magnetic</span> potential of striae of soft <span class="hlt">magnetic</span> strips deposited on the film surface. By rotating an applied in-plane field, the <span class="hlt">magnetic</span> strip potential can be varied due to changes in the <span class="hlt">magnetic</span> charges at the strip edges, allowing accelerated or retarded motion of <span class="hlt">magnetic</span> vortices inside the superconductor. Scaling down our design and reducing the gap width between the <span class="hlt">magnetic</span> stripes will enable controlled manipulation of individual vortices and creation of single <span class="hlt">flux</span> quantum circuitry for novel high-speed low-power superconducting electronics. PMID:27845375</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvD..93e4012B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvD..93e4012B"><span>New constraint on effective field theories of the QCD <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, M.</p> <p>2016-03-01</p> <p>Effective <span class="hlt">magnetic</span> S U (N ) gauge theory with classical ZN <span class="hlt">flux</span> <span class="hlt">tubes</span> of intrinsic width 1/M is an effective field theory of the long-distance quark-antiquark interaction in S U (N ) Yang-Mills theory. Long-wavelength fluctuations of the ZN vortices of this theory lead to an effective string theory. In this paper, we clarify the connection between effective field theory and effective string theory, and we propose a new constraint on these vortices. We first examine the impact of string fluctuations on the classical dual superconductor description of confinement. At interquark distances R ˜1/M , the classical action for a straight <span class="hlt">flux</span> <span class="hlt">tube</span> determines the heavy quark potentials. At distances R ≫1/M , fluctuations of the <span class="hlt">flux</span> <span class="hlt">tube</span> axis x ˜ give rise to an effective string theory with an action Seff(x ˜), the classical action for a curved <span class="hlt">flux</span> <span class="hlt">tube</span>, evaluated in the limit 1/M →0 . This action is equal to the Nambu-Goto action. These conclusions are independent of the details of the ZN <span class="hlt">flux</span> <span class="hlt">tube</span>. Further, we assume the QCD <span class="hlt">flux</span> <span class="hlt">tube</span> satisfies the additional constraint, ∫0∞r d r T/θθ(r ) r2=0 , where T/θθ(r ) r2 is the value of the θ θ component of the stress tensor at a distance r from the axis of an infinite <span class="hlt">flux</span> <span class="hlt">tube</span>. Under this constraint, the string tension σ equals the force on a quark in the chromoelectric field E → of an infinite straight <span class="hlt">flux</span> <span class="hlt">tube</span>, and the Nambu-Goto action can be represented in terms of the chromodynamic fields of effective <span class="hlt">magnetic</span> S U (N ) gauge theory, yielding a field theory interpretation of effective string theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PrPNP..67..440B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PrPNP..67..440B"><span>Colour <span class="hlt">flux-tubes</span> in static pentaquark and tetraquark systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bicudo, Pedro; Cardoso, Nuno; Cardoso, Marco</p> <p>2012-04-01</p> <p>The colour fields created by the static tetraquark and pentaquark systems are computed in quenched SU(3) lattice QCD, with gauge invariant lattice operators, in a 243×48 lattice at β=6.2. We generate our quenched configurations with GPUs, and detail the respective benchmarks in different SU(N) groups. While at smaller distances the Coulomb potential is expected to dominate, at larger distances it is expected that fundamental <span class="hlt">flux</span> <span class="hlt">tubes</span>, similar to the <span class="hlt">flux-tube</span> between a quark and an antiquark, emerge and confine the quarks. In order to minimize the potential the fundamental <span class="hlt">flux</span> <span class="hlt">tubes</span> should connect at 120° angles. We compute the square of the colour fields utilizing plaquettes, and locate the static sources with generalized Wilson loops and with APE smearing. The tetraquark system is well described by a double-Y-shaped <span class="hlt">flux-tube</span>, with two Steiner points, but when quark-antiquark pairs are close enough the two junctions collapse and we have an X-shaped <span class="hlt">flux-tube</span>, with one Steiner point. The pentaquark system is well described by a three-Y-shaped <span class="hlt">flux-tube</span> where the three <span class="hlt">flux</span> junctions are Steiner points.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997PhLB..404..238L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997PhLB..404..238L"><span>J/ ψ-dissociation by a color electric <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loh, S.; Greiner, C.; Mosel, U.</p> <p>1997-02-01</p> <p>We address the question of how a c - c¯state (a J/ ψ) can be dissociated by the strong color electric fields when moving through a color electric <span class="hlt">flux</span> <span class="hlt">tube</span>. The color electric <span class="hlt">flux</span> <span class="hlt">tube</span> and the dissociation of the heavy quarkonia state are both described within the Friedberg-Lee color dielectric model. We speculate on the importance of such an effect with respect to the observed J/ ψ-suppression in ultrarelativistic heavy ion collisions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22047802','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22047802"><span>DYNAMICS OF <span class="hlt">MAGNETIZED</span> VORTEX <span class="hlt">TUBES</span> IN THE SOLAR CHROMOSPHERE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kitiashvili, I. N.; Kosovichev, A. G.; Mansour, N. N.; Wray, A. A.</p> <p>2012-05-20</p> <p>We use three-dimensional radiative MHD simulations to investigate the formation and dynamics of small-scale (less than 0.5 Mm in diameter) vortex <span class="hlt">tubes</span> spontaneously generated by turbulent convection in quiet-Sun regions with an initially weak (10 G) mean <span class="hlt">magnetic</span> field. The results show that the vortex <span class="hlt">tubes</span> penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere. The vortex <span class="hlt">tubes</span> are mostly concentrated in intergranular lanes and are characterized by strong (near sonic) downflows and swirling motions that capture and twist <span class="hlt">magnetic</span> field lines, forming <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> that expand with height and attain <span class="hlt">magnetic</span> field strengths ranging from 200 G in the chromosphere to more than 1 kG in the photosphere. We investigate in detail the physical properties of these vortex <span class="hlt">tubes</span>, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that <span class="hlt">magnetized</span> vortex <span class="hlt">tubes</span> provide an important path for energy and momentum transfer from the convection zone into the chromosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ApJ...629.1164L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ApJ...629.1164L"><span>A <span class="hlt">Flux</span> <span class="hlt">Tube</span> Solar Dynamo Model Based on the Competing Role of Buoyancy and Downflows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, L. H.; Sofia, S.; Belvedere, G.</p> <p>2005-08-01</p> <p>A <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> can be considered both as a separate body and as a confined field. As a field, it is affected by both differential rotation (Ω-effect) and cyclonic convection (α-effect). As a body, the <span class="hlt">tube</span> experiences not only a buoyant force, but also a dynamic pressure due to downflows above the <span class="hlt">tube</span>. These two competing dynamic effects are incorporated into the α-Ω dynamo equations through the total <span class="hlt">magnetic</span> turbulent diffusivity, leading to a <span class="hlt">flux</span> <span class="hlt">tube</span> dynamo operating in the convection zone. We analyze and solve the extended dynamo equations in the linear approximation by adopting the observed solar internal rotation and assuming a downflow effect derived from numerical simulations of a solar convection zone. The model reproduces the 22 yr cycle period; the extended butterfly diagram with the confinement of strong activity to low heliographic latitudes |Φ|<=35deg the evidence that at low latitudes the radial field is in an approximately π phase lag compared to the toroidal field at the same latitude; the evidence that the poleward branch is in a π/2 phase lag with respect to the equatorward branch; and the evidence that most of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> is present in an intermittent form, concentrated into strong <span class="hlt">flux</span> <span class="hlt">tubes</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPD....4811108L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPD....4811108L"><span>Studying the Formation and Evolution of Eruptive <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Linton, Mark</p> <p>2017-08-01</p> <p>Solar <span class="hlt">magnetic</span> eruptions are dramatic sources of solar activity, and dangerous sources of space weather hazards. Many of these eruptions take the form of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes, i.e., <span class="hlt">magnetic</span> fieldlines wrapping around a core <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span>. Investigating the processes which form these <span class="hlt">flux</span> ropes both prior to and during eruption, and investigating their evolution after eruption, can give us a critical window into understanding the sources of and processes involved in these eruptions. This presentation will discuss modeling and observational investigations into these various phases of <span class="hlt">flux</span> rope formation, eruption, and evolution, and will discuss how these different explorations can be used to develop a more complete picture of erupting <span class="hlt">flux</span> rope dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AASP....6...20B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AASP....6...20B"><span>Estimation of the <span class="hlt">flux</span> <span class="hlt">tube</span> diameters outside sunspots using Hinode observations. Preliminary results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Botygina, O. O.; Gordovskyy, M. Yu.; Lozitsky, V. G.</p> <p>2016-09-01</p> <p>Indirect estimations of diameters of the smallest <span class="hlt">flux</span> <span class="hlt">tubes</span> outside sunspots are made using SOT/Hinode observations of Fe I 6301.5 and 6302.5 lines. These estimations are based on the comparison of measured effective <span class="hlt">magnetic</span> field strength B_{eff} in named lines. It is shown that B_{eff}(6301.5)/B_{eff}(6302.5)≈ 1.3 in the range B_{eff}=40-300 G, and B_{eff} (6301.5)/B_{eff}(6302.5)≈.0 for B_{eff}≤10-20 G. The first case corresponds to the two-component <span class="hlt">magnetic</span> field with kG <span class="hlt">flux</span> <span class="hlt">tubes</span> and weak background field, whereas the second one corresponds to background field without <span class="hlt">flux</span> <span class="hlt">tubes</span>. Assuming that the field range B_{eff}=10-40 G corresponds to the case with only one <span class="hlt">flux</span> <span class="hlt">tube</span> in each pixel, the <span class="hlt">flux</span> <span class="hlt">tube</span> diameters should be 15-30 km. Possible influence of the brightness contrast and the Zeeman saturation could change this estimation by approximately 20%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM51E2549L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM51E2549L"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Circulation in the Saturnian Magnetosphere Revisited</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lai, H.; Russell, C. T.; Jia, Y. D.; Masters, A.; Dougherty, M. K.</p> <p>2016-12-01</p> <p>The <span class="hlt">magnetic</span> <span class="hlt">flux</span> circulation in the magnetosphere of Saturn is driven by the plasma sources in the inner magnetosphere. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> convects outward with the loaded cold plasma originated from Enceladus and the plasma torus, is emptied of plasma during tail reconnection events, and returns buoyantly to conserve the <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the inner magnetosphere. Returning <span class="hlt">magnetic</span> <span class="hlt">flux</span> can be recognized in <span class="hlt">magnetic</span> field data by the sharp changes in the field strength and in plasma data by the absence of cold plasma and appearance of hot particles. These hot particles are subject to gradient and curvature drift as they convect inward. This results in a dispersion of the hot particles that can be recognized in the energy-time spectrograms. Here we model the time evolution of the electron distribution. By comparing these models with Cassini observations, we can determine the age of the <span class="hlt">flux</span> <span class="hlt">tubes</span>, and can constrain the <span class="hlt">magnetic</span> <span class="hlt">flux</span> return. This greatly improves our quantitative understanding of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> circulation at Saturn. This same model can be applied to Jovian magnetosphere, which is also a fast rotator driven by internal mass-loading. We compare the inferred <span class="hlt">magnetic</span> <span class="hlt">flux</span> transport in the two systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM53A2208M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM53A2208M"><span>Spatial Transport of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Surfaces in Strongly Anisotropic Turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthaeus, W. H.; Servidio, S.; Wan, M.; Ruffolo, D. J.; Rappazzo, A. F.; Oughton, S.</p> <p>2013-12-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> surfaces afford familiar descriptions of spatial structure, dynamics, and connectivity of <span class="hlt">magnetic</span> fields, with particular relevance in contexts such as solar coronal <span class="hlt">flux</span> <span class="hlt">tubes</span>, <span class="hlt">magnetic</span> field connectivity in the interplanetary and interstellar medium, as well as in laboratory plasmas and dynamo problems [1-4]. Typical models assume that field-lines are orderly, and <span class="hlt">flux</span> <span class="hlt">tubes</span> remain identifiable over macroscopic distances; however, a previous study has shown that <span class="hlt">flux</span> <span class="hlt">tubes</span> shred in the presence of fluctuations, typically losing identity after several correlation scales [5]. Here, the structure of <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces is numerically investigated in a reduced magnetohydrodynamic (RMHD) model of homogeneous turbulence. Short and long-wavelength behavior is studied statistically by propagating <span class="hlt">magnetic</span> surfaces along the mean field. At small scales <span class="hlt">magnetic</span> surfaces become complex, experiencing an exponential thinning. At large scales, instead, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> undergoes a diffusive behavior. The link between the diffusion of the coarse-grained <span class="hlt">flux</span> and field-line random walk is established by means of a multiple scale analysis. Both large and small scales limits are controlled by the Kubo number. These results have consequences for understanding and interpreting processes such as <span class="hlt">magnetic</span> reconnection and field-line diffusion in plasmas [6]. [1] E. N. Parker, Cosmical <span class="hlt">Magnetic</span> Fields (Oxford Univ. Press, New York, 1979). [2] J. R. Jokipii and E. N. Parker, Phys. Rev. Lett. 21, 44 (1968). [3] R. Bruno et al., Planet. Space Sci. 49, 1201 (2001). [4] M. N. Rosenbluth et al., Nuclear Fusion 6, 297 (1966). [5] W. H. Matthaeus et al., Phys. Rev. Lett. 75, 2136 (1995). [6] S. Servidio et al., submitted (2013).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120016346','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120016346"><span>Force sensor using changes in <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pickens, Herman L. (Inventor); Richard, James A. (Inventor)</p> <p>2012-01-01</p> <p>A force sensor includes a magnetostrictive material and a <span class="hlt">magnetic</span> field generator positioned in proximity thereto. A <span class="hlt">magnetic</span> field is induced in and surrounding the magnetostrictive material such that lines of <span class="hlt">magnetic</span> <span class="hlt">flux</span> pass through the magnetostrictive material. A sensor positioned in the vicinity of the magnetostrictive material measures changes in one of <span class="hlt">flux</span> angle and <span class="hlt">flux</span> density when the magnetostrictive material experiences an applied force that is aligned with the lines of <span class="hlt">magnetic</span> <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NucFu..55a3015C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NucFu..55a3015C"><span>Dynamics of multiple <span class="hlt">flux</span> <span class="hlt">tubes</span> in sawtoothing KSTAR plasmas heated by electron cyclotron waves: I. Experimental analysis of the <span class="hlt">tube</span> structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choe, G. H.; Yun, G. S.; Nam, Y.; Lee, W.; Park, H. K.; Bierwage, A.; Domier, C. W.; Luhmann, N. C., Jr.; Jeong, J. H.; Bae, Y. S.; the KSTAR Team</p> <p>2015-01-01</p> <p>Multiple (two or more) <span class="hlt">flux</span> <span class="hlt">tubes</span> are commonly observed inside and/or near the q = 1 <span class="hlt">flux</span> surface in KSTAR tokamak plasmas with localized electron cyclotron resonance heating and current drive (ECH/CD). Detailed 2D and quasi-3D images of the <span class="hlt">flux</span> <span class="hlt">tubes</span> obtained by an advanced imaging diagnostic system showed that the <span class="hlt">flux</span> <span class="hlt">tubes</span> are m/n = 1/1 field-aligned structures co-rotating around the <span class="hlt">magnetic</span> axis. The <span class="hlt">flux</span> <span class="hlt">tubes</span> typically merge together and become like the internal kink mode of the usual sawtooth, which then collapses like a usual sawtooth crash. A systematic scan of ECH/CD beam position showed a strong correlation with the number of <span class="hlt">flux</span> <span class="hlt">tubes</span>. In the presence of multiple <span class="hlt">flux</span> <span class="hlt">tubes</span> close to the q = 1 surface, the radially outward heat transport was enhanced, which explains naturally temporal changes of electron temperature. We emphasize that the multiple <span class="hlt">flux</span> <span class="hlt">tubes</span> are a universal feature distinct from the internal kink instability and play a critical role in the control of sawteeth using ECH/CD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...592A..65P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...592A..65P"><span><span class="hlt">Flux-tube</span> geometry and solar wind speed during an activity cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinto, R. F.; Brun, A. S.; Rouillard, A. P.</p> <p>2016-07-01</p> <p>Context. The solar wind speed at 1 AU shows cyclic variations in latitude and in time which reflect the evolution of the global background <span class="hlt">magnetic</span> field during the activity cycle. It is commonly accepted that the terminal (asymptotic) wind speed in a given <span class="hlt">magnetic</span> <span class="hlt">flux-tube</span> is generally anti-correlated with its total expansion ratio, which motivated the definition of widely used semi-empirical scaling laws relating one to the other. In practice, such scaling laws require ad hoc corrections (especially for the slow wind in the vicinities of streamer/coronal hole boundaries) and empirical fits to in situ spacecraft data. A predictive law based solely on physical principles is still missing. Aims: We test whether the <span class="hlt">flux-tube</span> expansion is the controlling factor of the wind speed at all phases of the cycle and at all latitudes (close to and far from streamer boundaries) using a very large sample of wind-carrying open <span class="hlt">magnetic</span> <span class="hlt">flux-tubes</span>. We furthermore search for additional physical parameters based on the geometry of the coronal <span class="hlt">magnetic</span> field which have an influence on the terminal wind flow speed. Methods: We use numerical magneto-hydrodynamical simulations of the corona and wind coupled to a dynamo model to determine the properties of the coronal <span class="hlt">magnetic</span> field and of the wind velocity (as a function of time and latitude) during a whole 11-yr activity cycle. These simulations provide a large statistical ensemble of open <span class="hlt">flux-tubes</span> which we analyse conjointly in order to identify relations of dependence between the wind speed and geometrical parameters of the <span class="hlt">flux-tubes</span> which are valid globally (for all latitudes and moments of the cycle). Results: Our study confirms that the terminal (asymptotic) speed of the solar wind depends very strongly on the geometry of the open <span class="hlt">magnetic</span> <span class="hlt">flux-tubes</span> through which it flows. The total <span class="hlt">flux-tube</span> expansion is more clearly anti-correlated with the wind speed for fast rather than for slow wind flows, and effectively controls the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986STIN...8716243.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986STIN...8716243."><span>Boiling inside <span class="hlt">tubes</span>: Critical heat <span class="hlt">flux</span> for upward flow in uniformly heated vertical <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>1986-11-01</p> <p>ESDU 85041 recommended a procedure for estimating the heat <span class="hlt">flux</span> at different locations along a heated <span class="hlt">tube</span> through which a boiling liquid is flowing, assuming that the wall is wetted by the liquid. The purpose of this Data Item (ESDU 86032) is to enable the reader to check, in the case of flow up a uniformly heated vertical <span class="hlt">tube</span>, that the heat <span class="hlt">flux</span> does not exceed the critical value above which the liquid would not wet the wall. This point marks the onset of dryout accompanied by an increase in resistance to heat transfer and the possible onset of corrosion and overheating of the <span class="hlt">tube</span>. The open literature contains many experimental values of the critical heat <span class="hlt">flux</span> (CHF) in flow up electrically heated vertical <span class="hlt">tubes</span>, mostly with water or R.12. These results have been used to check various procedures for predicting CHF with flow up vertical <span class="hlt">tubes</span>. The recommended procedure is given in detail and illustrated in an example.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPD....4830005K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPD....4830005K"><span>The Emergence of Kinked <span class="hlt">Flux</span> <span class="hlt">Tubes</span> as the Source of Delta-Spots on the Photosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knizhnik, Kalman; Linton, Mark; Norton, Aimee Ann</p> <p>2017-08-01</p> <p>It has been observationally well established that the <span class="hlt">magnetic</span> configurations most favorable to producing energetic flaring events reside in so called delta-spots. These delta-spots are a subclass of sunspots, and are classified as sunspots which have umbrae (dark regions in the interior of sunspots) with opposite <span class="hlt">magnetic</span> polarities that share a common penumbra. They are characterized by strong rotation and an extremely compact <span class="hlt">magnetic</span> configuration, and are observed to follow an inverse-Hale law. It has been shown that over 90% of X-class flares that occurred during solar cycles 22 and 23 originated in delta-spots (Guo, Lin & Deng, 2014). Understanding the origin of delta-spots, therefore, is a crucial step towards the ultimate goal of space weather forecasting. In this work, we argue that delta-spots arise during the emergence of kinked <span class="hlt">flux</span> <span class="hlt">tubes</span> into the corona, and that their unique properties are due to the emergence of knots present in the kink mode of twisted <span class="hlt">flux</span> <span class="hlt">tubes</span>. We present numerical simulations that study the emergence of both kink-stable and unstable <span class="hlt">flux</span> <span class="hlt">tubes</span> into the solar corona, and demonstrate quantitatively that their photospheric signatures are dramatically different, with the latter <span class="hlt">flux</span> <span class="hlt">tubes</span> demonstrating strong coherent rotation and a very tight <span class="hlt">flux</span> distribution on the photosphere. We show that the coronal <span class="hlt">magnetic</span> field resulting from the emergence of a kinked <span class="hlt">flux</span> <span class="hlt">tube</span> contains significantly more free energy than the unkinked case, potentially leading to more energetic flares. We discuss the implications of our simulations for observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870039714&hterms=boltzmann+constant&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dboltzmann%2Bconstant','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870039714&hterms=boltzmann+constant&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dboltzmann%2Bconstant"><span>Temporal features of the refilling of a plasmaspheric <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Singh, Nagendra; Schunk, R. W.; Thiemann, H.</p> <p>1986-01-01</p> <p>The refilling of plasmaspheric <span class="hlt">flux</span> <span class="hlt">tubes</span> was studied by assuming that the protonosphere provides an ionospheric boundary where the H(+) density can be assumed; the supersonic flow in the <span class="hlt">flux</span> <span class="hlt">tube</span> is driven by the depletion of the plasma from the <span class="hlt">flux</span> <span class="hlt">tube</span>, while the base density and pressure in the protonosphere remain constant. The time-dependent continuity and momentum equations for the H(+) ions were solved. The electron gas was assumed to obey the Boltzmann law, and the proton gas was assumed to be isothermal. In agreement with the postulate of Banks et al. (1971), it was found that an important feature of the refilling is the formation of a shock pair at the equator; as the shocks propagate toward the ionosphere, the refilling occurs. Depending on the density at the ionospheric boundaries, a fair agreement was found between the refilling rates obtained for L = 6.6 and those from the GEOS 2 observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JETP..120..399D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JETP..120..399D"><span><span class="hlt">Flux</span> <span class="hlt">tube</span> spectra from approximate integrability at low energies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dubovsky, S.; Flauger, R.; Gorbenko, V.</p> <p>2015-03-01</p> <p>We provide a detailed introduction to a method we recently proposed for calculating the spectrum of excitations of effective strings such as QCD <span class="hlt">flux</span> <span class="hlt">tubes</span>. The method relies on the approximate integrability of the low-energy effective theory describing the <span class="hlt">flux</span> <span class="hlt">tube</span> excitations and is based on the thermodynamic Bethe ansatz. The approximate integrability is a consequence of the Lorentz symmetry of QCD. For excited states, the convergence of the thermodynamic Bethe ansatz technique is significantly better than that of the traditional perturbative approach. We apply the new technique to the lattice spectra for fundamental <span class="hlt">flux</span> <span class="hlt">tubes</span> in gluodynamics in D = 3 + 1 and D = 2 + 1, and to k-strings in gluodynamics in D = 2 + 1. We identify a massive pseudoscalar resonance on the worldsheet of the confining strings in SU(3) gluodynamics in D = 3 + 1, and massive scalar resonances on the worldsheet of k = 2.3 strings in SU(6) gluodynamics in D = 2 + 1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPJP8120C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPJP8120C"><span>Benchmarking Particle-in-Cell drift wave simulations with Eulerian simulations in a <span class="hlt">flux-tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Yang; Parker, Scott; Wan, Weigang; Bravenec, Ronald; Wang, Eric; Candy, Jeff</p> <p>2012-10-01</p> <p>We present the implementation of a <span class="hlt">flux-tube</span> option in the global turbulence code GEM.footnotetextY. Chen and S. E. Parker, J. Comp. Phys. 220, 839 (2007) This is necessary for benchmarking purposes because of the immense complexity involved in comparing global simulations. The global GEM assumes the <span class="hlt">magnetic</span> equilibrium to be completely given. Our initial <span class="hlt">flux-tube</span> implementation simply selects a radial location as the center of the <span class="hlt">flux-tube</span> and a radial size of the <span class="hlt">flux-tube</span>, sets all equilibrium quantities (B, ∇B, T, ∇T, the Jacobian etc.) to be equal to their values at the center of the <span class="hlt">flux-tube</span>, and retains only a linear radial profile of the safety factor needed for boundary conditions. We found good agreement between GEM and GYRO/GS2 for the mode frequency/growth rate in the case of adiabatic electrons, but a difference of ˜15% in the growth rates when kinetic electrons are included. Our goal is to understand the origin of this moderate disagreement. An alternative local geometry model based on a local solution of the Grad-Shafranov equationfootnotetextJ. Candy, Plasma Phys. Control. Fusion 51, 105009 (2009) has been implemented and new benchmarking results from this model will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1223076-signature-fragmentation-color-flux-tube','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1223076-signature-fragmentation-color-flux-tube"><span>Signature of the Fragmentation of a Color <span class="hlt">Flux</span> <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Wong, Cheuk-Yin</p> <p>2015-10-07</p> <p>The production of quark-antiquark pairs along a color <span class="hlt">flux</span> <span class="hlt">tube</span> precedes the fragmentation of the <span class="hlt">tube</span>. Because of the local conservation of momentum and charge, the production of amore » $q$-$$\\bar q$$ pair will lead to correlations of adjacently produced mesons (mostly pions). Adjacently produced pions however can be signalled by the their rapidity difference $$\\Delta y$$ falling within the window of $$|\\Delta y | < 1/(dN_\\pi/dy)$$, on account of the space-time-rapidity ordering of produced pions in a <span class="hlt">flux</span> <span class="hlt">tube</span> fragmentation. Therefore, the local conservation of momentum will lead to a suppression of azimuthal two-pion correlation $$dN/(d\\Delta \\phi\\, d\\Delta y)$$ on the near side at $$(\\Delta \\phi, \\Delta y) \\sim 0$$, but an enhanced azimuthal correlation on the back-to-back, away side at $$(\\Delta \\phi$$$\\sim$$$ \\pi,\\Delta y$$$\\sim$$0). Similarly, in a <span class="hlt">flux</span> <span class="hlt">tube</span> fragmentation, the local conservation of charge will forbid the production of like charge pions within $$|\\Delta y | < 1/(dN_\\pi/dy)$$, but there is no such prohibition for $$|\\Delta y| >1/(dN_\\pi/dy)$$. These properties may be used as the signature for the fragmentation of a color <span class="hlt">flux</span> <span class="hlt">tube</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1223076','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1223076"><span>Signature of the Fragmentation of a Color <span class="hlt">Flux</span> <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wong, Cheuk-Yin</p> <p>2015-10-07</p> <p>The production of quark-antiquark pairs along a color <span class="hlt">flux</span> <span class="hlt">tube</span> precedes the fragmentation of the <span class="hlt">tube</span>. Because of the local conservation of momentum and charge, the production of a $q$-$\\bar q$ pair will lead to correlations of adjacently produced mesons (mostly pions). Adjacently produced pions however can be signalled by the their rapidity difference $\\Delta y$ falling within the window of $|\\Delta y | < 1/(dN_\\pi/dy)$, on account of the space-time-rapidity ordering of produced pions in a <span class="hlt">flux</span> <span class="hlt">tube</span> fragmentation. Therefore, the local conservation of momentum will lead to a suppression of azimuthal two-pion correlation $dN/(d\\Delta \\phi\\, d\\Delta y)$ on the near side at $(\\Delta \\phi, \\Delta y) \\sim 0$, but an enhanced azimuthal correlation on the back-to-back, away side at $(\\Delta \\phi$$\\sim$$ \\pi,\\Delta y$$\\sim$0). Similarly, in a <span class="hlt">flux</span> <span class="hlt">tube</span> fragmentation, the local conservation of charge will forbid the production of like charge pions within $|\\Delta y | < 1/(dN_\\pi/dy)$, but there is no such prohibition for $|\\Delta y| >1/(dN_\\pi/dy)$. These properties may be used as the signature for the fragmentation of a color <span class="hlt">flux</span> <span class="hlt">tube</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJMPA..3150007N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJMPA..3150007N"><span>Regge trajectories of exotic hadrons in the <span class="hlt">flux</span> <span class="hlt">tube</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nandan, Hemwati; Ranjan, Akhilesh</p> <p>2016-02-01</p> <p>We have investigated the Regge trajectories of exotic hadrons by considering different possible pentaquark configurations with finite quark mass in the <span class="hlt">flux</span> <span class="hlt">tube</span> model. Significant deviation is observed in the linear behavior of the Regge trajectories for pentaquark systems in view of the universal value of the Regge slope parameter for hadrons. The modified Regge trajectories are also compared with the available experimental and lattice data. It is observed that the nonlinear Regge trajectories of such pentaquark systems can be well described by the relativistic corrections in view of the current quark masses and the high rotational speed of the quarks at the end of <span class="hlt">flux</span> <span class="hlt">tube</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1354..171P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1354..171P"><span>The Color <span class="hlt">Flux</span> <span class="hlt">Tube</span> as an Effective String</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pepe, Michele</p> <p>2011-05-01</p> <p>We investigate the low-energy regime of the confining string connecting color sources in Yang-Mills theory. First, we present results of the Monte Carlo measurement of the width of the <span class="hlt">flux</span> <span class="hlt">tube</span> between two static quarks in the fundamental representation both at zero and at finite temperature. Then we consider the confining <span class="hlt">flux</span> <span class="hlt">tube</span> connecting color sources in larger representations of the gauge group. For stable strings—the k-strings—we study the Luscher term; for unstable strings we investigate their decay as the distance between the static sources is increased.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22341971','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22341971"><span>Simulations of emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span>. I. The formation of stable coronal <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leake, James E.; Linton, Mark G.; Török, Tibor</p> <p>2013-12-01</p> <p>We present results from three-dimensional visco-resistive magnetohydrodynamic simulations of the emergence of a convection zone <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> into a solar atmosphere containing a pre-existing dipole coronal field, which is orientated to minimize reconnection with the emerging field. We observe that the emergence process is capable of producing a coronal <span class="hlt">flux</span> rope by the transfer of twist from the convection zone, as found in previous simulations. We find that this <span class="hlt">flux</span> rope is stable, with no evidence of a fast rise, and that its ultimate height in the corona is determined by the strength of the pre-existing dipole field. We also find that although the electric currents in the initial convection zone <span class="hlt">flux</span> <span class="hlt">tube</span> are almost perfectly neutralized, the resultant coronal <span class="hlt">flux</span> rope carries a significant net current. These results suggest that <span class="hlt">flux</span> <span class="hlt">tube</span> emergence is capable of creating non-current-neutralized stable <span class="hlt">flux</span> ropes in the corona, tethered by overlying potential fields, a <span class="hlt">magnetic</span> configuration that is believed to be the source of coronal mass ejections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPPT3001V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPPT3001V"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Compression in Plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Velikovich, A. L.</p> <p>2012-10-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> compression (MFC) as a method for producing ultra-high pulsed <span class="hlt">magnetic</span> fields had been originated in the 1950s by Sakharov et al. at Arzamas in the USSR (now VNIIEF, Russia) and by Fowler et al. at Los Alamos in the US. The highest <span class="hlt">magnetic</span> field produced by explosively driven MFC generator, 28 MG, was reported by Boyko et al. of VNIIEF. The idea of using MFC to increase the <span class="hlt">magnetic</span> field in a <span class="hlt">magnetically</span> confined plasma to 3-10 MG, relaxing the strict requirements on the plasma density and Lawson time, gave rise to the research area known as MTF in the US and MAGO in Russia. To make a difference in ICF, a <span class="hlt">magnetic</span> field of ˜100 MG should be generated via MFC by a plasma liner as a part of the capsule compression scenario on a laser or pulsed power facility. This approach was first suggested in mid-1980s by Liberman and Velikovich in the USSR and Felber in the US. It has not been obvious from the start that it could work at all, given that so many mechanisms exist for anomalously fast penetration of <span class="hlt">magnetic</span> field through plasma. And yet, many experiments stimulated by this proposal since 1986, mostly using pulsed-power drivers, demonstrated reasonably good <span class="hlt">flux</span> compression up to ˜42 MG, although diagnostics of <span class="hlt">magnetic</span> fields of such magnitude in HED plasmas is still problematic. The new interest of MFC in plasmas emerged with the advancement of new drivers, diagnostic methods and simulation tools. Experiments on MFC in a deuterium plasma filling a cylindrical plastic liner imploded by OMEGA laser beam led by Knauer, Betti et al. at LLE produced peak fields of 36 MG. The novel MagLIF approach to low-cost, high-efficiency ICF pursued by Herrmann, Slutz, Vesey et al. at Sandia involves pulsed-power-driven MFC to a peak field of ˜130 MG in a DT plasma. A review of the progress, current status and future prospects of MFC in plasmas is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH51C2136G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH51C2136G"><span>Chaos in <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gekelman, W. N.; DeHaas, T.; Van Compernolle, B.</p> <p>2013-12-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes Immersed in a uniform magnetoplasma are observed to twist about themselves, writhe about each other and rotate about a central axis. They are kink unstable and smash into one another as they move. Full three dimensional <span class="hlt">magnetic</span> field and flows are measured at thousands of time steps. Each collision results in <span class="hlt">magnetic</span> field line generation and the generation of a quasi-seperatrix layer and induced electric fields. Three dimensional <span class="hlt">magnetic</span> field lines are computed by conditionally averaging the data using correlation techniques. The permutation entropy1 ,which is related to the Lyapunov exponent, can be calculated from the the time series of the <span class="hlt">magnetic</span> field data (this is also done with flows) and used to calculate the positions of the data on a Jensen Shannon complexity map2. The location of data on this map indicates if the <span class="hlt">magnetic</span> fields are stochastic, or fall into regions of minimal or maximal complexity. The complexity is a function of space and time. The complexity map, and analysis will be explained in the course of the talk. Other types of chaotic dynamical models such as the Lorentz, Gissinger and Henon process also fall on the map and can give a clue to the nature of the <span class="hlt">flux</span> rope turbulence. The ropes fall in the region of the C-H plane where chaotic systems lie. The entropy and complexity change in space and time which reflects the change and possibly type of chaos associated with the ropes. The maps give insight as to the type of chaos (deterministic chaos, fractional diffusion , Levi flights..) and underlying dynamical process. The power spectra of much of the <span class="hlt">magnetic</span> and flow data is exponential and Lorentzian structures in the time domain are embedded in them. Other quantities such as the Hurst exponent are evaluated for both <span class="hlt">magnetic</span> fields and plasma flow. Work Supported by a UC-LANL Lab fund and the Basic Plasma Science Facility which is funded by DOE and NSF. 1) C. Bandt, B. Pompe, Phys. Rev. Lett., 88,174102 (2007) 2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017A%26A...604L...7M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017A%26A...604L...7M"><span><span class="hlt">Magnetic</span> reconnection during eruptive <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mei, Z. X.; Keppens, R.; Roussev, I. I.; Lin, J.</p> <p>2017-08-01</p> <p>Aims: We perform a three-dimensional (3D) high resolution numerical simulation in isothermal magnetohydrodynamics to study the <span class="hlt">magnetic</span> reconnection process in a current sheet (CS) formed during an eruption of a twisted <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope (MFR). Because the twist distribution violates the Kruskal-Shafranov condition, the kink instability occurs, and the MFR is distorted. The centre part of the MFR loses its equilibrium and erupts upward, which leads to the formation of a 3D CS underneath it. Methods: In order to study the <span class="hlt">magnetic</span> reconnection inside the CS in detail, mesh refinement has been used to reduce the numerical diffusion and we estimate a Lundquist number S = 104 in the vicinity of the CS. Results: The refined mesh allows us to resolve fine structures inside the 3D CS: a bifurcating sheet structure signaling the 3D generalization of Petschek slow shocks, some distorted-cylindrical substructures due to the tearing mode instabilities, and two turbulence regions near the upper and the lower tips of the CS. The topological characteristics of the MFR depend sensitively on the observer's viewing angle: it presents as a sigmoid structure, an outwardly expanding MFR with helical distortion, or a flare-CS-coronal mass ejection symbiosis as in 2D <span class="hlt">flux</span>-rope models when observed from the top, the front, or the side. The movie associated to Fig. 2 is available at http://www.aanda.org</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870026815&hterms=shock+tube&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dshock%2Btube','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870026815&hterms=shock+tube&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dshock%2Btube"><span><span class="hlt">Flux</span> limiters. [for shock <span class="hlt">tube</span> flow computation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sweby, P. K.</p> <p>1985-01-01</p> <p>It is well known that first order accurate difference schemes for the numerical solution of conservation laws produce results which suffer from excessive numerical diffusion, classical second order schemes, although giving better resolution, suffer from spurious oscillations. Recently much effect has been put into achieving high resolution without these oscillations, using a variety of techniques. Here one class of such methods, that of <span class="hlt">flux</span> limiting, is outlined together with the TVD constraint used to ensure oscillation free solutions. Brief numerical comparisons of different limiting functions are also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSH42A..02I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSH42A..02I"><span>Unsteady wandering <span class="hlt">magnetic</span> field lines, turbulence and laboratory <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Intrator, T.; Sears, J.; Weber, T.; Liu, D.; Pulliam, D.; Lazarian, A.</p> <p>2011-12-01</p> <p>We describe earth bound laboratory experiment investigations of patchy, unsteady, bursty, patchy <span class="hlt">magnetic</span> field structures that are unifying features of <span class="hlt">magnetic</span> reconnection and turbulence in helio, space and astro physics. Macroscopic field lines occupy cross sectional areas, fill up three dimensional (3D) volumes as <span class="hlt">flux</span> <span class="hlt">tubes</span>. They contain mass with Newtonian dynamics that follow magneto-hydro-dynamic (MHD) equations of motion. <span class="hlt">Flux</span> rope geometry can be ubiquitous in laminar reconnection sheet geometries that are themselves unstable to formation of secondary "islands" that in 3D are really <span class="hlt">flux</span> ropes. <span class="hlt">Flux</span> ropes are ubiquitous structures on the sun and the rest of the heliosphere. Understanding the dynamics of <span class="hlt">flux</span> ropes and their mutual interactions offers the key to many important astrophysical phenomena, including <span class="hlt">magnetic</span> reconnection and turbulence. We describe laboratory investigations on RSX, where 3D interaction of <span class="hlt">flux</span> ropes can be studied in great detail. We use experimental probes inside the the <span class="hlt">flux</span> ropes to measure the <span class="hlt">magnetic</span> and electric fields, current density, density, temperatures, pressure, and electrostatic and vector plasma potentials. Macroscopic <span class="hlt">magnetic</span> field lines, unsteady wandering characteristics, and dynamic objects with structure down to the dissipation scale length can be traced from data sets in a 3D volume. Computational approaches are finally able to tackle simple 3D systems and we sketch some intriguing simulation results that are consistent with 3D extensions of typical 2D cartoons for <span class="hlt">magnetic</span> reconnection and turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6580031','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6580031"><span>Adjustable rare earth quadrupole drift <span class="hlt">tube</span> <span class="hlt">magnets</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Feinberg, B.; Tanabe, J.; Halbach, K.; Koehler, G.; Green, M.I.</p> <p>1987-03-01</p> <p>A prototype permanent-<span class="hlt">magnet</span> drift <span class="hlt">tube</span> quadrupole with adjustable field strength has been constructed and tested. The <span class="hlt">magnet</span> uses iron pole pieces to provide the required field shape along with rare earth permanent-<span class="hlt">magnet</span> material (samarium cobalt) to energize the <span class="hlt">magnet</span>. A unique feature of the configuration is the adjustability of the field, accomplished by rotating the outer rings consisting of permanent <span class="hlt">magnets</span> and iron. In contrast with a previous prototype <span class="hlt">magnet</span>, this new design uses ball bearings in place of slide bearings to eliminate potential failures. The rotation is now achieved with a bevel gear mechanism. The prototype design also incorporates a new drift <span class="hlt">tube</span> shell vacuum seal to allow easy disassembly. Tests were made of the <span class="hlt">magnetic</span> properties and the mechanical performance of this <span class="hlt">magnet</span>. Field errors are extremely small, and the <span class="hlt">magnet</span> passed an accelerated ten year lifetime test. It is planned to use this type of <span class="hlt">magnet</span> to replace 24 of the SuperHILAC prestripper drift <span class="hlt">tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15783454','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15783454"><span>Lagrange mesh, relativistic <span class="hlt">flux</span> <span class="hlt">tube</span>, and rotating string.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Buisseret, Fabien; Semay, Claude</p> <p>2005-02-01</p> <p>The Lagrange mesh method is a very accurate and simple procedure to compute eigenvalues and eigenfunctions of nonrelativistic and semirelativistic Hamiltonians. We show here that it can be used successfully to solve the equations of both the relativistic <span class="hlt">flux</span> <span class="hlt">tube</span> model and the rotating string model, in the symmetric case. Verifications of the convergence of the method are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DPPPI3006Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DPPPI3006Y"><span>Quasi-steady multiple <span class="hlt">flux</span> <span class="hlt">tubes</span> induced by localized current perturbation in toroidal plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yun, Gunsu</p> <p>2015-11-01</p> <p>Quasi-steady helical modes with dual, triple, or more <span class="hlt">flux</span> <span class="hlt">tubes</span> are easily produced by localized current drive in the core of sawtoothing plasma on the KSTAR tokamak. Individual <span class="hlt">flux</span> <span class="hlt">tubes</span> have m / n = 1 / 1 helicity, co-rotate around the <span class="hlt">magnetic</span> axis, and later merge into a single m = 1 mode. The merged mode eventually crashes with rapid collapse of the core pressure and the next cycle repeats the same pattern, exhibiting sawtooth-like oscillations in the core pressure. The generation mechanism of multiple <span class="hlt">flux</span> <span class="hlt">tubes</span> (MFTs) has been studied in two different approaches to understand the observed trend that the number of <span class="hlt">flux</span> <span class="hlt">tubes</span> increases as the current drive location moves away from the <span class="hlt">magnetic</span> axis up to about the <span class="hlt">magnetic</span> surface of the safety factor q = 1 at the mode collapse: (1) nonlinear reduced MHD simulation with a localized current source modeling the time-varying interaction between the current source and <span class="hlt">flux</span> <span class="hlt">tubes</span> and (2) linear MHD simulation with a prescribed q profile with a radially localized current blip. Both studies show that MFTs can be produced only in plasmas with nearly flat q profile close to unity, suggesting the collapse of the m = 1 mode (i.e., sawtooth crash) is complete. Recent observation of long-lived MFTs induced by localized current drive in non-sawtoothing plasma suggests that q profile evolution toward lower- m instability is required for the merging and crash of MFTs. Work supported by the National Research Foundation of Korea, US D.O.E., and Japan Society for the Promotion of Science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22521914','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22521914"><span>MULTI-PARAMETRIC STUDY OF RISING 3D BUOYANT <span class="hlt">FLUX</span> <span class="hlt">TUBES</span> IN AN ADIABATIC STRATIFICATION USING AMR</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martínez-Sykora, Juan; Cheung, Mark C. M.; Moreno-Insertis, Fernando</p> <p>2015-11-20</p> <p>We study the buoyant rise of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> embedded in an adiabatic stratification using two-and three-dimensional, magnetohydrodynamic simulations. We analyze the dependence of the <span class="hlt">tube</span> evolution on the field line twist and on the curvature of the <span class="hlt">tube</span> axis in different diffusion regimes. To be able to achieve a comparatively high spatial resolution we use the FLASH code, which has a built-in Adaptive Mesh Refinement (AMR) capability. Our 3D experiments reach Reynolds numbers that permit a reasonable comparison of the results with those of previous 2D simulations. When the experiments are run without AMR, hence with a comparatively large diffusivity, the amount of longitudinal <span class="hlt">magnetic</span> <span class="hlt">flux</span> retained inside the <span class="hlt">tube</span> increases with the curvature of the <span class="hlt">tube</span> axis. However, when a low-diffusion regime is reached by using the AMR algorithms, the <span class="hlt">magnetic</span> twist is able to prevent the splitting of the <span class="hlt">magnetic</span> loop into vortex <span class="hlt">tubes</span> and the loop curvature does not play any significant role. We detect the generation of vorticity in the main body of the <span class="hlt">tube</span> of opposite sign on the opposite sides of the apex. This is a consequence of the inhomogeneity of the azimuthal component of the field on the <span class="hlt">flux</span> surfaces. The lift force associated with this global vorticity makes the flanks of the <span class="hlt">tube</span> move away from their initial vertical plane in an antisymmetric fashion. The trajectories have an oscillatory motion superimposed, due to the shedding of vortex rolls to the wake, which creates a Von Karman street.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22039407','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22039407"><span>SURFACE ALFVEN WAVES IN SOLAR <span class="hlt">FLUX</span> <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goossens, M.; Andries, J.; Soler, R.; Van Doorsselaere, T.; Arregui, I.; Terradas, J.</p> <p>2012-07-10</p> <p>Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. Alfven waves and magneto-sonic waves are particular classes of MHD waves. These wave modes are clearly different and have pure properties in uniform plasmas of infinite extent only. Due to plasma non-uniformity, MHD waves have mixed properties and cannot be classified as pure Alfven or magneto-sonic waves. However, vorticity is a quantity unequivocally related to Alfven waves as compression is for magneto-sonic waves. Here, we investigate MHD waves superimposed on a one-dimensional non-uniform straight cylinder with constant <span class="hlt">magnetic</span> field. For a piecewise constant density profile, we find that the fundamental radial modes of the non-axisymmetric waves have the same properties as surface Alfven waves at a true discontinuity in density. Contrary to the classic Alfven waves in a uniform plasma of infinite extent, vorticity is zero everywhere except at the cylinder boundary. If the discontinuity in density is replaced with a continuous variation of density, vorticity is spread out over the whole interval with non-uniform density. The fundamental radial modes of the non-axisymmetric waves do not need compression to exist unlike the radial overtones. In thin <span class="hlt">magnetic</span> cylinders, the fundamental radial modes of the non-axisymmetric waves with phase velocities between the internal and the external Alfven velocities can be considered as surface Alfven waves. On the contrary, the radial overtones can be related to fast-like magneto-sonic modes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhD...49G5003K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhD...49G5003K"><span>A time-varying <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kibret, B.; Premaratne, M.; Lewis, P. M.; Thomson, R.; Fitzgerald, P. B.</p> <p>2016-08-01</p> <p>It is known that diverse technological applications require the use of focused <span class="hlt">magnetic</span> fields. This has driven the quest for controlling the <span class="hlt">magnetic</span> field. Recently, the principles in transformation optics and metamaterials have allowed the realization of practical static <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrators. Extending such progress, here, we propose a time-varying <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrator cylindrical shell that uses electric conductors and ferromagnetic materials to guide <span class="hlt">magnetic</span> <span class="hlt">flux</span> to its center. Its performance is discussed based on finite-element simulation results. Our proposed design has potential applications in <span class="hlt">magnetic</span> sensors, medical devices, wireless power transfer, and near-field wireless communications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970025515','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970025515"><span>Achieving Zero Current for Polar Wind Outflow on Open <span class="hlt">Flux</span> <span class="hlt">Tubes</span> Subjected to Large Photoelectron <span class="hlt">Fluxes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, G. R.; Khazanov, G.; Horwitz, J. L.</p> <p>1997-01-01</p> <p>In this study we investigate how the condition of zero current on open <span class="hlt">flux</span> <span class="hlt">tubes</span> with polar wind outflow, subjected to large photoelectron <span class="hlt">fluxes</span>, can be achieved. We employ a steady state collisionless semikinetic model to determine the density profiles of O(+), H(+), thermal electrons and photoelectrons coming from the ionosphere along with H(+), ions and electrons coming from the magnetosphere. The model solution attains a potential distribution which both satisfies the condition of charge neutrality and zero current. For the range of parameters considered in this study we find that a 45-60 volt discontinuous potential drop may develop to reflect most of the photoelectrons back toward the ionosphere. This develops because the downward <span class="hlt">flux</span> of electrons from the magnetosphere to the ionosphere on typical open <span class="hlt">flux</span> <span class="hlt">tubes</span> (e.g. the polar rain) appears to be insufficient to balance the photoelectron <span class="hlt">flux</span> from the ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH14B..07V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH14B..07V"><span><span class="hlt">Flux</span> <span class="hlt">tubes</span> embedded into reconnection outflows in the solar wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Voros, Z.; Zaqarashvili, T.; Sasunov, Y.; Narita, Y.</p> <p>2015-12-01</p> <p>Reconnection exhausts in the solar wind are usually interpreted in terms of a quasi-stationary Petschek-type reconnection model. Accordingly, within a region of <span class="hlt">magnetic</span> field reversal, the wedge-shaped, Alfvenic accelerated plasma outflow is bounded by layers containing (anti-) correlated components of speed and <span class="hlt">magnetic</span> field fluctuations. However, time-dependent impulsive reconnection can generate <span class="hlt">flux</span> ropes embedded into accelerated outflows. Reconnection associated moving <span class="hlt">flux</span> ropes or plasmoids are frequently observed in the Earth's magnetotail, while similar observations are missing in the solar wind. We present the first observations of small-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes associated with reconnection exhausts in the solar wind, using the data from the WIND probe. We argue that the interaction of moving <span class="hlt">flux</span> ropes with the background plasma can generate turbulence leading finally to the local heating of the solar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720041698&hterms=metallic+glass&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmetallic%2Bglass','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720041698&hterms=metallic+glass&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dmetallic%2Bglass"><span>Low thermal <span class="hlt">flux</span> glass-fiber <span class="hlt">tubing</span> for cryogenic service.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, C. A.; Pharo, T. J., Jr.; Phillips, J. M.</p> <p>1972-01-01</p> <p>Study of thin metallic liners which provide leak-free service in cryogenic propulsion plumbing systems and are overwrapped with a glass-fiber composite that provides strength and protection from handling damage. The composite <span class="hlt">tube</span> is lightweight, strong, and has a very low thermal <span class="hlt">flux</span>. The resultant reduced boiloff of stored cryogenic propellants yields a substantial weight savings for long-term missions (seven days or greater). Twelve styles of <span class="hlt">tubing</span> ranging from 1/2 to 5 in. in diameter were fabricated and tested with excellent results for most of the concepts at operating temperatures from +70 to -423 F and operating pressures up to 3000 psi.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1336585','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1336585"><span>Dynamics of Quarks in a 2D <span class="hlt">Flux</span> <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Koshelkin, Andrey V.; Wong, Cheuk-Yin</p> <p>2015-01-01</p> <p>On the basis of a compactification of the (3+1) into (1+1) dimensional space-time [1], the quark states inside the 2D <span class="hlt">flux</span> <span class="hlt">tube</span> are studied for the case of a linear transverse confining potential. The derived states are classified by both the projections of the orbital momentum and the spin along the <span class="hlt">tube</span> direction. The spectrum of the fermion states is evaluated. It is found that the energy eigenvalues of the quarks appear to be approximately related to the square root of the eigenvalues of the two-dimensional harmonic oscillator.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PPCF...56f0301L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PPCF...56f0301L"><span>Self-organization in <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukin, Vyacheslav S.</p> <p>2014-06-01</p> <p>This cross-disciplinary special issue on 'Self-organization in <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes' follows in the footsteps of another collection of manuscripts dedicated to the subject of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes, a volume on 'Physics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes' published in the American Geophysical Union's Geophysical Monograph Series in 1990 [1]. Twenty-four years later, this special issue, composed of invited original contributions highlighting ongoing research on the physics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in astrophysical, space and laboratory plasmas, can be considered an update on our state of understanding of this fundamental constituent of any <span class="hlt">magnetized</span> plasma. Furthermore, by inviting contributions from research groups focused on the study of the origins and properties of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in a variety of different environments, we have attempted to underline both the diversity of and the commonalities among <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes throughout the solar system and, indeed, the universe. So, what is a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope? The answer will undoubtedly depend on whom you ask. A <span class="hlt">flux</span> rope can be as narrow as a few Larmor radii and as wide as the Sun (see, e.g., the contributions by Heli Hietala et al and by Angelous Vourlidas). As described below by Ward Manchester IV et al , they can stretch from the Sun to the Earth in the form of interplanetary coronal mass ejections. Or, as in the Swarthmore Spheromak Experiment described by David Schaffner et al , they can fit into a meter-long laboratory device tended by college students. They can be helical and line-tied (see, e.g., Walter Gekelman et al or J Sears et al ), or toroidal and periodic (see, e.g., John O'Bryan et al or Philippa Browning et al ). They can form in the low plasma beta environment of the solar corona (Tibor Török et al ), the order unity beta plasmas of the solar wind (Stefan Eriksson et al ) and the plasma pressure dominated stellar convection zones (Nicholas Nelson and Mark Miesch). In this special issue, Setthivoine You</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890000221&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmagnetic%2Bcooling','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890000221&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmagnetic%2Bcooling"><span><span class="hlt">Magnetic-Flux</span>-Compression Cooling Using Superconductors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Strayer, Donald M.; Israelsson, Ulf E.; Elleman, Daniel D.</p> <p>1989-01-01</p> <p>Proposed <span class="hlt">magnetic-flux</span>-compression refrigeration system produces final-stage temperatures below 4.2 K. More efficient than mechanical and sorption refrigerators at temperatures in this range. Weighs less than comparable liquid-helium-cooled superconducting <span class="hlt">magnetic</span> refrigeration systems operating below 4.2 K. <span class="hlt">Magnetic-flux</span>-compression cooling stage combines advantages of newly discovered superconductors with those of cooling by <span class="hlt">magnetization</span> and demagnetization of paramagnetic salts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040111425&hterms=Steel+Structures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSteel%2BStructures','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040111425&hterms=Steel+Structures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSteel%2BStructures"><span>Detection of Cracks at Welds in Steel <span class="hlt">Tubing</span> Using <span class="hlt">Flux</span> Focusing Electromagnetic Probe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Simpson, John; Namkung, Min</p> <p>1994-01-01</p> <p>The inspection of weldments in critical pressure vessel joints is a major concern in the nuclear power industry. Corrosive environments can speed the fatigue process and access to the critical area is often limited. Eddy current techniques have begun to be used to help overcome these obstacles [1]. As direct contact and couplants are not required, remote areas can be inspected by simply snaking an eddy current coil into the intake <span class="hlt">tube</span> of the vessel. The drawback of the eddy current method has been the high sensitivity to small changes in the conductivity and permeability of the test piece which are known to vary at weldments [1]. The flaw detection mechanism of the <span class="hlt">flux</span> focusing electromagnetic probe can help alleviate these difficulties and provide a unique capability for detecting longitudinal fatigue cracks in critical <span class="hlt">tube</span> structures. The <span class="hlt">Flux</span> Focusing Electromagnetic Flaw Detector, originally invented for the detection of fatigue and corrosion damage in aluminum plates [2-3], has been adapted for use in testing steel <span class="hlt">tubing</span> for longitudinal fatigue cracks. The modified design allows for the probe to be placed axisymmetrically into the <span class="hlt">tubing</span>, inducing eddy currents in the <span class="hlt">tube</span> wall. The pickup coil of the probe is fixed slightly below the primary windings and is rotated 90 so that its axis is normal to the <span class="hlt">tube</span> wall. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> of the primary coil is focused through the use of ferromagnetic material so that in the absence of fatigue damage there will be no <span class="hlt">flux</span> linkage with the pickup coil. The presence of a longitudinal fatigue crack will cause the eddy currents induced in the <span class="hlt">tube</span> wall to flow around the flaw and directly under the pickup coil. The <span class="hlt">magnetic</span> field associated with these currents will then link the pickup coil and an unambiguous increase in the output voltage of the probe will be measured. The use of the <span class="hlt">flux</span> focusing electromagnetic probe is especially suited for the detection of flaws originating at or near <span class="hlt">tube</span> welds. The probe is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040111425&hterms=Elements+electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DElements%2Belectromagnetic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040111425&hterms=Elements+electromagnetic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DElements%2Belectromagnetic"><span>Detection of Cracks at Welds in Steel <span class="hlt">Tubing</span> Using <span class="hlt">Flux</span> Focusing Electromagnetic Probe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Simpson, John; Namkung, Min</p> <p>1994-01-01</p> <p>The inspection of weldments in critical pressure vessel joints is a major concern in the nuclear power industry. Corrosive environments can speed the fatigue process and access to the critical area is often limited. Eddy current techniques have begun to be used to help overcome these obstacles [1]. As direct contact and couplants are not required, remote areas can be inspected by simply snaking an eddy current coil into the intake <span class="hlt">tube</span> of the vessel. The drawback of the eddy current method has been the high sensitivity to small changes in the conductivity and permeability of the test piece which are known to vary at weldments [1]. The flaw detection mechanism of the <span class="hlt">flux</span> focusing electromagnetic probe can help alleviate these difficulties and provide a unique capability for detecting longitudinal fatigue cracks in critical <span class="hlt">tube</span> structures. The <span class="hlt">Flux</span> Focusing Electromagnetic Flaw Detector, originally invented for the detection of fatigue and corrosion damage in aluminum plates [2-3], has been adapted for use in testing steel <span class="hlt">tubing</span> for longitudinal fatigue cracks. The modified design allows for the probe to be placed axisymmetrically into the <span class="hlt">tubing</span>, inducing eddy currents in the <span class="hlt">tube</span> wall. The pickup coil of the probe is fixed slightly below the primary windings and is rotated 90 so that its axis is normal to the <span class="hlt">tube</span> wall. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> of the primary coil is focused through the use of ferromagnetic material so that in the absence of fatigue damage there will be no <span class="hlt">flux</span> linkage with the pickup coil. The presence of a longitudinal fatigue crack will cause the eddy currents induced in the <span class="hlt">tube</span> wall to flow around the flaw and directly under the pickup coil. The <span class="hlt">magnetic</span> field associated with these currents will then link the pickup coil and an unambiguous increase in the output voltage of the probe will be measured. The use of the <span class="hlt">flux</span> focusing electromagnetic probe is especially suited for the detection of flaws originating at or near <span class="hlt">tube</span> welds. The probe is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22092185','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22092185"><span>SCATTERING OF THE f-MODE BY SMALL <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> ELEMENTS FROM OBSERVATIONS AND NUMERICAL SIMULATIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Felipe, T.; Braun, D.; Crouch, A.; Birch, A.</p> <p>2012-10-01</p> <p>The scattering of f-modes by <span class="hlt">magnetic</span> <span class="hlt">tubes</span> is analyzed using three-dimensional numerical simulations. An f-mode wave packet is propagated through a solar atmosphere embedded with three different <span class="hlt">flux</span> <span class="hlt">tube</span> models that differ in radius and total <span class="hlt">magnetic</span> <span class="hlt">flux</span>. A quiet-Sun simulation without a <span class="hlt">tube</span> present is also performed as a reference. Waves are excited inside the <span class="hlt">flux</span> <span class="hlt">tube</span> and propagate along the field lines, and jacket modes are generated in the surroundings of the <span class="hlt">flux</span> <span class="hlt">tube</span>, carrying 40% as much energy as the <span class="hlt">tube</span> modes. The resulting scattered wave is mainly an f-mode composed of a mixture of m = 0 and m = {+-}1 modes. The amplitude of the scattered wave approximately scales with the <span class="hlt">magnetic</span> <span class="hlt">flux</span>. A small amount of power is scattered into the p{sub 1}-mode. We have evaluated the absorption and phase shift from a Fourier-Hankel decomposition of the photospheric vertical velocities. They are compared with the results obtained from the ensemble average of 3400 small <span class="hlt">magnetic</span> elements observed in high-resolution MDI Doppler datacubes. The comparison shows that the observed dependence of the phase shift with wavenumber can be matched reasonably well with the simulated <span class="hlt">flux</span> <span class="hlt">tube</span> model. The observed variation of the phase shifts with the azimuthal order m appears to depend on details of the ensemble averaging, including possible motions of the <span class="hlt">magnetic</span> elements and asymmetrically shaped elements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930071260&hterms=Shibata&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DShibata%252C%2BM','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930071260&hterms=Shibata&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DShibata%252C%2BM"><span>Three-dimensional magnetohydrodynamics of the emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the solar atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Matsumoto, R.; Tajima, T.; Shibata, K.; Kaisig, M.</p> <p>1993-01-01</p> <p>The nonlinear evolution of an emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> or sheet in the solar atmosphere is studied through 3D MHD simulations. In the initial state, a horizontal <span class="hlt">magnetic</span> <span class="hlt">flux</span> sheet or <span class="hlt">tube</span> is assumed to be embedded at the bottom of MHD two isothermal gas layers, which approximate the solar photosphere/chromosphere and the corona. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> sheet or <span class="hlt">tube</span> is unstable against the undular mode of the <span class="hlt">magnetic</span> buoyancy instability. The <span class="hlt">magnetic</span> loop rises due to the linear and then later nonlinear instabilities caused by the buoyancy enhanced by precipitating the gas along <span class="hlt">magnetic</span> field lines. We find by 3D simulation that during the ascendance of loops the bundle of <span class="hlt">flux</span> <span class="hlt">tubes</span> or even the <span class="hlt">flux</span> sheet develops into dense gas filaments pinched between <span class="hlt">magnetic</span> loops. The interchange modes help produce a fine fiber <span class="hlt">flux</span> structure perpendicular to the <span class="hlt">magnetic</span> field direction in the linear stage, while the undular modes determine the overall buoyant loop structure. The expansion of such a bundle of <span class="hlt">magnetic</span> loops follows the self-similar behavior observed in 2D cases studied earlier. Our study finds the threshold <span class="hlt">flux</span> for arch filament system (AFS) formation to be about 0.3 x 10 exp 20 Mx.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910059815&hterms=Sound+waves&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSound%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910059815&hterms=Sound+waves&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSound%2Bwaves"><span>Resonant behaviour of MHD waves on <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. I - Connection formulae at the resonant surfaces. II - Absorption of sound waves by sunspots</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sakurai, Takashi; Goossens, Marcel; Hollweg, Joseph V.</p> <p>1991-01-01</p> <p>The present method of addressing the resonance problems that emerge in such MHD phenomena as the resonant absorption of waves at the Alfven resonance point avoids solving the fourth-order differential equation of dissipative MHD by recourse to connection formulae across the dissipation layer. In the second part of this investigation, the absorption of solar 5-min oscillations by sunspots is interpreted as the resonant absorption of sounds by a <span class="hlt">magnetic</span> cylinder. The absorption coefficient is interpreted (1) analytically, under certain simplifying assumptions, and numerically, under more general conditions. The observed absorption coefficient magnitude is explained over suitable parameter ranges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009CoPhC.180.2650P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009CoPhC.180.2650P"><span>The nonlinear gyro-kinetic <span class="hlt">flux</span> <span class="hlt">tube</span> code GKW</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peeters, A. G.; Camenen, Y.; Casson, F. J.; Hornsby, W. A.; Snodin, A. P.; Strintzi, D.; Szepesi, G.</p> <p>2009-12-01</p> <p>A new nonlinear gyro-kinetic <span class="hlt">flux</span> <span class="hlt">tube</span> code (GKW) for the simulation of micro instabilities and turbulence in <span class="hlt">magnetic</span> confinement plasmas is presented in this paper. The code incorporates all physics effects that can be expected from a state of the art gyro-kinetic simulation code in the local limit: kinetic electrons, electromagnetic effects, collisions, full general geometry with a coupling to a MHD equilibrium code, and E×B shearing. In addition the physics of plasma rotation has been implemented through a formulation of the gyro-kinetic equation in the co-moving system. The gyro-kinetic model is five-dimensional and requires a massive parallel approach. GKW has been parallelised using MPI and scales well up to 8192+ cores. The paper presents the set of equations solved, the numerical methods, the code structure, and the essential benchmarks. Program summaryProgram title: GKW Catalogue identifier: AEES_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEES_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL v3 No. of lines in distributed program, including test data, etc.: 29 998 No. of bytes in distributed program, including test data, etc.: 206 943 Distribution format: tar.gz Programming language: Fortran 95 Computer: Not computer specific Operating system: Any for which a Fortran 95 compiler is available Has the code been vectorised or parallelised?: Yes. The program can efficiently utilise 8192+ processors, depending on problem and available computer. 128 processors is reasonable for a typical nonlinear kinetic run on the latest x86-64 machines. RAM:˜128 MB-1 GB for a linear run; 25 GB for typical nonlinear kinetic run (30 million grid points) Classification: 19.8, 19.9, 19.11 External routines: None required, although the functionality of the program is somewhat limited without a MPI implementation (preferably MPI-2) and the FFTW3 library. Nature of problem: Five</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IAUS..328...85W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IAUS..328...85W"><span>The Suppression and Promotion of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Emergence in Fully Convective Stars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weber, Maria A.; Browning, Matthew K.; Boardman, Suzannah; Clarke, Joshua; Pugsley, Samuel; Townsend, Edward</p> <p>2017-10-01</p> <p>Evidence of surface <span class="hlt">magnetism</span> is now observed on an increasing number of cool stars. The detailed manner by which dynamo-generated <span class="hlt">magnetic</span> fields giving rise to starspots traverse the convection zone still remains unclear. Some insight into this <span class="hlt">flux</span> emergence mechanism has been gained by assuming bundles of <span class="hlt">magnetic</span> field can be represented by idealized thin <span class="hlt">flux</span> <span class="hlt">tubes</span> (TFTs). Weber & Browning (2016) have recently investigated how individual <span class="hlt">flux</span> <span class="hlt">tubes</span> might evolve in a 0.3M⊙ M dwarf by effectively embedding TFTs in time-dependent flows representative of a fully convective star. We expand upon this work by initiating <span class="hlt">flux</span> <span class="hlt">tubes</span> at various depths in the upper ~50-75% of the star in order to sample the differing convective flow pattern and differential rotation across this region. Specifically, we comment on the role of differential rotation and time-varying flows in both the suppression and promotion of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5008696','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5008696"><span>Regulation of the interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McComas, D.J.; Gosling, J.T.; Phillips, J.L.</p> <p>1991-01-01</p> <p>In this study we use a recently developed technique for measuring the 2-D <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the ecliptic plane to examine (1) the long term variation of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> in interplanetary space and (2) the apparent rate at which coronal mass ejections (CMEs) may be opening new <span class="hlt">flux</span> from the Sun. Since there is a substantial variation ({approximately}50%) of the <span class="hlt">flux</span> in the ecliptic plane over the solar cycle, we conclude that there must be some means whereby new <span class="hlt">flux</span> can be opened from the Sun and previously open <span class="hlt">magnetic</span> <span class="hlt">flux</span> can be closed off. We briefly describe recently discovered coronal disconnections events which could serve to close off previously open <span class="hlt">magnetic</span> <span class="hlt">flux</span>. CMEs appear to retain at least partial <span class="hlt">magnetic</span> connection to the Sun and hence open new <span class="hlt">flux</span>, while disconnections appear to be likely signatures of the process that returns closed <span class="hlt">flux</span> to the Sun; the combination of these processes could regulate the amount of open <span class="hlt">magnetic</span> <span class="hlt">flux</span> in interplanetary space. 6 refs., 3 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21307945','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21307945"><span>THE EMERGENCE OF A TWISTED <span class="hlt">FLUX</span> <span class="hlt">TUBE</span> INTO THE SOLAR ATMOSPHERE: SUNSPOT ROTATIONS AND THE FORMATION OF A CORONAL <span class="hlt">FLUX</span> ROPE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fan, Y.</p> <p>2009-06-01</p> <p>We present a three-dimensional simulation of the dynamic emergence of a twisted <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> from the top layer of the solar convection zone into the solar atmosphere and corona. It is found that after a brief initial stage of <span class="hlt">flux</span> emergence during which the two polarities of the bipolar region become separated and the <span class="hlt">tubes</span> intersecting the photosphere become vertical, significant rotational motion sets in within each polarity. The rotational motions of the two polarities are found to twist up the inner field lines of the emerged fields such that they change their orientation into an inverse configuration (i.e., pointing from the negative polarity to the positive polarity over the neutral line). As a result, a <span class="hlt">flux</span> rope with sigmoid-shaped, dipped core fields forms in the corona, and the center of the <span class="hlt">flux</span> rope rises in the corona with increasing velocity as the twisting of the <span class="hlt">flux</span> rope footpoints continues. The rotational motion in the two polarities is a result of propagation of nonlinear torsional Alfven waves along the <span class="hlt">flux</span> <span class="hlt">tube</span>, which transports significant twist from the <span class="hlt">tube</span>'s interior portion toward its expanded coronal portion. This is a basic process whereby twisted <span class="hlt">flux</span> ropes are developed in the corona with increasing twist and <span class="hlt">magnetic</span> energy, leading up to solar eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013RScI...84h5120S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013RScI...84h5120S"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> amplification by Lenz lenses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schoenmaker, J.; Pirota, K. R.; Teixeira, J. C.</p> <p>2013-08-01</p> <p>Tailoring <span class="hlt">magnetic</span> <span class="hlt">flux</span> distribution is highly desirable in a wide range of applications such as <span class="hlt">magnetic</span> sensors and biomedicine. In this paper we study the manipulation of induced currents in passive devices in order to engineer the distribution of <span class="hlt">magnetic</span> <span class="hlt">flux</span> intensity in a given region. We propose two different approaches, one based on especially designed wire loops (Lenz law) and the other based on solid conductive pieces (eddy currents). The gain of such devices is mainly determined by geometry giving perspective of high amplification. We consistently modeled, simulated, and executed the proposed devices. Doubled <span class="hlt">magnetic</span> <span class="hlt">flux</span> intensity is demonstrated experimentally for a moderate aspect ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...813..112T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...813..112T"><span>Numerical Study on the Emergence of Kinked <span class="hlt">Flux</span> <span class="hlt">Tube</span> for Understanding of Possible Origin of δ-spot Regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takasao, Shinsuke; Fan, Yuhong; Cheung, Mark C. M.; Shibata, Kazunari</p> <p>2015-11-01</p> <p>We carried out an magnetohydrodynamic simulation where a subsurface twisted kink-unstable <span class="hlt">flux</span> <span class="hlt">tube</span> emerges from the solar interior to the corona. Unlike the previous expectations based on the bodily emergence of a knotted <span class="hlt">tube</span>, we found that the kinked <span class="hlt">tube</span> can spontaneously form a complex quadrupole structure at the photosphere. Due to the development of the kink instability before the emergence, the <span class="hlt">magnetic</span> twist at the kinked apex of the <span class="hlt">tube</span> is greatly reduced, although the other parts of the <span class="hlt">tube</span> are still strongly twisted. This leads to the formation of a complex quadrupole structure: a pair of the coherent, strongly twisted spots and a narrow complex bipolar pair between it. The quadrupole is formed by the submergence of a portion of emerged <span class="hlt">magnetic</span> fields. This result is relevant for understanding the origin of the complex multipolar δ-spot regions that have a strong <span class="hlt">magnetic</span> shear and emerge with polarity orientations not following Hale-Nicholson and Joy Laws.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22521922','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22521922"><span>NUMERICAL STUDY ON THE EMERGENCE OF KINKED <span class="hlt">FLUX</span> <span class="hlt">TUBE</span> FOR UNDERSTANDING OF POSSIBLE ORIGIN OF δ-SPOT REGIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Takasao, Shinsuke; Shibata, Kazunari; Fan, Yuhong; Cheung, Mark C. M.</p> <p>2015-11-10</p> <p>We carried out an magnetohydrodynamic simulation where a subsurface twisted kink-unstable <span class="hlt">flux</span> <span class="hlt">tube</span> emerges from the solar interior to the corona. Unlike the previous expectations based on the bodily emergence of a knotted <span class="hlt">tube</span>, we found that the kinked <span class="hlt">tube</span> can spontaneously form a complex quadrupole structure at the photosphere. Due to the development of the kink instability before the emergence, the <span class="hlt">magnetic</span> twist at the kinked apex of the <span class="hlt">tube</span> is greatly reduced, although the other parts of the <span class="hlt">tube</span> are still strongly twisted. This leads to the formation of a complex quadrupole structure: a pair of the coherent, strongly twisted spots and a narrow complex bipolar pair between it. The quadrupole is formed by the submergence of a portion of emerged <span class="hlt">magnetic</span> fields. This result is relevant for understanding the origin of the complex multipolar δ-spot regions that have a strong <span class="hlt">magnetic</span> shear and emerge with polarity orientations not following Hale-Nicholson and Joy Laws.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21587319','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21587319"><span>THE RISE OF ACTIVE REGION <span class="hlt">FLUX</span> <span class="hlt">TUBES</span> IN THE TURBULENT SOLAR CONVECTIVE ENVELOPE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Weber, Maria A.; Fan Yuhong; Miesch, Mark S.</p> <p>2011-11-01</p> <p>We use a thin <span class="hlt">flux</span> <span class="hlt">tube</span> model in a rotating spherical shell of turbulent convective flows to study how active region scale <span class="hlt">flux</span> <span class="hlt">tubes</span> rise buoyantly from the bottom of the convection zone to near the solar surface. We investigate toroidal <span class="hlt">flux</span> <span class="hlt">tubes</span> at the base of the convection zone with field strengths ranging from 15 kG to 100 kG at initial latitudes ranging from 1{sup 0} to 40{sup 0} with a total <span class="hlt">flux</span> of 10{sup 22} Mx. We find that the dynamic evolution of the <span class="hlt">flux</span> <span class="hlt">tube</span> changes from convection dominated to <span class="hlt">magnetic</span> buoyancy dominated as the initial field strength increases from 15 kG to 100 kG. At 100 kG, the development of {Omega}-shaped rising loops is mainly controlled by the growth of the <span class="hlt">magnetic</span> buoyancy instability. However, at low field strengths of 15 kG, the development of rising {Omega}-shaped loops is largely controlled by convective flows, and properties of the emerging loops are significantly changed compared to previous results in the absence of convection. With convection, rise times are drastically reduced (from years to a few months), loops are able to emerge at low latitudes, and tilt angles of emerging loops are consistent with Joy's law for initial field strengths of {approx}>40 kG. We also examine other asymmetries that develop between the leading and following legs of the emerging loops. Taking all the results together, we find that mid-range field strengths of {approx}40-50 kG produce emerging loops that best match the observed properties of solar active regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997SPD....28.0233H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997SPD....28.0233H"><span>Chromospheric Heating and the Excitation of <span class="hlt">Magnetic</span> <span class="hlt">Tube</span> Waves Through p-Mode Buffeting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hindman, Bradley W.</p> <p>1997-05-01</p> <p>The dissipation of <span class="hlt">magnetic</span> <span class="hlt">tube</span> waves may be the primary source of energy in the thermal balance of the solar chromosphere and corona. In this paper, I compute an upper limit on the energy <span class="hlt">flux</span> of <span class="hlt">tube</span> waves that can be driven into the chromosphere if the waves are excited by buffeting of <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> by p--modes. In addition, I estimate the p--mode line widths which result from this transfer of energy from the modes to the <span class="hlt">flux</span> <span class="hlt">tube</span> waves. To obtain the upper limit, I assume that the solar <span class="hlt">magnetic</span> field has a fibril structure consisting of a large set of well--separated, identical <span class="hlt">tubes</span>. Each <span class="hlt">tube</span> is axisymmetric, vertical and slender. I approximate the solar atmosphere with a truncated isentropic polytrope, chosen such that it's upper surface matches the tau_ {5000}=1 layer of the photospheric model of Maltby (1986). The response of the fibrils is described using the thin <span class="hlt">flux</span> <span class="hlt">tube</span> approximation, ignoring multiple scattering between the <span class="hlt">tubes</span>, and assuming that the p--modes force the <span class="hlt">tubes</span> incoherently. The effects of the region above the surface of the polytrope, where a flaring <span class="hlt">flux</span> <span class="hlt">tube</span> is poorly represented by the thin <span class="hlt">flux</span> equations, are simulated through a boundary condition applied at the polytrope's surface. By varying this boundary condition the influence of any upper atmosphere can be reproduced. To compute an upper limit, I chose the boundary condition which optimizes the upward <span class="hlt">flux</span> of waves. I find that the largest <span class="hlt">flux</span> of <span class="hlt">tube</span> waves that can be sent into chromosphere is 29 ergs cm(-2) s(-1) for a fibril field with a 1% filling factor. This <span class="hlt">flux</span> is miniscule when compared to the energy <span class="hlt">flux</span> necessary to heat the chromosphere or corona. Therefore, <span class="hlt">tube</span> waves generated by the buffeting of <span class="hlt">magnetic</span> fibrils by acoustic waves are inconsequential in the energy balance of the upper atmosphere. Furthermore, using the same boundary conditions, I find that the line width of a p--mode due to the absorption of that mode by the fibrils can be a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5399402','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5399402"><span>Interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span>: Measurement and balance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McComas, D.J.; Gosling, J.T.; Phillips, J.L. )</p> <p>1992-01-01</p> <p>The authors have developed a new method for determining the approximate <span class="hlt">magnetic</span> <span class="hlt">flux</span> content of the various solar wind structures in the ecliptic plane, using single-spacecraft measurements. The two-dimensional <span class="hlt">magnetic</span> <span class="hlt">flux</span> in a region of the solar wind is given by the integral of the radial <span class="hlt">magnetic</span> field component over an arc perpendicular to the radial. Unfortunately, such measurements cannot be achieved with single (or even several) spacecraft in the solar wind. They will show that the desired two-dimensional, ecliptic plane <span class="hlt">magnetic</span> <span class="hlt">flux</span> integral, at least for regions with simple <span class="hlt">magnetic</span> topologies, is equivalent to {phi} = {integral} B{sub y}{vert bar}v{vert bar}dt, where B{sub y} is the ecliptic plane field component perpendicular to the solar wind velocity vector v. Thus {phi} can be determined entirely from measured quantities. In this study they examine variations in the <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the ecliptic plane over a 16-year interval. In addition, they address the question of the opening and closing of interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> by comparing the ecliptic plane <span class="hlt">flux</span> content of both coronal mass ejections (CMEs) and heat <span class="hlt">flux</span> droplets (HFDs). If CMEs remain at least partially attached to the Sun, they would serve to open new <span class="hlt">magnetic</span> <span class="hlt">flux</span> to the interplanetary medium. In contrast, <span class="hlt">flux</span> could be closed off by reconnection across helmet streamers in the corona, leading to the release of U-shaped <span class="hlt">magnetic</span> structures open to the outer heliosphere at both ends and to the return of closed arches to the Sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IAUGA..2302313M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IAUGA..2302313M"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Cancellation and Formation of Prominence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miley, George; Kim, Mun Song; Chon Nam, Sok; Kim, Kyong Chol</p> <p>2015-08-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> cancellation appears to be closely related to various kinds of solar activities such as flares, microflares/surges/jets, X-ray bright points, erupting mini-filaments, transition region explosive events, filament formation, filament activation and eruption, and coronal mass ejections. It is commonly believed that <span class="hlt">magnetic</span> reconnections in the low atmosphere are responsible for canceling <span class="hlt">magnetic</span> features, and <span class="hlt">magnetic</span> fragments are observed to originate as bipoles. According to the Sweet-Parker type reconnection model, the inflow speed closely corresponds to the converging speed of each pole in a canceling <span class="hlt">magnetic</span> feature and the rate of <span class="hlt">flux</span> cancellation must be explained by the observed converging speed. As distinct from the corona, the efficiency of photospheric <span class="hlt">magnetic</span> reconnection may be due to the small Cowling conductivity, instead of the Spitzer, of weakly ionized and <span class="hlt">magnetized</span> plasma in the low atmosphere of the sun. Using the VAL-C atmospheric model and Cowling conductivity, we have computed the parameters describing Sweet-Parker type reconnecting current sheets in the plasma of the solar photosphere and chromosphere, and particularly for the phenomena of <span class="hlt">magnetic</span> <span class="hlt">flux</span> cancellation and dark filament formation which occurred on July 2, 1994 we have estimated the rate of <span class="hlt">flux</span> cancellation, the inflow speed(the converging speed) and the upward mass <span class="hlt">flux</span> to compare with the observation. The results show that when taking account of the Cowling conductivity in the low atmosphere, large <span class="hlt">flux</span> cancellation rates(></u>1019Mxhr-1) in solar active regions are better explained than by the Spitzer conductivity-considered reconnection model. Particularly for the <span class="hlt">flux</span> cancellation event on July 2, 1994, the inflow speed(0.26kms-1)is almost similar to the converging speed(0.22kms-1)and the upward mass <span class="hlt">flux</span>(3.3X1012gs-1) in the model is sufficient for the large dark filament formation in a time of several hours through <span class="hlt">magnetic</span> <span class="hlt">flux</span> cancellation process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21452684','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21452684"><span>AN ESTIMATE OF THE DETECTABILITY OF RISING <span class="hlt">FLUX</span> <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Birch, A. C.; Braun, D. C.; Fan, Y.</p> <p>2010-11-10</p> <p>The physics of the formation of <span class="hlt">magnetic</span> active regions (ARs) is one of the most important problems in solar physics. One main class of theories suggests that ARs are the result of <span class="hlt">magnetic</span> <span class="hlt">flux</span> that rises from the tachocline. Time-distance helioseismology, which is based on measurements of wave propagation, promises to allow the study of the subsurface behavior of this <span class="hlt">magnetic</span> <span class="hlt">flux</span>. Here, we use a model for a buoyant <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentration together with the ray approximation to show that the dominant effect on the wave propagation is expected to be from the roughly 100 m s{sup -1} retrograde flow associated with the rising <span class="hlt">flux</span>. Using a B-spline-based method for carrying out inversions of wave travel times for flows in spherical geometry, we show that at 3 days before emergence the detection of this retrograde flow at a depth of 30 Mm should be possible with a signal-to-noise level of about 8 with a sample of 150 emerging ARs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998A%26A...332.1064H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998A%26A...332.1064H"><span>Spectral line radiation from solar small-scale <span class="hlt">flux</span> <span class="hlt">tubes</span>. II</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasan, S. S.; Kneer, F.; Kalkofen, W.</p> <p>1998-04-01</p> <p>We examine spectral line radiation from small-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> in the solar atmosphere. This is a continuation of work by Kneer et al. (1996). The main difference with the previous investigation is in the choice of the external atmosphere. Earlier we adopted an atmosphere resembling the empirical quiet Sun model for the ambient medium. In the present study, we iteratively adjust the temperature structure of the external atmosphere to fit the Stokes I and V profiles and the average continuum intensities with those obtained from observations. Our models are hotter in the uppermost photospheric layers and cooler in the deeper layers than the quiet Sun model and agree well with semi-empirical <span class="hlt">flux</span> <span class="hlt">tube</span> models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SMaS...26e5027D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SMaS...26e5027D"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> biasing of magnetostrictive sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deng, Zhangxian; Dapino, Marcelo J.</p> <p>2017-05-01</p> <p>The performance of magnetostrictive materials, especially those with high initial <span class="hlt">magnetic</span> permeability and associated low <span class="hlt">magnetic</span> reluctance, is sensitive to not just the amount of <span class="hlt">magnetic</span> bias but also how the bias is applied. Terfenol-D and Galfenol have been characterized under constant <span class="hlt">magnetic</span> field and constant magnetomotive force, which require active control. The application of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> bias utilizing permanent <span class="hlt">magnets</span> allows for robust magnetostrictive systems that require no active control. However, this biasing configuration has not been thoroughly investigated. This study presents <span class="hlt">flux</span> density versus stress major loops of Terfenol-D and Galfenol at various <span class="hlt">magnetic</span> <span class="hlt">flux</span> biases. A new piezomagnetic coefficient {d}33φ is defined as the locally-averaged slope of <span class="hlt">flux</span> density versus stress. Considering the materials alone, the maximum {d}33φ is 18.42 T GPa-1 and 19.53 T GPa-1 for Terfenol-D and Galfenol, respectively. Compared with the peak piezomagnetic coefficient {d}33* measured under controlled <span class="hlt">magnetic</span> fields, the piezomagnetic coefficient {d}33φ is 26% and 74% smaller for Terfenol-D and Galfenol, respectively. This study shows that adding parallel <span class="hlt">magnetic</span> <span class="hlt">flux</span> paths to low-reluctance magnetostrictive components can partially compensate for the performance loss. With a low carbon steel <span class="hlt">flux</span> path in parallel to the Galfenol specimen, the maximum {d}33φ increased to 28.33 T GPa-1 corresponding to a 45% improvement compared with the case without a <span class="hlt">flux</span> path. Due to its low <span class="hlt">magnetic</span> permeability, Terfenol-D does not benefit from the addition of a parallel <span class="hlt">flux</span> path.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Ap%26SS.361..355A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Ap%26SS.361..355A"><span>Particle acceleration in three-dimensional reconnection of <span class="hlt">flux-tube</span> disconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akbari, Z.; Hosseinpour, M.; Mohammadi, M. A.</p> <p>2016-11-01</p> <p>"<span class="hlt">Flux-tube</span> disconnection" is a type of steady-state three-dimensional <span class="hlt">magnetic</span> reconnection with O-point at the origin of the resistive diffusion region. <span class="hlt">Magnetic</span> reconnection is accepted as a potential mechanism for particle acceleration in astrophysical and space plasmas, especially in solar flares. By using the static <span class="hlt">magnetic</span> and electric fields for <span class="hlt">flux-tube</span> disconnection, features of test particle acceleration with input parameters for the solar corona are investigated. We show that a proton injected close to origin of the diffusion region can be accelerated to a very high kinetic energy along the <span class="hlt">magnetic</span> field lines. The efficient acceleration takes place at the radial point where the electric drift velocity has its maximum magnitude. However, a proton injected at radial distances far away from the origin is not accelerated efficiently and even may be trapped in the field lines. The final kinetic energy of the particle depends significantly on the amplitude of the electric field rather than the amplitude of <span class="hlt">magnetic</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..DPPCP9142L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..DPPCP9142L"><span>Building 3D data sets of <span class="hlt">flux</span> <span class="hlt">tube</span> dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loseth, B.; Intrator, T. P.; Sears, J.</p> <p>2010-11-01</p> <p><span class="hlt">Magnetic</span> Reconnection occurs when oppositely directed <span class="hlt">magnetic</span> fields are advected towards each other as plasma flow. The <span class="hlt">magnetic</span> fields diffuse through a small region where the frozen <span class="hlt">flux</span> condition of ideal magnetohydrodynamics (MHD) breaks down and the field lines lose their identity and reconnect to other fields. The reconnection process is important in the confinement of fusion plasmas as well as long-standing solar-physics issues in solar flares, geomagnetic storms, and black hole accretion discs. The Reconnection Scaling Experiment (RSX) uses plasma guns to create one, two, or more parallel <span class="hlt">flux</span> ropes in a cylindrical chamber with an axial <span class="hlt">magnetic</span> guide field. The plasma channels twist helically and merge or bounce depending on the attractive force due to the parallel currents and the repulsive force associated with axial and azimuthal <span class="hlt">magnetic</span> field line bending. The dynamics of merging and bouncing may lead to a new understanding of the statistical mechanics of <span class="hlt">magnetic</span> fields and provide a means of visualizing three-dimensional MHD turbulence. An update of the RSX vessel including an adjustable <span class="hlt">magnetic</span> probe array is currently under way and will allow for the building of 3D data sets of these dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MNRAS.460.3488S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MNRAS.460.3488S"><span>Strongly <span class="hlt">magnetized</span> accretion discs require poloidal <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.</p> <p>2016-08-01</p> <p>Motivated by indirect observational evidence for strongly <span class="hlt">magnetized</span> accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong <span class="hlt">magnetization</span> state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal <span class="hlt">magnetic</span> field of equipartition strength. We demonstrate that discs with zero net vertical <span class="hlt">magnetic</span> <span class="hlt">flux</span> and realistic boundary conditions cannot sustain a strong toroidal field. However, a <span class="hlt">magnetic</span> pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical <span class="hlt">flux</span> and realistic boundary conditions. Our results suggest that poloidal <span class="hlt">flux</span> is a necessary prerequisite for the sustainability of strongly <span class="hlt">magnetized</span> accretion discs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...827....7K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...827....7K"><span>Chromospheric and Coronal Wave Generation in a <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Sheath</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kato, Yoshiaki; Steiner, Oskar; Hansteen, Viggo; Gudiksen, Boris; Wedemeyer, Sven; Carlsson, Mats</p> <p>2016-08-01</p> <p>Using radiation magnetohydrodynamic simulations of the solar atmospheric layers from the upper convection zone to the lower corona, we investigate the self-consistent excitation of slow magneto-acoustic body waves (slow modes) in a <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentration. We find that the convective downdrafts in the close surroundings of a two-dimensional <span class="hlt">flux</span> slab “pump” the plasma inside it in the downward direction. This action produces a downflow inside the <span class="hlt">flux</span> slab, which encompasses ever higher layers, causing an upwardly propagating rarefaction wave. The slow mode, excited by the adiabatic compression of the downflow near the optical surface, travels along the <span class="hlt">magnetic</span> field in the upward direction at the <span class="hlt">tube</span> speed. It develops into a shock wave at chromospheric heights, where it dissipates, lifts the transition region, and produces an offspring in the form of a compressive wave that propagates further into the corona. In the wake of downflows and propagating shock waves, the atmosphere inside the <span class="hlt">flux</span> slab in the chromosphere and higher tends to oscillate with a period of ν ≈ 4 mHz. We conclude that this process of “<span class="hlt">magnetic</span> pumping” is a most plausible mechanism for the direct generation of longitudinal chromospheric and coronal compressive waves within <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations, and it may provide an important heat source in the chromosphere. It may also be responsible for certain types of dynamic fibrils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22364580','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22364580"><span>GENERATION OF MAGNETOHYDRODYNAMIC WAVES IN LOW SOLAR ATMOSPHERIC <span class="hlt">FLUX</span> <span class="hlt">TUBES</span> BY PHOTOSPHERIC MOTIONS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mumford, S. J.; Fedun, V.; Erdélyi, R.</p> <p>2015-01-20</p> <p>Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> are generated via the interaction of granulation motion and the background <span class="hlt">magnetic</span> field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy <span class="hlt">flux</span>. The wave energy <span class="hlt">flux</span> distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total <span class="hlt">flux</span>) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon <span class="hlt">flux</span> surface radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...799....6M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...799....6M"><span>Generation of Magnetohydrodynamic Waves in Low Solar Atmospheric <span class="hlt">Flux</span> <span class="hlt">Tubes</span> by Photospheric Motions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mumford, S. J.; Fedun, V.; Erdélyi, R.</p> <p>2015-01-01</p> <p>Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions, small-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> are generated via the interaction of granulation motion and the background <span class="hlt">magnetic</span> field. This paper studies the effects of these motions on magnetohydrodynamic (MHD) wave excitation from broadband photospheric drivers. Numerical experiments of linear MHD wave propagation in a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> embedded in a realistic gravitationally stratified solar atmosphere between the photosphere and the low choromosphere (above β = 1) are performed. Horizontal and vertical velocity field drivers mimic granular buffeting and solar global oscillations. A uniform torsional driver as well as Archimedean and logarithmic spiral drivers mimic observed torsional motions in the solar photosphere. The results are analyzed using a novel method for extracting the parallel, perpendicular, and azimuthal components of the perturbations, which caters to both the linear and non-linear cases. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of excited modes via velocity perturbations and wave energy <span class="hlt">flux</span>. The wave energy <span class="hlt">flux</span> distribution is calculated to enable the quantification of the relative strengths of excited modes. The torsional drivers primarily excite Alfvén modes (≈60% of the total <span class="hlt">flux</span>) with small contributions from the slow kink mode, and, for the logarithmic spiral driver, small amounts of slow sausage mode. The horizontal and vertical drivers primarily excite slow kink or fast sausage modes, respectively, with small variations dependent upon <span class="hlt">flux</span> surface radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910031440&hterms=projectile&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dprojectile','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910031440&hterms=projectile&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dprojectile"><span><span class="hlt">Magnetic</span> detector for projectiles in <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogdanoff, D. W.; Knowlen, C.; Murakami, D.; Stonich, I.</p> <p>1990-01-01</p> <p>A new wall-mounted, <span class="hlt">magnetic</span> detector is presented for measuring projectile passage times in <span class="hlt">tubes</span>. The detector has the advantages of simplicity over laser and microwave techniques and has other advantages over the electrical contact wire technique. Representative data are presented. The detector is shown to be very insensitive to strong pressure waves and combustion, but able to detect the passage of the projectile (carrying one or two <span class="hlt">magnets</span>) clearly. Two modes of operation of the detector are described and the use of these detectors to measure projectile velocities, accelerations, and spin rates is discussed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910031440&hterms=magnetic+walls&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmagnetic%2Bwalls','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910031440&hterms=magnetic+walls&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dmagnetic%2Bwalls"><span><span class="hlt">Magnetic</span> detector for projectiles in <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogdanoff, D. W.; Knowlen, C.; Murakami, D.; Stonich, I.</p> <p>1990-01-01</p> <p>A new wall-mounted, <span class="hlt">magnetic</span> detector is presented for measuring projectile passage times in <span class="hlt">tubes</span>. The detector has the advantages of simplicity over laser and microwave techniques and has other advantages over the electrical contact wire technique. Representative data are presented. The detector is shown to be very insensitive to strong pressure waves and combustion, but able to detect the passage of the projectile (carrying one or two <span class="hlt">magnets</span>) clearly. Two modes of operation of the detector are described and the use of these detectors to measure projectile velocities, accelerations, and spin rates is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/117789','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/117789"><span>Maximum allowable heat <span class="hlt">flux</span> for a submerged horizontal <span class="hlt">tube</span> bundle</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McEligot, D.M.</p> <p>1995-08-14</p> <p>For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or {open_quotes}critical{close_quotes}) heat <span class="hlt">flux</span> is studied for unconfined <span class="hlt">tube</span> bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820037568&hterms=twist+drive&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtwist%2Bdrive','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820037568&hterms=twist+drive&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtwist%2Bdrive"><span>Alfven waves in the solar atmosphere. III - Nonlinear waves on open <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hollweg, J. V.; Jackson, S.; Galloway, D.</p> <p>1982-01-01</p> <p>Consideration is given the nonlinear propagation of Alfven waves on solar <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>, where the <span class="hlt">tubes</span> are taken to be vertical, axisymmetric and initially untwisted and the Alfven waves are time-dependent axisymmetric twists. The propagation of the waves into the chromosphere and corona is investigated through the numerical solution of a set of nonlinear, time-dependent equations coupling the Alfven waves into motions that are parallel to the initial <span class="hlt">magnetic</span> field. It is concluded that Alfven waves can steepen into fast shocks in the chromosphere, pass through the transition region to produce high-velocity pulses, and then enter the corona, which they heat. The transition region pulses have amplitudes of about 60 km/sec, and durations of a few tens of seconds. In addition, the Alfven waves exhibit a tendency to drive upward flows, with many of the properties of spicules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21316596','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21316596"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span>, Wilson line, and orbifold</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Abe, Hiroyuki; Choi, Kang-Sin; Kobayashi, Tatsuo; Ohki, Hiroshi</p> <p>2009-12-15</p> <p>We study torus/orbifold models with <span class="hlt">magnetic</span> <span class="hlt">flux</span> and Wilson line backgrounds. The number of zero modes and their profiles depend on those backgrounds. That has interesting implications from the viewpoint of particle phenomenology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22121858','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22121858"><span><span class="hlt">FLUX</span> EMERGENCE IN A <span class="hlt">MAGNETIZED</span> CONVECTION ZONE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pinto, R. F.; Brun, A. S.</p> <p>2013-07-20</p> <p>We study the influence of a dynamo <span class="hlt">magnetic</span> field on the buoyant rise and emergence of twisted <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes and their influence on the global external <span class="hlt">magnetic</span> field. We ran three-dimensional MHD numerical simulations using the ASH code (anelastic spherical harmonics) and analyzed the dynamical evolution of such buoyant <span class="hlt">flux</span> ropes from the bottom of the convection zone until the post-emergence phases. The global nature of this model can only very crudely and inaccurately represent the local dynamics of the buoyant rise of the implanted <span class="hlt">magnetic</span> structure, but nonetheless allows us to study the influence of global effects, such as self-consistently generated differential rotation and meridional circulation, and of Coriolis forces. Although motivated by the solar context, this model cannot be thought of as a realistic model of the rise of <span class="hlt">magnetic</span> structures and their emergence in the Sun, where the local dynamics are completely different. The properties of initial phases of the buoyant rise are determined essentially by the <span class="hlt">flux</span>-rope's properties and the convective flows and consequently are in good agreement with previous studies. However, the effects of the interaction of the background dynamo field become increasingly strong as the <span class="hlt">flux</span> ropes evolve. During the buoyant rise across the convection zone, the <span class="hlt">flux</span>-rope's <span class="hlt">magnetic</span> field strength scales as B{proportional_to}{rho}{sup {alpha}}, with {alpha} {approx}< 1. An increase of radial velocity, density, and current density is observed to precede <span class="hlt">flux</span> emergence at all longitudes. The geometry, latitude, and relative orientation of the <span class="hlt">flux</span> ropes with respect to the background <span class="hlt">magnetic</span> field influences the resulting rise speeds, zonal flow amplitudes (which develop within the <span class="hlt">flux</span> ropes), and the corresponding surface signatures. This influences the morphology, duration and amplitude of the surface shearing, and the Poynting <span class="hlt">flux</span> associated with <span class="hlt">magnetic</span> <span class="hlt">flux</span>-rope emergence. The emerged <span class="hlt">magnetic</span> <span class="hlt">flux</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Icar..226..186S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Icar..226..186S"><span>Auroral electron precipitation and <span class="hlt">flux</span> <span class="hlt">tube</span> erosion in Titan’s upper atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Snowden, D.; Yelle, R. V.; Galand, M.; Coates, A. J.; Wellbrock, A.; Jones, G. H.; Lavvas, P.</p> <p>2013-09-01</p> <p>Cassini dasta shows that Titan’s atmosphere strongly depletes the electron content in Saturn’s <span class="hlt">flux</span> <span class="hlt">tubes</span>, producing features known as electron bite-outs, which indicate that the <span class="hlt">flux</span> of auroral electrons decreases over time. To understand this process we have developed a time-dependent two-stream model, which uses field line geometries and drift paths calculated by a three-dimensional multi-fluid model of Titan’s plasma interaction. The boundary conditions of the model account for the time-dependent reduction or increase in electron <span class="hlt">flux</span> along Saturn’s <span class="hlt">magnetic</span> field lines because of the loss or production of electrons in Titan’s atmosphere. The modification of the auroral electron <span class="hlt">flux</span> depends on the electron bounce period in Saturn’s outer magnetosphere; therefore, we also calculate electron bounce periods along several Kronian field lines accounting for both the <span class="hlt">magnetic</span> mirroring force and the field-aligned electric potential in Saturn’s plasma sheet. We use the time-dependent two-stream model to calculate how the reduction in the auroral electron <span class="hlt">flux</span> affects electron impact ionization and energy deposition rates in Titan’s upper atmosphere. We find that the <span class="hlt">flux</span> of higher energy (>50 eV) electrons entering Titan’s atmosphere is strongly reduced over time, resulting in smaller ionization and energy deposition rates below ∼1300 km altitude. Finally, we show that sample spectrograms produced from our calculations are consistent with CAPS-ELS data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhRvX...2d1007M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhRvX...2d1007M"><span>Dynamic <span class="hlt">Flux</span> <span class="hlt">Tubes</span> Form Reservoirs of Stability in Neuronal Circuits</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Monteforte, Michael; Wolf, Fred</p> <p>2012-10-01</p> <p>Neurons in cerebral cortical circuits interact by sending and receiving electrical impulses called spikes. The ongoing spiking activity of cortical circuits is fundamental to many cognitive functions including sensory processing, working memory, and decision making. London et al. [Sensitivity to Perturbations <emph type="italic">In Vivo</emph> Implies High Noise and Suggests Rate Coding in Cortex, Nature (London)NATUAS0028-0836 466, 123 (2010).10.1038/nature09086] recently argued that even a single additional spike can cause a cascade of extra spikes that rapidly decorrelate the microstate of the network. Here, we show theoretically in a minimal model of cortical neuronal circuits that single-spike perturbations trigger only a very weak rate response. Nevertheless, single-spike perturbations are found to rapidly decorrelate the microstate of the network, although the dynamics is stable with respect to small perturbations. The coexistence of stable and unstable dynamics results from a system of exponentially separating dynamic <span class="hlt">flux</span> <span class="hlt">tubes</span> around stable trajectories in the network’s phase space. The radius of these <span class="hlt">flux</span> <span class="hlt">tubes</span> appears to decrease algebraically with neuron number N and connectivity K, which implies that the entropy of the circuit’s repertoire of state sequences scales as Nln⁡(KN).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920030757&hterms=superconductors+application&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsuperconductors%2Bapplication','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920030757&hterms=superconductors+application&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsuperconductors%2Bapplication"><span><span class="hlt">Magnetic</span> refrigeration using <span class="hlt">flux</span> compression in superconductors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Israelsson, U. E.; Strayer, D. M.; Jackson, H. W.; Petrac, D.</p> <p>1990-01-01</p> <p>The feasibility of using <span class="hlt">flux</span> compression in high-temperature superconductors to produce the large time-varying <span class="hlt">magnetic</span> fields required in a field cycled <span class="hlt">magnetic</span> refrigerator operating between 20 K and 4 K is presently investigated. This paper describes the refrigerator concept and lists limitations and advantages in comparison with conventional refrigeration techniques. The maximum fields obtainable by <span class="hlt">flux</span> compression in high-temperature supercoductor materials, as presently prepared, are too low to serve in such a refrigerator. However, reports exist of critical current values that are near usable levels for <span class="hlt">flux</span> pumps in refrigerator applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvD..95d5005M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvD..95d5005M"><span>Fermionic vacuum polarization by an Abelian <span class="hlt">magnetic</span> <span class="hlt">tube</span> in the cosmic string spacetime</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maior de Sousa, M. S.; Ribeiro, R. F.; Bezerra de Mello, E. R.</p> <p>2017-02-01</p> <p>In this paper, we consider a charged massive fermionic quantum field in the idealized cosmic string spacetime and in the presence of a <span class="hlt">magnetic</span> field confined in a cylindrical <span class="hlt">tube</span> of finite radius. Three distinct configurations for the <span class="hlt">magnetic</span> fields are taken into account: (i) a cylindrical shell of radius a , (ii) a <span class="hlt">magnetic</span> field proportional to 1 /r , and (iii) a constant <span class="hlt">magnetic</span> field. In these three cases, the axis of the infinitely long <span class="hlt">tube</span> of radius a coincides with the cosmic string. Our main objectives in this paper are to analyze the fermionic condensate (FC) and the vacuum expectation value (VEV) of the fermionic energy-momentum tensor. In order to do that, we explicitly construct the complete set of normalized wave functions for each configuration of the <span class="hlt">magnetic</span> field. We show that in the region outside the <span class="hlt">tube</span>, the FC and the VEV of the energy-momentum tensor are decomposed into two parts: The first ones correspond to the zero-thickness <span class="hlt">magnetic</span> <span class="hlt">flux</span> contributions, and the second ones are induced by the nontrivial structure of the <span class="hlt">magnetic</span> field, named core-induced contributions. The latter present specific forms depending on the <span class="hlt">magnetic</span> field configuration considered. We also show that the VEV of the energy-momentum tensor is diagonal and obeys the conservation condition, and its trace is expressed in terms of the fermionic condensate. The zero-thickness contributions to the FC and VEV of the energy-momentum tensor depend only on the fractional part of the ration of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> inside the <span class="hlt">tube</span> by the quantum one. As to the core-induced contributions, they depend on the total <span class="hlt">magnetic</span> <span class="hlt">flux</span> inside the <span class="hlt">tube</span> and, consequently, in general, are not a periodic function of the <span class="hlt">magnetic</span> <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20997101','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20997101"><span>Influence of Test <span class="hlt">Tube</span> Material on Subcooled Flow Boiling Critical Heat <span class="hlt">Flux</span> in Short Vertical <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Koichi Hata; Masahiro Shiotsu; Nobuaki Noda</p> <p>2006-07-01</p> <p>The steady state subcooled flow boiling critical heat <span class="hlt">flux</span> (CHF) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet subcooling ({delta}T{sub sub,in} = 48.6 to 154.7 K), the inlet pressure (P{sub in} = 735.2 to 969.0 kPa) and the increasing heat input (Q{sub 0} exp(t/t), t = 10, 20 and 33.3 s) are systematically measured with the experimental water loop. The 304 Stainless Steel (SUS304) test <span class="hlt">tubes</span> of inner diameters (d = 6 mm), heated lengths (L = 66 mm) and L/d = 11 with the inner surface of rough finished (Surface roughness, R{sub a} = 3.18 {mu}m), the Cupro Nickel (Cu-Ni 30%) test <span class="hlt">tubes</span> of d = 6 mm, L = 60 mm and L/d = 10 with R{sub a} = 0.18 {mu}m and the Platinum (Pt) test <span class="hlt">tubes</span> of d = 3 and 6 mm, L = 66.5 and 69.6 mm, and L/d 22.2 and 11.6 respectively with R{sub a} = 0.45 {mu}m are used in this work. The CHF data for the SUS304, Cu-Ni 30% and Pt test <span class="hlt">tubes</span> were compared with SUS304 ones for the wide ranges of d and L/d previously obtained and the values calculated by the authors' published steady state CHF correlations against outlet and inlet subcooling. The influence of the test <span class="hlt">tube</span> material on CHF is investigated into details and the dominant mechanism of subcooled flow boiling critical heat <span class="hlt">flux</span> is discussed. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22410343','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22410343"><span>Heat <span class="hlt">flux</span> viscosity in collisional <span class="hlt">magnetized</span> plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liu, C.; Fox, W.; Bhattacharjee, A.</p> <p>2015-05-15</p> <p>Momentum transport in collisional <span class="hlt">magnetized</span> plasmas due to gradients in the heat <span class="hlt">flux</span>, a “heat <span class="hlt">flux</span> viscosity,” is demonstrated. Even though no net particle <span class="hlt">flux</span> is associated with a heat <span class="hlt">flux</span>, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-<span class="hlt">flux</span> viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat <span class="hlt">flux</span> can dominate over ordinary plasma flows. The heat <span class="hlt">flux</span> viscosity can influence the dynamics of the <span class="hlt">magnetic</span> field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing <span class="hlt">magnetic</span> field line reconnection. The heat <span class="hlt">flux</span> viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22004408','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22004408"><span>ON THE DISPERSION AND SCATTERING OF MAGNETOHYDRODYNAMIC WAVES BY LONGITUDINALLY STRATIFIED <span class="hlt">FLUX</span> <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Andries, J.; Cally, P. S. E-mail: paul.cally@monash.edu</p> <p>2011-12-20</p> <p>We provide a fairly general analytic theory for the dispersion and scattering of magnetohydrodynamic waves by longitudinally stratified <span class="hlt">flux</span> <span class="hlt">tubes</span>. The theory provides a common framework for, and synthesis of, many previous studies of <span class="hlt">flux</span> <span class="hlt">tube</span> oscillations that were carried out under various simplifying assumptions. The present theory focuses on making only a minimal number of assumptions. As a result it thus provides an analytical treatment of several generalizations of existing <span class="hlt">tube</span> oscillation models. The most important practical cases are inclusion of plasma pressure and possibly buoyancy effects in models of straight non-diverging <span class="hlt">tubes</span> as applied in coronal seismology, and relaxation of the 'thin <span class="hlt">tube</span>' approximation in oscillation models of diverging <span class="hlt">tubes</span> as applied both in the context of p-mode scattering and coronal seismology. In particular, it illustrates the unifying theoretical framework underlying both the description of waves scattered by <span class="hlt">flux</span> <span class="hlt">tubes</span> and the dispersion of waves carried along <span class="hlt">flux</span> <span class="hlt">tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900000331&hterms=magnetic+hall+sensor&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagnetic%2Bhall%2Bsensor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900000331&hterms=magnetic+hall+sensor&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmagnetic%2Bhall%2Bsensor"><span><span class="hlt">Flux</span>-Feedback <span class="hlt">Magnetic</span>-Suspension Actuator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Groom, Nelson J.</p> <p>1990-01-01</p> <p><span class="hlt">Flux</span>-feedback <span class="hlt">magnetic</span>-suspension actuator provides <span class="hlt">magnetic</span> suspension and control forces having linear transfer characteristics between force command and force output over large range of gaps. Hall-effect devices used as sensors for electronic feedback circuit controlling currents flowing in electromagnetic windings to maintain <span class="hlt">flux</span> linking suspended element at substantially constant value independent of changes in length of gap. Technique provides effective method for maintenance of constant <span class="hlt">flux</span> density in gap and simpler than previous methods. Applications include <span class="hlt">magnetic</span> actuators for control of shapes and figures of antennas and of precise segmented reflectors, <span class="hlt">magnetic</span> suspensions in devices for storage of angular momentum and/or kinetic energy, and systems for control, pointing, and isolation of instruments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870052736&hterms=wave+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwave%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870052736&hterms=wave+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwave%2Benergy"><span>Particle propagation, wave growth and energy dissipation in a flaring <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>White, S. M.; Melrose, D. B.; Dulk, G. A.</p> <p>1986-01-01</p> <p>Wave amplification by downgoing particles in a common flare model is investigated. The flare is assumed to occur at the top of a coronal <span class="hlt">magnetic</span> <span class="hlt">flux</span> loop, and results in the heating of plasma in the flaring region. The hot electrons propagate down the legs of the <span class="hlt">flux</span> <span class="hlt">tube</span> towards increasing <span class="hlt">magnetic</span> field. It is simple to demonstrate that the velocity distributions which result in this model are unstable to both beam instabilities and cyclotron maser action. An explanation is presented for the propagation effects on the distribution, and the properties of the resulting amplified waves are explored, concentrating on cyclotron maser action, which has properties (emission in the z mode below the local gyrofrequency) quite different from maser action by other distributions considered in the context of solar flares. The z mode waves will be damped in the coronal plasma surrounding the flaring <span class="hlt">flux</span> <span class="hlt">tube</span> and lead to heating there. This process may be important in the overall energy budget of the flare. The downgoing maser is compared with the loss cone maser, which is more likely to produce observable bursts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SoPh..289.1193W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SoPh..289.1193W"><span>Linear MHD Wave Propagation in Time-Dependent <span class="hlt">Flux</span> <span class="hlt">Tube</span>. II. Finite Plasma Beta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williamson, A.; Erdélyi, R.</p> <p>2014-04-01</p> <p>The propagation of magnetohydrodynamic (MHD) waves is an area that has been thoroughly studied for idealised static and steady state magnetised plasma systems applied to numerous solar structures. By applying the generalisation of a temporally varying background density to an open <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span>, mimicking the observed slow evolution of such waveguides in the solar atmosphere, further investigations into the propagation of both fast and slow MHD waves can take place. The assumption of a zero-beta plasma (no gas pressure) was applied in Williamson and Erdélyi ( Solar Phys. 2013, doi:10.1007/s11207-013-0366-9, Paper I) is now relaxed for further analysis here. Firstly, the introduction of a finite thermal pressure to the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> equilibrium modifies the existence of fast MHD waves which are directly comparable to their counterparts found in Paper I. Further, as a direct consequence of the non-zero kinetic plasma pressure, a slow MHD wave now exists, and is investigated. Analysis of the slow wave shows that, similar to the fast MHD wave, wave amplitude amplification takes place in time and height. The evolution of the wave amplitude is determined here analytically. We conclude that for a temporally slowly decreasing background density both propagating magnetosonic wave modes are amplified for over-dense <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span>. This information can be very practical and useful for future solar magneto-seismology applications in the study of the amplitude and frequency properties of MHD waveguides, e.g. for diagnostic purposes, present in the solar atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017A%26A...604A..76M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017A%26A...604A..76M"><span><span class="hlt">Flux</span> rope, hyperbolic <span class="hlt">flux</span> <span class="hlt">tube</span>, and late extreme ultraviolet phases in a non-eruptive circular-ribbon flare</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masson, Sophie; Pariat, Étienne; Valori, Gherardo; Deng, Na; Liu, Chang; Wang, Haimin; Reid, Hamish</p> <p>2017-08-01</p> <p>Context. The dynamics of ultraviolet (UV) emissions during solar flares provides constraints on the physical mechanisms involved in the trigger and the evolution of flares. In particular it provides some information on the location of the reconnection sites and the associated <span class="hlt">magnetic</span> <span class="hlt">fluxes</span>. In this respect, confined flares are far less understood than eruptive flares generating coronal mass ejections. Aims: We present a detailed study of a confined circular flare dynamics associated with three UV late phases in order to understand more precisely which topological elements are present and how they constrain the dynamics of the flare. Methods: We perform a non-linear force-free field extrapolation of the confined flare observed with the Helioseismic and <span class="hlt">Magnetic</span> Imager (HMI) and Atmospheric Imaging Assembly (AIA) instruments on board Solar Dynamics Observatory (SDO). From the 3D <span class="hlt">magnetic</span> field we compute the squashing factor and we analyse its distribution. Conjointly, we analyse the AIA extreme ultraviolet (EUV) light curves and images in order to identify the post-flare loops, and their temporal and thermal evolution. By combining the two analyses we are able to propose a detailed scenario that explains the dynamics of the flare. Results: Our topological analysis shows that in addition to a null-point topology with the fan separatrix, the spine lines and its surrounding quasi-separatix layer (QSL) halo (typical for a circular flare), a <span class="hlt">flux</span> rope and its hyperbolic <span class="hlt">flux</span> <span class="hlt">tube</span> (HFT) are enclosed below the null. By comparing the <span class="hlt">magnetic</span> field topology and the EUV post-flare loops we obtain an almost perfect match between the footpoints of the separatrices and the EUV 1600 Å ribbons and between the HFT field line footpoints and bright spots observed inside the circular ribbons. We show, for the first time in a confined flare, that <span class="hlt">magnetic</span> reconnection occurred initially at the HFT below the <span class="hlt">flux</span> rope. Reconnection at the null point between the <span class="hlt">flux</span> rope and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2444P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2444P"><span><span class="hlt">Magnetic</span> topology of emerging <span class="hlt">flux</span> regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pariat, Etienne</p> <p></p> <p>Coronal <span class="hlt">magnetic</span> fields structure and governs the dynamics of the solar atmosphere. These <span class="hlt">magnetic</span> fields are often complex, composed of multiples domains of <span class="hlt">magnetic</span>-field-lines connectivity. The topology of the <span class="hlt">magnetic</span> field allows a synthetic description of these complex <span class="hlt">magnetic</span> field by highlighting the structural elements that are important for the dynamic and the activity of the corona. Topology identifies the key elements where <span class="hlt">magnetic</span> reconnection will preferentially occurs, and allows to explain and predict the evolution of the coronal plasma. However the topological elements - such as null points, separatrices, separators - do not appear out of thin air. Along with energy, and helicity, the <span class="hlt">magnetic</span> topology of an active region is build up as the consequence of <span class="hlt">flux</span> emergence. Some topological elements, such as bald-patches, are even fully part of the mechanism of <span class="hlt">flux</span> emergence mechanism and drive the evolution and the structuration of the coronal <span class="hlt">magnetic</span> field as it crosses the lower layer of the solar atmosphere. In the present talk I will therefore review our current understanding of the formation of active region in terms of <span class="hlt">magnetic</span> topology. I will speak on how the topological structures which are key to solar activity are formed. Meanwhile I'll also discus the topological properties of emerging active region and how topology influences the very process of <span class="hlt">flux</span> emergence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20705368','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20705368"><span>Dynamics of monopoles and <span class="hlt">flux</span> <span class="hlt">tubes</span> in two-flavor dynamical QCD</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bornyakov, V.G.; Ichie, H.; Koma, Y.; Mori, Y.; Nakamura, Y.; Suzuki, T.; Pleiter, D.; Schierholz, G.; Streuer, T.; Stueben, H.</p> <p>2004-10-01</p> <p>We investigate the confining properties of the QCD vacuum with N{sub f}=2 flavors of dynamical quarks, and compare the results with the properties of the quenched theory. We use nonperturbatively O(a) improved Wilson fermions to keep cutoff effects small. We focus on color <span class="hlt">magnetic</span> monopoles. Among the quantities we study are the monopole density and the monopole screening length, the static potential and the profile of the color electric <span class="hlt">flux</span> <span class="hlt">tube</span>. We furthermore derive the low-energy effective monopole action. Marked differences between the quenched and dynamical vacuum are found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...831...94S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...831...94S"><span>Numerical Simulations of Plasma Dynamics in the Vicinity of a Retracting <span class="hlt">Flux</span> <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, Roger B.; Longcope, Dana W.; McKenzie, David E.</p> <p>2016-11-01</p> <p>In a previous paper, we presented an analytical, zero-β model for supra-arcade downflows in which a retracting <span class="hlt">flux</span> <span class="hlt">tube</span> deforms the surrounding <span class="hlt">magnetic</span> field, constricting the flow of plasma along affected field lines and, in some cases, forcing the plasma to exhibit collimated shocks. Here we present a numerical simulation based on the same model construction—a retracting <span class="hlt">flux</span> <span class="hlt">tube</span> is treated as a rigid boundary around which the plasma is forced to flow and the <span class="hlt">magnetic</span> field and plasma evolve according to the governing equations of magnetohydrodynamics. We find that the collimated shocks described in our previous study are recovered for plasma β in the range of 0 ≤ β ≲ 1, while for 1 ≲ β the behavior is similar to the simpler hydrodynamic case, with classical bow shocks forming when the acoustic Mach number approaches or exceeds unity. Furthermore, we find that while the plasma β is important for identifying the various types of behaviors, more important still is the Alfvén Mach number, which, if large, implies that the bulk kinetic energy of the fluid exceeds the internal energy of the <span class="hlt">magnetic</span> field, thereby leading to the formation of unconfined, fast-mode magnetosonic shocks, even in the limit of small β.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DPPPP8068T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DPPPP8068T"><span>The 3D Structure of <span class="hlt">Flux</span> <span class="hlt">Tubes</span> That Admit Flute Instability in the Scrape-Off-Layer (SOL) of Tokamaks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, Hironori</p> <p>2014-10-01</p> <p>A severe reduction in size down to an ion gyro-radius scale, commonly known as ``squeezing,'' in a lateral dimension of the cross section of a <span class="hlt">flux</span> <span class="hlt">tube</span> is traditionally thought to inhibit the occurrence of the flute instability in the Scrape-off-Layer of a diverted tokamak by isolating the main volume of the <span class="hlt">flux</span> <span class="hlt">tube</span> from its ends at electrically conducting target plates. A study reported here in the 3D <span class="hlt">flux</span> <span class="hlt">tube</span> structure reveals the absence of squeezing for a <span class="hlt">flux</span> <span class="hlt">tube</span> that is sufficiently large in its toroidal extent (small toroidal harmonic number n) and located in a layer of low field-line shear around the ``sweet spot'' (about mid-way between the primary and secondary separatrices). The low-shear layer does not hence inhibit the flute instability through the squeezing mechanism, and may thus restore the flute instability, among the most virulent in the <span class="hlt">magnetized</span> plasma, to the ranks of candidate electrostatic instabilities thought to underlie the turbulence in the SOL in tokamaks. Variations along the <span class="hlt">flux</span> <span class="hlt">tube</span> of geometrical characteristics including the cross section will be calculated to develop criteria for the absence of squeezing. Supported in part by the US DOE under DE-AC02-09CH11466.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22408102','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22408102"><span><span class="hlt">Flux</span> <span class="hlt">tube</span> train model for local turbulence simulation of toroidal plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Watanabe, T.-H.; Sugama, H.; Ishizawa, A.; Nunami, M.</p> <p>2015-02-15</p> <p>A new simulation method for local turbulence in toroidal plasmas is developed by extending the conventional idea of the <span class="hlt">flux</span> <span class="hlt">tube</span> model. In the new approach, a train of <span class="hlt">flux</span> <span class="hlt">tubes</span> is employed, where <span class="hlt">flux</span> <span class="hlt">tube</span> simulation boxes are serially connected at each end along a field line so as to preserve a symmetry of the local gyrokinetic equations for image modes in an axisymmetric torus. Validity of the <span class="hlt">flux</span> <span class="hlt">tube</span> train model is confirmed against the toroidal ion temperature gradient turbulence for a case with a long parallel correlation of fluctuations, demonstrating numerical advantages over the conventional method in the time step size and the symmetry-preserving property.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770052284&hterms=Emergence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEmergence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770052284&hterms=Emergence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DEmergence"><span>Solar cycle variation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, J. M.; Golub, L.; Kreiger, A. S.</p> <p>1977-01-01</p> <p>The number of X-ray bright points (XBP) has been measured from solar X-ray images obtained during two rocket flights in 1976. When compared with the data obtained during the Skylab mission (1973), the number is found to be higher by a factor of 2. As the probability of obtaining the result by chance is less than 1 in 5 million, it is concluded that the number of XBP has increased in the three year interval. As all other indicators of activity have decreased between 1973 and 1976, the cyclical variation of the short-lifetime end of the <span class="hlt">magnetic-flux</span>-emergence spectrum is out of phase with the solar cycle as defined by active regions or sunspots. Since XBP in 1973 contributed more to the emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> than did active regions, the possibility exists that the total amount of emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> may be maximized at a sunspot minimum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT.........5T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT.........5T"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> reconstruction methods for shaped tokamaks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsui, Chi-Wa</p> <p>1993-12-01</p> <p>The use of a variational method permits the Grad-Shafranov (GS) equation to be solved by reducing the problem of solving the two dimensional nonlinear partial differential equation to the problem of minimizing a function of several variables. This high speed algorithm approximately solves the GS equation given a parameterization of the plasma boundary and the current profile (p' and FF' functions). The current profile parameters are treated as unknowns. The goal is to reconstruct the internal <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces of a tokamak plasma and the toroidal current density profile from the external <span class="hlt">magnetic</span> measurements. This is a classic problem of inverse equilibrium determination. The current profile parameters can be evaluated by several different matching procedures. Matching of <span class="hlt">magnetic</span> <span class="hlt">flux</span> and field at the probe locations using the Biot-Savart law and <span class="hlt">magnetic</span> Green's function provides a robust method of <span class="hlt">magnetic</span> reconstruction. The matching of poloidal <span class="hlt">magnetic</span> field on the plasma surface provides a unique method of identifying the plasma current profile. However, the power of this method is greatly compromised by the experimental errors of the <span class="hlt">magnetic</span> signals. The Casing principle provides a very fast way to evaluate the plasma contribution to the <span class="hlt">magnetic</span> signals. It has the potential of being a fast matching method. The performance of this method is hindered by the accuracy of the poloidal <span class="hlt">magnetic</span> field computed from the equilibrium solver. A <span class="hlt">flux</span> reconstruction package has been implemented which integrates a vacuum field solver using a filament model for the plasma, a multilayer perception neural network as an interface, and the volume integration of plasma current density using Green's functions as a matching method for the current profile parameters. The <span class="hlt">flux</span> reconstruction package is applied to compare with the ASEQ and EFIT data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22521597','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22521597"><span><span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> SUPPLEMENT TO CORONAL BRIGHT POINTS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong; Madjarska, Maria S.</p> <p>2016-02-10</p> <p>Coronal bright points (BPs) are associated with <span class="hlt">magnetic</span> bipolar features (MBFs) and <span class="hlt">magnetic</span> cancellation. Here we investigate how BP-associated MBFs form and how the consequent <span class="hlt">magnetic</span> cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and <span class="hlt">Magnetic</span> Imager to investigate the photospheric <span class="hlt">magnetic</span> <span class="hlt">flux</span> evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the <span class="hlt">magnetic</span> <span class="hlt">fluxes</span>. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, <span class="hlt">flux</span> emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the <span class="hlt">flux</span> emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While <span class="hlt">magnetic</span> cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak <span class="hlt">magnetic</span> features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the <span class="hlt">magnetic</span> activities responsible for the BP heating may involve small weak fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...818....9M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...818....9M"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Supplement to Coronal Bright Points</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Madjarska, Maria S.; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong</p> <p>2016-02-01</p> <p>Coronal bright points (BPs) are associated with <span class="hlt">magnetic</span> bipolar features (MBFs) and <span class="hlt">magnetic</span> cancellation. Here we investigate how BP-associated MBFs form and how the consequent <span class="hlt">magnetic</span> cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and <span class="hlt">Magnetic</span> Imager to investigate the photospheric <span class="hlt">magnetic</span> <span class="hlt">flux</span> evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the <span class="hlt">magnetic</span> <span class="hlt">fluxes</span>. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, <span class="hlt">flux</span> emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the <span class="hlt">flux</span> emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While <span class="hlt">magnetic</span> cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak <span class="hlt">magnetic</span> features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the <span class="hlt">magnetic</span> activities responsible for the BP heating may involve small weak fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10117754','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10117754"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> reconstruction methods for shaped tokamaks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tsui, Chi-Wa</p> <p>1993-12-01</p> <p>The use of a variational method permits the Grad-Shafranov (GS) equation to be solved by reducing the problem of solving the 2D non-linear partial differential equation to the problem of minimizing a function of several variables. This high speed algorithm approximately solves the GS equation given a parameterization of the plasma boundary and the current profile (p` and FF` functions). The author treats the current profile parameters as unknowns. The goal is to reconstruct the internal <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces of a tokamak plasma and the toroidal current density profile from the external <span class="hlt">magnetic</span> measurements. This is a classic problem of inverse equilibrium determination. The current profile parameters can be evaluated by several different matching procedures. Matching of <span class="hlt">magnetic</span> <span class="hlt">flux</span> and field at the probe locations using the Biot-Savart law and <span class="hlt">magnetic</span> Green`s function provides a robust method of <span class="hlt">magnetic</span> reconstruction. The matching of poloidal <span class="hlt">magnetic</span> field on the plasma surface provides a unique method of identifying the plasma current profile. However, the power of this method is greatly compromised by the experimental errors of the <span class="hlt">magnetic</span> signals. The Casing Principle provides a very fast way to evaluate the plasma contribution to the <span class="hlt">magnetic</span> signals. It has the potential of being a fast matching method. The performance of this method is hindered by the accuracy of the poloidal <span class="hlt">magnetic</span> field computed from the equilibrium solver. A <span class="hlt">flux</span> reconstruction package has been implemented which integrates a vacuum field solver using a filament model for the plasma, a multi-layer perception neural network as an interface, and the volume integration of plasma current density using Green`s functions as a matching method for the current profile parameters. The <span class="hlt">flux</span> reconstruction package is applied to compare with the ASEQ and EFIT data. The results are promising.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720059605&hterms=thin+film+interference&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dthin%2Bfilm%2Binterference','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720059605&hterms=thin+film+interference&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dthin%2Bfilm%2Binterference"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> penetration into superconducting thin films.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peabody, G. E.; Meservey, R.</p> <p>1972-01-01</p> <p>The quantum-interference technique developed by Meservey (1965) is used to measure directly the absolute value of the penetration depth in lead in tin superconducting thin films. The technique assumes that the change in phase of the superconducting wave function around any contour within the superconductor must be 2 pi n, where n is a nonnegative integer. Results show that the critical current of a superconducting interferometer with two parallel junctions is not strictly periodic in the applied <span class="hlt">magnetic</span> <span class="hlt">flux</span> with a period equal to the <span class="hlt">flux</span> quantum because of the <span class="hlt">magnetic</span> field dependence of the critical currents of the junctions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22525314','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22525314"><span>TIME-DEPENDENT TURBULENT HEATING OF OPEN <span class="hlt">FLUX</span> <span class="hlt">TUBES</span> IN THE CHROMOSPHERE, CORONA, AND SOLAR WIND</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Woolsey, L. N.; Cranmer, S. R.</p> <p>2015-10-01</p> <p>We investigate several key questions of plasma heating in open-field regions of the corona that connect to the solar wind. We present results for a model of Alfvén-wave-driven turbulence for three typical open <span class="hlt">magnetic</span> field structures: a polar coronal hole, an open <span class="hlt">flux</span> <span class="hlt">tube</span> neighboring an equatorial streamer, and an open <span class="hlt">flux</span> <span class="hlt">tube</span> near a strong-field active region. We compare time-steady, one-dimensional turbulent heating models against fully time-dependent three-dimensional reduced-magnetohydrodynamic modeling of BRAID. We find that the time-steady results agree well with time-averaged results from BRAID. The time dependence allows us to investigate the variability of the <span class="hlt">magnetic</span> fluctuations and of the heating in the corona. The high-frequency tail of the power spectrum of fluctuations forms a power law whose exponent varies with height, and we discuss the possible physical explanation for this behavior. The variability in the heating rate is bursty and nanoflare-like in nature, and we analyze the amount of energy lost via dissipative heating in transient events throughout the simulation. The average energy in these events is 10{sup 21.91} erg, within the “picoflare” range, and many events reach classical “nanoflare” energies. We also estimated the multithermal distribution of temperatures that would result from the heating-rate variability, and found good agreement with observed widths of coronal differential emission measure distributions. The results of the modeling presented in this paper provide compelling evidence that turbulent heating in the solar atmosphere by Alfvén waves accelerates the solar wind in open <span class="hlt">flux</span> <span class="hlt">tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...823..110R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...823..110R"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Cancellation in Ellerman Bombs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reid, A.; Mathioudakis, M.; Doyle, J. G.; Scullion, E.; Nelson, C. J.; Henriques, V.; Ray, T.</p> <p>2016-06-01</p> <p>Ellerman Bombs (EBs) are often found to be co-spatial with bipolar photospheric <span class="hlt">magnetic</span> fields. We use Hα imaging spectroscopy along with Fe i 6302.5 Å spectropolarimetry from the Swedish 1 m Solar Telescope (SST), combined with data from the Solar Dynamic Observatory, to study EBs and the evolution of the local <span class="hlt">magnetic</span> fields at EB locations. EBs are found via an EB detection and tracking algorithm. Using NICOLE inversions of the spectropolarimetric data, we find that, on average, (3.43 ± 0.49) × 1024 erg of stored <span class="hlt">magnetic</span> energy disappears from the bipolar region during EB burning. The inversions also show <span class="hlt">flux</span> cancellation rates of 1014-1015 Mx s-1 and temperature enhancements of 200 K at the detection footpoints. We investigate the near-simultaneous flaring of EBs due to co-temporal <span class="hlt">flux</span> emergence from a sunspot, which shows a decrease in transverse velocity when interacting with an existing, stationary area of opposite polarity <span class="hlt">magnetic</span> <span class="hlt">flux</span>, resulting in the formation of the EBs. We also show that these EBs can be fueled further by additional, faster moving, negative <span class="hlt">magnetic</span> <span class="hlt">flux</span> regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120015230','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120015230"><span>Photospheric <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Transport - Supergranules Rule</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, David H.; Rightmire-Upton, Lisa</p> <p>2012-01-01</p> <p>Observations of the transport of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the Sun's photosphere show that active region <span class="hlt">magnetic</span> <span class="hlt">flux</span> is carried far from its origin by a combination of flows. These flows have previously been identified and modeled as separate axisymmetric processes: differential rotation, meridional flow, and supergranule diffusion. Experiments with a surface convective flow model reveal that the true nature of this transport is advection by the non-axisymmetric cellular flows themselves - supergranules. <span class="hlt">Magnetic</span> elements are transported to the boundaries of the cells and then follow the evolving boundaries. The convective flows in supergranules have peak velocities near 500 m/s. These flows completely overpower the superimposed 20 m/s meridional flow and 100 m/s differential rotation. The <span class="hlt">magnetic</span> elements remain pinned at the supergranule boundaries. Experiments with and without the superimposed axisymmetric photospheric flows show that the axisymmetric transport of <span class="hlt">magnetic</span> <span class="hlt">flux</span> is controlled by the advection of the cellular pattern by underlying flows representative of deeper layers. The <span class="hlt">magnetic</span> elements follow the differential rotation and meridional flow associated with the convection cells themselves -- supergranules rule!</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH41E..02B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH41E..02B"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Transients during Solar Flares</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balasubramaniam, K. S.; Delgado, F.; Hock, R. A.</p> <p>2013-12-01</p> <p>Solar flares result from the sudden release of energy stored in the <span class="hlt">magnetic</span> field of the solar atmosphere, attributed to <span class="hlt">magnetic</span> reconnection. In this work, we use line-of-sight magnetograms to study the changes in photospheric <span class="hlt">magnetic</span> field during large solar flares. The magnetograms are derived from observations using NASA's Helioseismic and <span class="hlt">Magnetic</span> Imager onboard the Solar Dynamics Observatory, and have a cadence of 3 minutes at a 0.5 arcsecond spatial resolution. We studied the inferred <span class="hlt">magnetic</span> <span class="hlt">flux</span> changes in 11 X-class flares from (2011-2012) and 26 M-class flares (2011). Of the 37 flares, 32 exhibited short-lived (less than 30 minutes) <span class="hlt">magnetic</span> <span class="hlt">flux</span> transients (MFTs) during the progress of the flare, similar to those by Maurya et al. (2012). We note that MFTs were co-temporal with GOES X-ray peaks. Flares with rapid rises (impulsive flares) had stronger transients while those with slower rises (gradual flares) had weak or no MFTs. Finally, flares with stronger GOES X-ray peaks (flare class) showed stronger MFTs. We believe that these changes are non-physical because the changes in the <span class="hlt">magnetic</span> field are transient (the <span class="hlt">magnetic</span> field returns to the pre-flare state) and coincide with the impulsive phase of the flare. This work supported by the US Airforce Office of Scientific Research and the AFRL/RV Space Scholar Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.5266H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.5266H"><span><span class="hlt">Magnetic</span> field line lengths inside interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Qiang; Qiu, Jiong; Krucker, Sam</p> <p>2015-07-01</p> <p>We report on the detailed and systematic study of field line twist and length distributions within <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes embedded in interplanetary coronal mass ejections (ICMEs). The Grad-Shafranov reconstruction method is utilized together with a constant-twist nonlinear force-free (Gold-Hoyle) <span class="hlt">flux</span> rope model to reveal the close relation between the field line twist and length in cylindrical <span class="hlt">flux</span> ropes, based on in situ Wind spacecraft measurements. We show that the field line twist distributions within interplanetary <span class="hlt">flux</span> ropes are inconsistent with the Lundquist model. In particular, we utilize the unique measurements of <span class="hlt">magnetic</span> field line lengths within selected ICME events as provided by Kahler et al. (<link href="#jgra51898-bib-0016"/>) based on energetic electron burst observations at 1 AU and the associated type III radio emissions detected by the Wind spacecraft. These direct measurements are compared with our model calculations to help assess the <span class="hlt">flux</span> rope interpretation of the embedded <span class="hlt">magnetic</span> structures. By using the different <span class="hlt">flux</span> rope models, we show that the in situ direct measurements of field line lengths are consistent with a <span class="hlt">flux</span> rope structure with spiral field lines of constant and low twist, largely different from that of the Lundquist model, especially for relatively large-scale <span class="hlt">flux</span> ropes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22075502','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22075502"><span>Synthetic <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> on the honeycomb lattice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorecka, Agnieszka; Gremaud, Benoit; Miniatura, Christian</p> <p>2011-08-15</p> <p>We devise experimental schemes that are able to mimic uniform and staggered <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and then further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial <span class="hlt">magnetic</span> <span class="hlt">flux</span> sustained by each cell can reach about two <span class="hlt">flux</span> quanta, thereby realizing a cold-atom analog of the Harper model with its notorious Hofstadter's butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhRvA..84b3604G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhRvA..84b3604G"><span>Synthetic <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> on the honeycomb lattice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Górecka, Agnieszka; Grémaud, Benoît; Miniatura, Christian</p> <p>2011-08-01</p> <p>We devise experimental schemes that are able to mimic uniform and staggered <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and then further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial <span class="hlt">magnetic</span> <span class="hlt">flux</span> sustained by each cell can reach about two <span class="hlt">flux</span> quanta, thereby realizing a cold-atom analog of the Harper model with its notorious Hofstadter’s butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995PhRvB..51.9118A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995PhRvB..51.9118A"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise in strongly anisotropic superconductors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashkenazy, V. D.; Jung, G.; Shapiro, B. Ya.</p> <p>1995-04-01</p> <p><span class="hlt">Magnetic</span> noise due to thermally activated movements of <span class="hlt">flux</span> vortices has been calculated taking into account fluctuations modes of nonrigid vortices. It has been shown that at low frequencies, below the crossover frequency, the noise spectrum of a layered superconductor is identical to that of a continuous material. Three regimes of spectral behavior, lnω, ω-1/2, and ω-3/2, have been predicted to be present in this frequency range. Characteristic frequencies separating different regimes depend on the geometry of the <span class="hlt">flux</span> pickup loop. At high frequencies, above the crossover frequency, bending of vortices leads to a Lorentzian shape of noise spectra. The value of the crossover frquency is not influenced by the particularities of the <span class="hlt">flux</span>-measuring arrangement and depends only on the material properties and applied <span class="hlt">magnetic</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009IAUS..257..379D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009IAUS..257..379D"><span><span class="hlt">Magnetic</span> helicity content in solar wind <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dasso, Sergio</p> <p>2009-03-01</p> <p><span class="hlt">Magnetic</span> helicity (H) is an ideal magnetohydrodynamical (MHD) invariant that quantifies the twist and linkage of <span class="hlt">magnetic</span> field lines. In magnetofluids with low resistivity, H decays much less than the energy, and it is almost conserved during times shorter than the global diffusion timescale. The extended solar corona (i.e., the heliosphere) is one of the physical scenarios where H is expected to be conserved. The amount of H injected through the photospheric level can be reorganized in the corona, and finally ejected in <span class="hlt">flux</span> ropes to the interplanetary medium. Thus, coronal mass ejections can appear as <span class="hlt">magnetic</span> clouds (MCs), which are huge twisted <span class="hlt">flux</span> <span class="hlt">tubes</span> that transport large amounts of H through the solar wind. The content of H depends on the global configuration of the structure, then, one of the main difficulties to estimate it from single spacecraft in situ observations (one point - multiple times) is that a single spacecraft can only observe a linear (one dimensional) cut of the MC global structure. Another serious difficulty is the intrinsic mixing between its spatial shape and its time evolution that occurs during the observation period. However, using some simple assumptions supported by observations, the global shape of some MCs can be unveiled, and the associated H and <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> (F) can be estimated. Different methods to quantify H and F from the analysis of in situ observations in MCs are presented in this review. Some of these methods consider a MC in expansion and going through possible <span class="hlt">magnetic</span> reconnections with its environment. We conclude that H seems to be a ‘robust’ MHD quantity in MCs, in the sense that variations of H for a given MC deduced using different methods, are typically lower than changes of H when a different cloud is considered. Quantification of H and F lets us constrain models of coronal formation and ejection of <span class="hlt">flux</span> ropes to the interplanetary medium, as well as of the dynamical evolution of MCs in the solar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994AN....315..371Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994AN....315..371Y"><span>Darkening of the Sun prior to surface appearance of sunspot <span class="hlt">flux</span> <span class="hlt">tubes</span> and magneto-thermal pulsation of the Sun</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshimura, H.</p> <p>1994-08-01</p> <p>We found an evidence that the luminosity of the Sun systematically decreased about 20 days before sunspot surface appearance by analyzing time-lag correlation of time derivatives of running mean time profiles of the data ofthe Active Cavity Radiometer Irradiance Monitor (ACRIM) I experiment on board of Solar Maximum Mission (SMM) and of the data of the daily sunspot number. This indicates that sunspot <span class="hlt">flux</span> <span class="hlt">tube</span> cooling and heat transfer blocking by the <span class="hlt">flux</span> <span class="hlt">tubes</span> start to take place in the interior of the solar convection zone well before the sunspot surface appearance. From this finding and our previous finding that the luminosity of the Sun systematically increased and the blocked heat appeared on the surface about 50 days after the sunspot surface appearance, a new view of sunspot formation and dynamics and a new view of the luminosity modulation emerged. (1) Sunspots of a solar cycle are formed from clusters of <span class="hlt">flux</span> <span class="hlt">tubes</span> which can be seen in the running time mean profile of the sunspot number as a peak with duration on the order of 100 to 200 days. (2) Heat flow is blocked by the cluster of sunspot <span class="hlt">flux</span> <span class="hlt">tubes</span> inside the convection zone to decrease the luminosity about 20 days before the surface emergence of the sunspot cluster. (3) The blocked heat appears on the surface about 50 days after the surface emergence of the cluster of sunspot <span class="hlt">flux</span> <span class="hlt">tubes</span> to heat up the surface. This appears as a thermal pulse in the running mean time profile of the ACRIM data in between the peaks of the sunspot running mean time profile. This process of heating the surface makes the temperature gradient less steep and weakens the bouyancy of sunspot <span class="hlt">flux</span> <span class="hlt">tubes</span> below the surface. (4) The radiative cooling of the surface layer by the excess heat release steepens the temperature gradient so that the bouyancy of the sub-surface <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> becomes stronger to cause the next surge of emergence of a cluster of sunspots and other <span class="hlt">magnetic</span> activities, which creates a peak in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhDT.......111S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhDT.......111S"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> dynamics in superconducting films studied by scanning Hall probe microscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stan, Gheorghe</p> <p></p> <p>In this thesis we address two different issues in the field of <span class="hlt">flux</span> dynamics in superconductors with constricted geometry. In our experiments we used scanning Hall probe microscopy to investigate the <span class="hlt">magnetic</span> field profile above the samples' surface. In the first experiment, Vortex Nucleation in Narrow Thin-Film Strips, we studied the <span class="hlt">magnetic</span> <span class="hlt">flux</span> nucleation in type-II superconducting thin-film strips of mesoscopic width. The maximum <span class="hlt">magnetic</span> field below which vortices are completely expelled from niobium narrow thin-film strips was measured for different widths. Above this threshold field we examined the field dependence of the vortex density for the studied strips. In the second experiment, The Superconducting Dripping Faucet , we analyzed, in microbridge geometry, the dynamics of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> nucleation in a one-dimensional type-I superconducting channel. For this experiment we have developed a novel high-bandwidth Hall probe to detect in real time the nucleation and subsequent motion of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> along a fabricated one-dimensional channel in a lead film. The complex dynamics exhibited by the <span class="hlt">flux</span> <span class="hlt">tubes</span> nucleating from one end of the channel shares many characteristics of the well-known dripping faucet experiment. Nonlinear time series analysis was used to investigate the dynamics of the <span class="hlt">flux</span> <span class="hlt">tubes</span> in our experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014A%26A...564A...2L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014A%26A...564A...2L"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> concentrations in a polytropic atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Losada, I. R.; Brandenburg, A.; Kleeorin, N.; Rogachevskii, I.</p> <p>2014-04-01</p> <p>Context. Strongly stratified hydromagnetic turbulence has recently been identified as a candidate for explaining the spontaneous formation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations by the negative effective <span class="hlt">magnetic</span> pressure instability (NEMPI). Much of this work has been done for isothermal layers, in which the density scale height is constant throughout. Aims: We now want to know whether earlier conclusions regarding the size of <span class="hlt">magnetic</span> structures and their growth rates carry over to the case of polytropic layers, in which the scale height decreases sharply as one approaches the surface. Methods: To allow for a continuous transition from isothermal to polytropic layers, we employ a generalization of the exponential function known as the q-exponential. This implies that the top of the polytropic layer shifts with changing polytropic index such that the scale height is always the same at some reference height. We used both mean-field simulations (MFS) and direct numerical simulations (DNS) of forced stratified turbulence to determine the resulting <span class="hlt">flux</span> concentrations in polytropic layers. Cases of both horizontal and vertical applied <span class="hlt">magnetic</span> fields were considered. Results: <span class="hlt">Magnetic</span> structures begin to form at a depth where the <span class="hlt">magnetic</span> field strength is a small fraction of the local equipartition field strength with respect to the turbulent kinetic energy. Unlike the isothermal case where stronger fields can give rise to <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations at larger depths, in the polytropic case the growth rate of NEMPI decreases for structures deeper down. Moreover, the structures that form higher up have a smaller horizontal scale of about four times their local depth. For vertical fields, <span class="hlt">magnetic</span> structures of super-equipartition strengths are formed, because such fields survive downward advection that causes NEMPI with horizontal <span class="hlt">magnetic</span> fields to reach premature nonlinear saturation by what is called the "potato-sack" effect. The horizontal cross-section of such</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998ApJ...492..804E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998ApJ...492..804E"><span>The Physics of Twisted <span class="hlt">Magnetic</span> <span class="hlt">Tubes</span> Rising in a Stratified Medium: Two-dimensional Results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Emonet, T.; Moreno-Insertis, F.</p> <p>1998-01-01</p> <p>The physics of a twisted <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> rising in a stratified medium is studied using a numerical magnetohydrodynamic (MHD) code. The problem considered is fully compressible (has no Boussinesq approximation), includes ohmic resistivity, and is two-dimensional, i.e., there is no variation of the variables in the direction of the <span class="hlt">tube</span> axis. We study a high-plasma β-case with a small ratio of radius to external pressure scale height. The results obtained will therefore be of relevance to understanding the transport of <span class="hlt">magnetic</span> <span class="hlt">flux</span> across the solar convection zone. We confirm that a sufficient twist of the field lines around the <span class="hlt">tube</span> axis can suppress the conversion of the <span class="hlt">tube</span> into two vortex rolls. For a <span class="hlt">tube</span> with a relative density deficit on the order of 1/β (the classical Parker buoyancy) and a radius smaller than the pressure scale height (R2<<H2p), the minimum amount of twist necessary corresponds to an average pitch angle on the order of sin-1 [(R/Hp)1/2]. The evolution of a <span class="hlt">tube</span> with this degree of twist is studied in detail, including the initial transient phase, the internal torsional oscillations, and the asymptotic, quasi-stationary phase. During the initial phase, the outermost, weakly <span class="hlt">magnetized</span> layers of the <span class="hlt">tube</span> are torn off its main body and endowed with vorticity. They yield a trailing <span class="hlt">magnetized</span> wake with two vortex rolls. The fraction of the total <span class="hlt">magnetic</span> <span class="hlt">flux</span> that is brought to the wake is a function of the initial degree of twist. In the weakly twisted case, most of the initial <span class="hlt">tube</span> is turned into vortex rolls. With a strong initial twist, the <span class="hlt">tube</span> rises with only a small deformation and no substantial loss of <span class="hlt">magnetic</span> <span class="hlt">flux</span>. The formation of the wake and the loss of <span class="hlt">flux</span> from the main body of the <span class="hlt">tube</span> are basically complete after the initial transient phase. A sharp interface between the <span class="hlt">tube</span> interior and the external flows is formed at the <span class="hlt">tube</span> front and sides; this area has the characteristic features of a <span class="hlt">magnetic</span> boundary layer. Its</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ASPC..462..283I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ASPC..462..283I"><span>Helioseismic Detection of Emerging <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ilonidis, S.; Zhao, J.; Kosovichev, A. G.</p> <p>2012-09-01</p> <p>Investigating the properties of <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence is one of the most important problems of solar physics. In this study we present a newly developed deep-focus time-distance measurement scheme which is able to detect strong emerging <span class="hlt">flux</span> events in the deep solar interior, before the <span class="hlt">flux</span> becomes visible on the surface. We discuss in detail the differences between our method and previous methods, and demonstrate step-by-step how the signal-to-noise (S/N) ratio is increased. The method is based on detection of perturbations in acoustic phase travel times determined from cross-covariances of solar oscillations observed on the surface. We detect strong acoustic travel-time reductions of an order of 12 - 16 seconds at a depth of 42 - 75 Mm. These acoustic anomalies are detected 1 - 2 days before high peaks in the photospheric <span class="hlt">magnetic</span> <span class="hlt">flux</span> rate implying that the average emerging speed is 0.3 - 0.6 km s-1. The results of this work contribute to our understanding of solar <span class="hlt">magnetism</span> and benefit space weather forecasting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SoPh..283..273Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SoPh..283..273Z"><span>Solar Intranetwork <span class="hlt">Magnetic</span> Elements: <span class="hlt">Flux</span> Distributions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Guiping; Wang, Jingxiu; Jin, Chunlan</p> <p>2013-04-01</p> <p>The current study aims at quantifying the <span class="hlt">flux</span> distributions of solar intranetwork (IN) <span class="hlt">magnetic</span> field based on the data taken in four quiet and two enhanced network areas with the Narrow-band Filter Imager of the Solar Optical Telescope on board the Hinode satellite. More than 14000 IN elements and 3000 NT elements were visually identified. They exhibit a <span class="hlt">flux</span> distribution function with a peak at 1 - 3×1016 Mx (maxwell) and 2 - 3×1017 Mx, respectively. We found that the IN elements contribute approximately to 52 % of the total <span class="hlt">flux</span> and an average <span class="hlt">flux</span> density of 12.4 gauss of the quiet region at any given time. By taking the lifetime of IN elements of about 3 min (Zhou et al., Solar Phys. 267, 63, 2010) into account, the IN fields are estimated to have total contributions to the solar <span class="hlt">magnetic</span> <span class="hlt">flux</span> up to 3.8×1026 Mx per day. No fundamental distinction can be identified in IN fields between the quiet and enhanced network areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005IAUS..226..281Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005IAUS..226..281Z"><span>Coronal <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes in Quadrupolar <span class="hlt">Magnetic</span> Fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yingzhi; Hu, Youqiu; Wang, Jingxiu</p> <p></p> <p>Using a 2.5-D, time-dependent ideal MHD model in spherical coordinates, we carry out a numerical study of the equilibrium properties of coronal <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in a quadrupolar background <span class="hlt">magnetic</span> field. For such a <span class="hlt">flux</span> rope system, a catastrophic occurs: the <span class="hlt">flux</span> rope is detached from the photosphere and jumps to a finite altitude with a vertical current sheet below. There is a transversal current sheet formed above the rope, and the whole system stays in quasi-equilibrium. We argue that the additional Lorentz force provided by the transversal current sheet on the <span class="hlt">flux</span> rope plays an important role in keeping the system in quasi-equilibrium in the corona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920036867&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drotation%2Bmagnetic%2Bflux','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920036867&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drotation%2Bmagnetic%2Bflux"><span>Interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> - Measurement and balance</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mccomas, D. J.; Gosling, J. T.; Phillips, J. L.</p> <p>1992-01-01</p> <p>A new method for determining the approximate amount of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in various solar wind structures in the ecliptic (and solar rotation) plane is developed using single-spacecraft measurements in interplanetary space and making certain simplifying assumptions. The method removes the effect of solar wind velocity variations and can be applied to specific, limited-extent solar wind structures as well as to long-term variations. Over the 18-month interval studied, the ecliptic plane <span class="hlt">flux</span> of coronal mass ejections was determined to be about 4 times greater than that of HFDs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21560293','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21560293"><span>Stochastic <span class="hlt">flux</span> freezing and <span class="hlt">magnetic</span> dynamo</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eyink, Gregory L.</p> <p>2011-05-15</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> conservation in turbulent plasmas at high <span class="hlt">magnetic</span> Reynolds numbers is argued neither to hold in the conventional sense nor to be entirely broken, but instead to be valid in a statistical sense associated to the ''spontaneous stochasticity'' of Lagrangian particle trajectories. The latter phenomenon is due to the explosive separation of particles undergoing turbulent Richardson diffusion, which leads to a breakdown of Laplacian determinism for classical dynamics. Empirical evidence is presented for spontaneous stochasticity, including numerical results. A Lagrangian path-integral approach is then exploited to establish stochastic <span class="hlt">flux</span> freezing for resistive hydromagnetic equations and to argue, based on the properties of Richardson diffusion, that <span class="hlt">flux</span> conservation must remain stochastic at infinite <span class="hlt">magnetic</span> Reynolds number. An important application of these results is the kinematic, fluctuation dynamo in nonhelical, incompressible turbulence at <span class="hlt">magnetic</span> Prandtl number (Pr{sub m}) equal to unity. Numerical results on the Lagrangian dynamo mechanisms by a stochastic particle method demonstrate a strong similarity between the Pr{sub m}=1 and 0 dynamos. Stochasticity of field-line motion is an essential ingredient of both. Finally, some consequences for nonlinear magnetohydrodynamic turbulence, dynamo, and reconnection are briefly considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JMMM..299...29Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JMMM..299...29Z"><span>Characteristics of soft <span class="hlt">magnetic</span> composite material under rotating <span class="hlt">magnetic</span> <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhong, J. J.; Guo, Y. G.; Zhu, J. G.; Lin, Z. W.</p> <p>2006-04-01</p> <p>This paper reports the measurement of <span class="hlt">magnetic</span> properties of the soft <span class="hlt">magnetic</span> composite material SOMALOY TM 500 in a square sample under different patterns of <span class="hlt">flux</span> density with 2D <span class="hlt">magnetic</span> excitations. The test system, principle of measurement, <span class="hlt">magnetic</span> power loss calculation, and methods of correction for misalignment of H surface sensing coils are presented. The experimental results show that although nominally isotropic, the SOMALOY TM 500 sample exhibits some anisotropy. The results are useful in the design and performance analysis of rotating electrical machines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PhDT.......101T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PhDT.......101T"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Reconstruction Methods for Shaped Tokamaks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsui, Chi-Wa.</p> <p></p> <p>The use of a variational method permits the Grad -Shafranov (GS) equation to be solved by reducing the problem of solving the 2D non-linear partial differential equation to the problem of minimizing a function of several variables. This high speed algorithm approximately solves the GS equation given a pararmeterization of the plasma boundary and the current profile (p^' and FF^' functions). We treat the current profile parameters as unknowns. The goal is to reconstruct the internal <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces of a tokamak plasma and the toroidal current density profile from the external <span class="hlt">magnetic</span> measurements. This is a classic problem of inverse equilibrium determination. The current profile parameters can be evaluated by several different matching procedures. We found that the matching of <span class="hlt">magnetic</span> <span class="hlt">flux</span> and field at the probe locations using the Biot-Savart law and <span class="hlt">magnetic</span> Green's function provides a robust method of <span class="hlt">magnetic</span> reconstruction. The matching of poloidal <span class="hlt">magnetic</span> field on the plasma surface provides a unique method of identifying the plasma current profile. However, the power of this method is greatly compromised by the experimental errors of the <span class="hlt">magnetic</span> signals. The Casing Principle (60) provides a very fast way to evaluate the plasma contribution to the <span class="hlt">magnetic</span> signals. It has the potential of being a fast matching method. We found that the performance of this method is hindered by the accuracy of the poloidal <span class="hlt">magnetic</span> field computed from the equilibrium solver. A <span class="hlt">flux</span> reconstruction package have been implemented which integrates a vacuum field solver using a filament model for the plasma, a multi-layer perceptron neural network as a interface, and the volume integration of plasma current density using Green's functions as a matching method for the current profile parameters. The <span class="hlt">flux</span> reconstruction package is applied to compare with the ASEQ and EFIT data. The results are promising. Also, we found that some plasmas in the tokamak Alcator C-Mod lie</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/873399','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/873399"><span>X-ray <span class="hlt">tube</span> with <span class="hlt">magnetic</span> electron steering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Reed, Kim W.; Turman, Bobby N.; Kaye, Ronald J.; Schneider, Larry X.</p> <p>2000-01-01</p> <p>An X-ray <span class="hlt">tube</span> uses a <span class="hlt">magnetic</span> field to steer electrons. The <span class="hlt">magnetic</span> field urges electrons toward the anode, increasing the proportion of electrons emitted from the cathode that reach desired portions of the anode and consequently contribute to X-ray production. The <span class="hlt">magnetic</span> field also urges electrons reflected from the anode back to the anode, further increasing the efficiency of the <span class="hlt">tube</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030032186','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030032186"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Compression Experiments Using Plasma Armatures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Turner, M. W.; Hawk, C. W.; Litchford, R. J.</p> <p>2003-01-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> compression reaction chambers offer considerable promise for controlling the plasma flow associated with various micronuclear/chemical pulse propulsion and power schemes, primarily because they avoid thermalization with wall structures and permit multicycle operation modes. The major physical effects of concern are the diffusion of <span class="hlt">magnetic</span> <span class="hlt">flux</span> into the rapidly expanding plasma cloud and the development of Rayleigh-Taylor instabilities at the plasma surface, both of which can severely degrade reactor efficiency and lead to plasma-wall impact. A physical parameter of critical importance to these underlying magnetohydrodynamic (MHD) processes is the <span class="hlt">magnetic</span> Reynolds number (R(sub m), the value of which depends upon the product of plasma electrical conductivity and velocity. Efficient <span class="hlt">flux</span> compression requires R(sub m) less than 1, and a thorough understanding of MHD phenomena at high <span class="hlt">magnetic</span> Reynolds numbers is essential to the reliable design and operation of practical reactors. As a means of improving this understanding, a simplified laboratory experiment has been constructed in which the plasma jet ejected from an ablative pulse plasma gun is used to investigate plasma armature interaction with <span class="hlt">magnetic</span> fields. As a prelude to intensive study, exploratory experiments were carried out to quantify the <span class="hlt">magnetic</span> Reynolds number characteristics of the plasma jet source. Jet velocity was deduced from time-of-flight measurements using optical probes, and electrical conductivity was measured using an inductive probing technique. Using air at 27-inHg vacuum, measured velocities approached 4.5 km/s and measured conductivities were in the range of 30 to 40 kS/m.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770059324&hterms=fiber+glass&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dfiber%2Bglass','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770059324&hterms=fiber+glass&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dfiber%2Bglass"><span>Low thermal <span class="hlt">flux</span> glass-fiber <span class="hlt">tubing</span> for cryogenic service</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, C. A.; Spond, D. E.</p> <p>1977-01-01</p> <p>This paper describes analytical techniques, fabrication development, and test results for composite <span class="hlt">tubing</span> that has many applications in aerospace and commercial cryogenic installations. Metal liner fabrication is discussed in detail with attention given to resistance-welded liners, fusion-welded liners, chem-milled <span class="hlt">tubing</span> liners, joining <span class="hlt">tube</span> liners and end fittings, heat treatment and leak checks. Composite overwrapping, a second method of <span class="hlt">tubing</span> fabrication, is also discussed. Test programs and analytical correlation are considered along with composite <span class="hlt">tubing</span> advantages such as minimum weight, thermal efficiency and safety and reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770059324&hterms=fusion+reliability&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dfusion%2Breliability','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770059324&hterms=fusion+reliability&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dfusion%2Breliability"><span>Low thermal <span class="hlt">flux</span> glass-fiber <span class="hlt">tubing</span> for cryogenic service</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hall, C. A.; Spond, D. E.</p> <p>1977-01-01</p> <p>This paper describes analytical techniques, fabrication development, and test results for composite <span class="hlt">tubing</span> that has many applications in aerospace and commercial cryogenic installations. Metal liner fabrication is discussed in detail with attention given to resistance-welded liners, fusion-welded liners, chem-milled <span class="hlt">tubing</span> liners, joining <span class="hlt">tube</span> liners and end fittings, heat treatment and leak checks. Composite overwrapping, a second method of <span class="hlt">tubing</span> fabrication, is also discussed. Test programs and analytical correlation are considered along with composite <span class="hlt">tubing</span> advantages such as minimum weight, thermal efficiency and safety and reliability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18233180','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18233180"><span>Nonlinear nanodevices using <span class="hlt">magnetic</span> <span class="hlt">flux</span> quanta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ooi, S; Savel'ev, Sergey; Gaifullin, M B; Mochiku, T; Hirata, K; Nori, Franco</p> <p>2007-11-16</p> <p>All devices realized so far that control the motion of <span class="hlt">magnetic</span> <span class="hlt">flux</span> quanta employ either samples with nanofabricated spatially-asymmetric potentials (which strongly limit controllability), or pristine superconductors rectifying with low-efficiency time-asymmetric oscillations of an external <span class="hlt">magnetic</span> field. Using layered Bi2Sr2CaCu2O8+delta materials, here we fabricate and simulate two efficient nonlinear superconducting devices with no spatial asymmetry. These devices can rectify with high-efficiency a two-harmonic external current dragging vortices in target directions by changing either the relative phase or the frequency ratio of the two harmonics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..DPPTP6069P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..DPPTP6069P"><span>A Low Cost Photo-Electric Detector for an Arched <span class="hlt">Flux</span> <span class="hlt">Tube</span> Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perkins, Rory; Bellan, Paul</p> <p>2008-11-01</p> <p>A low cost EUV detector is being developed for use in a laboratory experiment where two plasma-filled <span class="hlt">flux</span> <span class="hlt">tubes</span> merge in either a co-helicity or counter-helicity arrangement (J.F. Hansen, S.K.P. Tripathi, and P.M. Bellan, Phys. Plasma 2, 3177(2004)). The detector utilizes the photo-electric effect to measure EUV radiation from 10 to 120 nm (S.J. Zweben, R.J. Taylor, Plasma Physics, Vol. 23, No. 4(1981)). The detector geometry is coaxial. A cylindrical collimator capped in wire mesh was placed around the magnesium disk to collimate the field of view and reduce capacitive pick-up. <span class="hlt">Magnets</span> placed outside the collimator deflect incoming charged particles. The detector was tested in a vacuum chamber with a flash lamp located 50 cm from the detector. A current-to-voltage amplifier with a 1 microsecond rise-time read the detector's output on the test chamber. The detector output on the main experimental chamber was sent directly into 50 ohms with no amplification and produced signals above 200 mV, well above the observed noise. The rise-time for this configuration is well below 1 microsecond. An array of such detectors is currently being designed to image the <span class="hlt">flux</span> <span class="hlt">tubes</span> in this EUV range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JPhCS..30..321D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JPhCS..30..321D"><span>Noisy dynamics of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in mesoscopic cylinders</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dajka, J.; Luczka, J.; Mierzejewski, M.; Hänggi, P.</p> <p>2006-02-01</p> <p>We study <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> and currents in mesoscopic systems of cylindrical symmetry like rings, toroids and cylinders. We analyze the time evolution of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> and the characteristic time of a formation of the ordered state. We investigate how, starting from some symmetric initial state, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> or the current approach their corresponding asymptotic state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015069','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015069"><span><span class="hlt">Magnetic-Flux</span>-Compensated Voltage Divider</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mata, Carlos T.</p> <p>2005-01-01</p> <p>A <span class="hlt">magnetic-flux</span>-compensated voltage-divider circuit has been proposed for use in measuring the true potential across a component that is exposed to large, rapidly varying electric currents like those produced by lightning strikes. An example of such a component is a lightning arrester, which is typically exposed to currents of the order of tens of kiloamperes, having rise times of the order of hundreds of nanoseconds. Traditional voltage-divider circuits are not designed for <span class="hlt">magnetic-flux</span>-compensation: They contain uncompensated loops having areas large enough that the transient <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> associated with large transient currents induce spurious voltages large enough to distort voltage-divider outputs significantly. A drawing of the proposed circuit was not available at the time of receipt of information for this article. What is known from a summary textual description is that the proposed circuit would contain a total of four voltage dividers: There would be two mixed dividers in parallel with each other and with the component of interest (e.g., a lightning arrester), plus two mixed dividers in parallel with each other and in series with the component of interest in the same plane. The electrical and geometric configuration would provide compensation for induced voltages, including those attributable to asymmetry in the volumetric density of the lightning or other transient current, canceling out the spurious voltages and measuring the true voltage across the component.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...588A.150K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...588A.150K"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> concentrations from turbulent stratified convection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Käpylä, P. J.; Brandenburg, A.; Kleeorin, N.; Käpylä, M. J.; Rogachevskii, I.</p> <p>2016-04-01</p> <p>Context. The formation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations within the solar convection zone leading to sunspot formation is unexplained. Aims: We study the self-organization of initially uniform sub-equipartition <span class="hlt">magnetic</span> fields by highly stratified turbulent convection. Methods: We perform simulations of magnetoconvection in Cartesian domains representing the uppermost 8.5-24 Mm of the solar convection zone with the horizontal size of the domain varying between 34 and 96 Mm. The density contrast in the 24 Mm deep models is more than 3 × 103 or eight density scale heights, corresponding to a little over 12 pressure scale heights. We impose either a vertical or a horizontal uniform <span class="hlt">magnetic</span> field in a convection-driven turbulent flow in set-ups where no small-scale dynamos are present. In the most highly stratified cases we employ the reduced sound speed method to relax the time step constraint arising from the high sound speed in the deep layers. We model radiation via the diffusion approximation and neglect detailed radiative transfer in order to concentrate on purely magnetohydrodynamic effects. Results: We find that super-equipartition <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations are formed near the surface in cases with moderate and high density stratification, corresponding to domain depths of 12.5 and 24 Mm. The size of the concentrations increases as the box size increases and the largest structures (20 Mm horizontally near the surface) are obtained in the models that are 24 Mm deep. The field strength in the concentrations is in the range of 3-5 kG, almost independent of the magnitude of the imposed field. The amplitude of the concentrations grows approximately linearly in time. The effective <span class="hlt">magnetic</span> pressure measured in the simulations is positive near the surface and negative in the bulk of the convection zone. Its derivative with respect to the mean <span class="hlt">magnetic</span> field, however, is positive in most of the domain, which is unfavourable for the operation of the negative</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JAP...107iE704R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JAP...107iE704R"><span><span class="hlt">Magnetic</span> field simulation of <span class="hlt">magnetic</span> phase detection sensor for steam generator <span class="hlt">tube</span> in nuclear power plants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ryu, Kwon-sang; Son, Derac; Park, Duck-gun; Kim, Yong-il</p> <p>2010-05-01</p> <p><span class="hlt">Magnetic</span> phases and defects are partly produced in steam generator <span class="hlt">tubes</span> by stress and heat, because steam generator <span class="hlt">tubes</span> in nuclear power plants are used under high temperature, high pressure, and radioactivity. The <span class="hlt">magnetic</span> phases induce an error in the detection of the defects in steam generator <span class="hlt">tubes</span> by the conventional eddy current method. So a new method is needed for detecting the <span class="hlt">magnetic</span> phases in the steam generator <span class="hlt">tubes</span>. We designed a new U-type yoke which has two kinds of coils and simulated the signal by the <span class="hlt">magnetic</span> phases and defects in the Inconnel 600 <span class="hlt">tube</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23971566','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23971566"><span>Evidence from lattice data for a new particle on the worldsheet of the QCD <span class="hlt">flux</span> <span class="hlt">tube</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dubovsky, Sergei; Flauger, Raphael; Gorbenko, Victor</p> <p>2013-08-09</p> <p>We propose a new approach for the calculation of the spectrum of excitations of QCD <span class="hlt">flux</span> <span class="hlt">tubes</span>. It relies on the fact that the worldsheet theory is integrable at low energies. With this approach, energy levels can be calculated for much shorter <span class="hlt">flux</span> <span class="hlt">tubes</span> than was previously possible, allowing for a quantitative comparison with existing lattice data. The improved theoretical control makes it manifest that existing lattice data provides strong evidence for a new pseudoscalar particle localized on the QCD <span class="hlt">flux</span> <span class="hlt">tube</span>--the worldsheet axion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.871a2049O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.871a2049O"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> invasion in REBCO bulk <span class="hlt">magnets</span> with varying pre-<span class="hlt">magnetized</span> <span class="hlt">flux</span> distributions in multiple-PFM processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oka, T.; Hara, K.; Takeda, A.; Ogawa, J.; Fukui, S.; Sato, T.; Yokoyama, K.; Murakami, A.</p> <p>2017-07-01</p> <p>The motion of <span class="hlt">magnetic</span> <span class="hlt">flux</span> invading into the HTS bulk <span class="hlt">magnets</span> were experimentally studied in their pulsed field <span class="hlt">magnetization</span> processes. The authors paid attention to the effects of the shapes of the pre-<span class="hlt">magnetized</span> trapped <span class="hlt">flux</span> distributions before the successive field applications by means of varying the M-shaped distribution. We estimated the differences of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> motions between the Dy123 and Gd123 systems, which might have different J c properties of each sample. As for the Dy123 system, the increase of remaining <span class="hlt">flux</span> in the periphery region of the M-shaped distribution resulted in the decrease of <span class="hlt">flux</span>-trapping according to the promotion of <span class="hlt">flux</span> invasion. On the other hand, trapped <span class="hlt">flux</span> density has been raised to 3.4 T owing to the effective suppression of <span class="hlt">flux</span> invasion for the Gd123 bulk <span class="hlt">magnet</span>. The experiments showed that the peak heights and the positions of the formerly trapped M-shaped <span class="hlt">fluxes</span> precisely affect the heat generation and the trapped field performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6017894','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6017894"><span>The <span class="hlt">magnetic</span> topology of the plasmoid <span class="hlt">flux</span> rope in a MHD simulation of magnetotail reconnection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Birn, J.; Hesse, M.</p> <p>1989-01-01</p> <p>On the basis of a three-dimensional MHD simulation we discuss the <span class="hlt">magnetic</span> topology of a plasmoid that forms by a localized reconnection process in a magnetotail configuration including a net dawn-dusk <span class="hlt">magnetic</span> field component B/sub yN/. As a consequence of b/sub yN/ /ne/ 0 the plasmid gets a helical <span class="hlt">flux</span> rope structure rather than an isolated island or bubble structure. Initially all field lines of the plasmid <span class="hlt">flux</span> rope remain connected with the Earth, while at later times a gradually increasing amount of <span class="hlt">flux</span> <span class="hlt">tubes</span> becomes separated, connecting to either the distant boundary or to the flank boundaries. In this stage topologically different <span class="hlt">flux</span> <span class="hlt">tubes</span> become tangled and wrapped around each other, consistent with predictions on the basis of ad-hoc plasmid models. 10 refs., 8 figs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990GMS........655B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990GMS........655B"><span>The <span class="hlt">magnetic</span> topology of the plasmoid <span class="hlt">flux</span> rope in a MHD-simulation of magnetotail reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Birn, J.; Hesse, M.</p> <p></p> <p>On the basis of a 3D MHD simulation, the <span class="hlt">magnetic</span> topology of a plasmoid that forms by a localized reconnection process in a magnetotail configuration (including a net dawn-dusk <span class="hlt">magnetic</span> field component B sub y N is discussed. As a consequence of B sub y N not equalling 0, the plasmoid assumes a helical <span class="hlt">flux</span> rope structure rather than an isolated island or bubble structure. Initially all field lines of the plasmoid <span class="hlt">flux</span> rope remain connected with the earth, while at later times a gradually increasing amount of <span class="hlt">flux</span> <span class="hlt">tubes</span> becomes separated, connecting to either the distant boundary or to the flank boundaries. In this stage, topologically different <span class="hlt">flux</span> <span class="hlt">tubes</span> become tangled and wrapped around each other, consistent with predictions on the basis of an ad hoc plasmoid model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990GMS....58..655B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990GMS....58..655B"><span>The <span class="hlt">magnetic</span> topology of the plasmoid <span class="hlt">flux</span> rope in a MHD-simulation of magnetotail reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Birn, J.; Hesse, M.</p> <p></p> <p>On the basis of a three-dimensional MHD simulation we discuss the <span class="hlt">magnetic</span> topology of a plasmoid that forms by a localized reconnection process in a magnetotail configuration including a net dawn-dusk <span class="hlt">magnetic</span> field component ByN. As a consequence of ByN ≠ 0 the plasmoid assumes a helical <span class="hlt">flux</span> rope structure rather than an isolated island or bubble structure. Initially all field lines of the plasmoid <span class="hlt">flux</span> rope remain connected with the Earth, while at later times a gradually increasing amount of <span class="hlt">flux</span> <span class="hlt">tubes</span> becomes separated, connecting to either the distant boundary or to the flank boundaries. In this stage topologically different <span class="hlt">flux</span> <span class="hlt">tubes</span> become tangled and wrapped around each other, consistent with predictions on the basis of an ad-hoc plasmoid model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989pmfr.conf...27B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989pmfr.conf...27B"><span>The <span class="hlt">magnetic</span> topology of the plasmoid <span class="hlt">flux</span> rope in a MHD simulation of magnetotail reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Birn, J.; Hesse, M.</p> <p></p> <p>On the basis of a three-dimensional MHD simulation we discuss the <span class="hlt">magnetic</span> topology of a plasmoid that forms by a localized reconnection process in a magnetotail configuration including a net dawn-dusk <span class="hlt">magnetic</span> field component B sub yN. As a consequence of B sub yN ne 0 the plasmoid gets a helical <span class="hlt">flux</span> rope structure rather than an isolated island or bubble structure. Initially all field lines of the plasmoid <span class="hlt">flux</span> rope remain connected with the Earth, while at later times a gradually increasing number of <span class="hlt">flux</span> <span class="hlt">tubes</span> becomes separated, connecting to either the distant boundary or to the flank boundaries. In this stage topologically different <span class="hlt">flux</span> <span class="hlt">tubes</span> become tangled and wrapped around each other, consistent with predictions on the basis of ad hoc plasmoid models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhyC..532...40S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhyC..532...40S"><span>Stop of <span class="hlt">magnetic</span> <span class="hlt">flux</span> movement in levitating superconductor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smolyak, B. M.; Zakharov, M. S.</p> <p>2017-01-01</p> <p>A phenomenon of <span class="hlt">magnetic</span> relaxation stopping in a levitating superconductor was studied. It was experimentally shown that <span class="hlt">magnetic</span> <span class="hlt">flux</span> creep (diffusion of <span class="hlt">flux</span> lines to regions with lower vortex density) is absent in <span class="hlt">magnetic</span> suspension of the superconductor. <span class="hlt">Magnetic</span> relaxation arises, when a rigid constraint that fixes a position of the superconductor relative to a <span class="hlt">magnet</span> is imposed on a levitating object. It is assumed that oscillations of <span class="hlt">magnetic</span> structure, which is due to free oscillations of the levitating superconductor, stop <span class="hlt">magnetic</span> relaxation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MNRAS.462..960S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MNRAS.462..960S"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> stabilizing thin accretion discs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sądowski, Aleksander</p> <p>2016-10-01</p> <p>We calculate the minimal amount of large-scale poloidal <span class="hlt">magnetic</span> field that has to thread the inner, radiation-over-gas pressure dominated region of a thin disc for its thermal stability. Such a net field amplifies the <span class="hlt">magnetization</span> of the saturated turbulent state and makes it locally stable. For a 10 M⊙ black hole the minimal <span class="hlt">magnetic</span> <span class="hlt">flux</span> is 10^{24}(dot{M}/dot{M}_Edd)^{20/21} G cm2. This amount is compared with the amount of uniform <span class="hlt">magnetic</span> <span class="hlt">flux</span> that can be provided by the companion star - estimated to be in the range 1022-1024 G cm2. If accretion rate is large enough, the companion is not able to provide the required amount and such a system, if still sub-Eddington, must be thermally unstable. The peculiar variability of GRS 1915+105, an X-ray binary with the exceptionally high BH mass and near-Eddington luminosity, may result from the shortage of large-scale poloidal field of uniform polarity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014A%26A...562A..53B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014A%26A...562A..53B"><span>Mean-field and direct numerical simulations of <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations from vertical field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandenburg, A.; Gressel, O.; Jabbari, S.; Kleeorin, N.; Rogachevskii, I.</p> <p>2014-02-01</p> <p>Context. Strongly stratified hydromagnetic turbulence has previously been found to produce <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations if the domain is large enough compared with the size of turbulent eddies. Mean-field simulations (MFS) using parameterizations of the Reynolds and Maxwell stresses show a large-scale negative effective <span class="hlt">magnetic</span> pressure instability and have been able to reproduce many aspects of direct numerical simulations (DNS) regarding growth rate, shape of the resulting <span class="hlt">magnetic</span> structures, and their height as a function of <span class="hlt">magnetic</span> field strength. Unlike the case of an imposed horizontal field, for a vertical one, <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations of equipartition strength with the turbulence can be reached, resulting in <span class="hlt">magnetic</span> spots that are reminiscent of sunspots. Aims: We determine under what conditions <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations with vertical field occur and what their internal structure is. Methods: We use a combination of MFS, DNS, and implicit large-eddy simulations (ILES) to characterize the resulting <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations in forced isothermal turbulence with an imposed vertical <span class="hlt">magnetic</span> field. Results: Using DNS, we confirm earlier results that in the kinematic stage of the large-scale instability the horizontal wavelength of structures is about 10 times the density scale height. At later times, even larger structures are being produced in a fashion similar to inverse spectral transfer in helically driven turbulence. Using ILES, we find that <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations occur for Mach numbers between 0.1 and 0.7. They occur also for weaker stratification and larger turbulent eddies if the domain is wide enough. Using MFS, the size and aspect ratio of <span class="hlt">magnetic</span> structures are determined as functions of two input parameters characterizing the parameterization of the effective <span class="hlt">magnetic</span> pressure. DNS, ILES, and MFS show <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> with mean-field energies comparable to the turbulent kinetic energy. These <span class="hlt">tubes</span> can reach a length of about</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HMT...tmp...35S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HMT...tmp...35S"><span>Pool boiling of distilled water over <span class="hlt">tube</span> bundle with variable heat <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swain, Abhilas; Mohanty, Rajiva Lochan; Das, Mihir Kumar</p> <p>2017-02-01</p> <p>The experimental investigation of saturated pool boiling heat transfer of distilled water over plain <span class="hlt">tube</span> bundle, under uniform and varying heat <span class="hlt">flux</span> condition along the height are presented in this article. Experiments are carried out under various heat <span class="hlt">flux</span> configurations applied to rows of <span class="hlt">tube</span> bundles and pitch distance to diameter ratios of 1.25, 1.6 and 1.95. The wall superheats and pool boiling heat transfer coefficients over individual rows are determined. The pool boiling heat transfer coefficients for variable heat <span class="hlt">flux</span> and uniform heat <span class="hlt">flux</span> conditions are compared. The results indicate that the bundle effect is found to exist for uniform as well as variable heat <span class="hlt">flux</span> under all operating conditions in the present investigation. The variable heat <span class="hlt">flux</span> resulted in range of wall superheat being highest for decreasing heat <span class="hlt">flux</span> from bottom to top and lowest for increasing heat <span class="hlt">flux</span> from bottom to top.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HMT....53.2487S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HMT....53.2487S"><span>Pool boiling of distilled water over <span class="hlt">tube</span> bundle with variable heat <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Swain, Abhilas; Mohanty, Rajiva Lochan; Das, Mihir Kumar</p> <p>2017-08-01</p> <p>The experimental investigation of saturated pool boiling heat transfer of distilled water over plain <span class="hlt">tube</span> bundle, under uniform and varying heat <span class="hlt">flux</span> condition along the height are presented in this article. Experiments are carried out under various heat <span class="hlt">flux</span> configurations applied to rows of <span class="hlt">tube</span> bundles and pitch distance to diameter ratios of 1.25, 1.6 and 1.95. The wall superheats and pool boiling heat transfer coefficients over individual rows are determined. The pool boiling heat transfer coefficients for variable heat <span class="hlt">flux</span> and uniform heat <span class="hlt">flux</span> conditions are compared. The results indicate that the bundle effect is found to exist for uniform as well as variable heat <span class="hlt">flux</span> under all operating conditions in the present investigation. The variable heat <span class="hlt">flux</span> resulted in range of wall superheat being highest for decreasing heat <span class="hlt">flux</span> from bottom to top and lowest for increasing heat <span class="hlt">flux</span> from bottom to top.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSH54A..04G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSH54A..04G"><span>Slip Running Reconnection in <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gekelman, W. N.; Van Compernolle, B.; Vincena, S. T.; De Hass, T.</p> <p>2012-12-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> ropes are due to helical currents and form a dense carpet of arches on the surface of the sun. Occasionally one tears loose as a coronal mass ejection and its rope structure can be detected by satellites close to the earth. Current sheets can tear into filaments and these are nothing other than <span class="hlt">flux</span> ropes. Ropes are not static, they exert mutual ěc{J}×ěc{B} forces causing them to twist about each other and eventually merge. Kink instabilities cause them to violently smash into each other and reconnect at the point of contact. We report on experiments on two adjacent ropes done in the large plasma device (LAPD) at UCLA ( ne ˜ 1012, Te ˜ 6 eV, B0z=330G, Brope}\\cong{10G,trep=1 Hz). The currents and <span class="hlt">magnetic</span> fields form exotic shapes with no ignorable direction and no <span class="hlt">magnetic</span> nulls. Volumetric space-time data (70,600 spatial locations) show multiple reconnection sites with time-dependent locations. The concept of a quasi-separatrix layer (QSL), a tool to understand and visualize 3D <span class="hlt">magnetic</span> field lines reconnection without null points is introduced. Three-dimensional measurements of the QSL derived from <span class="hlt">magnetic</span> field data are presented. Within the QSL field lines that start close to one another rapidly diverge as they pass through one or more reconnection regions. The motion of <span class="hlt">magnetic</span> field lines are traced as reconnection proceeds and they are observed to slip through the regions of space where the QSL is largest. As the interaction proceeds we double the current in the ropes. This accompanied by intense heating as observed in uv light and plasma flows measured by Mach probes. The interaction of the ropes is clearly seen by vislaulizng <span class="hlt">magnetic</span> field data , as well as in images from a fast framing camera. Work supported by the Dept. of Energy and The National Science Foundation, done at the Basic Plasma Science Facility at UCLA.<span class="hlt">Magnetic</span> Field lines (measured) of three <span class="hlt">flux</span> ropes and the plasma currents associated with them</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/945549','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/945549"><span>SEED BANKS FOR <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> COMPRESSION GENERATORS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fulkerson, E S</p> <p>2008-05-14</p> <p>In recent years the Lawrence Livermore National Laboratory (LLNL) has been conducting experiments that require pulsed high currents to be delivered into inductive loads. The loads fall into two categories (1) pulsed high field <span class="hlt">magnets</span> and (2) the input stage of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Compression Generators (MFCG). Three capacitor banks of increasing energy storage and controls sophistication have been designed and constructed to drive these loads. One bank was developed for the <span class="hlt">magnet</span> driving application (20kV {approx} 30kJ maximum stored energy.) Two banks where constructed as MFCG seed banks (12kV {approx} 43kJ and 26kV {approx} 450kJ). This paper will describe the design of each bank including switching, controls, circuit protection and safety.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JHEP...10..093A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JHEP...10..093A"><span>Closed <span class="hlt">flux</span> <span class="hlt">tubes</span> in D = 2 + 1 SU( N ) gauge theories: dynamics and effective string description</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Athenodorou, Andreas; Teper, Michael</p> <p>2016-10-01</p> <p>We extend our earlier calculations of the spectrum of closed <span class="hlt">flux</span> <span class="hlt">tubes</span> in SU( N ) gauge theories in 2 + 1 dimensions, with a focus on questions raised by recent theoretical progress on the effective string action of long <span class="hlt">flux</span> <span class="hlt">tubes</span> and the world-sheet action for <span class="hlt">flux</span> <span class="hlt">tubes</span> of moderate lengths. Our new calculations in SU(4) and SU(8) provide evidence that the leading O(1 /l γ ) non-universal correction to the <span class="hlt">flux</span> <span class="hlt">tube</span> ground state energy does indeed have a power γ ≥ 7. We perform a study in SU(2), where we can traverse the length at which the Nambu-Goto ground state becomes tachyonic, to obtain an all- N view of the spectrum. Our comparison of the k = 2 <span class="hlt">flux</span> <span class="hlt">tube</span> excitation energies in SU(4) and SU(6) suggests that the massive world sheet excitation associated with the k = 2 binding has a scale that knows about the group and hence the theory in the bulk, and we comment on the potential implications of world sheet massive modes for the bulk spectrum. We provide a quantitative analysis of the surprising (near-)orthogonality of <span class="hlt">flux</span> <span class="hlt">tubes</span> carrying <span class="hlt">flux</span> in different SU( N ) representations, which implies that their screening by gluons is highly suppressed even at small N.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7382R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7382R"><span>Auroral evidence of <span class="hlt">flux</span> <span class="hlt">tube</span> blockage near noon at Saturn's magnetosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Radioti, Aikaterini; Grodent, Denis; Gérard, Jean-Claude; Southwood, David; Chané, Emmanuel; Bonfond, Bertrand; Pryor, Wayne</p> <p>2016-04-01</p> <p>We discuss plasma circulation in Saturn's magnetosphere on the basis of auroral observations. Auroral enhancements in the dawn region are suggested to be related to intense field-aligned currents generated by hot tenuous plasma carried inward in fast moving <span class="hlt">flux</span> <span class="hlt">tubes</span> as they return from tail reconnection site to the dayside. Here we demonstrate that the rotation of the auroral emission in the dawn sector is occasionally (in half of the auroral sequences examined) slowed down and blocked near noon for a couple of hours. When the blockage is prominent and persistent, we observe auroral evidence of dayside magnetopause reconnection and openign of <span class="hlt">flux</span>. A possible interpretation for our observations could be that depleted <span class="hlt">flux</span> <span class="hlt">tubes</span> at large radial distances, which rotate around Saturn are blocked in the prenoon sector between the heavy Vasyliunas cycle <span class="hlt">flux</span> <span class="hlt">tubes</span> on one side, and the magnetopause on the other side. These depleted <span class="hlt">flux</span> <span class="hlt">tubes</span> have to move above or below the current sheet to pass this blockage. The blockage of the field lines close to midday will bend them and trigger reconnection, which opens the <span class="hlt">flux</span> <span class="hlt">tubes</span> and allows for solar wind material to enter the magnetosphere. Secondly, we suggest that the circulation pattern of depleted <span class="hlt">flux</span> <span class="hlt">tubes</span> close to noon in Saturn's magnetosphere alternates between a 'blocked' and 'unblocked' state, depending on the solar wind dynamic pressure and the internal processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999AIPC..471..681K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999AIPC..471..681K"><span>Exploring ISEE-3 <span class="hlt">magnetic</span> cloud polarities with electron heat <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kahler, S. W.; Crooker, N. U.; Gosling, J. T.</p> <p>1999-06-01</p> <p>We have used solar wind electron heat <span class="hlt">fluxes</span> to determine the <span class="hlt">magnetic</span> polarities of the interplanetary <span class="hlt">magnetic</span> fields (IMF) during the ISEE-3 observations in 1978-1982. That period included 14 <span class="hlt">magnetic</span> clouds (MCs) identified by Zhang and Burlaga. The MCs have been modeled as single <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes, and it is generally assumed that they are <span class="hlt">magnetically</span> closed structures with each end of the <span class="hlt">flux</span> rope connected to the Sun. The <span class="hlt">flux</span> rope model is valid only if the <span class="hlt">magnetic</span> polarity of each MC does not change during the passage of ISEE-3 through the MC. We test this model with the heat <span class="hlt">flux</span> data, using the dominant heat <span class="hlt">flux</span> in bidirectional electron heat <span class="hlt">fluxes</span> to determine the MC polarities. The polarity changes within at least 2, and possibly 6, of the 14 MCs, meaning that those MCs can not fit the model of a single <span class="hlt">flux</span> rope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750014146','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750014146"><span>Study of Permanent <span class="hlt">Magnet</span> Focusing for Astronomical Camera <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Long, D. C.; Lowrance, J. L.</p> <p>1975-01-01</p> <p>A design is developed of a permanent <span class="hlt">magnet</span> assembly (PMA) useful as the <span class="hlt">magnetic</span> focusing unit for the 35 and 70 mm (diagonal) format SEC <span class="hlt">tubes</span>. Detailed PMA designs for both <span class="hlt">tubes</span> are given, and all data on their <span class="hlt">magnetic</span> configuration, size, weight, and structure of <span class="hlt">magnetic</span> shields adequate to screen the camera <span class="hlt">tube</span> from the earth's <span class="hlt">magnetic</span> field are presented. A digital computer is used for the PMA design simulations, and the expected operational performance of the PMA is ascertained through the calculation of a series of photoelectron trajectories. A large volume where the <span class="hlt">magnetic</span> field uniformity is greater than 0.5% appears obtainable, and the point spread function (PSF) and modulation transfer function(MTF) indicate nearly ideal performance. The MTF at 20 cycles per mm exceeds 90%. The weight and volume appear tractable for the large space telescope and ground based application.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150007699','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150007699"><span>Simulations of Emerging <span class="hlt">Magnetic</span> <span class="hlt">Flux</span>. II. The Formation of Unstable Coronal <span class="hlt">Flux</span> Ropes and the Initiation of Coronal Mass Ejections</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Leake, James E.; Linton, Mark G.; Antiochos, Spiro K.</p> <p>2014-01-01</p> <p>We present results from three-dimensional magnetohydrodynamic simulations of the emergence of a twisted convection zone <span class="hlt">flux</span> <span class="hlt">tube</span> into a pre-existing coronal dipole field. As in previous simulations, following the partial emergence of the sub-surface <span class="hlt">flux</span> into the corona, a combination of vortical motions and internal <span class="hlt">magnetic</span> reconnection forms a coronal <span class="hlt">flux</span> rope. Then, in the simulations presented here, external reconnection between the emerging field and the pre-existing dipole coronal field allows further expansion of the coronal <span class="hlt">flux</span> rope into the corona. After sufficient expansion, internal reconnection occurs beneath the coronal <span class="hlt">flux</span> rope axis, and the <span class="hlt">flux</span> rope erupts up to the top boundary of the simulation domain (approximately 36 Mm above the surface).We find that the presence of a pre-existing field, orientated in a direction to facilitate reconnection with the emerging field, is vital to the fast rise of the coronal <span class="hlt">flux</span> rope. The simulations shown in this paper are able to self-consistently create many of the surface and coronal signatures used by coronal mass ejection (CME) models. These signatures include surface shearing and rotational motions, quadrupolar geometry above the surface, central sheared arcades reconnecting with oppositely orientated overlying dipole fields, the formation of coronal <span class="hlt">flux</span> ropes underlying potential coronal field, and internal reconnection which resembles the classical flare reconnection scenario. This suggests that proposed mechanisms for the initiation of a CME, such as "<span class="hlt">magnetic</span> breakout," are operating during the emergence of new active regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22356846','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22356846"><span>Simulations of emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span>. II. The formation of unstable coronal <span class="hlt">flux</span> ropes and the initiation of coronal mass ejections</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Leake, James E.; Linton, Mark G.; Antiochos, Spiro K.</p> <p>2014-05-20</p> <p>We present results from three-dimensional magnetohydrodynamic simulations of the emergence of a twisted convection zone <span class="hlt">flux</span> <span class="hlt">tube</span> into a pre-existing coronal dipole field. As in previous simulations, following the partial emergence of the sub-surface <span class="hlt">flux</span> into the corona, a combination of vortical motions and internal <span class="hlt">magnetic</span> reconnection forms a coronal <span class="hlt">flux</span> rope. Then, in the simulations presented here, external reconnection between the emerging field and the pre-existing dipole coronal field allows further expansion of the coronal <span class="hlt">flux</span> rope into the corona. After sufficient expansion, internal reconnection occurs beneath the coronal <span class="hlt">flux</span> rope axis, and the <span class="hlt">flux</span> rope erupts up to the top boundary of the simulation domain (∼36 Mm above the surface). We find that the presence of a pre-existing field, orientated in a direction to facilitate reconnection with the emerging field, is vital to the fast rise of the coronal <span class="hlt">flux</span> rope. The simulations shown in this paper are able to self-consistently create many of the surface and coronal signatures used by coronal mass ejection (CME) models. These signatures include surface shearing and rotational motions, quadrupolar geometry above the surface, central sheared arcades reconnecting with oppositely orientated overlying dipole fields, the formation of coronal <span class="hlt">flux</span> ropes underlying potential coronal field, and internal reconnection which resembles the classical flare reconnection scenario. This suggests that proposed mechanisms for the initiation of a CME, such as '<span class="hlt">magnetic</span> breakout', are operating during the emergence of new active regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..282..127B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..282..127B"><span>Influence of the crustal <span class="hlt">magnetic</span> field on the Mars aurora electron <span class="hlt">flux</span> and UV brightness</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bisikalo, D. V.; Shematovich, V. I.; Gérard, J.-C.; Hubert, B.</p> <p>2017-01-01</p> <p>Observations with the SPICAM instrument on board Mars Express have shown the occasional presence of localized ultraviolet nightside emissions associated with enhanced energetic electron <span class="hlt">fluxes</span>. These features generally occur in regions with significant radial crustal <span class="hlt">magnetic</span> field. We use a Monte-Carlo electron transport model to investigate the role of the <span class="hlt">magnetic</span> field on the downward and upward electron <span class="hlt">fluxes</span>, the brightness and the emitted power of auroral emissions. Simulations based on an ASPERA-3 measured auroral electron precipitation indicate that <span class="hlt">magnetic</span> mirroring leads to an intensification of the energy <span class="hlt">flux</span> carried by upward moving electrons- from about 20% in the absence of crustal <span class="hlt">magnetic</span> field up to 33-78% when <span class="hlt">magnetic</span> field is included depending on <span class="hlt">magnetic</span> field topology. Conservation of the particle <span class="hlt">flux</span> in a <span class="hlt">flux</span> <span class="hlt">tube</span> implies that the presence of the B-field does not appreciably modify the emission rate profiles for an initially isotropic pitch angle distribution. However, we find that crustal <span class="hlt">magnetic</span> field results in increase of the upward electron <span class="hlt">flux</span>, and, consequently, in reduction of the total auroral brightness for given energy <span class="hlt">flux</span> of precipitating electrons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820016545','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820016545"><span>Linear <span class="hlt">magnetic</span> motor/generator. [to generate electric energy using <span class="hlt">magnetic</span> <span class="hlt">flux</span> for spacecraft power supply</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Studer, P. A. (Inventor)</p> <p>1982-01-01</p> <p>A linear <span class="hlt">magnetic</span> motor/generator is disclosed which uses <span class="hlt">magnetic</span> <span class="hlt">flux</span> to provide mechanical motion or electrical energy. The linear <span class="hlt">magnetic</span> motor/generator includes an axially movable actuator mechanism. A permament <span class="hlt">magnet</span> mechanism defines a first <span class="hlt">magnetic</span> <span class="hlt">flux</span> path which passes through a first end portion of the actuator mechanism. Another permament <span class="hlt">magnet</span> mechanism defines a second <span class="hlt">magnetic</span> <span class="hlt">flux</span> path which passes through a second end portion of the actuator mechanism. A drive coil defines a third <span class="hlt">magnetic</span> <span class="hlt">flux</span> path passing through a third central portion of the actuator mechanism. A drive coil selectively adds <span class="hlt">magnetic</span> <span class="hlt">flux</span> to and subtracts <span class="hlt">magnetic</span> <span class="hlt">flux</span> from <span class="hlt">magnetic</span> <span class="hlt">flux</span> flowing in the first and second <span class="hlt">magnetic</span> <span class="hlt">flux</span> path.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22270544','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22270544"><span>THE BEHAVIOR OF TRANSVERSE WAVES IN NONUNIFORM SOLAR <span class="hlt">FLUX</span> <span class="hlt">TUBES</span>. I. COMPARISON OF IDEAL AND RESISTIVE RESULTS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Soler, Roberto; Terradas, Jaume; Oliver, Ramón; Goossens, Marcel</p> <p>2013-11-10</p> <p>Magnetohydrodynamic (MHD) waves are ubiquitously observed in the solar atmosphere. Kink waves are a type of transverse MHD waves in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> that are damped due to resonant absorption. The theoretical study of kink MHD waves in solar <span class="hlt">flux</span> <span class="hlt">tubes</span> is usually based on the simplification that the transverse variation of density is confined to a nonuniform layer much thinner than the radius of the <span class="hlt">tube</span>, i.e., the so-called thin boundary approximation. Here, we develop a general analytic method to compute the dispersion relation and the eigenfunctions of ideal MHD waves in pressureless <span class="hlt">flux</span> <span class="hlt">tubes</span> with transversely nonuniform layers of arbitrary thickness. Results for kink waves are produced and compared with fully numerical resistive MHD eigenvalue computations in the limit of small resistivity. We find that the frequency and resonant damping rate are the same in both ideal and resistive cases. The actual results for thick nonuniform layers deviate from the behavior predicted in the thin boundary approximation and strongly depend on the shape of the nonuniform layer. The eigenfunctions in ideal MHD are very different from those in resistive MHD. The ideal eigenfunctions display a global character regardless of the thickness of the nonuniform layer, while the resistive eigenfunctions are localized around the resonance and are indistinguishable from those of ordinary resistive Alfvén modes. Consequently, the spatial distribution of wave energy in the ideal and resistive cases is dramatically different. This poses a fundamental theoretical problem with clear observational consequences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvE..93e3205K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvE..93e3205K"><span>Nonlinear oscillations of coalescing <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kolotkov, Dmitrii Y.; Nakariakov, Valery M.; Rowlands, George</p> <p>2016-05-01</p> <p>An analytical model of highly nonlinear oscillations occurring during a coalescence of two <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes, based upon two-fluid hydrodynamics, is developed. The model accounts for the effect of electric charge separation, and describes perpendicular oscillations of the current sheet formed by the coalescence. The oscillation period is determined by the current sheet thickness, the plasma parameter β , and the oscillation amplitude. The oscillation periods are typically greater or about the ion plasma oscillation period. In the nonlinear regime, the oscillations of the ion and electron concentrations have a shape of a narrow symmetric spikes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2675569','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2675569"><span><span class="hlt">Magnetic</span> stabilization and vorticity in submillimeter paramagnetic liquid <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Coey, J. Michael D.; Aogaki, Ryoichi; Byrne, Fiona; Stamenov, Plamen</p> <p>2009-01-01</p> <p>It is possible to suppress convection and dispersion of a paramagnetic liquid by means of a <span class="hlt">magnetic</span> field. A <span class="hlt">tube</span> of paramagnetic liquid can be stabilized in water along a ferromagnetic track in a vertical <span class="hlt">magnetic</span> field, but not in a horizontal field. Conversely, an “antitube” of water can be stabilized in a paramagnetic liquid along the same track in a transverse horizontal field, but not in a vertical field. The stability arises from the interaction of the induced moment in the solution with the <span class="hlt">magnetic</span> field gradient in the vicinity of the track. The <span class="hlt">magnetic</span> force causes the <span class="hlt">tube</span> of paramagnetic liquid to behave as if it were encased by an elastic membrane whose cross-section is modified by gravitational forces and Maxwell stress. Convection from the <span class="hlt">tube</span> to its surroundings is inhibited, but not diffusion. Liquid motion within the paramagnetic <span class="hlt">tube</span>, however, exhibits vorticity in <span class="hlt">tubes</span> of diameter 1 mm or less—conditions where classical pipe flow would be perfectly streamline, and mixing extremely slow. The liquid <span class="hlt">tube</span> is found to slide along the track almost without friction. Paramagnetic liquid <span class="hlt">tubes</span> and antitubes offer appealing new prospects for mass transport, microfluidics, and electrodeposition. PMID:19416873</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19416873','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19416873"><span><span class="hlt">Magnetic</span> stabilization and vorticity in submillimeter paramagnetic liquid <span class="hlt">tubes</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coey, J Michael D; Aogaki, Ryoichi; Byrne, Fiona; Stamenov, Plamen</p> <p>2009-06-02</p> <p>It is possible to suppress convection and dispersion of a paramagnetic liquid by means of a <span class="hlt">magnetic</span> field. A <span class="hlt">tube</span> of paramagnetic liquid can be stabilized in water along a ferromagnetic track in a vertical <span class="hlt">magnetic</span> field, but not in a horizontal field. Conversely, an "antitube" of water can be stabilized in a paramagnetic liquid along the same track in a transverse horizontal field, but not in a vertical field. The stability arises from the interaction of the induced moment in the solution with the <span class="hlt">magnetic</span> field gradient in the vicinity of the track. The <span class="hlt">magnetic</span> force causes the <span class="hlt">tube</span> of paramagnetic liquid to behave as if it were encased by an elastic membrane whose cross-section is modified by gravitational forces and Maxwell stress. Convection from the <span class="hlt">tube</span> to its surroundings is inhibited, but not diffusion. Liquid motion within the paramagnetic <span class="hlt">tube</span>, however, exhibits vorticity in <span class="hlt">tubes</span> of diameter 1 mm or less--conditions where classical pipe flow would be perfectly streamline, and mixing extremely slow. The liquid <span class="hlt">tube</span> is found to slide along the track almost without friction. Paramagnetic liquid <span class="hlt">tubes</span> and antitubes offer appealing new prospects for mass transport, microfluidics, and electrodeposition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1176427','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1176427"><span>Permanent-<span class="hlt">magnet</span> switched-<span class="hlt">flux</span> machine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Trzynadlowski, Andrzej M.; Qin, Ling</p> <p>2011-06-14</p> <p>A permanent-<span class="hlt">magnet</span> switched-<span class="hlt">flux</span> (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-<span class="hlt">magnets</span> (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1176203','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1176203"><span>Permanent-<span class="hlt">magnet</span> switched-<span class="hlt">flux</span> machine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Trzynadlowski, Andrzej M.; Qin, Ling</p> <p>2010-01-12</p> <p>A permanent-<span class="hlt">magnet</span> switched-<span class="hlt">flux</span> (PMSF) device has a ferromagnetic outer stator mounted to a shaft about a central axis extending axially through the PMSF device. Pluralities of top and bottom stator poles are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the ferromagnetic outer stator. A ferromagnetic inner rotor is coupled to the shaft and has i) a rotor core having a core axis co-axial with the central axis; and ii) first and second discs having respective outer edges with first and second pluralities of permanent <span class="hlt">magnets</span> (PMs) mounted in first and second circles, radially outwardly from the rotor core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1176440','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1176440"><span>Permanent-<span class="hlt">magnet</span> switched-<span class="hlt">flux</span> machine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Trzynadlowski, Andrzej M.; Qin, Ling</p> <p>2012-02-21</p> <p>A permanent-<span class="hlt">magnet</span> switched-<span class="hlt">flux</span> (PMSF) device has an outer rotor mounted to a shaft about a central axis extending axially through the PMSF device. First and second pluralities of permanent-<span class="hlt">magnets</span> (PMs) are respectively mounted in first and second circles, radially outwardly in first and second transverse planes extending from first and second sections of the central axis adjacent to an inner surface of the outer rotor. An inner stator is coupled to the shaft and has i) a stator core having a core axis co-axial with the central axis; and ii) first and second pluralities of stator poles mounted in first and second circles, radially outwardly from the stator core axis in the first and second transverse planes. The first and second pluralities of PMs each include PMs of alternating polarity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5761206','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5761206"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise in copper oxide superconductors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferrari, M.J.</p> <p>1991-11-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise and <span class="hlt">flux</span> creep in thin films and single crystals of YBa{sub 2}Cu{sub 3}O{sub 7-x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}, Tl{sub 2}Ca{sub 2}Ba{sub 2}Cu{sub 3}O{sub x}, and TlCa{sub 2}Ba{sub 2}Cu{sub 3}O{sub x} are measured with a superconducting quantum interference device (SQUID). The noise power spectrum generally scales as 1/f (f is frequency) from 1 Hz to 1 kHz, increases with temperature, and decreases in higher-quality films. It is proportional to the <span class="hlt">magnetic</span> field B in which the sample is cooled, at least in the range 0.1 mT < B < 3 mT. A model of thermally activated vortex motion is developed which explains the dependence of the noise on frequency, temperature, current, and applied <span class="hlt">magnetic</span> field. The pinning potential is idealized as an ensemble of double wells, each with a different activation energy separating the two states. From the noise measurements, this model yields the distribution of pinning energies in the samples, the vortex hopping distance, the number density of mobile vortices, and the restoring force on a vortex at a typical pinning site. The distribution of pinning energies in YBa{sub 2}Cu{sub 3}O{sub 7-x} shows a broad peak below 0.1 eV. The small ambient <span class="hlt">magnetic</span> field, and the detection of noise even in the absence of a driving force, insure that the measured pinning energies are characteristic of isolated vortices near thermal equilibrium. The observed vortex density in fields much less than 0.1 mT is too large to be explained by the ambient field, suggesting a mechanism intrinsic to the sample which produces trapped vortices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...825..109Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...825..109Z"><span>Downward Catastrophe of Solar <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Quanhao; Wang, Yuming; Hu, Youqiu; Liu, Rui</p> <p>2016-07-01</p> <p>2.5-dimensional time-dependent ideal magnetohydrodynamic (MHD) models in Cartesian coordinates were used in previous studies to seek MHD equilibria involving a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope embedded in a bipolar, partially open background field. As demonstrated by these studies, the equilibrium solutions of the system are separated into two branches: the <span class="hlt">flux</span> rope sticks to the photosphere for solutions at the lower branch but is suspended in the corona for those at the upper branch. Moreover, a solution originally at the lower branch jumps to the upper, as the related control parameter increases and reaches a critical value, and the associated jump is here referred to as an upward catastrophe. The present paper advances these studies in three aspects. First, the <span class="hlt">magnetic</span> field is changed to be force-free; the system still experiences an upward catastrophe with an increase in each control parameter. Second, under the force-free approximation, there also exists a downward catastrophe, characterized by the jump of a solution from the upper branch to the lower. Both catastrophes are irreversible processes connecting the two branches of equilibrium solutions so as to form a cycle. Finally, the <span class="hlt">magnetic</span> energy in the numerical domain is calculated. It is found that there exists a <span class="hlt">magnetic</span> energy release for both catastrophes. The Ampère's force, which vanishes everywhere for force-free fields, appears only during the catastrophes and does positive work, which serves as a major mechanism for the energy release. The implications of the downward catastrophe and its relevance to solar activities are briefly discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MeScT..26g5005W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MeScT..26g5005W"><span>Automatic <span class="hlt">magnetic</span> <span class="hlt">flux</span> measurement of micro plastic-<span class="hlt">magnetic</span> rotors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Qingdong; Lin, Mingxing; Song, Aiwei</p> <p>2015-07-01</p> <p>Micro plastic-<span class="hlt">magnetic</span> rotors of various sizes and shapes are widely used in industry, their <span class="hlt">magnetic</span> <span class="hlt">flux</span> measurement is one of the most important links in the production process, and therefore some technologies should be adopted to improve the measurement precision and efficiency. In this paper, the automatic measurement principle of micro plastic-<span class="hlt">magnetic</span> rotors is proposed and the integration time constant and the integrator drift’s suppression and compensation in the measurement circuit are analyzed. Two other factors influencing the measurement precision are also analyzed, including the relative angles between the rotor <span class="hlt">magnetic</span> poles and the measurement coil, and the starting point of the rotors in the coil where the measurement begins. An instrument is designed to measure the <span class="hlt">magnetic</span> <span class="hlt">flux</span> of the rotors. Measurement results show that the measurement error is within  ±1%, which meets the basic requirements in industry application, and the measurement efficiency is increased by 10 times, which can cut down labor cost and management cost when compared with manual measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005A%26A...444..961A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005A%26A...444..961A"><span>Current sheet formation in quasi-separatrix layers and hyperbolic <span class="hlt">flux</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aulanier, G.; Pariat, E.; Démoulin, P.</p> <p>2005-12-01</p> <p>In 3D <span class="hlt">magnetic</span> field configurations, quasi-separatrix layers (QSLs) are defined as volumes in which field lines locally display strong gradients of connectivity. Considering QSLs both as the preferential locations for current sheet development and <span class="hlt">magnetic</span> reconnection, in general, and as a natural model for solar flares and coronal heating, in particular, has been strongly debated issues over the past decade. In this paper, we perform zero-β resistive MHD simulations of the development of electric currents in smooth <span class="hlt">magnetic</span> configurations which are, strictly speaking, bipolar though they are formed by four <span class="hlt">flux</span> concentrations, and whose potential fields contain QSLs. The configurations are driven by smooth and large-scale sub-Alfvénic footpoint motions. Extended electric currents form naturally in the configurations, which evolve through a sequence of quasi non-linear force-free equilibria. Narrow current layers also develop. They spontaneously form at small scales all around the QSLs, whatever the footpoint motions are. For long enough motions, the strongest currents develop where the QSLs are the thinnest, namely at the Hyperbolic <span class="hlt">Flux</span> <span class="hlt">Tube</span> (HFT), which generalizes the concept of separator. These currents progressively take the shape of an elongated sheet, whose formation is associated with a gradual steepening of the <span class="hlt">magnetic</span> field gradients over tens of Alfvén times, due to the different motions applied to the field lines which pass on each side of the HFT. Our model then self-consistently accounts for the long-duration energy storage prior to a flare, followed by a switch-on of reconnection when the currents reach the dissipative scale at the HFT. In configurations whose potential fields contain broader QSLs, when the <span class="hlt">magnetic</span> field gradients reach the dissipative scale, the currents at the HFT reach higher magnitudes. This implies that major solar flares which are not related to an early large-scale ideal instability, must occur in regions whose</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.779a2046W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.779a2046W"><span>Signatures of <span class="hlt">Flux</span> <span class="hlt">Tube</span> Fragmentation and Strangeness Correlations in pp Collisions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wong, Cheuk-Yin</p> <p>2017-01-01</p> <p>In the fragmentation of a color <span class="hlt">flux</span> <span class="hlt">tube</span> in high-energy pp collisions or e +-e‑ annihilations, the production of pairs along a color <span class="hlt">flux</span> <span class="hlt">tube</span> precedes the fragmentation of the <span class="hlt">tube</span>. The local conservation laws in the production of these pairs will lead to the correlations of adjacently produced hadrons. As a consequence, the fragmentation of a <span class="hlt">flux</span> <span class="hlt">tube</span> will yield a many-hadron correlation in the form of a chain of hadrons ordered in rapidity, with adjacent hadrons correlated in charges, flavor contents, and azimuthal angles. It will also lead to a two-hadron angular correlation between two hadrons with opposite charges or strangeness that is suppressed at Δϕ ~ 0 but enhanced at Δϕ ~ π, within a rapidity window Δy~1/(dN/dy).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930046826&hterms=Fossil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DFossil','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930046826&hterms=Fossil&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DFossil"><span>Topology of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes and formation of fossil <span class="hlt">flux</span> transfer events and boundary layer plasmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, L. C.; Ma, Z. W.; Fu, Z. F.; Otto, A.</p> <p>1993-01-01</p> <p>A mechanism for the formation of fossil <span class="hlt">flux</span> transfer events and the low-level boundary layer within the framework of multiple X-line reconnection is proposed. Attention is given to conditions for which the bulk of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in a <span class="hlt">flux</span> rope of finite extent has a simple <span class="hlt">magnetic</span> topology, where the four possible connections of <span class="hlt">magnetic</span> field lines are: IMF to MSP, MSP to IMF, IMF to IMF, and MSP to MSP. For a sufficient relative shift of the X lines, <span class="hlt">magnetic</span> <span class="hlt">flux</span> may enter a <span class="hlt">flux</span> rope from the magnetosphere and exit into the magnetosphere. This process leads to the formation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes which contain a considerable amount of magnetosheath plasma on closed magnetospheric field lines. This process is discussed as a possible explanation for the formation of fossil <span class="hlt">flux</span> transfer events in the magnetosphere and the formation of the low-latitude boundary layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930046826&hterms=Fossils&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DFossils','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930046826&hterms=Fossils&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DFossils"><span>Topology of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes and formation of fossil <span class="hlt">flux</span> transfer events and boundary layer plasmas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, L. C.; Ma, Z. W.; Fu, Z. F.; Otto, A.</p> <p>1993-01-01</p> <p>A mechanism for the formation of fossil <span class="hlt">flux</span> transfer events and the low-level boundary layer within the framework of multiple X-line reconnection is proposed. Attention is given to conditions for which the bulk of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in a <span class="hlt">flux</span> rope of finite extent has a simple <span class="hlt">magnetic</span> topology, where the four possible connections of <span class="hlt">magnetic</span> field lines are: IMF to MSP, MSP to IMF, IMF to IMF, and MSP to MSP. For a sufficient relative shift of the X lines, <span class="hlt">magnetic</span> <span class="hlt">flux</span> may enter a <span class="hlt">flux</span> rope from the magnetosphere and exit into the magnetosphere. This process leads to the formation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes which contain a considerable amount of magnetosheath plasma on closed magnetospheric field lines. This process is discussed as a possible explanation for the formation of fossil <span class="hlt">flux</span> transfer events in the magnetosphere and the formation of the low-latitude boundary layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvL.111f2006D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvL.111f2006D"><span>Evidence from Lattice Data for a New Particle on the Worldsheet of the QCD <span class="hlt">Flux</span> <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dubovsky, Sergei; Flauger, Raphael; Gorbenko, Victor</p> <p>2013-08-01</p> <p>We propose a new approach for the calculation of the spectrum of excitations of QCD <span class="hlt">flux</span> <span class="hlt">tubes</span>. It relies on the fact that the worldsheet theory is integrable at low energies. With this approach, energy levels can be calculated for much shorter <span class="hlt">flux</span> <span class="hlt">tubes</span> than was previously possible, allowing for a quantitative comparison with existing lattice data. The improved theoretical control makes it manifest that existing lattice data provides strong evidence for a new pseudoscalar particle localized on the QCD <span class="hlt">flux</span> tube—the worldsheet axion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990A%26A...232..536H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990A%26A...232..536H"><span>Stability of cool <span class="hlt">flux</span> <span class="hlt">tubes</span> in the solar chromosphere. II - Non-linear dynamical behaviour</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hassan, S. S.; Kneer, F.</p> <p>1990-06-01</p> <p>A single vertical cool <span class="hlt">flux</span> <span class="hlt">tube</span> in the solar chromosphere is focused upon for stability studies. The analysis of a previous study by Hasan and Kneer (1986) is extended to the nonlinear regime with a view to examining the consequences of having self-exciting mechanisms of oscillations above the photosphere. In particular, the possibility of whether the motions driven by the convective instability caused by the presence of CO could extract sufficient energy from the radiation field near the Tmin region of empirical models and deposit it in higher layers to produce chromospheric heating is investigated. The time evolution of this instability is followed by solving the MHD equations in the thin <span class="hlt">flux</span> <span class="hlt">tube</span> approximation. The analysis includes energy exchange with the radiation field. The simulations of a <span class="hlt">flux</span> <span class="hlt">tube</span> with a transmitting upper boundary show that the average energy <span class="hlt">flux</span> in the oscillations is inadequate for chromospheric heating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUSMSM31B..04R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUSMSM31B..04R"><span>Particle Energization on <span class="hlt">Flux</span> <span class="hlt">Tubes</span> Threading the Auroral Ionososphere - a Proposed Polar Orbiting Satellite Mission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rankin, R.; Sydorenko, D.; Watt, C.</p> <p>2009-05-01</p> <p>Observations from the NASA POLAR and FAST missions reveal that Alfven waves are intimately associated with electron and ion particle acceleration in Earth's magnetosphere. Data from POLAR shows intense geomagnetic field-aligned wave Poynting <span class="hlt">flux</span> near and within the plasma sheet tail lobe boundary. The corresponding UVI auroral imaging provides strong, but nevertheless circumstantial evidence that the associated electron acceleration powers auroral emissions above the ionosphere. To explain the data, we present results of modeling that agree with observations of Alfven wave activity, and describe the characteristics of the resulting wave-particle interactions along the entire extent of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span>. Model results using the Vlasov-Maxwell equations reveal detailed characteristics of the electron distribution functions observed by POLAR, while two-fluid modeling of the resulting ion dynamics is shown to agree with observations of up-flowing ion beams. We argue that missions such as FAST and POLAR reveal the need for more detailed observations at high altitude, on the order of 4-5Re. Such an opportunity is presented by the decision by Canada to launch two Polar Communications Weather (PCW) satellites that sample the relevant region of Geospace within which acceleration by Alfven waves is optimal. We discuss how a well-instrumented PCW mission would be used to demonstrate closure on the nature of Alfven wave-induced particle acceleration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950059826&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Delectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950059826&hterms=electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Delectric%2Bcurrent"><span>Line-of-sight <span class="hlt">magnetic</span> <span class="hlt">flux</span> imbalances caused by electric currents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gary, G. Allen; Rabin, Douglas</p> <p>1995-01-01</p> <p>Several physical and observational effects contribute to the significant imbalances of <span class="hlt">magnetic</span> <span class="hlt">flux</span> that are often observed in active regions. We consider an effect not previously treated: the influence of electric currents in the photosphere. Electric currents can cause a line-of-sight <span class="hlt">flux</span> imbalance because of the directionality of the <span class="hlt">magnetic</span> field they produce. Currents associated with <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> produce larger imbalances than do smoothly-varying distributions of <span class="hlt">flux</span> and current. We estimate the magnitude of this effect for current densities, total currents, and <span class="hlt">magnetic</span> geometry consistent with observations. The expected imbalances lie approximately in the range 0-15%, depending on the character of the current-carying fields and the angle from which they are viewed. Observationally, current-induced <span class="hlt">flux</span> imbalances could be indicated by a statistical dependence of the imbalance on angular distance from disk center. A general study of <span class="hlt">magnetic</span> <span class="hlt">flux</span> balance in active regions is needed to determine the relative importance of other- probably larger- effects such as dilute <span class="hlt">flux</span> (too weak to measure or rendered invisible by radiative transfer effects), merging with weak background fields, and long-range connections between active regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1038950','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1038950"><span>Development and Technology Transfer of the Syncro Blue <span class="hlt">Tube</span> (Gabriel) <span class="hlt">Magnetically</span> GuidedFeeding <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2017-06-01</p> <p><span class="hlt">magnetically</span> guided version.. - pH paper color changes from red to yellow to green as the <span class="hlt">tube</span> advances distally. - Fresh bile is retrieved once the...conclusion reached that it was not safe for clinical application. 16 Bedside confirmation using pH paper : pH paper is provided with each feeding...<span class="hlt">tube</span> pre-cut on a water absorbing, disposable towel . This resulted in reduction of procedure time. We recommend observing absence of decline in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22370328','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22370328"><span>Energy propagation by transverse waves in multiple <span class="hlt">flux</span> <span class="hlt">tube</span> systems using filling factors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Van Doorsselaere, T.; Gijsen, S. E.; Andries, J.; Verth, G. E-mail: stief.gijsen@wis.kuleuven.be E-mail: g.verth@sheffield.ac.uk</p> <p>2014-11-01</p> <p>In the last few years, it has been found that transverse waves are present at all times in coronal loops or spicules. Their energy has been estimated with an expression derived for bulk Alfvén waves in homogeneous media, with correspondingly uniform wave energy density and <span class="hlt">flux</span>. The kink mode, however, is localized in space with the energy density and <span class="hlt">flux</span> dependent on the position in the cross-sectional plane. The more relevant quantities for the kink mode are the integrals of the energy density and <span class="hlt">flux</span> over the cross-sectional plane. The present paper provides an approximation to the energy propagated by kink modes in an ensemble of <span class="hlt">flux</span> <span class="hlt">tubes</span> by means of combining the analysis of single <span class="hlt">flux</span> <span class="hlt">tube</span> kink oscillations with a filling factor for the <span class="hlt">tube</span> cross-sectional area. This finally allows one to compare the expressions for energy <span class="hlt">flux</span> of Alfvén waves with an ensemble of kink waves. We find that the correction factor for the energy in kink waves, compared to the bulk Alfvén waves, is between f and 2f, where f is the density filling factor of the ensemble of <span class="hlt">flux</span> <span class="hlt">tubes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23266314','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23266314"><span>[Fallopian <span class="hlt">tube</span> disease on <span class="hlt">magnetic</span> resonance imaging].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>La Parra Casado, C; Molina Fàbrega, R; Forment Navarro, M; Cano Gimeno, J</p> <p>2013-09-01</p> <p>Knowledge about fallopian <span class="hlt">tube</span> disease is essential in the assessment of the pelvis in female patients. Primary and secondary changes in the <span class="hlt">tubes</span> vary widely, regardless of whether associated changes in the ovaries are present. Ultrasonography is the initial technique in the study of adnexal disease because it is very sensitive and widely available; however, MRI is also very useful in this context because its high tissue resolution and anatomic detail make it more specific. The morphologic findings and the characteristics of the contents of the <span class="hlt">tubes</span> on MRI enable a more accurate diagnosis or limit the differential diagnosis, helping to ensure that the most appropriate treatment is provided in each case. Copyright © 2012 SERAM. Published by Elsevier Espana. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22521997','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22521997"><span>MAGNETOHYDRODYNAMIC KINK WAVES IN NONUNIFORM SOLAR <span class="hlt">FLUX</span> <span class="hlt">TUBES</span>: PHASE MIXING AND ENERGY CASCADE TO SMALL SCALES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Soler, Roberto; Terradas, Jaume</p> <p>2015-04-10</p> <p>Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar atmosphere. The propagation and damping of these waves may play relevant roles in the transport and dissipation of energy in the solar atmospheric medium. However, in the atmospheric plasma dissipation of transverse MHD wave energy by viscosity or resistivity needs very small spatial scales to be efficient. Here, we theoretically investigate the generation of small scales in nonuniform solar <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> due to phase mixing of MHD kink waves. We go beyond the usual approach based on the existence of a global quasi-mode that is damped in time due to resonant absorption. Instead, we use a modal expansion to express the MHD kink wave as a superposition of Alfvén continuum modes that are phase mixed as time evolves. The comparison of the two techniques evidences that the modal analysis is more physically transparent and describes both the damping of global kink motions and the building up of small scales due to phase mixing. In addition, we discuss that the processes of resonant absorption and phase mixing are closely linked. They represent two aspects of the same underlying physical mechanism: the energy cascade from large scales to small scales due to naturally occurring plasma and/or <span class="hlt">magnetic</span> field inhomogeneities. This process may provide the necessary scenario for efficient dissipation of transverse MHD wave energy in the solar atmospheric plasma.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10133034','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10133034"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise in copper oxide superconductors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferrari, Mark Joseph</p> <p>1991-11-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise and <span class="hlt">flux</span> creep in thin films and single crystals of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>, Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x</sub>, Tl<sub>2</sub>Ca<sub>2</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>x</sub>, and TlCa<sub>2</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>x</sub> are measured with a superconducting quantum interference device (SQUID). The noise power spectrum generally scales as 1/f (f is frequency) from 1 Hz to 1 kHz, increases with temperature, and decreases in higher-quality films. It is proportional to the <span class="hlt">magnetic</span> field B in which the sample is cooled, at least in the range 0.1 mT < B < 3 mT. A model of thermally activated vortex motion is developed which explains the dependence of the noise on frequency, temperature, current, and applied <span class="hlt">magnetic</span> field. The pinning potential is idealized as an ensemble of double wells, each with a different activation energy separating the two states. From the noise measurements, this model yields the distribution of pinning energies in the samples, the vortex hopping distance, the number density of mobile vortices, and the restoring force on a vortex at a typical pinning site. The distribution of pinning energies in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> shows a broad peak below 0.1 eV. The small ambient <span class="hlt">magnetic</span> field, and the detection of noise even in the absence of a driving force, insure that the measured pinning energies are characteristic of isolated vortices near thermal equilibrium. The observed vortex density in fields much less than 0.1 mT is too large to be explained by the ambient field, suggesting a mechanism intrinsic to the sample which produces trapped vortices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5466714','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5466714"><span>Compressed <span class="hlt">magnetic</span> <span class="hlt">flux</span> amplifier with capacitive load</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stuetzer, O.M.</p> <p>1980-03-01</p> <p>A first-order analysis is presented for a compressed <span class="hlt">magnetic</span> <span class="hlt">flux</span> (CMF) current amplifier working into a load with a capacitive component. Since the purpose of the investigation was to gain a general understanding of the arrangement, a number of approximations and limitations were accepted. The inductance of the transducer varies with time; the inductance/resistance/capacitance (LRC) circuit therefore is parametric and solutions are different for the stable regime (high C), the oscillation regime (low C), and the transition case. Solutions and performance depend strongly on circuit boundary conditions, i.e., energization of the circuit by either an injected current or by an applied capacitor charge. The behavior of current and energy amplification for the various cases are discussed in detail. A number of experiments with small CMF devices showed that the first-order theory presented predicts transducer performance well in the linear regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6339953','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6339953"><span><span class="hlt">Magnetic</span> nerve stimulation without interlinkage between nerve and <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ueno, S.; Harada, K.; Ji, C.; Oomura, Y.</p> <p>1984-09-01</p> <p>A new method of <span class="hlt">magnetic</span> stimulation of nerves is proposed. Nerves are located on a core aperture outside the core which is implanted in the body. Nerves can be stimulated by the secondary currents which flow in the body fluids around the core when the <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the core is changed. One of the advantages in this method is to be able to avoid the interlinkage between the core and nerves. The equivalent resistance of tissues around the core is calculated, and current density for nerve excitation is estimated. The validity of the new method is demonstrated by experiments using frog nerve-muscle preparations. The results show that the nerve can be excited by a change of <span class="hlt">magnetic</span> <span class="hlt">flux</span> which generates an EMF of 0.8-volts peak amplitude and 0.8-ms duration in a monitor wire. The current density in the vicinity of the core aperture for nerve excitation is 3.2 mA/cm/sup 2/.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850046161&hterms=growing+old&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgrowing%2Bold','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850046161&hterms=growing+old&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgrowing%2Bold"><span>Relationships of a growing <span class="hlt">magnetic</span> <span class="hlt">flux</span> region to flares</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martin, S. F.; Bentley, R. D.; Schadee, A.; Antalova, A.; Kucera, A.; Dezso, L.; Gesztelyi, L.; Harvey, K. L.; Jones, H.; Livi, S. H. B.</p> <p>1984-01-01</p> <p>The evolution of flare sites at the boundaries of major new and growing <span class="hlt">magnetic</span> <span class="hlt">flux</span> regions within complexes of active regions has been analyzed using H-alpha images. A spectrum of possible relationships of growing <span class="hlt">flux</span> regions to flares is described. An 'intimate' interaction between old and new <span class="hlt">flux</span> and flare sites occurs at the boundaries of their regions. Forced or 'intimidated' interaction involves new <span class="hlt">flux</span> pushing older, lower <span class="hlt">flux</span> density fields toward a neighboring old polarity inversion line, followed by the occurrence of a flare. In 'influential' interaction, <span class="hlt">magnetic</span> lines of force over an old polarity inversion line reconnect to new emerging <span class="hlt">flux</span>, and a flare occurs when the <span class="hlt">magnetic</span> field overlying the filament becomes too weak to prevent its eruption. 'Inconsequential' interaction occurs when a new <span class="hlt">flux</span> region is too small or has the wrong orientation for creating flare conditions. 'Incidental' interaction involves a flare occurring without any significant relationship to new <span class="hlt">flux</span> regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850046161&hterms=intimate+relationships&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dintimate%2Brelationships','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850046161&hterms=intimate+relationships&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dintimate%2Brelationships"><span>Relationships of a growing <span class="hlt">magnetic</span> <span class="hlt">flux</span> region to flares</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martin, S. F.; Bentley, R. D.; Schadee, A.; Antalova, A.; Kucera, A.; Dezso, L.; Gesztelyi, L.; Harvey, K. L.; Jones, H.; Livi, S. H. B.</p> <p>1984-01-01</p> <p>The evolution of flare sites at the boundaries of major new and growing <span class="hlt">magnetic</span> <span class="hlt">flux</span> regions within complexes of active regions has been analyzed using H-alpha images. A spectrum of possible relationships of growing <span class="hlt">flux</span> regions to flares is described. An 'intimate' interaction between old and new <span class="hlt">flux</span> and flare sites occurs at the boundaries of their regions. Forced or 'intimidated' interaction involves new <span class="hlt">flux</span> pushing older, lower <span class="hlt">flux</span> density fields toward a neighboring old polarity inversion line, followed by the occurrence of a flare. In 'influential' interaction, <span class="hlt">magnetic</span> lines of force over an old polarity inversion line reconnect to new emerging <span class="hlt">flux</span>, and a flare occurs when the <span class="hlt">magnetic</span> field overlying the filament becomes too weak to prevent its eruption. 'Inconsequential' interaction occurs when a new <span class="hlt">flux</span> region is too small or has the wrong orientation for creating flare conditions. 'Incidental' interaction involves a flare occurring without any significant relationship to new <span class="hlt">flux</span> regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016htmp.book..707Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016htmp.book..707Z"><span>Study on Crystallization Properties of Mold <span class="hlt">Flux</span> in <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Congjing; Wang, Yu; Hu, Lang; Zhu, Mingmei; Wang, Hongpo</p> <p></p> <p><span class="hlt">Magnetic</span> field has a great effect on the crystallization behavior of mold <span class="hlt">flux</span> and properties of the <span class="hlt">flux</span> film between mold and strand, on which the surface quality of strand was deeply depended in continuous casting process. Therefore, studying the change law of the crystallization properties of mold <span class="hlt">flux</span> in <span class="hlt">magnetic</span> field is of great significant. In the present work, based on intensity of the applied <span class="hlt">magnetic</span> field with the range from 0mT to 60mT, the crystallization ratio, crystal size and mineralogical phases of the <span class="hlt">flux</span> film were discussed. The results show that crystallization ratio increases with the increasing <span class="hlt">magnetic</span> field intensity, and the crystal size becomes bigger at the same time. The <span class="hlt">magnetic</span> field promotes the crystallization ratio and growth speed of the crystallized grains of mold <span class="hlt">flux</span>. However, <span class="hlt">magnetic</span> field doesn't change types of the mineralogical phases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997NuPhA.619..321L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NuPhA.619..321L"><span>Dynamical fragmentation of <span class="hlt">flux</span> <span class="hlt">tubes</span> in the Friedberg-Lee model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loh, S.; Greiner, C.; Mosel, U.; Thoma, M. H.</p> <p>1997-02-01</p> <p>We present two novel dynamical features of <span class="hlt">flux</span> <span class="hlt">tubes</span> in the Friedberg-Lee model. First the fusion of two (anti-)parallel <span class="hlt">flux</span> <span class="hlt">tubes</span>, where we extract a string-string interaction potential which has a qualitative similarity to the nucleon-nucleon potential in the Friedberg-Lee model obtained by Koepf et al. Furthermore we show the dynamical breakup of <span class="hlt">flux</span> <span class="hlt">tubes</span> via q overlineq- particle production and the disintegration into mesons. We find, as a shortcoming of the present realization of the model, that the full dynamical transport approach presented in a previous publication fails to provide the disintegration mechanism in the semiclassical limit. Therefore, in addition, we present here a molecular dynamical approach for the motion of the quarks and show, as a first application, the space-time development of the wuarks and their mean-fields for Lund-type string fragmentation processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhRvB..78b4510A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhRvB..78b4510A"><span><span class="hlt">Flux</span> <span class="hlt">tubes</span> and the type-I/type-II transition in a superconductor coupled to a superfluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alford, Mark G.; Good, Gerald</p> <p>2008-07-01</p> <p>We analyze <span class="hlt">magnetic-flux</span> <span class="hlt">tubes</span> at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient (“entrainment”) interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is general and simple, modeling the interactions as a Ginzburg-Landau effective theory with four-fermion couplings, including only s -wave pairing. We numerically solve the field equations for <span class="hlt">flux</span> <span class="hlt">tubes</span> with an arbitrary number of <span class="hlt">flux</span> quanta and compare their energies. This allows us to map the type-I/type-II transition in the superconductor, which occurs at the conventional κ≡λ/ξ=1/2 if the condensates are uncoupled. We find that a density coupling between the condensates raises the critical κ and, for a sufficiently high neutron density, resolves the type-I/type-II transition line into an infinite number of bands corresponding to “ type-II(n) ” phases, in which n , the number of quanta in the favored <span class="hlt">flux</span> <span class="hlt">tube</span>, steps from 1 to infinity. For lower neutron density, the coupling creates spinodal regions around the type-I/type-II boundary, in which metastable <span class="hlt">flux</span> configurations are possible. We find that a gradient coupling between the condensates lowers the critical κ and creates spinodal regions. These exotic phenomena may not occur in nuclear matter, which is thought to be deep in the type-II region but might be observed in condensed-matter systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21143589','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21143589"><span><span class="hlt">Flux</span> <span class="hlt">tubes</span> and the type-I/type-II transition in a superconductor coupled to a superfluid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alford, Mark G.; Good, Gerald</p> <p>2008-07-01</p> <p>We analyze <span class="hlt">magnetic-flux</span> <span class="hlt">tubes</span> at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient ('entrainment') interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is general and simple, modeling the interactions as a Ginzburg-Landau effective theory with four-fermion couplings, including only s-wave pairing. We numerically solve the field equations for <span class="hlt">flux</span> <span class="hlt">tubes</span> with an arbitrary number of <span class="hlt">flux</span> quanta and compare their energies. This allows us to map the type-I/type-II transition in the superconductor, which occurs at the conventional {kappa}{identical_to}{lambda}/{xi}=1/{radical}(2) if the condensates are uncoupled. We find that a density coupling between the condensates raises the critical {kappa} and, for a sufficiently high neutron density, resolves the type-I/type-II transition line into an infinite number of bands corresponding to 'type-II(n)' phases, in which n, the number of quanta in the favored <span class="hlt">flux</span> <span class="hlt">tube</span>, steps from 1 to infinity. For lower neutron density, the coupling creates spinodal regions around the type-I/type-II boundary, in which metastable <span class="hlt">flux</span> configurations are possible. We find that a gradient coupling between the condensates lowers the critical {kappa} and creates spinodal regions. These exotic phenomena may not occur in nuclear matter, which is thought to be deep in the type-II region but might be observed in condensed-matter systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22357168','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22357168"><span>Complexity and diffusion of <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces in anisotropic turbulence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Servidio, S.; Matthaeus, W. H.; Wan, M.; Rappazzo, A. F.; Ruffolo, D.; Oughton, S.</p> <p>2014-04-10</p> <p>The complexity of <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces is investigated analytically and numerically in static homogeneous <span class="hlt">magnetic</span> turbulence. <span class="hlt">Magnetic</span> surfaces are computed to large distances in <span class="hlt">magnetic</span> fields derived from a reduced magnetohydrodynamic model. The question addressed is whether one can define <span class="hlt">magnetic</span> surfaces over large distances when turbulence is present. Using a <span class="hlt">flux</span> surface spectral analysis, we show that <span class="hlt">magnetic</span> surfaces become complex at small scales, experiencing an exponential thinning that is quantified here. The computation of a <span class="hlt">flux</span> surface is of either exponential or nondeterministic polynomial complexity, which has the conceptual implication that global identification of <span class="hlt">magnetic</span> <span class="hlt">flux</span> surfaces and <span class="hlt">flux</span> exchange, e.g., in <span class="hlt">magnetic</span> reconnection, can be intractable in three dimensions. The coarse-grained large-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> experiences diffusive behavior. The link between the diffusion of the coarse-grained <span class="hlt">flux</span> and field-line random walk is established explicitly through multiple scale analysis. The Kubo number controls both large and small scale limits. These results have consequences for interpreting processes such as <span class="hlt">magnetic</span> reconnection and field-line diffusion in astrophysical plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...836...46B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...836...46B"><span>Hall Effect-Mediated <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Transport in Protoplanetary Disks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bai, Xue-Ning; Stone, James M.</p> <p>2017-02-01</p> <p>The global evolution of protoplanetary disks (PPDs) has recently been shown to be largely controlled by the amount of poloidal <span class="hlt">magnetic</span> <span class="hlt">flux</span> threading the disk. The amount of <span class="hlt">magnetic</span> <span class="hlt">flux</span> must also coevolve with the disk, as a result of <span class="hlt">magnetic</span> <span class="hlt">flux</span> transport, a process that is poorly understood. In weakly ionized gas as in PPDs, <span class="hlt">magnetic</span> <span class="hlt">flux</span> is largely frozen in the electron fluid, except when resistivity is large. When the disk is largely laminar, we show that the relative drift between the electrons and ions (the Hall drift), and the ions and neutral fluids (ambipolar drift) can play a dominant role on the transport of <span class="hlt">magnetic</span> <span class="hlt">flux</span>. Using two-dimensional simulations that incorporate the Hall effect and ambipolar diffusion (AD) with prescribed diffusivities, we show that when large-scale poloidal field is aligned with disk rotation, the Hall effect rapidly drags <span class="hlt">magnetic</span> <span class="hlt">flux</span> inward at the midplane region, while it slowly pushes <span class="hlt">flux</span> outward above/below the midplane. This leads to a highly radially elongated field configuration as a global manifestation of the Hall-shear instability. This field configuration further promotes rapid outward <span class="hlt">flux</span> transport by AD at the midplane, leading to instability saturation. In quasi-steady state, <span class="hlt">magnetic</span> <span class="hlt">flux</span> is transported outward at approximately the same rate at all heights, and the rate is comparable to the Hall-free case. For anti-aligned field polarity, the Hall effect consistently transports <span class="hlt">magnetic</span> <span class="hlt">flux</span> outward, leading to a largely vertical field configuration in the midplane region. The field lines in the upper layer first bend radially inward and then outward to launch a disk wind. Overall, the net rate of outward <span class="hlt">flux</span> transport is about twice as fast as that of the aligned case. In addition, the rate of <span class="hlt">flux</span> transport increases with increasing disk <span class="hlt">magnetization</span>. The absolute rate of transport is sensitive to disk microphysics, which remains to be explored in future studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21300560','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21300560"><span>MULTIPLE SCATTERING OF WAVES BY A PAIR OF GRAVITATIONALLY STRATIFIED <span class="hlt">FLUX</span> <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hanasoge, Shravan M.; Cally, Paul S.</p> <p>2009-05-20</p> <p>We study the near-field coupling of a pair of <span class="hlt">flux</span> <span class="hlt">tubes</span> embedded in a gravitationally stratified environment. The mutual induction of the near-field jackets of the two <span class="hlt">flux</span> <span class="hlt">tubes</span> can considerably alter the scattering properties of the system, resulting in sizable changes in the magnitudes of scattering coefficients and bizarre trends in the phases. The dominant length scale governing the induction zone turns out to be approximately half the horizontal wavelength of the incident mode, a result that fits in quite pleasantly with extant theories of scattering. Higher-{beta} <span class="hlt">flux</span> <span class="hlt">tubes</span> are more strongly coupled than weaker ones, a consequence of the greater role that the near-field jacket modes play in such <span class="hlt">tubes</span>. We also comment on the importance of incorporating the effects of multiple scattering when studying the effects of mode absorption in plage and interpreting related scattering measurements. That the near field plays such an important role in the scattering process lends encouragement to the eventual goal of observationally resolving subwavelength features of <span class="hlt">flux</span> <span class="hlt">tubes</span> using techniques of helioseismology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JMMM..323.1611T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JMMM..323.1611T"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> distribution in the amorphous modular transformers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tomczuk, B.; Koteras, D.</p> <p>2011-06-01</p> <p>3D <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> in one-phase and three-phase transformers with amorphous modular cores have been studied. Scalar potentials were implemented for the 3D Finite Element field calculation. Due to the inability to simulate each thin amorphous layer, we introduced supplementary permeabilities along the main directions of <span class="hlt">magnetization</span>. The calculated <span class="hlt">fluxes</span> in the cores were tested on the prototypes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015A%26A...580A..57R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...580A..57R"><span>Standing kink oscillations of thin twisted <span class="hlt">magnetic</span> <span class="hlt">tubes</span> with continuous equilibrium <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruderman, M. S.; Terradas, J.</p> <p>2015-08-01</p> <p>In this article we study standing kink waves in twisted <span class="hlt">magnetic</span> <span class="hlt">tubes</span>. We use the cold plasma and thin <span class="hlt">tube</span> approximation. We assume that the plasma density is constant inside and outside the <span class="hlt">tube</span>. We also assume that the <span class="hlt">magnetic</span> twist is weak and take the ratio of the azimuthal and axial component of the <span class="hlt">magnetic</span> field to be of the order of ratio of the <span class="hlt">tube</span> radius and <span class="hlt">tube</span> length. The azimuthal component of the <span class="hlt">magnetic</span> field is proportional to the distance from the <span class="hlt">tube</span> axis inside the <span class="hlt">tube</span>, and inversely proportional to this distance outside the <span class="hlt">tube</span>. Using the method of asymptotic expansions we derived the governing integral equation that determines the eigenfrequencies and eigenmodes of the <span class="hlt">tube</span> kink oscillations. In the approximation of a very weak twist, we calculated analytically the corrections to the frequencies of the fundamental mode and first overtone of a straight <span class="hlt">magnetic</span> <span class="hlt">tube</span> related to the presence of twist. The analytical results are compared with the numerical results obtained using the full set of linear ideal magnetohydrodynamic equations. We also calculated the ratio of frequencies of the fist overtone and fundamental mode. We found that the <span class="hlt">magnetic</span> twist enhances this ratio for moderate values of the density ratio, and reduces this ratio for large values of the density ratio. In general, the deviation of the frequency ratio from 2 caused by the <span class="hlt">magnetic</span> twist is comparable to that found in simultaneous observations of the fundamental mode and first overtone of the coronal loop kink oscillations. Finally, we studied the eigenmode polarization. We found that, in a particular case of linear polarization, the polarization direction rotates along the <span class="hlt">tube</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000APS..DPPUP1083H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000APS..DPPUP1083H"><span>Compact Toroid Propagation in a <span class="hlt">Magnetized</span> Drift <span class="hlt">Tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horton, Robert D.; Baker, Kevin L.; Hwang, David Q.; Evans, Russell W.</p> <p>2000-10-01</p> <p>Injection of a spheromak-like compact toroid (SCT) plasma into a toroidal plasma confinement device may require the SCT to propagate through a drift <span class="hlt">tube</span> region occupied by a pre-existing <span class="hlt">magnetic</span> field. This field is expected to extert a retarding force on the SCT, but may also result in a beneficial compression. The effects of transverse and longitudinal <span class="hlt">magnetic</span> fields will be measured using the CTIX compact-toroid injector, together with a fast framing camera with an axial view of the formation, coaxial, and drift-<span class="hlt">tube</span> regions. In the case of longitudinal <span class="hlt">magnetic</span> field, comparisons will be made with the predictions of two-dimensional numerical simulation. The use of localized <span class="hlt">magnetic</span> field to reduce plasma bridging of the insulating gap will also be investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhFl...18i3601L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhFl...18i3601L"><span>Measurements and computations of mass flow and momentum <span class="hlt">flux</span> through short <span class="hlt">tubes</span> in rarefied gases</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lilly, T. C.; Gimelshein, S. F.; Ketsdever, A. D.; Markelov, G. N.</p> <p>2006-09-01</p> <p>Gas flows through orifices and short <span class="hlt">tubes</span> have been extensively studied from the 1960s through the 1980s for both fundamental and practical reasons. These flows are a basic and often important element of various modern gas driven instruments. Recent advances in micro- and nanoscale technologies have paved the way for a generation of miniaturized devices in various application areas, from clinical analyses to biochemical detection to aerospace propulsion. The latter is the main area of interest of this study, where rarefied gas flow into a vacuum through short <span class="hlt">tubes</span> with thickness-to-diameter ratios varying from 0.015 to 1.2 is investigated both experimentally and numerically with kinetic and continuum approaches. Helium and nitrogen gases are used in the range of Reynolds numbers from 0.02 to 770 (based on the <span class="hlt">tube</span> diameter), corresponding to Knudsen numbers from 40 down to about 0.001. Propulsion properties of relatively thin and thick <span class="hlt">tubes</span> are examined. Good agreement between experimental and numerical results is observed for mass flow rate and momentum <span class="hlt">flux</span>, the latter being corrected for the experimental facility background pressure. For thick-to-thin <span class="hlt">tube</span> ratios of mass flow and momentum <span class="hlt">flux</span> versus pressure, a minimum is observed at a Knudsen number of about 0.5. A short <span class="hlt">tube</span> propulsion efficiency is shown to be much higher than that of a thin orifice. The effect of surface specularity on a thicker <span class="hlt">tube</span> specific impulse was found to be relatively small.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22127147','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22127147"><span>UBIQUITOUS SOLAR ERUPTIONS DRIVEN BY <span class="hlt">MAGNETIZED</span> VORTEX <span class="hlt">TUBES</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kitiashvili, I. N.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A.</p> <p>2013-06-10</p> <p>The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruption events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous <span class="hlt">magnetized</span> vortex <span class="hlt">tubes</span> generated by the Sun's turbulent convection in subsurface layers. The swirling vortex <span class="hlt">tubes</span> (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background <span class="hlt">magnetic</span> field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns and thermodynamic and <span class="hlt">magnetic</span> structure in the erupting vortex <span class="hlt">tubes</span>. The main new results are: (1) the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers; (2) the fluctuations in the vortex <span class="hlt">tubes</span> penetrating into the chromosphere are quasi-periodic with a characteristic period of 2-5 minutes; and (3) the eruptions are highly non-uniform: the flows are predominantly downward in the vortex <span class="hlt">tube</span> cores and upward in their surroundings; the plasma density and temperature vary significantly across the eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22518731','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22518731"><span>ERUPTING FILAMENTS WITH LARGE ENCLOSING <span class="hlt">FLUX</span> <span class="hlt">TUBES</span> AS SOURCES OF HIGH-MASS THREE-PART CMEs, AND ERUPTING FILAMENTS IN THE ABSENCE OF ENCLOSING <span class="hlt">FLUX</span> <span class="hlt">TUBES</span> AS SOURCES OF LOW-MASS UNSTRUCTURED CMEs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hutton, Joe; Morgan, Huw</p> <p>2015-11-01</p> <p>The 3-part appearance of many coronal mass ejections (CMEs) arising from erupting filaments emerges from a large <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> structure, consistent with the form of the erupting filament system. Other CMEs arising from erupting filaments lack a clear 3-part structure and reasons for this have not been researched in detail. This paper aims to further establish the link between CME structure and the structure of the erupting filament system and to investigate whether CMEs which lack a 3-part structure have different eruption characteristics. A survey is made of 221 near-limb filament eruptions observed from 2013 May 03 to 2014 June 30 by Extreme UltraViolet (EUV) imagers and coronagraphs. Ninety-two filament eruptions are associated with 3-part structured CMEs, 41 eruptions are associated with unstructured CMEs. The remaining 88 are categorized as failed eruptions. For 34% of the 3-part CMEs, processing applied to EUV images reveals the erupting front edge is a pre-existing loop structure surrounding the filament, which subsequently erupts with the filament to form the leading bright front edge of the CME. This connection is confirmed by a <span class="hlt">flux</span>-rope density model. Furthermore, the unstructured CMEs have a narrower distribution of mass compared to structured CMEs, with total mass comparable to the mass of 3-part CME cores. This study supports the interpretation of 3-part CME leading fronts as the outer boundaries of a large pre-existing <span class="hlt">flux</span> <span class="hlt">tube</span>. Unstructured (non 3-part) CMEs are a different family to structured CMEs, arising from the eruption of filaments which are compact <span class="hlt">flux</span> <span class="hlt">tubes</span> in the absence of a large system of enclosing closed field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22092271','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22092271"><span>PROTOSTELLAR ACCRETION FLOWS DESTABILIZED BY <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> REDISTRIBUTION</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Krasnopolsky, Ruben; Shang, Hsien; Li Zhiyun; Zhao Bo</p> <p>2012-09-20</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> redistribution lies at the heart of the problem of star formation in dense cores of molecular clouds that are <span class="hlt">magnetized</span> to a realistic level. If all of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> of a typical core were to be dragged into the central star, the stellar field strength would be orders of magnitude higher than the observed values. This well-known <span class="hlt">magnetic</span> <span class="hlt">flux</span> problem can in principle be resolved through non-ideal MHD effects. Two-dimensional (axisymmetric) calculations have shown that ambipolar diffusion, in particular, can transport <span class="hlt">magnetic</span> <span class="hlt">flux</span> outward relative to matter, allowing material to enter the central object without dragging the field lines along. We show through simulations that such axisymmetric protostellar accretion flows are unstable in three dimensions to <span class="hlt">magnetic</span> interchange instability in the azimuthal direction. The instability is driven by the <span class="hlt">magnetic</span> <span class="hlt">flux</span> redistributed from the matter that enters the central object. It typically starts to develop during the transition from the prestellar phase of star formation to the protostellar mass accretion phase. In the latter phase, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> is transported outward mainly through advection by strongly <span class="hlt">magnetized</span> low-density regions that expand against the collapsing inflow. The tussle between the gravity-driven infall and <span class="hlt">magnetically</span> driven expansion leads to a highly filamentary inner accretion flow that is more disordered than previously envisioned. The efficient outward transport of <span class="hlt">magnetic</span> <span class="hlt">flux</span> by advection lowers the field strength at small radii, making the <span class="hlt">magnetic</span> braking less efficient and the formation of rotationally supported disks easier in principle. However, we find no evidence for such disks in any of our rotating collapse simulations. We conclude that the inner protostellar accretion flow is shaped to a large extent by the <span class="hlt">flux</span> redistribution-driven <span class="hlt">magnetic</span> interchange instability. How disks form in such an environment is unclear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21432203','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21432203"><span>Nonlinear propagating kink waves in thin <span class="hlt">magnetic</span> <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ruderman, M. S.; Goossens, M.; Andries, J.</p> <p>2010-08-15</p> <p>The propagation of nonlinear nonaxisymmetric waves along a <span class="hlt">magnetic</span> <span class="hlt">tube</span> in an incompressible plasma embedded in a <span class="hlt">magnetic</span>-free plasma is studied. The plasma and <span class="hlt">magnetic</span> parameters in the <span class="hlt">tube</span> core as well as plasma parameters in the external plasma are constant. Between the <span class="hlt">tube</span> core and the <span class="hlt">magnetic</span>-free plasma there is a thin annulus where the Alfven speed monotonically decreases to zero. In this annulus there is a cylindrical surface where the phase speed of the global wave matches the local Alfven speed. In the vicinity of this surface there is an efficient conversion of the global wave energy in the energy of local Alfven waves. This results in the resonant absorption of the global wave and, as a consequence, in the global wave damping. The wave amplitude is assumed to be small and used as a small parameter in the singular perturbation method that is used to derive the nonlinear governing equation for nonaxisymmetric waves. This equation accounts both for nonlinearity and wave damping due to resonant absorption. A particular class of solutions of this equation in the form of helical waves is studied numerically. The main result obtained in this study is that nonlinearity accelerates the wave damping. It also distorts the shape of the <span class="hlt">tube</span> boundary due to nonlinear generation of fluting modes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM51D..06T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM51D..06T"><span>Comparisons of Earthward Poynting <span class="hlt">flux</span> and the kinetic energy <span class="hlt">flux</span> of up-flowing transversely heated ions from the Polar spacecraft on cusp <span class="hlt">magnetic</span> field lines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tian, S.; Wygant, J. R.; Cattell, C. A.; Scudder, J. D.; Mozer, F.; Russell, C. T.</p> <p>2013-12-01</p> <p>This paper presents estimates of the Poynting <span class="hlt">flux</span> flowing along <span class="hlt">magnetic</span> field lines in the Earth's cusp region over altitudes from 0.8 Re to 7 Re using measurements during several passes from the Polar spacecraft. The Poynting <span class="hlt">flux</span> is calculated from measurements of electric fields from the University of California, Berkeley double probe electric field instrument, and from <span class="hlt">magnetic</span> field measurements from the U.C.L.A. fluxgate magnetometer. The estimates of Poynting <span class="hlt">flux</span> are of special interest because the high altitude mapping of the cusp <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> may connect to newly reconnected field lines and the low altitude mapping of these field lines is the scene of powerful acceleration processes, most notably transverse heating and outflow of ions. The data show that the Poynting <span class="hlt">flux</span> is predominantly downward over the frequency range from 1 mHz to 1 Hz . This frequency range includes the Poynting <span class="hlt">flux</span> due to steady state convection and field-aligned current systems, Alfven waves, and kinetic Alfven waves. Measurement of transversely heated ions over the energy ranges from 10 eV to several keV and their associated ion kinetic energy <span class="hlt">flux</span> are presented from the University of Iowa Hydra instrument and compared to the values of the downward Poynting <span class="hlt">flux</span>. Generally the downward Poynting <span class="hlt">flux</span> exceeds the upward kinetic energy <span class="hlt">flux</span> of the ions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvD..87h6001F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvD..87h6001F"><span>Shifted orbifold models with <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujimoto, Yukihiro; Kobayashi, Tatsuo; Miura, Takashi; Nishiwaki, Kenji; Sakamoto, Makoto</p> <p>2013-04-01</p> <p>We propose a mechanism to obtain the generation of matter in the standard model. We start from the analysis of the T2/ZN shifted orbifold with <span class="hlt">magnetic</span> <span class="hlt">flux</span>, which imposes a ZN symmetry on torus. We also consider several orbifolds such as (T2×T2)/ZN, (T2×T2×T2)/(ZN×ZN') and (T2×T2×T2)/(ZN×ZN'×ZN''). On such orbifolds, we study the behavior of fermions in two different means—the operator formalism and the explicit analysis of wave functions. For an interesting result, it is found that the number of zero-mode fermions is related to N of the ZN symmetry. In other words, the generation of matter relates to the type of orbifolds. Moreover, we find that shifted orbifold models are severely restricted from realizing three generations. For example, the three-generation model on the type of M4×(T2×T2)/ZN is unique. One can also construct other types of three-generation orbifold models with rich flavor structure. Those results may bring us a realistic model with desired Yukawa structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007277','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007277"><span><span class="hlt">Flux</span> Transport and the Sun's Global <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, David H.</p> <p>2010-01-01</p> <p>The Sun s global <span class="hlt">magnetic</span> field is produced and evolved through the emergence of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in active regions and its transport across the solar surface by the axisymmetric differential rotation and meridional flow and the non-axisymmetric convective flows of granulation, supergranulation, and giant cell convection. Maps of the global <span class="hlt">magnetic</span> field serve as the inner boundary condition for space weather. The photospheric <span class="hlt">magnetic</span> field and its evolution determine the coronal and solar wind structures through which CMEs must propagate and in which solar energetic particles are accelerated and propagate. Producing <span class="hlt">magnetic</span> maps which best represent the actual field configuration at any instant requires knowing the <span class="hlt">magnetic</span> field over the observed hemisphere as well as knowing the flows that transport <span class="hlt">flux</span>. From our Earth-based vantage point we only observe the front-side hemisphere and each pole is observable for only six months of the year at best. Models for the surface <span class="hlt">magnetic</span> <span class="hlt">flux</span> transport can be used to provide updates to the <span class="hlt">magnetic</span> field configuration in those unseen regions. In this presentation I will describe successes and failures of surface <span class="hlt">flux</span> transport and present new observations on the structure, the solar cycle variability, and the evolution of the flows involved in <span class="hlt">magnetic</span> <span class="hlt">flux</span> transport. I find that supergranules play the dominant role due to their strong flow velocities and long lifetimes. <span class="hlt">Flux</span> is transported by differential rotation and meridional flow only to the extent that the supergranules participate in those two flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......158G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......158G"><span>From QCD <span class="hlt">Flux</span> <span class="hlt">Tubes</span> to Gravitational S-matrix and Back</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gorbenko, Victor</p> <p></p> <p>We study the effective field theory of long relativistic strings such as confining <span class="hlt">flux</span> <span class="hlt">tubes</span> in QCD. Our main focus is on the scattering matrix of massless exci- tations propagating on the string’s worldsheet. The Lorentz invariance of QCD manifests itself in certain soft theorems satisfied by the amplitudes. We find that critical dimension appears as a condition that allows this scattering to be inte- grable and consequently <span class="hlt">flux</span> <span class="hlt">tubes</span> in four-dimensional QCD do not fall into this category. In case of the critical dimension equal to 26, however, we are able to find a full integrable S-matrix that exhibits many features expected from gravi- tational models. Moreover, it gives rise to a family of not necessarily integrable two-dimensional theories that inherit very peculiar UV-properties. We discuss im- plication of this construction for the hierarchy problem. We then return to the QCD <span class="hlt">flux</span> <span class="hlt">tubes</span> and find that integrability-inspired techniques can be applied to them in an approximate way that allows us to calculate their spectrum in the regime inaccessible for standard perturbation theory. In particular, analysis of the lattice data allows us to identify the first massive particle present on the world sheet of the QCD <span class="hlt">flux</span> <span class="hlt">tube</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950025450&hterms=rust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950025450&hterms=rust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Drust"><span>Helicity charging and eruption of <span class="hlt">magnetic</span> <span class="hlt">flux</span> from the Sun</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rust, David M.; Kumar, A.</p> <p>1994-01-01</p> <p>The ejection of helical toroidal fields from the solar atmosphere and their detection in interplanetary space are described. The discovery that solar <span class="hlt">magnetic</span> fields are twisted and that they are segregated by hemisphere according to their chirality has important implications for the escape process. The roles played by erupting prominences, coronal mass ejections (CME's) and active region (AR) loops in expressing the escape of <span class="hlt">magnetic</span> <span class="hlt">flux</span> and helicity are discussed. Sporadic <span class="hlt">flux</span> escape associated with filament eruptions accounts for less than one-tenth the <span class="hlt">flux</span> loss. Azimuthal <span class="hlt">flux</span> loss by CME's could account for more, but the major contributor to <span class="hlt">flux</span> escape may be AR loop expansion. It is shown how the transfer of <span class="hlt">magnetic</span> helicity from the sun's interior into emerged loops ('helicity charging') could be the effective driver of solar eruptions and of <span class="hlt">flux</span> loss from the sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPTO8009R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPTO8009R"><span><span class="hlt">Flux</span>-limitation of the Nernst effect in <span class="hlt">magnetized</span> ICF</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ridgers, Christopher; Barrois, Rion; Wengraf, Joshua; Bissell, John; Brodrick, Jonathan; Kingham, Robert; Read, Martin</p> <p>2016-10-01</p> <p><span class="hlt">Magnetized</span> ICF is a promising scheme which combines the advantages of <span class="hlt">magnetic</span> and inertial confinement fusion. In the relevant high-energy density plasmas <span class="hlt">magnetic</span> field evolution is often controlled by the Nernst effect where the <span class="hlt">magnetic</span> field advects with the electron heat flow. It is well known that non-local thermal transport necessitates a <span class="hlt">flux</span>-limiter on the heat flow. This suggests that a <span class="hlt">flux</span>-limiter should also be applied to the Nernst effect. We have shown that this is the case using Vlasov-Fokker-Planck simulations and that the <span class="hlt">flux</span>-limter is not the same as that required for the heat flow itself, for example when a NIF-relevant <span class="hlt">flux</span>-limiter of 0.15 is required to limit the heat flow a Nernst <span class="hlt">flux</span> limiter of 0.08 is required. We acknowledge support from EPSRC Grant No. EPM011372/1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21378275','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21378275"><span>OBSERVATIONS OF A SMALL INTERPLANETARY <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> ROPE ASSOCIATED WITH A <span class="hlt">MAGNETIC</span> RECONNECTION EXHAUST</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Feng, H. Q.; Wu, D. J.</p> <p>2009-11-10</p> <p>A small interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope prior to an X-line <span class="hlt">magnetic</span> reconnection exhaust was observed on 1998 March 25 at 1 AU. The X-line <span class="hlt">magnetic</span> reconnection exhaust has been identified and reported by Gosling et al. The duration of this small <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope is about 2 hr. We fitted the constant alpha force-free model to the observed <span class="hlt">magnetic</span> fields. The model fitting results show that the spacecraft crosses the <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope well away from the axis, with d {sub 0}/R {sub 0} being 0.76. The fitting results also show that its <span class="hlt">magnetic</span> configuration is a right-handed helical <span class="hlt">flux</span> rope, that the estimated field intensity at the axis is 16.3 nT, and that its diameter is 0.0190 AU. In addition, the axial direction of this rope is (theta = 6 deg., phi = 214 deg.), namely, this <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope is lying nearly in the ecliptic plane. According to the geometric relation of the small <span class="hlt">flux</span> rope and the reconnection exhaust, it is very possible that the small <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope has a larger scale initially and comes from the corona; its <span class="hlt">magnetic</span> fields are peeled off when moving from the Sun to the Earth and at last it reaches a small scale. Though <span class="hlt">magnetic</span> reconnection can produce a <span class="hlt">flux</span>-rope topology, in this case the X-line <span class="hlt">magnetic</span> reconnection is destroying rather than generating the small <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JAP....74.6293G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JAP....74.6293G"><span><span class="hlt">Flux</span> trapping in superconducting thin films in weak <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Geng, Q.; Goto, E.</p> <p>1993-11-01</p> <p><span class="hlt">Magnetic</span>-field distribution measurements over a patterned superconducting strip line sample were conducted using a superconducting quantum interference device pickup coil, showing that, in the range of 500 μG-50 mG of perpendicular <span class="hlt">magnetic</span> field B⊥,i, the superconducting films record previous <span class="hlt">magnetic</span> histories precisely. The <span class="hlt">magnetic</span>-field distribution with a field B⊥,i applied at all times is identical to one with no field applied at any time. A calculation based on the <span class="hlt">flux</span> trapping model explains these results indicating that all the <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> penetrate the superconducting thin films.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMMM..377..395S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMMM..377..395S"><span><span class="hlt">Magnetic</span> field effect on flow parameters of blood along with <span class="hlt">magnetic</span> particles in a cylindrical <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharma, Shashi; Singh, Uaday; Katiyar, V. K.</p> <p>2015-03-01</p> <p>In this paper, the effect of external uniform <span class="hlt">magnetic</span> field on flow parameters of both blood and <span class="hlt">magnetic</span> particles is reported through a mathematical model using magnetohydrodynamics (MHD) approach. The fluid is acted upon by a varying pressure gradient and an external uniform <span class="hlt">magnetic</span> field is applied perpendicular to the cylindrical <span class="hlt">tube</span>. The governing nonlinear partial differential equations were solved numerically and found that flow parameters are affected by the influence of <span class="hlt">magnetic</span> field. Further, artificial blood (75% water+25% Glycerol) along with iron oxide <span class="hlt">magnetic</span> particles were prepared and transported into a glass <span class="hlt">tube</span> with help of a peristaltic pump. The velocity of artificial blood along with <span class="hlt">magnetic</span> particles was experimentally measured at different <span class="hlt">magnetic</span> fields ranging from 100 to 600 mT. The model results show that the velocity of blood and <span class="hlt">magnetic</span> particles is appreciably reduced under the influence of <span class="hlt">magnetic</span> field, which is supported by our experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25231262','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25231262"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Density of Different Types of New Generation <span class="hlt">Magnetic</span> Attachment Systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Akin, Hakan</p> <p>2015-07-01</p> <p>The purpose of this study was to analyze the static <span class="hlt">magnetic</span> <span class="hlt">flux</span> density of different types of new generation laser-welded <span class="hlt">magnetic</span> attachments in the single position and the attractive position and to determine the effect of different corrosive environments on <span class="hlt">magnetic</span> <span class="hlt">flux</span> density. <span class="hlt">Magnetic</span> <span class="hlt">flux</span> densities of four <span class="hlt">magnetic</span> attachment systems (Hyper slim, Hicorex slim, Dyna, and Steco) were measured with a gaussmeter. Then <span class="hlt">magnetic</span> attachment systems were immersed in two different media, namely 1% lactic acid solution (pH 2.3), and 0.9% NaCl solution (pH 7.3). <span class="hlt">Magnetic</span> <span class="hlt">flux</span> densities of the attachment systems were measured with a gaussmeter after immersion to compare with measurements before immersion (α = 0.05). The data were statistically evaluated with one-way ANOVA, paired-samples t-test, and post hoc Tukey-Kramer multiple comparisons tests (α = 0.05). The highest <span class="hlt">magnetic</span> <span class="hlt">flux</span> density was found in Dyna <span class="hlt">magnets</span> for both single and attractive positions. In addition, after the <span class="hlt">magnets</span> were in the corrosive environments for 2 weeks, they had a significant decrease in <span class="hlt">magnetic</span> <span class="hlt">flux</span> density (p < 0.05). No significant differences were found between corrosive environments (p > 0.05). The leakage <span class="hlt">flux</span> of all the <span class="hlt">magnetic</span> attachments did not exceed the WHO's guideline of 40 mT. The <span class="hlt">magnets</span> exhibited a significant decrease in <span class="hlt">magnetic</span> <span class="hlt">flux</span> density after aging in corrosive environments including lactic acid and NaCl. © 2014 by the American College of Prosthodontists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPGO7001H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPGO7001H"><span>3D Laboratory Measurements of Forces, Flows, and Collimation in Arched <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haw, Magnus; Bellan, Paul</p> <p>2016-10-01</p> <p>Fully 3D, vector MHD force measurements from an arched, current carrying <span class="hlt">flux</span> <span class="hlt">tube</span> (<span class="hlt">flux</span> rope) are presented. The experiment consists of two arched plasma-filled <span class="hlt">flux</span> ropes each powered by a capacitor bank. The two loops are partially overlapped, as in a Venn diagram, and collide and reconnect during their evolution. B-field data is taken on the lower plasma arch using a 54 channel B-dot probe. 3D volumetric data is acquired by placing the probe at 2700 locations and taking 5 plasma shots at each location. The resulting data set gives high resolution (2cm, 10ns) volumetric B-field data with high reproducibility (deviation of 3% between shots). Taking the curl of the measured 3D B-field gives current densities (J) in good agreement with measured capacitor bank current. The JxB forces calculated from the data have a strong axial component at the base of the current channel and are shown to scale linearly with axial gradients in current density. Assuming force balance in the <span class="hlt">flux</span> <span class="hlt">tube</span> minor radius direction, we infer near-Alfvenic axial flows from the footpoint regions which are consistent with the measured axial forces. <span class="hlt">Flux</span> <span class="hlt">tube</span> collimation is observed in conjunction with these axial flows. These dynamic processes are relevant to the stability and dynamics of coronal loops. Supported provided by NSF, AFOSR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/111456','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/111456"><span>Correlation of critical heat <span class="hlt">flux</span> data for uniform <span class="hlt">tubes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jafri, T.; Dougherty, T.J.; Yang, B.W.</p> <p>1995-09-01</p> <p>A data base of more than 10,000 critical heat <span class="hlt">flux</span> (CHF) data points has been compiled and analyzed. Two regimes of CHF are observed which will be referred to as the high CHF regime and the low CHF regime. In the high CHF regime, for pressures less than 110 bar, CHF (q{sub c}) is a determined by local conditions and is adequately represented by q{sub c} = (1.2/D{sup 1/2}) exp[-{gamma}(GX{sub t}){sup 1/2}] where the parameter {gamma} is an increasing function of pressure only, X{sub t} the true mass fraction of steam, and all units are metric but the heat <span class="hlt">flux</span> is in MWm{sup -2}. A simple kinetic model has been developed to estimate X{sub t} as a function of G, X, X{sub i}, and X{sub O}, where X{sub i} is the inlet quality and X{sub O} represents the quality at the Onset of Significant Vaporization (OSV) which is estimated from the Saha-Zuber (S-Z) correlation. The model is based on a rate equation for vaporization suggested by, and consistent with, the S-Z correlation and contains no adjustable parameters. When X{sub i}<X{sub O} (both negative), X{sub t} is independent of X{sub i} and is a function of local variables only. For X{sub i}>X{sub O}, X{sub t} depends on X{sub i}, a nonlocal variable, and, in this case, CHF, although determined by local conditions, obeys a nonlocal correlation. This model appears to be satisfactory for pressures less than 110 bar, where the S-Z correlation is known to be reliable. Above 110 bar the method of calculating X{sub O}, and consequently X{sub t}, appears to fail, so this approach can not be applied to high pressure CHF data. Above 35 bar, the bulk of the available data lies in the high CHF regime while, at pressures less than 35 bar, almost all of the available data lie in the low CHF regime and appear to be nonlocal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD0287057','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD0287057"><span>DEVELOPMENT OF S-BAND LOW-NOISE PERIODIC PERMANENT <span class="hlt">MAGNETIC</span> TRAVELING-WAVE <span class="hlt">TUBE</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p></p> <p>MICROWAVE AMPLIFIERS, *TRAVELING WAVE <span class="hlt">TUBES</span>, ANODES, DESIGN, ELECTRON BEAMS, ELECTRON GUNS, FOCUSING , HELIXES, IMPEDANCE MATCHING, <span class="hlt">MAGNETIC</span> FIELDS, <span class="hlt">MAGNETS</span>, NOISE (RADIO), REDUCTION, S BAND, STANDING WAVE RATIOS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21617374','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21617374"><span>Potassium <span class="hlt">flux</span> in the pollen <span class="hlt">tubes</span> was essential in plant sexual reproduction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Ju-You; Jin, Cong; Zhang, Shao-Ling</p> <p>2011-06-01</p> <p>Potassium channels are controlling K (+) transport across plasma membrane and thus playing a central role in all aspects of osmolarity as well as numerous other functions in plants including in sexual reproduction. We have used whole-cell and single-channel patch-clamp recording techniques investigated the regulation of intracellular free Ca ( 2+) -activated outward K (+) channels in Pyrus pyrifolia pollen <span class="hlt">tube</span> protoplasts. We have also showed the channels could be inhibited by heme and activated carbon monoxide (CO). In the presence of oxygen and NADPH, hemoxygenases catalyzes heme degradation, producing biliverdin, iron and CO. Considered the oxygen concentration approaching zero in the ovary, the heme will inhibit the K (+) outward <span class="hlt">flux</span> from the intracellular of pollen <span class="hlt">tube</span>, increasing the pollen <span class="hlt">tubes</span> osmolarity, inducing pollen <span class="hlt">tube</span> burst. Here we discuss the putative role of K (+) channels in plant sexual reproduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920048623&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drotation%2Bmagnetic%2Bflux','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920048623&hterms=rotation+magnetic+flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drotation%2Bmagnetic%2Bflux"><span>Coronal mass ejections and <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in interplanetary space</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gosling, J. T.</p> <p>1990-01-01</p> <p>Coronal mass ejections (CMEs) are formed in the solar corona by the ejection of material from closed field regions that were not previously participating in the solar wind expansion. CMEs commonly exhibit a signature consisting of a counterstreaming <span class="hlt">flux</span> of suprathermal electrons with energies above about 80 eV, indicating closed field structures that are either rooted at both ends in the sun or entirely disconnected from it. About 30 percent of all CME events at 1 AU exhibit large, coherent internal field rotations typical of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. It is suggested that interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes form as a result of reconnection within rising, previously sheared coronal <span class="hlt">magnetic</span> loops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991JATP...53.1073A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991JATP...53.1073A"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> rope type structures in the geomagnetic tail</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Antonova, A. E.; Kropotkin, A. P.</p> <p>1991-12-01</p> <p>Some structures in the geomagnetic tail observed by the Prognoz 9 and ISEE spacecraft as '<span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes' are identified, and new features are emphasized. The structures are associated with considerable <span class="hlt">fluxes</span> of energetic ions and electrons. Particles are effectively energized at <span class="hlt">magnetic</span> field discontinuities, resulting in the generation of spectra extending up to MeV energies. An external field source (i.e., the interplanetary <span class="hlt">magnetic</span> field) may be of essential importance for the generation of the <span class="hlt">flux</span> ropes whose axes lie in the cross-tail direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22130892','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22130892"><span><span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> PARADIGM FOR RADIO LOUDNESS OF ACTIVE GALACTIC NUCLEI</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sikora, Marek; Begelman, Mitchell C. E-mail: mitch@jila.colorado.edu</p> <p>2013-02-20</p> <p>We argue that the <span class="hlt">magnetic</span> <span class="hlt">flux</span> threading the black hole (BH), rather than BH spin or Eddington ratio, is the dominant factor in launching powerful jets and thus determining the radio loudness of active galactic nuclei (AGNs). Most AGNs are radio quiet because the thin accretion disks that feed them are inefficient in depositing <span class="hlt">magnetic</span> <span class="hlt">flux</span> close to the BH. <span class="hlt">Flux</span> accumulation is more likely to occur during a hot accretion (or thick disk) phase, and we argue that radio-loud quasars and strong emission-line radio galaxies occur only when a massive, cold accretion event follows an episode of hot accretion. Such an event might be triggered by the merger of a giant elliptical galaxy with a disk galaxy. This picture supports the idea that <span class="hlt">flux</span> accumulation can lead to the formation of a so-called <span class="hlt">magnetically</span> choked accretion flow. The large observed range in radio loudness reflects not only the magnitude of the <span class="hlt">flux</span> pressed against the BH, but also the decrease in UV <span class="hlt">flux</span> from the disk, due to its disruption by the ''magnetosphere'' associated with the accumulated <span class="hlt">flux</span>. While the strongest jets result from the secular accumulation of <span class="hlt">flux</span>, moderate jet activity can also be triggered by fluctuations in the <span class="hlt">magnetic</span> <span class="hlt">flux</span> deposited by turbulent, hot inner regions of otherwise thin accretion disks, or by the dissipation of turbulent fields in accretion disk coronae. These processes could be responsible for jet production in Seyferts and low-luminosity AGNs, as well as jets associated with X-ray binaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPD....4840002Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPD....4840002Y"><span>MHD simulations of formation and eruption of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope in an active region with a delta-sunspot</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yokoyama, Takaaki; Oi, Yoshiaki; Toriumi, Shin</p> <p>2017-08-01</p> <p>Active regions holding a delta-sunspot are known to produce the largest class of solar flares. How, where, and when such large flares occur above a delta-sunspot are still under debate. For studying this, 3D MHD simulations of the emergence of a subsurface <span class="hlt">flux</span> <span class="hlt">tube</span> at two locations in a simulation box modeling the convection zone to the corona were conducted. We found that a <span class="hlt">flux</span> rope is formed as a consequence of <span class="hlt">magnetic</span> reconnection of two bipolar loops and sunspot rotation caused by the twist of the subsurface <span class="hlt">flux</span> <span class="hlt">tube</span>. Moreover, the <span class="hlt">flux</span> rope stops ascending when the initial background is not <span class="hlt">magnetized</span>, whereas it rises up to the upper boundary when a reconnection favorably oriented pre-existing field is introduced to the initial background.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SoPh..203..309H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SoPh..203..309H"><span>Catastrophe of Coronal <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes Caused by Photospheric Motions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Y. Q.; Jiang, Y. W.</p> <p>2001-11-01</p> <p>Using a 2.5-D, time-dependent ideal MHD model in Cartesian coordinates, we carried out numerical simulations to investigate the equilibrium and evolution properties of a <span class="hlt">magnetic</span> configuration that consists of a coronal <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope and a partly open photospheric background field, which is equivalent to that produced by a two-patch <span class="hlt">magnetic</span> source on the photospheric surface. The axial and annular <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> of the <span class="hlt">flux</span> rope are given and fixed. The global <span class="hlt">magnetic</span> configuration evolves in response to three types of changes of the background field: decreasing of the distance between the two sources, shrinking of the size of each source, and increasing of the shear in the closed component of the background field. As a result, the geometrical parameters of the <span class="hlt">flux</span> rope, i.e. the height of the rope axis, the half-width of the rope and the length of the vertical current sheet below the rope, change due to the variation of the background field. It is shown that for a given coronal <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope in a partly open background field, the variation of the geometrical parameters of the <span class="hlt">flux</span> rope displays a catastrophic behavior, namely, there exists a critical point for each case, at which an infinitesimal change of the background field leads to a loss of equilibrium, and thus a jump of the <span class="hlt">flux</span> rope. The implication of such a catastrophe in solar active phenomena is briefly discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22560329','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22560329"><span>Quantum transport in coupled resonators enclosed synthetic <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jin, L.</p> <p>2016-07-15</p> <p>Quantum transport properties are instrumental to understanding quantum coherent transport processes. Potential applications of quantum transport are widespread, in areas ranging from quantum information science to quantum engineering, and not restricted to quantum state transfer, control and manipulation. Here, we study light transport in a ring array of coupled resonators enclosed synthetic <span class="hlt">magnetic</span> <span class="hlt">flux</span>. The ring configuration, with an arbitrary number of resonators embedded, forms a two-arm Aharonov–Bohm interferometer. The influence of <span class="hlt">magnetic</span> <span class="hlt">flux</span> on light transport is investigated. Tuning the <span class="hlt">magnetic</span> <span class="hlt">flux</span> can lead to resonant transmission, while half-integer <span class="hlt">magnetic</span> <span class="hlt">flux</span> quantum leads to completely destructive interference and transmission zeros in an interferometer with two equal arms. -- Highlights: •The light transport is investigated through ring array of coupled resonators enclosed synthetic <span class="hlt">magnetic</span> field. •Aharonov–Bohm ring interferometer of arbitrary configuration is investigated. •The half-integer <span class="hlt">magnetic</span> <span class="hlt">flux</span> quantum leads to destructive interference and transmission zeros for two-arm at equal length. •Complete transmission is available via tuning synthetic <span class="hlt">magnetic</span> <span class="hlt">flux</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22494656','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22494656"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> studies in horizontally cooled elliptical superconducting cavities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martinello, M. Checchin, M.; Grassellino, A. Crawford, A. C.; Melnychuk, O.; Romanenko, A.; Sergatskov, D. A.</p> <p>2015-07-28</p> <p>Previous studies on <span class="hlt">magnetic</span> <span class="hlt">flux</span> expulsion as a function of cooldown procedures for elliptical superconducting radio frequency (SRF) niobium cavities showed that when the cavity beam axis is placed parallel to the helium cooling flow and sufficiently large thermal gradients are achieved, all <span class="hlt">magnetic</span> <span class="hlt">flux</span> could be expelled and very low residual resistance could be achieved. In this paper, we investigate <span class="hlt">flux</span> trapping for the case of resonators positioned perpendicularly to the helium cooling flow, which is more representative of how SRF cavities are cooled in accelerators and for different directions of the applied <span class="hlt">magnetic</span> field surrounding the resonator. We show that different field components have a different impact on the surface resistance, and several parameters have to be considered to fully understand the <span class="hlt">flux</span> dynamics. A newly discovered phenomenon of concentration of <span class="hlt">flux</span> lines at the cavity top leading to temperature rise at the cavity equator is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1213798-magnetic-flux-studies-horizontally-cooled-elliptical-superconducting-cavities','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1213798-magnetic-flux-studies-horizontally-cooled-elliptical-superconducting-cavities"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> studies in horizontally cooled elliptical superconducting cavities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Martinello, M.; Checchin, M.; Grassellino, A.; ...</p> <p>2015-07-29</p> <p>Previous studies on <span class="hlt">magnetic</span> <span class="hlt">flux</span> expulsion as a function of cooldown procedures for elliptical superconducting radio frequency (SRF) niobium cavities showed that when the cavity beam axis is placed parallel to the helium cooling flow and sufficiently large thermal gradients are achieved, all <span class="hlt">magnetic</span> <span class="hlt">flux</span> could be expelled and very low residual resistance could be achieved. In this paper, we investigate <span class="hlt">flux</span> trapping for the case of resonators positioned perpendicularly to the helium cooling flow, which is more representative of how SRF cavities are cooled in accelerators and for different directions of the applied <span class="hlt">magnetic</span> field surrounding the resonator. Wemore » show that different field components have a different impact on the surface resistance, and several parameters have to be considered to fully understand the <span class="hlt">flux</span> dynamics. A newly discovered phenomenon of concentration of <span class="hlt">flux</span> lines at the cavity top leading to temperature rise at the cavity equator is presented.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009odsm.book..175K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009odsm.book..175K"><span>Photospheric and Subphotospheric Dynamics of Emerging <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kosovichev, A. G.</p> <p></p> <p><span class="hlt">Magnetic</span> fields emerging from the Sun's interior carry information about physical processes of <span class="hlt">magnetic</span> field generation and transport in the convection zone. Soon after appearance on the solar surface the <span class="hlt">magnetic</span> <span class="hlt">flux</span> gets concentrated in sunspot regions and causes numerous active phenomena on the Sun. This paper discusses some properties of the emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> observed on the solar surface and in the interior. A statistical analysis of variations of the tilt angle of bipolar <span class="hlt">magnetic</span> regions during the emergence shows that the systematic tilt with respect to the equator (the Joy's law) is most likely established below the surface. However, no evidence of the dependence of the tilt angle on the amount of emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span>, predicted by the rising <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope theories, is found. Analysis of surface plasma flows in a large emerging active region reveals strong localized upflows and downflows at the initial phase of emergence but finds no evidence for large-scale flows indicating future appearance a large-scale <span class="hlt">magnetic</span> structure. Local helioseismology provides important tools for mapping perturbations of the wave speed and mass flows below the surface. Initial results from SOHO/MDI and GONG reveal strong diverging flows during the <span class="hlt">flux</span> emergence, and also localized converging flows around stable sunspots. The wave speed images obtained during the process of formation of a large active region, NOAA 10488, indicate that the <span class="hlt">magnetic</span> <span class="hlt">flux</span> gets concentrated in strong field structures just below the surface. Further studies of <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence require systematic helioseismic observations from the ground and space, and realistic MHD simulations of the subsurface dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009SSRv..144..175K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009SSRv..144..175K"><span>Photospheric and Subphotospheric Dynamics of Emerging <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kosovichev, A. G.</p> <p>2009-04-01</p> <p><span class="hlt">Magnetic</span> fields emerging from the Sun’s interior carry information about physical processes of <span class="hlt">magnetic</span> field generation and transport in the convection zone. Soon after appearance on the solar surface the <span class="hlt">magnetic</span> <span class="hlt">flux</span> gets concentrated in sunspot regions and causes numerous active phenomena on the Sun. This paper discusses some properties of the emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span> observed on the solar surface and in the interior. A statistical analysis of variations of the tilt angle of bipolar <span class="hlt">magnetic</span> regions during the emergence shows that the systematic tilt with respect to the equator (the Joy’s law) is most likely established below the surface. However, no evidence of the dependence of the tilt angle on the amount of emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span>, predicted by the rising <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope theories, is found. Analysis of surface plasma flows in a large emerging active region reveals strong localized upflows and downflows at the initial phase of emergence but finds no evidence for large-scale flows indicating future appearance a large-scale <span class="hlt">magnetic</span> structure. Local helioseismology provides important tools for mapping perturbations of the wave speed and mass flows below the surface. Initial results from SOHO/MDI and GONG reveal strong diverging flows during the <span class="hlt">flux</span> emergence, and also localized converging flows around stable sunspots. The wave speed images obtained during the process of formation of a large active region, NOAA 10488, indicate that the <span class="hlt">magnetic</span> <span class="hlt">flux</span> gets concentrated in strong field structures just below the surface. Further studies of <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence require systematic helioseismic observations from the ground and space, and realistic MHD simulations of the subsurface dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRA..112.2102F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRA..112.2102F"><span>Size and energy distributions of interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, H. Q.; Wu, D. J.; Chao, J. K.</p> <p>2007-02-01</p> <p>In observations from 1995 to 2001 from the Wind spacecraft, 144 interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes were identified in the solar wind around 1 AU. Their durations vary from tens of minutes to tens of hours. These <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes include many small- and intermediate-sized structures and display a continuous distribution in size. Energies of these <span class="hlt">flux</span> ropes are estimated and it is found that the distribution of their energies is a good power law spectrum with an index ~-0.87. The possible relationship between them and solar eruptions is discussed. It is suggested that like interplanetary <span class="hlt">magnetic</span> clouds are interplanetary coronal mass ejections, the small- and intermediate-sized interplanetary <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes are the interplanetary manifestations of small coronal mass ejections produced in small solar eruptions. However, these small coronal mass ejections are too weak to appear clearly in the coronagraph observations as an ordinary coronal mass ejection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AnPhy.370....1J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AnPhy.370....1J"><span>Quantum transport in coupled resonators enclosed synthetic <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, L.</p> <p>2016-07-01</p> <p>Quantum transport properties are instrumental to understanding quantum coherent transport processes. Potential applications of quantum transport are widespread, in areas ranging from quantum information science to quantum engineering, and not restricted to quantum state transfer, control and manipulation. Here, we study light transport in a ring array of coupled resonators enclosed synthetic <span class="hlt">magnetic</span> <span class="hlt">flux</span>. The ring configuration, with an arbitrary number of resonators embedded, forms a two-arm Aharonov-Bohm interferometer. The influence of <span class="hlt">magnetic</span> <span class="hlt">flux</span> on light transport is investigated. Tuning the <span class="hlt">magnetic</span> <span class="hlt">flux</span> can lead to resonant transmission, while half-integer <span class="hlt">magnetic</span> <span class="hlt">flux</span> quantum leads to completely destructive interference and transmission zeros in an interferometer with two equal arms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993ITAS....3.1804M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993ITAS....3.1804M"><span>Detection of <span class="hlt">magnetic</span> <span class="hlt">flux</span> with superconducting quantum interference gratings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, J. H., Jr.; Gunaratne, G. H.; Zou, Z.</p> <p>1993-03-01</p> <p>The authors have carried out finite-inductance calculations of the critical vs. <span class="hlt">flux</span> (Ic-Phi) and voltage vs. <span class="hlt">flux</span> (V-Phi) characteristics of superconducting interferometers with many Josephson junctions in parallel. At least two features of the calculations suggest that many junction interferometers, called superconducting quantum interference gratings, might be advantageous for the detection of <span class="hlt">magnetic</span> <span class="hlt">flux</span>. First, the voltage noise can be reduced significantly for a given <span class="hlt">flux</span>-to-voltage transfer coefficient, a feature which is likely to improve the <span class="hlt">magnetic</span> <span class="hlt">flux</span> sensitivity of both low- and high-Tc superconducting devices. In addition, nonuniformity of the junction critical currents appears to have little adverse effect on the predicted diffraction grating such as enhancement and narrowing of the peaks in the Ic-Phi characteristic. Specific schemes for efficiently coupling <span class="hlt">flux</span> into the device are proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013A%26A...554A..77P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013A%26A...554A..77P"><span>Magnetohydrodynamic simulations of the ejection of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pagano, P.; Mackay, D. H.; Poedts, S.</p> <p>2013-06-01</p> <p>Context. Coronal mass ejections (CME's) are one of the most violent phenomena found on the Sun. One model to explain their occurrence is the <span class="hlt">flux</span> rope ejection model. In this model, <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes form slowly over time periods of days to weeks. They then lose equilibrium and are ejected from the solar corona over a few hours. The contrasting time scales of formation and ejection pose a serious problem for numerical simulations. Aims: We simulate the whole life span of a <span class="hlt">flux</span> rope from slow formation to rapid ejection and investigate whether <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes formed from a continuous <span class="hlt">magnetic</span> field distribution, during a quasi-static evolution, can erupt to produce a CME. Methods: To model the full life span of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes we couple two models. The global non-linear force-free field (GNLFFF) evolution model is used to follow the quasi-static formation of a <span class="hlt">flux</span> rope. The MHD code ARMVAC is used to simulate the production of a CME through the loss of equilibrium and ejection of this <span class="hlt">flux</span> rope. Results: We show that the two distinct models may be successfully coupled and that the <span class="hlt">flux</span> rope is ejected out of our simulation box, where the outer boundary is placed at 2.5 R⊙. The plasma expelled during the <span class="hlt">flux</span> rope ejection travels outward at a speed of 100 km s-1, which is consistent with the observed speed of CMEs in the low corona. Conclusions: Our work shows that <span class="hlt">flux</span> ropes formed in the GNLFFF can lead to the ejection of a mass loaded <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope in full MHD simulations. Coupling the two distinct models opens up a new avenue of research to investigate phenomena where different phases of their evolution occur on drastically different time scales. Movies are available in electronic form at http://www.aanda.org</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22370419','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22370419"><span>Evolution of the <span class="hlt">magnetic</span> helicity <span class="hlt">flux</span> during the formation and eruption of <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Romano, P.; Zuccarello, F. P.; Guglielmino, S. L.; Zuccarello, F.</p> <p>2014-10-20</p> <p>We describe the evolution and the <span class="hlt">magnetic</span> helicity <span class="hlt">flux</span> for two active regions (ARs) since their appearance on the solar disk: NOAA 11318 and NOAA 11675. Both ARs hosted the formation and destabilization of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. In the former AR, the formation of the <span class="hlt">flux</span> rope culminated in a flare of C2.3 GOES class and a coronal mass ejection (CME) observed by Large Angle and Spectrometric Coronagraph Experiment. In the latter AR, the region hosting the <span class="hlt">flux</span> rope was involved in several flares, but only a partial eruption with signatures of a minor plasma outflow was observed. We found a different behavior in the accumulation of the <span class="hlt">magnetic</span> helicity <span class="hlt">flux</span> in the corona, depending on the <span class="hlt">magnetic</span> configuration and on the location of the <span class="hlt">flux</span> ropes in the ARs. Our results suggest that the complexity and strength of the photospheric <span class="hlt">magnetic</span> field is only a partial indicator of the real likelihood of an AR producing the eruption of a <span class="hlt">flux</span> rope and a subsequent CME.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ApJ...626.1096Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ApJ...626.1096Z"><span>Double Catastrophe of Coronal <span class="hlt">Flux</span> Rope in Quadrupolar <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y. Z.; Hu, Y. Q.; Wang, J. X.</p> <p>2005-06-01</p> <p>Using a relaxation method based on time-dependent ideal magnetohydrodynamic simulations, we find 2.5-dimensional force-free field solutions in spherical geometry, which are associated with an isolated <span class="hlt">flux</span> rope embedded in a quadrupolar background <span class="hlt">magnetic</span> field. The background field is of Antiochos type, consisting of a dipolar and an octopolar component with a neutral point somewhere in the equatorial plane. The <span class="hlt">flux</span> rope is characterized by its <span class="hlt">magnetic</span> <span class="hlt">fluxes</span>, including the annular <span class="hlt">flux</span> Φp and the axial <span class="hlt">magnetic</span> <span class="hlt">flux</span> Φϕ, and its geometric features described by the height of the rope axis and the length of the vertical current sheet below the rope. It is found that for a given Φp, the force-free field exhibits a complex catastrophic behavior with respect to increasing Φϕ. There exist two catastrophic points, and the catastrophic amplitude, measured by the jump in the height of the rope axis, is finite for both catastrophes. As a result, the <span class="hlt">flux</span> rope may levitate stably in the corona after catastrophe, with a transverse current sheet above and a vertical current sheet below. The <span class="hlt">magnetic</span> energy threshold for the two successive catastrophes are found to be larger than the corresponding partly open field energy. We argue that it is the transverse current sheet formed above the <span class="hlt">flux</span> rope that provides a downward Lorentz force on the <span class="hlt">flux</span> rope and thus keeps the rope levitating stably in the corona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004A%26A...426.1047A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004A%26A...426.1047A"><span>Emergence of <span class="hlt">magnetic</span> <span class="hlt">flux</span> from the convection zone into the corona</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Archontis, V.; Moreno-Insertis, F.; Galsgaard, K.; Hood, A.; O'Shea, E.</p> <p>2004-11-01</p> <p> the direction of the <span class="hlt">tube</span> axis and thus, given the twist of the <span class="hlt">magnetic</span> <span class="hlt">tube</span>, almost anti-parallel to the field lines at the upper boundary of the rising plasma ball. A thin, dome-shaped current layer is formed at the interface between the two <span class="hlt">flux</span> systems, in which ohmic dissipation and heating are taking place. The reconnection proceeds by merging successive layers on both sides of the reconnection site; however, this occurs not only at the cusp of the interface, but, also, gradually along its sides in the direction transverse to the ambient <span class="hlt">magnetic</span> field. The topology of the <span class="hlt">magnetic</span> field in the atmosphere is thereby modified: the reconnected field lines typically are part of the flanks of the <span class="hlt">tube</span> below the photosphere but then join the ambient field system in the corona and reach the boundaries of the domain as horizontal field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008P%26SS...56.1542S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008P%26SS...56.1542S"><span>Numerical simulation of small-scale low- β <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in the upper ionospheres of Venus and Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimazu, Hironori; Tanaka, Motohiko</p> <p>2008-10-01</p> <p>We use a three-dimensional macro-particle code (implicit-particle simulation) to examine the evolution of a small <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope, where "small" means that its radius is close to the kinetic length scale of protons or electrons. Small <span class="hlt">flux</span> ropes have been observed in the dayside ionospheres of Venus and Mars. In our simulations, we assume that the initial low- β force-free <span class="hlt">flux</span> rope is maintained by the electron current: an electron beam flows in the <span class="hlt">flux</span> rope along the <span class="hlt">magnetic</span> field lines. The simulation results show that electrostatic two-stream (Buneman) instability is generated around the <span class="hlt">flux</span> rope axis where the velocity of the electron beam is higher than the electron thermal velocity or the acoustic velocity. Electrons there are heated considerably in the direction parallel to the <span class="hlt">magnetic</span> field by the instability, and an electron hot <span class="hlt">tube</span> is formed. The <span class="hlt">magnetic</span> field deviates from the initial force-free field although the helical structure of the <span class="hlt">magnetic</span> field is maintained. These results indicate that the electron hot <span class="hlt">tubes</span> will be evidence of <span class="hlt">flux</span> rope formation in the low- β region, i.e., in the interaction region between the solar wind and the ionosphere, if they are found by high-resolution observations in the upper ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JaJAP..54h6601Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JaJAP..54h6601Y"><span><span class="hlt">Magnetic</span> hysteresis and <span class="hlt">magnetic</span> <span class="hlt">flux</span> patterns measured by acoustically stimulated electromagnetic response in a steel plate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamada, Hisato; Watanabe, Kakeru; Ikushima, Kenji</p> <p>2015-08-01</p> <p><span class="hlt">Magnetic</span> hysteresis loops are measured by ultrasonic techniques and used in visualizing the <span class="hlt">magnetic-flux</span> distribution in a steel plate. The piezomagnetic coefficient determines the amplitude of acoustically stimulated electromagnetic (ASEM) fields, yielding the hysteresis behavior of the intensity of the ASEM response. By utilizing the high correspondence of the ASEM response to the <span class="hlt">magnetic-flux</span> density, we image the specific spatial patterns of the <span class="hlt">flux</span> density formed by an artificial defect in a steel plate specimen. <span class="hlt">Magnetic-flux</span> probing by ultrasonic waves is thus shown to be a viable method of nondestructive material inspection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhG...44g5102W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhG...44g5102W"><span>Event-by-event study of space-time dynamics in <span class="hlt">flux-tube</span> fragmentation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wong, Cheuk-Yin</p> <p>2017-07-01</p> <p>In the semi-classical description of the <span class="hlt">flux-tube</span> fragmentation process for hadron production and hadronization in high-energy {e}+{e}- annihilations and pp collisions, the rapidity-space-time ordering and the local conservation laws of charge, flavor, and momentum provide a set of powerful tools that may allow the reconstruction of the space-time dynamics of quarks and mesons in exclusive measurements of produced hadrons, on an event-by-event basis. We propose procedures to reconstruct the space-time dynamics from event-by-event exclusive hadron data to exhibit explicitly the ordered chain of hadrons produced in a <span class="hlt">flux</span> <span class="hlt">tube</span> fragmentation. As a supplementary tool, we infer the average space-time coordinates of the q-\\bar{q} pair production vertices from the {π }- rapidity distribution data obtained by the NA61/SHINE Collaboration in pp collisions at \\sqrt{s}=6.3 to 17.3 GeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JLTP..tmp...66H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JLTP..tmp...66H"><span>Correlations Between <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> and Levitation Force of HTS Bulk Above a Permanent <span class="hlt">Magnet</span> Guideway</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Huan; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Haitao; Li, Jipeng; Deng, Zigang</p> <p>2017-06-01</p> <p>In order to clarify the correlations between <span class="hlt">magnetic</span> <span class="hlt">flux</span> and levitation force of the high-temperature superconducting (HTS) bulk, we measured the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density on bottom and top surfaces of a bulk superconductor while vertically moving above a permanent <span class="hlt">magnet</span> guideway (PMG). The levitation force of the bulk superconductor was measured simultaneously. In this study, the HTS bulk was moved down and up for three times between field-cooling position and working position above the PMG, followed by a relaxation measurement of 300 s at the minimum height position. During the whole processes, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density and levitation force of the bulk superconductor were recorded and collected by a multipoint <span class="hlt">magnetic</span> field measurement platform and a self-developed maglev measurement system, respectively. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> density on the bottom surface reflected the induced field in the superconductor bulk, while on the top, it reveals the penetrated <span class="hlt">magnetic</span> <span class="hlt">flux</span>. The results show that the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density and levitation force of the bulk superconductor are in direct correlation from the viewpoint of inner supercurrent. In general, this work is instructive for understanding the connection of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density, the inner current density and the levitation behavior of HTS bulk employed in a maglev system. Meanwhile, this <span class="hlt">magnetic</span> <span class="hlt">flux</span> density measurement method has enriched present experimental evaluation methods of maglev system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JLTP..189...42H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JLTP..189...42H"><span>Correlations Between <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> and Levitation Force of HTS Bulk Above a Permanent <span class="hlt">Magnet</span> Guideway</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Huan; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Haitao; Li, Jipeng; Deng, Zigang</p> <p>2017-10-01</p> <p>In order to clarify the correlations between <span class="hlt">magnetic</span> <span class="hlt">flux</span> and levitation force of the high-temperature superconducting (HTS) bulk, we measured the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density on bottom and top surfaces of a bulk superconductor while vertically moving above a permanent <span class="hlt">magnet</span> guideway (PMG). The levitation force of the bulk superconductor was measured simultaneously. In this study, the HTS bulk was moved down and up for three times between field-cooling position and working position above the PMG, followed by a relaxation measurement of 300 s at the minimum height position. During the whole processes, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density and levitation force of the bulk superconductor were recorded and collected by a multipoint <span class="hlt">magnetic</span> field measurement platform and a self-developed maglev measurement system, respectively. The <span class="hlt">magnetic</span> <span class="hlt">flux</span> density on the bottom surface reflected the induced field in the superconductor bulk, while on the top, it reveals the penetrated <span class="hlt">magnetic</span> <span class="hlt">flux</span>. The results show that the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density and levitation force of the bulk superconductor are in direct correlation from the viewpoint of inner supercurrent. In general, this work is instructive for understanding the connection of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density, the inner current density and the levitation behavior of HTS bulk employed in a maglev system. Meanwhile, this <span class="hlt">magnetic</span> <span class="hlt">flux</span> density measurement method has enriched present experimental evaluation methods of maglev system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1341640','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1341640"><span>Quantized Chiral <span class="hlt">Magnetic</span> Current from Reconnections of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hirono, Yuji; Kharzeev, Dmitri E.; Yin, Yi</p> <p>2016-10-20</p> <p>We introduce a new mechanism for the chiral <span class="hlt">magnetic</span> e ect that does not require an initial chirality imbalance. The chiral <span class="hlt">magnetic</span> current is generated by reconnections of <span class="hlt">magnetic</span> ux that change the <span class="hlt">magnetic</span> helicity of the system. The resulting current is entirely determined by the change of <span class="hlt">magnetic</span> helicity, and it is quantized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1257119','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1257119"><span>SQUIDs De-<span class="hlt">fluxing</span> Using a Decaying AC <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Matlashov, Andrei Nikolaevich; Semenov, Vasili Kirilovich; Anderson, Bill</p> <p>2016-06-08</p> <p><span class="hlt">Flux</span> trapping is the Achilles’ heel of all superconductor electronics. The most direct way to avoid <span class="hlt">flux</span> trapping is a prevention of superconductor circuits from exposure to <span class="hlt">magnetic</span> fields. Unfortunately this is not feasible if the circuits must be exposed to a strong DC <span class="hlt">magnetic</span> field even for a short period of time. For example, such unavoidable exposures take place in superparamagnetic relaxation measurements (SPMR) and ultra-low field <span class="hlt">magnetic</span> resonance imaging (ULF MRI) using unshielded thin-film SQUID-based gradiometers. Unshielded SQUIDs stop working after being exposed to DC <span class="hlt">magnetic</span> fields of only a few Gauss in strength. In this paper we present experimental results with de-<span class="hlt">fluxing</span> of planar thin-film LTS SQUID-based gradiometers using a strong decaying AC <span class="hlt">magnetic</span> field. We used four commercial G136 gradiometers for SPMR measurements with up to a 10 mT <span class="hlt">magnetizing</span> field. Strong 12.9 kHz decaying <span class="hlt">magnetic</span> field pulses reliably return SQUIDs to normal operation 50 ms after zeroing the DC <span class="hlt">magnetizing</span> field. This new AC de-<span class="hlt">fluxing</span> method was also successfully tested with seven other different types of LTS SQUID sensors and has been shown to dissipate extremely low energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21460125','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21460125"><span>SIGNATURES OF <span class="hlt">MAGNETIC</span> RECONNECTION AT BOUNDARIES OF INTERPLANETARY SMALL-SCALE <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> ROPES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tian Hui; Yao Shuo; Zong Qiugang; Qi Yu; He Jiansen</p> <p>2010-09-01</p> <p>The interaction between interplanetary small-scale <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes and the <span class="hlt">magnetic</span> field in the ambient solar wind is an important topic in the understanding of the evolution of <span class="hlt">magnetic</span> structures in the heliosphere. Through a survey of 125 previously reported small <span class="hlt">flux</span> ropes from 1995 to 2005, we find that 44 of them reveal clear signatures of Alfvenic fluctuations and thus classify them as Alfven wave trains rather than <span class="hlt">flux</span> ropes. Signatures of <span class="hlt">magnetic</span> reconnection, generally including a plasma jet of {approx}30 km s{sup -1} within a <span class="hlt">magnetic</span> field rotational region, are clearly present at boundaries of about 42% of the <span class="hlt">flux</span> ropes and 14% of the wave trains. The reconnection exhausts are often observed to show a local increase in the proton temperature, density, and plasma beta. About 66% of the reconnection events at <span class="hlt">flux</span> rope boundaries are associated with a <span class="hlt">magnetic</span> field shear angle larger than 90{sup 0} and 73% of them reveal a decrease of 20% or more in the <span class="hlt">magnetic</span> field magnitude, suggesting a dominance of anti-parallel reconnection at <span class="hlt">flux</span> rope boundaries. The occurrence rate of <span class="hlt">magnetic</span> reconnection at <span class="hlt">flux</span> rope boundaries through the years 1995-2005 is also investigated and we find that it is relatively low around the solar maximum and much higher when approaching solar minima. The average <span class="hlt">magnetic</span> field depression and shear angle for reconnection events at <span class="hlt">flux</span> rope boundaries also reveal a similar trend from 1995 to 2005. Our results demonstrate for the first time that boundaries of a substantial fraction of small-scale <span class="hlt">flux</span> ropes have properties similar to those of <span class="hlt">magnetic</span> clouds, in the sense that both of them exhibit signatures of <span class="hlt">magnetic</span> reconnection. The observed reconnection signatures could be related either to the formation of small <span class="hlt">flux</span> ropes or to the interaction between <span class="hlt">flux</span> ropes and the interplanetary <span class="hlt">magnetic</span> fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22118800','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22118800"><span>ORIGIN OF MACROSPICULE AND JET IN POLAR CORONA BY A SMALL-SCALE KINKED <span class="hlt">FLUX</span> <span class="hlt">TUBE</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kayshap, P.; Srivastava, Abhishek K.; Murawski, K.; Tripathi, Durgesh E-mail: aks@aries.res.in E-mail: durgesh@iucaa.ernet.in</p> <p>2013-06-10</p> <p>We report an observation of a small-scale <span class="hlt">flux</span> <span class="hlt">tube</span> that undergoes kinking and triggers the macrospicule and a jet on 2010 November 11 in the north polar corona. The small-scale <span class="hlt">flux</span> <span class="hlt">tube</span> emerged well before the triggering of the macrospicule and as time progresses the two opposite halves of this omega-shaped <span class="hlt">flux</span> <span class="hlt">tube</span> bent transversely and approach each other. After {approx}2 minutes, the two approaching halves of the kinked <span class="hlt">flux</span> <span class="hlt">tube</span> touch each other and an internal reconnection as well as an energy release takes place at the adjoining location and a macrospicule was launched which goes up to a height of 12 Mm. Plasma begins to move horizontally as well as vertically upward along with the onset of the macrospicule and thereafter converts into a large-scale jet in which the core denser plasma reaches up to {approx}40 Mm in the solar atmosphere with a projected speed of {approx}95 km s{sup -1}. The fainter and decelerating plasma chunks of this jet were also seen up to {approx}60 Mm. We perform a two-dimensional numerical simulation by considering the VAL-C initial atmospheric conditions to understand the physical scenario of the observed macrospicule and associated jet. The simulation results show that reconnection-generated velocity pulse in the lower solar atmosphere steepens into slow shock and the cool plasma is driven behind it in the form of macrospicule. The horizontal surface waves also appeared with shock fronts at different heights, which most likely drove and spread the large-scale jet associated with the macrospicule.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSH43A..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSH43A..06M"><span>Sigmoidal equilibria and eruptive instabilities in laboratory <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Myers, C. E.; Yamada, M.; Belova, E.; Ji, H.; Yoo, J.</p> <p>2013-12-01</p> <p>The <span class="hlt">Magnetic</span> Reconnection Experiment (MRX) has recently been modified to study quasi-statically driven line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in the context of storage-and-release eruptions in the corona. Detailed in situ <span class="hlt">magnetic</span> measurements and supporting MHD simulations permit quantitative analysis of the plasma behavior. We find that the behavior of these <span class="hlt">flux</span> ropes depends strongly on the properties of the applied potential <span class="hlt">magnetic</span> field arcade. For example, when the arcade is aligned parallel to the <span class="hlt">flux</span> rope footpoints, force free currents induced in the expanding rope modify the pressure and tension in the arcade, resulting in a confined, quiescent discharge with a saturated kink instability. When the arcade is obliquely aligned to the footpoints, on the other hand, a highly sigmoidal equilibrium forms that can dynamically erupt (see Fig. 1 and Fig. 2). To our knowledge, these storage-and-release eruptions are the first of their kind to be produced in the laboratory. A new 2D <span class="hlt">magnetic</span> probe array is used to map out the internal structure of the <span class="hlt">flux</span> ropes during both the storage and the release phases of the discharge. The kink instability and the torus instability are studied as candidate eruptive mechanisms--the latter by varying the vertical gradient of the potential field arcade. We also investigate <span class="hlt">magnetic</span> reconnection events that accompany the eruptions. The long-term objective of this work is to use internal <span class="hlt">magnetic</span> measurements of the <span class="hlt">flux</span> rope structure to better understand the evolution and eruption of comparable structures in the corona. This research is supported by DoE Contract Number DE-AC02-09CH11466 and by the Center for <span class="hlt">Magnetic</span> Self-Organization (CMSO). Qualitative sketches of <span class="hlt">flux</span> ropes formed in (1) a parallel potential field arcade; and (2) an oblique potential field arcade. One-dimensional <span class="hlt">magnetic</span> measurements from (1) a parallel arcade discharge that is confined; and (2) an oblique arcade discharge that erupts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/111419','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/111419"><span>A comparison of critical heat <span class="hlt">flux</span> in <span class="hlt">tubes</span> and bilaterally heated annuli</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Doerffer, S.; Groeneveld, D.C.; Cheng, S.C.</p> <p>1995-09-01</p> <p>This paper examines the critical heat <span class="hlt">flux</span> (CHF) behaviour for annular flow in bilaterally heated annuli and compares it to that in <span class="hlt">tubes</span> and unilaterally heated annuli. It was found that the differences in CHF between bilaterally and unilaterally heated annuli or <span class="hlt">tubes</span> strongly depend on pressure and quality. the CHF in bilaterally heated annuli can be predicted by <span class="hlt">tube</span> CHF prediction methods for the simultaneous CHF occurrence at both surfaces, and the following flow conditions: pressure 7-10 MPa, mass <span class="hlt">flux</span> 0.5-4.0 Mg/m{sup 2}s and critical quality 0.23-0.9. The effect on CHF of the outer-to-inner surface heat <span class="hlt">flux</span> ratio, was also examined. The prediction of CHF for bilaterally heated annuli was based on the droplet-diffusion model proposed by Kirillov and Smogalev. While their model refers only to CHF occurrence at the inner surface, we extended it to cases where CHF occurs at the outer surface, and simultaneously at both surfaces, thus covering all cases of CHF occurrence in bilaterally heated annuli. From the annuli CHF data of Becker and Letzter, we derived empirical functions required by the model. the proposed equations provide good accuracy for the CHF data used in this study. Moreover, the equations can predict conditions at which CHF occurs simultaneously at both surfaces. Also, this method can be used for cases with only one heated surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003SPD....34.1010M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003SPD....34.1010M"><span>Coronal Heating and the <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Content of the Network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moore, R. L.; Falconer, D. A.; Porter, J. G.; Hathaway, D. H.</p> <p>2003-05-01</p> <p>We investigate the heating of the quiet corona by measuring the increase of coronal luminosity with the amount of <span class="hlt">magnetic</span> <span class="hlt">flux</span> in the underlying network at solar minimum when there were no active regions on the face of the Sun. The coronal luminosity is measured from Fe IX/X-Fe XII pairs of coronal images from SOHO/EIT. The network <span class="hlt">magnetic</span> <span class="hlt">flux</span> content is measured from SOHO/MDI magnetograms. We find that the luminosity of the corona in our quiet regions increases roughly in proportion to the square root of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> content of the network and roughly in proportion to the length of the perimeter of the network <span class="hlt">magnetic</span> <span class="hlt">flux</span> clumps. From (1) this result, (2) other observations of many fine-scale explosive events at the edges of network <span class="hlt">flux</span> clumps, and (3) a demonstration that it is energetically feasible for the heating of the corona in quiet regions to be driven by explosions of granule-sized sheared-core <span class="hlt">magnetic</span> bipoles embedded in the edges of network <span class="hlt">flux</span> clumps, we infer that in quiet regions that are not influenced by active regions the corona is mainly heated by such <span class="hlt">magnetic</span> activity in the edges of the network <span class="hlt">flux</span> clumps. Our observational results together with our feasibility analysis allow us to predict that (1) at the edges of the network <span class="hlt">flux</span> clumps there are many transient sheared-core bipoles of the size and lifetime of granules and having transverse field strengths > 100 G, (2) 30 of these bipoles are present per supergranule, and (3) most spicules are produced by explosions of these bipoles. This work was supported by NASA's Office of Space Science through its Solar and Heliospheric Physics Supporting Research and Technology Program and its Sun-Earth Connection Guest Investigator Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMMM..410..226T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMMM..410..226T"><span>Re-direction of dc <span class="hlt">magnetic</span> <span class="hlt">flux</span> in <span class="hlt">magnetically</span> isotropic multilayered structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tarkhanyan, Roland H.; Niarchos, Dimitris G.</p> <p>2016-07-01</p> <p>Analytical design of a periodic composite structure allowing re-direction (bending) of dc <span class="hlt">magnetic</span> <span class="hlt">flux</span> with respect to applied external field is presented using methods of transformation optics. The composite structure is made of micrometer scale alternating layers of two different homogeneous and <span class="hlt">magnetically</span> isotropic materials. Dependence of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> bending angle on geometrical orientation of the layers as well as on the <span class="hlt">magnetic</span> permeability ratio is examined. Such structures can find use in various devices based on the control and manipulations of the <span class="hlt">magnetic</span> <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5223299','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5223299"><span>Vacuum <span class="hlt">magnetic</span> fields with dense <span class="hlt">flux</span> surfaces</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cary, J R</p> <p>1982-05-01</p> <p>A procedure is given for eliminating resonances and stochasticity in nonaxisymmetric vacuum toroidal <span class="hlt">magnetic</span> field. The results of this procedure are tested by the surface of section method. It is found that one can obtain <span class="hlt">magnetic</span> fields with increased rotational transform and decreased island structure while retaining basically the same winding law.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...797...49G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...797...49G"><span>The Solar Internetwork. I. Contribution to the Network <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gošić, M.; Bellot Rubio, L. R.; Orozco Suárez, D.; Katsukawa, Y.; del Toro Iniesta, J. C.</p> <p>2014-12-01</p> <p>The <span class="hlt">magnetic</span> network (NE) observed on the solar surface harbors a sizable fraction of the total quiet Sun <span class="hlt">flux</span>. However, its origin and maintenance are not well known. Here we investigate the contribution of internetwork (IN) <span class="hlt">magnetic</span> fields to the NE <span class="hlt">flux</span>. IN fields permeate the interior of supergranular cells and show large emergence rates. We use long-duration sequences of magnetograms acquired by Hinode and an automatic feature tracking algorithm to follow the evolution of NE and IN <span class="hlt">flux</span> elements. We find that 14% of the quiet Sun (QS) <span class="hlt">flux</span> is in the form of IN fields with little temporal variations. IN elements interact with NE patches and modify the <span class="hlt">flux</span> budget of the NE either by adding <span class="hlt">flux</span> (through merging processes) or by removing it (through cancellation events). Mergings appear to be dominant, so the net <span class="hlt">flux</span> contribution of the IN is positive. The observed rate of <span class="hlt">flux</span> transfer to the NE is 1.5 × 1024 Mx day-1 over the entire solar surface. Thus, the IN supplies as much <span class="hlt">flux</span> as is present in the NE in only 9-13 hr. Taking into account that not all the transferred <span class="hlt">flux</span> is incorporated into the NE, we find that the IN would be able to replace the entire NE <span class="hlt">flux</span> in approximately 18-24 hr. This renders the IN the most important contributor to the NE, challenging the view that ephemeral regions are the main source of <span class="hlt">flux</span> in the QS. About 40% of the total IN <span class="hlt">flux</span> eventually ends up in the NE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ApPhL..92s2508K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ApPhL..92s2508K"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise in MgB2 superconductor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khare, Neeraj; Singh, D. P.; Gupta, Ajai K.</p> <p>2008-05-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise in MgB2 polycrystalline sample is measured using a high-TC rf-superconducting quantum interference device in the temperature range of 6-40K. A small <span class="hlt">magnetic</span> field (˜200mG ) was applied while cooling the sample. The <span class="hlt">flux</span> noise exhibits 1/fα type of behavior with α ˜1.0-1.3 and shows enhanced noise around 24 and 37K. The <span class="hlt">flux</span> noise seems to originate from thermally activated vortex hopping. The large <span class="hlt">magnetic</span> noise at 24K indicates the presence of larger density of pinning sites with energies ˜0.061eV leading to enhanced <span class="hlt">magnetic</span> fluctuations at temperatures much below TC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22348151','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22348151"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> density in the heliosphere through several solar cycles</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Erdős, G.; Balogh, A.</p> <p>2014-01-20</p> <p>We studied the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density carried by solar wind to various locations in the heliosphere, covering a heliospheric distance range of 0.3-5.4 AU and a heliolatitudinal range from 80° south to 80° north. Distributions of the radial component of the <span class="hlt">magnetic</span> field, B{sub R} , were determined over long intervals from the Helios, ACE, STEREO, and Ulysses missions, as well as from using the 1 AU OMNI data set. We show that at larger distances from the Sun, the fluctuations of the <span class="hlt">magnetic</span> field around the average Parker field line distort the distribution of B{sub R} to such an extent that the determination of the unsigned, open solar <span class="hlt">magnetic</span> <span class="hlt">flux</span> density from the average (|B{sub R} |) is no longer justified. We analyze in detail two methods for reducing the effect of fluctuations. The two methods are tested using <span class="hlt">magnetic</span> field and plasma velocity measurements in the OMNI database and in the Ulysses observations, normalized to 1 AU. It is shown that without such corrections for the fluctuations, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density measured by Ulysses around the aphelion phase of the orbit is significantly overestimated. However, the matching between the in-ecliptic <span class="hlt">magnetic</span> <span class="hlt">flux</span> density at 1 AU (OMNI data) and the off-ecliptic, more distant, normalized <span class="hlt">flux</span> density by Ulysses is remarkably good if corrections are made for the fluctuations using either method. The main finding of the analysis is that the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density in the heliosphere is fairly uniform, with no significant variations having been observed either in heliocentric distance or heliographic latitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017HEAD...1610821S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017HEAD...1610821S"><span><span class="hlt">Magnetized</span> Black Hole Accretion Disks with Poloidal <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salvesen, Greg; Simon, Jacob B.; Armitage, Philip J.; Begelman, Mitchell C.</p> <p>2017-08-01</p> <p>Observations of blueshifted absorption lines associated with black hole X-ray binary accretion disk winds sometimes imply a <span class="hlt">magnetic</span> driving mechansim. To study the properties of <span class="hlt">magnetized</span> disks, we performed shearing box simulations (stratified, isothermal, ideal MHD) with different amounts of net vertical <span class="hlt">magnetic</span> <span class="hlt">flux</span>, spanning essentially the entire range over which the MRI is linearly unstable. This net vertical <span class="hlt">flux</span> sets the strength of the dominant toroidal field that is generated by the MRI-dynamo. Given sufficiently large net vertical <span class="hlt">flux</span>, <span class="hlt">magnetic</span> pressure support against gravity dominates throughout the vertical column of the disk. Without net poloidal <span class="hlt">flux</span>, a strongly <span class="hlt">magnetized</span> state cannot persist because the toroidal field buoyantly escapes faster than it can be replenished. With increasing disk <span class="hlt">magnetization</span>: (1) toroidal field reversals characteristic of the MRI-dynamo become less frequent and more sporadic and (2) gas density becomes more inhomogeneous, with field concentrating in low-density regions. We are currently investigating whether <span class="hlt">magnetic</span> pressure support in the disk atmosphere alters the disk continuum spectrum, which would bring the robustness of black hole spin measurements into question.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AAS...204.2004A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AAS...204.2004A"><span>Statistical Distribution of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Concentrations in an Active Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abramenko, V. I.</p> <p>2004-05-01</p> <p>Probability distribution functions (PDFs) of the unsigned <span class="hlt">magnetic</span> <span class="hlt">flux</span> content in <span class="hlt">flux</span> concentrations in a mature active region NOAA 9077 were calculated by using a set of 248 high resolution SOHO/MDI magnetograms. Two independent routines to outline <span class="hlt">magnetic</span> <span class="hlt">flux</span> concentrations were elaborated. The analysis was performed with 4 different values of the threshold, p, of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density (p=25, 50, 75, 100 G). We have found that: i) the best analytical approximation of the observed PDFs in the range of low <span class="hlt">flux</span> (1 x 1018 Mx < F < 150 x 1018 Mx ) is a lognormal distribution, LN(m ,s2), with the expected value m=(0.7-5) x 1018 Mx and the standard deviation s = (10-45) x 1018 Mx. The peak of the lognormal distribution tends to shift toward the lower <span class="hlt">flux</span> as the threshold p decreases. This tendency suggests that the real expected value may be even smaller than 0.7 x 1018 Mx; ii) for the <span class="hlt">flux</span> F > 150 x 1018 Mx the observed PDFs fall off slower than the lognormal approximation predicts. In this <span class="hlt">flux</span> range, the power law is found to be the best analytical approximation with the power law index approximately equal to 2. The transition region between the lognormality and the power law shifts toward the lower <span class="hlt">flux</span> as the threshold p is lowered. This implies that the functional form of the distribution changes continuously with the scale. The above findings are consistent with the concept of highly intermittent (or multifractal) nature of photospheric <span class="hlt">magnetic</span> fields and offer a new tool to study their multifractality. SOHO is a project of international cooperation between ESA and NASA. This work was supported by NSF-ATM 0076602, 9903515 and NASA NAG5-12782 grants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPD....4730306C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPD....4730306C"><span>Formation of sunspots and active regions through the emergence of <span class="hlt">magnetic</span> <span class="hlt">flux</span> generated in a solar convective dynamo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Feng; Rempel, Matthias D.; Fan, Yuhong</p> <p>2016-05-01</p> <p>We present a realistic numerical model of sunspot and active region formation through the emergence of <span class="hlt">flux</span> <span class="hlt">tubes</span> generated in a solar convective dynamo. The <span class="hlt">magnetic</span> and velocity fields in a horizontal layer near the top boundary of the solar convective dynamo simulation are used as a time-dependent bottom boundary to drive the near surface layer radiation MHD simulations of magneto-convection and <span class="hlt">flux</span> emergence with the MURaM code. The latter code simulates the emergence of the <span class="hlt">flux</span> <span class="hlt">tubes</span> through the upper most layer of the convection zone to the photosphere.The emerging <span class="hlt">flux</span> <span class="hlt">tubes</span> interact with the convection and break into small scale <span class="hlt">magnetic</span> elements that further rise to the photosphere. At the photosphere, several bipolar pairs of sunspots are formed through the coalescence of the small scale <span class="hlt">magnetic</span> elements. The sunspot pairs in the simulation successfully reproduce the fundamental observed properties of solar active regions, including the more coherent leading spots with a stronger field strength, and the correct tilts of the bipolar pairs. These asymmetries come most probably from the intrinsic asymmetries in the emerging fields imposed at the bottom boundary, where the horizontal fields are already tilted and the leading sides of the emerging <span class="hlt">flux</span> <span class="hlt">tubes</span> are usually up against the downdraft lanes of the giant cells. It is also found that penumbrae with numerous filamentary structures form in regions of strong horizontal <span class="hlt">magnetic</span> fields that naturally comes from the ongoing <span class="hlt">flux</span> emergence. In contrast to previous models, the penumbrae and umbrae are divided by very sharp boarders, which is highly consistent with observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980017166','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980017166"><span>Forced Convection Boiling and Critical Heat <span class="hlt">Flux</span> of Ethanol in Electrically Heated <span class="hlt">Tube</span> Tests</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meyer, Michael L.; Linne, Diane L.; Rousar, Donald C.</p> <p>1998-01-01</p> <p>Electrically heated <span class="hlt">tube</span> tests were conducted to characterize the critical heat <span class="hlt">flux</span> (transition from nucleate to film boiling) of subcritical ethanol flowing at conditions relevant to the design of a regeneratively cooled rocket engine thrust chamber. The coolant was SDA-3C alcohol (95% ethyl alcohol, 5% isopropyl alcohol by weight), and tests were conducted over the following ranges of conditions: pressure from 144 to 703 psia, flow velocities from 9.7 to 77 ft/s, coolant subcooling from 33 to 362 F, and critical heat <span class="hlt">fluxes</span> up to 8.7 BTU/in(exp 2)/sec. For the data taken near 200 psia, critical heat <span class="hlt">flux</span> was correlated as a function of the product of velocity and fluid subcooling to within +/- 20%. For data taken at higher pressures, an additional pressure term is needed to correlate the critical heat <span class="hlt">flux</span>. It was also shown that at the higher test pressures and/or flow rates, exceeding the critical heat <span class="hlt">flux</span> did not result in wall burnout. This result may significantly increase the engine heat <span class="hlt">flux</span> design envelope for higher pressure conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812800I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812800I"><span>Surprisingly low frequency attenuation effects in long <span class="hlt">tubes</span> when measuring turbulent <span class="hlt">fluxes</span> at tall towers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ibrom, Andreas; Brændholt, Andreas; Pilegaard, Kim</p> <p>2016-04-01</p> <p>The eddy covariance technique relies on the fast and accurate measurement of gas concentration fluctuations. While for some gasses robust and compact sensors are available, measurement of, e.g., non CO2 greenhouse gas <span class="hlt">fluxes</span> is often performed with sensitive equipment that cannot be run on a tower without massively disturbing the wind field. To measure CO and N2O <span class="hlt">fluxes</span>, we installed an eddy covariance system at a 125 m mast, where the gas analyser was kept in a laboratory close to the tower and the sampling was performed using a 150 m long <span class="hlt">tube</span> with a gas intake at 96 m height. We investigated the frequency attenuation and the time lag of the N2O and CO concentration measurements with a concentration step experiment. The results showed surprisingly high cut-off frequencies (close to 2 Hz) and small low-pass filter induced time lags (< 0.3 s), which were similar for CO and N2O. The results indicate that the concentration signal was hardly biased during the ca 10 s travel through the <span class="hlt">tube</span>. Due to the larger turbulence time scales at large measurement heights the low-pass correction was for the majority of the measurements < 5%. For water vapour the <span class="hlt">tube</span> attenuation was massive, which had, however, a positive effect by reducing both the water vapour dilution correction and the cross sensitivity effects on the N2O and CO <span class="hlt">flux</span> measurements. Here we present the set-up of the concentration step change experiment and its results and compare them with recently developed theories for the behaviour of gases in turbulent <span class="hlt">tube</span> flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016STP.....2a..19P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016STP.....2a..19P"><span>On the possibility for laboratory simulation of generation of Alfven disturbances in <span class="hlt">magnetic</span> <span class="hlt">tubes</span> in the solar atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prokopov, Pavel; Zaharov, Yuriy; Tishchenko, Vladimir; Boyarintsev, Eduard; Melehov, Aleksandr; Ponomarenko, Arnold; Posuh, Vitaliy; Shayhislamov, Ildar</p> <p>2016-03-01</p> <p>The paper deals with generation of Alfven plasma disturbances in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> through exploding laser plasma in <span class="hlt">magnetized</span> background plasma. Processes with similar effect of excitation of torsion-type waves seem to provide energy transfer from the solar photosphere to corona. The studies were carried out at experimental stand KI-1 represented a high-vacuum chamber of 1.2 m diameter, 5 m long, external <span class="hlt">magnetic</span> field up to 500 Gs along the chamber axis, and up to 2×10^-6 Torr pressure in operating mode. Laser plasma was produced when focusing the CO2 laser pulse on a flat polyethylene target, and then the laser plasma propagated in θ-pinch background hydrogen (or helium) plasma. As a result, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> of 15-20 cm radius was experimentally simulated along the chamber axis and the external <span class="hlt">magnetic</span> field direction. Also, the plasma density distribution in the <span class="hlt">tube</span> was measured. Alfven wave propagation along the <span class="hlt">magnetic</span> field was registered from disturbance of the <span class="hlt">magnetic</span> field transverse component B_ψ and field-aligned current J_z. The disturbances propagate at near-Alfven velocity of 70-90 km/s and they are of left-hand circular polarization of the transverse component of <span class="hlt">magnetic</span> field. Presumably, Alfven wave is generated by the <span class="hlt">magnetic</span> laminar mechanism of collisionless interaction between laser plasma cloud and background. The right-hand polarized high-frequency whistler predictor was registered which have been propagating before Alfven wave at 300 km/s velocity. The polarization direction changed with Alfven wave coming. Features of a slow magnetosonic wave as a sudden change in background plasma concentration along with simultaneous displacement of the external <span class="hlt">magnetic</span> field were found. The disturbance propagates at ~20-30 km/s velocity, which is close to that of ion sound at low plasma beta value. From preliminary estimates, the disturbance transfers about 10 % of the original energy of laser plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016STP.....2a..14P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016STP.....2a..14P"><span>On the possibility for laboratory simulation of generation of Alfven disturbances in <span class="hlt">magnetic</span> <span class="hlt">tubes</span> in the solar atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prokopov, Pavel; Zaharov, Yuriy; Tishchenko, Vladimir; Boyarintsev, Eduard; Melehov, Aleksandr; Ponomarenko, Arnold; Posuh, Vitaliy; Shayhislamov, Ildar</p> <p>2016-03-01</p> <p>The paper deals with generation of Alfven plasma disturbances in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> through exploding laser plasma in <span class="hlt">magnetized</span> background plasma. Processes with similar effect of excitation of torsion-type waves seem to provide energy transfer from the solar photosphere to corona. The studies were carried out at experimental stand KI-1 represented a high-vacuum chamber of 1.2 m diameter, 5 m long, external <span class="hlt">magnetic</span> field up to 500 Gs along the chamber axis, and up to 2×10^-6 Torr pressure in operating mode. Laser plasma was produced when focusing the CO2 laser pulse on a flat polyethylene target, and then the laser plasma propagated in θ-pinch background hydrogen (or helium) plasma. As a result, the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> of 15-20 cm radius was experimentally simulated along the chamber axis and the external <span class="hlt">magnetic</span> field direction. Also, the plasma density distribution in the <span class="hlt">tube</span> was measured. Alfven wave propagation along the <span class="hlt">magnetic</span> field was registered from disturbance of the <span class="hlt">magnetic</span> field transverse component B_ψ and field-aligned current J_z. The disturbances propagate at near-Alfven velocity of 70-90 km/s and they are of left-hand circular polarization of the transverse component of <span class="hlt">magnetic</span> field. Presumably, Alfven wave is generated by the <span class="hlt">magnetic</span> laminar mechanism of collisionless interaction between laser plasma cloud and background. The right-hand polarized high-frequency whistler predictor was registered which have been propagating before Alfven wave at 300 km/s velocity. The polarization direction changed with Alfven wave coming. Features of a slow magnetosonic wave as a sudden change in background plasma concentration along with simultaneous displacement of the external <span class="hlt">magnetic</span> field were found. The disturbance propagates at ~20-30 km/s velocity, which is close to that of ion sound at low plasma beta value. From preliminary estimates, the disturbance transfers about 10 % of the original energy of laser plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960021314&hterms=rust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drust','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960021314&hterms=rust&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drust"><span><span class="hlt">Magnetic</span> clouds, helicity conservation, and intrinsic scale <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kumar, A.; Rust, D. M.</p> <p>1995-01-01</p> <p>An intrinsic-scale <span class="hlt">flux</span>-rope model for interplanetary <span class="hlt">magnetic</span> clouds, incorporating conservation of <span class="hlt">magnetic</span> helicity, <span class="hlt">flux</span> and mass is found to adequately explain clouds' average thermodynamic and <span class="hlt">magnetic</span> properties. In spite their continuous expansion as they balloon into interplanetary space, <span class="hlt">magnetic</span> clouds maintain high temperatures. This is shown to be due to <span class="hlt">magnetic</span> energy dissipation. The temperature of an expanding cloud is shown to pass through a maximum above its starting temperature if the initial plasma beta in the cloud is less than 2/3. Excess <span class="hlt">magnetic</span> pressure inside the cloud is not an important driver of the expansion as it is almost balanced by the tension in the helical field lines. It is conservation of <span class="hlt">magnetic</span> helicity and <span class="hlt">flux</span> that requires that clouds expand radially as they move away from the Sun. Comparison with published data shows good agreement between measured cloud properties and theory. Parameters determined from theoretical fits to the data, when extended back to the Sun, are consistent with the origin of interplanetary <span class="hlt">magnetic</span> clouds in solar filament eruptions. A possible extension of the heating mechanism discussed here to heating of the solar corona is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21574690','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21574690"><span>THE EVOLUTION OF OPEN <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> DRIVEN BY PHOTOSPHERIC DYNAMICS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav S.; Antiochos, Spiro K. E-mail: lionel@predsci.com E-mail: titovv@predsci.com</p> <p>2011-04-20</p> <p>The coronal <span class="hlt">magnetic</span> field is of paramount importance in solar and heliospheric physics. Two profoundly different views of the coronal <span class="hlt">magnetic</span> field have emerged. In quasi-steady models, the predominant source of open <span class="hlt">magnetic</span> field is in coronal holes. In contrast, in the interchange model, the open <span class="hlt">magnetic</span> <span class="hlt">flux</span> is conserved, and the coronal <span class="hlt">magnetic</span> field can only respond to the photospheric evolution via interchange reconnection. In this view, the open <span class="hlt">magnetic</span> <span class="hlt">flux</span> diffuses through the closed, streamer belt fields, and substantial open <span class="hlt">flux</span> is present in the streamer belt during solar minimum. However, Antiochos and coworkers, in the form of a conjecture, argued that truly isolated open <span class="hlt">flux</span> cannot exist in a configuration with one heliospheric current sheet-it will connect via narrow corridors to the polar coronal hole of the same polarity. This contradicts the requirements of the interchange model. We have performed an MHD simulation of the solar corona up to 20 R{sub sun} to test both the interchange model and the Antiochos conjecture. We use a synoptic map for Carrington rotation 1913 as the boundary condition for the model, with two small bipoles introduced into the region where a positive polarity extended coronal hole forms. We introduce flows at the photospheric boundary surface to see if open <span class="hlt">flux</span> associated with the bipoles can be moved into the closed-field region. Interchange reconnection does occur in response to these motions. However, we find that the open <span class="hlt">magnetic</span> <span class="hlt">flux</span> cannot be simply injected into closed-field regions-the <span class="hlt">flux</span> eventually closes down and disconnected <span class="hlt">flux</span> is created. <span class="hlt">Flux</span> either opens or closes, as required, to maintain topologically distinct open- and closed-field regions, with no indiscriminate mixing of the two. The early evolution conforms to the Antiochos conjecture in that a narrow corridor of open <span class="hlt">flux</span> connects the portion of the coronal hole that is nearly detached by one of the bipoles. In the later evolution, a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007769','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007769"><span>The Evolution of Open <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Driven by Photospheric Dynamics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Linker, Jon A.; Lionello, Roberto; Mikic, Zoran; Titov, Viacheslav S.; Antiochos, Spiro K.</p> <p>2010-01-01</p> <p>The coronal <span class="hlt">magnetic</span> field is of paramount importance in solar and heliospheric physics. Two profoundly different views of the coronal <span class="hlt">magnetic</span> field have emerged. In quasi-steady models, the predominant source of open <span class="hlt">magnetic</span> field is in coronal holes. In contrast, in the interchange model, the open <span class="hlt">magnetic</span> <span class="hlt">flux</span> is conserved, and the coronal <span class="hlt">magnetic</span> field can only respond to the photospheric evolution via interchange reconnection. In this view the open <span class="hlt">magnetic</span> <span class="hlt">flux</span> diffuses through the closed, streamer belt fields, and substantial open <span class="hlt">flux</span> is present in the streamer belt during solar minimum. However, Antiochos and co-workers, in the form of a conjecture, argued that truly isolated open <span class="hlt">flux</span> cannot exist in a configuration with one heliospheric current sheet (HCS) - it will connect via narrow corridors to the polar coronal hole of the same polarity. This contradicts the requirements of the interchange model. We have performed an MHD simulation of the solar corona up to 20R solar to test both the interchange model and the Antiochos conjecture. We use a synoptic map for Carrington Rotation 1913 as the boundary condition for the model, with two small bipoles introduced into the region where a positive polarity extended coronal hole forms. We introduce flows at the photospheric boundary surface to see if open <span class="hlt">flux</span> associated with the bipoles can be moved into the closed-field region. Interchange reconnection does occur in response to these motions. However, we find that the open <span class="hlt">magnetic</span> <span class="hlt">flux</span> cannot be simply injected into closed-field regions - the <span class="hlt">flux</span> eventually closes down and disconnected <span class="hlt">flux</span> is created. <span class="hlt">Flux</span> either opens or closes, as required, to maintain topologically distinct open and closed field regions, with no indiscriminate mixing of the two. The early evolution conforms to the Antiochos conjecture in that a narrow corridor of open <span class="hlt">flux</span> connects the portion of the coronal hole that is nearly detached by one of the bipoles. In the later evolution, a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1348218','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1348218"><span>Dual-stage trapped-<span class="hlt">flux</span> <span class="hlt">magnet</span> cryostat for measurements at high <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Islam, Zahirul; Das, Ritesh K.; Weinstein, Roy</p> <p>2015-04-14</p> <p>A method and a dual-stage trapped-<span class="hlt">flux</span> <span class="hlt">magnet</span> cryostat apparatus are provided for implementing enhanced measurements at high <span class="hlt">magnetic</span> fields. The dual-stage trapped-<span class="hlt">flux</span> <span class="hlt">magnet</span> cryostat system includes a trapped-<span class="hlt">flux</span> <span class="hlt">magnet</span> (TFM). A sample, for example, a single crystal, is adjustably positioned proximate to the surface of the TFM, using a translation stage such that the distance between the sample and the surface is selectively adjusted. A cryostat is provided with a first separate thermal stage provided for cooling the TFM and with a second separate thermal stage provided for cooling sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15169477','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15169477"><span>Controlling the motion of <span class="hlt">magnetic</span> <span class="hlt">flux</span> quanta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, B Y; Marchesoni, F; Nori, Franco</p> <p>2004-05-07</p> <p>We study the transport of vortices in superconductors with triangular arrays of boomerang- or V-shaped asymmetric pinning wells, when applying an alternating electrical current. The asymmetry of the pinning landscape induces a very efficient "diode" effect, that allows the sculpting at will of the <span class="hlt">magnetic</span> field profile inside the sample. We present the first quantitative study of <span class="hlt">magnetic</span> "lensing" of fluxons inside superconductors. Our proposed vortex lens provides a near threefold increase of the vortex density at its "focus" regions. The main numerical features have been derived analytically.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1342783','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1342783"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Expulsion Studies in Niobium SRF Cavities</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Posen, Sam; Checchin, Mattia; Crawford, Anthony; Grassellino, Anna; Martinello, Martina; Melnychuk, Oleksandr; Romanenko, Alexander; Sergatskov, Dmitri; Trenikhina, Yulia</p> <p>2016-06-01</p> <p>With the recent discovery of nitrogen doping treatment for SRF cavities, ultra-high quality factors at medium accelerating fields are regularly achieved in vertical RF tests. To preserve these quality factors into the cryomodule, it is important to consider background <span class="hlt">magnetic</span> fields, which can become trapped in the surface of the cavity during cooldown and cause Q₀ degradation. Building on the recent discovery that spatial thermal gradients during cooldown can significantly improve expulsion of <span class="hlt">magnetic</span> <span class="hlt">flux</span>, a detailed study was performed of <span class="hlt">flux</span> expulsion on two cavities with different furnace treatments that are cooled in <span class="hlt">magnetic</span> fields amplitudes representative of what is expected in a realistic cryomodule. In this contribution, we summarize these cavity results, in order to improve understanding of the impact of <span class="hlt">flux</span> expulsion on cavity performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JHEP...01..065A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JHEP...01..065A"><span>Z N twisted orbifold models with <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abe, Tomo-hiro; Fujimoto, Yukihiro; Kobayashi, Tatsuo; Miura, Takashi; Nishiwaki, Kenji; Sakamoto, Makoto</p> <p>2014-01-01</p> <p>We propose new backgrounds of extra dimensions to lead to four-dimensional chiral models with three generations of matter fermions, that is T 2 /Z N twisted orbifolds with <span class="hlt">magnetic</span> <span class="hlt">fluxes</span>. We consider gauge theory on six-dimensional space-time, which contains the T 2 /Z N orbifold with <span class="hlt">magnetic</span> <span class="hlt">flux</span>, Scherk-Schwarz phases and Wilson line phases. We classify all the possible Scherk-Schwarz and Wilson line phases on T 2 /Z N orbifolds with <span class="hlt">magnetic</span> <span class="hlt">fluxes</span>. The behavior of zero modes is studied. We derive the number of zero modes for each eigenvalue of the Z N twist, showing explicitly examples of wave functions. We also investigate Kaluza-Klein mode functions and mass spectra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999AAS...194.3105L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999AAS...194.3105L"><span>The Pressure Limitations on <span class="hlt">Flux</span> Pile-Up <span class="hlt">Magnetic</span> Reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Litvinenko, Y. E.</p> <p>1999-05-01</p> <p><span class="hlt">Flux</span> pile-up <span class="hlt">magnetic</span> reconnection was thought to be able to provide fast energy dissipation a strongly <span class="hlt">magnetized</span> plasma, for example, in solar flares. We examine the problem of the plasma pressure limitations on the rapidity of <span class="hlt">flux</span> pile-up reconnection. It is shown that for a two-dimensional stagnation point flow with nonzero vorticity the <span class="hlt">magnetic</span> merging rate cannot exceed the Sweet-Parker scaling in a low-beta plasma, which is too slow to explain flares. Moreover, the solution has some undesireable properties such as a diffusion layer at the external boundary and the massively increasing inflow speed. The pressure limitation appears to be somewhat less restrictive for three-dimensional <span class="hlt">flux</span> pile-up. This work was supported by NSF grant ATM-9813933.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22521503','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22521503"><span>DO THE LEGS OF <span class="hlt">MAGNETIC</span> CLOUDS CONTAIN TWISTED <span class="hlt">FLUX</span>-ROPE <span class="hlt">MAGNETIC</span> FIELDS?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Owens, M. J.</p> <p>2016-02-20</p> <p><span class="hlt">Magnetic</span> clouds (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized primarily by a smooth rotation in the <span class="hlt">magnetic</span> field direction indicative of the presence of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope. Energetic particle signatures suggest MC <span class="hlt">flux</span> ropes remain <span class="hlt">magnetically</span> connected to the Sun at both ends, leading to widely used model of global MC structure as an extended <span class="hlt">flux</span> rope, with a loop-like axis stretching out from the Sun into the heliosphere and back to the Sun. The time of flight of energetic particles, however, suggests shorter <span class="hlt">magnetic</span> field line lengths than such a continuous twisted <span class="hlt">flux</span> rope would produce. In this study, two simple models are compared with observed <span class="hlt">flux</span> rope axis orientations of 196 MCs to show that the <span class="hlt">flux</span> rope structure is confined to the MC leading edge. The MC “legs,” which <span class="hlt">magnetically</span> connect the <span class="hlt">flux</span> rope to the Sun, are not recognizable as MCs and thus are unlikely to contain twisted <span class="hlt">flux</span> rope fields. Spacecraft encounters with these non-<span class="hlt">flux</span> rope legs may provide an explanation for the frequent observation of non-MC ICMEs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...818..197O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...818..197O"><span>Do the Legs of <span class="hlt">Magnetic</span> Clouds Contain Twisted <span class="hlt">Flux</span>-rope <span class="hlt">Magnetic</span> Fields?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Owens, M. J.</p> <p>2016-02-01</p> <p><span class="hlt">Magnetic</span> clouds (MCs) are a subset of interplanetary coronal mass ejections (ICMEs) characterized primarily by a smooth rotation in the <span class="hlt">magnetic</span> field direction indicative of the presence of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope. Energetic particle signatures suggest MC <span class="hlt">flux</span> ropes remain <span class="hlt">magnetically</span> connected to the Sun at both ends, leading to widely used model of global MC structure as an extended <span class="hlt">flux</span> rope, with a loop-like axis stretching out from the Sun into the heliosphere and back to the Sun. The time of flight of energetic particles, however, suggests shorter <span class="hlt">magnetic</span> field line lengths than such a continuous twisted <span class="hlt">flux</span> rope would produce. In this study, two simple models are compared with observed <span class="hlt">flux</span> rope axis orientations of 196 MCs to show that the <span class="hlt">flux</span> rope structure is confined to the MC leading edge. The MC “legs,” which <span class="hlt">magnetically</span> connect the <span class="hlt">flux</span> rope to the Sun, are not recognizable as MCs and thus are unlikely to contain twisted <span class="hlt">flux</span> rope fields. Spacecraft encounters with these non-<span class="hlt">flux</span> rope legs may provide an explanation for the frequent observation of non-MC ICMEs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19044519','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19044519"><span>Measurement of <span class="hlt">magnetic</span> fluctuation-induced particle <span class="hlt">flux</span> (invited).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ding, W X; Brower, D L; Yates, T Y</p> <p>2008-10-01</p> <p><span class="hlt">Magnetic</span> field fluctuation-induced particle transport has been directly measured in the high-temperature core of the MST reversed field pinch plasma. Measurement of radial particle transport is achieved by combining various interferometry techniques, including Faraday rotation, conventional interferometry, and differential interferometry. It is observed that electron convective particle <span class="hlt">flux</span> and its divergence exhibit a significant increase during a sawtooth crash. In this paper, we describe the basic techniques employed to determine the particle <span class="hlt">flux</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26690435','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26690435"><span>Theory and Application of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Leakage Pipeline Detection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shi, Yan; Zhang, Chao; Li, Rui; Cai, Maolin; Jia, Guanwei</p> <p>2015-12-10</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> leakage (MFL) detection is one of the most popular methods of pipeline inspection. It is a nondestructive testing technique which uses <span class="hlt">magnetic</span> sensitive sensors to detect the <span class="hlt">magnetic</span> leakage field of defects on both the internal and external surfaces of pipelines. This paper introduces the main principles, measurement and processing of MFL data. As the key point of a quantitative analysis of MFL detection, the identification of the leakage <span class="hlt">magnetic</span> signal is also discussed. In addition, the advantages and disadvantages of different identification methods are analyzed. Then the paper briefly introduces the expert systems used. At the end of this paper, future developments in pipeline MFL detection are predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4721765','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4721765"><span>Theory and Application of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Leakage Pipeline Detection</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shi, Yan; Zhang, Chao; Li, Rui; Cai, Maolin; Jia, Guanwei</p> <p>2015-01-01</p> <p><span class="hlt">Magnetic</span> <span class="hlt">flux</span> leakage (MFL) detection is one of the most popular methods of pipeline inspection. It is a nondestructive testing technique which uses <span class="hlt">magnetic</span> sensitive sensors to detect the <span class="hlt">magnetic</span> leakage field of defects on both the internal and external surfaces of pipelines. This paper introduces the main principles, measurement and processing of MFL data. As the key point of a quantitative analysis of MFL detection, the identification of the leakage <span class="hlt">magnetic</span> signal is also discussed. In addition, the advantages and disadvantages of different identification methods are analyzed. Then the paper briefly introduces the expert systems used. At the end of this paper, future developments in pipeline MFL detection are predicted. PMID:26690435</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22348265','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22348265"><span>Three-dimensional prominence-hosting <span class="hlt">magnetic</span> configurations: Creating a helical <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Xia, C.; Keppens, R.; Guo, Y.</p> <p>2014-01-10</p> <p>The <span class="hlt">magnetic</span> configuration hosting prominences and their surrounding coronal structure is a key research topic in solar physics. Recent theoretical and observational studies strongly suggest that a helical <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope is an essential ingredient to fulfill most of the theoretical and observational requirements for hosting prominences. To understand <span class="hlt">flux</span> rope formation details and obtain <span class="hlt">magnetic</span> configurations suitable for future prominence formation studies, we here report on three-dimensional isothermal magnetohydrodynamic simulations including finite gas pressure and gravity. Starting from a magnetohydrostatic corona with a linear force-free bipolar <span class="hlt">magnetic</span> field, we follow its evolution when introducing vortex flows around the main polarities and converging flows toward the polarity inversion line near the bottom of the corona. The converging flows bring the feet of different loops together at the polarity inversion line, where <span class="hlt">magnetic</span> reconnection and <span class="hlt">flux</span> cancellation happen. Inflow and outflow signatures of the <span class="hlt">magnetic</span> reconnection process are identified, and thereby the newly formed helical loops wind around preexisting ones so that a complete <span class="hlt">flux</span> rope grows and ascends. When a macroscopic <span class="hlt">flux</span> rope is formed, we switch off the driving flows and find that the system relaxes to a stable state containing a helical <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope embedded in an overlying arcade structure. A major part of the formed <span class="hlt">flux</span> rope is threaded by dipped field lines that can stably support prominence matter, while the total mass of the <span class="hlt">flux</span> rope is in the order of 4-5× 10{sup 14} g.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24g2108D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24g2108D"><span>Helicity transformation under the collision and merging of two <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>DeHaas, Timothy; Gekelman, Walter</p> <p>2017-07-01</p> <p><span class="hlt">Magnetic</span> helicity has become a useful tool in the analysis of astrophysical plasmas. Its conservation in the magnetohydrodynamic limit (and other fluid approaches) constrains the global behavior of large plasma structures. One such astrophysical structure is a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope: a <span class="hlt">tube</span>-like, current-carrying plasma embedded in an external <span class="hlt">magnetic</span> field. Bundles of these ropes are commonly observed in the near-earth environment and solar atmosphere. In this well-diagnosed experiment (three-dimensional measurements of ne, Te, Vp, B, J, E, and uflow), two <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes are generated in the Large Plasma Device at UCLA. These ropes are driven kink-unstable to trigger complex motion. As they interact, helicity conservation is examined in regions of reconnection. We examine (1) the transport of helicity and (2) the dissipation of the helicity. As the ropes move and the topology of the field lines diverge, a quasi-separatrix layer (QSL) is formed. As the QSL forms, <span class="hlt">magnetic</span> helicity is dissipated within this region. At the same time, there is an influx of canonical helicity into the region such that the temporal derivative of <span class="hlt">magnetic</span> helicity is zero.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2523R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2523R"><span>Determining the axis orientation of cylindrical <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rong, Zhaojin; Wan, Weixing; Shen, Chao; Zhang, Tielong; Lui, Anthony; Wang, Yuming; Dunlop, malcolm; Zhang, Yongcun; Zong, Qiugang</p> <p>2013-04-01</p> <p>We develop a new simple method for inferring the orientation of a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope, which is assumed to be a time-independent cylindrically symmetric structure via the direct single-point analysis of <span class="hlt">magnetic</span> field structure. The model tests demonstrate that, for the cylindrical <span class="hlt">flux</span> rope regardless of whether it is force-free or not, the method can consistently yield the axis orientation of the <span class="hlt">flux</span> rope with higher accuracy and stability than the minimum variance analysis of the <span class="hlt">magnetic</span> field and the Grad-Shafranov reconstruction technique. Moreover, the radial distance to the axis center and the current density can also be estimated consistently. Application to two actual <span class="hlt">flux</span> transfer events observed by the four satellites of the Cluster mission demonstrates that the method is more appropriate to be used for the inner part of <span class="hlt">flux</span> rope, which might be closer to the cylindrical structure, showing good agreement with the results obtained from the optimal Grad-Shafranov reconstruction and the least squares technique of Faraday's law, but fails to produce such agreement for the outer satellite that grazes the <span class="hlt">flux</span> rope. Therefore, the method must be used with caution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPlPh..81e4901G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPlPh..81e4901G"><span>Hamiltonian <span class="hlt">magnetic</span> reconnection with parallel electron heat <span class="hlt">flux</span> dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grasso, D.; Tassi, E.</p> <p>2015-10-01</p> <p>> We analyse, both analytically and numerically, a two-dimensional six-field fluid model for collisionless <span class="hlt">magnetic</span> reconnection, accounting for temperature and heat <span class="hlt">flux</span> fluctuations along the direction of the <span class="hlt">magnetic</span> guide field. We show that the model possesses a Hamiltonian structure with a non-canonical Poisson bracket. This bracket is characterized by the presence of six infinite families of Casimirs, associated with Lagrangian invariants. This reveals that the model can be reformulated as a system of advection equations, thus generalizing previous results obtained for Hamiltonian isothermal fluid models for reconnection. Numerical simulations indicate that the presence of heat <span class="hlt">flux</span> and temperature fluctuations yields slightly larger growth rates and similar saturated island amplitudes, with respect to the isothermal models. For values of the sonic Larmor radius much smaller than the electron skin depth, heat <span class="hlt">flux</span> fluctuations tend to be suppressed and temperature fluctuations follow density fluctuations. Increasing the sonic Larmor radius results in an increasing fraction of <span class="hlt">magnetic</span> energy converted into heat <span class="hlt">flux</span>, at the expense of temperature fluctuations. In particular, heat <span class="hlt">flux</span> fluctuations tend to become relevant along the <span class="hlt">magnetic</span> island separatrices. The qualitative structures associated with the electron field variables are also reinterpreted in terms of the rotation of the Lagrangian invariants of the system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...842....3N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...842....3N"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Emergence and Decay Rates for Preceder and Follower Sunspots Observed with HMI</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norton, A. A.; Jones, E. H.; Linton, M. G.; Leake, J. E.</p> <p>2017-06-01</p> <p>We quantify the emergence and decay rates of preceder (p) and follower (f) sunspots within 10 active regions from 2010 to 2014 using Space-weather Helioseismic <span class="hlt">Magnetic</span> Imager Active Region Patch data. The sunspots are small to mid-sized regions and contain a signed <span class="hlt">flux</span> within a single polarity sunspot of (1.1{--}6.5)× {10}21 {Mx}. The net unsigned <span class="hlt">flux</span> within the regions, including plage, ranges from (5.1{--}20)× {10}21 {Mx}. Rates are calculated with and without intensity contours to differentiate between sunspot formation and <span class="hlt">flux</span> emergence. Signed <span class="hlt">flux</span> emergence rates, calculated with intensity contours, for the p (f) spots average 6.8(4.9)× {10}19 {Mx} hr-1, while decay rates are -1.9(-3.4)× {10}19 {Mx} hr-1. The mean, signed <span class="hlt">flux</span> emergence rate of the regions, including plage, is 7.1× {10}19 {Mx} hr-1, for a mean peak <span class="hlt">flux</span> of 5.9× {10}21 {Mx}. Using a synthesis of these results and others reported previously, there is a clear trend for larger <span class="hlt">flux</span> regions to emerge faster than smaller ones. Observed emergence rates (dφ /{dt}, Mx hr-1) scale with total signed peak <span class="hlt">flux</span>, {\\tilde{φ }}\\max , as a power law with an exponent of 0.36, i.e., dφ /{dt}=A{\\tilde{φ }}\\max 0.36. The observed rates may assist in constraining the boundary and initial conditions in simulations which already demonstrate increased rates for <span class="hlt">flux</span> <span class="hlt">tubes</span> with higher buoyancy and twist, or in the presence of a strong upflow. Overall, the observed emergence rates are smaller than those in simulations, which may indicate a slower rise of the <span class="hlt">flux</span> in the interior than what is captured in simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...840...20S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...840...20S"><span>Propagation of Torsional Alfvén Waves from the Photosphere to the Corona: Reflection, Transmission, and Heating in Expanding <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soler, Roberto; Terradas, Jaume; Oliver, Ramón; Ballester, José Luis</p> <p>2017-05-01</p> <p>It has been proposed that Alfvén waves play an important role in the energy propagation through the solar atmospheric plasma and its heating. Here we theoretically investigate the propagation of torsional Alfvén waves in <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tubes</span> expanding from the photosphere up to the low corona and explore the reflection, transmission, and dissipation of wave energy. We use a realistic variation of the plasma properties and the <span class="hlt">magnetic</span> field strength with height. Dissipation by ion-neutral collisions in the chromosphere is included using a multifluid partially ionized plasma model. Considering the stationary state, we assume that the waves are driven below the photosphere and propagate to the corona, while they are partially reflected and damped in the chromosphere and transition region. The results reveal the existence of three different propagation regimes depending on the wave frequency: low frequencies are reflected back to the photosphere, intermediate frequencies are transmitted to the corona, and high frequencies are completely damped in the chromosphere. The frequency of maximum transmissivity depends on the <span class="hlt">magnetic</span> field expansion rate and the atmospheric model, but is typically in the range of 0.04-0.3 Hz. <span class="hlt">Magnetic</span> field expansion favors the transmission of waves to the corona and lowers the reflectivity of the chromosphere and transition region compared to the case with a straight field. As a consequence, the chromospheric heating due to ion-neutral dissipation systematically decreases when the expansion rate of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> <span class="hlt">tube</span> increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010521','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010521"><span>Sabots, Obturator and Gas-In-Launch <span class="hlt">Tube</span> Techniques for Heat <span class="hlt">Flux</span> Models in Ballistic Ranges</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogdanoff, David W.; Wilder, Michael C.</p> <p>2013-01-01</p> <p>For thermal protection system (heat shield) design for space vehicle entry into earth and other planetary atmospheres, it is essential to know the augmentation of the heat <span class="hlt">flux</span> due to vehicle surface roughness. At the NASA Ames Hypervelocity Free Flight Aerodynamic Facility (HFFAF) ballistic range, a campaign of heat <span class="hlt">flux</span> studies on rough models, using infrared camera techniques, has been initiated. Several phenomena can interfere with obtaining good heat <span class="hlt">flux</span> data when using this measuring technique. These include leakage of the hot drive gas in the gun barrel through joints in the sabot (model carrier) to create spurious thermal imprints on the model forebody, deposition of sabot material on the model forebody, thereby changing the thermal properties of the model surface and unknown in-barrel heating of the model. This report presents developments in launch techniques to greatly reduce or eliminate these problems. The techniques include the use of obturator cups behind the launch package, enclosed versus open front sabot designs and the use of hydrogen gas in the launch <span class="hlt">tube</span>. Attention also had to be paid to the problem of the obturator drafting behind the model and impacting the model. Of the techniques presented, the obturator cups and hydrogen in the launch <span class="hlt">tube</span> were successful when properly implemented</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPDI2001D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPDI2001D"><span>Helicity Transformation under the Collision and Merging of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dehaas, Timothy</p> <p>2016-10-01</p> <p>A <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope is a <span class="hlt">tube</span>-like, current carrying plasma embedded in an external <span class="hlt">magnetic</span> field. The <span class="hlt">magnetic</span> field lines resemble threads in a rope, which vary in pitch according to radius. <span class="hlt">Flux</span> ropes are ubiquitous in astrophysical plasmas, and bundles of these structures play an important role in the dynamics of the space environment. They are observed in the solar atmosphere and near-earth environment where they are seen to twist, merge, tear, and writhe. In this MHD context, their global dynamics are bound by rules of <span class="hlt">magnetic</span> helicity conservation, unless, under a non-ideal process, helicity is transformed through <span class="hlt">magnetic</span> reconnection, turbulence, or localized instabilities. These processes are tested under experimental conditions in the Large Plasma Device (LAPD). The device is a twenty-meter long, one-meter diameter, cylindrical vacuum vessel designed to generate a highly reproducible, <span class="hlt">magnetized</span> plasma. Reliable shot-to-shot repetition of plasma parameters and over four hundred diagnostic ports enable the collection of volumetric datasets (measurements of ne, Te, Vp, B, J, E, uflow) as two kink-unstable <span class="hlt">flux</span> ropes form, move, collide, and merge. Similar experiments on the LAPD have utilized these volumetric datasets, visualizing <span class="hlt">magnetic</span> reconnection through a topological quasi-separatrix layer, or QSL. This QSL is shown to be spatially coincident with the reconnection rate, ∫ E . dl , and oscillates (although out of phase) with global helicity. <span class="hlt">Magnetic</span> helicity is observed to have a negative sign and its counterpart, cross helicity, a positive one. These quantities oscillate 8% peak-to-peak, and the changes in helicity are visualized as 1) the transport of helicity (ϕB + E × A) and 2) the dissipation of the helicity - 2 E . B . This work is supported by LANL-UC research Grant and done at the Basic Plasma Science Facility, which is funded by DOE and NSF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPTM9004I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPTM9004I"><span><span class="hlt">Magnetic</span> field generation from shear flow in <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Intrator, T. P.; Sears, J.; Gao, K.; Klarenbeek, J.; Yoo, C.</p> <p>2012-10-01</p> <p>In the Reconnection Scaling Experiment (RSX) we have measured out of plane quadrupole <span class="hlt">magnetic</span> field structure in situations where <span class="hlt">magnetic</span> reconnection was minimal. This quadrupole out of plane <span class="hlt">magnetic</span> signature has historically been presumed to be the smoking gun harbinger of reconnection. On the other hand, we showed that when <span class="hlt">flux</span> ropes bounced instead of merging and reconnecting, this signature could evolve. This can follow from sheared fluid flows in the context of a generalized Ohms Law. We reconstruct a shear flow model from experimental data for <span class="hlt">flux</span> ropes that have been experimentally well characterized in RSX as screw pinch equilibria, including plasma ion and electron flow, with self consistent profiles for <span class="hlt">magnetic</span> field, pressure, and current density. The data can account for the quadrupole field structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006ApJ...648L..71S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006ApJ...648L..71S"><span><span class="hlt">Magnetic</span> Helicity Density and Its <span class="hlt">Flux</span> in Weakly Inhomogeneous Turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Subramanian, Kandaswamy; Brandenburg, Axel</p> <p>2006-09-01</p> <p>A gauge-invariant and hence physically meaningful definition of <span class="hlt">magnetic</span> helicity density for random fields is proposed, using the Gauss linking formula, as the density of correlated field line linkages. This definition is applied to the random small-scale field in weakly inhomogeneous turbulence, whose correlation length is small compared with the scale on which the turbulence varies. For inhomogeneous systems, with or without boundaries, our technique then allows one to study the local <span class="hlt">magnetic</span> helicity density evolution in a gauge-independent fashion, which was not possible earlier. This evolution equation is governed by local sources (owing to the mean field) and by the divergence of a <span class="hlt">magnetic</span> helicity <span class="hlt">flux</span> density. The role of <span class="hlt">magnetic</span> helicity <span class="hlt">fluxes</span> in alleviating catastrophic quenching of mean field dynamos is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010MsT..........3M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010MsT..........3M"><span>A <span class="hlt">magnetic</span> <span class="hlt">flux</span> leakage NDE system for CANDU feeder pipes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mak, Thomas Don</p> <p></p> <p>This work examines the application of different <span class="hlt">magnetic</span> <span class="hlt">flux</span> leakage (MFL) inspection concepts to the non destructive evaluation (NDE) of residual (elastic) stresses in CANDURTM reactor feeder pipes. The stress sensitivity of three MFL inspection techniques was examined with flat plate samples, with stress-induced <span class="hlt">magnetic</span> anisotropy (SMA) demonstrating the greatest stress sensitivity. A prototype SMA testing system was developed to apply <span class="hlt">magnetic</span> NDE to feeders. The system consists of a <span class="hlt">flux</span> controller that incorporates feedback from a wire coil and a Hall sensor (FCV2), and a <span class="hlt">magnetic</span> anisotropy prototype (MAP) probe. The combination of FCV2 and the MAP probe was shown to provide SMA measurements on feeder pipe samples and predict stresses from SMA measurements with a mean accuracy of +/-38MPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992vswc.reptQ....C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992vswc.reptQ....C"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span>-load current interactions in ferrous conductors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cannell, Michael J.; McConnell, Richard A.</p> <p>1992-06-01</p> <p>A modeling technique has been developed to account for interactions between load current and <span class="hlt">magnetic</span> <span class="hlt">flux</span> in an iron conductor. Such a conductor would be used in the active region of a normally conducting homopolar machine. This approach has been experimentally verified and its application to a real machine demonstrated. Additionally, measurements of the resistivity of steel under the combined effects of <span class="hlt">magnetic</span> field and current have been conducted.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA181642','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA181642"><span>Experimental Results from Railgun Firings Involving <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Probes.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1986-12-01</p> <p>of railgun firings, the voltages induced in small solenoidal probes mounted in different positions and orientations along the barrel were measured to...different positions and orientations along the barrel were measured to gain a better understanding of the current density and <span class="hlt">magnetic</span> field in a...ACKNOWLEDGEMENTS 7. REFERENCES 10 I’. 4¢ EXPERIMENTAL RESULTS FROM RAILGUN FIRINGS INVOLVING <span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> PROBES 1. INTRODUCTION The Lorentz force acting on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT.......295C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT.......295C"><span>Manipulation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> landscapes in superconducting BSCCO crystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cole, David</p> <p></p> <p>We present data showing the exploration of the dynamic behaviour of vortices in the high critical temperature. Type II superconductor Bi2Sr2CaCu2O8+5. Under tilted <span class="hlt">magnetic</span> fields the <span class="hlt">flux</span> penetration in a layered superconductor is composed of a complex and rich series of ground states. The existence of interacting orthogonal crossing lattices has led to the proposal of two techniques for the manipulation of vortices and the control of micromagnetic profiles. We show that we can manipulate the local PV density via a variation in the in-plane field, H//. This technique involves moving Josephson vortices that drag pancake vortex stacks, and allows us to manipulate the <span class="hlt">magnetic</span> profile, Bz(x), across the entire sample. Depending on the <span class="hlt">magnetic</span> history and the temperature we can increase or decrease the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density at the center and near the edges of the crystal by as much as 40%, realising both "convex" and "concave" <span class="hlt">magnetic</span> <span class="hlt">flux</span> lenses. A requirement of many recently proposed nanodevices for the control of the motion of tiny particles is a nanoengineered, spatially-asymmetric substrate. However, using recent theoretical ideas, we demonstrate experimentally how to guide <span class="hlt">flux</span> quanta using a drive that is asymmetric in time instead of being asymmetric in space. By varying the time-asymmetry of the drive, we are able experimentally to increase or decrease the density of <span class="hlt">magnetic</span> <span class="hlt">flux</span> at the centre of superconducting samples that have no spatial ratchet substrate. This is the first ratchet that depends upon a temporal rather than a spatial ratchet potential. These two techniques involve no permanent nanofabrication of the sample and are non-invasive and flexible. The manipulation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> quanta could be used to reduce <span class="hlt">flux</span> noise in sensitive superconducting devices such as SQUIDs and high frequency filters and has possible future applications in the manipulation of <span class="hlt">flux</span> bits in superconducting quantum computers. The experimental results are well</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DNP.EA159W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DNP.EA159W"><span>Testing of Photomultiplier <span class="hlt">Tubes</span> in a <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Waldron, Zachary; A1 Collaboration</p> <p>2016-09-01</p> <p>The A1 collaboration at MAMI in Mainz, Germany has designed a neutron detector that can be used in experiments to measure the electric form factor of the neutron. They will measure elastic scattering from the neutron, using the polarized electron beam from MAMI at A1's experimental hall. The detector will be composed of two walls of staggered scintillator bars which will be read out by photomultiplier <span class="hlt">tubes</span> (PMT), connected to both ends of each scintillator via light guides. The experiment requires a <span class="hlt">magnetic</span> field with strength of 1 Tesla, 2m away from the first scintillator wall. The resulting fringe field is sufficient to disrupt the PMTs, despite the addition of Mu Metal shielding. The effects of the fringe field on these PMTs was tested to optimize the amplification of the PMTs. A Helmholtz Coil was designed to generate a controlled <span class="hlt">magnetic</span> field with equivalent strength to the field that the PMTs will encounter. The PMTs were read out using a multi-channel analyzer, were tested at various angles relative to the <span class="hlt">magnetic</span> field in order to determine the optimal orientation to minimize signal disruption. Tests were also performed to determine: the neutron detector response to cosmic radiation; and the best method for measuring a <span class="hlt">magnetic</span> field's strength in two dimensions. National Science Foundation Grant No. IIA-1358175.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...637937B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...637937B"><span>Radiation-induced <span class="hlt">magnetization</span> reversal causing a large <span class="hlt">flux</span> loss in undulator permanent <span class="hlt">magnets</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi</p> <p>2016-11-01</p> <p>We report an unexpectedly large <span class="hlt">flux</span> loss observed in permanent <span class="hlt">magnets</span> in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual <span class="hlt">magnets</span> extracted from the relevant undulator have revealed that the <span class="hlt">flux</span> loss was caused by a homogeneous <span class="hlt">magnetization</span> reversal extending over a wide area, but not by demagnetization of individual <span class="hlt">magnets</span> damaged by radiation. We show that the estimated <span class="hlt">flux</span>-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the <span class="hlt">magnetization</span> reversal and quantify the <span class="hlt">flux</span> loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5126580','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5126580"><span>Radiation-induced <span class="hlt">magnetization</span> reversal causing a large <span class="hlt">flux</span> loss in undulator permanent <span class="hlt">magnets</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi</p> <p>2016-01-01</p> <p>We report an unexpectedly large <span class="hlt">flux</span> loss observed in permanent <span class="hlt">magnets</span> in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual <span class="hlt">magnets</span> extracted from the relevant undulator have revealed that the <span class="hlt">flux</span> loss was caused by a homogeneous <span class="hlt">magnetization</span> reversal extending over a wide area, but not by demagnetization of individual <span class="hlt">magnets</span> damaged by radiation. We show that the estimated <span class="hlt">flux</span>-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the <span class="hlt">magnetization</span> reversal and quantify the <span class="hlt">flux</span> loss are presented, together with possible countermeasures against rapid degradation of the undulator performance. PMID:27897218</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27897218','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27897218"><span>Radiation-induced <span class="hlt">magnetization</span> reversal causing a large <span class="hlt">flux</span> loss in undulator permanent <span class="hlt">magnets</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bizen, Teruhiko; Kinjo, Ryota; Hasegawa, Teruaki; Kagamihata, Akihiro; Kida, Yuichiro; Seike, Takamitsu; Watanabe, Takahiro; Hara, Toru; Itoga, Toshiro; Asano, Yoshihiro; Tanaka, Takashi</p> <p>2016-11-29</p> <p>We report an unexpectedly large <span class="hlt">flux</span> loss observed in permanent <span class="hlt">magnets</span> in one of the undulators operated in SACLA, the x-ray free electron laser facility in Japan. Characterizations of individual <span class="hlt">magnets</span> extracted from the relevant undulator have revealed that the <span class="hlt">flux</span> loss was caused by a homogeneous <span class="hlt">magnetization</span> reversal extending over a wide area, but not by demagnetization of individual <span class="hlt">magnets</span> damaged by radiation. We show that the estimated <span class="hlt">flux</span>-loss rate is much higher than what is reported in previous papers, and its distribution is much more localized to the upstream side. Results of numerical and experimental studies carried out to validate the <span class="hlt">magnetization</span> reversal and quantify the <span class="hlt">flux</span> loss are presented, together with possible countermeasures against rapid degradation of the undulator performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...839....9Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...839....9Z"><span>Solar Filament Longitudinal Oscillations along a <span class="hlt">Magnetic</span> Field <span class="hlt">Tube</span> with Two Dips</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Yu-Hao; Zhang, Li-Yue; Ouyang, Y.; Chen, P. F.; Fang, C.</p> <p>2017-04-01</p> <p>Large-amplitude longitudinal oscillations of solar filaments have been observed and explored for more than ten years. Previous studies are mainly based on the one-dimensional rigid <span class="hlt">flux</span> <span class="hlt">tube</span> model with a single <span class="hlt">magnetic</span> dip. However, it has been noted that there might be two <span class="hlt">magnetic</span> dips, and hence two threads, along one <span class="hlt">magnetic</span> field line. Following previous work, we intend to investigate the kinematics of the filament longitudinal oscillations when two threads are <span class="hlt">magnetically</span> connected, which is done by solving one-dimensional radiative hydrodynamic equations with the numerical code MPI-AMRVAC. Two different types of perturbations are considered, and the difference from previous works resulting from the interaction of the two filament threads is investigated. We find that even with the inclusion of the thread-thread interaction, the oscillation period is modified weakly, by at most 20% compared to the traditional pendulum model with one thread. However, the damping timescale is significantly affected by the thread-thread interaction. Hence, we should take it into account when applying the consistent seismology to the filaments where two threads are <span class="hlt">magnetically</span> connected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........93P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........93P"><span>Turbulent transport of fast ions due to <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Preiwisch, Adam</p> <p></p> <p>The transport of fast ions in <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in a laboratory plasma is studied. Strong perturbing <span class="hlt">flux</span> ropes (deltaE ~175 V/m, deltaB ~7 G) are generated by secondary cathode-anode pair at the upgraded LArge Plasma Device (LAPD). A 500-1000 eV lithium ion test beam is passed through the turbulent region and recollected by a gridded collimated analyzer, revealing enhanced fast ion broadening attributable to <span class="hlt">flux</span> rope perturbations. The broadening is observed to be well in excess of Coulomb scattering levels. Monte Carlo simulation is performed with model electrostatic and <span class="hlt">magnetic</span> fields, revealing negligible spreading as a result of the <span class="hlt">magnetic</span> perturbations. Modeled electrostatic perturbations are observed to broaden the beam by 3.0 mm2 at the closest recollection plane, increasing as the transit time squared further downstream. Transport attributed to electrostatic fluctuations has been shown to decrease with energy while <span class="hlt">magnetic</span> transport does not. Enhanced fast ion transport observed during the <span class="hlt">flux</span> rope off phase is presently unexplained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6117252','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6117252"><span>Miniature solenoid for the production of confined <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Walker, I.R.</p> <p>1984-11-01</p> <p>For experiments involving SQUID's it is sometimes desirable to have a small source of confined <span class="hlt">magnetic</span> field in order to provide a dc or RF <span class="hlt">flux</span> bias. This has been done by closely winding number50 AWG copper wire on a 250-..mu..m-diam optical fiber. The resulting solenoid is very small and has excellent mechanical and electrical properties at 4 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998SoPh..183...45G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998SoPh..183...45G"><span>On Analysis of Dual Spacecraft Stereoscopic Observations to Determine the Three-Dimensional Morphology and Plasma Properties of Solar Coronal <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gary, G. Allen; Davis, John M.; Moore, Ronald</p> <p>1998-11-01</p> <p>By using two spacecraft equipped with multi-bandpass X-ray telescopes, it is possible to obtain direct 3-dimensional morphology of coronal structures which is essential for understanding the energetics and dynamics of the solar atmosphere. X-ray observations taken only in orbit about the Earth are inadequate to fully resolve the 3-dimensional nature of the solar corona. These Earth-orbit observations produce 2-dimensional images and an appropriate model must be included to derive the 3-dimensional structures from the line-of-sight information. Stereoscopic observations from space will remove this limitation and are needed if we are to improve our knowledge of the 3-dimensional morphology of the corona. Several important points regarding a stereoscopic mission are investigated and illustrated using model coronal <span class="hlt">flux</span> <span class="hlt">tubes</span> and image-rendering techniques. Synthesized images are formed by integrating the emission from volume elements along the line-of-sight path through a 3-dimensional volume in which a set of model <span class="hlt">flux</span> <span class="hlt">tubes</span> are located. The <span class="hlt">flux</span> <span class="hlt">tubes</span> are defined by (1) a plasma model defining the emissivity for a specific density, temperature, and pressure distribution, and (2) a <span class="hlt">magnetic</span> field model from which a set of field lines are selected to define the geometry of the <span class="hlt">flux</span> <span class="hlt">tubes</span>. The field lines are used to define the <span class="hlt">flux-tube</span> volume by assuming an initial base radius and conservation of <span class="hlt">flux</span>. An effective instrumental spectral-response function is folded into the integration. Analysis of pairs of these synthesized images with various angular perspectives are used to investigate the effect of angular separation on mission objectives. The resulting images and analysis provide guidelines for developing a stereoscopic mission. Our study produced four important results, namely: (1) An angular separation of ~30 degrees maximizes the scientific return by direct triangulation analysis because of the tradeoff between increased line-of-sight resolution of position</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24g2710G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24g2710G"><span>Mass ablation and <span class="hlt">magnetic</span> <span class="hlt">flux</span> losses through a <span class="hlt">magnetized</span> plasma-liner wall interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>García-Rubio, F.; Sanz, J.</p> <p>2017-07-01</p> <p>The understanding of energy and <span class="hlt">magnetic</span> <span class="hlt">flux</span> losses in a <span class="hlt">magnetized</span> plasma medium confined by a cold wall is of great interest in the success of <span class="hlt">magnetized</span> liner inertial fusion (MagLIF). In a MagLIF scheme, the fuel is <span class="hlt">magnetized</span> and subsonically compressed by a cylindrical liner. <span class="hlt">Magnetic</span> <span class="hlt">flux</span> conservation is degraded by the presence of gradient-driven transport processes such as thermoelectric effects (Nernst) and <span class="hlt">magnetic</span> field diffusion. In previous publications [Velikovich et al., Phys. Plasmas 22, 042702 (2015)], the evolution of a hot <span class="hlt">magnetized</span> plasma in contact with a cold solid wall (liner) was studied using the classical collisional Braginskii's plasma transport equations in one dimension. The Nernst term degraded the <span class="hlt">magnetic</span> <span class="hlt">flux</span> conservation, while both thermal energy and <span class="hlt">magnetic</span> <span class="hlt">flux</span> losses were reduced with the electron Hall parameter ωeτe with a power-law asymptotic scaling (ωeτe)-1/2. In the analysis made in the present paper, we consider a similar situation, but with the liner being treated differently. Instead of a cold solid wall acting as a heat sink, we model the liner as a cold dense plasma with low thermal conduction (that could represent the cryogenic fuel layer added on the inner surface of the liner in a high-gain MagLIF configuration). Mass ablation comes into play, which adds notably differences to the previous analysis. The direction of the plasma motion is inverted, but the Nernst term still convects the <span class="hlt">magnetic</span> field towards the liner. <span class="hlt">Magnetization</span> suppresses the Nernst velocity and improves the <span class="hlt">magnetic</span> <span class="hlt">flux</span> conservation. Thermal energy in the hot plasma is lost in heating the ablated material. When the electron Hall parameter is large, mass ablation scales as (ωeτe)-3/10, while both the energy and <span class="hlt">magnetic</span> <span class="hlt">flux</span> losses are reduced with a power-law asymptotic scaling (ωeτe)-7/10.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BTSNU..51...39T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BTSNU..51...39T"><span>On the <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Conservation in the Partially Ionzied Plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsap, Yu.; Kopylova, Yu.</p> <p>2014-12-01</p> <p>The Ohm, Hall, and ambipolar diffusions in the partially ionized plasma are considered. It has been shown that the statement of Pandey and Wardle that only the Ohm diffusion is capable to decrease the <span class="hlt">magnetic</span> <span class="hlt">flux</span> is not sufficiently correct due to the formal dependence of the <span class="hlt">magnetic</span> diffusion on a selected frame of reference. Thes ignificance of understanding of the physical nature for the dissipation and diffusion of the <span class="hlt">magnetic</span> field in the partially ionized plasma as well as consequences of obtained results are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPD....4840606T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPD....4840606T"><span>Regularized Biot-Savart Laws for Modeling <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Titov, Viacheslav; Downs, Cooper; Mikic, Zoran; Torok, Tibor; Linker, Jon A.</p> <p>2017-08-01</p> <p>Many existing models assume that <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes play a key role in solar flares and coronal mass ejections (CMEs). It is therefore important to develop efficient methods for constructing <span class="hlt">flux</span>-rope configurations constrained by observed <span class="hlt">magnetic</span> data and the initial morphology of CMEs. As our new step in this direction, we have derived and implemented a compact analytical form that represents the <span class="hlt">magnetic</span> field of a thin <span class="hlt">flux</span> rope with an axis of arbitrary shape and a circular cross-section. This form implies that the <span class="hlt">flux</span> rope carries axial current I and axial <span class="hlt">flux</span> F, so that the respective <span class="hlt">magnetic</span> field is a curl of the sum of toroidal and poloidal vector potentials proportional to I and F, respectively. The vector potentials are expressed in terms of Biot-Savart laws whose kernels are regularized at the rope axis. We regularized them in such a way that for a straight-line axis the form provides a cylindrical force-free <span class="hlt">flux</span> rope with a parabolic profile of the axial current density. So far, we set the shape of the rope axis by tracking the polarity inversion lines of observed magnetograms and estimating its height and other parameters of the rope from a calculated potential field above these lines. In spite of this heuristic approach, we were able to successfully construct pre-eruption configurations for the 2009 February13 and 2011 October 1 CME events. These applications demonstrate that our regularized Biot-Savart laws are indeed a very flexible and efficient method for energizing initial configurations in MHD simulations of CMEs. We discuss possible ways of optimizing the axis paths and other extensions of the method in order to make it more useful and robust.Research supported by NSF, NASA's HSR and LWS Programs, and AFOSR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22486409','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22486409"><span>Frozen <span class="hlt">flux</span> violation, electron demagnetization and <span class="hlt">magnetic</span> reconnection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scudder, J. D.; Karimabadi, H.; Roytershteyn, V.; Daughton, W.</p> <p>2015-10-15</p> <p>We argue that the analogue in collisionless plasma of the collisional diffusion region of <span class="hlt">magnetic</span> reconnection is properly defined in terms of the demagnetization of the plasma electrons that enable “frozen flux” slippage to occur. This condition differs from the violation of the “frozen-in” condition, which only implies that two fluid effects are involved, rather than the necessary slippage of <span class="hlt">magnetic</span> <span class="hlt">flux</span> as viewed in the electron frame. Using 2D Particle In Cell (PIC) simulations, this approach properly finds the saddle point region of the <span class="hlt">flux</span> function. Our demagnetization conditions are the dimensionless guiding center approximation expansion parameters for electrons which we show are observable and determined locally by the ratio of non-ideal electric to <span class="hlt">magnetic</span> field strengths. Proxies for frozen <span class="hlt">flux</span> slippage are developed that (a) are measurable on a single spacecraft, (b) are dimensionless with theoretically justified threshold values of significance, and (c) are shown in 2D simulations to recover distinctions theoretically possible with the (unmeasurable) <span class="hlt">flux</span> function. A new potentially observable dimensionless frozen <span class="hlt">flux</span> rate, Λ{sub Φ}, differentiates significant from anecdotal frozen <span class="hlt">flux</span> slippage. A single spacecraft observable, ϒ, is shown with PIC simulations to be essentially proportional to the unobservable local Maxwell frozen <span class="hlt">flux</span> rate. This relationship theoretically establishes electron demagnetization in 3D as the general cause of frozen <span class="hlt">flux</span> slippage. In simple 2D cases with an isolated central diffusion region surrounded by separatrices, these diagnostics uniquely identify the traditional diffusion region (without confusing it with the two fluid “ion-diffusion” region) and clarify the role of the separatrices where frozen <span class="hlt">flux</span> violations do occur but are not substantial. In the more complicated guide and asymmetric 2D cases, substantial <span class="hlt">flux</span> slippage regions extend out along, but inside of, the preferred separatrices</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPCO8007M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPCO8007M"><span>Direct measurement of <span class="hlt">magnetic</span> <span class="hlt">flux</span> compression on the Z pulsed-power accelerator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McBride, R. D.; Bliss, D. E.; Martin, M. R.; Jennings, C. A.; Lamppa, D. C.; Dolan, D. H.; Lemke, R. W.; Rovang, D. C.; Rochau, G. A.; Cuneo, M. E.; Sinars, D. B.; Intrator, T. P.; Weber, T. E.</p> <p>2016-10-01</p> <p>We report on the progress made to date for directly measuring <span class="hlt">magnetic</span> <span class="hlt">flux</span> compression on Z. Each experiment consisted of an initially solid aluminum liner (a cylindrical <span class="hlt">tube</span>), which was imploded using Z's drive current (0-20 MA in 100 ns). The imploding liner compresses a 10-20-T axial seed field, Bz(0), supplied by an independently driven Helmholtz coil pair. Assuming perfect <span class="hlt">flux</span> conservation, the axial field amplification should be well described by Bz(t) =Bz (0)×[R(0)/R(t)]2, where R is the liner's inner surface radius. With perfect <span class="hlt">flux</span> conservation, Bz and dBz/dt values exceeding 104 T and 1012 T/s, respectively, are expected. These large values, the diminishing liner volume, and the harsh environment on Z, make it particularly challenging to measure these fields directly. We report on our latest efforts to do so using a fiber-optic-based Faraday rotation diagnostic, where the magneto-active portion of the sensor is made from terbium-doped optical fiber. We have now used this diagnostic to measure a <span class="hlt">flux</span>-compressed <span class="hlt">magnetic</span> field to over 600 T prior to the imploding liner hitting the on-axis fiber housing. This project was funded in part by Sandia's LDRD program and US DOE-NNSA contract DE-AC04-94AL85000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50KLT01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50KLT01M"><span>Minnealloy: a new <span class="hlt">magnetic</span> material with high saturation <span class="hlt">flux</span> density and low <span class="hlt">magnetic</span> anisotropy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mehedi, Md; Jiang, Yanfeng; Suri, Pranav Kumar; Flannigan, David J.; Wang, Jian-Ping</p> <p>2017-09-01</p> <p>We are reporting a new soft <span class="hlt">magnetic</span> material with high saturation <span class="hlt">magnetic</span> <span class="hlt">flux</span> density, and low <span class="hlt">magnetic</span> anisotropy. The new material is a compound of iron, nitrogen and carbon, α‧-Fe8(NC), which has saturation <span class="hlt">flux</span> density of 2.8  ±  0.15 T and <span class="hlt">magnetic</span> anisotropy of 46 kJ m-3. The saturation <span class="hlt">flux</span> density is 27% higher than pure iron, a widely used soft <span class="hlt">magnetic</span> material. Soft <span class="hlt">magnetic</span> materials are very important building blocks of motors, generators, inductors, transformers, sensors and write heads of hard disk. The new material will help in the miniaturization and efficiency increment of the next generation of electronic devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7234233','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7234233"><span>Plasmas <span class="hlt">fluxes</span> to surfaces for an oblique <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pitcher, C.S. ); Stangeby, P.C.; Elder, J.D. ); Bell, M.G.; Kilpatrick, S.J.; Manos, D.M.; Medley, S.S.; Owens, D.K.; Ramsey, A.T.; Ulrickson, M. . Plasma Physics Lab.)</p> <p>1992-07-01</p> <p>The poloidal and toroidal spatial distributions of D{sub {alpha}}, He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface. The distributions are found not to agree with a model (the Cosine'' model) which determines the incident <span class="hlt">flux</span> density using only the parallel <span class="hlt">fluxes</span> in the scrape-off layer and the projected area of the surface perpendicular to the field lines. In particular, the Cosine model is not able to explain the significant <span class="hlt">fluxes</span> observed at locations on the surface which are oblique to the <span class="hlt">magnetic</span> field. It is further shown that these <span class="hlt">fluxes</span> cannot be explained by the finite Larmor radius of impinging ions. Finally, it is demonstrated, with the use of Monte Carlo codes, that the distributions can be explained by including both parallel and cross-field transport onto the limiter surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10166895','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10166895"><span>Plasmas <span class="hlt">fluxes</span> to surfaces for an oblique <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pitcher, C.S.; Stangeby, P.C.; Elder, J.D.; Bell, M.G.; Kilpatrick, S.J.; Manos, D.M.; Medley, S.S.; Owens, D.K.; Ramsey, A.T.; Ulrickson, M.</p> <p>1992-07-01</p> <p>The poloidal and toroidal spatial distributions of D{sub {alpha}}, He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface. The distributions are found not to agree with a model (the ``Cosine`` model) which determines the incident <span class="hlt">flux</span> density using only the parallel <span class="hlt">fluxes</span> in the scrape-off layer and the projected area of the surface perpendicular to the field lines. In particular, the Cosine model is not able to explain the significant <span class="hlt">fluxes</span> observed at locations on the surface which are oblique to the <span class="hlt">magnetic</span> field. It is further shown that these <span class="hlt">fluxes</span> cannot be explained by the finite Larmor radius of impinging ions. Finally, it is demonstrated, with the use of Monte Carlo codes, that the distributions can be explained by including both parallel and cross-field transport onto the limiter surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940031338','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940031338"><span>Materials for efficient high-<span class="hlt">flux</span> <span class="hlt">magnetic</span> bearing actuators</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Williams, M. E.; Trumper, D. L.</p> <p>1994-01-01</p> <p><span class="hlt">Magnetic</span> bearings have demonstrated the capability for achieving positioning accuracies at the nanometer level in precision motion control stages. This makes possible the positioning of a wafer in six degrees of freedom with the precision necessary for photolithography. To control the position of an object at the nanometer level, a model of the <span class="hlt">magnetic</span> bearing actuator force-current-airgap relationship must be accurately obtained. Additionally, to reduce thermal effects the design of the actuator should be optimized to achieve maximum power efficiency and <span class="hlt">flux</span> density. Optimization of the actuator is accomplished by proper pole face sizing and utilizing a <span class="hlt">magnetic</span> core material which can be <span class="hlt">magnetized</span> to the highest <span class="hlt">flux</span> density with low <span class="hlt">magnetic</span> loss properties. This paper describes the construction of a <span class="hlt">magnetic</span> bearing calibration fixture designed for experimental measurement of the actuator force characteristics. The results of a material study that review the force properties of nickel-steel, silicon-steel, and cobalt-vanadium-iron, as they apply to <span class="hlt">magnetic</span> bearing applications are also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000PhyC..341.1289T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000PhyC..341.1289T"><span><span class="hlt">Flux</span> line depinning in a <span class="hlt">magnet</span>-superconductor levitation system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Terentiev, A. N.; Hull, J. R.; De Long, L. E.</p> <p></p> <p>The AC loss characteristics of a <span class="hlt">magnet</span>-superconductor system were studied with the <span class="hlt">magnet</span> fixed to the free end of an oscillating cantilever located near a stationary melt-textured YBCO pellet. Below a threshold AC field amplitude ≈2 Oe, the dissipation of the oscillator is amplitude-independent, characteristic of a linear, non-hysteretic regime. Above threshold, dissipation increases with amplitude, reflecting the depinning and hysteretic motion of <span class="hlt">flux</span> lines. The threshold AC field is an order of magnitude higher than that measured for the same YBCO material via AC susceptometry in a uniform DC <span class="hlt">magnetic</span> field. A partial lock-in of <span class="hlt">flux</span> lines between YBCO ab planes is proposed as the mechanism for the substantial increase of the depinning threshold.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860017603','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860017603"><span>In situ measurements of the plasma bulk velocity near the Io <span class="hlt">flux</span> <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barnett, A.</p> <p>1985-01-01</p> <p>The flow around the Io <span class="hlt">flux</span> <span class="hlt">tube</span> was studied by analyzing the eleven spectra taken by the Voyager 1 Plasma Science (PLS) experiment in its vicinity. The bulk plasma parameters were determined using a procedure that uses the full response function of the instrument and the data in all four PLS sensors. The mass density of the plasma in the vicinity of Io is found to be 22,500 + or - 2,500 amu/cu cm and its electron density is found to be 1500 + or - 200/cu cm. The Alfven speed was determined using three independent methods; the values obtained are consistent and taken together yield V sub A = 300 + or - 50 km/sec, corresponding to an Alfven Mach number of 0.19 + or - 0.02. For the flow pattern, good agreement was found with the model of Neubauer (1980), and it was concluded that the plasma flows around the <span class="hlt">flux</span> <span class="hlt">tube</span> with a pattern similar to the flow of an incompressible fluid around a long cylinder obstacle of radius 1.26 + or - 0.1 R sub Io.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1360021-event-event-study-space-time-dynamics-flux-tube-fragmentation','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1360021-event-event-study-space-time-dynamics-flux-tube-fragmentation"><span>Event-by-Event Study of Space-Time Dynamics in <span class="hlt">Flux-Tube</span> Fragmentation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Wong, Cheuk-Yin</p> <p>2017-05-25</p> <p>In the semi-classical description of the <span class="hlt">flux-tube</span> fragmentation process for hadron production and hadronization in high-energymore » $e^+e^-$ annihilations and $pp$ collisions, the rapidity-space-time ordering and the local conservation laws of charge, flavor, and momentum provide a set of powerful tools that may allow the reconstruction of the space-time dynamics of quarks and mesons in exclusive measurements of produced hadrons, on an event-by-event basis. We propose procedures to reconstruct the space-time dynamics from event-by-event exclusive hadron data to exhibit explicitly the ordered chain of hadrons produced in a <span class="hlt">flux</span> <span class="hlt">tube</span> fragmentation. As a supplementary tool, we infer the average space-time coordinates of the $q$-$$\\bar q$$ pair production vertices from the $$\\pi^-$$ rapidity distribution data obtained by the NA61/SHINE Collaboration in $pp$ collisions at $$\\sqrt{s}$$ = 6.3 to 17.3 GeV.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25370658','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25370658"><span>Electrostatic focal spot correction for x-ray <span class="hlt">tubes</span> operating in strong <span class="hlt">magnetic</span> fields.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca</p> <p>2014-11-01</p> <p> orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray <span class="hlt">tube</span> by 30° toward the MR bore increases the parallel <span class="hlt">magnetic</span> field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output <span class="hlt">flux</span> is reduced by 7.5%. The maximum orthogonal <span class="hlt">magnetic</span> field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray <span class="hlt">tube</span> insert. The electrostatic approach also suffers from limitations when there are strong <span class="hlt">magnetic</span> fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel <span class="hlt">magnetic</span> field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4209011','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4209011"><span>Electrostatic focal spot correction for x-ray <span class="hlt">tubes</span> operating in strong <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo; Fahrig, Rebecca</p> <p>2014-01-01</p> <p> field in addition to the orthogonal field does not affect the electrostatic correction technique. However, rotation of the x-ray <span class="hlt">tube</span> by 30° toward the MR bore increases the parallel <span class="hlt">magnetic</span> field magnitude (∼72 mT). The presence of this larger parallel field along with the orthogonal field leads to incomplete correction. Monte Carlo simulations demonstrate that the mean energy of the x-ray spectrum is not noticeably affected by the electrostatic correction, but the output <span class="hlt">flux</span> is reduced by 7.5%. Conclusions: The maximum orthogonal <span class="hlt">magnetic</span> field magnitude that can be compensated for using the proposed design is 65 mT. Larger orthogonal field magnitudes cannot be completely compensated for because a pure electrostatic approach is limited by the dielectric strength of the vacuum inside the x-ray <span class="hlt">tube</span> insert. The electrostatic approach also suffers from limitations when there are strong <span class="hlt">magnetic</span> fields in both the orthogonal and parallel directions because the electrons prefer to stay aligned with the parallel <span class="hlt">magnetic</span> field. These challenging field conditions can be addressed by using a hybrid correction approach that utilizes both active shielding coils and biasing electrodes. PMID:25370658</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10168361','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10168361"><span>Columbia University flow instability experimental program: Volume 7. Single <span class="hlt">tube</span> tests, critical heat <span class="hlt">flux</span> test program</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dougherty, T.; Maciuca, C.; McAssey, E.V. Jr.; Reddy, D.G.; Yang, B.W.</p> <p>1992-09-01</p> <p>This report deals with critical heat <span class="hlt">flux</span> (CHF) measurements in vertical down flow of water at low pressures in a round Inconel <span class="hlt">tube</span>, 96 inches long and 0.62 inch inside diameter. A total of 28 CHF points were obtained. These data were found to correlate linearly with the single variable q, defined as the heat <span class="hlt">flux</span> required to raise the enthalpy from the inlet value to the saturation value. These results were compared to the published results of Swedish investigators for vertical upflow of water at low pressures in round <span class="hlt">tubes</span> of similar diameters and various lengths. The parameter q depends on the inlet enthalpy and is a nonlocal variable, thus this correlation is nonlocal unless the coefficients depend upon <span class="hlt">tube</span> length in a particular prescribed manner. For the low pressure Swedish data, the coefficients are practically independent of length and hence the correlation is nonlocal. In the present investigation only one length was employed, so it is not possible to determine whether the correlation for these data is local or nonlocal, although there is reason to believe that it is local. The same correlation was applied to a large data base (thousands of CHF points) compiled from the published data of a number of groups and found to apply, with reasonable accuracy over a wide range of conditions, yielding sometimes local and sometimes nonlocal correlations. The basic philosophy of data analysis here was not to generate a single correlation which would reproduce all data, but to search for correlations which apply adequately over some range and which might have some mechanistic significance. The tentative conclusion is that at least two mechanisms appear operative, leading to two types of correlations, one local, the other nonlocal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1338611','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1338611"><span>Quasi-static and dynamic <span class="hlt">magnetic</span> tension forces in arched, line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Myers, C. E.; Yamada, M.; Ji, H.; Yoo, J.; Jara-Almonte, J.; Fox, W.</p> <p>2016-11-22</p> <p>Solar eruptions are often driven by magnetohydrodynamic instabilities such as the torus and kink instabilities that act on line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. We designed our recent laboratory experiments to study these eruptive instabilities which have demonstrated the key role of both dynamic (Myers et al 2015 Nature 528 526) and quasi-static (Myers et al 2016 Phys. Plasmas 23 112102) <span class="hlt">magnetic</span> tension forces in contributing to the equilibrium and stability of line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. In our paper, we synthesize these laboratory results and explore the relationship between the dynamic and quasi-static tension forces. And while the quasi-static tension force is found to contribute to the <span class="hlt">flux</span> rope equilibrium in a number of regimes, the dynamic tension force is substantial mostly in the so-called failed torus regime where <span class="hlt">magnetic</span> self-organization events prevent the <span class="hlt">flux</span> rope from erupting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1338611-quasi-static-dynamic-magnetic-tension-forces-arched-line-tied-magnetic-flux-ropes','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1338611-quasi-static-dynamic-magnetic-tension-forces-arched-line-tied-magnetic-flux-ropes"><span>Quasi-static and dynamic <span class="hlt">magnetic</span> tension forces in arched, line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Myers, C. E.; Yamada, M.; Ji, H.; ...</p> <p>2016-11-22</p> <p>Solar eruptions are often driven by magnetohydrodynamic instabilities such as the torus and kink instabilities that act on line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. We designed our recent laboratory experiments to study these eruptive instabilities which have demonstrated the key role of both dynamic (Myers et al 2015 Nature 528 526) and quasi-static (Myers et al 2016 Phys. Plasmas 23 112102) <span class="hlt">magnetic</span> tension forces in contributing to the equilibrium and stability of line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. In our paper, we synthesize these laboratory results and explore the relationship between the dynamic and quasi-static tension forces. And while the quasi-static tension force ismore » found to contribute to the <span class="hlt">flux</span> rope equilibrium in a number of regimes, the dynamic tension force is substantial mostly in the so-called failed torus regime where <span class="hlt">magnetic</span> self-organization events prevent the <span class="hlt">flux</span> rope from erupting.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PPCF...59a4048M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PPCF...59a4048M"><span>Quasi-static and dynamic <span class="hlt">magnetic</span> tension forces in arched, line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Myers, C. E.; Yamada, M.; Ji, H.; Yoo, J.; Jara-Almonte, J.; Fox, W.</p> <p>2017-01-01</p> <p>Solar eruptions are often driven by magnetohydrodynamic instabilities such as the torus and kink instabilities that act on line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. Recent laboratory experiments designed to study these eruptive instabilities have demonstrated the key role of both dynamic (Myers et al 2015 Nature 528 526) and quasi-static (Myers et al 2016 Phys. Plasmas 23 112102) <span class="hlt">magnetic</span> tension forces in contributing to the equilibrium and stability of line-tied <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes. In this paper, we synthesize these laboratory results and explore the relationship between the dynamic and quasi-static tension forces. While the quasi-static tension force is found to contribute to the <span class="hlt">flux</span> rope equilibrium in a number of regimes, the dynamic tension force is substantial mostly in the so-called failed torus regime where <span class="hlt">magnetic</span> self-organization events prevent the <span class="hlt">flux</span> rope from erupting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6937740','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6937740"><span>MHD-instability of a drop of <span class="hlt">magnetic</span> fluid in a circular capillary <span class="hlt">tube</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tsebers, A.O.</p> <p>1987-10-01</p> <p>The authors theoretically assess the magnetohydrodynamic kink instability of a droplet of <span class="hlt">magnetic</span> liquid under film and capillary flow conditions in a <span class="hlt">tube</span> in the presence of a transverse <span class="hlt">magnetic</span> field and affected by flexural deformation. The film and <span class="hlt">tube</span> are considered to be infinitely long. Introducing the surface tensions of the liquid-vapor boundary, the liquid-<span class="hlt">tube</span> wall boundary, and the vapor-<span class="hlt">tube</span> wall boundary, the film surface contribution to the total energy of the system is represented, and the threshold value of <span class="hlt">magnetization</span> necessary for the development of flexural deformation is determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890001456','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890001456"><span>C 4 <span class="hlt">fluxes</span> from the sun as a star and the correlation with <span class="hlt">magnetic</span> <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schrijver, C. J.; Linsky, J. L.; Bennett, J.; Brown, A.; Saar, S. H.</p> <p>1988-01-01</p> <p>A total of 144 C 4 wavelength 1548 SMM-UVSP spectroheliograms of solar plages were analyzed, some of which are series of exposures of the same region on the same day. Also analyzed were C 4 wavelength 1551 rasters of plages and C 4 1548 rasters of the quiet sun. The sample contains data on 17 different plages, observed on 50 different days. The center-to-limb variations of the active regions show that the optical thickness effects in the C 4 wavelength 1548 line can be neglected in the conversion from intensity to <span class="hlt">flux</span> density. As expected for the nearly optically thin situation, the C 4 1548 line is twice as bright as the C 4 wavelength 1551 line. The average C 4 wavelength 1548 <span class="hlt">flux</span> density for a quiet is 2700 erg/cm/s and, with surprisingly little scatter, 18,000 erg/cm/s for plages. The intensity histograms of rasters obtained at disk centers can be separated into characteristic plage and quiet-sun contributions with variable relative filling factors. The disk-averaged <span class="hlt">flux</span> density in the C 4 doublet and the disk-averaged magnitude of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> density are related. The relationship between the C 4 and <span class="hlt">magnetic</span> <span class="hlt">flux</span> densities for spatially resolved data is inferred to be almost the same, with only an additional factor of order unity in the constant of proportionality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002mwoc.conf...39M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002mwoc.conf...39M"><span>Contagious Coronal Heating from Recurring Emergence of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moore, R. L.; Falconer, D. A.; Sterling, A. C.</p> <p>2002-01-01</p> <p>For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence within the old bipole. The observations show: 1. In each active region, new <span class="hlt">flux</span> emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the <span class="hlt">flux</span> emergence. 4. There are episodes of enhanced coronal heating in surrounding <span class="hlt">magnetic</span> fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged <span class="hlt">flux</span> within an old active region entails far reaching adjustments in the 3D <span class="hlt">magnetic</span> field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We Also Note That The Reason For The recurrence of <span class="hlt">flux</span> emergence in old active regions may be that active-region <span class="hlt">flux</span> tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020022350&hterms=emergen+technology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Demergen*%2Btechnology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020022350&hterms=emergen+technology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Demergen*%2Btechnology"><span>Contagious Coronal Heating from Recurring Emergence of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)</p> <p>2001-01-01</p> <p>For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new <span class="hlt">magnetic</span> <span class="hlt">flux</span> emerge= within the old bipole. The observations show: 1. In each active region, new <span class="hlt">flux</span> emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the <span class="hlt">flux</span> emergence. 4. There are episodes of enhanced coronal heating in surrounding <span class="hlt">magnetic</span> fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged <span class="hlt">flux</span> within an old active region entails far reaching adjustments in the 3D <span class="hlt">magnetic</span> field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of <span class="hlt">flux</span> emergence in old active regions may be that active region <span class="hlt">flux</span> tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020022350&hterms=Emergence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DEmergence','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020022350&hterms=Emergence&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DEmergence"><span>Contagious Coronal Heating from Recurring Emergence of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)</p> <p>2001-01-01</p> <p>For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new <span class="hlt">magnetic</span> <span class="hlt">flux</span> emerge= within the old bipole. The observations show: 1. In each active region, new <span class="hlt">flux</span> emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the <span class="hlt">flux</span> emergence. 4. There are episodes of enhanced coronal heating in surrounding <span class="hlt">magnetic</span> fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged <span class="hlt">flux</span> within an old active region entails far reaching adjustments in the 3D <span class="hlt">magnetic</span> field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of <span class="hlt">flux</span> emergence in old active regions may be that active region <span class="hlt">flux</span> tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992SoPh..138...69H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992SoPh..138...69H"><span>Vector magnetogram and dopplergram observation of <span class="hlt">magnetic</span> <span class="hlt">flux</span> emergence and its explanation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hongqi, Zhang; Mutao, Song</p> <p>1992-03-01</p> <p>During 23 28 August 1988, at the Huairou Solar Observation Station of Beijing Observatory, the full development process of the region HR 88059 was observed. It emerged near the center of the solar disk and formed a medium active region. A complete series of vector magnetograms and photospheric and chromospheric Dopplergrams was obtained. From an analysis of these data, combined with some numerical simulations, the following conclusions can be drawn. (1) The emergence of new <span class="hlt">magnetic</span> <span class="hlt">flux</span> from enhanced networks followed by sunspot formation is an interesting physical process which can be simply described by MHD numerical simulation. The phenomena accompanying it occur according to a definite law summarized by Zwaan (1985). The condition for gas cooling and sunspot formation seems to be transverse field strength > 50 G together with longitudinal field strength > 700 G. For a period of 4 to 5 hours, the orientation of the transverse field shows little change. The configuration of field lines may be derived from vector magnetograms. The arch filament system can be recognized as an MHD shock. (2) New opposite bipolar features emerge within the former bipolar field with an identical strength which will develop a sunspot group complex. Also, arch filament systems appear there located in the position of <span class="hlt">flux</span> emergence. The neutral line is often pushed aside and curved, leading to faculae heating and the formation of a current sheet. In spite of complicated Dopplergrams, the same phenomena occur at the site of <span class="hlt">flux</span> emergence as usual: upward flow appears at the location of the emerging and rapidly varying <span class="hlt">flux</span> near the <span class="hlt">magnetic</span> neutral line, and downdraft occurs over large parts of the legs of the emerging <span class="hlt">flux</span> <span class="hlt">tubes</span>. The age of <span class="hlt">magnetic</span> emerging <span class="hlt">flux</span> (or a sunspot) can be estimated in terms of transverse field strengths: when 50 G < transverse field < 200 G, the longitudinal magnetogram and Dopplergram change rapidly, which indicates a rigourously emerging <span class="hlt">magnetic</span> <span class="hlt">flux</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25167026','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25167026"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> noise in dc SQUIDs: temperature and geometry dependence.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anton, S M; Birenbaum, J S; O'Kelley, S R; Bolkhovsky, V; Braje, D A; Fitch, G; Neeley, M; Hilton, G C; Cho, H-M; Irwin, K D; Wellstood, F C; Oliver, W D; Shnirman, A; Clarke, John</p> <p>2013-04-05</p> <p>The spectral density S(Φ)(f) = A(2)/(f/1 Hz)(α) of <span class="hlt">magnetic</span> <span class="hlt">flux</span> noise in ten dc superconducting quantum interference devices (SQUIDs) with systematically varied geometries shows that α increases as the temperature is lowered; in so doing, each spectrum pivots about a nearly constant frequency. The mean-square <span class="hlt">flux</span> noise, inferred by integrating the power spectra, grows rapidly with temperature and at a given temperature is approximately independent of the outer dimension of a given SQUID. These results are incompatible with a model based on the random reversal of independent, surface spins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22518699','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22518699"><span><span class="hlt">MAGNETIC</span> <span class="hlt">FLUX</span> CONSERVATION IN THE HELIOSHEATH INCLUDING SOLAR CYCLE VARIATIONS OF <span class="hlt">MAGNETIC</span> FIELD INTENSITY</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Michael, A. T.; Opher, M.; Provornikova, E.; Richardson, J. D.; Tóth, G. E-mail: mopher@bu.edu E-mail: jdr@space.mit.edu</p> <p>2015-04-10</p> <p>In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and <span class="hlt">magnetic</span> <span class="hlt">flux</span> conservation. Voyager 1, however, has observed a decrease in the flow’s radial velocity and an order of magnitude decrease in <span class="hlt">magnetic</span> <span class="hlt">flux</span>. We investigate the role of the 11 yr solar cycle variation of the <span class="hlt">magnetic</span> field strength on the <span class="hlt">magnetic</span> <span class="hlt">flux</span> within the HS using a global 3D magnetohydrodynamic model of the heliosphere. We use time and latitude-dependent solar wind velocity and density inferred from Solar and Heliospheric Observatory/SWAN and interplanetary scintillations data and implemented solar cycle variations of the <span class="hlt">magnetic</span> field derived from 27 day averages of the field magnitude average of the <span class="hlt">magnetic</span> field at 1 AU from the OMNI database. With the inclusion of the solar cycle time-dependent <span class="hlt">magnetic</span> field intensity, the model matches the observed intensity of the <span class="hlt">magnetic</span> field in the HS along both Voyager 1 and 2. This is a significant improvement from the same model without <span class="hlt">magnetic</span> field solar cycle variations, which was over a factor of two larger. The model accurately predicts the radial velocity observed by Voyager 2; however, the model predicts a flow speed ∼100 km s{sup −1} larger than that derived from LECP measurements at Voyager 1. In the model, <span class="hlt">magnetic</span> <span class="hlt">flux</span> is conserved along both Voyager trajectories, contrary to observations. This implies that the solar cycle variations in solar wind <span class="hlt">magnetic</span> field observed at 1 AU does not cause the order of magnitude decrease in <span class="hlt">magnetic</span> <span class="hlt">flux</span> observed in the Voyager 1 data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27869864','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27869864"><span>Photomultiplier <span class="hlt">tube</span> calibration based on Na lidar observation and its effect on heat <span class="hlt">flux</span> bias.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Alan Z; Guo, Yafang</p> <p>2016-11-20</p> <p>Na lidar can measure vertical wind and temperature at high temporal and vertical resolutions, enough to resolve gravity wave perturbations. Heat <span class="hlt">flux</span> due to dissipating gravity waves is an important quantity that can be derived from such perturbations. When lidar signals are high, a photomultiplier <span class="hlt">tube</span> (PMT) used to count incoming photons may suffer from the saturation effect, and its output count is not linearly related to incoming photon counts. Corrections to this effect can be measured in a laboratory setting but may have large errors at high count rates. We show that the errors in the PMT correction can cause significant bias in the heat <span class="hlt">flux</span> calculation due to the inherent correlation between wind and temperature errors. Using the measurements made by Na lidar at the Andes Lidar Observatory with Hamamatsu PMTs, we developed a calibration procedure to remove such PMT correction errors from laboratory measurements. By applying the revised PMT correction curve we demonstrated that the heat <span class="hlt">flux</span> bias can be removed through this procedure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SoPh..200..115H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SoPh..200..115H"><span>Catastrophe of coronal <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes in partially open <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Y. Q.</p> <p>2001-05-01</p> <p>Using a 2.5-D, time-dependent ideal MHD model in Cartesian coordinates, a numerical study is carried out to find equilibrium solutions associated with a <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope in the corona. The ambient <span class="hlt">magnetic</span> field is partially open, consisting of a closed arcade in the center and an open field at the flank. The coronal <span class="hlt">magnetic</span> <span class="hlt">flux</span> rope is characterized by its <span class="hlt">magnetic</span> properties, including the axial and annular <span class="hlt">magnetic</span> <span class="hlt">fluxes</span> and the <span class="hlt">magnetic</span> helicity, and its geometrical features, including the height of the rope axis, the halfwidth of the rope and the length of the vertical current sheet below the rope. It is shown that for a given partially open ambient <span class="hlt">magnetic</span> field, the dependence of the geometrical features on the <span class="hlt">magnetic</span> properties displays a catastrophic behavior, namely, there exists a certain critical point, across which an infinitesimal enhancement of the <span class="hlt">magnetic</span> parameters causes a finite jump of the geometrical parameters for the rope. The amplitude of the jump depends on the extent to which the ambient <span class="hlt">magnetic</span> field in open, and approaches to zero when the ambient <span class="hlt">magnetic</span> field becomes completely closed. The implication of such a catastrophe in solar active phenomena is briefly discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000065622','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000065622"><span><span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Compression Concept for Aerospace Propulsion and Power</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Litchford, Ron J.; Robertson, Tony; Hawk, Clark W.; Turner, Matt; Koelfgen, Syri</p> <p>2000-01-01</p> <p>The objective of this research is to investigate system level performance and design issues associated with <span class="hlt">magnetic</span> <span class="hlt">flux</span> compression devices for aerospace power generation and propulsion. The proposed concept incorporates the principles of <span class="hlt">magnetic</span> <span class="hlt">flux</span> compression for direct conversion of nuclear/chemical detonation energy into electrical power. Specifically a <span class="hlt">magnetic</span> field is compressed between an expanding detonation driven diamagnetic plasma and a stator structure formed from a high temperature superconductor (HTSC). The expanding plasma cloud is entirely confined by the compressed <span class="hlt">magnetic</span> field at the expense of internal kinetic energy. Electrical power is inductively extracted, and the detonation products are collimated and expelled through a <span class="hlt">magnetic</span> nozzle. The long-term development of this highly integrated generator/propulsion system opens up revolutionary NASA Mission scenarios for future interplanetary and interstellar spacecraft. The unique features of this concept with respect to future space travel opportunities are as follows: ability to implement high energy density chemical detonations or ICF microfusion bursts as the impulsive diamagnetic plasma source; high power density system characteristics constrain the size, weight, and cost of the vehicle architecture; provides inductive storage pulse power with a very short pulse rise time; multimegajoule energy bursts/terawatt power bursts; compact pulse power driver for low-impedance dense plasma devices; utilization of low cost HTSC material and casting technology to increase <span class="hlt">magnetic</span> <span class="hlt">flux</span> conservation and inductive energy storage; improvement in chemical/nuclear-to-electric energy conversion efficiency and the ability to generate significant levels of thrust with very high specific impulse; potential for developing a small, lightweight, low cost, self-excited integrated propulsion and power system suitable for space stations, planetary bases, and interplanetary and interstellar space travel</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM51A2560N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM51A2560N"><span>Possible Properties of Kinetic <span class="hlt">Flux</span> Ropes Generated by <span class="hlt">Magnetic</span> Reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ng, C. S.</p> <p>2015-12-01</p> <p>We present latest results of numerical studies of a recently obtained analytic solution that can describe small-scale kinetic <span class="hlt">flux</span> ropes. Such exact nonlinear solution of the Vlasov-Poisson-Ampere system of equations can be regarded as two-dimensional Bernstein-Greene-Kruskal (BGK) mode, generalizing from a solution in a <span class="hlt">magnetized</span> plasma with finite <span class="hlt">magnetic</span> field strength [Ng, Bhattacharjee, and Skiff, Phys. Plasmas 13, 055903 (2006)], with the additional effect of field-aligned current. Such solution might explain <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes observed to form within the diffusion region in 3D kinetic simulations of <span class="hlt">magnetic</span> reconnection, and the 2D version of them (plasmoids, secondary islands). We will present properties of solutions based on a range of typical plasma parameters within regions of the magnetosphere where <span class="hlt">magnetic</span> reconnection could happen. These solutions could potentially be used to compare with future Magnetospheric Multiscale Mission (MMS) observation. This work is supported by a National Science Foundation grant PHY-1004357 and the Alaska NASA EPSCoR Program (NNX13AB28A).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA127122','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA127122"><span>A Quantitative Study of <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Transport on the Sun,</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1983-02-15</p> <p>the Sun . Using Kitt Peak magnetograms as input, as have determined a best-fit diffusion constant by comparing the computed and observed fields at later times. This paper presents the initial results of a project to simulate the transport of solar <span class="hlt">magnetic</span> <span class="hlt">flux</span> using diffusion, differential rotation, and meridional flow. The study concerns the evolution of large-scale fields on a time scale of weeks of years, and ignores the rapid changes that accompany the emergence of new <span class="hlt">magnetic</span> regions and the day-to-day changes of the supergranular network</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990RMxAA..21..549B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990RMxAA..21..549B"><span><span class="hlt">Magnetic</span> Bipoles in Emerging <span class="hlt">Flux</span> Regions on the Sun</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barth, C. S.; Livi, S. H. B.</p> <p>1990-11-01</p> <p>ABSTRACT. We analyse magnetograms and H-alpha filtergrams of an Emerging <span class="hlt">Flux</span> Region. Small bipoles have been observed on the magnetograms emerging between opposite polarities. Separation velocities of the opposite poles for 45 bipoles observed on June 9, 1985 have been measured and are in the range 0.5 < Vs < 3.5 km/s. A significant <span class="hlt">magnetic</span> <span class="hlt">flux</span> increase in the region was observed due to contributions from the emerging bipoles. RESUMEN. Se analizan magnetogramas y filtrogramas en H-alfa de una region de flujo emergente. Se observan pequenos dipolos en los magnetogramas emergiendo entre polaridades opuestas. Se midieron velocidades de separacion de polos opuestos para 45 bipolos observados en junio 9 de 1985 y estan en el intervalo 0.5 < Vs < 3.5 km/s. Se observo un aumento significativo del flujo magnetico en la region debido a contribuciones de los bipolos emergentes. Key words: SUN-CHROMOSPHERE - SUN-<span class="hlt">MAGNETIC</span> FIELDS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSemi..37j2003F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSemi..37j2003F"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> assisted thermospin transport in a Rashba ring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, Liang; Benling, Gao; Yu, Gu</p> <p>2016-10-01</p> <p>The electron transport through a Rashba ring with a <span class="hlt">magnetic</span> <span class="hlt">flux</span> and driven by a temperature difference is investigated. It is found that the spin interference effect induced by the Rashba spin-orbit interaction and by the <span class="hlt">magnetic</span> <span class="hlt">flux</span> can break the balance between the spin-up and spin-down component currents in the thermally driven charge current and thus result in a spin current. The analytical derivation and numerical calculations reveal that the magnitude, sign, peaks and spin-polarization of the generated spin current can be readily modulated by the system parameters. In particular, with some choices of the parameters, the spin polarization of the generated spin current can reach 100%, that is, a fully spin-polarized thermospin current can be produced. These results may help the use of the spin-dependent Seebeck effect to generate and manipulate a spin current. Project supported by the National Natural Science Foundation of China (No.11404142).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010086596&hterms=508&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D508','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010086596&hterms=508&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D508"><span>Coronal Heating and the <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Content of the Network</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.; Whitaker, Ann F. (Technical Monitor)</p> <p>2001-01-01</p> <p>Previously, from analysis of SOHO/EIT coronal images in combination with Kitt Peak magnetograms (Falconer et al 1998, ApJ, 501, 386-396), we found that the quiet corona is the sum of two components: the e-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature (T approx. 10(exp 6) K) structures larger than supergranules (>approx.30,000 km). The coronal network (1) consists of all coronal-temperature structures smaller than supergranules, (2) is rooted in and loosely traces the photospheric <span class="hlt">magnetic</span> network, (3) has its brightest features seated on polarity dividing fines (neutral lines) in the network <span class="hlt">magnetic</span> <span class="hlt">flux</span>, and (4) produces only about 5% of the total coronal emission in quiet regions. The heating of the coronal network is apparently <span class="hlt">magnetic</span> in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying <span class="hlt">magnetic</span> network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> content of the underlying <span class="hlt">magnetic</span> network. In contrast, Fisher et A (1998, ApJ, 508, 985-998) found that the coronal radiation from an active region increases roughly linearly with the <span class="hlt">magnetic</span> <span class="hlt">flux</span> content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is <span class="hlt">magnetically</span> rooted in the network. Our results, together with the result of Fisher et al (1999), suggest that either the coronal heating in quiet regions has a large non-<span class="hlt">magnetic</span> component, or, if the heating</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUSM..SH31D06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM..SH31D06F"><span>Coronal Heating and the <span class="hlt">Magnetic</span> <span class="hlt">Flux</span> Content of the Network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Falconer, D. A.; Moore, R. L.; Porter, J. G.; Hathaway, D. H.</p> <p>2001-05-01</p> <p>Previously, from analysis of SOHO/EIT coronal images in combination with Kitt Peak magnetograms (Falconer et al 1998, ApJ, 501, 386-396), we found that the quiet corona is the sum of two components: the large-scale corona and the coronal network. The large-scale corona consists of all coronal-temperature ( million-degree) structures larger than the width of a chromospheric network lane (> 10,000 km). The coronal network (1) consists of all coronal-temperature structures of the scale of the network lanes and smaller (< 10,000 km), (2) is rooted in and loosely traces the photospheric <span class="hlt">magnetic</span> network, (3) has its brightest features seated on polarity dividing lines (neutral lines) in the network <span class="hlt">magnetic</span> <span class="hlt">flux</span>, and (4) produces only about 5% of the total coronal emission in quiet regions. The heating of the coronal network is apparently <span class="hlt">magnetic</span> in origin. Here, from analysis of EIT coronal images of quiet regions in combination with magnetograms of the same quiet regions from SOHO/MDI and from Kitt Peak, we examine the other 95% of the quiet corona and its relation to the underlying <span class="hlt">magnetic</span> network. We find: (1) Dividing the large-scale corona into its bright and dim halves divides the area into bright "continents" and dark "oceans" having spans of 2-4 supergranules. (2) These patterns are also present in the photospheric magnetograms: the network is stronger under the bright half and weaker under the dim half. (3) The radiation from the large-scale corona increases roughly as the cube root of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> content of the underlying <span class="hlt">magnetic</span> network. In contrast, Fisher et al (1998, ApJ, 508, 985-998) found that the coronal radiation from an active region increases roughly linearly with the <span class="hlt">magnetic</span> <span class="hlt">flux</span> content of the active region. We assume, as is widely held, that nearly all of the large-scale corona is <span class="hlt">magnetically</span> rooted in the network. Our results, together with the result of Fisher et al (1998), suggest that either the coronal heating in quiet regions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006ASTRA...2...63N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006ASTRA...2...63N"><span>Are heliospheric flows <span class="hlt">magnetic</span> line- or <span class="hlt">flux</span>-conserving?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nickeler, D. H.; Karlický, M.</p> <p>2006-11-01</p> <p>This article discusses and tests the validity of the frozen in <span class="hlt">magnetic</span> field paradigm (or 'ideal magnetohydrodynamics (MHD) constraint') which is usually adopted by many authors dealing with heliospheric physics. To show the problem of using ideal MHD in such a counterflow configuration like the heliosphere, we first recapitulate the basic concepts of freezing-in of <span class="hlt">magnetic</span> fields, respectively <span class="hlt">magnetic</span> topology conservation and its violation (= <span class="hlt">magnetic</span> reconnection) in 3-D, already done by other authors with different methods with respect to derivations and interpretations. Then we analyse different heliospheric plasma environments. As a model of the stagnation region/stagnation point in front of the heliospheric nose, we present and discuss the general solution of the ideal MHD Ohm's law in the vicinity of a 2-D stagnation point, which was found by us. We show that ideal MHD either leads necessarily to a diverging <span class="hlt">magnetic</span> field strength in the vicinity of such a stagnation point, or to a vanishing mass density on the heliopause boundaries. In the case that components of the electric field parallel to the <span class="hlt">magnetic</span> field do not exist due to the chosen form of the non-ideal Ohm's law, it is always possible to formulate the transport equation of the <span class="hlt">magnetic</span> field as a modified ideal Ohm's law. We find that the form of the Ohm's law which is often used in heliospheric physics (see e.g. Baranov and Fahr, 2003), is not able to change <span class="hlt">magnetic</span> topology and thus cannot lead to <span class="hlt">magnetic</span> reconnection, which necessarily has to occur at the stagnation point. The diverging <span class="hlt">magnetic</span> field, for instance, implies the breakdown of the <span class="hlt">flux</span> freezing paradigm for the heliosphere. Its application, especially at the heliospheric nose, is therefore rather doubtful. We conclude that it is necessary to search for an Ohm's law which is able to violate <span class="hlt">magnetic</span> topology conservation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15672369','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15672369"><span>Morphological anomalies in pollen <span class="hlt">tubes</span> of Actinidia deliciosa (kiwi) exposed to 50 Hz <span class="hlt">magnetic</span> field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dattilo, Arduino M; Bracchini, Luca; Loiselle, Steven A; Ovidi, Elisa; Tiezzi, Antonio; Rossi, Claudio</p> <p>2005-02-01</p> <p>The role of the pollen grain, with respect to the reproductive process of higher plants, is to deliver the spermatic cells to the embryo sac for egg fertilisation. Delivery occurs through the pollen <span class="hlt">tube</span>, a self produced organ that is generated when the pollen grain reaches the stigma surface. The effect of <span class="hlt">magnetic</span> fields on pollen <span class="hlt">tube</span> growth was reported in a recent publication by Germanà et al. Pollen <span class="hlt">tube</span> growth is an interesting candidate for the detailed study of the effects of electromagnetic fields on cytoplasmic structures and organelles. In this research Actinidia deliciosa (kiwifruit) pollen grains were germinated in the presence of an alternating <span class="hlt">magnetic</span> field (50 Hz). Our results, although of preliminary nature, show that pollen <span class="hlt">tube</span> growth is affected by <span class="hlt">magnetic</span> fields. The analysis of the observed anomalies in the pollen <span class="hlt">tube</span> appear to be the result of changes in the ionic charges within the pollen <span class="hlt">tube</span> cytoplasm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/260566','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/260566"><span>Alternative <span class="hlt">magnetic</span> <span class="hlt">flux</span> leakage modalities for pipeline inspection</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Katragadda, G.; Lord, W.; Sun, Y.S.; Udpa, S.; Udpa, L.</p> <p>1996-05-01</p> <p>Increasing quality consciousness is placing higher demands on the accuracy and reliability of inspection systems used in defect detection and characterization. Nondestructive testing techniques often rely on using multi-transducer approaches to obtain greater defect sensitivity. This paper investigates the possibility of taking advantage of alternative modalities associated with the standard <span class="hlt">magnetic</span> <span class="hlt">flux</span> leakage tool to obtain additional defect information, while still using a single excitation source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1042286','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1042286"><span><span class="hlt">Magnetic</span> and Electric <span class="hlt">Flux</span> Quanta: the Pion Mass</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>P Cameron</p> <p>2011-12-31</p> <p>The angular momentum of the <span class="hlt">magnetic</span> <span class="hlt">flux</span> quantum is balanced by that of the associated supercurrent, such that in condensed matter the resultant angular momentum is zero. The notion of a <span class="hlt">flux</span> quantum in free space is not so simple, needing both <span class="hlt">magnetic</span> and electric <span class="hlt">flux</span> quanta to propagate the stable dynamic structure of the photon. Considering these <span class="hlt">flux</span> quanta at the scale where quantum field theory becomes essential, at the scale defined by the reduced Compton wavelength of the electron, exposes variants of a paradox that apparently has not been addressed in the literature. Leaving the paradox unresolved in this note, reasonable electromagnetic rationales are presented that permit to calculate the masses of the electron, muon, pion, and nucleon with remarkable accuracy. The calculated mass of the electron is correct at the nine significant digit limit of experimental accuracy, the muon at a part in one thousand, the pion at two parts in ten thousand, and the nucleon at seven parts in one hundred thousand. The accuracy of the pion and nucleon mass calculations reinforces the unconventional common notion that the strong force is electromagnetic in origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10963463','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10963463"><span>Placement of nasoenteral feeding <span class="hlt">tubes</span> using <span class="hlt">magnetic</span> guidance: retesting a new technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ozdemir, B; Frost, M; Hayes, J; Sullivan, D H</p> <p>2000-08-01</p> <p>To study a new technique of intubating the small bowel using a newly developed nasoenteral feeding <span class="hlt">tube</span> fitted with a <span class="hlt">magnet</span> in its tip and guided for placement with an external <span class="hlt">magnet</span>. The study was performed in medical and surgical wards of a university-affiliated Department of Veterans Affairs hospital on 42 patients referred by their attending physicians for <span class="hlt">tube</span> placement. The newly designed feeding <span class="hlt">tube</span> was inserted per nares into the stomach using traditional technique. As the <span class="hlt">tube</span> was advanced, movement of the hand-held steering <span class="hlt">magnet</span> was designed to guide the tip of the <span class="hlt">magnetic</span> nasoenteral <span class="hlt">tube</span> along the lesser curvature of the stomach, through the pyloric sphincter, and into the duodenum. Portable abdominal radiography confirmed the anatomic location of the <span class="hlt">tube</span> tip. Fifty-one intubations were performed on 42 subjects. In 45 intubations (88%), <span class="hlt">tubes</span> passed into the duodenum. Twenty-seven (53%) met criteria for optimal placement in the second portion of the duodenum or distally. Six of 11 <span class="hlt">tubes</span> (55%) that were not optimally placed were advanced to the distal duodenum on repositioning. Median procedure time for the initial intubations was 30 minutes (interquartile range 15-40). Median procedure time for last 10 intubations improved to 13 minutes (interquartile range 5-20). No complications were related to the procedure. Enteral feeding <span class="hlt">tube</span> placement using external <span class="hlt">magnetic</span> guidance is a promising, novel technique which is deserving of further study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPNM9004G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPNM9004G"><span>Stability of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes with background flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goedbloed, Hans; Keppens, Rony</p> <p>2012-10-01</p> <p>MHD stability of <span class="hlt">magnetic</span> <span class="hlt">flux</span> ropes is usually studied from the view point of perturbing a static equilibrium background, whereas the significant background flow that is usually present completely modifies the stability of such systems. A new theory, based on energy conservation and self-adjoint operators, permits the computation of the full spectrum of waves and instabilities of stationary plasmas. It involves the construction of a network of curves (the spectral web) in the complex omega-plane associated with the complex complementary energy, which is the energy needed to maintain harmonic time dependence in an open system. Vanishing of that energy, at the intersections of the mentioned curves, yields the eigenvalues of the closed system. Thus, for the first time, knowledge of the full complex spectrum of modes together with a connecting structure is obtained. This theory is applied to compute the complete spectrum of waves and instabilities of <span class="hlt">flux</span> ropes in a thin accretion disk and of the rotating <span class="hlt">magnetized</span> jets emitted from those disks. It yields specific stability criteria in terms of the helicities of the <span class="hlt">magnetic</span> field and of the flow velocity that may be compared with observable parameters of the <span class="hlt">flux</span> ropes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/813604','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/813604"><span><span class="hlt">Flux</span> Rope Acceleration and Enhanced <span class="hlt">Magnetic</span> Reconnection Rate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>C.Z. Cheng; Y. Ren; G.S. Choe; Y.-J. Moon</p> <p>2003-03-25</p> <p>A physical mechanism of flares, in particular for the flare rise phase, has emerged from our 2-1/2-dimensional resistive MHD simulations. The dynamical evolution of current-sheet formation and <span class="hlt">magnetic</span> reconnection and <span class="hlt">flux</span>-rope acceleration subject to continuous, slow increase of <span class="hlt">magnetic</span> shear in the arcade are studied by employing a non-uniform anomalous resistivity in the reconnecting current sheet under gravity. The simulation results directly relate the <span class="hlt">flux</span> rope's accelerated rising motion with an enhanced <span class="hlt">magnetic</span> reconnection rate and thus an enhanced reconnection electric field in the current sheet during the flare rise phase. The simulation results provide good quantitative agreements with observations of the acceleration of <span class="hlt">flux</span> rope, which manifests in the form of SXR ejecta or erupting filament or CMEs, in the low corona. Moreover, for the X-class flare events studied in this paper the peak reconnection electric field is about O(10{sup 2} V/m) or larger, enough to accelerate p articles to over 100 keV in a field-aligned distance of 10 km. Nonthermal electrons thus generated can produce hard X-rays, consistent with impulsive HXR emission observed during the flare rise phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21612590','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21612590"><span>Confinement and Lattice Quantum-Electrodynamic Electric <span class="hlt">Flux</span> <span class="hlt">Tubes</span> Simulated with Ultracold Atoms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zohar, Erez; Reznik, Benni</p> <p>2011-12-30</p> <p>We propose a method for simulating (2+1)D compact lattice quantum-electrodynamics, using ultracold atoms in optical lattices. In our model local Bose-Einstein condensates' (BECs) phases correspond to the electromagnetic vector potential, and the local number operators represent the conjugate electric field. The well-known gauge-invariant Kogut-Susskind Hamiltonian is obtained as an effective low-energy theory. The field is then coupled to external static charges. We show that in the strong coupling limit this gives rise to ''electric <span class="hlt">flux</span> <span class="hlt">tubes</span>'' and to confinement. This can be observed by measuring the local density deviations of the BECs, and is expected to hold even, to some extent, outside the perturbative calculable regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/878071','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/878071"><span>Limited Streamer <span class="hlt">Tubes</span> for the BaBar Instrumented <span class="hlt">Flux</span> Return Upgrade</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lu, C.; /Princeton U.</p> <p>2005-10-11</p> <p>Starting from the very beginning of their operation the efficiency of the RPC chambers in the BaBar Instrumented <span class="hlt">Flux</span> Return (IFR) has suffered serious degradation. After intensive investigation, various remediation efforts had been carried out, but without success. As a result the BaBar collaboration decided to replace the dying barrel RPC chambers about two years ago. To study the feasibility of using the Limited Streamer <span class="hlt">Tube</span> (LST) as the replacement of RPC we carried out an R&D program that has resulted in BaBar's deciding to replace the barrel RPC's with LST's. In this report we summarize the major detector R&D results, and leave other issues of the IFR system upgrade to the future publications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhRvD..86a4008D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhRvD..86a4008D"><span>X(1835), X(2120), and X(2370) in <span class="hlt">flux</span> <span class="hlt">tube</span> models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deng, Chengrong; Ping, Jialun; Yang, Youchang; Wang, Fan</p> <p>2012-07-01</p> <p>Nonstrange hexaquark state q3q¯3 spectrum is systematically studied by using the Gaussian expansion method in <span class="hlt">flux</span> <span class="hlt">tube</span> models with a six-body confinement potential. All the model parameters are fixed by baryon properties, so the calculation of hexaquark state q3q¯3 is parameter-free. It is found that some ground states of q3q¯3 are stable against disintegrating into a baryon and an anti-baryon. The main components of X(1835) and X(2370), which are observed in the radiative decay of J/ψ by BES collaboration, can be described as compact hexaquark states N8N¯8 and Δ8Δ¯8 with quantum numbers IGJPC=0+0-+, respectively. These bound states should be color confinement resonances with three-dimensional configurations similar to a rugby ball, however, X(2120) can not be accommodated in this model approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SoPh..290.1889H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SoPh..290.1889H"><span>Multiple Scattering of Seismic Waves from Ensembles of Upwardly Lossy Thin <span class="hlt">Flux</span> <span class="hlt">Tubes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hanson, Chris S.; Cally, Paul S.</p> <p>2015-07-01</p> <p>Our previous semi-analytic treatment of - and -mode multiple scattering from ensembles of thin <span class="hlt">flux</span> <span class="hlt">tubes</span> (Hanson and Cally, Astrophys. J. 781, 125, 2014a; 791, 129, 2014b) is extended by allowing both sausage and kink waves to freely escape at the top of the model using a radiative boundary condition there. As expected, this additional avenue of escape, supplementing downward loss into the deep solar interior, results in substantially greater absorption of incident - and -modes. However, less intuitively, it also yields mildly to substantially smaller phase shifts in waves emerging from the ensemble. This may have implications for the interpretation of seismic data for solar plage regions, and in particular their small measured phase shifts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6019414','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6019414"><span>Refilling of geosynchronous <span class="hlt">flux</span> <span class="hlt">tubes</span> as observed at the equator by GEOS 2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sojka, J.J.; Wrenn, G.L.</p> <p>1985-07-01</p> <p>During periods of extended quiet geomagnetic activity the geosynchronous satellite orbit lies inside the plasmasphere. Five such periods were observed by the GEOS 2 satellite. During the initial 48 hours of such periods the equatorial plasma <span class="hlt">flux</span> <span class="hlt">tube</span> density increases at 30 to 50 per cu cm/day. However, on reaching approximately 100 per cu cm the refilling rate decreases, and refilling is limited. Only when the density reaches approximately 100 per cu cm do the plasma characteristics and fluctuations appear to be plasmaspheric and the flow predominantly corotational. The hot outer zone of the plasmasphere is highly structured in density and temperature when viewed from a corotating satellite. This region also has a relatively dense population of warm subkilovolt electrons. These warm electrons whose density is approximately 1 percent to 50 percent of the cold plasma may be the heat source for the hot outer zone ions. 36 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Cryo...32.1076P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Cryo...32.1076P"><span><span class="hlt">Magnetic</span> <span class="hlt">flux</span> distribution and <span class="hlt">magnetic</span> relaxation in polycrystalline Bi,PbSrCaCuO superconductors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (A