Science.gov

Sample records for magnetic multipole plasma

  1. Magnetic multipole redirector of moving plasmas

    DOEpatents

    Crow, James T.; Mowrer, Gary R.

    1999-01-01

    A method and apparatus for redirecting moving plasma streams using a multiple array of magnetic field generators (e.g., permanent magnets or current bearing wires). Alternate rows of the array have opposite magnetic field directions. A fine wire mesh may be employed to focus as well as redirect the plasma.

  2. Superconducting multipole corrector magnet

    SciTech Connect

    Kashikhin, Vladimir; /Fermilab

    2004-10-01

    A novel concept of superconducting multipole corrector magnet is discussed. This magnet assembled from 12 identical racetrack type coils and can generate any combination of dipole, quadrupole and sextupole magnetic fields. The coil groups are powered from separate power supplies. In the case of normal dipole, quadrupole and sextupole fields the total field is symmetrical relatively the magnet median plane and there are only five powered separately coil groups. This type multipole corrector magnet was proposed for BTeV, Fermilab project and has following advantages: universal configuration, simple manufacturing and high mechanical stability. The results of magnetic design including the field quality and magnetic forces in comparison with known shell type superconducting correctors are presented.

  3. Magnetic Multipoles in Theory and Practice.

    ERIC Educational Resources Information Center

    Smith, D. G.

    1980-01-01

    A magnetic multipole apparatus suitable for the physics teaching laboratory is described. The apparatus enables the student to measure the magnetic field configuration of a single large coil, and of systems of one or more small coils. (Author/DS)

  4. Permanent multipole magnets with adjustable strength

    SciTech Connect

    Halbach, K.

    1983-03-01

    Preceded by a short discussion of the motives for using permanent magnets in accelerators, a new type of permanent magnet for use in accelerators is presented. The basic design and most important properties of a quadrupole will be described that uses both steel and permanent magnet material. The field gradient produced by this magnet can be adjusted without changing any other aspect of the field produced by this quadrupole. The generalization of this concept to produce other multipole fields, or combination of multipole fields, will also be presented.

  5. Multipole Analysis of Circular Cylindircal Magnetic Systems

    SciTech Connect

    Selvaggi, Jerry P.

    2005-12-01

    This thesis deals with an alternate method for computing the external magnetic field from a circular cylindrical magnetic source. The primary objective is to characterize the magnetic source in terms of its equivalent multipole distribution. This multipole distribution must be valid at points close to the cylindrical source and a spherical multipole expansion is ill-equipped to handle this problem; therefore a new method must be introduced. This method, based upon the free-space Green's function in cylindrical coordinates, is developed as an alternative to the more familiar spherical harmonic expansion. A family of special functions, called the toroidal functions or Q-functions, are found to exhibit the necessary properties for analyzing circular cylindrical geometries. In particular, the toroidal function of zeroth order, which comes from the integral formulation of the free-space Green's function in cylindrical coordinates, is employed to handle magnetic sources which exhibit circular cylindrical symmetry. The toroidal functions, also called Q-functions, are the weighting coefficients in a ''Fourier series-like'' expansion which represents the free-space Green's function. It is also called a toroidal expansion. This expansion can be directly employed in electrostatic, magnetostatic, and electrodynamic problems which exhibit cylindrical symmetry. Also, it is shown that they can be used as an alternative to the Elliptic integral formulation. In fact, anywhere that an Elliptic integral appears, one can replace it with its corresponding Q-function representation. A number of problems, using the toroidal expansion formulation, are analyzed and compared to existing known methods in order to validate the results. Also, the equivalent multipole distribution is found for most of the solved problems along with its corresponding physical interpretation. The main application is to characterize the external magnetic field due to a six-pole permanent magnet motor in terms of

  6. Higher order multipole magnet tolerances

    SciTech Connect

    Chao, A.W.; Lee, M.J.; Morton, P.M.

    1988-01-01

    Due to field impurities in the magnets in a storage ring or circular accelerator the values of the betatron frequencies for a given particle in a beam are dependent upon the energy and betatron amplitude of the particle as well as the values of the energy dispersion and betatron functions at the magnets. A method has been developed for finding the values of the betatron frequencies for any particle with given field impurities. This method has been used to study the quality of several preliminary designs of some of the quadrupole magnets in PEP by comparing the variations of the betatron frequencies over the maximum expected range of values of the particle energy and betatron amplitude. The expressions for the values of betatron frequencies as functions of the various beam and machine parameters are derived. Some of the results for the evaluation of two types of the PEP magnets are also presented. A discussion of these results is given as well. 3 refs., 5 figs., 2 tabs.

  7. Computational Study of Plasma Response to a Variable Electric Multipole Configuration

    NASA Astrophysics Data System (ADS)

    Hicks, Nathaniel

    2016-10-01

    A computational study is presented of the behavior of a low temperature, quasi-neutral plasma in a three-dimensional, time-varying electric multipole field. A 3-D particle- in-cell (PIC) plasma code is used to simulate the process. The simulations study the effect of the plasma species' mass difference on the plasma response, with the multipole field frequency being chosen, for example, to interact strongly with light particles but negligibly with heavy ones. The effect of focusing the light species to the center of the multipole structure is examined, with space charge neutralized by the presence of the heavy species. The dependence of plasma density on driving field parameters and geometry (order of multipole, shape of equipotential surfaces) is studied, as well as the behavior of the plasma near gyroresonance in the presence of a background magnetic field. The formation and dependences of the RF plasma sheath are studied, as the sheath responds to variation of the plasma and external field characteristics. The results of the computer modeling study are to inform an initial experimental design and study of the same effects. Supported by NSF/DOE Partnership in Basic Plasma Physics and Engineering Award PHY-1619615.

  8. Permanent magnet multipole with adjustable strength

    DOEpatents

    Halbach, Klaus

    1985-01-01

    Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling therebetween. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

  9. Permanent-magnet multipole with adjustable strength

    DOEpatents

    Halbach, K.

    1982-09-20

    Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling there between. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

  10. Experience with the SLC permanent magnet multipoles

    SciTech Connect

    Gross, G.; Spencer, J.

    1994-06-01

    Permanent magnets have been used in the SLC Damping Rings and their injection and extraction lines since 1985. Recent upgrades of the DR vacuum chambers provided an opportunity to check DR magnets prior to higher beam current operation. Several PM sextupoles downstream of the injection kickers in the electron ring had exceeded their thermal stabilization values of 80{degrees}C and some showed serious mechanical deformations and radiation >1 R at contact. We discuss our observations, measurements and a few inexpensive modifications that should improve these magnets under such conditions. A new, block matching algorithm allowed us to use magnet blocks that had been considered unusable because of very different remament field strengths and easy axis errors.

  11. Multipole shimming of permanent magnets using harmonic corrector rings.

    PubMed

    Jachmann, R C; Trease, D R; Bouchard, L-S; Sakellariou, D; Martin, R W; Schlueter, R D; Budinger, T F; Pines, A

    2007-03-01

    Shimming systems are required to provide sufficient field homogeneity for high resolution nuclear magnetic resonance (NMR). In certain specialized applications, such as rotating-field NMR and mobile ex situ NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.

  12. Analytical expressions for fringe fields in multipole magnets

    NASA Astrophysics Data System (ADS)

    Muratori, B. D.; Jones, J. K.; Wolski, A.

    2015-06-01

    Fringe fields in multipole magnets can have a variety of effects on the linear and nonlinear dynamics of particles moving along an accelerator beam line. An accurate model of an accelerator must include realistic models of the magnet fringe fields. Fringe fields for dipoles are well understood and can be modeled at an early stage of accelerator design in such codes as mad8, madx, gpt or elegant. Existing techniques for quadrupole and higher order multipoles rely either on the use of a numerical field map, or on a description of the field in the form of a series expansion about a chosen axis. Usually, it is not until the later stages of a design project that such descriptions (based on magnet modeling or measurement) become available. Furthermore, series expansions rely on the assumption that the beam travels more or less on axis throughout the beam line; but in some types of machines (for example, Fixed Field Alternating Gradients or FFAGs) this is not a good assumption. Furthermore, some tracking codes, such as gpt, use methods for including space charge effects that require fields to vary smoothly and continuously along a beam line: in such cases, realistic fringe field models are of significant importance. In this paper, a method for constructing analytical expressions for multipole fringe fields is presented. Such expressions allow fringe field effects to be included in beam dynamics simulations from the start of an accelerator design project, even before detailed magnet design work has been undertaken. The magnetostatic Maxwell equations are solved analytically and a solution that fits all orders of multipoles is derived. Quadrupole fringe fields are considered in detail as these are the ones that give the strongest effects. The analytic expressions for quadrupole fringe fields are compared with data obtained from numerical modeling codes in two cases: a magnet in the high luminosity upgrade of the Large Hadron Collider inner triplet, and a magnet in the

  13. Neptune radio emission in dipole and multipole magnetic fields

    NASA Technical Reports Server (NTRS)

    Sawyer, C. B.; King, N. V.; Romig, J. H.; Warwick, J. W.

    1995-01-01

    We study Neptune's smooth radio emission in two ways: we simulate the observations and we then consider the radio effects of Neptune's magnetic multipoles. A procedure to deduce the characteristics of radio sources observed by the Planetary Radio Astronomy experiment minimizes limiting assumptions and maximizes use of the data, including quantitative measurement of circular polarization. Study of specific sources simulates time variation of intensity and apparent polarization of their integrated emission over an extended time period. The method is applied to Neptune smooth recurrent emission (SRE). Time series are modeled with both broad and beamed emission patterns, and at two frequencies which exhibit different time variation of polarization. These dipole-based results are overturned by consideration of more complex models of Neptune's magnetic field. Any smooth emission from the anticipated auroral radio source is weak and briefly observed. Dominant SRE originates complex fields at midlatitude. Possible SRE source locations overlap that of 'high-latitude' emission (HLE) between +(out) and -(in) quadrupoles. This is the first identification of multipolar magnetic structure with a major source of planetary radio emission.

  14. Global Aspects of Charged Particle Motion in Axially Symmetric Multipole Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    2003-01-01

    The motion of a single charged particle in the space outside of a compact region of steady currents is investigated. The charged particle is assumed to produce negligible electromagnetic radiation, so that its energy is conserved. The source of the magnetic field is represented as a point multipole. After a general description, attention is focused on magnetic fields with axial symmetry. Lagrangian dynamical theory is utilized to identify constants of the motion as well as the equations of motion themselves. The qualitative method of Stonner is used to examine charged particle motion in axisymmetric multipole fields of all orders. Although the equations of motion generally have no analytical solutions and must be integrated numerically to produce a specific orbit, a topological examination of dynamics is possible, and can be used, d la Stonner, to completely describe the global aspects of the motion of a single charged particle in a space with an axisymmetric multipole magnetic field.

  15. Improved measurement surface for MEG using magnetic-dipole sources and a spherical-multipole expansion

    NASA Astrophysics Data System (ADS)

    Argin, F.; Ahrens, H.; Klinkenbusch, L.

    2012-09-01

    The multipole representation of Magnetoencephalography (MEG) signals is known as a useful tool for distinguishing between magnetic fields arising from the brain and external disturbances. In this contribution we extend this concept and show that a closed double-layer surface with magnetometer probes is better suited to determine the corresponding multipole amplitudes αlm than a conventional single-layer surface with gradiometers and magnetometer probes. For two different source configurations we show that the αlm rapidly converge to the exact values. This proof of concept motivates to further optimize the geometry of the double-layer surface and the sensors' positions.

  16. Influence of Magnet Multipole Field Components on Beam Dynamics in the JLEIC Ion Collider Ring

    SciTech Connect

    Wei, Guohui; Morozov, Vasiliy; Lin, Fanglei; Zhang, Yuhong; Pilat, Fulvia C.; Wang, Min-Huey

    2016-05-01

    To get a luminosity level of a few 1033 cm-2ses₋1 at all design points of the Jefferson Lab Electron Ion Collider (JLEIC) project, small β* values in both horizontal and vertical planes are necessary at the Interaction Point (IP) in the ion collider ring. This also means large β in the final focus area, chromaticity correction sections, etc. which sets a constraint on the field quality of magnets in large beta areas, in order to ensure a large enough dynamic aperture (DA). In this context, limiting multipole field components of magnets are surveyed to find a possible compromise between the requirements and what can be realistically achieved by a magnet manufacturer. This paper describes that work. Moreover, non-linear field dedicated correctors are also studied to provide semi-local corrections of specific multipole field components.

  17. Cyclic Variations of Near-Earth Conditions and Solar Magnetic Multipole Fields

    NASA Astrophysics Data System (ADS)

    Kim, B.; Lee, J.; Oh, S.; Yi, Y.

    2014-12-01

    We have investigated the cyclic variations of the magnetic multipole components of solar fields in comparison with various indices for the solar, interplanetary, and geomagnetic activities measured from 1976 to 2012 (from Solar Cycle 21 to the early phase of Cycle 24). The magnetic multipole components are calculated using the synoptic magnetic field data and the potential field source surface (PFSS) model of the Wilcox Solar Observatory (WSO). While most solar activity indices such as sunspot number, total solar irradiance, 10.7 cm radio flux, and solar flare occurrence rate are highly correlated with the flux of magnetic quadrupole component, the solar wind dynamic pressure and the geomagnetic activity index, AE, are rather correlated with the dipole and higher-order pole components, respectively. The cyclic variation of the dipole components is out of phase with the solar sunspot cycle and that of the quadrupole component is in phase. It is therefore argued that the temporal correlations of the activity indices with the individual multipole components as found in this study may clarify why some of the activity indices are seemingly out of phase with the sunspot cycle.

  18. Combining multipole data

    SciTech Connect

    Michelotti, L.

    1987-03-01

    The problem of combining the information from three sets of magnetic field data for dipole magnets is addressed. Three methods for combining multipole data are described which may be useful under possibly different assumptions: multipole feeddown, expansion in orthogonal functions, and fictitious sources. The methods of multipole feeddown and sources were both tried on the magnet data, with the result that the method of sources worked well. (LEW)

  19. Oxidation of gallium arsenide in a plasma multipole device. Study of the MOS structures obtained

    NASA Technical Reports Server (NTRS)

    Gourrier, S.; Mircea, A.; Simondet, F.

    1980-01-01

    The oxygen plasma oxidation of GaAs was studied in order to obtain extremely high frequency responses with MOS devices. In the multipole system a homogeneous oxygen plasma of high density can easily be obtained in a large volume. This system is thus convenient for the study of plasma oxidation of GaAs. The electrical properties of the MOS diodes obtained in this way are controlled by interface states, located mostly in the upper half of the band gap where densities in the 10 to the 13th power/(sq cm) (eV) range can be estimated. Despite these interface states the possibility of fabricating MOSFET transistors working mostly in the depletion mode for a higher frequency cut-off still exists.

  20. Bashful ballerina unveiled: Multipole analysis of the coronal magnetic field

    NASA Astrophysics Data System (ADS)

    Virtanen, I.; Mursula, K.

    2012-12-01

    Heliospheric current sheet (HCS) is the continuum of the coronal magnetic equator, dividing the heliospheric magnetic field (HMF) into two sectors (polarities). Because of its wavy structure, the HCS is often called the ballerina skirt. Several studies have proven that the HCS is southward shifted during about three years in the solar declining phase. This persistent phenomenon, called the bashful ballerina, has been verified by geomagnetic indices since 1930s, by OMNI data base since 1960s, by the WSO PFSS model since mid-1970s and by the Ulysses probe measurements during the fast latitude scans in 1994-1995 and 2007. We study here the Wilcox Solar Observatory measurements of the photospheric magnetic field and the PFSS extrapolation of the coronal magnetic field. We show that the quadrupole moment of the photospheric magnetic field, which is important for the HCS asymmetry (bashful ballerina), mainly arises from the difference between northern and southern polar field strengths. According to the WSO data the minimum time quadrupole is mainly due to the difference between the highest northern and southern latitude bins. Related studies imply that the southward shift of the HCS is related to the delayed development of southern coronal holes. We also discuss the suggested connection of the HCS asymmetry to sunspot hemispheric asymmetry.

  1. Orientation Measurement Based on Magnetic Inductance by the Extended Distributed Multi-Pole Model

    PubMed Central

    Wu, Fang; Moon, Seung Ki; Son, Hungsun

    2014-01-01

    This paper presents a novel method to calculate magnetic inductance with a fast-computing magnetic field model referred to as the extended distributed multi-pole (eDMP) model. The concept of mutual inductance has been widely applied for position/orientation tracking systems and applications, yet it is still challenging due to the high demands in robust modeling and efficient computation in real-time applications. Recently, numerical methods have been utilized in design and analysis of magnetic fields, but this often requires heavy computation and its accuracy relies on geometric modeling and meshing that limit its usage. On the other hand, an analytical method provides simple and fast-computing solutions but is also flawed due to its difficulties in handling realistic and complex geometries such as complicated designs and boundary conditions, etc. In this paper, the extended distributed multi-pole model (eDMP) is developed to characterize a time-varying magnetic field based on an existing DMP model analyzing static magnetic fields. The method has been further exploited to compute the mutual inductance between coils at arbitrary locations and orientations. Simulation and experimental results of various configurations of the coils are presented. Comparison with the previously published data shows not only good performance in accuracy, but also effectiveness in computation. PMID:24977389

  2. Some Considerations on Simple Non-Linear Magnetic Analysis-Based Optimum Design of Multi-Pole Permanent Magnet Machines

    NASA Astrophysics Data System (ADS)

    Kano, Yoshiaki; Kosaka, Takashi; Matsui, Nobuyuki

    This paper presents a simple non-linear magnetic analysis-based optimum design of a multi-pole permanent magnet machine as an assistant design tool of 3D-FEM. The proposed analysis is based on the equivalent magnetic circuit and the air gap permeance model between the stator and rotor teeth of the motor, taking into account the local magnetic saturation in the pointed end of teeth. The availability of the proposed analysis is verified by comparing with 3D-FEM analysis from the standpoints of the torque calculation accuracy for the variations of design free parameter and the computation time. After verification, the proposed analysis-based optimum design of the dimensions of permanent magnet is examined, by which the minimization of magnet volume is realized while keeping torque/current ratio at the specified value.

  3. Ultracold neutron accumulation in a superfluid-helium converter with magnetic multipole reflector

    NASA Astrophysics Data System (ADS)

    Zimmer, O.; Golub, R.

    2015-07-01

    We analyze the accumulation of ultracold neutrons (UCNs) in a superfluid-helium converter vessel surrounded by a magnetic multipole reflector. We solved the spin-dependent rate equation, employing formulas valid for adiabatic spin transport of trapped UCNs in mechanical equilibrium. Results for saturation UCN densities are obtained in dependence of order and strength of the multipolar field. The addition of magnetic storage to neutron optical potentials can increase the density and energy of the low-field-seeking UCNs produced and serves to mitigate the effects of wall losses on the source performance. It also can provide a highly polarized sample of UCNs without need to polarize the neutron beam incident on the converter. This work was performed in preparation of the UCN source project SuperSUN at the Institut Laue-Langevin.

  4. Poloidal OHMIC heating in a multipole

    SciTech Connect

    Holly, D.J.

    1982-01-01

    The feasibility of using poloidal currents to heat plasmas confined by a multipole field has been examined experimentaly in Tokapole II. The machine is operated as a toroidal octupole, with a time-varying toroidal magnetic field driving poloidal plasma currents I/sub plasma/ - 20 kA to give densities n/sub e/ - 10/sup 13/ cm/sup -3/ and temperatures T/sub e/ - 30 eV.

  5. Study on Optimum Design of Multi-Pole Interior Permanent Magnet Motor with Concentrated Windings

    NASA Astrophysics Data System (ADS)

    Kano, Yoshiaki; Kosaka, Takashi; Matsui, Nobuyuki

    Interior Permanent Magnet Synchronous Motors (IPMSM) have been found in many applications because of their high-power density and high-efficiency. The existence of a complex magnetic circuit, however, makes the design of this machine quite complicated. Although FEM is commonly used in the IPMSM design, one of disadvantages is long CPU times. This paper presents a simple non-linear magnetic analysis for a multi-pole IPMSM as a preliminary design tool of FEM. The proposed analysis consists of the geometric-flux-tube-based equivalent-magnetic-circuit model. The model includes saturable permeances taking into account the local magnetic saturation in the core. As a result, the proposed analysis is capable of calculating the flux distribution and the torque characteristics in the presence of magnetic saturation. The effectiveness of the proposed analysis is verified by comparing with FEM in terms of the analytical accuracy and the computation time for two IPMSMs with different specifications. After verification, the proposed analysis-based optimum design is examined, by which the minimization of motor volume is realized while satisfying the necessary maximum torque for target applications.

  6. Active Plasma Resonance Spectroscopy: Evaluation of a fluiddynamic-model of the planar multipole resonance probe using functional analytic methods

    NASA Astrophysics Data System (ADS)

    Friedrichs, Michael; Brinkmann, Ralf Peter; Oberrath, Jens

    2016-09-01

    Measuring plasma parameters, e.g. electron density and electron temperature, is an important procedure to verify the stability and behavior of a plasma process. For this purpose the multipole resonance probe (MRP) represents a satisfying solution to measure the electron density. However the influence of the probe on the plasma through its physical presence makes it unattractive for some processes in industrial application. A solution to combine the benefits of the spherical MRP with the ability to integrate the probe into the plasma reactor is introduced by the planar model of the MRP. By coupling the model of the cold plasma with the maxwell equations for electrostatics an analytical model for the admittance of the plasma is derivated, adjusted to cylindrical geometry and solved analytically for the planar MRP using functional analytic methods.

  7. Low loss pole configuration for multi-pole homopolar magnetic bearings

    NASA Technical Reports Server (NTRS)

    Blumenstock, Kenneth A. (Inventor); Hakun, Claef F. (Inventor)

    2001-01-01

    A new pole configuration for multi-pole homopolar bearings proposed in this invention reduces rotational losses caused by eddy-currents generated when non-uniform flux distributions exist along the rotor surfaces. The new homopolar magnetic bearing includes a stator with reduced pole-to-pole and exhibits a much more uniform rotor flux than with large pole-to-pole gaps. A pole feature called a pole-link is incorporated into the low-loss poles to provide a uniform pole-to-pole gap and a controlled path for pole-to-pole flux. In order to implement the low-loss pole configuration of magnetic bearings with small pole-to-pole gaps, a new stator configuration was developed to facilitate installation of coil windings. The stator was divided into sector shaped pieces, as many pieces as there are poles. Each sector-shaped pole-piece can be wound on a standard coil winding machine, and it is practical to wind precision layer wound coils. To achieve maximum actuation efficiency, it is desirable to use all the available space for the coil formed by the natural geometric configuration. Then, the coils can be wound in a tapered shape. After winding, the sectored-pole-pieces are installed into and fastened by bonding or other means, to a ring of material which encloses the sectored-pole-pieces, forming a complete stator.

  8. Variations of solar, interplanetary, and geomagnetic parameters with solar magnetic multipole fields during Solar Cycles 21-24

    NASA Astrophysics Data System (ADS)

    Kim, Bogyeong; Lee, Jeongwoo; Yi, Yu; Oh, Suyeon

    2015-01-01

    In this study we compare the temporal variations of the solar, interplanetary, and geomagnetic (SIG) parameters with that of open solar magnetic flux from 1976 to 2012 (from Solar Cycle 21 to the early phase of Cycle 24) for a purpose of identifying their possible relationships. By the open flux, we mean the average magnetic field over the source surface (2.5 solar radii) times the source area as defined by the potential field source surface (PFSS) model of the Wilcox Solar Observatory (WSO). In our result, most SIG parameters except the solar wind dynamic pressure show rather poor correlations with the open solar magnetic field. Good correlations are recovered when the contributions from individual multipole components are counted separately. As expected, solar activity indices such as sunspot number, total solar irradiance, 10.7 cm radio flux, and solar flare occurrence are highly correlated with the flux of magnetic quadrupole component. The dynamic pressure of solar wind is strongly correlated with the dipole flux, which is in anti-phase with Solar Cycle (SC). The geomagnetic activity represented by the Ap index is correlated with higher order multipole components, which show relatively a slow time variation with SC. We also found that the unusually low geomagnetic activity during SC 23 is accompanied by the weak open solar fields compared with those in other SCs. It is argued that such dependences of the SIG parameters on the individual multipole components of the open solar magnetic flux may clarify why some SIG parameters vary in phase with SC and others show seemingly delayed responses to SC variation.

  9. Plasma acceleration above martian magnetic anomalies.

    PubMed

    Lundin, R; Winningham, D; Barabash, S; Frahm, R; Holmström, M; Sauvaud, J-A; Fedorov, A; Asamura, K; Coates, A J; Soobiah, Y; Hsieh, K C; Grande, M; Koskinen, H; Kallio, E; Kozyra, J; Woch, J; Fraenz, M; Brain, D; Luhmann, J; McKenna-Lawler, S; Orsini, R S; Brandt, P; Wurz, P

    2006-02-17

    Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space.

  10. A Field Cancellation Algorithm for Constructing Economical Planar Permanent Magnet (PM) Multipoles With Large High Quality Field Apertures

    SciTech Connect

    Tatchyn, Roman; /SLAC

    2011-08-12

    In recent years studies have been initiated on a new class of multipole field generators consisting of cuboid planar permanent magnet (PM) pieces arranged in biplanar arrays of 2-fold rotational symmetry. These structures, first introduced for Free Electron Laser (FEL) applications, are based on reducing the rotational symmetry of conventional N-pole field generators from N-fold to 2-fold. One consequence of this reduction is a large higher-multipole content in a planar PM multipole's field at distances relatively close to the structure's axis, making it generally unsuitable for applications requiring a large high-quality field aperture. In this paper we outline an economical field-cancellation algorithm that can substantially decrease the harmonic content of a planar PM's field without breaking its biplanar geometry or 2-fold rotational symmetry. An economical field-cancellation algorithm has been described which will allow the fabrication of bi-planar quadrupoles and sextupoles with high-quality fields using a manageably small number of PM pieces. For higher order N-poles the number of pieces required to cancel a given number of successively-higher multipole components will also increase linearly; nevertheless, the practicability of fabricating octupoles and higher N-poles of this type should be considered a subject of continuing r&d. Since the removal of a large number of successive multipole components essentially increases the transverse region over which the N-pole's field is dominated by its leading N-pole field component, the fabrication of quadrupoles and sextupoles of the type described in this paper should lead to their introduction in storage ring applications. One potentially important application in this area is as distributed focusing elements installed into very-short-period, small-gap undulators (e.g., as a FODO lattice). The installation is rendered feasible by the very small vertical height of the biplanar N-poles (on the order of a millimeter

  11. Implementation and application of a novel 2D magnetic twisting cytometry based on multi-pole electromagnet.

    PubMed

    Chen, La; Maybeck, Vanessa; Offenhäusser, Andreas; Krause, Hans-Joachim

    2016-06-01

    We implemented a novel 2D magnetic twisting cytometry (MTC) based on a previously reported multi-pole high permeability electromagnet, in which both the strength and direction of the twisting field can be controlled. Thanks to the high performance twisting electromagnet and the heterodyning technology, the measurement frequency has been extended to the 1 kHz range. In order to obtain high remanence of the ferromagnetic beads, a separate electromagnet with feedback control was adopted for the high magnetic field polarization. Our setup constitutes the first instrument which can be operated both in MTC mode and in magnetic tweezers (MT) mode. In this work, the mechanical properties of HL-1 cardiomyocytes were characterized in MTC mode. Both anisotropy and log-normal distribution of cell stiffness were observed, which agree with our previous results measured in MT mode. The response from these living cells at different frequencies can be fitted very well by the soft glassy rheology model.

  12. Fast 3-D large-scale gravity and magnetic modeling using unstructured grids and an adaptive multilevel fast multipole method

    NASA Astrophysics Data System (ADS)

    Ren, Zhengyong; Tang, Jingtian; Kalscheuer, Thomas; Maurer, Hansruedi

    2017-01-01

    A novel fast and accurate algorithm is developed for large-scale 3-D gravity and magnetic modeling problems. An unstructured grid discretization is used to approximate sources with arbitrary mass and magnetization distributions. A novel adaptive multilevel fast multipole (AMFM) method is developed to reduce the modeling time. An observation octree is constructed on a set of arbitrarily distributed observation sites, while a source octree is constructed on a source tetrahedral grid. A novel characteristic is the independence between the observation octree and the source octree, which simplifies the implementation of different survey configurations such as airborne and ground surveys. Two synthetic models, a cubic model and a half-space model with mountain-valley topography, are tested. As compared to analytical solutions of gravity and magnetic signals, excellent agreements of the solutions verify the accuracy of our AMFM algorithm. Finally, our AMFM method is used to calculate the terrain effect on an airborne gravity data set for a realistic topography model represented by a triangular surface retrieved from a digital elevation model. Using 16 threads, more than 5800 billion interactions between 1,002,001 observation points and 5,839,830 tetrahedral elements are computed in 453.6 s. A traditional first-order Gaussian quadrature approach requires 3.77 days. Hence, our new AMFM algorithm not only can quickly compute the gravity and magnetic signals for complicated problems but also can substantially accelerate the solution of 3-D inversion problems.

  13. Magnetic insulation for plasma propulsion

    NASA Technical Reports Server (NTRS)

    Gonzalez, Dora E.

    1990-01-01

    The design parameters of effective magnetic insulation for plasma engines are discussed. An experimental model used to demonstrate the process of plasma acceleration and magnetic insulation is considered which consists of a copper strap that is wound around a glass tube and connected to a capacitor. In order to adequately model the magnetic insulation mechanisms, a computer algorithm is developed. Plasma engines, with their efficient utilization of the propellant mass, are expected to provide the next-generation advanced propulsion systems.

  14. Multipole expansions and intense fields

    NASA Astrophysics Data System (ADS)

    Reiss, Howard R.

    1984-02-01

    In the context of two-body bound-state systems subjected to a plane-wave electromagnetic field, it is shown that high field intensity introduces a distinction between long-wavelength approximation and electric dipole approximation. This distinction is gauge dependent, since it is absent in Coulomb gauge, whereas in "completed" gauges of Göppert-Mayer type the presence of high field intensity makes electric quadrupole and magnetic dipole terms of importance equal to electric dipole at long wavelengths. Another consequence of high field intensity is that multipole expansions lose their utility in view of the equivalent importance of a number of low-order multipole terms and the appearance of large-magnitude terms which defy multipole categorization. This loss of the multipole expansion is gauge independent. Also gauge independent is another related consequence of high field intensity, which is the intimate coupling of center-of-mass and relative coordinate motions in a two-body system.

  15. Process diagnostics and monitoring using the multipole resonance probe in an inhomogeneous plasma for ion-assisted deposition of optical coatings

    NASA Astrophysics Data System (ADS)

    Styrnoll, T.; Harhausen, J.; Lapke, M.; Storch, R.; Brinkmann, R. P.; Foest, R.; Ohl, A.; Awakowicz, P.

    2013-08-01

    The application of a multipole resonance probe (MRP) for diagnostic and monitoring purposes in a plasma ion-assisted deposition (PIAD) process is reported. Recently, the MRP was proposed as an economical and industry compatible plasma diagnostic device (Lapke et al 2011 Plasma Sources Sci. Technol. 20 042001). The major advantages of the MRP are its robustness against dielectric coating and its high sensitivity to measure the electron density. The PIAD process investigated is driven by the advanced plasma source (APS), which generates an ion beam in the deposition chamber for the production of high performance optical coatings. With a background neutral pressure of p0 ˜ 20 mPa the plasma expands from the source region into the recipient, leading to an inhomogeneous spatial distribution. Electron density and electron temperature vary over the distance from substrate (ne ˜ 109 cm-3 and Te,eff ˜ 2 eV) to the APS (ne ≳ 1012 cm-3 and Te,eff ˜ 20 eV) (Harhausen et al 2012 Plasma Sources Sci. Technol. 21 035012). This huge variation of the plasma parameters represents a big challenge for plasma diagnostics to operate precisely for all plasma conditions. The results obtained by the MRP are compared to those from a Langmuir probe chosen as reference diagnostics. It is demonstrated that the MRP is suited for the characterization of the PIAD plasma as well as for electron density monitoring. The latter aspect offers the possibility to develop new control schemes for complex industrial plasma environments.

  16. Studies of plasma confinement in linear and RACETRACK mirror configurations

    SciTech Connect

    Kuthi, A.; Wong, A.Y.

    1986-06-30

    This report discusses research on the following magnetic mirror configurations: Racetrack; ECRH generated plasmas; RF generated plasmas; potential structures; surface multipole fields, and lamex; hot electron physics; axial loss processes; and RF induced effects.

  17. Airfoil-based electromagnetic energy harvester containing parallel array motion between moving coil and multi-pole magnets towards enhanced power density.

    PubMed

    Leung, Chung Ming; Wang, Ya; Chen, Wusi

    2016-11-01

    In this letter, the airfoil-based electromagnetic energy harvester containing parallel array motion between moving coil and trajectory matching multi-pole magnets was investigated. The magnets were aligned in an alternatively magnetized formation of 6 magnets to explore enhanced power density. In particular, the magnet array was positioned in parallel to the trajectory of the tip coil within its tip deflection span. The finite element simulations of the magnetic flux density and induced voltages at an open circuit condition were studied to find the maximum number of alternatively magnetized magnets that was required for the proposed energy harvester. Experimental results showed that the energy harvester with a pair of 6 alternatively magnetized linear magnet arrays was able to generate an induced voltage (Vo) of 20 V, with an open circuit condition, and 475 mW, under a 30 Ω optimal resistance load operating with the wind speed (U) at 7 m/s and a natural bending frequency of 3.54 Hz. Compared to the traditional electromagnetic energy harvester with a single magnet moving through a coil, the proposed energy harvester, containing multi-pole magnets and parallel array motion, enables the moving coil to accumulate a stronger magnetic flux in each period of the swinging motion. In addition to the comparison made with the airfoil-based piezoelectric energy harvester of the same size, our proposed electromagnetic energy harvester generates 11 times more power output, which is more suitable for high-power-density energy harvesting applications at regions with low environmental frequency.

  18. Airfoil-based electromagnetic energy harvester containing parallel array motion between moving coil and multi-pole magnets towards enhanced power density

    NASA Astrophysics Data System (ADS)

    Leung, Chung Ming; Wang, Ya; Chen, Wusi

    2016-11-01

    In this letter, the airfoil-based electromagnetic energy harvester containing parallel array motion between moving coil and trajectory matching multi-pole magnets was investigated. The magnets were aligned in an alternatively magnetized formation of 6 magnets to explore enhanced power density. In particular, the magnet array was positioned in parallel to the trajectory of the tip coil within its tip deflection span. The finite element simulations of the magnetic flux density and induced voltages at an open circuit condition were studied to find the maximum number of alternatively magnetized magnets that was required for the proposed energy harvester. Experimental results showed that the energy harvester with a pair of 6 alternatively magnetized linear magnet arrays was able to generate an induced voltage (Vo) of 20 V, with an open circuit condition, and 475 mW, under a 30 Ω optimal resistance load operating with the wind speed (U) at 7 m/s and a natural bending frequency of 3.54 Hz. Compared to the traditional electromagnetic energy harvester with a single magnet moving through a coil, the proposed energy harvester, containing multi-pole magnets and parallel array motion, enables the moving coil to accumulate a stronger magnetic flux in each period of the swinging motion. In addition to the comparison made with the airfoil-based piezoelectric energy harvester of the same size, our proposed electromagnetic energy harvester generates 11 times more power output, which is more suitable for high-power-density energy harvesting applications at regions with low environmental frequency.

  19. Strongly magnetized classical plasma models

    NASA Technical Reports Server (NTRS)

    Montgomery, D.; Peyraud, J.; Dewitt, C.

    1974-01-01

    Discrete particle processes in the presence of a strong external magnetic field were investigated. These processes include equations of state and other equilibrium thermodynamic relations, thermal relaxation phenomena, transport properties, and microscopic statistical fluctuations in such quantities as the electric field and the charge density. Results from the equilibrium statistical mechanics of two-dimensional plasmas are discussed, along with nonequilibrium statistical mechanics of the electrostatic guiding-center plasma (a two-dimensional plasma model).

  20. Does the magnetic field of a multipole stator winding drive flow of a ferrofluid in a cylindrical container?

    NASA Astrophysics Data System (ADS)

    Torres-Díaz, Isaac; Rinaldi, Carlos

    The flow of a ferrofluid in a stationary cylindrical container driven by a rotating magnetic field has received considerable attention since the inception of the field of ferrohydrodynamics. Much controversy has resulted regarding the existence, or lack thereof, of bulk flow under conditions of a rotating uniform magnetic field, which can be generated for example, using a two-pole stator winding. The original observations of flow at the interface showed counter-rotation of field and fluid, whereas recent observations of bulk flow using the ultrasound technique have shown co-rotation of field and fluid. Various theories have been advanced over the years to explain the observed phenomena, including the spin diffusion theory of Shliomis and the hypothesis that it is field non-uniformity, generated by non-ideal stator winding distributions, that actually drives the flow, as first proposed by Glazov. We have revisited this problem from an analytical perspective by solving the ferrohydrodynamic and magnetoquasistatic equations self-consistently for the case of ferrofluid in a cylindrical container, with and without an internal co-axial cylinder, and driven by the field generated by a multipole stator winding distribution. In such a winding increasing the number of poles results in increasingly non-uniform fields. It is shown that regardless of the number of poles in the stator winding the ferrohydrodynamic equations do not predict any flow in either geometry as long as the spin viscosity parameter is assumed to be zero. Velocity profiles are obtained for both geometries and arbitrary number of poles for the case of non-zero spin viscosity. It is shown that only for the case of a two-pole stator winding and ferrofluid constrained to the annular space between an inner and outer cylinder do the ferrohydrodynamic equations predict co-rotation of fluid and field close to the outer cylinder and counter-rotation of fluid and field close to the inner cylinder, in qualitative

  1. Magnetic multipole induced zero-rotation frequency bounce-resonant loss in a Penning-Malmberg trap used for antihydrogen trapping

    SciTech Connect

    Andresen, G. B.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Joergensen, L. V.; Kerrigan, S. J.; Madsen, N.; Werf, D. P. van der; Bray, C. C.; Chapman, S.; Fajans, J.; Keller, J.; Povilus, A.; Wurtele, J. S.; Cesar, C. L.; Lambo, R.; Fujiwara, M. C.; Gill, D. R.; Kurchaninov, L.

    2009-10-15

    In many antihydrogen trapping schemes, antiprotons held in a short-well Penning-Malmberg trap are released into a longer well. This process necessarily causes the bounce-averaged rotation frequency {omega}{sub r} of the antiprotons around the trap axis to pass through zero. In the presence of a transverse magnetic multipole, experiments and simulations show that many antiprotons (over 30% in some cases) can be lost to a hitherto unidentified bounce-resonant process when {omega}{sub r} is close to zero.

  2. Magnetic Flux Compression in Plasmas

    NASA Astrophysics Data System (ADS)

    Velikovich, A. L.

    2012-10-01

    Magnetic flux compression (MFC) as a method for producing ultra-high pulsed magnetic 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 magnetic 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 magnetic field in a magnetically 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 magnetic 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 magnetic field through plasma. And yet, many experiments stimulated by this proposal since 1986, mostly using pulsed-power drivers, demonstrated reasonably good flux compression up to ˜42 MG, although diagnostics of magnetic 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.

  3. Charge shielding in magnetized plasmas

    SciTech Connect

    Wang Shaojie; Stroth, Ulrich; Van Oost, Guido

    2010-11-15

    The shielding of a charge sheet in a magnetized plasma is investigated by taking account of the diamagnetic drift start-up current in addition to the polarization current. For a charge sheet with an infinitesimal width, the shielding is the same as the conventional Debye shielding if the charge sheet is perpendicular to the magnetic field; the shielding length is {radical}(2) times larger than the conventional one if the charge sheet is parallel to the magnetic field. When the scale length of the charge sheet is comparable or smaller than the ion Larmor radius, the electric field is significantly enhanced within the charge sheet, while far away from the charge sheet, the electric field is shielded to the usual 1/{epsilon}{sub r} level (where {epsilon}{sub r} is the diamagnetic coefficient of the magnetized plasma).

  4. Studies of plasma confinement in linear and RACETRACK mirror configurations. Progress report, January 1--October 31, 1986

    SciTech Connect

    Kuthi, A.; Wong, A.Y.

    1986-06-30

    This report discusses research on the following magnetic mirror configurations: Racetrack; ECRH generated plasmas; RF generated plasmas; potential structures; surface multipole fields, and lamex; hot electron physics; axial loss processes; and RF induced effects.

  5. Measurement of Electron Density Using the Multipole Resonance Probe, Langmuir Probe and Optical Emission Spectroscopy in Low Pressure Plasmas with Different Electron Energy Distribution Functions

    NASA Astrophysics Data System (ADS)

    Oberberg, Moritz; Bibinov, Nikita; Ries, Stefan; Awakowicz, Peter; Institute of Electrical Engineering; Plasma Technology Team

    2016-09-01

    In recently publication, the young diagnostic tool Multipole Resonance Probe (MRP) for electron density measurements was introduced. It is based on active plasma resonance spectroscopy (APRS). The probe was simulated und evaluated for different devices. The geometrical and electrical symmetry simplifies the APRS model, so that the electron density can be easily calculated from the measured resonance. In this work, low pressure nitrogen mixture plasmas with different electron energy distribution functions (EEDF) are investigated. The results of the MRP measurement are compared with measurements of a Langmuir Probe (LP) and Optical Emission Spectroscopy (OES). Probes and OES measure in different regimes of kinetic electron energy. Both probes measure electrons with low kinetic energy (<10 eV), whereas the OES is influenced by electrons with high kinetic energy which are needed for transitions of molecule bands. By the determination of the absolute intensity of N2(C-B) and N2+(B-X)electron temperature and density can be calculated. In a non-maxwellian plasma, all plasma diagnostics need to be combined.

  6. 15 cm multipole gas ion thruster

    NASA Technical Reports Server (NTRS)

    Isaacson, G. C.; Kaufman, H. R.

    1976-01-01

    A 15-cm multipole thruster was operated on argon and xenon. The multipole approach used has been shown capable of low discharge losses and flat ion beam profiles with a minimum of redesign. This approach employs low magnetic field strengths and flat or cylindrical sheet-metal parts, hence is suited to rapid optimization and scaling. Only refractory metal cathodes were used in this investigation.

  7. Fully magnetized plasma flow in a magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Merino, Mario; Ahedo, Eduardo

    2016-02-01

    A model of the expansion of a plasma in a magnetic nozzle in the full magnetization limit is presented. The fully magnetized and the unmagnetized-ions limits are compared, recovering the whole range of variability in plasma properties, thrust, and plume efficiency, and revealing the differences in the physics of the two cases. The fully magnetized model is the natural limit of the general, 2D, two-fluid model of Ahedo and Merino [Phys. Plasmas 17, 073501 (2010)], and it is proposed as an analytical, conservative estimator of the propulsive figures of merit of partially magnetized plasma expansions in the near region of the magnetic nozzle.

  8. Two-Dimensional Turbulence in Magnetized Plasmas

    ERIC Educational Resources Information Center

    Kendl, A.

    2008-01-01

    In an inhomogeneous magnetized plasma the transport of energy and particles perpendicular to the magnetic field is in general mainly caused by quasi two-dimensional turbulent fluid mixing. The physics of turbulence and structure formation is of ubiquitous importance to every magnetically confined laboratory plasma for experimental or industrial…

  9. Magnetic Detachment and Plume Control in Escaping Magnetized Plasma

    SciTech Connect

    P. F. Schmit and N. J. Fisch

    2008-11-05

    The model of two-fluid, axisymmetric, ambipolar magnetized plasma detachment from thruster guide fields is extended to include plasmas with non-zero injection angular velocity profiles. Certain plasma injection angular velocity profiles are shown to narrow the plasma plume, thereby increasing exhaust efficiency. As an example, we consider a magnetic guide field arising from a simple current ring and demonstrate plasma injection schemes that more than double the fraction of useful exhaust aperture area, more than halve the exhaust plume angle, and enhance magnetized plasma detachment.

  10. Runaway tails in magnetized plasmas

    NASA Technical Reports Server (NTRS)

    Moghaddam-Taaheri, E.; Vlahos, L.; Rowland, H. L.; Papadopoulos, K.

    1985-01-01

    The evolution of a runaway tail driven by a dc electric field in a magnetized plasma is analyzed. Depending on the strength of the electric field and the ratio of plasma to gyrofrequency, there are three different regimes in the evolution of the tail. The tail can be (1) stable with electrons accelerated to large parallel velocities, (2) unstable to Cerenkov resonance because of the depletion of the bulk and the formation of a positive slope, (3) unstable to the anomalous Doppler resonance instability driven by the large velocity anisotropy in the tail. Once an instability is triggered (Cerenkov or anomalous Doppler resonance) the tail relaxes into an isotropic distribution. The role of a convection type loss term is also discussed.

  11. Macroscopic magnetic islands and plasma energy transport

    SciTech Connect

    Cima, G; Porcelli, F; Rossi, E; Wootton, A J

    1998-12-03

    A model is presented, based on the combined effects of m=n=l magnetic island dynamics, localized heat sources, large heat diffusivity along magnetic field lines and plasma rotation, which may explain the multipeaked temperature profiles and transport barriers observed in tokamak plasmas heated by electron cyclotron resonant waves.

  12. Magnetic Turbulence in colliding laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Gekelman, Walter; Collette, Andrew

    2006-10-01

    We describe a series of experiments, which involve the collision of two dense (initially, δnlpp/n0>>1) laser-produced plasmas (llp) within an ambient, highly magnetized (Rciplasma) capable of supporting Alfvén waves. Colliding plasmas can be used to study generation of magnetic turbulence and spontaneous generation of magnetic fields. The plasma column (He, Ne, 1-4 X10^12 cm^3) is 18 m long and 60 cm in diameter, 15 ms duration and pulsed at 1 Hz. Two carbon targets are struck by 1.5 J (10 ns,10 μ, 1 Hz) laser beams. The lpp's form diamagnetic bubbles in which a large percentage of the background magnetic field (600G magnetic field and collide. Fast camera (3 ns) photographs show the bubble surfaces become corrugated after the collision. Small magnetic field probes are used to study the magnetic turbulence. One probe is fixed and the second moved in a small volume close to the targets. An ensemble each location within the volume is used to determine correlations and cross-spectral functions of the magnetic turbulence. The current systems of the waves are fully three-dimensional and are reported in the adjacent poster by Collette et al. [1] M. Van Zeeland, W. Gekelman, Laser Plasma Diamagnetism in the presence of an ambient magnetized plasma, Phys. Plasmas, 11, 320 (2004)

  13. Reflection and refraction of multipole radiation by an interface.

    PubMed

    Arnoldus, Henk F

    2005-01-01

    Reflection and refraction of electromagnetic multipole radiation by an interface is studied. The multipole can be electric or magnetic and is of arbitrary order (dipole, quadrupole). From the angular spectrum representation of the radiation emitted by the multipole, I have obtained the angular spectrum representations of the reflected and transmitted fields, which involve the Fresnel reflection and transmission coefficients. The intensity distribution in the far field is evaluated with the method of stationary phase. The result is very simple in appearance and can be expressed in terms of two auxiliary functions of a complex variable. By exchanging the Fresnel coefficients for s and p polarization, the result for an electric multipole can be obtained from the result for a magnetic multipole.

  14. Plasma confinement. [Physics for magnetic geometries

    SciTech Connect

    Boozer, A.H.

    1985-03-01

    The physics of plasma confinement by a magnetic field is developed from the basic properties of plasmas through the theory of equilibrium, stability, and transport in toroidal and open-ended configurations. The close relationship between the theory of plasma confinement and Hamiltonian mechanics is emphasized, and the modern view of macroscopic instabilities as three-dimensional equilibria is given.

  15. Magnetic field penetration of erosion switch plasmas

    NASA Astrophysics Data System (ADS)

    Mason, Rodney J.; Jones, Michael E.; Grossmann, John M.; Ottinger, Paul F.

    1988-10-01

    Computer simulations demonstrate that the entrainment (or advection) of magnetic field with the flow of cathode-emitted electrons can constitute a dominant mechanism for the magnetic field penetration of erosion switch plasmas. Cross-field drift in the accelerating electric field near the cathode starts the penetration process. Plasma erosion propagates the point for emission and magnetic field injection along the cathode toward the load-for the possibility of rapid switch opening.

  16. Permanent Magnet Ecr Plasma Source With Magnetic Field Optimization

    DOEpatents

    Doughty, Frank C.; Spencer, John E.

    2000-12-19

    In a plasma-producing device, an optimized magnet field for electron cyclotron resonance plasma generation is provided by a shaped pole piece. The shaped pole piece adjusts spacing between the magnet and the resonance zone, creates a convex or concave resonance zone, and decreases stray fields between the resonance zone and the workpiece. For a cylindrical permanent magnet, the pole piece includes a disk adjacent the magnet together with an annular cylindrical sidewall structure axially aligned with the magnet and extending from the base around the permanent magnet. The pole piece directs magnetic field lines into the resonance zone, moving the resonance zone further from the face of the magnet. Additional permanent magnets or magnet arrays may be utilized to control field contours on a local scale. Rather than a permeable material, the sidewall structure may be composed of an annular cylindrical magnetic material having a polarity opposite that of the permanent magnet, creating convex regions in the resonance zone. An annular disk-shaped recurve section at the end of the sidewall structure forms magnetic mirrors keeping the plasma off the pole piece. A recurve section composed of magnetic material having a radial polarity forms convex regions and/or magnetic mirrors within the resonance zone.

  17. Magnetic Field Effects on Plasma Plumes

    NASA Technical Reports Server (NTRS)

    Ebersohn, F.; Shebalin, J.; Girimaji, S.; Staack, D.

    2012-01-01

    Here, we will discuss our numerical studies of plasma jets and loops, of basic interest for plasma propulsion and plasma astrophysics. Space plasma propulsion systems require strong guiding magnetic fields known as magnetic nozzles to control plasma flow and produce thrust. Propulsion methods currently being developed that require magnetic nozzles include the VAriable Specific Impulse Magnetoplasma Rocket (VASIMR) [1] and magnetoplasmadynamic thrusters. Magnetic nozzles are functionally similar to de Laval nozzles, but are inherently more complex due to electromagnetic field interactions. The two crucial physical phenomenon are thrust production and plasma detachment. Thrust production encompasses the energy conversion within the nozzle and momentum transfer to a spacecraft. Plasma detachment through magnetic reconnection addresses the problem of the fluid separating efficiently from the magnetic field lines to produce maximum thrust. Plasma jets similar to those of VASIMR will be studied with particular interest in dual jet configurations, which begin as a plasma loops between two nozzles. This research strives to fulfill a need for computational study of these systems and should culminate with a greater understanding of the crucial physics of magnetic nozzles with dual jet plasma thrusters, as well as astrophysics problems such as magnetic reconnection and dynamics of coronal loops.[2] To study this problem a novel, hybrid kinetic theory and single fluid magnetohydrodynamic (MHD) solver known as the Magneto-Gas Kinetic Method is used.[3] The solver is comprised of a "hydrodynamic" portion based on the Gas Kinetic Method and a "magnetic" portion that accounts for the electromagnetic behaviour of the fluid through source terms based on the resistive MHD equations. This method is being further developed to include additional physics such as the Hall effect. Here, we will discuss the current level of code development, as well as numerical simulation results

  18. Directed Plasma Flow across Magnetic Field

    NASA Astrophysics Data System (ADS)

    Presura, R.; Stepanenko, Y.; Neff, S.; Sotnikov, V. I.

    2008-04-01

    The Hall effect plays a significant role in the penetration of plasma flows across magnetic field. For example, its effect may become dominant in the solar wind penetration into the magnetosphere, in the magnetic field advection in wire array z-pinch precursors, or in the arcing of magnetically insulated transmission lines. An experiment performed at the Nevada Terawatt Facility explored the penetration of plasma with large Hall parameter (˜10) across ambient magnetic field. The plasma was produced by ablation with the short pulse high intensity laser Leopard (0.35 ps, 10^17W/cm^2) and the magnetic field with the pulsed power generator Zebra (50 T). The expanding plasma assumed a jet configuration and propagated beyond a distance consistent with a diamagnetic bubble model. Without magnetic field, the plasma expansion was close to hemispherical. The ability to produce the plasma and the magnetic field with distinct generators allows a controlled, quasi-continuous variation of the Hall parameter and other plasma parameters making the experiments useful for benchmarking numerical simulations.

  19. Magnetic circuit for hall effect plasma accelerator

    NASA Technical Reports Server (NTRS)

    Manzella, David H. (Inventor); Jacobson, David T. (Inventor); Jankovsky, Robert S. (Inventor); Hofer, Richard (Inventor); Peterson, Peter (Inventor)

    2009-01-01

    A Hall effect plasma accelerator includes inner and outer electromagnets, circumferentially surrounding the inner electromagnet along a thruster centerline axis and separated therefrom, inner and outer magnetic conductors, in physical connection with their respective inner and outer electromagnets, with the inner magnetic conductor having a mostly circular shape and the outer magnetic conductor having a mostly annular shape, a discharge chamber, located between the inner and outer magnetic conductors, a magnetically conducting back plate, in magnetic contact with the inner and outer magnetic conductors, and a combined anode electrode/gaseous propellant distributor, located at a bottom portion of the discharge chamber. The inner and outer electromagnets, the inner and outer magnetic conductors and the magnetically conducting back plate form a magnetic circuit that produces a magnetic field that is largely axial and radially symmetric with respect to the thruster centerline.

  20. An O(N) and parallel approach to integral problems by a kernel-independent fast multipole method: Application to polarization and magnetization of interacting particles

    NASA Astrophysics Data System (ADS)

    Jiang, Xikai; Li, Jiyuan; Zhao, Xujun; Qin, Jian; Karpeev, Dmitry; Hernandez-Ortiz, Juan; de Pablo, Juan J.; Heinonen, Olle

    2016-08-01

    Large classes of materials systems in physics and engineering are governed by magnetic and electrostatic interactions. Continuum or mesoscale descriptions of such systems can be cast in terms of integral equations, whose direct computational evaluation requires O(N2) operations, where N is the number of unknowns. Such a scaling, which arises from the many-body nature of the relevant Green's function, has precluded wide-spread adoption of integral methods for solution of large-scale scientific and engineering problems. In this work, a parallel computational approach is presented that relies on using scalable open source libraries and utilizes a kernel-independent Fast Multipole Method (FMM) to evaluate the integrals in O(N) operations, with O(N) memory cost, thereby substantially improving the scalability and efficiency of computational integral methods. We demonstrate the accuracy, efficiency, and scalability of our approach in the context of two examples. In the first, we solve a boundary value problem for a ferroelectric/ferromagnetic volume in free space. In the second, we solve an electrostatic problem involving polarizable dielectric bodies in an unbounded dielectric medium. The results from these test cases show that our proposed parallel approach, which is built on a kernel-independent FMM, can enable highly efficient and accurate simulations and allow for considerable flexibility in a broad range of applications.

  1. An O(N) and parallel approach to integral problems by a kernel-independent fast multipole method: Application to polarization and magnetization of interacting particles

    DOE PAGES

    Jiang, Xikai; Li, Jiyuan; Zhao, Xujun; ...

    2016-08-10

    Large classes of materials systems in physics and engineering are governed by magnetic and electrostatic interactions. Continuum or mesoscale descriptions of such systems can be cast in terms of integral equations, whose direct computational evaluation requires O(N2) operations, where N is the number of unknowns. Such a scaling, which arises from the many-body nature of the relevant Green's function, has precluded wide-spread adoption of integral methods for solution of large-scale scientific and engineering problems. In this work, a parallel computational approach is presented that relies on using scalable open source libraries and utilizes a kernel-independent Fast Multipole Method (FMM) tomore » evaluate the integrals in O(N) operations, with O(N) memory cost, thereby substantially improving the scalability and efficiency of computational integral methods. We demonstrate the accuracy, efficiency, and scalability of our approach in the context of two examples. In the first, we solve a boundary value problem for a ferroelectric/ferromagnetic volume in free space. In the second, we solve an electrostatic problem involving polarizable dielectric bodies in an unbounded dielectric medium. Lastly, the results from these test cases show that our proposed parallel approach, which is built on a kernel-independent FMM, can enable highly efficient and accurate simulations and allow for considerable flexibility in a broad range of applications.« less

  2. Curling probe measurement of large-volume pulsed plasma confined by surface magnetic field

    NASA Astrophysics Data System (ADS)

    Pandey, Anil; Sakakibara, Wataru; Matsuoka, Hiroyuki; Nakamura, Keiji; Sugai, Hideo; Chubu University Team; DOWA Thermotech Collaboration

    2015-09-01

    Curling probe (CP) has recently been developed which enables the local electron density measurement even in plasma for non-conducting film CVD. The electron density is obtained from a shift of resonance frequency of spiral antenna in discharge ON and OFF monitored by a network analyzer (NWA). In case of a pulsed glow discharge, synchronization of discharge pulse with frequency sweep of NWA must be established. In this paper, we report time and space-resolved CP measurement of electron density in a large volume plasma (80 cm diameter, 110 cm length) confined by surface magnetic field (multipole cusp field ~0.03 T). For plasma-aided modification of metal surface, the plasma is produced by 1 kV glow discharge at pulse frequency of 0.3 - 25 kHz with various duty ratio in gas (Ar, N2, C2H2) at pressure ~ 1 Pa. A radially movable CP revealed a remarkable effect of surface magnetic confinement: detach of plasma from the vessel wall and a fairly uniform plasma in the central region. In afterglow phase, the electron density was observed to decrease much faster in C2H2 discharge than in Ar discharge.

  3. Forced Magnetic Reconnection In A Tokamak Plasma

    NASA Astrophysics Data System (ADS)

    Callen, J. D.; Hegna, C. C.

    2015-11-01

    The theory of forced magnetic field reconnection induced by an externally imposed resonant magnetic perturbation usually uses a sheared slab or cylindrical magnetic field model and often focuses on the potential time-asymptotic induced magnetic island state. However, tokamak plasmas have significant magnetic geometry and dynamical plasma toroidal rotation screening effects. Also, finite ion Larmor radius (FLR) and banana width (FBW) effects can damp and thus limit the width of a nascent magnetic island. A theory that is more applicable for tokamak plasmas is being developed. This new model of the dynamics of forced magnetic reconnection considers a single helicity magnetic perturbation in the tokamak magnetic field geometry, uses a kinetically-derived collisional parallel electron flow response, and employs a comprehensive dynamical equation for the plasma toroidal rotation frequency. It is being used to explore the dynamics of bifurcation into a magnetically reconnected state in the thin singular layer around the rational surface, evolution into a generalized Rutherford regime where the island width exceeds the singular layer width, and assess the island width limiting effects of FLR and FBW polarization currents. Support by DoE grants DE-FG02-86ER53218, DE-FG02-92ER54139.

  4. Target Plasma Formation for Magnetic Compression/Magnetized Target Fusion

    NASA Astrophysics Data System (ADS)

    Lindemuth, I. R.; Reinovsky, R. E.; Chrien, R. E.; Christian, J. M.; Ekdahl, C. A.; Goforth, J. H.; Haight, R. C.; Idzorek, G.; King, N. S.; Kirkpatrick, R. C.; Larson, R. E.; Morgan, G. L.; Olinger, B. W.; Oona, H.; Sheehey, P. T.; Shlachter, J. S.; Smith, R. C.; Veeser, L. R.; Warthen, B. J.; Younger, S. M.; Chernyshev, V. K.; Mokhov, V. N.; Demin, A. N.; Dolin, Y. N.; Garanin, S. F.; Ivanov, V. A.; Korchagin, V. P.; Mikhailov, O. D.; Morozov, I. V.; Pak, S. V.; Pavlovskii, E. S.; Seleznev, N. Y.; Skobelev, A. N.; Volkov, G. I.; Yakubov, V. A.

    1995-09-01

    Experimental observations of plasma behavior in a novel plasma formation chamber are reported. Experimental results are in reasonable agreement with two-dimensional magnetohydrodynamic computations suggesting that the plasma could subsequently be adiabatically compressed by a magnetically driven pusher to yield 1 GJ of fusion energy. An explosively driven helical flux compression generator mated with a unique closing switch/opening switch combination delivered a 2.7 MA, 347 μs magnetization current and an additional 5 MA, 2.5 μs electrical pulse to the chamber. A hot plasma was produced and 1013 D-T fusion reactions were observed.

  5. Simulation of Magnetic Field Guided Plasma Expansion

    NASA Astrophysics Data System (ADS)

    Ebersohn, Frans; Sheehan, J. P.; Gallimore, Alec; Shebalin, John

    2015-09-01

    Magnetic field guided expansion of a radio-frequency plasma was simulated with a quasi-one-dimensional particle-in-cell code. Two-dimensional effects were included in a one-dimensional particle-in-cell code by varying the cross-sectional area of the one dimensional domain and including forces due to the magnetic field. Acceleration of electrons by the magnetic field forces leads to the formation of potential structures which then accelerate the ions into a beam. Density changes due to the plasma expansion only weakly affect the ion acceleration. Rapidly diverging magnetic fields lead to more rapid acceleration and the electrons cool as they expand.

  6. Magnetic Nozzle and Plasma Detachment Experiment

    NASA Technical Reports Server (NTRS)

    Chavers, Gregory; Dobson, Chris; Jones, Jonathan; Martin, Adam; Bengtson, Roger D.; Briezman, Boris; Arefiev, Alexey; Cassibry, Jason; Shuttpelz, Branwen; Deline, Christopher

    2006-01-01

    High power plasma propulsion can move large payloads for orbit transfer (such as the ISS), lunar missions, and beyond with large savings in fuel consumption owing to the high specific impulse. At high power, lifetime of the thruster becomes an issue. Electrodeless devices with magnetically guided plasma offer the advantage of long life since magnetic fields confine the plasma radially and keep it from impacting the material surfaces. For decades, concerns have been raised about the plasma remaining attached to the magnetic field and returning to the vehicle along the closed magnetic field lines. Recent analysis suggests that this may not be an issue of the magnetic field is properly shaped in the nozzle region and the plasma has sufficient energy density to stretch the magnetic field downstream. An experiment was performed to test the theory regarding the Magneto-hydrodynamic (MHD) detachment scenario. Data from this experiment will be presented. The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) being developed by the Ad Astra Rocket Company uses a magnetic nozzle as described above. The VASIMR is also a leading candidate for exploiting an electric propulsion test platform being considered for the ISS.

  7. Magnetically driven flows in arched plasma structures.

    PubMed

    Stenson, E V; Bellan, P M

    2012-08-17

    Laboratory experiments demonstrate high-speed plasma flows from both footpoints of arched magnetic flux tubes, resulting in bulk plasma transport into the flux tube and persistent axial collimation even as the flux tube lengthens and kinks. The measured flows are in agreement with the predictions of hoop force and collimation models involving fundamental MHD forces. These forces are expected to drive plasma acceleration in other open flux configurations with arched geometries, such as those found on the solar surface.

  8. Magnetic Flux Compression Experiments Using Plasma Armatures

    NASA Technical Reports Server (NTRS)

    Turner, M. W.; Hawk, C. W.; Litchford, R. J.

    2003-01-01

    Magnetic flux 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 magnetic flux 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 magnetic Reynolds number (R(sub m), the value of which depends upon the product of plasma electrical conductivity and velocity. Efficient flux compression requires R(sub m) less than 1, and a thorough understanding of MHD phenomena at high magnetic 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 magnetic fields. As a prelude to intensive study, exploratory experiments were carried out to quantify the magnetic 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.

  9. Plasma Hole -- a Singular Vortex in a Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Tanaka, M. Y.

    2008-12-01

    A vortex with a density cavity in its core has been observed in a magnetized cylindrical plasma. It is called "plasma hole" from the visual impression when viewed along the axis of the vortex. The flow velocity measurements revealed that the plasma hole accompanies with supersonic azimuthal flow and radial flow toward the center, on a plane perpendicular to the magnetic field. The vorticity distribution evaluated from the flow velocity field is localized near the vortex center axis. This vorticity localization is identified as a Burgers vortex, which is the first observation of Burgers vortex in a plasma. The plasma hole is divided into two regions; in the peripheral regions the Lorentz force is balanced with the electric force (ExB drift), and in the core regions the Lorentz force is balanced with the centrifugal force. Rotation driven by centrifugal force is called fast rotation, and is realized only in non-neutral plasmas so far. It is found that charge neutrality condition in the core region breaks down by three order of magnitude compared with the case without plasma hole (10-6). The effective viscosity in the core region exhibits an anomaly as well. The detailed experimental results on the plasma hole and the implication from the viewpoint of basic plasma physics will be presented. Note from Publisher: This article contains the abstract only.

  10. Advanced UXO Detection and Discrimination Using Magnetic Data Based on Extended Euler Deconvolution and Shape Identification Through Multipole Moments

    DTIC Science & Technology

    2011-04-01

    magnetic data, whether observed or not by the eye . The inversion has appropriately ignored these features and the resulting data fit indicates...Low Frequency Electromagnetics. DRES Special Publication SSP 124. Defence Research Establishment Suffield Ralston, Alberta. McFee, J. E. and Das, Y

  11. A model of magneto-electric multipoles.

    PubMed

    Lovesey, S W; Balcar, E

    2015-03-18

    A long-known Hamiltonian of electrons with entangled spin and orbital degrees of freedom is re-examined as a model of magneto-electric multipoles (MEs). In the model, a magnetic charge and simple quantum rotator are tightly locked in action, some might say they are enslaved entities. It is shown that MEs almost perfectly accord with those inferred from an analysis of magnetic neutron diffraction data on a ceramic superconductor (YBCO) in the pseudo-gap phase. Nigh on perfection between Stone's model and inferred MEs is achieved by addition to the original model of a crystal-field potential appropriate for the magnetic space group used in the published data analysis. An impression of thermal properties of multipoles is sought from a molecular-field model.

  12. Collisionless Coupling between Explosive Debris Plasma and Magnetized Ambient Plasma

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton

    2016-10-01

    The explosive expansion of a dense debris plasma cloud into relatively tenuous, magnetized, ambient plasma characterizes a wide variety of astrophysical and space phenomena, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these rarified environments, collective electromagnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris plasma to the ambient plasma. In an effort to better understand the detailed physics of collisionless coupling mechanisms in a reproducible laboratory setting, the present research jointly utilizes the Large Plasma Device (LAPD) and the Phoenix laser facility at UCLA to study the super-Alfvénic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and magnetic field induction probes. Large Doppler shifts detected in a He II ion spectral line directly indicate initial ambient ion acceleration transverse to both the debris plasma flow and the background magnetic field, indicative of a fundamental process known as Larmor coupling. Characterization of the laser-produced debris plasma via a radiation-hydrodynamics code permits an explicit calculation of the laminar electric field in the framework of a ``hybrid'' model (kinetic ions, charge-neutralizing massless fluid electrons), thus allowing for a simulation of the initial response of a distribution of He II test ions. A synthetic Doppler-shifted spectrum constructed from the simulated velocity distribution of the accelerated test ions excellently reproduces the spectroscopic measurements, confirming the role of Larmor coupling in the debris-ambient interaction.

  13. Local thermodynamics of a magnetized, anisotropic plasma

    SciTech Connect

    Hazeltine, R. D.; Mahajan, S. M.; Morrison, P. J.

    2013-02-15

    An expression for the internal energy of a fluid element in a weakly coupled, magnetized, anisotropic plasma is derived from first principles. The result is a function of entropy, particle density and magnetic field, and as such plays the role of a thermodynamic potential: it determines in principle all thermodynamic properties of the fluid element. In particular it provides equations of state for the magnetized plasma. The derivation uses familiar fluid equations, a few elements of kinetic theory, the MHD version of Faraday's law, and certain familiar stability and regularity conditions.

  14. Electron Cooling in a Magnetically Expanding Plasma.

    PubMed

    Little, J M; Choueiri, E Y

    2016-11-25

    Electron cooling in a magnetically expanding plasma, which is a fundamental process for plasma flow and detachment in magnetic nozzles, is experimentally investigated using a radio frequency plasma source and magnetic nozzle (MN). Probe measurements of the plasma density, potential, and electron temperature along the center line of the MN indicate that the expansion follows a polytropic law with exponent γ_{e}=1.15±0.03. This value contradicts isothermal electron expansion, γ_{e}=1, which is commonly assumed in MN models. The axial variation of the measured quantities can be described by a simple quasi-1D fluid model with classical electron thermal conduction, for which it has been previously shown that a value of γ_{e}≈1.19 is expected in the weakly collisional limit. A new criterion, derived from the model, ensures efficient ion acceleration when a critical value for the ratio of convected to conducted power is exceeded.

  15. Optical magnetic plasma in artificial flowers.

    PubMed

    Li, Jingjing; Thylen, Lars; Bratkovsky, Alexander; Wang, Shiy-Yuan; Williams, R Stanley

    2009-06-22

    We report the design of an artificial flower-like structure that supports a magnetic plasma in the optical domain. The structure is composed of alternating "petals" of conventional dielectrics (epsilon > 0) and plasmonic materials (Re(epsilon ) < 0). The induced effective magnetic current on such a structure possesses a phase lag with respect to the incident TE-mode magnetic field, similar to the phase lag between the induced electric current and the incident TM-mode electric field on a metal wire. An analogy is thus drawn with an artificial electric plasma composed of metal wires driven by a radio frequency excitation. The effective medium of an array of flowers has a negative permeability within a certain wavelength range, thus behaving as a magnetic plasma.

  16. Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Eskridge, Richard; Smith, James; Lee, Michael; Richeson, Jeff; Schmidt, George; Knapp, Charles E.; Kirkpatrick, Ronald C.; Turchi, Peter J.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    Magnetized target fusion (MTF) attempts to combine the favorable attributes of magnetic confinement fusion (MCF) for energy confinement with the attributes of inertial confinement fusion (ICF) for efficient compression heating and wall-free containment of the fusing plasma. It uses a material liner to compress and contain a magnetized plasma. For practical applications, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC). For the successful implementation of the scheme, plasma jets of the requisite momentum flux density need to be produced. Their transport over sufficiently large distances (a few meters) needs to be assured. When they collide and merge into a liner, relative differences in velocity, density and temperature of the jets could give rise to instabilities in the development of the liner. Variation in the jet properties must be controlled to ensure that the growth rate of the instabilities are not significant over the time scale of the liner formation before engaging with the target plasma. On impact with the target plasma, some plasma interpenetration might occur between the liner and the target. The operating parameter space needs to be identified to ensure that a reasonably robust and conducting contact surface is formed between the liner and the target. A mismatch in the "impedance" between the liner and the target plasma could give rise to undesirable shock heating of the liner leading to increased entropy (thermal losses) in the liner. Any irregularities in the liner will accentuate the Rayleigh-Taylor instabilities during the compression of the target plasma by the liner.

  17. Momentum transfer to rotating magnetized plasma from gun plasma injection

    SciTech Connect

    Shamim, Imran; Hassam, A. B.; Ellis, R. F.; Witherspoon, F. D.; Phillips, M. W.

    2006-11-15

    Numerical simulations are carried out to investigate the penetration and momentum coupling of a gun-injected plasma slug into a rotating magnetized plasma. An experiment along these lines is envisioned for the Maryland Centrifugal Experiment (MCX) [R. F. Ellis et al., Phys. Plasmas 8, 2057 (2001)] using a coaxial plasma accelerator gun developed by HyperV Technologies Corp. [F. D. Witherspoon et al., Bull. Am. Phys. Soc. 50, LP1 87 (2005)]. The plasma gun would be located in the axial midplane and fired off-axis into the rotating MCX plasma annulus. The numerical simulation is set up so that the initial momentum in the injected plasma slug is of the order of the initial momentum of the target plasma. Several numerical firings are done into the cylindrical rotating plasma. Axial symmetry is assumed. The slug is seen to penetrate readily and deform into a mushroom, characteristic of interchange deformations. It is found that up to 25% of the momentum in the slug can be transferred to the background plasma in one pass across a cylindrical chord. For the same initial momentum, a high-speed low density slug gives more momentum transfer than a low-speed high density slug. Details of the numerical simulations and a scaling study are presented.

  18. Dynamics of exploding plasmas in a large magnetized plasma

    SciTech Connect

    Niemann, C.; Gekelman, W.; Constantin, C. G.; Everson, E. T.; Schaeffer, D. B.; Clark, S. E.; Zylstra, A. B.; Pribyl, P.; Tripathi, S. K. P.; Bondarenko, A. S.; Winske, D.; Larson, D.; Glenzer, S. H.

    2013-01-15

    The dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma was investigated with magnetic flux probes and Langmuir probes. Debris-ions expanding at super-Alfvenic velocity (up to M{sub A}=1.5) expel the ambient magnetic field, creating a large (>20 cm) diamagnetic cavity. We observe a field compression of up to B/B{sub 0}=1.5 as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized by the magnetic piston and swept outside the bubble volume. Nonlinear shear-Alfven waves ({delta}B/B{sub 0}>25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave.

  19. Integrity of the Plasma Magnetic Nozzle

    NASA Technical Reports Server (NTRS)

    Gerwin, Richard A.

    2009-01-01

    This report examines the physics governing certain aspects of plasma propellant flow through a magnetic nozzle, specifically the integrity of the interface between the plasma and the nozzle s magnetic field. The injection of 100s of eV plasma into a magnetic flux nozzle that converts thermal energy into directed thrust is fundamental to enabling 10 000s of seconds specific impulse and 10s of kW/kg specific power piloted interplanetary propulsion. An expression for the initial thickness of the interface is derived and found to be approx.10(exp -2) m. An algorithm is reviewed and applied to compare classical resistivity to gradient-driven microturbulent (anomalous) resistivity, in terms of the spatial rate and time integral of resistive interface broadening, which can then be related to the geometry of the nozzle. An algorithm characterizing plasma temperature, density, and velocity dependencies is derived and found to be comparable to classical resistivity at local plasma temperatures of approx. 200 eV. Macroscopic flute-mode instabilities in regions of "adverse magnetic curvature" are discussed; a growth rate formula is derived and found to be one to two e-foldings of the most unstable Rayleigh-Taylor (RT) mode. After establishing the necessity of incorporating the Hall effect into Ohm s law (allowing full Hall current to flow and concomitant plasma rotation), a critical nozzle length expression is derived in which the interface thickness is limited to about 1 ion gyroradius.

  20. Magnetic field amplification in turbulent astrophysical plasmas

    NASA Astrophysics Data System (ADS)

    Federrath, Christoph

    2016-12-01

    Magnetic fields play an important role in astrophysical accretion discs and in the interstellar and intergalactic medium. They drive jets, suppress fragmentation in star-forming clouds and can have a significant impact on the accretion rate of stars. However, the exact amplification mechanisms of cosmic magnetic fields remain relatively poorly understood. Here, I start by reviewing recent advances in the numerical and theoretical modelling of the turbulent dynamo, which may explain the origin of galactic and intergalactic magnetic fields. While dynamo action was previously investigated in great detail for incompressible plasmas, I here place particular emphasis on highly compressible astrophysical plasmas, which are characterised by strong density fluctuations and shocks, such as the interstellar medium. I find that dynamo action works not only in subsonic plasmas, but also in highly supersonic, compressible plasmas, as well as for low and high magnetic Prandtl numbers. I further present new numerical simulations from which I determine the growth of the turbulent (un-ordered) magnetic field component ( turb$ ) in the presence of weak and strong guide fields ( 0$ ). I vary 0$ over five orders of magnitude and find that the dependence of turb$ on 0$ is relatively weak, and can be explained with a simple theoretical model in which the turbulence provides the energy to amplify turb$ . Finally, I discuss some important implications of magnetic fields for the structure of accretion discs, the launching of jets and the star-formation rate of interstellar clouds.

  1. Heat flux viscosity in collisional magnetized plasmas

    SciTech Connect

    Liu, C.; Fox, W.; Bhattacharjee, A.

    2015-05-15

    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, 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-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux 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.

  2. High density plasma etching of magnetic devices

    NASA Astrophysics Data System (ADS)

    Jung, Kee Bum

    Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this has limitations for magnetic structures with submicron dimensions. In this dissertation, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma) for the etching of magnetic materials (NiFe, NiFeCo, CoFeB, CoSm, CoZr) and other related materials (TaN, CrSi, FeMn), which are employed for magnetic devices like magnetoresistive random access memories (MRAM), magnetic read/write heads, magnetic sensors and microactuators. This research examined the fundamental etch mechanisms occurring in high density plasma processing of magnetic materials by measuring etch rate, surface morphology and surface stoichiometry. However, one concern with using Cl2-based plasma chemistry is the effect of residual chlorine or chlorinated etch residues remaining on the sidewalls of etched features, leading to a degradation of the magnetic properties. To avoid this problem, we employed two different processing methods. The first one is applying several different cleaning procedures, including de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas. Very stable magnetic properties were achieved over a period of ˜6 months except O2 plasma treated structures, with no evidence of corrosion, provided chlorinated etch residues were removed by post-etch cleaning. The second method is using non-corrosive gas chemistries such as CO/NH3 or CO2/NH3. There is a small chemical contribution to the etch mechanism (i.e. formation of metal carbonyls) as determined by a comparison with Ar and N2 physical sputtering. The discharge should be NH3

  3. Optical theorem and multipole scattering of light by arbitrarily shaped nanoparticles

    NASA Astrophysics Data System (ADS)

    Evlyukhin, Andrey B.; Fischer, Tim; Reinhardt, Carsten; Chichkov, Boris N.

    2016-11-01

    The application of Cartesian multipoles in irreducible representations provides the possibility to get explicit contributions of the toroidal multipole terms in the extinction and scattering power without the introduction of special form factors. In the framework of the Cartesian multipoles, we obtained multipole decomposition (up to the third order) of the induced polarization (current) inside an arbitrarily shaped scatterer (nanoparticle). The third-order decomposition includes the toroidal dipole, magnetic quadrupole, electric octupole terms, and also nonradiating terms. The corresponding multipole decomposition of the scattering cross section, taking into account the electric octupole term, is derived and compared with the multipole decomposition of the extinction cross section obtained using the optical theorem. We show that the role of multipoles in the optical theorem (light extinction) and scattering by arbitrarily shaped nanoparticles can be different. This can result in seemingly paradoxical conclusions with respect to the appearance of multipole contributions in the scattering and extinction cross sections. This fact is especially important for absorptionless nanoparticles, for which the scattering cross section can be calculated using the optical theorem, because in this case extinction is solely determined by scattering. Demonstrative results concerning the role of third-order multipoles in the resonant optical response of high-refractive-index dielectric nanodisks, with and without a through hole at the center, are presented. It is shown that the optical theorem results in a negligible role of the third-order multipoles in the extinction cross sections, whereas these multipoles provide the main contribution in the scattering cross sections.

  4. Laboratory study of avalanches in magnetized plasmas.

    PubMed

    Van Compernolle, B; Morales, G J; Maggs, J E; Sydora, R D

    2015-03-01

    It is demonstrated that a novel heating configuration applied to a large and cold magnetized plasma allows the study of avalanche phenomena under controlled conditions. Intermittent collapses of the plasma pressure profile, associated with unstable drift-Alfvén waves, exhibit a two-slope power-law spectrum with exponents near -1 at lower frequencies and in the range of -2 to -4 at higher frequencies. A detailed mapping of the spatiotemporal evolution of a single avalanche event is presented.

  5. Electromagnetic wave in a relativistic magnetized plasma

    SciTech Connect

    Krasovitskiy, V. B.

    2009-12-15

    Results are presented from a theoretical investigation of the dispersion properties of a relativistic plasma in which an electromagnetic wave propagates along an external magnetic field. The dielectric tensor in integral form is simplified by separating its imaginary and real parts. A dispersion relation for an electromagnetic wave is obtained that makes it possible to analyze the dispersion and collisionless damping of electromagnetic perturbations over a broad parameter range for both nonrelativistic and ultrarelativistic plasmas.

  6. Exact solutions to magnetized plasma flow

    SciTech Connect

    Wang, Zhehui; Barnes, Cris W.

    2001-03-01

    Exact analytic solutions for steady-state magnetized plasma flow (MPF) using ideal magnetohydrodynamics formalism are presented. Several cases are considered. When plasma flow is included, a finite plasma pressure gradient {nabla}p can be maintained in a force-free state JxB=0 by the velocity gradient. Both incompressible and compressible MPF examples are discussed for a Taylor-state spheromak B field. A new magnetized nozzle solution is given for compressible plasma when U{parallel}B. Transition from a magnetized nozzle to a magnetic nozzle is possible when the B field is strong enough. No physical nozzle would be needed in the magnetic nozzle case. Diverging-, drum- and nozzle-shaped MPF solutions when U{perpendicular}B are also given. The electric field is needed to balance the UxB term in Ohm's law. The electric field can be generated in the laboratory with the proposed conducting electrodes. If such electric fields also exist in stars and galaxies, such as through a dynamo process, then these solutions can be candidates to explain single and double jets.

  7. Scaling laws in magnetized plasma turbulence

    SciTech Connect

    Boldyrev, Stanislav

    2015-06-28

    Interactions of plasma motion with magnetic fields occur in nature and in the laboratory in an impressively broad range of scales, from megaparsecs in astrophysical systems to centimeters in fusion devices. The fact that such an enormous array of phenomena can be effectively studied lies in the existence of fundamental scaling laws in plasma turbulence, which allow one to scale the results of analytic and numerical modeling to the sized of galaxies, velocities of supernovae explosions, or magnetic fields in fusion devices. Magnetohydrodynamics (MHD) provides the simplest framework for describing magnetic plasma turbulence. Recently, a number of new features of MHD turbulence have been discovered and an impressive array of thought-provoking phenomenological theories have been put forward. However, these theories have conflicting predictions, and the currently available numerical simulations are not able to resolve the contradictions. MHD turbulence exhibits a variety of regimes unusual in regular hydrodynamic turbulence. Depending on the strength of the guide magnetic field it can be dominated by weakly interacting Alfv\\'en waves or strongly interacting wave packets. At small scales such turbulence is locally anisotropic and imbalanced (cross-helical). In a stark contrast with hydrodynamic turbulence, which tends to ``forget'' global constrains and become uniform and isotropic at small scales, MHD turbulence becomes progressively more anisotropic and unbalanced at small scales. Magnetic field plays a fundamental role in turbulent dynamics. Even when such a field is not imposed by external sources, it is self-consistently generated by the magnetic dynamo action. This project aims at a comprehensive study of universal regimes of magnetic plasma turbulence, combining the modern analytic approaches with the state of the art numerical simulations. The proposed study focuses on the three topics: weak MHD turbulence, which is relevant for laboratory devices, the solar

  8. Plasma observations at the earth's magnetic equator

    NASA Technical Reports Server (NTRS)

    Olsen, R. C.; Shawhan, S. D.; Gallagher, D. L.; Chappell, C. R.; Green, J. L.

    1987-01-01

    New observations of particle and wave data from the magnetic equator from the DE 1 spacecraft are reported. The results demonstrate that the equatorial plasma population is predominantly hydrogen and that the enhanced ion fluxes observed at the equator occur without an increase in the total plasma density. Helium is occasionally found heated along with the protons, and forms about 10 percent of the equatorially trapped population at such times. The heated H(+) ions can be characterized by a bi-Maxwellian with kT(parallel) = 0.5-1.0 eV and kT = 5-50 eV, with a density of 10-100/cu cm. The total plasma density is relatively constant with latitude. First measurements of the equatorially trapped plasma and coincident UHR measurements show that the trapped plasma is found in conjunction with equatorial noise.

  9. Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Cassibry, Jason; Eskridge, Richard; Kirkpatrick, Ronald C.; Knapp, Charles E.; Lee, Michael; Martin, Adam; Smith, James; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    For practical applications of magnetized target fusion, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Quasi-spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a quasi-spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC). Theoretical analysis and computer modeling of the concept are presented. It is shown that, with the appropriate choice of the flow parameters in the liner and the target, the impact between the liner and the target plasma can be made to be shockless in the liner or to generate at most a very weak shock in the liner. Additional information is contained in the original extended abstract.

  10. Stirring a slightly magnetized column of plasma

    NASA Astrophysics Data System (ADS)

    Désangles, Victor; Bousselin, Guillaume; Poyé, Alexandre; Moulin, Marc; de Poucques, Ludovic; Plihon, Nicolas; Physique statistique, Hydrodynamique, Non-Linéarités Team; Département Chimie et Physique des Solides et des Surfaces Team

    2016-10-01

    The von-Kàrmàn plasma experiment (VKP) is a cylindrical, low pressure, high density plasma experiment which confines the plasma thanks to an axial magnetic field. Currents are radially driven between a hot emissive cathode and an anode which apply a Lorentz force on the plasma together with the magnetic field. We demonstrate that current driven radially sets the plasma into rotation. LIF technique at 668.43 nm as well as Mach probes measurements have been developed and used in different regimes in order to measure the velocity of plasma and relate it to the current driven between the electrodes. The LIF signal shows an important widening which corresponds to doppler shift effect due to the velocity of the ions. This widening can be related to the Mach probes signals. In the long term views, each end of the plasma column will be rotating in an opposite direction, such as to create a large shear-layer, resulting in a von-Kàrmàn-type flow.

  11. Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Kirkpatrick, Ronald C.; Knapp, Charles E.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Magnetized target fusion is an emerging, relatively unexplored approach to fusion for electrical power and propulsion application. The physical principles of the concept are founded upon both inertial confinement fusion (ICF) and magnetic confinement fusion (MCF). It attempts to combine the favorable attributes of both these orthogonal approaches to fusion, but at the same time, avoiding the extreme technical challenges of both by exploiting a fusion regime intermediate between them. It uses a material liner to compress, heat and contain the fusion reacting plasma (the target plasma) mentally. By doing so, the fusion burn could be made to occur at plasma densities as high as six orders of magnitude higher than conventional MCF such as tokamak, thus leading to an approximately three orders of magnitude reduction in the plasma energy required for ignition. It also uses a transient magnetic field, compressed to extremely high intensity (100's T to 1000T) in the target plasma, to slow down the heat transport to the liner and to increase the energy deposition of charged-particle fusion products. This has several compounding beneficial effects. It leads to longer energy confinement time compared with conventional ICF without magnetized target, and thus permits the use of much lower plasma density to produce reasonable burn-up fraction. The compounding effects of lower plasma density and the magneto-insulation of the target lead to greatly reduced compressional heating power on the target. The increased energy deposition rate of charged-particle fusion products also helps to lower the energy threshold required for ignition and increasing the burn-up fraction. The reduction in ignition energy and the compressional power compound to lead to reduced system size, mass and R&D cost. It is a fusion approach that has an affordable R&D pathway, and appears attractive for propulsion application in the nearer term.

  12. Gradient expansion, curvature perturbations, and magnetized plasmas

    SciTech Connect

    Giovannini, Massimo; Rezaei, Zahra

    2011-04-15

    The properties of magnetized plasmas are always investigated under the hypothesis that the relativistic inhomogeneities stemming from the fluid sources and from the geometry itself are sufficiently small to allow for a perturbative description prior to photon decoupling. The latter assumption is hereby relaxed and predecoupling plasmas are described within a suitable expansion where the inhomogeneities are treated to a given order in the spatial gradients. It is argued that the (general relativistic) gradient expansion shares the same features of the drift approximation, customarily employed in the description of cold plasmas, so that the two schemes are physically complementary in the large-scale limit and for the low-frequency branch of the spectrum of plasma modes. The two-fluid description, as well as the magnetohydrodynamical reduction, is derived and studied in the presence of the spatial gradients of the geometry. Various solutions of the coupled system of evolution equations in the anti-Newtonian regime and in the quasi-isotropic approximation are presented. The relation of this analysis to the so-called separate universe paradigm is outlined. The evolution of the magnetized curvature perturbations in the nonlinear regime is addressed for the magnetized adiabatic mode in the plasma frame.

  13. Relativistic laser pulse compression in magnetized plasmas

    SciTech Connect

    Liang, Yun; Sang, Hai-Bo Wan, Feng; Lv, Chong; Xie, Bai-Song

    2015-07-15

    The self-compression of a weak relativistic Gaussian laser pulse propagating in a magnetized plasma is investigated. The nonlinear Schrödinger equation, which describes the laser pulse amplitude evolution, is deduced and solved numerically. The pulse compression is observed in the cases of both left- and right-hand circular polarized lasers. It is found that the compressed velocity is increased for the left-hand circular polarized laser fields, while decreased for the right-hand ones, which is reinforced as the enhancement of the external magnetic field. We find a 100 fs left-hand circular polarized laser pulse is compressed in a magnetized (1757 T) plasma medium by more than ten times. The results in this paper indicate the possibility of generating particularly intense and short pulses.

  14. ON THE THEORY OF POLARIZATION TRANSFER IN INHOMOGENEOUS MAGNETIZED PLASMAS,

    DTIC Science & Technology

    PLASMA MEDIUM, ELECTROMAGNETIC RADIATION ), (* ELECTROMAGNETIC RADIATION , POLARIZATION), TRANSFER FUNCTIONS, ASTROPHYSICS, WAVE FUNCTIONS, MAGNETIC FIELDS, MAGNETOOPTICS, PHASE SHIFT CIRCUITS, DIFFERENTIAL EQUATIONS

  15. Magnetized Plasma Compression for Fusion Energy

    NASA Astrophysics Data System (ADS)

    Degnan, James; Grabowski, Christopher; Domonkos, Matthew; Amdahl, David

    2013-10-01

    Magnetized Plasma Compression (MPC) uses magnetic inhibition of thermal conduction and enhancement of charge particle product capture to greatly reduce the temporal and spatial compression required relative to un-magnetized inertial fusion (IFE)--to microseconds, centimeters vs nanoseconds, sub-millimeter. MPC greatly reduces the required confinement time relative to MFE--to microseconds vs minutes. Proof of principle can be demonstrated or refuted using high current pulsed power driven compression of magnetized plasmas using magnetic pressure driven implosions of metal shells, known as imploding liners. This can be done at a cost of a few tens of millions of dollars. If demonstrated, it becomes worthwhile to develop repetitive implosion drivers. One approach is to use arrays of heavy ion beams for energy production, though with much less temporal and spatial compression than that envisioned for un-magnetized IFE, with larger compression targets, and with much less ambitious compression ratios. A less expensive, repetitive pulsed power driver, if feasible, would require engineering development for transient, rapidly replaceable transmission lines such as envisioned by Sandia National Laboratories. Supported by DOE-OFES.

  16. Dynamics of Magnetized Plasma Jets and Bubbles Launched into a Background Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Wallace, B.; Zhang, Y.; Fisher, D. M.; Gilmore, M.

    2016-10-01

    The propagation of dense magnetized plasma, either collimated with mainly azimuthal B-field (jet) or toroidal with closed B-field (bubble), in a background plasma occurs in a number of solar and astrophysical cases. Such cases include coronal mass ejections moving in the background solar wind and extragalactic radio lobes expanding into the extragalactic medium. Understanding the detailed MHD behavior is crucial for correctly modeling these events. In order to further the understanding of such systems, we are investigating the injection of dense magnetized jets and bubbles into a lower density background magnetized plasma using a coaxial plasma gun and a background helicon or cathode plasma. In both jet and bubble cases, the MHD dynamics are found to be very different when launched into background plasma or magnetic field, as compared to vacuum. In the jet case, it is found that the inherent kink instability is stabilized by velocity shear developed due to added magnetic tension from the background field. In the bubble case, rather than directly relaxing to a minimum energy Taylor state (spheromak) as in vacuum, there is an expansion asymmetry and the bubble becomes Rayleigh-Taylor unstable on one side. Recent results will be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  17. Multipole interference in the second-harmonic optical radiation from gold nanoparticles.

    PubMed

    Kujala, Sami; Canfield, Brian K; Kauranen, Martti; Svirko, Yuri; Turunen, Jari

    2007-04-20

    We provide experimental evidence of higher multipole (magnetic dipole and electric quadrupole) radiation in second-harmonic (SH) generation from arrays of metal nanoparticles. Fundamental differences in the radiative properties of electric dipoles and higher multipoles yield opposite interference effects observed in the SH intensities measured in the reflected and transmitted directions. These interference effects clearly depend on the polarization of the fundamental field, directly indicating the importance of multipole effects in the nonlinear response. We estimate that higher multipoles contribute up to 20% of the total emitted SH field amplitude for certain polarization configurations.

  18. Laser plasma in a magnetic field

    SciTech Connect

    Kondo,K.; Kanesue, T.; Tamura, J.; Dabrowski, R.; Okamura, M.

    2009-09-20

    Laser Ion Source (LIS) is a candidate among various heavy ion sources. A high density plasma produced by Nd:YAG laser with drift velocity realizes high current and high charge state ion beams. In order to obtain higher charged particle ions, we had test experiments of LIS with a magnetic field by which a connement effect can make higher charged beams. We measured total current by Faraday Cup (FC) and analyzed charge distribution by Electrostatic Ion Analyzer (EIA). It is shown that the ion beam charge state is higher by a permanent magnet.

  19. Molecular dynamics simulations of magnetized dusty plasmas

    NASA Astrophysics Data System (ADS)

    Piel, Alexander; Reichstein, Torben; Wilms, Jochen

    2012-10-01

    The combination of the electric field that confines a dust cloud with a static magnetic field generally leads to a rotation of the dust cloud. In weak magnetic fields, the Hall component of the ion flow exerts a drag force that sets the dust in rotation. We have performed detailed molecular-dynamics simulations of the dynamics of torus-shaped dust clouds in anodic plasmas. The stationary flow [1] is characterized by a shell structure in the laminar dust flow and by the spontaneous formation of a shear-flow around a stationary vortex. Here we present new results on dynamic phenomena, among them fluctuations due to a Kelvin-Helmholtz instability in the shear-flow. The simulations are compared with experimental results. [4pt] [1] T. Reichstein, A. Piel, Phys. Plasmas 18, 083705 (2011)

  20. Plasma networking in magnetically confined plasmas and diagnostics of nonlocal heat transport in tokamak filamentary plasmas

    NASA Astrophysics Data System (ADS)

    Kukushkin, A. B.; Rantsev-Kartinov, V. A.

    1999-02-01

    The method of multilevel dynamical contrasting is applied to analyzing available data from tokamak plasmas. The results illustrate a possibility of extending the concept of the plasma percolating networks in dense Z pinches (and other inertially confined plasmas) to the case of magnetically confined plasmas. This extension suggests a necessity to append the conventional picture of the nonfilamentary plasma (which is nearly a fluid described by conventional magnetohydrodynamics) with a "network" component which is formed by the strongest long-living filaments of electric current and penetrate the "fluid" component. Signs of networking are found in visible light and soft x-ray images, and magnetic probing data. A diagnostic algorithm is formulated for identifying the role of plasma networking in observed phenomena of nonlocal (non-diffusive) heat transport in a tokamak.

  1. Plasma Detachment Mechanisms in Propulsive Magnetic Nozzles

    DTIC Science & Technology

    2013-03-07

    a marginal fraction of the beam flows back and the divergence angle of the 95%-mass tube measures the effectiveness of detachment, allowing...propellants1,15; and high throttlability, based on the capability of actuating, at constant power, on both the gas flow and the magnetic nozzle16. However...unlimited. Thus, central to our model will be to include the 2D depletion of the injected gas flow , which is governed by the competition between plasma

  2. Magnetic surface topology in decaying plasma knots

    NASA Astrophysics Data System (ADS)

    Smiet, C. B.; Thompson, A.; Bouwmeester, P.; Bouwmeester, D.

    2017-02-01

    Torus-knot solitons have recently been formulated as solutions to the ideal incompressible magnetohydrodynamics (MHD) equations. We investigate numerically how these fields evolve in resistive, compressible, and viscous MHD. We find that certain decaying plasma torus knots exhibit magnetic surfaces that are topologically distinct from a torus. The evolution is predominantly determined by a persistent zero line in the field present when the poloidal winding number {n}{{p}}\

  3. Magnetic reconnection in a weakly ionized plasma

    SciTech Connect

    Leake, James E.; Lukin, Vyacheslav S.; Linton, Mark G.

    2013-06-15

    Magnetic reconnection in partially ionized plasmas is a ubiquitous phenomenon spanning the range from laboratory to intergalactic scales, yet it remains poorly understood and relatively little studied. Here, we present results from a self-consistent multi-fluid simulation of magnetic reconnection in a weakly ionized reacting plasma with a particular focus on the parameter regime of the solar chromosphere. The numerical model includes collisional transport, interaction and reactions between the species, and optically thin radiative losses. This model improves upon our previous work in Leake et al.[“Multi-fluid simulations of chromospheric magnetic reconnection in a weakly ionized reacting plasma,” Astrophys. J. 760, 109 (2012)] by considering realistic chromospheric transport coefficients, and by solving a generalized Ohm's law that accounts for finite ion-inertia and electron-neutral drag. We find that during the two dimensional reconnection of a Harris current sheet with an initial width larger than the neutral-ion collisional coupling scale, the current sheet thins until its width becomes less than this coupling scale, and the neutral and ion fluids decouple upstream from the reconnection site. During this process of decoupling, we observe reconnection faster than the single-fluid Sweet-Parker prediction, with recombination and plasma outflow both playing a role in determining the reconnection rate. As the current sheet thins further and elongates, it becomes unstable to the secondary tearing instability, and plasmoids are seen. The reconnection rate, outflows, and plasmoids observed in this simulation provide evidence that magnetic reconnection in the chromosphere could be responsible for jet-like transient phenomena such as spicules and chromospheric jets.

  4. Plasma-induced magnetic responses during nonlinear dynamics of magnetic islands due to resonant magnetic perturbations

    SciTech Connect

    Nishimura, Seiya

    2014-12-15

    Resonant magnetic perturbations (RMPs) produce magnetic islands in toroidal plasmas. Self-healing (annihilation) of RMP-induced magnetic islands has been observed in helical systems, where a possible mechanism of the self-healing is shielding of RMP penetration by plasma flows, which is well known in tokamaks. Thus, fundamental physics of RMP shielding is commonly investigated in both tokamaks and helical systems. In order to check this mechanism, detailed informations of magnetic island phases are necessary. In experiments, measurement of radial magnetic responses is relatively easy. In this study, based on a theoretical model of rotating magnetic islands, behavior of radial magnetic fields during the self-healing is investigated. It is confirmed that flips of radial magnetic fields are typically observed during the self-healing. Such behavior of radial magnetic responses is also observed in LHD experiments.

  5. Novel multipole Wien filter as three-dimensional spin manipulator

    SciTech Connect

    Yasue, T. Suzuki, M.; Koshikawa, T.; Tsuno, K.; Goto, S.; Arai, Y.

    2014-04-15

    Spin polarized electron beam is often used in material characterizations which relates to magnetism as well as in the high energy particle physics. The manipulation of the spin polarization toward the arbitrary direction is indispensable in such studies. In the present work, a novel multipole Wien filter is proposed as the three-dimensional spin manipulator, and a prototype 8-pole Wien filter is developed. It is applied to spin polarized low energy electron microscopy, and the variation of the magnetic contrast with managing the spin polarization is evaluated. It is confirmed that the novel multipole Wien filter can manipulate the spin polarization three-dimensionally.

  6. Plasma Braking Due to External Magnetic Perturbations

    NASA Astrophysics Data System (ADS)

    Frassinetti, L.; Olofsson, Kejo; Brunsell, P. R.; Khan, M. W. M.; Drake, J. R.

    2010-11-01

    The RFP EXTRAP T2R is equipped with a comprehensive active feedback system (128 active saddle coils in the full-coverage array) and active control of both resonant and non-resonant MHD modes has been demonstrated. The feedback algorithms, based on modern control methodology such as reference mode tracking (both amplitude and phase), are a useful tool to improve the ``state of the art'' of the MHD mode control. But this tool can be used also to improve the understanding and the characterization of other phenomena such as the ELM mitigation with a resonant magnetic perturbation or the plasma viscosity. The present work studies plasma and mode braking due to static RMPs. Results show that a static RMP produces a global braking of the flow profile. The study of the effect of RMPs characterized by different helicities will also give information on the plasma viscosity profile. Experimental results are finally compared to theoretical models.

  7. Forced magnetic reconnection in Tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Cole, Andrew Joseph

    This dissertation addresses two related problems in the study of forced magnetic reconnection in Tokamak plasmas. First, a recent controversy concerning a model forced magnetic reconnection problem, the Taylor problem, has been resolved. The criticisms of Ishizawa and Tokuda [21] concerning the original analysis of Hahm and Kulsrud [17] are shown to be unwarranted, both analytically and numerically. Second, one possible reason for the discrepancy between recent experimental [29] and previous theoretical [13] scaling of the critical error-field penetration threshold with device parameters is addressed. The theory in question is entirely based on a single-fluid MHD (magnetohydrodynamical) treatment of the plasma. As is well-known, high temperature plasmas are far better modeled using the drift-MHD ordering.[18] Hence we develop a drift-MHD theory of error-field penetration. Although two new drift-MHD plasma response regimes are identified, the overall threshold scaling with device parameters is not altogether different from that predicted by single-fluid MHD.

  8. Proton acceleration from magnetized overdense plasmas

    NASA Astrophysics Data System (ADS)

    Kuri, Deep Kumar; Das, Nilakshi; Patel, Kartik

    2017-01-01

    Proton acceleration by an ultraintense short pulse circularly polarized laser from an overdense three dimensional (3D) particle-in-cell (PIC) 3D-PIC simulations. The axial magnetic field modifies the dielectric constant of the plasma, which causes a difference in the behaviour of ponderomotive force in case of left and right circularly polarized laser pulse. When the laser is right circularly polarized, the ponderomotive force gets enhanced due to cyclotron effects generating high energetic electrons, which, on reaching the target rear side accelerates the protons via target normal sheath acceleration process. On the other hand, in case of left circular polarization, the effects get reversed causing a suppression of the ponderomotive force at a short distance and lead towards a rise in the radiation pressure, which results in the effective formation of laser piston. Thus, the axial magnetic field enhances the effect of radiation pressure in case of left circularly polarized laser resulting in the generation of high energetic protons at the target front side. The transverse motion of protons get reduced as they gyrate around the axial magnetic field which increases the beam collimation to some extent. The optimum thickness of the overdense plasma target is found to be increased in the presence of an axial magnetic field.

  9. Dust particle dynamics in magnetized plasma sheath

    SciTech Connect

    Davoudabadi, M.; Mashayek, F.

    2005-07-15

    In this paper, the structure of a plasma sheath in the presence of an oblique magnetic field is investigated, and dynamics of a dust particle embedded in the sheath is elaborated. To simulate the sheath, a weakly collisional two-fluid model is implemented. For various magnitudes and directions of the magnetic field and chamber pressures, different plasma parameters including the electron and ion densities, ion flow velocity, and electric potential are calculated. A complete set of forces acting on the dust particle originating from the electric field in the sheath, the static magnetic field, gravity, and ion and neutral drags is taken into account. Through the trapping potential energy, the particle stable and unstable equilibria are studied while the particle is stationary inside the sheath. Other features such as the possibility of the dust levitation and trapping in the sheath, and the effect of the Lorentz force on the charged dust particle motion are also examined. An interesting feature is captured for the variation of the particle charge as a function of the magnetic field magnitude.

  10. NEUTRON SOURCE USING MAGNETIC COMPRESSION OF PLASMA

    DOEpatents

    Quinn, W.E.; Elmore, W.C.; Little, E.M.; Boyer, K.; Tuck, J.L.

    1961-10-31

    A fusion reactor is described that utilizes compression and heating of an ionized thermonuclear fuel by an externally applied magnetic field, thus avoiding reliance on the pinch effect and its associated instability problems. The device consists of a gas-confining ceramic container surrounded by a single circumferential coil having a shape such as to produce a magnetic mirror geometry. A sinusoidally-oscillating, exponentially-damped current is passed circumferentially around the container, through the coil, inducing a circumferential current in the gas. Maximum compression and plasma temperature are obtained at the peak of the current oscillations, coinciding with maximum magnetic field intensity. Enhanced temperatures are obtained in the second and succeeding half cycles because the thermal energy accumulates from one half cycle to the next. (AEC)

  11. Modulation instability of laser pulse in magnetized plasma

    SciTech Connect

    Jha, Pallavi; Kumar, Punit; Raj, Gaurav; Upadhyaya, Ajay K.

    2005-12-15

    Modulation instability of a laser pulse propagating through transversely magnetized underdense plasma is studied. It is observed that interaction of laser radiation with plasma in the presence of uniform magnetic field results in an additional perturbed transverse plasma current density along with the relativistic and ponderomotive nonlinear current densities, thus affecting the modulational interaction. In the plane wave limit it is observed that modulational interaction is more stable for magnetized plasma as compared to the unmagnetized case. The analysis shows that there is a significant reduction in the growth rate of modulation instability over a given range of unstable wave numbers due to magnetization of plasma.

  12. Axisymmetric plasma equilibrium in gravitational and magnetic fields

    SciTech Connect

    Krasheninnikov, S. I.; Catto, P. J.

    2015-12-15

    Plasma equilibria in gravitational and open-ended magnetic fields are considered for the case of topologically disconnected regions of the magnetic flux surfaces where plasma occupies just one of these regions. Special dependences of the plasma temperature and density on the magnetic flux are used which allow the solution of the Grad–Shafranov equation in a separable form permitting analytic treatment. It is found that plasma pressure tends to play the dominant role in the setting the shape of magnetic field equilibrium, while a strong gravitational force localizes the plasma density to a thin disc centered at the equatorial plane.

  13. Axisymmetric plasma equilibrium in gravitational and magnetic fields

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, S. I.; Catto, P. J.

    2015-12-01

    Plasma equilibria in gravitational and open-ended magnetic fields are considered for the case of topologically disconnected regions of the magnetic flux surfaces where plasma occupies just one of these regions. Special dependences of the plasma temperature and density on the magnetic flux are used which allow the solution of the Grad-Shafranov equation in a separable form permitting analytic treatment. It is found that plasma pressure tends to play the dominant role in the setting the shape of magnetic field equilibrium, while a strong gravitational force localizes the plasma density to a thin disc centered at the equatorial plane.

  14. Collisionless Magnetic Reconnection in Space Plasmas

    NASA Astrophysics Data System (ADS)

    Treumann, Rudolf A.; Baumjohann, Wolfgang

    2013-12-01

    Magnetic reconnection, the merging of oppositely directed magnetic fields that leads to field reconfiguration, plasma heating, jetting and acceleration, is one of the most celebrated processes in collisionless plasmas. It requires the violation of the frozen-in condition which ties gyrating charged particles to the magnetic field inhibiting diffusion. Ongoing reconnection has been identified in near-Earth space as being responsible for the excitation of substorms, magnetic storms, generation of field aligned currents and their consequences, the wealth of auroral phenomena. Its theoretical understanding is now on the verge of being completed. Reconnection takes place in thin current sheets. Analytical concepts proceeded gradually down to the microscopic scale, the scale of the electron skin depth or inertial length, recognizing that current layers that thin do preferentially undergo spontaneous reconnection. Thick current layers start reconnecting when being forced by plasma inflow to thin. For almost half a century the physical mechanism of reconnection has remained a mystery. Spacecraft in situ observations in combination with sophisticated numerical simulations in two and three dimensions recently clarified the mist, finding that reconnection produces a specific structure of the current layer inside the electron inertial (also called electron diffusion) region around the reconnection site, the X line. Onset of reconnection is attributed to pseudo-viscous contributions of the electron pressure tensor aided by electron inertia and drag, creating a complicated structured electron current sheet, electric fields, and an electron exhaust extended along the current layer. We review the general background theory and recent developments in numerical simulation on collisionless reconnection. It is impossible to cover the entire field of reconnection in a short space-limited review. The presentation necessarily remains cursory, determined by our taste, preferences, and kn

  15. Low-frequency fluctuations in plasma magnetic fields

    NASA Astrophysics Data System (ADS)

    Cable, S.; Tajima, T.

    1992-02-01

    It is shown that even a non-magnetized plasma with temperature T sustains zero-frequency magnetic fluctuations in thermal equilibrium. Fluctuations in electric and magnetic fields, as well as in densities, are computed. Four cases are studied: a cold, gaseous, isotropic, non-magnetized plasma; a cold, gaseous plasma in a uniform magnetic field; a warm, gaseous plasma described by kinetic theory; and a degenerate electron plasma. For the simple gaseous plasma, the fluctuation strength of the magnetic field as a function of frequency and wavenumber is calculated with the aid of the fluctuation-dissipation theorem. This calculation is done for both collisional and collisionless plasmas. The magnetic field fluctuation spectrum of each plasma has a large zero-frequency peak. The peak is a Dirac delta function in the collisionless plasma and is broadened into a Lorentzian curve in the collisional plasma. The plasma causes a low frequency cutoff in the typical black-body radiation spectrum, and the energy under the discovered peak approximates the energy lost in this cutoff. When the imposed magnetic field is weak, the magnetic field wave vector fluctuation spectra of the two lowest modes are independent of the strength of the imposed field. Further, these modes contain finite energy even when the imposed field is zero. It is the energy of these modes which forms the non-magnetized zero-frequency peak of the isotropic plasma. In deriving these results, a simple relationship between the dispersion relation and the fluctuation power spectrum of electromagnetic waves if found. The warm plasma is shown, by kinetic theory, to exhibit a zero-frequency peak in its magnetic field fluctuation spectrum as well. For the degenerate plasma, we find that electric field fluctuations and number density fluctuations vanish at zero frequency; however, the magnetic field power spectrum diverges at zero frequency.

  16. Experimental investigation of plasma relaxation using a compact coaxial magnetized plasma gun in a background plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott; University of New Mexico Collaboration; Los Alamos National Laboratory Collaboration

    2013-10-01

    A compact coaxial plasma gun is employed for experimental studies of plasma relaxation in a low density background plasma. Experiments are being conducted in the linear HelCat device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes within the intergalactic medium. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5-10 kV and ~100 kA. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities ~1.2Cs and densities ~1020 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

  17. Generation of quasistationary magnetic fields in a turbulent laser plasma

    NASA Astrophysics Data System (ADS)

    Bychenkov, V. Iu.; Gradov, O. M.; Chokparova, G. A.

    1984-07-01

    A theory is derived for the generation of quasi-stationary magnetic fields in a laser plasma with well developed ion-acoustic turbulence. Qualitative changes are caused in the nature of the magnetic-field generation by an anomalous anisotropic transport in the turbulent plasma. The role played by turbulent diffusion and thermodiffusive transport in the magnetic-field saturation is discussed.

  18. Plasma sweeper to control the coupling of RF power to a magnetically confined plasma

    DOEpatents

    Motley, Robert W.; Glanz, James

    1985-01-01

    A device for coupling RF power (a plasma sweeper) from a phased waveguide array for introducing RF power to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the phased waveguide array; and a potential source coupled to the electrode for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  19. Intense Magnetized Plasma-Wall Interaction

    SciTech Connect

    Bauer, Bruno S.; Fuelling, Stephan

    2013-11-30

    This research project studied wall-plasma interactions relevant to fusion science. Such interactions are a critical aspect of Magneto-Inertial Fusion (MIF) because flux compression by a pusher material, in particular the metal for the liner approach to MIF, involves strong eddy current heating on the surface of the pusher, and probably interactions and mixing of the pusher with the interior fuel during the time when fusion fuel is being burned. When the pusher material is a metal liner, high-energy-density conditions result in fascinating behavior. For example, "warm dense matter" is produced, for which material properties such as resistivity and opacity are not well known. In this project, the transformation into plasma of metal walls subjected to pulsed megagauss magnetic fields was studied with an experiment driven by the UNR 1 MA Zebra generator. The experiment was numerically simulated with using the MHRDR code. This simple, fundamental high-energy-density physics experiment, in a regime appropriate to MIF, has stimulated an important and fascinating comparison of numerical modeling codes and tables with experiment. In addition, we participated in developing the FRCHX experiment to compress a field-reversed-configuration (FRC) plasma with a liner, in collaboration with researchers from Air Force Research Laboratory and Los Alamos National Lab, and we helped develop diagnostics for the Plasma Liner Experiment (PLX) at LANL. Last, but not least, this project served to train students in high-energy-density physics.

  20. Magnetized laboratory plasma jets: experiment and simulation.

    PubMed

    Schrafel, Peter; Bell, Kate; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-01-01

    Experiments involving radial foils on a 1 MA, 100 ns current driver can be used to study the ablation of thin foils and liners, produce extreme conditions relevant to laboratory astrophysics, and aid in computational code validation. This research focuses on the initial ablation phase of a 20 μm Al foil (8111 alloy), in a radial configuration, driven by Cornell University's COBRA pulsed power generator. In these experiments ablated surface plasma (ASP) on the top side of the foil and a strongly collimated axial plasma jet are observed developing midway through the current rise. With experimental and computational results this work gives a detailed description of the role of the ASP in the formation of the plasma jet with and without an applied axial magnetic field. This ∼1 T field is applied by a Helmholtz-coil pair driven by a slow, 150 μs current pulse and penetrates the load hardware before arrival of the COBRA pulse. Several effects of the applied magnetic field are observed: (1) without the field extreme-ultraviolet emission from the ASP shows considerable azimuthal asymmetry while with the field the ASP develops azimuthal motion that reduces this asymmetry, (2) this azimuthal motion slows the development of the jet when the field is applied, and (3) with the magnetic field the jet becomes less collimated and has a density minimum (hollowing) on the axis. PERSEUS, an XMHD code, has qualitatively and quantitatively reproduced all these experimental observations. The differences between this XMHD and an MHD code without a Hall current and inertial effects are discussed. In addition the PERSEUS results describe effects we were not able to resolve experimentally and suggest a line of future experiments with better diagnostics.

  1. Three-dimensional model of magnetized capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid; Kenney, Jason; Collins, Ken

    2009-05-01

    A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O2) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the E ×B drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the E ×B drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the E ×B drift. The E ×B drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the E ×B drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O2 plasma, the overall plasma is found to move in one direction due to the E ×B drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the E ×B drift direction.

  2. Simulating Coulomb collisions in a magnetized plasma

    SciTech Connect

    Hinton, Fred L.

    2008-04-15

    The problem of simulating ion-ion Coulomb collisions in a plasma in a strong magnetic field is considered. No assumption is made about the ion distribution function except that it is independent of the gyrophase angle, consistent with the assumption that the ion gyrofrequency is much larger than the ion-ion collision frequency. A Langevin method is presented which time-advances the components of a particle's velocity parallel and perpendicular to the magnetic field, without following the rapidly changing gyrophase. Although the standard Monte Carlo procedure, which uses random sampling, can be used, it is also possible to use a deterministic sampling procedure, where the samples are determined by the points which would be used in a numerical quadrature formula for moments of the Fokker-Planck Green's function. This should reduce the sampling noise compared with the Monte Carlo collision method.

  3. Fast magnetic field penetration into low resistivity plasma

    NASA Astrophysics Data System (ADS)

    Fruchtman, Amnon

    2017-02-01

    Penetration of a magnetic field into plasma that is faster than resistive diffusion can be induced by the Hall electric field in a non-uniform plasma. This mechanism explained successfully the measured velocity of the magnetic field penetration into pulsed plasmas. Major related issues have not yet been resolved. Such is the theoretically predicted, but so far not verified experimentally, high magnetic energy dissipation, as well as the correlation between the directions of the density gradient and of the field penetration.

  4. Turbulent particle transport in magnetized fusion plasma

    NASA Astrophysics Data System (ADS)

    Bourdelle, C.

    2005-05-01

    Understanding the mechanisms responsible for particle transport is of the utmost importance for magnetized fusion plasmas. A peaked density profile is attractive to improve the fusion rate, which is proportional to the square of the density, and to self-generate a large fraction of non-inductive current required for continuous operation. Experiments in various tokamak devices (ASDEX Upgrade, DIII-D, JET, TCV, TEXT, TFTR) indicate the existence of a turbulent particle pinch. Recently, such a turbulent pinch has been unambiguously identified in Tore Supra very long discharges, in the absence of both collisional particle pinch and central particle source, for more than 4 min (Hoang et al 2003 Phys. Rev. Lett. 90 155002). This turbulent pinch is predicted by a quasilinear theory of particle transport (Weiland J et al 1989 Nucl. Fusion 29 1810), and confirmed by non-linear turbulence simulations (Garbet et al 2003 Phys. Rev. Lett. 91 035001) and general considerations based on the conservation of motion invariants (Baker et al 2004 Phys. Plasmas 11 992). Experimentally, the particle pinch is found to be sensitive to the magnetic field gradient in many cases (Hoang et al 2004 Phys. Rev. Lett. 93 135003, Zabolotsky et al 2003 Plasma Phys. Control. Fusion 45 735, Weisen et al 2004 Plasma Phys. Control. Fusion 46 751, Baker et al 2000 Nucl. Fusion 40 1003), to the temperature profile (Hoang et al 2004 Phys. Rev. Lett. 93 135003, Angioni et al 2004 Nucl. Fusion 44 827) and also to the collisionality that changes the nature of the microturbulence (Angioni et al 2003 Phys. Rev. Lett. 90 205003, Garzotti et al 2003 Nucl. Fusion 43 1829, Weisen et al 2004 31st EPS Conf. on Plasma Phys. (London) vol 28G (ECA) P-1.146, Lopes Cardozo N J 1995 Plasma Phys. Control. Fusion 37 799). The consistency of some of the observed dependences with the theoretical predictions gives us a clearer understanding of the particle pinch in tokamaks, allowing us to predict more accurately the density

  5. METHOD FOR EXCHANGING ENERGY WITH A PLASMA BY MAGNETIC PUMPING

    DOEpatents

    Hall, L.S.

    1963-12-31

    A method of heating a plasma confined by a static magnetic field is presented. A time-varying magnetic field having a rise time to a predetermined value substantially less than its fall time is applied to a portion of the plasma. Because of the much shorter rise time, the plasma is reversibly heated. This cycle is repeated until the desired plasma temperature is reached. (AEC)

  6. Penetration of conductive plasma flows across a magnetic field

    NASA Astrophysics Data System (ADS)

    Plechaty, Christopher Ryan

    2008-02-01

    Plasma interacts with magnetic fields in a variety of natural and laboratory settings. While a magnetic field "traps" isolated charged particles, plasma penetration across magnetic field is observed in many situations where a plasma-magnetic interface exists. For example, in the realm of pulsed power technology, this behavior is important for magnetically insulated transmission lines and for plasma opening switches. In the realm of astrophysics, the nature of the interaction between the solar wind plasma and the Earth's magnetic field affects the reliability of telecommunication devices and satellites. Experiments were performed at the Nevada Terawatt Facility to investigate how a conductive plasma penetrates an externally applied magnetic field. In experiment, a plasma flow was produced by laser ablation. This plasma was observed to penetrate an externally applied magnetic field produced by a 0.6 MA pulsed power generator. In experiment, the duration of the laser pulse was changed by three orders of magnitude, from ns (GW pulse power) to ps (TW) . This resulted in a significant variation of the plasma parameters, which in turn led to the actuation of different magnetic field penetration mechanisms.

  7. Magnetized plasma jets in experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Greenly, John; Gourdain, Pierre; Seyler, Charles; Blesener, Kate; Kusse, Bruce

    2013-10-01

    This research focuses on the initial ablation phase of a thing (20 micron) Al foil driven on the 1 MA-in-100 ns COBRA through a 5 mm diameter cathode in a radial configuration. In these experiments, ablated surface plasma (ASP) on the top of the foil and a strongly collimated axial plasma jet can be observed developing midway through current-rise. Our goal is to establish the relationship between the ASP and the jet. These jets are of interest for their potential relevance to astrophysical phenomena. An independently pulsed 200 μF capacitor bank with a Helmholtz coil pair allows for the imposition of a slow (150 μs) and strong (~1 T) axial magnetic field on the experiment. Application of this field eliminates significant azimuthal asymmetry in extreme ultraviolet emission of the ASP. This asymmetry is likely a current filamentation instability. Laser-backlit shadowgraphy and interferometry confirm that the jet-hollowing is correlated with the application of the axial magnetic field. Visible spectroscopic measurements show a doppler shift consistent with an azimuthal velocity in the ASP caused by the applied B-field. Computational simulations with the XMHD code PERSEUS qualitatively agree with the experimental results.

  8. Status of Magnetic Nozzle and Plasma Detachment Experiment

    SciTech Connect

    Chavers, D. Gregory; Dobson, Chris; Jones, Jonathan; Lee, Michael; Martin, Adam; Gregory, Judith; Cecil, Jim; Bengtson, Roger D.; Breizman, Boris; Arefiev, Alexey; Chang-Diaz, Franklin; Squire, Jared; Glover, Tim; McCaskill, Greg; Cassibry, Jason; Li Zhongmin

    2006-01-20

    High power plasma propulsion can move large payloads for orbit transfer, lunar missions, and beyond with large savings in fuel consumption owing to the high specific impulse. At high power, lifetime of the thruster becomes an issue. Electrodeless devices with magnetically guided plasma offer the advantage of long life since magnetic fields confine the plasma radially and keep it from impacting the material surfaces. For decades, concerns have been raised about the plasma remaining attached to the magnetic field and returning to the vehicle along the closed magnetic field lines. Recent analysis suggests that this may not be an issue if the magnetic field is properly shaped in the nozzle region and the plasma has sufficient energy density to stretch the magnetic field downstream. An experiment is being performed to test the theory regarding the MHD detachment scenario. The status of that experiment will be discussed in this paper.

  9. Analysis of magnetic field plasma interactions using microparticles as probes

    NASA Astrophysics Data System (ADS)

    Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin S.; Hyde, Truell W.

    2015-08-01

    The interaction between a magnetic field and plasma close to a nonconductive surface is of interest for both science and technology. In space, crustal magnetic fields on celestial bodies without atmosphere can interact with the solar wind. In advanced technologies such as those used in fusion or spaceflight, magnetic fields can be used to either control a plasma or protect surfaces exposed to the high heat loads produced by plasma. In this paper, a method will be discussed for investigating magnetic field plasma interactions close to a nonconductive surface inside a Gaseous Electronics Conference reference cell employing dust particles as probes. To accomplish this, a magnet covered by a glass plate was exposed to a low power argon plasma. The magnetic field was strong enough to magnetize the electrons, while not directly impacting the dynamics of the ions or the dust particles used for diagnostics. In order to investigate the interaction of the plasma with the magnetic field and the nonconductive surface, micron-sized dust particles were introduced into the plasma and their trajectories were recorded with a high-speed camera. Based on the resulting particle trajectories, the accelerations of the dust particles were determined and acceleration maps over the field of view were generated which are representative of the forces acting on the particles. The results show that the magnetic field is responsible for the development of strong electric fields in the plasma, in both horizontal and vertical directions, leading to complex motion of the dust particles.

  10. The multipole resonance probe: characterization of a prototype

    NASA Astrophysics Data System (ADS)

    Lapke, Martin; Oberrath, Jens; Schulz, Christian; Storch, Robert; Styrnoll, Tim; Zietz, Christian; Awakowicz, Peter; Brinkmann, Ralf Peter; Musch, Thomas; Mussenbrock, Thomas; Rolfes, Ilona

    2011-08-01

    The multipole resonance probe (MRP) was recently proposed as an economical and industry compatible plasma diagnostic device (Lapke et al 2008 Appl. Phys. Lett. 93 051502). This communication reports the experimental characterization of a first MRP prototype in an inductively coupled argon/nitrogen plasma at 10 Pa. The behavior of the device follows the predictions of both an analytical model and a numerical simulation. The obtained electron densities are in excellent agreement with the results of Langmuir probe measurements.

  11. Exact e-e (exchange) correlations of 2-D quantum dots in magnetic field: Size extensive N = 3 , 4 , … , ‧ n ‧ -electron systems via multi-pole expansion

    NASA Astrophysics Data System (ADS)

    Aggarwal, Priyanka; Sharma, Shivalika; Singh, Sunny; Kaur, Harsimran; Hazra, Ram Kuntal

    2017-04-01

    Inclusion of coulomb interaction emerges with the complexity of either convergence of integrals or separation of variables of Schrödinger equations. For an N-electron system, interaction terms grow by N(N-1)/2 factors. Therefore, 2-e system stands as fundamental basic unit for generalized N-e systems. For the first time, we have evaluated e-e correlations in very simple and absolutely terminating finite summed hypergeometric series for 2-D double carrier parabolic quantum dot in both zero and arbitrary non-zero magnetic field (symmetric gauge) and have appraised these integrals in variational methods. The competitive role among confinement strength, magnetic field, mass of the carrier and dielectric constant of the medium on energy level diagram, level-spacing statistics, heat capacities (Cv at 1 K) and magnetization (T ∼ (0-1)K) is studied on systems spanning over wide range of materials (GaAs,Ge,CdS,SiO2 and He, etc). We have also constructed an exact theory for generalized correlated N-e 2-D quantum dots via multi-pole expansion but for the sake of compactness of the article we refrain from data.

  12. Magnetic Cusp Configuration of the SPL Plasma Generator

    SciTech Connect

    Kronberger, Matthias; Chaudet, Elodie; Favre, Gilles; Lettry, Jacques; Kuechler, Detlef; Moyret, Pierre; Paoluzzi, Mauro; Prever-Loiri, Laurent; Schmitzer, Claus; Scrivens, Richard; Steyaert, Didier

    2011-09-26

    The Superconducting Proton Linac (SPL) is a novel linear accelerator concept currently studied at CERN. As part of this study, a new Cs-free, RF-driven external antenna H{sup -} plasma generator has been developed to withstand an average thermal load of 6 kW. The magnetic configuration of the new plasma generator includes a dodecapole cusp field and a filter field separating the plasma heating and H{sup -} production regions. Ferrites surrounding the RF antenna serve in enhancing the coupling of the RF to the plasma. Due to the space requirements of the plasma chamber cooling circuit, the cusp magnets are pushed outwards compared to Linac4 and the cusp field strength in the plasma region is reduced by 40% when N-S magnetized magnets are used. The cusp field strength and plasma confinement can be improved by replacing the N-S magnets with offset Halbach elements of which each consists of three magnetic sub-elements with different magnetization direction. A design challenge is the dissipation of RF power induced by eddy currents in the cusp and filter magnets which may lead to overheating and demagnetization. In view of this, a copper magnet cage has been developed that shields the cusp magnets from the radiation of the RF antenna.

  13. A Guide to Electronic Multipoles in Photon Scattering and Absorption

    NASA Astrophysics Data System (ADS)

    Lovesey, Stephen William; Balcar, Ewald

    2013-02-01

    The practice of replacing matrix elements in atomic calculations by those of convenient operators with strong physical appeal has a long history, and in condensed matter physics it is perhaps best known through use of operator equivalents in electron resonance by Elliott and Stevens. Likewise, electronic multipoles, created with irreducible spherical-tensors, to represent charge-like and magnetic-like quantities are widespread in modern physics. Examples in recent headlines include a magnetic charge (a monopole), an anapole (a dipole) and a triakontadipole (a magnetic-like atomic multipole of rank 5). In this communication, we aim to guide the reader through use of atomic, spherical multipoles in photon scattering, and resonant Bragg diffraction and dichroic signals in particular. Applications to copper oxide CuO and neptunium dioxide (NpO2) are described. In keeping with it being a simple guide, there is sparse use in the communication of algebra and expressions are gathered from the published literature and not derived, even when central to the exposition. An exception is a thorough grounding, contained in an Appendix, for an appropriate version of the photon scattering length based on quantum electrodynamics. A theme of the guide is application of symmetry in scattering, in particular constraints imposed on results by symmetry in crystals. To this end, a second Appendix catalogues constraints on multipoles imposed by symmetry in crystal point-groups.

  14. Axisymmetric global gravitational equilibrium for magnetized, rotating hot plasma

    NASA Astrophysics Data System (ADS)

    Catto, Peter J.; Pusztai, Istvan; Krasheninnikov, Sergei I.

    2015-12-01

    > We present analytic solutions for three-dimensional magnetized axisymmetric equilibria confining rotating hot plasma in a gravitational field. Our up-down symmetric solution to the full Grad-Shafranov equation can exhibit equatorial plane localization of the plasma density and current, resulting in disk equilibria for the plasma density. For very weak magnetic fields and high plasma pressure, we find strongly rotating thin plasma disk gravitational equilibria that satisfy strict Keplerian motion provided the gravitational energy is much larger than the plasma pressure, which must be large compared to the magnetic energy of the poloidal magnetic field. When the rotational energy exceeds the gravitational energy and it is larger than the plasma pressure, diffuse disk equilibrium solutions continue to exist provided the poloidal magnetic energy remains small. For stronger magnetic fields and lower plasma pressure and rotation, we can also find gravitational equilibria with strong localization to the equatorial plane. However, a toroidal magnetic field is almost always necessary to numerically verify these equilibria are valid solutions in the presence of gravity for the cases considered in Catto & Krasheninnikov (J. Plasma Phys., vol. 81, 2015, 105810301). In all cases both analytic and numerical results are presented.

  15. Plasma Transport in a Magnetic Multicusp Negative Hydrogen Ion Source

    DTIC Science & Technology

    1991-12-01

    the Extraction Electrode ............................ 4-4 Analysis of the Effect of Temperature Gradients on the Flux...Measured vs Predicted Ion Species Percentages ......... 5-31 x Abstract An analysis of plasma transport through the magnetic filter in mag- netic...diffusion through the magnetic filter field into the extraction chamber. The goal was not, however, simply to calculate the plasma potential. Analysis of

  16. On the generation of magnetic field enhanced microwave plasma line

    NASA Astrophysics Data System (ADS)

    Chen, Longwei; Zhao, Ying; Wu, Kenan; Wang, Qi; Meng, Yuedong; Ren, Zhaoxing

    2016-12-01

    Microwave linear plasmas sustained by surface waves have attracted much attention due to the potential abilities to generate large-scale and uniform non-equilibrium plasmas. An external magnetic field was generally applied to enhance and stabilize plasma sources because the magnetic field decreased the electron losses on the wall. The effects of magnetic field on the generation and propagation mechanisms of the microwave plasma were tentatively investigated based on a 2-D numerical model combining a coupled system of Maxwell's equations and continuity equations. The mobility of electrons and effective electric conductivity of the plasma were considered as a full tensor in the presence of magnetic field. Numerical results indicate that both cases of magnetic field in the axial-direction and radial-direction benefit the generation of a high-density plasma; the former one allows the microwave to propagate longer in the axis direction compared to the latter one. The time-averaged power flow density and the amplitude of the electric field on the inner rod of coaxial waveguide attenuate with the propagation of the microwave for both cases of with and without external magnetic field. The attenuation becomes smaller in the presence of appropriately higher axial-direction magnetic field, which allows more microwave energies to transmit along the axial direction. Meanwhile, the anisotropic properties of the plasma, like electron mobility, in the presence of the magnetic field confine more charged particles in the direction of the magnetic field line.

  17. Multipole expansion method for supernova neutrino oscillations

    SciTech Connect

    Duan, Huaiyu; Shalgar, Shashank E-mail: shashankshalgar@unm.edu

    2014-10-01

    We demonstrate a multipole expansion method to calculate collective neutrino oscillations in supernovae using the neutrino bulb model. We show that it is much more efficient to solve multi-angle neutrino oscillations in multipole basis than in angle basis. The multipole expansion method also provides interesting insights into multi-angle calculations that were accomplished previously in angle basis.

  18. The Physics of Ion Decoupling in Magnetized Plasma Explosions

    SciTech Connect

    Hewett, D; Larson, D; Brecht, S

    2011-02-08

    When a finite pulse of plasma expands into a magnetized background plasma, MHD predicts the pulse expel background plasma and its B-field - i.e. cause a magnetic 'bubble'. The expanding plasma is confined within the bubble, later to escape down the B-field lines. MHD suggests that the debris energy goes to expelling the B-field from the bubble volume and kinetic energy of the displaced background. For HANEs, this is far from the complete story. For many realistic HANE regimes, the long mean-free-path for collisions necessitates a Kinetic Ion Simulation Model (KISM). The most obvious effect is that the debris plasma can decouple and slip through the background plasma. The implications are: (1) the magnetic bubble is not as large as expected and (2) the debris is no longer confined within the magnetic bubble.

  19. HPAM: Hirshfeld partitioned atomic multipoles

    NASA Astrophysics Data System (ADS)

    Elking, Dennis M.; Perera, Lalith; Pedersen, Lee G.

    2012-02-01

    An implementation of the Hirshfeld (HD) and Hirshfeld-Iterated (HD-I) atomic charge density partitioning schemes is described. Atomic charges and atomic multipoles are calculated from the HD and HD-I atomic charge densities for arbitrary atomic multipole rank l on molecules of arbitrary shape and size. The HD and HD-I atomic charges/multipoles are tested by comparing molecular multipole moments and the electrostatic potential (ESP) surrounding a molecule with their reference ab initio values. In general, the HD-I atomic charges/multipoles are found to better reproduce ab initio electrostatic properties over HD atomic charges/multipoles. A systematic increase in precision for reproducing ab initio electrostatic properties is demonstrated by increasing the atomic multipole rank from l=0 (atomic charges) to l=4 (atomic hexadecapoles). Both HD and HD-I atomic multipoles up to rank l are shown to exactly reproduce ab initio molecular multipole moments of rank L for L⩽l. In addition, molecular dipole moments calculated by HD, HD-I, and ChelpG atomic charges only ( l=0) are compared with reference ab initio values. Significant errors in reproducing ab initio molecular dipole moments are found if only HD or HD-I atomic charges used. Program summaryProgram title: HPAM Catalogue identifier: AEKP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License v2 No. of lines in distributed program, including test data, etc.: 500 809 No. of bytes in distributed program, including test data, etc.: 13 424 494 Distribution format: tar.gz Programming language: C Computer: Any Operating system: Linux RAM: Typically, a few hundred megabytes Classification: 16.13 External routines: The program requires 'formatted checkpoint' files obtained from the Gaussian 03 or Gaussian 09 quantum chemistry program. Nature of problem: An ab initio

  20. Multipole expansions of gravitational radiation

    NASA Astrophysics Data System (ADS)

    Thorne, Kip S.

    1980-04-01

    This paper brings together, into a single unified notation, the multipole formalisms for gravitational radiation which various people have constructed. It also extends the results of previous workers. More specifically: Part One of this paper reviews the various scalar, vector, and tensor spherical harmonics used in the general relativity literature-including the Regge-Wheeler harmonics, the symmetric, trace-free ("STF") tensors of Sachs and Pirani, the Newman-Penrose spin-weighted harmonics, and the Mathews-Zerilli Clebsch-Gordan-coupled harmonics-which include "pure-orbital" harmonics and "pure-spin" harmonics. The relationships between the various harmonics are presented. Part One then turns attention to gravitational radiation. The concept of "local wave zone" is introduced to facilitate a clean separation of "wave generation" from "wave propagation." The generic radiation field in the local wave zone is decomposed into multipole components. The energy, linear momentum, and angular momentum in the waves are expressed as infinite sums of multipole contributions. Attention is then restricted to sources that admit a nonsingular, spacetime-covering de Donder coordinate system. (This excludes black holes.) In such a coordinate system the multipole moments of the radiation field are expressed as volume integrals over the source. For slow-motion systems, these source integrals are re-expressed as infinite power series in Lλ/≡(size of source)(reduced wavelength of waves). The slow-motion source integrals are then specialized to systems with weak internal gravity to yield (i) the standard Newtonian formulas for the multipole moments, (ii) the post-Newtonian formulas of Epstein and Wagoner, and (iii) post-post-Newtonian formulas. Part Two of this paper derives a multipole-moment wave-generation formalism for slow-motion systems with arbitrarily strong internal gravity, including systems that cannot be covered by de Donder coordinates. In this formalism one calculates

  1. Theory of electromagnetic fluctuations for magnetized multi-species plasmas

    SciTech Connect

    Navarro, Roberto E. Muñoz, Víctor; Araneda, Jaime; Moya, Pablo S.; Viñas, Adolfo F.; Valdivia, Juan A.

    2014-09-15

    Analysis of electromagnetic fluctuations in plasma provides relevant information about the plasma state and its macroscopic properties. In particular, the solar wind persistently sustains a small but detectable level of magnetic fluctuation power even near thermal equilibrium. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we derive general expressions for the plasma fluctuations in a multi-species plasma following arbitrary distribution functions. This formalism, which generalizes and includes previous works on the subject, is then applied to the generation of electromagnetic fluctuations propagating along a background magnetic field in a plasma of two proton populations described by drifting bi-Maxwellians.

  2. Dual-function magnetic structure for toroidal plasma devices

    DOEpatents

    Brown, Robert L.

    1978-01-01

    This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring.

  3. Photonic Weyl degeneracies in magnetized plasma

    PubMed Central

    Gao, Wenlong; Yang, Biao; Lawrence, Mark; Fang, Fengzhou; Béri, Benjamin; Zhang, Shuang

    2016-01-01

    Weyl particles are elusive relativistic fermionic particles with vanishing mass. While not having been found as an elementary particle, they are found to emerge in solid-state materials where three-dimensional bands develop a topologically protected point-like crossing, a so-called Weyl point. Photonic Weyl points have been recently realised in three-dimensional photonic crystals with complex structures. Here we report the presence of a novel type of plasmonic Weyl points in a naturally existing medium—magnetized plasma, in which Weyl points arise as crossings between purely longitudinal plasma modes and transverse helical propagating modes. These photonic Weyl points are right at the critical transition between a Weyl point with the traditional closed finite equifrequency surfaces and the newly proposed ‘type II' Weyl points with open equifrequency surfaces. Striking observable features of plasmon Weyl points include a half k-plane chirality manifested in electromagnetic reflection. Our study introduces Weyl physics into homogeneous photonic media, which could pave way for realizing new topological photonic devices. PMID:27506514

  4. Dynamics of runaway electrons in magnetized plasmas

    SciTech Connect

    Moghaddam-Taaheri, E.

    1986-01-01

    The evolution of a runaway electron tail driven by a subcritical dc electric field in a magnetized plasma is studied numerically using a quasi-linear numerical code (2-D in v- and k-space) based on the Ritz-Galerkin method and finite elements. Three different regimes in the evolution of the runaway tail depending on the strength of the dc electric field and the ratio of plasma to gyrofrequency, were found. The tail can be (a) stable and the electrons are accelerated to large parallel velocities, (b) unstable to the Cerenkov resonance due to the formation of a positive slope on the runaway tail, (c) unstable to the anomalous Doppler resonance instability driven by the large velocity anisotropy in the tail. Once an instability is triggered (Cerenkov or anomalous Doppler resonance) the tail relaxes into an isotropic distribution resulting in less acceleration. The synchrotron emission of the runaway electrons shows large enhancement in the radiation level at the high-frequency end of the spectrum during the pitch-angle scattering of the fast particles. The results are relevant to recent experimental data from the Princeton Large Torus (PLT) during current-drive experiments and to the microwave bursts observed during solar flares.

  5. A plasma generator utilizing the high intensity ASTROMAG magnets

    NASA Technical Reports Server (NTRS)

    Sullivan, James D.; Post, R. S.; Lane, B. G.; Tarrh, J. M.

    1986-01-01

    The magnet configuration for the proposed particle astrophysics magnet facility (ASTROMAG) on the space station includes a cusp magnetic field with an intensity of a few tesla. With these large magnets (or others) located in the outer ionosphere, many quite interesting and unique plasma physics experiments become possible. First there are studies utilizing the magnet alone to examine the supersonic, sub-Alfvenic interaction with the ambient medium; the scale length for the magnet perturbation is approx. 20 m. The magnetic field geometry when combined with the Earth's and their relative motion will give rise to a host of plasma phenomena: ring nulls, x-points, ion-acoustic and lower-hybrid shocks, electron heating (possible shuttle glow without a surface) launching of Alfvenwaves, etc. Second, active experiments are possible for a controlled study of fundamental plasma phenomena. A controlled variable species plasma can be made by using an RF ion source; use of two soft iron rings placed about the line cusp would give an adequate resonance zone (ECH or ICH) and a confining volume suitable for gas efficiency. The emanating plasma can be used to study free expansion of plasma along and across field lines (polar wind), plasma flows around the space platform, turbulent mixing in the wake region, long wavelength spectrum of convecting modes, plasma-dust interactions, etc.

  6. Magnetic tearing of plasma discharges due to nonuniform resistivity

    NASA Technical Reports Server (NTRS)

    Hassam, A. B.

    1988-01-01

    The rearrangement of current in a plasma discharge in response to resistivity nonuniformities within a magnetic surface is studied. It is shown that macroscopic magnetic islands develop about those surfaces where the nonuniformity is aligned with the magnetic field. If the nonuniformity and the field are not aligned anywhere, there is no current rearrangement; instead, relatively large plasma flows are set up. Such resistivity inhomogeneities can obtain in solar coronal loops and, in some circumstances, in tokamak discharges.

  7. Solitary and shock waves in magnetized electron-positron plasma

    SciTech Connect

    Lu, Ding; Li, Zi-Liang; Abdukerim, Nuriman; Xie, Bai-Song

    2014-02-15

    An Ohm's law for electron-positron (EP) plasma is obtained. In the framework of EP magnetohydrodynamics, we investigate nonrelativistic nonlinear waves' solutions in a magnetized EP plasma. In the collisionless limit, quasistationary propagating solitary wave structures for the magnetic field and the plasma density are obtained. It is found that the wave amplitude increases with the Mach number and the Alfvén speed. However, the dependence on the plasma temperature is just the opposite. Moreover, for a cold EP plasma, the existence range of the solitary waves depends only on the Alfvén speed. For a hot EP plasma, the existence range depends on the Alfvén speed as well as the plasma temperature. In the presence of collision, the electromagnetic fields and the plasma density can appear as oscillatory shock structures because of the dissipation caused by the collisions. As the collision frequency increases, the oscillatory shock structure becomes more and more monotonic.

  8. The magnetic pumping of plasmas with sawtooth waveforms

    NASA Technical Reports Server (NTRS)

    Borovsky, Joseph E.; Hansen, Paul J.

    1990-01-01

    The pumping of plasmas by sawtooth-waveform magnetic induction variations is studied theoretically and by means of computer simulations. A sawtooth is a cycle waveform that is characterized by a slow increase in the magnetic induction followed by a rapid drop in the induction. Two types of sawtooth pumping are analyzed, and the types classified as to whether or not the first adiabatic invariants of the plasma particles are conserved during the rapid drops in the magnetic induction. When the invariants are conserved, the sawtooth waveforms are found to be less efficient than square waves for pumping plasmas. When the adiabatic invariations are not conserved, the pumping efficiency is found to be a slight improvement over square waves. Both types of pumping are applied to a hypothetical tokamak plasma and it is concluded that neither type of sawtooth pumping is practical for heating magnetically confined fusion plasmas.

  9. Inhomogeneous Magnetic Field Geometry Light Ion Helicon Plasma Source

    NASA Astrophysics Data System (ADS)

    Mori, Yoshitaka; Nakashima, Hideki; Goulding, R. H.; Carter Baity, M. D., Jr.; Sparks, D. O.; Barber, G. C.; White, K. F.; Jaeger, E. F.; Chang-Díaz, F. R.; Squire, J. P.

    2002-11-01

    Helicon plasma source is a well-known high-density plasma source for many applications including plasma processing and fusion. However, most helicon research has been focused on a uniform static magnetic field and relatively heavy ions. Light ion helicon operation is more sensitive to magnetic field strength and geometry than heavy ions. The axially inhomogeneous Mini-Radio Frequency Test Facility (Mini-RFTF) has a capability for controlling static magnetic fields then is applicative for light ion source plasma operation. Inhomogeneous static magnetic field geometry also can procedure a high velocity to plasma exhaust when combined with ICRF heating enabling the possibility of use in plasma propulsion. In this poster, we will show how the source has been optimized for a hydrogen operation and a specific plasma propulsion concept: The Variable Specific Impulse Magnetoplasma Rocket (VASIMR). Measurements of the rf magnetic fields and profile of plasma parameters for several magnetic field strengths and geometries will be discussed. Comparisons with a RF modeling code EMIR3 also will be reported here.

  10. Performance Characterization of Ion Thruster with Isolated Magnet Rings

    NASA Astrophysics Data System (ADS)

    Arthur, Neil; Foster, John

    2016-10-01

    Many ion sources use magnetic multipole confinement to increase the primary electron containment length. The magnetic circuit increases ion source efficiency and plasma density. A multipole source consists of rings or rows of magnets of alternating polarity. In multipole sources, the bulk of the discharge current is collected at the magnet surface, through the relatively narrow leak width. Ion engines for space propulsion are one application of multipole ion sources. Here we characterize a four ring, broad beam ion source under simulated beam extraction using typical performance metrics for ion engines while biasing the magnetic rings individually. By biasing the magnetic cusps, through isolated, conformal electrodes placed on the magnet rings, the current distribution to each individual cusp can be modified. The effect of ring bias on ion beam current, propellant utilization efficiency, and discharge losses is measured over a broad range of ring bias. Previous experiments have shown that the current distribution to the rings can be controlled, and this current distribution has tangible effects on the plasma properties and ion source operation. The goal is to gain insight into which magnetic ring current distributions will yield enhancements in engine performance.

  11. Progress In Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Francis Y. C.; Kirkpatrick, Ronald C.; Knapp, Charles E.; Cassibry, Jason; Eskridge, Richard; Lee, Michael; Smith, James; Martin, Adam; Wu, S. T.; Schmidt, George; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    Magnetized target fusion (MTF) attempts to combine the favorable attributes of magnetic confinement fusion (MCF) for energy confinement with the attributes of inertial confinement fusion (ICF) for efficient compression heating and wall-free containment of the fusing plasma. It uses a material liner to compress and contain a magnetized plasma. For practical applications, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC).

  12. Multi-Scale Investigation of Sheared Flows In Magnetized Plasmas

    SciTech Connect

    Edward, Jr., Thomas

    2014-09-19

    Flows parallel and perpendicular to magnetic fields in a plasma are important phenomena in many areas of plasma science research. The presence of these spatially inhomogeneous flows is often associated with the stability of the plasma. In fusion plasmas, these sheared flows can be stabilizing while in space plasmas, these sheared flows can be destabilizing. Because of this, there is broad interest in understanding the coupling between plasma stability and plasma flows. This research project has engaged in a study of the plasma response to spatially inhomogeneous plasma flows using three different experimental devices: the Auburn Linear Experiment for Instability Studies (ALEXIS) and the Compact Toroidal Hybrid (CTH) stellarator devices at Auburn University, and the Space Plasma Simulation Chamber (SPSC) at the Naval Research Laboratory. This work has shown that there is a commonality of the plasma response to sheared flows across a wide range of plasma parameters and magnetic field geometries. The goal of this multi-device, multi-scale project is to understand how sheared flows established by the same underlying physical mechanisms lead to different plasma responses in fusion, laboratory, and space plasmas.

  13. Relativistic nonlinear plasma waves in a magnetic field

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Pellat, R.

    1975-01-01

    Five relativistic plane nonlinear waves were investigated: circularly polarized waves and electrostatic plasma oscillations propagating parallel to the magnetic field, relativistic Alfven waves, linearly polarized transverse waves propagating in zero magnetic field, and the relativistic analog of the extraordinary mode propagating at an arbitrary angle to the magnetic field. When the ions are driven relativistic, they behave like electrons, and the assumption of an 'electron-positron' plasma leads to equations which have the form of a one-dimensional potential well. The solutions indicate that a large-amplitude superluminous wave determines the average plasma properties.

  14. On the parametric transparency of a magnetized plasma slab

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1981-06-01

    A mechanism is proposed for the nonlinear transparency of a dense magnetized plasma slab to electromagnetic radiation. The mechanism is based on the parametric excitation of surface waves in a cold magnetized plasma slab. It is shown that a significant proportion of incident radiation will be able to penetrate the slab due to saturation caused by the nonlinear resonant absorption of the surface waves generated. The mechanism also predicts the presence of transmitted radiation at a frequency less than that of the incident radiation in a direction parallel to the incident pump-wave electric field, the external constant magnetic field and the plasma layer.

  15. Ideal plasma response to vacuum magnetic fields with resonant magnetic perturbations in non-axisymmetric tokamaks

    SciTech Connect

    Kim, Kimin; Ahn, J. -W.; Scotti, F.; Park, J. -K.; Menard, J. E.

    2015-09-03

    Ideal plasma shielding and amplification of resonant magnetic perturbations in non-axisymmetric tokamak is presented by field line tracing simulation with full ideal plasma response, compared to measurements of divertor lobe structures. Magnetic field line tracing simulations in NSTX with toroidal non-axisymmetry indicate the ideal plasma response can significantly shield/amplify and phase shift the vacuum resonant magnetic perturbations. Ideal plasma shielding for n = 3 mode is found to prevent magnetic islands from opening as consistently shown in the field line connection length profile and magnetic footprints on the divertor target. It is also found that the ideal plasma shielding modifies the degree of stochasticity but does not change the overall helical lobe structures of the vacuum field for n = 3. Furthermore, amplification of vacuum fields by the ideal plasma response is predicted for low toroidal mode n = 1, better reproducing measurements of strong striation of the field lines on the divertor plate in NSTX.

  16. Rayleigh-Taylor instability in quantum magnetized viscous plasma

    SciTech Connect

    Hoshoudy, G. A.

    2011-09-15

    Quantum effects on Rayleigh-Taylor instability of stratified viscous plasmas layer under the influence of vertical magnetic field are investigated. By linearly solving the viscous QMHD equations into normal mode, a forth-order ordinary differential equation is obtained to describe the velocity perturbation. Then the growth rate is derived for the case where a plasma with exponential density distribution is confined between two rigid planes. The results show that, the presence of vertical magnetic field beside the quantum effect will bring about more stability on the growth rate of unstable configuration for viscous plasma, which is greater than that of inviscous plasma.

  17. High Magnetic field generation for laser-plasma experiments

    SciTech Connect

    Pollock, B B; Froula, D H; Davis, P F; Ross, J S; Fulkerson, S; Bower, J; Satariano, J; Price, D; Glenzer, S H

    2006-05-01

    An electromagnetic solenoid was developed to study the effect of magnetic fields on electron thermal transport in laser plasmas. The solenoid, which is driven by a pulsed power system suppling 30 kJ, achieves magnetic fields of 13 T. The field strength was measured on the solenoid axis with a magnetic probe and optical Zeeman splitting. The measurements agree well with analytical estimates. A method for optimizing the solenoid design to achieve magnetic fields exceeding 20 T is presented.

  18. Improved Magnetic Field Generation Efficiency and Higher Temperature Spheromak Plasmas

    SciTech Connect

    Wood, R D; Hill, D N; McLean, H S; Hooper, E B; Hudson, B F; Moller, J M; Romero-Talamas, C A

    2008-09-15

    New understanding of the mechanisms governing the observed magnetic field generation limits on the sustained spheromak physics experiment has been obtained. Extending the duration of magnetic helicity injection during the formation of a spheromak and optimizing the ratio of injected current to bias flux produce higher magnetic field plasmas with record spheromak electron temperatures. To explore magnetic field buildup efficiency limits, the confinement region geometry was varied resulting in improved field buildup efficiencies.

  19. Photonic band gaps in one-dimensional magnetized plasma photonic crystals with arbitrary magnetic declination

    SciTech Connect

    Zhang Haifeng; Liu Shaobin; Kong Xiangkun

    2012-12-15

    In this paper, the properties of photonic band gaps and dispersion relations of one-dimensional magnetized plasma photonic crystals composed of dielectric and magnetized plasma layers with arbitrary magnetic declination are theoretically investigated for TM polarized wave based on transfer matrix method. As TM wave propagates in one-dimensional magnetized plasma photonic crystals, the electromagnetic wave can be divided into two modes due to the influence of Lorentz force. The equations for effective dielectric functions of such two modes are theoretically deduced, and the transfer matrix equation and dispersion relations for TM wave are calculated. The influences of relative dielectric constant, plasma collision frequency, incidence angle, plasma filling factor, the angle between external magnetic field and +z axis, external magnetic field and plasma frequency on transmission, and dispersion relation are investigated, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that plasma collision frequency cannot change the locations of photonic band gaps for both modes, and also does not affect the reflection and transmission magnitudes. The characteristics of photonic band gaps for both modes can be obviously tuned by relative dielectric constant, incidence angle, plasma filling factor, the angle between external magnetic field and +z axis, external magnetic field and plasma frequency, respectively. These results would provide theoretical instructions for designing filters, microcavities, and fibers, etc.

  20. Confinement of Plasma along Shaped Open Magnetic Fields from the Centrifugal Force of Supersonic Plasma Rotation

    SciTech Connect

    Teodorescu, C.; Young, W. C.; Swan, G. W. S.; Ellis, R. F.; Hassam, A. B.; Romero-Talamas, C. A.

    2010-08-20

    Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic ExB rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

  1. Magnetized Target Fusion Propulsion: Plasma Injectors for MTF Guns

    NASA Technical Reports Server (NTRS)

    Griffin, Steven T.

    2003-01-01

    To achieve increased payload size and decreased trip time for interplanetary travel, a low mass, high specific impulse, high thrust propulsion system is required. This suggests the need for research into fusion as a source of power and high temperature plasma. The plasma would be deflected by magnetic fields to provide thrust. Magnetized Target Fusion (MTF) research consists of several related investigations into these topics. These include the orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the gun as it relates to plasma initiation and repeatability are under investigation. One of the items under development is the plasma injector. This is a surface breakdown driven plasma generator designed to function at very low pressures. The performance, operating conditions and limitations of these injectors need to be determined.

  2. An O(N) and parallel approach to integral problems by a kernel-independent fast multipole method: Application to polarization and magnetization of interacting particles

    SciTech Connect

    Jiang, Xikai; Li, Jiyuan; Zhao, Xujun; Qin, Jian; Karpeev, Dmitry; Hernandez-Ortiz, Juan; de Pablo, Juan J.; Heinonen, Olle

    2016-08-10

    Large classes of materials systems in physics and engineering are governed by magnetic and electrostatic interactions. Continuum or mesoscale descriptions of such systems can be cast in terms of integral equations, whose direct computational evaluation requires O(N2) operations, where N is the number of unknowns. Such a scaling, which arises from the many-body nature of the relevant Green's function, has precluded wide-spread adoption of integral methods for solution of large-scale scientific and engineering problems. In this work, a parallel computational approach is presented that relies on using scalable open source libraries and utilizes a kernel-independent Fast Multipole Method (FMM) to evaluate the integrals in O(N) operations, with O(N) memory cost, thereby substantially improving the scalability and efficiency of computational integral methods. We demonstrate the accuracy, efficiency, and scalability of our approach in the context of two examples. In the first, we solve a boundary value problem for a ferroelectric/ferromagnetic volume in free space. In the second, we solve an electrostatic problem involving polarizable dielectric bodies in an unbounded dielectric medium. Lastly, the results from these test cases show that our proposed parallel approach, which is built on a kernel-independent FMM, can enable highly efficient and accurate simulations and allow for considerable flexibility in a broad range of applications.

  3. Understanding of Edge Plasmas in Magnetic Fusion Energy Devices

    SciTech Connect

    Rognlien, T

    2004-11-01

    A limited overview is given of the theoretical understanding of edge plasmas in fusion devices. This plasma occupies the thin region between the hot core plasma and material walls in magnetically confinement configurations. The region is often formed by a change in magnetic topology from close magnetic field lines (i.e., the core region) and open field lines that contact material surfaces (i.e., the scrape-off layer [SOL]), with the most common example being magnetically diverted tokamaks. The physics of this region is determined by the interaction of plasma with neutral gas in the presence of plasma turbulence, with impurity radiation being an important component. Recent advances in modeling strong, intermittent micro-turbulent edge-plasma transport is given, and the closely coupled self-consistent evolution of the edge-plasma profiles in tokamaks. In addition, selected new results are given for the characterization of edge-plasmas behavior in the areas of edge-pedestal relaxation and SOL transport via Edge-Localize Modes (ELMs), impurity formation including dust, and magnetic field-line stochasticity in tokamaks.

  4. Improvement of uniformity in a weakly magnetized inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Lee, W. H.; Cheong, H. W.; Kim, J. W.; Whang, K. W.

    2015-12-01

    Magnetic fields are applied to inductively coupled plasma (ICP) to achieve high plasma densities using electromagnets. If the magnetic fields are set up such that the magnitude of magnetic flux density on the substrate decreases with both radial and axial distances from the substrate’s center (here after referred to as M-ICP-A), the plasma density increases by 237% compared with that for ICP although the non-uniformity of the plasma density for M-ICP-A (11.1%) is higher than that for ICP (10.9%). As the rate of decrease in the magnitude of magnetic flux density on the substrate increases both radially and axially, the non-uniformity in the plasma density increases further. The increase in the non-uniformity for M-ICP-A was confirmed to arise from the flute instability. To suppress the flute instability, we arranged the magnitude of magnetic flux density on the substrate to increase with increasing distance from the substrate center both radially and axially (here after referred to as M-ICP-V). In this configuration, plasma fluctuations were not observed, hence the plasma density non-uniformity was lowered to 8.1%, although the measured plasma density was higher than that for M-ICP-A. The oxide etch-rate non-uniformity in M-ICP-V (2.5%) was also lower than that for ICP (5.2%) or that for M-ICP-A (21.4%).

  5. Anomalous skin effects in a weakly magnetized degenerate electron plasma

    NASA Astrophysics Data System (ADS)

    Abbas, G.; Sarfraz, M.; Shah, H. A.

    2014-09-01

    Fully relativistic analysis of anomalous skin effects for parallel propagating waves in a weakly magnetized degenerate electron plasma is presented and a graphical comparison is made with the results obtained using relativistic Maxwellian distribution function [G. Abbas, M. F. Bashir, and G. Murtaza, Phys. Plasmas 18, 102115 (2011)]. It is found that the penetration depth for R- and L-waves for degenerate case is qualitatively small in comparison with the Maxwellian plasma case. The quantitative reduction due to weak magnetic field in the skin depth in R-wave for degenerate plasma is large as compared to the non-degenerate one. By ignoring the ambient magnetic field, previous results for degenerate field free case are salvaged [A. F. Alexandrov, A. S. Bogdankevich, and A. A. Rukhadze, Principles of Plasma Electrodynamics (Springer-Verlag, Berlin/Heidelberg, 1984), p. 90].

  6. Surface electromagnetic wave equations in a warm magnetized quantum plasma

    SciTech Connect

    Li, Chunhua; Yang, Weihong; Wu, Zhengwei; Chu, Paul K.

    2014-07-15

    Based on the single-fluid plasma model, a theoretical investigation of surface electromagnetic waves in a warm quantum magnetized inhomogeneous plasma is presented. The surface electromagnetic waves are assumed to propagate on the plane between a vacuum and a warm quantum magnetized plasma. The quantum magnetohydrodynamic model includes quantum diffraction effect (Bohm potential), and quantum statistical pressure is used to derive the new dispersion relation of surface electromagnetic waves. And the general dispersion relation is analyzed in some special cases of interest. It is shown that surface plasma oscillations can be propagated due to quantum effects, and the propagation velocity is enhanced. Furthermore, the external magnetic field has a significant effect on surface wave's dispersion equation. Our work should be of a useful tool for investigating the physical characteristic of surface waves and physical properties of the bounded quantum plasmas.

  7. Anomalous skin effects in a weakly magnetized degenerate electron plasma

    SciTech Connect

    Abbas, G. Sarfraz, M.; Shah, H. A.

    2014-09-15

    Fully relativistic analysis of anomalous skin effects for parallel propagating waves in a weakly magnetized degenerate electron plasma is presented and a graphical comparison is made with the results obtained using relativistic Maxwellian distribution function [G. Abbas, M. F. Bashir, and G. Murtaza, Phys. Plasmas 18, 102115 (2011)]. It is found that the penetration depth for R- and L-waves for degenerate case is qualitatively small in comparison with the Maxwellian plasma case. The quantitative reduction due to weak magnetic field in the skin depth in R-wave for degenerate plasma is large as compared to the non-degenerate one. By ignoring the ambient magnetic field, previous results for degenerate field free case are salvaged [A. F. Alexandrov, A. S. Bogdankevich, and A. A. Rukhadze, Principles of Plasma Electrodynamics (Springer-Verlag, Berlin/Heidelberg, 1984), p. 90].

  8. Penetration of Magnetosheath Plasma into Dayside Magnetosphere. 2. ; Magnetic Field in Plasma Filaments

    NASA Technical Reports Server (NTRS)

    Lyatsky, Wladislaw; Pollock, Craig; Goldstein, Melvyn L.; Lyatskaya, Sonya Inna; Avanov, Levon Albert

    2016-01-01

    In this paper, we examined plasma structures (filaments), observed in the dayside magnetosphere but containing magnetosheath plasma. These filaments show the stable antisunward motion (while the ambient magnetospheric plasma moved in the opposite direction) and the existence of a strip of magnetospheric plasma, separating these filaments from the magnetosheath. These results, however, contradict both theoretical studies and simulations by Schindler (1979), Ma et al. (1991), Dai and Woodward (1994, 1998), and other researchers, who reported that the motion of such filaments through the magnetosphere is possible only when their magnetic field is directed very close to the ambient magnetic field, which is not the situation that is observed. In this study, we show that this seeming contradiction may be related to different events as the theoretical studies and simulations are related to the case when the filament magnetic field is about aligned with filament orientation, whereas the observations show that the magnetic field in these filaments may be rotating. In this case, the rotating magnetic field, changing incessantly its direction, drastically affects the penetration of plasma filaments into the magnetosphere. In this case, the filaments with rotating magnetic field, even if in each moment it is significantly inclined to the ambient magnetic field, may propagate through the magnetosphere, if their average (for the rotation period) magnetic field is aligned with the ambient magnetic field. This shows that neglecting the rotation of magnetic field in these filaments may lead to wrong results.

  9. Plasma Rotation Control Experiment in a Strongly Diverging Magnetic Field

    NASA Astrophysics Data System (ADS)

    Terasaka, Kenichiro; Furuta, Kanshi; Yoshimura, Shinji; Aramaki, Mitsutoshi; Tanaka, Masayoshi Y.

    2016-10-01

    It has been recognized that the plasma rotation affects the plasma flow structure along the magnetic field line. However, the effect of plasma rotation on structure formation in a strongly diverging magnetic field with magnetized electrons and unmagnetized ions has not been fully understood, so far. Understanding the flow structure formation in an ion-unmagnetized plasma is essential to control ion streamline detachment from the magnetic field line and also necessary to study the astrophysical phenomena in laboratory. In order to clarify the effect of plasma rotation in a diverging magnetic field, we have performed the plasma rotation control experiment in the HYPER-II device at Kyushu Univ., Japan. A set of cylindrical electrode was utilized to control the radial electric field, and the profile of azimuthal E × B rotation has been changed. We present the experimental results on the electron density pileup and the flow reversal appeared in the rotating plasma. This study was supported by JSPS KAKENHI Grant Number 16K05633.

  10. Magnetic Turbulence in Colliding Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Collette, A.; Gekelman, W.; Vincena, S.

    2007-05-01

    The expansion and interaction of dense plasmas in the presence of a magnetized background plasma is important in many astrophysical processes, among them coronal mass ejections and the many examples of plasma jets from astrophotography. Turbulence is expected to be present in many such configurations. We describe a series of experiments which involve the collision of two dense (initially, n > 1015cm-3) laser-produced plasmas within an ambient, highly magnetized background plasma. The laser-produced plasmas form diamagnetic cavities in which a large percentage of the background magnetic field (600G) has been expelled. First-stage observations of these structures have been completed using a fast (3ns exposure) camera. The photographs indicate complicated structure at late times, in addition to coherent corrugated structures on the bubble surfaces. The data hint at the presence of turbulence in the interaction. The second stage of observation will consist of direct investigation of the magnetic field using probes. A novel diagnostic system composed of small (300-500 micron) 3-axis differential magnetic field probes in conjunction with a ceramic motor system capable of extremely fine (sub-micron) positioning accuracy is currently under development. An ensemble of magnetic field data from fixed and movable probes makes possible the calculation of the cross-spectral function. Initial data from photography and a prototype probe will be presented.

  11. MAGNETIC END CLOSURES FOR PLASMA CONFINING AND HEATING DEVICES

    DOEpatents

    Post, R.F.

    1963-08-20

    More effective magnetic closure field regions for various open-ended containment magnetic fields used in fusion reactor devices are provided by several spaced, coaxially-aligned solenoids utilized to produce a series of nodal field regions of uniform or, preferably, of incrementally increasing intensity separated by lower intensity regions outwardly from the ends of said containment zone. Plasma sources may also be provided to inject plasma into said lower intensity areas to increase plasma density therein. Plasma may then be transported, by plasma diffusion mechanisms provided by the nodal fields, into the containment field. With correlated plasma densities and nodal field spacings approximating the mean free partl cle collision path length in the zones between the nodal fields, optimum closure effectiveness is obtained. (AEC)

  12. Effect of bias application to plasma density in weakly magnetized inductively coupled plasma

    SciTech Connect

    Kim, Hyuk; Lee, Woohyun; Park, Wanjae; Whang, Ki-Woong

    2013-07-15

    Independent control of the ion flux and energy can be achieved in a dual frequency inductively coupled plasma (ICP) system. Typically, the plasma density is controlled by the high-frequency antenna radio-frequency (RF) power and the ion energy is controlled by the low-frequency bias RF power. Increasing the bias power has been known to cause a decrease in the plasma density in capacitively coupled discharge systems as well as in ICP systems. However, an applied axial magnetic field was found to sustain or increase the plasma density as bias power is increased. Measurements show higher electron temperatures but lower plasma densities are obtained in ordinary ICP systems than in magnetized ICP systems under the same neutral gas pressure and RF power levels. Explanations for the difference in the behavior of plasma density with increasing bias power are given in terms of the difference in the heating mechanism in ordinary unmagnetized and magnetized ICP systems.

  13. Simulating Magnetized Laboratory Plasmas with Smoothed Particle Hydrodynamics

    SciTech Connect

    Johnson, Jeffrey N.

    2009-01-01

    The creation of plasmas in the laboratory continues to generate excitement in the physics community. Despite the best efforts of the intrepid plasma diagnostics community, the dynamics of these plasmas remains a difficult challenge to both the theorist and the experimentalist. This dissertation describes the simulation of strongly magnetized laboratory plasmas with Smoothed Particle Hydrodynamics (SPH), a method born of astrophysics but gaining broad support in the engineering community. We describe the mathematical formulation that best characterizes a strongly magnetized plasma under our circumstances of interest, and we review the SPH method and its application to astrophysical plasmas based on research by Phillips [1], Buerve [2], and Price and Monaghan [3]. Some modifications and extensions to this method are necessary to simulate terrestrial plasmas, such as a treatment of magnetic diffusion based on work by Brookshaw [4] and by Atluri [5]; we describe these changes as we turn our attention toward laboratory experiments. Test problems that verify the method are provided throughout the discussion. Finally, we apply our method to the compression of a magnetized plasma performed by the Compact Toroid Injection eXperiment (CTIX) [6] and show that the experimental results support our computed predictions.

  14. Plasma expansion in the presence of a dipole magnetic field

    SciTech Connect

    Winske, D.; Omidi, N.

    2005-07-15

    Simulations of the initial expansion of a plasma injected into a stationary magnetized background plasma in the presence of a dipole magnetic field are carried out in two dimensions with a kinetic ion, massless fluid electron (hybrid) electromagnetic code. For small values of the magnetic dipole, the injected ions have large gyroradii compared to the scale length of the dipole field and are essentially unmagnetized. As a result, these ions expand, excluding the ambient magnetic field and plasma to form a diamagnetic cavity. However, for stronger magnetic dipoles, the ratio of the gyroradii of the injected ions to the dipole field scale length is small so that they remain magnetized, and hence trapped in the dipole field, as they expand. The trapping and expansion then lead to additional plasma currents and resulting magnetic fields that not only exclude the background field but also interact with the dipole field in a more complex manner that stretches the closed dipole field lines. A criterion to distinguish between the two regimes is derived and is then briefly discussed in the context of applying the results to the plasma sail scheme for the propulsion of small spacecraft in the solar wind.

  15. Collective dynamics and transport in extremely magnetized dusty plasmas

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter

    2016-09-01

    We have built an experimental setup to realize and observe rotating dusty plasmas in a co-rotating frame. Based on the Larmor theorem, the ``RotoDust'' setup is able to create effective magnetizations, mimicked by the Coriolis inertial force, in strongly coupled dusty plasmas that are impossible to approach with superconducting magnets. At the highest rotation speed, we have achieved effective magnetic fields of 3200 T. The effective magnetization β =ωc /ωp (ratio of cyclotron to plasma frequency) reaches 0.76 which is typical for many strongly magnetized and strongly correlated plasmas in compact astrophysical objects. The analysis of the wave spectra as observed in the rotating frame clearly shows the equivalence of the rotating dust cloud and a magnetized plasma. Further, the analysis of the mean square displacement (MSD) and the velocity autocorrelation function (VAC) revealed the transport parameters diffusion and viscosity, which are in reasonable agreement with numerical predictions for magnetized 2D Yukawa systems. Small degree of super-diffusion is observed. This research was supported by grant NKFIH K-115805 and the Janos Bolyai Research Scholarship of the HAS.

  16. Magnetic microstructure and magnetic properties of spark plasma sintered NdFeB magnets

    NASA Astrophysics Data System (ADS)

    Huang, Y. L.; Wang, Y.; Hou, Y. H.; Wang, Y. L.; Wu, Y.; Ma, S. C.; Liu, Z. W.; Zeng, D. C.; Tian, Y.; Xia, W. X.; Zhong, Z. C.

    2016-02-01

    Nanocrystalline NdFeB magnets were prepared by spark plasma sintering (SPS) technique using melt-spun ribbons as starting materials. A distinct two-zone structure with coarse grain zone and fine grain zone was formed in the SPSed magnets. Multi-domain particle in coarse grain zone and exchange interaction domain for fine grain zone were observed. Intergranular non-magnetic phase was favorable to improve the coercivity due to the enhancement of domain wall pinning effects and increased exchange-decouple. The remanent polarization of 0.83 T, coercivity of 1516 kA/m, and maximum energy product of 118 kJ/m3 are obtained for an isotropic magnet.

  17. Accumulative coupling between magnetized tenuous plasma and gravitational waves

    NASA Astrophysics Data System (ADS)

    Zhang, Fan

    2017-01-01

    This talk presents solutions to the plasma waves induced by a plane gravitational wave (GW) train travelling through a region of strongly magnetized plasma. The computations constitute a very preliminary feasibility study for a possible ultra-high frequency gravitational wave detector, meant to take advantage of the observation that the plasma current is proportional to the GW amplitude, and not its square. This work is supported in part by NSFC Grant Number 11503003.

  18. Development of a multi-pole magnetorheological brake

    NASA Astrophysics Data System (ADS)

    Shiao, Yaojung; Nguyen, Quang-Anh

    2013-06-01

    This paper presents a new approach in the design and optimization of a novel multi-pole magnetorheological (MR) brake that employs magnetic flux more effectively on the surface of the rotor. MR brakes with conventional single ring-type electromagnetic poles have reached the limits of torque enhancement. One major reason is the limitation of the magnetic field strength within the active area of the MR fluid due to the geometric constraints of the coil. The multi-pole MR brake design features multiple electromagnetic poles surrounded by several coils. As a result, the active chaining areas for the MR fluid are greatly increased, and significant brake torque improvement is achieved. The coil structure, as a part of the stator, becomes flexible and customizable in terms of space usage for the winding and bobbin design. In addition, this brake offers extra options in its dimensions for torque enhancement because either the radial or the axial dimensions of the rotor can be increased. Magnetic circuit analysis was conducted to analyze the effects of the design parameters on the field torque. After that, simulations were done to find the optimal design under all major geometric constraints with a given power supply. The results show that the multi-pole MR brake provides a considerable braking torque increase while maintaining a compact and solid design. This is confirmation of its feasibility in actual braking applications.

  19. Dust-Plasma Sheath in an Oblique Magnetic Field

    SciTech Connect

    Foroutan, G.; Mehdipour, H.

    2008-09-07

    Using numerical simulations of the multi fluid equations the structure of the magnetized sheath near a plasma boundary is studied in the presence of charged dust particles. The dependence of the electron, ion, and dust densities as well as the electrostatic potential, dust charge, and ion normal velocity, on the magnetic field strength and the edge dust number density is investigated.

  20. Nonlinear dynamics of large amplitude modes in a magnetized plasma

    SciTech Connect

    Brodin, G.; Stenflo, L.

    2014-12-15

    We derive two equations describing the coupling between electromagnetic and electrostatic oscillations in one-dimensional geometry in a magnetized cold and non-relativistic plasma. The nonlinear interaction between the wave modes is studied numerically. The effects of the external magnetic field strength and the initial electromagnetic polarization are of particular interest here. New results can, thus, be identified.

  1. Simultaneous Excitation and Analysis of Three Instabilities in Magnetized Plasma

    SciTech Connect

    Dimitriu, D. G.; Ionita, C.; Schrittwieser, R. W.

    2008-03-19

    Experimental results are presented on the simultaneous excitation of three low-frequency instabilities in the magnetized plasma column of a Q-machine, namely the potential relaxation instability, the electrostatic ion-cyclotron instability and the Kelvin-Helmholtz instability. The influence of the magnetic field intensity on the appearance of these instabilities was investigated.

  2. Solitary surface waves on a magnetized plasma cylinder

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.; Sünder, D.

    1985-02-01

    We analyse high-frequency electrostatic solitary surface waves that propagate along a plasma cylinder in the presence of a constant axial magnetic field. The width of such a solitary wave, which is found to be inversely proportional to its amplitude, is expressed as a function of the magnitude of the external magnetic field.

  3. On the ion acoustic obliquely propagation in magnetized inhomogeneous plasmas

    NASA Astrophysics Data System (ADS)

    Mowafy, A. E.; El-Shewy, E. K.; Abdelwahed, H. G.

    2017-02-01

    Inhomogeneous multi-component magnetized plasmas containing inertial ions, nonthermal electrons, and Boltzmannian positrons have been investigated theoretically. Variable coefficients Zakharov Kuznetsov (VZK) equation has been derived in a small amplitude limit. It is found that the propagation directions, positron parameters and magnetic field affected the properties of propagation of positive-negative solitary waves.

  4. Chirality-induced negative refraction in magnetized plasma

    SciTech Connect

    Guo, B.

    2013-09-15

    Characteristic equations in magnetized plasma with chirality are derived in simple formulations and the dispersion relations for propagation parallel and perpendicular to the external magnetic field are studied in detail. With the help of the dispersion relations of each eigenwave, the author explores chirality-induced negative refraction in magnetized plasma and investigates the effects of parameters (i.e., chirality degree, external magnetic field, etc.) on the negative refraction. The results show that the chirality is the necessary and only one factor which leads to negative refraction without manipulating electrical permittivity and magnetic permeability. Both increasing the degree of chirality and reducing the external magnetic field can result in greater range negative refraction. Parameter dependence of the effects is calculated and discussed.

  5. Plasma plume dynamics in magnetically assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Haverkamp, J. D.; Bourham, M. A.; Du, S.; Narayan, J.

    2009-01-01

    The expansion of a laser produced plasma perpendicular to a magnetic field is studied with a quadruple Langmuir probe and a B-dot probe. In regions where the kinetic beta is less than one, we find plume deceleration and weak displacement of the magnetic field. As the plume expands into regions of weak magnetic field, plume deceleration stops and the displacement of the magnetic field is large. The diffusion time of the magnetic field lines was consistent with anomalously large resistivity driven by the presence of an instability. Electron temperatures are larger than in the field-free case due to Ohmic heating mediated by the anomalously large resistivity.

  6. Charge Buildup in Magnetized Process Plasma

    NASA Astrophysics Data System (ADS)

    Namura, Takashi; Okada, Hiroyuki; Naitoh, Yasushi; Todokoro, Yoshihiro; Inoue, Morio

    1991-07-01

    The charge buildup in a magnetron etcher has been studied experimentally for two different magnet arrangements and theoretically on the basis of an equivalent circuit model. Wafer charging measured with a metal-Si3N4-SiO2-Si (MNOS) capacitor is negative along the centerline of the magnet poles and positive between the magnets in both cases. Wafer charging is explained either by curtent crowding at the center of the magnet poles or by the nonambipolar diffusion effect.

  7. Propagation of intense laser pulses in strongly magnetized plasmas

    SciTech Connect

    Yang, X. H. Ge, Z. Y.; Xu, B. B.; Zhuo, H. B.; Ma, Y. Y.; Shao, F. Q.; Yu, W.; Xu, H.; Yu, M. Y.; Borghesi, M.

    2015-06-01

    Propagation of intense circularly polarized laser pulses in strongly magnetized inhomogeneous plasmas is investigated. It is shown that a left-hand circularly polarized laser pulse propagating up the density gradient of the plasma along the magnetic field is reflected at the left-cutoff density. However, a right-hand circularly polarized laser can penetrate up the density gradient deep into the plasma without cutoff or resonance and turbulently heat the electrons trapped in its wake. Results from particle-in-cell simulations are in good agreement with that from the theory.

  8. Observations of Magnetic Reconnection and Plasma Dynamics in Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    DiBraccio, Gina A.

    Mercury's magnetosphere is formed as a result of the supersonic solar wind interacting with the planet's intrinsic magnetic field. The combination of the weak planetary dipole moment and intense solar wind forcing of the inner heliosphere creates a unique space environment, which can teach us about planetary magnetospheres. In this work, we analyze the first in situ orbital observations at Mercury, provided by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Magnetic reconnection and the transport of plasma and magnetic flux are investigated using MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer measurements. Here, we report our results on the effect of magnetic reconnection and plasma dynamics on Mercury's space environment: (1) Mercury's magnetosphere is driven by frequent, intense magnetic reconnection observed in the form of magnetic field components normal to the magnetopause, BN, and as helical bundles of flux, called magnetic flux ropes, in the cross-tail current sheet. The high reconnection rates are determined to be a direct consequence of the low plasma beta, the ratio of plasma to magnetic pressure, in the inner heliosphere. (2) As upstream solar wind conditions vary, we find that reconnection occurs at Mercury's magnetopause for all orientations of the interplanetary magnetic field, independent of shear angle. During the most extreme solar wind forcing events, the influence of induction fields generated within Mercury's highly conducting core are negated by erosion due to persistent magnetopause reconnection. (3) We present the first observations of Mercury's plasma mantle, which forms as a result of magnetopause reconnection and allows solar wind plasma to enter into the high-latitude magnetotail through the dayside cusps. The energy dispersion observed in the plasma mantle protons is used to infer the cross-magnetosphere electric field, providing a direct measurement of solar wind momentum

  9. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  10. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much_lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  11. A soliton gas model for astrophysical magnetized plasma turbulence

    NASA Astrophysics Data System (ADS)

    Spangler, S. R.; Sheerin, J. P.

    1982-06-01

    Plasma turbulence is considered as an ensemble of solitons. The derivation of the Alfven soliton by Spangler and Sheering (1981) is reviewed, and expressions are derived for the magnetic irregularity spectrum and the relationship between the magnetic and density irregularity power spectra. A derived expression also provides the answer to the question of the correlation between magnetic field and density enhancements. The properties of the turbulence model are compared with observations of plasma turbulence in the solar wind, and are found to reasonably account for them.

  12. Modified Debye screening potential in a magnetized quantum plasma

    NASA Astrophysics Data System (ADS)

    Salimullah, M.; Hussain, A.; Sara, I.; Murtaza, G.; Shah, H. A.

    2009-07-01

    The effects of quantum mechanical influence and uniform static magnetic field on the Shukla-Nambu-Salimullah potential in an ultracold homogeneous electron-ion Fermi plasma have been examined in detail. It is noticed that the strong quantum effect arising through the Bohm potential and the ion polarization effect can give rise to a new oscillatory behavior of the screening potential beyond the shielding cloud which could explain a new type of possible robust ordered structure formation in the quantum magnetoplasma. However, the magnetic field enhances the Debye length perpendicular to the magnetic field in the weak quantum limit of the quantum plasma.

  13. Magnetic control of particle injection in plasma based accelerators.

    PubMed

    Vieira, J; Martins, S F; Pathak, V B; Fonseca, R A; Mori, W B; Silva, L O

    2011-06-03

    The use of an external transverse magnetic field to trigger and to control electron self-injection in laser- and particle-beam driven wakefield accelerators is examined analytically and through full-scale particle-in-cell simulations. A magnetic field can relax the injection threshold and can be used to control main output beam features such as charge, energy, and transverse dynamics in the ion channel associated with the plasma blowout. It is shown that this mechanism could be studied using state-of-the-art magnetic fields in next generation plasma accelerator experiments.

  14. On the Magnetic Flux Conservation in the Partially Ionzied Plasma

    NASA Astrophysics Data System (ADS)

    Tsap, Yu.; Kopylova, Yu.

    2014-12-01

    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 magnetic flux is not sufficiently correct due to the formal dependence of the magnetic diffusion on a selected frame of reference. Thes ignificance of understanding of the physical nature for the dissipation and diffusion of the magnetic field in the partially ionized plasma as well as consequences of obtained results are discussed.

  15. MHD Simulations of the Plasma Flow in the Magnetic Nozzle

    NASA Technical Reports Server (NTRS)

    Smith, T. E. R.; Keidar, M.; Sankaran, K.; olzin, K. A.

    2013-01-01

    The magnetohydrodynamic (MHD) flow of plasma through a magnetic nozzle is simulated by solving the governing equations for the plasma flow in the presence of an static magnetic field representing the applied nozzle. This work will numerically investigate the flow and behavior of the plasma as the inlet plasma conditions and magnetic nozzle field strength are varied. The MHD simulations are useful for addressing issues such as plasma detachment and to can be used to gain insight into the physical processes present in plasma flows found in thrusters that use magnetic nozzles. In the model, the MHD equations for a plasma, with separate temperatures calculated for the electrons and ions, are integrated over a finite cell volume with flux through each face computed for each of the conserved variables (mass, momentum, magnetic flux, energy) [1]. Stokes theorem is used to convert the area integrals over the faces of each cell into line integrals around the boundaries of each face. The state of the plasma is described using models of the ionization level, ratio of specific heats, thermal conductivity, and plasma resistivity. Anisotropies in current conduction due to Hall effect are included, and the system is closed using a real-gas equation of state to describe the relationship between the plasma density, temperature, and pressure.A separate magnetostatic solver is used to calculate the applied magnetic field, which is assumed constant for these calculations. The total magnetic field is obtained through superposition of the solution for the applied magnetic field and the self-consistently computed induced magnetic fields that arise as the flowing plasma reacts to the presence of the applied field. A solution for the applied magnetic field is represented in Fig. 1 (from Ref. [2]), exhibiting the classic converging-diverging field pattern. Previous research was able to demonstrate effects such as back-emf at a super-Alfvenic flow, which significantly alters the shape of the

  16. Implicit Methods for the Magnetohydrodynamic Description of Magnetically Confined Plasmas

    SciTech Connect

    Jardin, S C

    2010-09-28

    Implicit algorithms are essential for predicting the slow growth and saturation of global instabilities in today’s magnetically confined fusion plasma experiments. Present day algorithms for obtaining implicit solutions to the magnetohydrodynamic (MHD) equations for highly magnetized plasma have their roots in algorithms used in the 1960s and 1970s. However, today’s computers and modern linear and non-linear solver techniques make practical much more comprehensive implicit algorithms than were previously possible. Combining these advanced implicit algorithms with highly accurate spatial representations of the vector fields describing the plasma flow and magnetic fields and with improved methods of calculating anisotropic thermal conduction now makes possible simulations of fusion experiments using realistic values of plasma parameters and actual configuration geometry.

  17. Plasma (Accretion) Disks with High Magnetic Energy Densities

    NASA Astrophysics Data System (ADS)

    Rousseau, F.; Coppi, B.

    2006-04-01

    ``Corrugated'' plasma disks can form in the dominant gravity of a central object when the peak plasma pressure in the disk is of the same order as that of the pressure of the ``external'' magnetic field, while the magnetic field resulting from internal plasma currents is of the same order as the external field. The corrugation refers to a periodic variation of the plasma density in a region around the equatorial plane. The considered structure represents a transition between a ``classical'' accretion disk and a ``rings sequence'' configuration^2. The common feature of the ``corrugated'' and the ``rings sequence'' configurations is the ``crystal'' structure of the magnetic surfaces that consist of a sequence of pairs of oppositely directed toroidal current density filaments. The connection between the characteristics of these configurations and those of the marginally stable ballooning modes that can be found in a model accretion disk is pointed out and analyzed.

  18. Collimation of laser-produced plasmas using axial magnetic field

    SciTech Connect

    Roy, Amitava; Harilal, Sivanandan S.; Hassan, Syed M.; Endo, Akira; Mocek, Tomas; Hassanein, A.

    2015-06-01

    We investigated the expansion dynamics of laser-produced plasmas expanding into an axial magnetic field. Plasmas were generated by focusing 1.064 µm Nd:YAG laser pulses onto a planar tin target in vacuum and allowed to expand into a 0.5 T magnetic-filed where field lines were aligned along the plume expansion direction. Gated images employing intensified CCD showed focusing of the plasma plume, which were also compared with results obtained using particle-in-cell modelling methods. The estimated density and temperature of the plasma plumes employing emission spectroscopy revealed significant changes in the presence and absence of the 0.5T magnetic field. In the presence of the field, the electron temperature is increased with distance from the target, while the density showed opposite effects.

  19. Extraction characteristics of ? ions in a magnetized sheet plasma

    NASA Astrophysics Data System (ADS)

    Sanchez, Jose Karl Charles D.; Ramos, Henry J.

    1996-08-01

    A sheet plasma of thickness several millimetres was produced by a combination of a pair of strong dipole magnets with opposing fields and a pair of Helmholtz coils producing a magnetic mirror field. A ferrite magnet and a coreless magnetic coil encased within the limiters add to the mirror field, enhancing quiescence in the plasma. The negative hydrogen ions produced in the peripheral region of the sheet plasma were extracted with a 0963-0252/5/3/009/img2 deflection mass spectrometer. Maximum negative ion current of about 0.9 0963-0252/5/3/009/img3A for an initial gas filling pressure of 3 mTorr was observed when the plasma electrode was negatively biased near the value of the plasma potential and when the mass spectrometer coil current generated a B field intensity equal to 691 G. The ratio of the negative ion density and the electron density near the extraction electrode was relatively high at 0.276. The measured electron temperature showed the existence of high-energy electrons in the sheet plasma. The extracted negative hydrogen current density of 0963-0252/5/3/009/img4 is higher than what has been obtained from similar sources. The bulk electron temperature and density at the centre of the sheet plasma were measured to be 11.06 eV and 0963-0252/5/3/009/img5, respectively.

  20. Plasma Compression in Magnetic Reconnection Regions in the Solar Corona

    NASA Astrophysics Data System (ADS)

    Provornikova, E.; Laming, J. M.; Lukin, V. S.

    2016-07-01

    It has been proposed that particles bouncing between magnetized flows converging in a reconnection region can be accelerated by the first-order Fermi mechanism. Analytical considerations of this mechanism have shown that the spectral index of accelerated particles is related to the total plasma compression within the reconnection region, similarly to the case of the diffusive shock acceleration mechanism. As a first step to investigate the efficiency of Fermi acceleration in reconnection regions in producing hard energy spectra of particles in the solar corona, we explore the degree of plasma compression that can be achieved at reconnection sites. In particular, we aim to determine the conditions for the strong compressions to form. Using a two-dimensional resistive MHD numerical model, we consider a set of magnetic field configurations where magnetic reconnection can occur, including a Harris current sheet, a force-free current sheet, and two merging flux ropes. Plasma parameters are taken to be characteristic of the solar corona. Numerical simulations show that strong plasma compressions (≥4) in the reconnection regions can form when the plasma heating due to reconnection is efficiently removed by fast thermal conduction or the radiative cooling process. The radiative cooling process that is negligible in the typical 1 MK corona can play an important role in the low corona/transition region. It is found that plasma compression is expected to be strongest in low-beta plasma β ˜ 0.01-0.07 at reconnection magnetic nulls.

  1. Magnetic Piston Propagation in a 100-ns Plasma Opening Switch

    NASA Astrophysics Data System (ADS)

    Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtman, A.

    1998-11-01

    The propagation of a magnetic piston through the plasma of a 90-ns, 170-kA POS is observed by studying the electron density, magnetic field, and ion velocity evolution. For the prefilled plasma n_e=(2.2± 0.5)× 10^14 cm-3, and T_e=5.5± 1 eV. The plasma composition is studied from absolute line intensities and collisional-radiative calculations. Most of the plasma ions are protons (90% near the cathode) with the rest being mainly CIV. The Hall-MHD conditions are not fulfilled for our experiment and ion motion is significant. The 3D-resolved ne evolution during the current pulse is studied from the line intensities of ions doped in the plasma using laser evaporation, and the magnetic field from Zeeman splitting. A diagonal magnetic piston propagates from the generator towards the load at about half the proton Alfven velocity. The protons are specularly reflected by the piston, while the heavy ions cross the potential hill in the piston, acquiring a lower velocity. The proton reflection causes an increase of ne ahead of the piston, followed by a sharp (10-20 ns) and substantial drop in ne (to 10-50% from the initial value). The magnetic field distribution studied using chordal observation, and theoretical analysis of ne and the magnetic field evolution are presented.

  2. Sustenance of inhomogeneous electron temperature in a magnetized plasma column

    SciTech Connect

    Karkari, S. K. Mishra, S. K.; Kaw, P. K.

    2015-09-15

    This paper presents the equilibrium properties of a magnetized plasma column sustained by direct-current (dc) operated hollow cathode discharge in conjunction with a conducting end-plate, acting as the anode. The survey of radial plasma characteristics, performed in argon plasma, shows hotter plasma in the periphery as compared to the central plasma region; whereas the plasma density peaks at the center. The off-centered peak in radial temperature is attributed due to inhomogeneous power deposition in the discharge volume in conjunction with short-circuiting effect by the conducting end plate. A theoretical model based on particle flux and energy balance is given to explain the observed characteristics of the plasma column.

  3. Passive Spectroscopic Diagnostics for Magnetically-confined Fusion Plasmas

    SciTech Connect

    Stratton, B. C.; Biter, M.; Hill, K. W.; Hillis, D. L.; Hogan, J. T.

    2007-07-18

    Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically-confined fusion plasmas, both in determining the effects of impurities on plasma behavior and in measurements of plasma parameters such as electron and ion temperatures and densities, particle transport, and particle influx rates. This paper reviews spectroscopic diagnostics of plasma radiation that are excited by collisional processes in the plasma, which are termed 'passive' spectroscopic diagnostics to distinguish them from 'active' spectroscopic diagnostics involving injected particle and laser beams. A brief overview of the ionization balance in hot plasmas and the relevant line and continuum radiation excitation mechanisms is given. Instrumentation in the soft X-ray, vacuum ultraviolet, ultraviolet, visible, and near-infrared regions of the spectrum is described and examples of measurements are given. Paths for further development of these measurements and issues for their implementation in a burning plasma environment are discussed.

  4. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2016-07-05

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  5. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2006-04-11

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  6. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2006-10-31

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  7. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2013-06-11

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  8. Thermo-galvanometric instabilities in magnetized plasma disks

    NASA Astrophysics Data System (ADS)

    Franco, Alessio; Montani, Giovanni; Carlevaro, Nakia

    2014-11-01

    In this work, we present a linear stability analysis of fully-ionized rotating plasma disks with a temperature gradient and a sub-thermal background magnetic field (oriented towards the axial direction). We describe how the plasma reacts when galvanometric and thermo-magnetic phenomena, such as Hall and Nernst-Ettingshausen effects, are taken into account, and meridian perturbations of the plasma are considered. It is shown how, in the ideal case, this leads to a significant overlap of the Magneto-rotational Instability and the Thermo-magnetic one. Considering dissipative effects, an overall damping of the unstable modes, although not sufficient to fully suppress the instability, appears especially in the thermo-magnetic related branch of the curve.

  9. Nonlinear magnetic field transport in opening switch plasmas

    NASA Astrophysics Data System (ADS)

    Mason, R. J.; Auer, P. L.; Sudan, R. N.; Oliver, B. V.; Seyler, C. E.; Greenly, J. B.

    1993-04-01

    The nonlinear transport of magnetic field in collisionless plasmas, as present in the plasma opening switch (POS), using the implicit multifluid simulation code anthem [J. Comput. Phys. 71, 429 (1987)] is studied. The focus is on early time behavior in the electron-magnetohydrodynamic (EMHD) limit, with the ions fixed, and the electrons streaming as a fluid under the influence of ve×B Hall forces. Through simulation, magnetic penetration and magnetic exclusion waves are characterized, due to the Hall effect in the presence of transverse density gradients, and the interaction of these Hall waves with nonlinear diffusive disturbances from electron velocity advection, (veṡ∇)ve, is studied. It is shown how these mechanisms give rise to the anode magnetic insulation layer, central diffusion, and cathode potential hill structures seen in earlier opening switch plasmas studies.

  10. Effect of magnetic and physical nozzles on plasma thruster performance

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazunori; Charles, Christine; Boswell, Rod; Ando, Akira

    2014-08-01

    Plasma cross-field diffusion in a magnetic nozzle is inhibited by increasing the magnetic field strength in a helicon plasma thruster attached to a pendulum thrust balance, while maintaining constant plasma density and electron temperature in the source tube, i.e. a constant plasma injection into the magnetic nozzle, where the field strength near the radio frequency (rf) antenna is less than 210 G and the operating argon pressure in the vacuum chamber is 0.8 mTorr. Inhibition of the cross-field diffusion yields a higher electron pressure in the magnetic nozzle and a resultant larger thrust. The thrust component arising from the magnetic nozzle approaches the theoretical limit derived from an ideal magnetic nozzle approximation where no plasma is lost from the nozzle and there is an azimuthal plasma current originating from the electron diamagnetic drift. It is also shown that the momentum of the plasma lost from the magnetic nozzle is captured by a physical nozzle attached at the source exit resulting in a larger thrust. Two physical nozzles of different sizes (nozzle 1 : 10.5 cm in length with a maximum diameter of 20 cm, nozzle 2 : 26 cm in length with a maximum diameter of 36 cm) are tested. The maximum thrust of 20 ± 1 mN is obtained for 25 sccm argon propellant and 2 kW rf power with a reflection power less than 5 W, which gives a specific impulse of 2750 ± 165 s and a thrust efficiency of 13.5 ± 1.5%.

  11. Effect of solenoidal magnetic field on drifting laser plasma

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazumasa; Okamura, Masahiro; Sekine, Megumi; Cushing, Eric; Jandovitz, Peter

    2013-04-01

    An ion source for accelerators requires to provide a stable waveform with a certain pulse length appropriate to the application. The pulse length of laser ion source is easy to control because it is expected to be proportional to plasma drifting distance. However, current density decay is proportional to the cube of the drifting distance, so large current loss will occur under unconfined drift. We investigated the stability and current decay of a Nd:YAG laser generated copper plasma confined by a solenoidal field using a Faraday cup to measure the current waveform. It was found that the plasma was unstable at certain magnetic field strengths, so a baffle was introduced to limit the plasma diameter at injection and improve the stability. Magnetic field, solenoid length, and plasma diameter were varied in order to find the conditions that minimize current decay and maximize stability.

  12. Collisionless Interaction of a Magnetized Ambient Plasma and a Field-Parallel Laser Produced Plasma

    NASA Astrophysics Data System (ADS)

    Heuer, P. V.; Bondarenko, A. S.; Schaeffer, D. B.; Constantin, C. G.; Vincena, S.; Tripathi, S.; Gekelman, W.; Weidl, M.; Winske, D.; Niemann, C.

    2016-10-01

    We present measurements of the collisionless coupling between an exploding laser-produced plasma (LPP) and a large, magnetized ambient plasma. The LPP was created by focusing the Raptor laser (400 J, 40 ns) on a planar plastic target embedded in the ambient Large Plasma Device (LAPD) plasma at the University of California, Los Angeles. The resulting ablated material moved parallel to the background magnetic field, interacting with the ambient plasma along the full 17m length of the LAPD. The amplitude and polarization of waves driven by the interaction were measured by an array of 3-axis magnetic flux probes. Emissive doppler spectroscopy and a high temporal resolution monochrometer were used to observe the velocity and charge state distributions of both ambient and debris ions. Measurements are compared to hybrid simulations of quasi-parallel shocks.

  13. Miniature Magnetized Shocks from Plasma Collision with Minimagnetospheres

    NASA Astrophysics Data System (ADS)

    Alves, E. P.; Cruz, F.; Bamford, R.; Bingham, R.; Fonseca, R.; Silva, L. O.

    2014-12-01

    Minimagnetospheres have been found to exist above the lunar surface, resulting from the solar wind plasma interaction with localized magnetic patches on the Moon's crust. The size of these objects are on the order of the plasma kinetic scales, lying beyond the validity of magnetohydrodynamics, and therefore constitute unique "laboratories" to investigate the role of kinetic effects in magnetosphere formation/dynamics. In this work we investigate the conditions under which collisionless magnetized shocks are formed due to plasma interaction with such small-scale (order of the plasma kinetic scales) magnetic obstacles. We have performed multidimensional particle-in-cell (PIC) simulations, that capture both electron and ion kinetics from first principles, in order to accurately describe the important microphysical processes associated with these scenarios. We observe the clear formation of a magnetized shock when the typical size of the magnetic obstacle is greater than ~ 2 ion-Larmor-radii. This condition may be fulfilled in lunar minimagnetospheres, whose dimensions are on the order of the ion inertial length, only for low Mach number shocks (<2). The effective size of the magnetic obstacle, however, is strongly dependent on the relative orientation of its own field to that of the plasma; antiparallel field configurations increase the effective size of the magnetic obstacle, allowing the clear formation of a shock, whereas in parallel field configurations the effective size of the magnetic obstacle is decreased, inhibiting shock formation in some cases. PIC simulations further capture electron-scale surface instabilities that modulate the magnetopause boundary and other streaming instabilities resulting from the interaction between the upstream and reflected plasma.

  14. Transport equations for partially ionized reactive plasma in magnetic field

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-06-01

    Transport equations for partially ionized reactive plasma in magnetic field taking into account the internal degrees of freedom and electronic excitation of plasma particles are derived. As a starting point of analysis the kinetic equation with a binary collision operator written in the Wang-Chang and Uhlenbeck form and with a reactive collision integral allowing for arbitrary chemical reactions is used. The linearized variant of Grad's moment method is applied to deduce the systems of moment equations for plasma and also full and reduced transport equations for plasma species nonequilibrium parameters.

  15. Collision-less Coupling between Explosive Debris Plasma and Magnetized Ambient Plasma

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton Sergeivich

    The explosive expansion of a dense debris plasma cloud into relatively tenuous, magnetized, ambient plasma characterizes a wide variety of astrophysical and space environments, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these and other related phenomena, collision-less electro-magnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris plasma to the ambient plasma. In an effort to better understand the detailed physics of collision-less coupling mechanisms, compliment in situ measurements, and provide validation of previous computational and theoretical work, the present research utilizes a unique experimental platform at the University of California, Los Angeles (UCLA) to study the interaction of explosive debris plasma with magnetized ambient plasma in a reproducible laboratory setting. Specifically, by jointly employing the Large Plasma Device (LAPD) and the Phoenix laser facility, the super-Alfvenic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma is investigated via a variety of sophisticated diagnostics, including emission spectroscopy, wavelength-filtered imaging, a magnetic flux probe, and a Langmuir probe. The key result is the direct observation of collision-less coupling via large Doppler shifts in a He II ion spectral line, which indicate that the ambient ions accelerate in response to the explosive debris plasma. Specifically, the He II ions accelerate along a trajectory that qualitatively corresponds to the large-scale laminar electric field generated by the debris expansion. A custom computational approach is utilized to simulate the initial He II ion response to the explosive debris plasma, and a synthetic Doppler-shifted wavelength spectrum constructed from the simulated ion velocities excellently reproduces the experimental

  16. The Plasma Instrument for Magnetic Sounding (PIMS): Enabling Required Plasma Measurements for the Exploration of Europa

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; McNutt, R. L., Jr.; Kasper, J. C.; Case, A. W.; Rymer, A. M.; Khurana, K. K.; Stevens, M. L.; Jia, X.; Slavin, J. A.; Paty, C. S.; Smith, H. T.; Kivelson, M.; Saur, J.; Krupp, N.; Roussos, E.; Korth, H.

    2015-12-01

    Europa exists in a complicated plasma environment where the tilt of Jupiter's magnetic field and rapid rotation rate leads to a dynamic interaction with Europa's ionospheric plasma. While understanding this plasma interaction is interesting in its own right, it is crucial for successfully magnetically sounding Europa's subsurface ocean. . In magnetic sounding, currents induced in Europa by the changing Jovian plasma produce a detectable secondary magnetic field that reflects properties of Europa's subsurface ocean such as depth and conductivity. This technique was successfully employed with Galileo observations of Europa to demonstrate that Europa indeed has a subsurface ocean containing more liquid water than Earth's oceans. While these Galileo observations contributed to the renewed interest in Europa, the results raised major questions that remain unanswered, in part due to the large uncertainties in the ice shell thickness, ocean depth, and ocean salinity due to limitations in the observations. Here we present the scientific goals of the Plasma Instrument for Magnetic Sounding (PIMS), one of the 9 instruments selected for the Europa Multiple Flyby Mission. We specifically address how PIMS plasma measurements will transform the accuracy of magnetic sounding of Europa's subsurface oceans. We also present synergistic science with other Europa instrumentation such as the ultraviolet spectrometer, mass spectrometer, and the radar.

  17. Magnetic topology of a candidate NCSX plasma boundary configuration

    NASA Astrophysics Data System (ADS)

    Koniges, A. E.; Grossman, A.; Fenstermacher, M.; Kisslinger, J.; Mioduszewski, P.; Rognlien, T.; Strumberger, E.; Umansky, M.

    2003-02-01

    A candidate magnetic topology of the plasma boundary of the proposed compact stellarator national compact stellarator experiment (NCSX) is investigated using field-line tracing with diffusion. The required magnetic fields are obtained from a free-boundary equilibrium using the magnetic fields from external coils and bootstrap plasma currents inside the last closed magnetic surface (LCMS). These results are used to calculate the magnetic fields of the finite beta equilibria inside and outside the LCMS in a form suitable for field-line tracing. Poincaré plots of field lines that diffuse outwards from starting points just inside the LCMS indicate an ergodic divertor region. Intersections of field lines with a simple limiting surface show contained patches suitable for divertor control. Undesirable regions of sharply inclined angle of intersection with the limiting surface are localized, indicating the suitability of the configuration for optimized divertor design techniques. We also discuss physics implications of field-line lengths in the divertor region.

  18. Amplification of Collective Magnetic Fluctuations in Magnetized Bi-Maxwellian Plasmas for Parallel Wave Vectors. I. Electron-Proton Plasma

    NASA Astrophysics Data System (ADS)

    Vafin, S.; Schlickeiser, R.; Yoon, P. H.

    2016-09-01

    The general electromagnetic fluctuation theory is a powerful tool to analyze the magnetic fluctuation spectrum of a plasma. Recent works utilizing this theory for a magnetized non-relativistic isotropic Maxwellian electron-proton plasma have demonstrated that the equilibrium ratio of | δ B| /{B}0 can be as high as 10-12. This value results from the balance between spontaneous emission of fluctuations and their damping, and it is considerably smaller than the observed value | δ B| /{B}0 in the solar wind at 1 au, where {10}-3≲ | δ B| /{B}0≲ {10}-1. In the present manuscript, we consider an anisotropic bi-Maxwellian distribution function to investigate the effect of plasma instabilities on the magnetic field fluctuations. We demonstrate that these instabilities strongly amplify the magnetic field fluctuations and provide a sufficient mechanism to explain the observed value of | δ B| /{B}0 in the solar wind at 1 au.

  19. ICTP-IAEA Workshop on Dense Magnetized Plasma and Plasma Diagnostics: an executive summary

    NASA Astrophysics Data System (ADS)

    Gribkov, V. A.; Mank, G.; Markowicz, A.; Miklaszewski, R.; Tuniz, C.; Crespo, M. L.

    2011-12-01

    The Workshop on Dense Magnetized Plasma and Plasma Diagnostics was held from 15 to 26 November 2010 at the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy. It was attended by 60 participants, including 15 lecturers, 2 tutors and 37 trainees, representing 25 countries.

  20. Equilibrium and magnetic properties of a rotating plasma annulus

    SciTech Connect

    Wang Zhehui; Si Jiahe; Liu Wei; Li Hui

    2008-10-15

    Local linear analysis shows that magneto-rotational instability can be excited in laboratory rotating plasmas with a density of 10{sup 19} m{sup -3}, a temperature on the order of 10 eV, and a magnetic field on the order of 100 G. A laboratory plasma annulus experiment with a dimension of {approx}1 m, and rotation at {approx}0.5 sound speed is described. Correspondingly, magnetic Reynolds number of these plasmas is {approx}1000, and magnetic Prandtl number ranges from about one to a few hundred. A radial equilibrium, {rho}U{sub {theta}}{sup 2}/r=d(p+B{sub z}{sup 2}/2{mu}{sub 0})/dr=K{sub 0}, with K{sub 0} being a nonzero constant, is proposed for the experimental data. Plasma rotation is observed to drive a quasisteady diamagnetic electrical current (rotational current drive) in a high-{beta} plasma annulus. The rotational energy depends on the direction and the magnitude of the externally applied magnetic field. Radial current (J{sub r}) is produced through biasing the center rod at a negative electric potential relative to the outer wall. J{sub r}xB{sub z} torque generates and sustains the plasma rotation. Rotational current drive can reverse the direction of vacuum magnetic field, satisfying a necessary condition for self-generated closed magnetic flux surfaces inside plasmas. The Hall term is found to be substantial and therefore needs to be included in the Ohm's law for the plasmas. Azimuthal magnetic field (B{sub {theta}}) is found to be comparable with the externally applied vacuum magnetic field B{sub z}, and mainly caused by the electric current flowing in the center cylinder; thus, B{sub {theta}}{proportional_to}r{sup -1}. Magnetic fluctuations are anisotropic, radial-dependent, and contain many Fourier modes below the ion cyclotron frequency. Further theoretical analysis reflecting these observations is needed to interpret the magnetic fluctuations.

  1. Electromagnetic treatment of the multipole resonance probe

    NASA Astrophysics Data System (ADS)

    Lapke, Martin; Mussenbrock, Thomas; Brinkmann, Ralf Peter

    2009-10-01

    We present an electromagnetic model of the ``multipole resonance probe'' (MRP)-- a diagnostic concept which enables the simultaneous determination of plasma density, electron temperature, and collision rate in low-pressure gas discharges. The MRP is a radio-frequency driven probe of particular spherical design. In an idealized version the probe consists of two dielectrically shielded, conducting hemispheres. Driven by a radio-frequency source, the hemispheres are powered symmetrically. An analysis of the absorption spectrum shows a multitude of resonances, which allows for an analytical evaluation of the measured signal. The signal provides information on the distribution of the plasma in the probe's vicinity, from which the values of electron density, electron temperature and collision rate can be inferred. In this contribution the MRP will be modeled electromagnetically. Based on a comparision between full electromagnetic and electrostatic treatment, we show that a previously presented electrostatic treatment [1] was well justified.[4pt] [1] M.Lapke et al., Appl. Phys. Lett. 93, 051502 (2008)

  2. Transport Properties of Equilibrium Argon Plasma in a Magnetic Field

    SciTech Connect

    Bruno, D.; Laricchiuta, A.; Chikhaoui, A.; Kustova, E. V.; Giordano, D.

    2005-05-16

    Electron electrical conductivity coefficients of equilibrium Argon plasma in a magnetic field are calculated up to the 12th Chapman-Enskog approximation at pressure of 1 atm and 0.1 atm for temperatures 500K-20000K; the magnetic Hall parameter spans from 0.01 to 100. The collision integrals used in the calculations are discussed. The convergence properties of the different approximations are assessed. The degree of anisotropy introduced by the presence of the magnetic field is evaluated. Differences with the isotropic case can be very substantial. The biggest effects are visible at high ionization degrees, i.e. high temperatures, and at strong magnetic fields.

  3. The Effects of Magnetic Nozzle Configurations on Plasma Thrusters

    NASA Technical Reports Server (NTRS)

    Turchi, P. J.

    1997-01-01

    Over the course of eight years, the Ohio State University has performed research in support of electric propulsion development efforts at the NASA Lewis Research Center, Cleveland, OH. This research has been largely devoted to plasma propulsion systems including MagnetoPlasmaDynamic (MPD) thrusters with externally-applied, solenoidal magnetic fields, hollow cathodes, and Pulsed Plasma Microthrusters (PPT's). Both experimental and theoretical work has been performed, as documented in four master's theses, two doctoral dissertations, and numerous technical papers. The present document is the final report for the grant period 5 December 1987 to 31 December 1995, and summarizes all activities. Detailed discussions of each area of activity are provided in appendices: Appendix 1 - Experimental studies of magnetic nozzle effects on plasma thrusters; Appendix 2 - Numerical modeling of applied-field MPD thrusters; Appendix 3 - Theoretical and experimental studies of hollow cathodes; and Appendix 4 -Theoretical, numerical and experimental studies of pulsed plasma thrusters. Especially notable results include the efficacy of using a solenoidal magnetic field downstream of a plasma thruster to collimate the exhaust flow, the development of a new understanding of applied-field MPD thrusters (based on experimentally-validated results from state-of-the art, numerical simulation) leading to predictions of improved performance, an experimentally-validated, first-principles model for orificed, hollow-cathode behavior, and the first time-dependent, two-dimensional calculations of ablation-fed, pulsed plasma thrusters.

  4. Magnetic flux pileup and plasma depletion in Mercury's subsolar magnetosheath

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Slavin, James A.; Raines, Jim M.; Zurbuchen, Thomas H.; Anderson, Brian J.; Korth, Haje; Baker, Daniel N.; Solomon, Sean C.

    2013-11-01

    from the Fast Imaging Plasma Spectrometer (FIPS) and Magnetometer (MAG) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft during 40 orbits about Mercury are used to characterize the plasma depletion layer just exterior to the planet's dayside magnetopause. A plasma depletion layer forms at Mercury as a result of piled-up magnetic flux that is draped around the magnetosphere. The low average upstream Alfvénic Mach number (MA ~3-5) in the solar wind at Mercury often results in large-scale plasma depletion in the magnetosheath between the subsolar magnetopause and the bow shock. Flux pileup is observed to occur downstream under both quasi-perpendicular and quasi-parallel shock geometries for all orientations of the interplanetary magnetic field (IMF). Furthermore, little to no plasma depletion is seen during some periods with stable northward IMF. The consistently low value of plasma β, the ratio of plasma pressure to magnetic pressure, at the magnetopause associated with the low average upstream MA is believed to be the cause for the high average reconnection rate at Mercury, reported to be nearly 3 times that observed at Earth. Finally, a characteristic depletion length outward from the subsolar magnetopause of ~300 km is found for Mercury. This value scales among planetary bodies as the average standoff distance of the magnetopause.

  5. Effect of Magnetic Field Gradient on Plasma Detachment Induced by Breaking of Adiabatic Plasma Expansion

    NASA Astrophysics Data System (ADS)

    Chung, K. S.; Kim, June Young; Chung, Kyoung-Jae; Hwang, Y. S.

    2016-10-01

    A magnetic field gradient that is a variation in the magnetic field around the ion flow has been investigated as a primary parameter for ion detachment in the magnetic nozzle geometries. Some scale lengths of magnetic field are controlled by two solenoid coils outside the diffusion chamber of a ECR-driven linear plasma device. The axial and radial profiles of the plasma potential and electron temperature are measured by a Langmuir probe array for the various magnetic field configurations in the downstream. The local adiabaticity, strong constant magnetic moment, is satisfied with a linear relationship between the change in effective electron temperature and the change in plasma potential in the low magnetic field gradient. Whereas, with an increasing non-homogeneity of the magnetic field in the direction of the flow, the breaking of adiabatic plasma expansion is identified to measure the nonlinear process which is the variation for an adiabatic exponent. Such the loss of adiabaticity is also explained in terms of non-adiabaticity parameter i.e. degree of demagnetization. This research was supported by National R&D Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (Nos. 2014M1A7A1A02030165 and 2014M1A7A1A03045367).

  6. Multi-excitonic (N=1,2 and 3) quantum dots in magnetic field: Analytical mapping of correlations (exchange) by multipole expansion

    NASA Astrophysics Data System (ADS)

    Singh, Sunny; Kaur, Harsimran; Sharma, Shivalika; Aggarwal, Priyanka; Hazra, Ram Kuntal

    2017-04-01

    The understanding of the physics of exciton, bi-exciton, tri-exciton and the subsequent insight into controlling the properties of mesoscopic systems holds the key to various exotic optical, electrical and magnetic phenomena like superconductivity, Mott insulation, Quantum Hall effect etc. Many of exciton properties are similar to atomic hydrogen that attracts researchers to explore electronic structure of exciton in quantum dots, but nontriviality arises due to coulombic interactions among electrons and holes. We propose an exact integral of coulomb (exchange) correlation in terms of finitely summed Lauricella functions to examine 3-D exciton of harmonic dots confined in zero and non-zero arbitrary magnetic field. The highlight of our work is the use of exact variational solution for coloumbic interaction between the hole and the electron and evaluation of the cross terms arising out of the coupling among centre-of-mass and relative coordinates. We also have extended the size of the system to generalized N-body problem with N=3,4 for tri-exciton (e-e-h/e-h-h)

  7. Prospects for x-ray polarimetry measurements of magnetic fields in magnetized liner inertial fusion plasmas

    SciTech Connect

    Lynn, Alan G. Gilmore, Mark

    2014-11-15

    Magnetized Liner Inertial Fusion (MagLIF) experiments, where a metal liner is imploded to compress a magnetized seed plasma may generate peak magnetic fields ∼10{sup 4} T (100 Megagauss) over small volumes (∼10{sup −10}m{sup 3}) at high plasma densities (∼10{sup 28}m{sup −3}) on 100 ns time scales. Such conditions are extremely challenging to diagnose. We discuss the possibility of, and issues involved in, using polarimetry techniques at x-ray wavelengths to measure magnetic fields under these extreme conditions.

  8. Magnetic properties of Sm5Fe17/Fe composite magnets produced by spark plasma sintering method

    NASA Astrophysics Data System (ADS)

    Saito, Tetsuji; Miyoshi, Hiroya

    2012-04-01

    Mixtures of powdered Sm5Fe17 melt-spun ribbon and Fe powder were consolidated into bulk magnets by the spark plasma sintering (SPS) method. Although these bulk magnets consisted of the hard magnetic Sm5Fe17 and soft magnetic α-Fe phases, they had a smooth hysteresis loop and exhibited coercivity. Among the magnets studied, the Sm5Fe17/Fe composite magnet with 30%Fe showed a remanence of 94 emu/g with a coercivity of 2.9 kOe.

  9. Laboratory Experiments on Propagating Plasma Bubbles into Vacuum, Vacuum Magnetic Field, and Background Plasmas

    NASA Astrophysics Data System (ADS)

    Lynn, Alan G.; Zhang, Yue; Gilmore, Mark; Hsu, Scott

    2014-10-01

    We discuss the dynamics of plasma ``bubbles'' as they propagate through a variety of background media. These bubbles are formed by a pulsed coaxial gun with an externally applied magnetic field. Bubble parameters are typically ne ~1020 m-3, Te ~ 5 - 10 eV, and Ti ~ 10 - 15 eV. The structure of the bubbles can range from unmagnetized jet-like structures to spheromak-like structures with complex magnetic flux surfaces. Some of the background media the bubbles interact with are vacuum, vacuum with magnetic field, and other magnetized plasmas. These bubbles exhibit different qualitative behavior depending on coaxial gun parameters such as gas species, gun current, and gun bias magnetic field. Their behavior also depends on the parameters of the background they propagate through. Multi-frame fast camera imaging and magnetic probe data are used to characterize the bubble evolution under various conditions.

  10. Chaotic dynamics of coupled transverse-longitudinal plasma oscillations in magnetized plasmas.

    PubMed

    Teychenné, D; Bésuelle, E; Oloumi, A; Salomaa, R R

    2000-12-25

    The propagation of intense electromagnetic waves in cold magnetized plasma is tackled through a relativistic hydrodynamic approach. The analysis of coupled transverse-longitudinal plasma oscillations is performed for traveling plane waves. When these waves propagate perpendicularly to a static magnetic field, the model is describable in terms of a nonlinear dynamical system with 2 degrees of freedom. A constant of motion is obtained and the powerful classical mechanics methods can be used. A new class of solutions, i.e., the chaotic solutions, is discovered by the Poincaré surface of sections. As a result, coupled transverse-longitudinal plasma oscillations become aperiodically modulated.

  11. Collisionless Spectral Kinetic Simulation of Ideal Multipole Resonance Probe

    NASA Astrophysics Data System (ADS)

    Gong, Junbo; Wilczek, Sebastian; Szeremley, Daniel; Oberrath, Jens; Eremin, Denis; Dobrygin, Wladislaw; Schilling, Christian; Friedrichs, Michael; Brinkmann, Ralf Peter

    2016-09-01

    Active Plasma Resonance Spectroscopy denotes a class of industry-compatible plasma diagnostic methods which utilize the natural ability of plasmas to resonate on or near the electron plasma frequency ωpe. One particular realization of APRS with a high degree of geometric and electric symmetry is the Multipole Resonance Probe (MRP). The Ideal MRP(IMRP) is an even more symmetric idealization which is suited for theoretical investigations. In this work, a spectral kinetic scheme is presented to investigate the behavior of the IMRP in the low pressure regime. However, due to the velocity difference, electrons are treated as particles whereas ions are only considered as stationary background. In the scheme, the particle pusher integrates the equations of motion for the studied particles, the Poisson solver determines the electric field at each particle position. The proposed method overcomes the limitation of the cold plasma model and covers kinetic effects like collisionless damping.

  12. Magnetic Null Points in Kinetic Simulations of Space Plasmas

    NASA Astrophysics Data System (ADS)

    Olshevsky, Vyacheslav; Deca, Jan; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni

    2016-03-01

    We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind, and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3-9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their cross sections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

  13. Plasma transport in a simulated magnetic-divertor configuration

    SciTech Connect

    Strawitch, C. M.

    1981-03-01

    The transport properties of plasma on magnetic field lines that intersect a conducting plate are studied experimentally in the Wisconsin internal ring D.C. machine. The magnetic geometry is intended to simulate certain aspects of plasma phenomena that may take place in a tokamak divertor. It is found by a variety of measurements that the cross field transport is non-ambipolar; this may have important implications in heat loading considerations in tokamak divertors. The undesirable effects of nonambipolar flow make it preferable to be able to eliminate it. However, we find that though the non-ambipolarity may be reduced, it is difficult to eliminate entirely. The plasma flow velocity parallel to the magnetic field is found to be near the ion acoustic velocity in all cases. The experimental density and electron temperature profiles are compared to the solutions to a one dimensional transport model that is commonly used in divertor theory.

  14. Nonlinear Laser-Plasma Interaction in Magnetized Liner Inertial Fusion

    SciTech Connect

    Geissel, Matthias; Awe, Thomas James; Bliss, David E.; Campbell, Edward Michael; Gomez, Matthew R.; Harding, Eric; Harvey-Thompson, Adam James; Hansen, Stephanie B.; Jennings, Christopher Ashley; Kimmel, Mark W.; Knapp, Patrick; Lewis, Sean M.; McBride, Ryan D.; Peterson, Kyle; Schollmeier, Marius; Scoglietti, Daniel; Sefkow, Adam B.; Shores, Jonathon; Sinars, Daniel; Slutz, Stephen A.; Smith, Ian C.; Speas, Christopher; Vesey, Roger A.; Porter, John L.

    2016-03-04

    Sandia National Laboratories is pursuing a variation of Magneto-Inertial Fusion called Magnetized Liner Inertial Fusion, or MagLIF. The MagLIF approach requires magnetization of the deuterium fuel, which is accomplished by an initial external B-Field and laser-driven pre-heat. Although magnetization is crucial to the concept, it is challenging to couple sufficient energy to the fuel, since laser-plasma instabilities exist, and a compromise between laser spot size, laser entrance window thickness, and fuel density must be found. Ultimately, nonlinear processes in laser plasma interaction, or laser-plasma instabilities (LPI), complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray. We determine and discuss key LPI processes and mitigation methods. Results with and without improvement measures are presented.

  15. Self-Organizing Knotted Magnetic Structures in Plasma

    NASA Astrophysics Data System (ADS)

    Smiet, C. B.; Candelaresi, S.; Thompson, A.; Swearngin, J.; Dalhuisen, J. W.; Bouwmeester, D.

    2015-08-01

    We perform full-magnetohydrodynamics simulations on various initially helical configurations and show that they reconfigure into a state where the magnetic field lines span nested toroidal surfaces. This relaxed configuration is not a Taylor state, as is often assumed for relaxing plasma, but a state where the Lorentz force is balanced by the hydrostatic pressure, which is lowest on the central ring of the nested tori. Furthermore, the structure is characterized by a spatially slowly varying rotational transform, which leads to the formation of a few magnetic islands at rational surfaces. We then obtain analytic expressions that approximate the global structure of the quasistable linked and knotted plasma configurations that emerge, using maps from S3 to S2 of which the Hopf fibration is a special case. The knotted plasma configurations have a highly localized magnetic energy density and retain their structure on time scales much longer than the Alfvénic time scale.

  16. Electrodeless RF Plasma Propulsion by Rotating Magnetic Field Method

    NASA Astrophysics Data System (ADS)

    Furukawa, Takerku; Takizawa, Kohei; Kuwahara, Daisuke; Shinohara, Shunjiro

    2016-10-01

    Electric propulsion scheme is promising in the field of the space propulsion because of high fuel efficiency and long operating time. However, this time is limited due to the loss of electrodes contacting with plasmas directly. In order to solve this problem, we have proposed electrodeless acceleration schemes, e.g., a rotating magnetic field (RMF) scheme. In this RMF scheme, we use two pairs of 5 turns RMF coils with AC currents, which have a 90 deg. phase difference. The rotating magnetic field induces azimuthal current j by a nonlinear effect. Then, plasma is accelerated by the axial Lorentz force using the product of j and the radial component of external magnetic field. We have investigated the effect of the RMF current frequency f, and 24% increase of ion velocity in the case of f = 3 MHz. We will present the experimental results, using lower f and gas pressure, and also discuss the penetration of RMF into the plasma.

  17. Nonlinear Laser-Plasma Interaction in Magnetized Liner Inertial Fusion

    DOE PAGES

    Geissel, Matthias; Awe, Thomas James; Bliss, David E.; ...

    2016-03-04

    Sandia National Laboratories is pursuing a variation of Magneto-Inertial Fusion called Magnetized Liner Inertial Fusion, or MagLIF. The MagLIF approach requires magnetization of the deuterium fuel, which is accomplished by an initial external B-Field and laser-driven pre-heat. Although magnetization is crucial to the concept, it is challenging to couple sufficient energy to the fuel, since laser-plasma instabilities exist, and a compromise between laser spot size, laser entrance window thickness, and fuel density must be found. Ultimately, nonlinear processes in laser plasma interaction, or laser-plasma instabilities (LPI), complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray. Wemore » determine and discuss key LPI processes and mitigation methods. Results with and without improvement measures are presented.« less

  18. The magnetic mirror force in plasma fluid models

    NASA Technical Reports Server (NTRS)

    Comfort, R. H.

    1988-01-01

    In the past decade, there have been several attempts to include the magnetic mirror force in the equation of motion for a plasma in a fluid formalism. In the process, some confusion has been evident regarding when and how this should be done. This problem has been addressed in the literature, but these treatments appear to have been forgotten or misunderstood. The mathematical arguments are summarized so that the physical consequences are readily perceived. It is shown that for an isotropic plasma fluid, in the direction parallel or anti-parallel to a magnetic field, the forces associated with a diverging magnetic field cancel out. Only for anisotropies in the fluid properties does the diverging field influence the plasma dynamics.

  19. Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma.

    PubMed

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M; Myers, Clayton E

    2014-09-10

    Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first time in a well-defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step towards resolving one of the most important problems in plasma physics.

  20. Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma

    SciTech Connect

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; Ji, Hantao; Kulsrud, Russell M.; Myers, Clayton E.

    2014-09-10

    Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first time in a well defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step toward resolving one of the most important problems in plasma physics.

  1. Conversion of magnetic energy in the magnetic reconnection layer of a laboratory plasma

    DOE PAGES

    Yamada, Masaaki; Yoo, Jongsoo; Jara-Almonte, Jonathan; ...

    2014-09-10

    Magnetic reconnection, in which magnetic field lines break and reconnect to change their topology, occurs throughout the universe. The essential feature of reconnection is that it energizes plasma particles by converting magnetic energy. Despite the long history of reconnection research, how this energy conversion occurs remains a major unresolved problem in plasma physics. Here we report that the energy conversion in a laboratory reconnection layer occurs in a much larger region than previously considered. The mechanisms for energizing plasma particles in the reconnection layer are identified, and a quantitative inventory of the converted energy is presented for the first timemore » in a well defined reconnection layer; 50% of the magnetic energy is converted to particle energy, 2/3 of which transferred to ions and 1/3 to electrons. Our results are compared with simulations and space measurements, for a key step toward resolving one of the most important problems in plasma physics.« less

  2. Performance improvement of magnetized coaxial plasma gun by magnetic circuit on a bias coil

    NASA Astrophysics Data System (ADS)

    Edo, Takahiro; Matsumoto, Tadafumi; Asai, Tomohiko; Kamino, Yasuhiro; Inomoto, Michiaki; Gota, Hiroshi

    2016-10-01

    A magnetized coaxial plasmoid accelerator has been utilized for compact torus (CT) injection to refuel into fusion reactor core plasma. Recently, CT injection experiments have been conducted on the C-2/C-2U facility at Tri Alpha Energy. In the series of experiments successful refueling, i.e. increased particle inventory of field-reversed configuration (FRC) plasma, has been observed. In order to improve the performance of CT injector and to refuel in the upgraded FRC device, called C-2W, with higher confinement magnetic field, magnetic circuit consisting of magnetic material onto a bias magnetic coil is currently being tested at Nihon University. Numerical work suggests that the optimized bias magnetic field distribution realizes the increased injection velocity because of higher conversion efficiency of Lorenz self force to kinetic energy. Details of the magnetic circuit design as well as results of the test experiment and field calculations will be presented and discussed.

  3. Dusty Plasmas in Planetary Magnetospheres Award

    NASA Technical Reports Server (NTRS)

    Horanyi, Mihaly

    2005-01-01

    This is my final report for the grant Dusty Plasmas in Planetary Magnetospheres. The funding from this grant supported our research on dusty plasmas to study: a) dust plasma interactions in general plasma environments, and b) dusty plasma processes in planetary magnetospheres (Earth, Jupiter and Saturn). We have developed a general purpose transport code in order to follow the spatial and temporal evolution of dust density distributions in magnetized plasma environments. The code allows the central body to be represented by a multipole expansion of its gravitational and magnetic fields. The density and the temperature of the possibly many-component plasma environment can be pre-defined as a function of coordinates and, if necessary, the time as well. The code simultaneously integrates the equations of motion with the equations describing the charging processes. The charging currents are dependent not only on the instantaneous plasma parameters but on the velocity, as well as on the previous charging history of the dust grains.

  4. Magnetized and collimated millimeter scale plasma jets with astrophysical relevance

    SciTech Connect

    Brady, Parrish C.; Quevedo, Hernan J.; Valanju, Prashant M.; Bengtson, Roger D.; Ditmire, Todd

    2012-01-15

    Magnetized collimated plasma jets are created in the laboratory to extend our understanding of plasma jet acceleration and collimation mechanisms with particular connection to astrophysical jets. In this study, plasma collimated jets are formed from supersonic unmagnetized flows, mimicking a stellar wind, subject to currents and magnetohydrodynamic forces. It is found that an external poloidal magnetic field, like the ones found anchored to accretion disks, is essential to stabilize the jets against current-driven instabilities. The maximum jet length before instabilities develop is proportional to the field strength and the length threshold agrees well with Kruskal-Shafranov theory. The plasma evolution is modeled qualitatively using MHD theory of current-carrying flux tubes showing that jet acceleration and collimation arise as a result of electromagnetic forces.

  5. Experimental Characterization of Plasma Detachment from Magnetic Nozzles

    NASA Astrophysics Data System (ADS)

    Olsen, Christopher Scott

    Magnetic nozzles, like Laval nozzles, are observed in several natural systems and have application in areas such as electric propulsion and plasma processing. Plasma flowing through these nozzles is inherently tied to the field lines and must separate for momentum redirection or particle transport to occur. Plasma detachment and associated mechanisms from a magnetic nozzle are investigated. Experimental results are presented from the plume of the VASIMRRTM VX-200 device flowing along an axisymmetric magnetic nozzle and operated at two ion energies to explore momentum dependent detachment. The argon plume expanded into a 150m3 vacuum chamber where the background pressure was low enough that charge-exchange mean-free-paths were longer than experiment scale lengths. This magnetic nozzle system is demonstrated to hydrodynamically scale up to astrophysical plasmas, particularly the solar chromosphere, implying general relevance to many systems. Plasma parameters were mapped over a large spatial range using measurements from multiple plasma diagnostics. The data show that the plume does not follow the magnetic field lines. A mapped integration of the ion flux shows the plume may be divided into three regions where 1) the plume briefly follows the magnetic flux, 2) diverges quadratically before 3) expanding with linear trajectories. Transitioning from region 1→2, the ion flux departs from the magnetic flux suggesting ion detachment. An instability forms in region 2 driving an oscillating electric field that causes ions to expand before enhancing electron cross-field transport through anomalous resistivity. Transitioning from region 2→3 the electric field dissipates, the trajectories linearize, and the plume effectively detaches. A delineation of sub-to-super Alfvenic flow aligns well with the inflection points of the linearization without a change in magnetic topology. The detachment process is best described as a two part process: First, ions detach by a breakdown of

  6. Mirror-field confined compact plasma source using permanent magnet for plasma processings

    NASA Astrophysics Data System (ADS)

    Goto, Tetsuya; Sato, Kei-ichiro; Yabuta, Yuki; Sugawa, Shigetoshi

    2016-12-01

    A mirror-field confined compact electron cyclotron resonance (ECR) plasma source using permanent magnets was developed, aiming for the realization of high-quality plasma processings where high-density reactive species are supplied to a substrate with minimizing the ion bombardment damages. The ECR position was located between a microwave transmissive window and a quartz limiter, and plasmas were transported from the ECR position to a midplane of the magnetic mirror field through the quartz limiter. Thus, a radius of core plasma could be determined by the limiter, which was 15 mm in this study. Plasma parameters were investigated by the Langmuir probe measurement. High-density plasma larger than 1011 cm-3 could be produced by applying 5.85-GHz microwave power of 10 W or more. For the outside region of the core plasma where a wafer for plasma processings will be set at, the ion current density was decreased dramatically with distance from the core plasma and became smaller by approximately two orders of magnitude that in the core plasma region for the radial position of 40 mm, suggesting the realization of reduction in ion bombardment damages.

  7. Mirror-field confined compact plasma source using permanent magnet for plasma processings.

    PubMed

    Goto, Tetsuya; Sato, Kei-Ichiro; Yabuta, Yuki; Sugawa, Shigetoshi

    2016-12-01

    A mirror-field confined compact electron cyclotron resonance (ECR) plasma source using permanent magnets was developed, aiming for the realization of high-quality plasma processings where high-density reactive species are supplied to a substrate with minimizing the ion bombardment damages. The ECR position was located between a microwave transmissive window and a quartz limiter, and plasmas were transported from the ECR position to a midplane of the magnetic mirror field through the quartz limiter. Thus, a radius of core plasma could be determined by the limiter, which was 15 mm in this study. Plasma parameters were investigated by the Langmuir probe measurement. High-density plasma larger than 10(11) cm(-3) could be produced by applying 5.85-GHz microwave power of 10 W or more. For the outside region of the core plasma where a wafer for plasma processings will be set at, the ion current density was decreased dramatically with distance from the core plasma and became smaller by approximately two orders of magnitude that in the core plasma region for the radial position of 40 mm, suggesting the realization of reduction in ion bombardment damages.

  8. Conservation of magnetic helicity during plasma relaxation

    SciTech Connect

    Ji, H.; Prager, S.C.; Sarff, J.S.

    1994-07-01

    Decay of the total magnetic helicity during the sawtooth relaxation in the MST Reversed-Field Pinch is much larger than the MHD prediction. However, the helicity decay (3--4%) is smaller than the magnetic energy decay (7--9%), modestly supportive of the helicity conservation hypothesis in Taylor`s relaxation theory. Enhanced fluctuation-induced helicity transport during the relaxation is observed.

  9. Magnetic reconnection in a compressible MHD plasma

    SciTech Connect

    Hesse, Michael; Zenitani, Seiji; Birn, Joachim

    2011-04-15

    Using steady-state resistive MHD, magnetic reconnection is reinvestigated for conditions of high resistivity/low magnetic Reynolds number, when the thickness of the diffusion region is no longer small compared to its length. Implicit expressions for the reconnection rate and other reconnection parameters are derived based on the requirements of mass, momentum, and energy conservation. These expressions are solved via simple iterative procedures. Implications specifically for low Reynolds number/high resistivity are being discussed.

  10. Magnetic Reconnection in a Compressible MHD Plasma

    NASA Technical Reports Server (NTRS)

    Hesse, Michael; Birn, Joachim; Zenitani, Seiji

    2011-01-01

    Using steady-state resistive MHD, magnetic reconnection is reinvestigated for conditions of high resistivity/low magnetic Reynolds number, when the thickness of the diffusion region is no longer small compared to its length. Implicit expressions for the reconnection rate and other reconnection parameters are derived based on the requirements of mass, momentum, and energy conservation. These expressions are solved via simple iterative procedures. Implications specifically for low Reynolds number/high resistivity are being discussed

  11. Magnetized plasma flow injection into tokamak and high-beta compact torus plasmas

    NASA Astrophysics Data System (ADS)

    Matsunaga, Hiroyuki; Komoriya, Yuuki; Tazawa, Hiroyasu; Asai, Tomohiko; Takahashi, Tsutomu; Steinhauer, Loren; Itagaki, Hirotomo; Onchi, Takumi; Hirose, Akira

    2010-11-01

    As an application of a magnetized coaxial plasma gun (MCPG), magnetic helicity injection via injection of a highly elongated compact torus (magnetized plasma flow: MPF) has been conducted on both tokamak and field-reversed configuration (FRC) plasmas. The injected plasmoid has significant amounts of helicity and particle contents and has been proposed as a fueling and a current drive method for various torus systems. In the FRC, MPF is expected to generate partially spherical tokamak like FRC equilibrium by injecting a significant amount of magnetic helicity. As a circumstantial evidence of the modified equilibrium, suppressed rotational instability with toroidal mode number n = 2. MPF injection experiments have also been applied to the STOR-M tokamak as a start-up and current drive method. Differences in the responses of targets especially relation with beta value and the self-organization feature will be studied.

  12. Nonlinear magnetic field transport in opening switch plasmas

    SciTech Connect

    Mason, R.J. ); Auer, P.L.; Sudan, R.N.; Oliver, B.V.; Seyler, C.E.; Greenly, J.B. )

    1993-04-01

    The nonlinear transport of magnetic field in collisionless plasmas, as present in the plasma opening switch (POS), using the implicit multifluid simulation code ANTHEM [J. Comput. Phys. [bold 71], 429 (1987)] is studied. The focus is on early time behavior in the electron--magnetohydrodynamic (EMHD) limit, with the ions fixed, and the electrons streaming as a fluid under the influence of [bold v][sub [ital e

  13. Mass production of magnetic nickel nanoparticle in thermal plasma reactor

    SciTech Connect

    Kanhe, Nilesh S.; Nawale, Ashok B.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

    2014-04-24

    We report the mass production of Ni metal nanoparticles using dc transferred arc thermal plasma reactor by homogeneous gas phase condensation process. To increase the evaporation rate and purity of Ni nanoparticles small amount of hydrogen added along with argon in the plasma. Crystal structure analysis was done by using X-ray diffraction technique. The morphology of as synthesized nanoparticles was carried out using FESEM images. The magnetic properties were measured by using vibrating sample magnetometer at room temperature.

  14. Theoretical model of fishbone oscillations in magnetically confined plasmas

    SciTech Connect

    Coppi, B.; Porcelli, F.

    1986-11-03

    The onset of electromagnetic oscillations that are observed in magnetically confined plasmas where beams of fast neutrals are injected is associated with the excitation of a mode with poloidal wave number m/sup 0/ = 1 and phase velocity equal to the core-ion diamagnetic velocity. The resonant interaction of the mode with the beam ions is viewed as a form of dissipation that allows the release of the mode excitation energy, related to the gradient of the plasma pressure.

  15. Slot-Antenna/Permanent-Magnet Device for Generating Plasma

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    A device that includes a rectangular-waveguide/slot-antenna structure and permanent magnets has been devised as a means of generating a substantially uniform plasma over a relatively large area, using relatively low input power and a low gas flow rate. The device utilizes electron cyclotron resonance (ECR) excited by microwave power to efficiently generate plasma in a manner that is completely electrodeless in the sense that, in principle, there is no electrical contact between the plasma and the antenna. Plasmas generated by devices like this one are suitable for use as sources of ions and/or electrons for diverse material-processing applications (e.g., etching or deposition) and for ion thrusters. The absence of plasma/electrode contact essentially prevents plasma-induced erosion of the antenna, thereby also helping to minimize contamination of the plasma and of objects exposed to the plasma. Consequently, the operational lifetime of the rectangular-waveguide/ slot-antenna structure is long and the lifetime of the plasma source is limited by the lifetime of the associated charged-particle-extraction grid (if used) or the lifetime of the microwave power source. The device includes a series of matched radiating slot pairs that are distributed along the length of a plasma-source discharge chamber (see figure). This arrangement enables the production of plasma in a distributed fashion, thereby giving rise to a uniform plasma profile. A uniform plasma profile is necessary for uniformity in any electron- or ion-extraction electrostatic optics. The slotted configuration of the waveguide/ antenna structure makes the device scalable to larger areas and higher powers. All that is needed for scaling up is the attachment of additional matched radiating slots along the length of the discharge chamber. If it is desired to make the power per slot remain constant in scaling up, then the input microwave power must be increased accordingly. Unlike in prior ECR microwave plasma

  16. The effects of magnetic nozzle configurations on plasma thrusters

    NASA Technical Reports Server (NTRS)

    York, Thomas M.

    1989-01-01

    Plasma thrusters have been operated at power levels from 10kW to 0.1MW. When these devices have had magnetic fields applied to them which form a nozzle configuration for the expanding plasma, they have shown marked increases in exhaust velocity which is in direct proportion to the magnitude of the applied field. Further, recent results have shown that electrode erosion may be influenced by applied magnetic fields. This research is directed to the experimental and computational study of the effects of applied magnetic field nozzles in the acceleration of plasma flows. Plasma source devices which eliminate the plasma interaction in normal thrusters are studied as most basic. Normal thruster configurations will be studied without applied fields and with applied magnetic nozzle fields. Unique computational studies will utilize existing codes which accurately include transport processes. Unique diagnostic studies will support the experimental studies to generate new data. Both computation and diagnostics will be combined to indicate the physical mechanisms and transport properties that are operative in order to allow scaling and accurate prediction of thruster performance.

  17. Plasma Detachment Studies in the VASIMR Magnetic Nozzle

    NASA Astrophysics Data System (ADS)

    Tarditi, Alfonso G.; Shebalin, John

    2004-11-01

    Two important issues related to the VASIMR (Variable Specific Impulse Magnetoplasma Rocket, [1]) experiment are the plasma detachment and the collimation of the plume in the magnetic nozzle. These issues are being investigated both through theory/simulation studies and now also experimentally. A 3D, nonlinear MHD/2-fluid model of the magnetic nozzle has been implemented with the NIMROD code. The model has been run both with the actual VASIMR geometry and for an ideal De Laval nozzle configuration. The simulations indicate a distortion of the external field due to the plasma exhaust flow (carrying an azimuthal diamagnetic current) that may to lead to plasma detachment through the formation of magnetic islands. This is also being investigated experimentally. A Hall-effect, one-axis, gaussmeter has shown the local low-frequency magnetic field fluctuations during a plasma pulse. A 2D array of 3-axis "B-dot" probes is being developed for a fast mapping of the field perturbations in the nozzle (on the order of the Alfven time). Finally, a Rogowski coil probe is being designed to measure the azimuthal current profile in the exhaust plasma. [1] F. R. Chang-Diaz et al, Scientific American, p. 90, Nov. 2000

  18. Magnetic Fluctuation-Driven Intrinsic Flow in a Toroidal Plasma

    NASA Astrophysics Data System (ADS)

    Brower, D. L.; Ding, W. X.; Lin, L.; Almagri, A. F.; den Hartog, D. J.; Sarff, J. S.

    2012-10-01

    Magnetic fluctuations have been long observed in various magnetic confinement configurations. These perturbations may arise naturally from plasma instabilities such as tearing modes and energetic particle driven modes, but they can also be externally imposed by error fields or external magnetic coils. It is commonly observed that large MHD modes lead to plasma locking (no rotation) due to torque produced by eddy currents on the wall, and it is predicted that stochastic field induces flow damping where the radial electric field is reduced. Flow generation is of great importance to fusion plasma research, especially low-torque devices like ITER, as it can act to improve performance. Here we describe new measurements in the MST reversed field pinch (RFP) showing that the coherent interaction of magnetic and particle density fluctuations can produce a turbulent fluctuation-induced kinetic force, which acts to drive intrinsic plasma rotation. Key observations include; (1) the average kinetic force resulting from density fluctuations, ˜ 0.5 N/m^3, is comparable to the intrinsic flow acceleration, and (2) between sawtooth crashes, the spatial distribution of the kinetic force is directed to create a sheared parallel flow profile that is consistent with the measured flow profile in direction and amplitude, suggesting the kinetic force is responsible for intrinsic plasma rotation.

  19. The plasma drag and dust motion inside the magnetized sheath

    SciTech Connect

    Pandey, B. P.; Vladimirov, S. V.; Samarian, A.

    2011-05-15

    The motion of micron size dust inside the sheath in the presence of an oblique magnetic field is investigated by self-consistently calculating the charge and various forces acting on the dust. It is shown that the dust trajectory inside the sheath, which is like an Archimedean spiral swinging back and forth between the wall and the plasma-sheath boundary, depends only indirectly on the orientation of the magnetic field. When the Lorentz force is smaller than the collisional momentum exchange, the dust dynamics is insensitive to the obliqueness of the magnetic field. Only when the magnetic field is strong enough, the sheath structure and, thus, the dust dynamics are significantly affected by the field orientation. Balance between the plasma drag, sheath electrostatic field, and gravity plays an important role in determining how far the dust can travel inside the sheath. The dust equilibrium point shifts closer to the wall in the presence of gravity and plasma drag. However, in the absence of plasma drag, dust can sneak back into the plasma if acted only by gravity. The implication of our results to the usability of dust as a sheath probe is discussed.

  20. Viscosity and Shear Flows in Magnetized Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Romero-Talamas, C. A.; Bates, E. M.; Birmingham, W. J.; Rivera, W. F.; Takeno, J.; Knop, S.

    2015-11-01

    Magnetized dusty plasma experiments are planned at the Dusty Plasma Laboratory of the University of Maryland, Baltimore County (UMBC), to investigate E x B rotation with dust of at least 500 nm in diameter. At this size, individual particles can be tracked and viscosity, shear flow, and temperature can be measured directly using a methodology similar to that used for linear shear flow configurations [Feng et al. PRL 109, 185002 (2012)]. The experiments are planned with a specially designed Bitter-type magnet that can be configured to achieve up to 10 T for at least 10 seconds, to minutes, with much longer operation times at lower fields also possible. At the highest field, the dust will be fully magnetized and thus we aim to achieve direct E x B rotation of the dust (and not just by ion drag). The motivation for these experiments comes from observations of electron and ion temperatures in excess of 100 eV in E x B rotating plasmas [R. Reid et al. Phys. Plasmas 21, 063305 (2014)]. The experimental setup and planned diagnostics for the magnetized dusty plasma are presented.

  1. Alfvénic tornadoes in a magnetized plasma

    NASA Astrophysics Data System (ADS)

    Shukla, P. K.

    2013-01-01

    It is shown that three-dimensional (3D) modified-kinetic Alfvén waves (m-KAWs) in a magnetized plasma can propagate in the form of Alfvénic tornadoes characterized by plasma density whirls or magnetic flux ropes carrying orbital angular momentum. By using the two-fluid model, together with Ampère's law, we derive the wave equation for 3D m-KAWs in a magnetoplasma with me/mi ≪ β ≪ 1, where me (mi) is the electron (ion) mass, β=4πn0kB (Te+Ti)/B02, n0 the unperturbed plasma number density, kB the Boltzmann constant, Te(Te) the electron (ion) temperature, and B0 the strength of the ambient magnetic field. The 3D m-KAW equation admits solutions in the form of a Laguerre-Gauss Alfvénic vortex beam or a twisted kinetic Alfvénic wave with plasma density whirls that support the dynamics of shear Alfvénic magnetic flux ropes in plasmas.

  2. The effects of magnetic nozzle configurations on plasma thrusters

    NASA Technical Reports Server (NTRS)

    York, Thomas M.

    1990-01-01

    Plasma thrusters have been operated at power levels from 10 kw to 0.1 MW. When these devices have had magnetic fields applied to them which form a nozzle configuration for the expanding plasma, they have shown marked increases in exhaust velocity which is in direct proportion to the magnitude of the applied field. Further, recent results have shown that electrode erosion may be influenced by applied magnetic fields. This research effort is directed to the experimental and computational study of the effects of applied magnetic field nozzles in the acceleration of plasma flows. Plasma source devices which eliminate the plasma interaction in normal thrusters are studied as most basic. Normal thruster configurations were studied without applied fields and with applied magnetic nozzle fields. Unique computational studies utilize existing codes which accurately include transport processes. Unique diagnostic studies supported the experimental studies to generate new data. Both computation and diagnostics were combined to indicate the physical mechanisms and transport properties that are operative in order to allow scaling and accurate prediction of thruster performance.

  3. Oblique ion acoustic shock waves in a magnetized plasma

    SciTech Connect

    Shahmansouri, M.; Mamun, A. A.

    2013-08-15

    Ion acoustic (IA) shock waves are studied in a magnetized plasma consisting of a cold viscous ion fluid and Maxwellian electrons. The Korteweg–de Vries–Burgers equation is derived by using the reductive perturbation method. It is shown that the combined effects of external magnetic field and obliqueness significantly modify the basic properties (viz., amplitude, width, speed, etc.) of the IA shock waves. It is observed that the ion-viscosity is a source of dissipation, and is responsible for the formation of IA shock structures. The implications of our results in some space and laboratory plasma situations are discussed.

  4. 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

  5. Magnetic configuration of the distant plasma sheet - ISEE 3 observations

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.; Smith, E. J.; Daly, P. W.; Sanderson, T. R.; Wenzel, K.-P.; Lepping, R. P.

    1987-01-01

    The influence of the IMF orientation and magnitude and substorm activity on the magnetic configuration of the central plasma sheet at 20-240 earth radii down the geomagnetic tail is investigated on the basis of ISEE-3 data. The results are presented graphically, and high-speed antisolar bulk flows threaded by southward magnetic fields are shown to be present in the distant plasma sheet after periods of substorm activity and southward IMF Bz. The effective dayside reconnection efficiency is estimated as 25 + or - 4 percent, in good agreement with theoretical models.

  6. Simulation study of the magnetized sheath of a dusty plasma

    SciTech Connect

    Foroutan, G.; Mehdipour, H.; Zahed, H.

    2009-10-15

    Numerical solutions of stationary multifluid equations are used to study the formation and properties of the magnetized sheath near the boundary of a dusty plasma. The impacts of the strength of the magnetic field, the dust and plasma number densities, and the electron temperature on the sheath structure and spatial distributions of various quantities are investigated. It is shown that for a given angle of incidence of the magnetic field, there is a threshold magnetic field intensity above which some kind of large regular inhomogeneities develop on the spatial profile of the dust particles. The sheath thickness, the electron and ion number densities, and the absolute dust charge are strongly affected by the variation in the dust number density. The sheath demonstrates a nonlinear dependence on the electron temperature; as the electron temperature rises, the sheath first is broadened and the absolute wall potential decreases but then at higher temperatures the sheath becomes narrower and the absolute wall potential increases.

  7. The resistance peak of helicon plasmas at low magnetic fields

    SciTech Connect

    Cho, Suwon

    2006-03-15

    The dispersion characteristics of the radial eigenmodes and resistive loading of helicon plasmas are studied to explain the occurrence of the density peak at low magnetic fields. The plasma resistance is usually found to be large for the eigenmodes near the magnetic field where the fast and slow waves are coupled and can be peaked at low magnetic fields depending on the antenna configuration. It is explained how reflection of the waves at an axial end causes the resistance peak at low magnetic fields for a single loop antenna and the Nagoya type III or helical antenna itself can give rise to the resistance peak regardless of reflection. Finally, the dependence of the resistance peak on the density and the wave frequency is examined to show that the general trend is consistent with experimental observations.

  8. Dynamics of resonant magnetic field penetration and plasma rotation

    NASA Astrophysics Data System (ADS)

    Ivanov, N. V.; Kakurin, A. M.

    2017-01-01

    Results of calculations and analysis of the penetration of resonant magnetic perturbations (RMP) into tokamak plasma are presented. The TEAR code used for the calculations is based on a two-fluid magnetohydrodynamics approximation that gives coupled diffusion-type equations for the magnetic flux perturbation and for plasma rotation velocities in toroidal and poloidal directions. The radial distribution of the magnetic flux perturbation is calculated taking account of an externally applied RMP and magnetic perturbation generated by an eddy current in the resistive-vacuum vessel. The decoupling of magnetic-island velocity from the velocity of plasma rotation is employed in the calculations according to available experimental evidence and corresponding theoretical understanding. The account of this decoupling, as well as of plasma rotation in the poloidal direction in addition to the toroidal one, reduces the RMP penetration threshold and accelerates the penetration process. The main attention is paid to the dependences of the RMP penetration dynamics on the simulation conditions. The simulation findings are compared with available experimental data. Some predictions of the penetration threshold values for ITER conditions are presented.

  9. ASYMMETRIC MAGNETIC RECONNECTION IN WEAKLY IONIZED CHROMOSPHERIC PLASMAS

    SciTech Connect

    Murphy, Nicholas A.; Lukin, Vyacheslav S.

    2015-06-01

    Realistic models of magnetic reconnection in the solar chromosphere must take into account that the plasma is partially ionized and that plasma conditions within any two magnetic flux bundles undergoing reconnection may not be the same. Asymmetric reconnection in the chromosphere may occur when newly emerged flux interacts with pre-existing, overlying flux. We present 2.5D simulations of asymmetric reconnection in weakly ionized, reacting plasmas where the magnetic field strengths, ion and neutral densities, and temperatures are different in each upstream region. The plasma and neutral components are evolved separately to allow non-equilibrium ionization. As in previous simulations of chromospheric reconnection, the current sheet thins to the scale of the neutral–ion mean free path and the ion and neutral outflows are strongly coupled. However, the ion and neutral inflows are asymmetrically decoupled. In cases with magnetic asymmetry, a net flow of neutrals through the current sheet from the weak-field (high-density) upstream region into the strong-field upstream region results from a neutral pressure gradient. Consequently, neutrals dragged along with the outflow are more likely to originate from the weak-field region. The Hall effect leads to the development of a characteristic quadrupole magnetic field modified by asymmetry, but the X-point geometry expected during Hall reconnection does not occur. All simulations show the development of plasmoids after an initial laminar phase.

  10. Polarization-Sensitive Measurements Of Magnetic Fields In Magnetized Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, Showera; Wallace, Matthew S.; Neill, Paul; Presura, Radu

    2016-10-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult in this regime because the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Using an idea proposed by Tessarin et al. (2011), we have measured the field in magnetized laser plasmas and in the current-driven exploding wire plasmas. Time-gated spectra with one-dimensional space-resolution were obtained at the Nevada Terawatt Facility for laser plasmas created by 20 J, 1 ns Leopard laser pulses, and expanding in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator, and for wire array plasmas driven by the 1 MA configuration of the Zebra generator. We explore the response of the Al III 4s 2S1/2- 4p 2P1 / 2 , 3 / 2 doublet components to the external magnetic field spatially along the plasma in two orthogonal polarizations. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength was measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES Grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  11. Measurement Of Magnetic Fields In Magnetized Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, Showera; Wallace, Matthew S.; Neill, Paul; Presura, Radu

    2015-11-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult in this regime because the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Using an idea proposed by Tessarin et al. (2011), we have measured the field in magnetized laser plasmas and the magnetized precursor of wire array z-pinches. Time-gated spectra with one-dimensional space-resolution were obtained at the Nevada Terawatt Facility for laser plasmas created by 20 J, 1 ns Leopard laser pulses, and expanding in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator, and for wire array plasmas driven by the 1 MA configuration of the Zebra generator. We explore the response of the Al III 4s 2S1/2- 4p 2P1 / 2 , 3 / 2 doublet components and the C IV 3s 2S1/2- 3p 2P1 / 2 , 3 / 2 doublet components to the external magnetic field spatially along the plasma. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength was measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  12. Neutral Vlasov kinetic theory of magnetized plasmas

    SciTech Connect

    Tronci, Cesare; Camporeale, Enrico

    2015-02-15

    The low-frequency limit of Maxwell equations is considered in the Maxwell-Vlasov system. This limit produces a neutral Vlasov system that captures essential features of plasma dynamics, while neglecting radiation effects. Euler-Poincaré reduction theory is used to show that the neutral Vlasov kinetic theory possesses a variational formulation in both Lagrangian and Eulerian coordinates. By construction, the new model recovers all collisionless neutral models employed in plasma simulations. Then, comparisons between the neutral Vlasov system and hybrid kinetic-fluid models are presented in the linear regime.

  13. Thermal magnetic fluctuations of whistlers in a Maxwellian plasma

    NASA Technical Reports Server (NTRS)

    Golubyatnikov, G.; Stenzel, R. L.

    1993-01-01

    Thermal fluctuations were measured with a magnetic-loop antenna inside a large afterglow plasma in the whistler-wave regime. The magnetic fluctuations exhibit a 1/f-like spectrum for whistlers, no resonant enhancement at the electron cyclotron frequency, and a flat spectrum in the evanescent regime. The observed fluctuations are therefore described neither by blackbody radiation laws nor by cyclotron emission, but resemble the decaying Alfvenic fluctuations spectrum calculated by Cable and Tajima (1992).

  14. Magnetic field measurements for study of fast electron transport in magnetized HED plasma

    NASA Astrophysics Data System (ADS)

    Sawada, Hiroshi; Griffin, Brandon; Presura, Radu; Haque, Showera; Sentoku, Yasuhiko

    2014-10-01

    Interaction of megagauss magnetic fields with high energy density (HED) plasma is of great interest in the field of magnetized plasma. The field changes fundamental properties of the HED plasma such as thermal and magnetic diffusion. A coupled capability utilizing the 1.0 MA Zebra pulsed power generator and the 50 TW Leopard laser at Nevada Terawatt Facility enables to create such a condition for studies of magnetized plasma properties. We have conducted an experiment to measure magnetic fields generated by a 1.0 MA, 100 ns Zebra pulsed current in stainless steel coils. Using a 532 nm continuous laser from a single longitudinal mode laser system, the temporal change in the magnetic field was measured with the Faraday rotation in F2 glass. The probe laser passing through the 1.5 mm in radius and 1.75 mm thick glass placed in the vicinity of the inductive coils was split with a Glan-Taylor prism to measure vertical and horizontal polarization components with photodiodes. We will present the analysis of the experimental result and a design of a coupled experiment for study of fast electron transport in the magnetized plasma.

  15. Vlasov-Fokker-Planck modeling of magnetized plasma

    SciTech Connect

    Thomas, Alexander

    2016-08-01

    Understanding the magnetic fields that can develop in high-power-laser interactions with solid-density plasma is important because such fields significantly modify both the magnitude and direction of electron heat fluxes. The dynamics of such fields evidently have consequences for inertial fusion energy applications, as the coupling of the laser beams with the walls or pellet and the development of temperature inhomogeneities are critical to the uniformity of the implosion and potentially the success of, for example, the National Ignition Facility. To study these effects, we used the code Impacta, a two-dimensional, fully implicit, Vlasov-Fokker-Planck code with self-consistent magnetic fields and a hydrodynamic ion model, designed for nanosecond time-scale laser-plasma interactions. Heat-flux effects in Ohm’s law under non-local conditions was investigated; physics that is not well captured by standard numerical models but is nevertheless important in fusion-related scenarios. Under such conditions there are numerous interesting physical effects, such as collisional magnetic instabilities, amplification of magnetic fields, re-emergence of non-locality through magnetic convection, and reconnection of magnetic field lines and redistribution of thermal energy. In this project highlights included the first full scale kinetic simulations of a magnetized hohlraum [Joglekar 2016] and the discovery of a new magnetic reconnection mechanism [Joglekar 2014] as well as a completed PhD thesis and the production of a new code for Inertial Fusion research.

  16. Anode plasma density measurements in a magnetically insulated diode

    SciTech Connect

    Pal, R.; Hammer, D.

    1983-03-07

    The surface-flashover anode plasma in a magnetically insulated ion diode was investigated spectroscopically. From the Stark broadening of the neutral hydrogen H/sub ..beta../ line an average electron density of about 2 x 10/sup 15//cm/sup 3/ was observed in the < or approx. =1-mm anode plasma, 30 nsec into the 400--475-kV diode voltage pulse. Thereafter, the plasma front advanced into the diode gap at an average rate of 2 cm/..mu..sec. This may be explained by the ionization of neutral atoms injected into the gap during flashover.

  17. Stark broadening of hydrogen lines in magnetic fusion plasmas

    NASA Astrophysics Data System (ADS)

    Rosato, J.; Godbert-Mouret, L.; Koubiti, M.; Marandet, Y.; Stamm, R.

    2017-03-01

    We report on a Stark line shape model for the diagnostic of tokamak edge plasmas. In specific scenarios, plasma discharges are carried out at high density regimes, sufficiently so that the spectral lines emitted by the neutral atoms present in the edge and in the divertor region are affected by the plasma microscopic electric field (Stark broadening). We present new line shape calculations, carried out for diagnostic purposes in the context of the MST1 (Medium Sized Tokamak) European campaign. The role of the magnetic field (Zeeman effect) on line spectra is discussed.

  18. Practicality of magnetic compression for plasma density control

    SciTech Connect

    Gueroult, Renaud; Fisch, Nathaniel J.

    2016-03-16

    Here, plasma densification through magnetic compression has been suggested for time-resolved control of the wave properties in plasma-based accelerators [P. F. Schmit and N. J. Fisch, Phys. Rev. Lett. 109, 255003 (2012)]. Using particle in cell simulations with real mass ratio, the practicality of large magnetic compression on timescales shorter than the ion gyro-period is investigated. For compression times shorter than the transit time of a compressional Alfven wave across the plasma slab, results show the formation of two counter-propagating shock waves, leading to a highly non-uniform plasma density profile. Furthermore, the plasma slab displays large hydromagnetic like oscillations after the driving field has reached steady state. Peak compression is obtained when the two shocks collide in the mid-plane. At this instant, very large plasma heating is observed, and the plasmaβ is estimated to be about 1. Although these results point out a densification mechanism quite different and more complex than initially envisioned, these features still might be advantageous in particle accelerators.

  19. Atoms and plasmas in a high-magnetic-field trap

    SciTech Connect

    Raithel, G.; Knuffman, B.; Shah, M. H.; Hempel, C.; Paradis, E.; Mhaskar, R.; Zhang, X.; Choi, J.-H.; Povilus, A. P.; Guest, J. R.

    2008-08-08

    We investigate cold rubidium plasmas in a particle trap that has the unique capability to simultaneously laser-cool and trap neutral atoms as well as to confine plasmas in magnetic fields of about three Tesla. The atom trap is a high-field Ioffe-Pritchard laser trap, while the plasma trap is a Ioffe-Penning trap that traps electrons and ions in separate wells. The observed plasma dynamics is characterized by a breathing-mode oscillation of the positive (ionic) plasma component, which feeds back on the behavior of the negative (electron) component of the plasma. At higher densities, the observed oscillations become nonlinear. The electron component has been found to undergo rapid cooling. We further report on the recombination of magnetized plasmas into Rydberg atoms in transient traps and quasi-steady-state traps. In transient traps, large numbers of recombined Rydberg atoms in high-lying states are observed. In quasi-steady-state traps, the measured numbers of recombined atoms are lower and the binding energies higher.

  20. Antenna impedance measurements in a magnetized plasma. I. Spherical antenna

    SciTech Connect

    Blackwell, David D.; Walker, David N.; Messer, Sarah J.; Amatucci, William E.

    2007-09-15

    The input impedance of a metal sphere immersed in a magnetized plasma is measured with a network analyzer at frequencies up to 1 GHz. The experiments were done in the Space Physics Simulation Chamber at the Naval Research Laboratory. The hot-filament argon plasma was varied between weakly ({omega}{sub ce}<{omega}{sub pe}) and strongly ({omega}{sub ce}>{omega}{sub pe}) magnetized plasma with electron densities in the range 10{sup 7}-10{sup 10} cm{sup -3}. It is observed that the lower-frequency resonance of the impedance characteristic previously associated with series sheath resonance {omega}{sub sh} in the unmagnetized plasma occurs at a hybrid sheath frequency of {omega}{sub r}{sup 2}={omega}{sub sh}{sup 2}+{kappa}{omega}{sub ce}{sup 2}, where {kappa} is a constant 0.5<{kappa}<1. As seen in previous experiments, the higher frequency resonance associated with the electron plasma frequency {omega}{sub pe} in the unmagnetized plasma is relocated to the upper hybrid frequency {omega}{sub uh}{sup 2}={omega}{sub pe}{sup 2}+{omega}{sub ce}{sup 2}. As with the unmagnetized plasma, the maximum power deposition occurs at the lower frequency resonance {omega}{sub r}.

  1. Non-axisymmetric magnetic fields and toroidal plasma confinement

    NASA Astrophysics Data System (ADS)

    Boozer, Allen H.

    2015-02-01

    The physics of non-axisymmetry is a far more important topic in the theory of toroidal fusion plasmas than might be expected. (1) Even a small toroidal asymmetry in the magnetic field strength, δ ≡ ∂ln B/∂φ ˜ 10-4, can cause an unacceptable degradation in performance. (2) Nevertheless, asymmetries—even large asymmetries δ ˜ 1—can give beneficial plasma control and circumvent issues, such as magnetic-configuration maintenance and plasma disruptions, that make axisymmetric fusion devices problematic. Viewed from prospectives that are adequate for designing and studying axisymmetric plasmas, the physics of non-axisymmetric plasmas appears dauntingly difficult. Remarkably, Maxwell's equations provide such strong constraints on the physics of toroidal fusion plasmas that even a black-box model of a plasma answers many important questions. Kinetic theory and non-equilibrium thermodynamics provide further, but more nuanced, constraints. This paper is organized so these constraints can be used as a basis for the innovations and for the extrapolations that are required to go from existing experiments to fusion systems. Outlines are given of a number of calculations that would be of great importance to ITER and to the overall fusion program and that could be carried out now with limited resources.

  2. Practicality of magnetic compression for plasma density control

    DOE PAGES

    Gueroult, Renaud; Fisch, Nathaniel J.

    2016-03-16

    Here, plasma densification through magnetic compression has been suggested for time-resolved control of the wave properties in plasma-based accelerators [P. F. Schmit and N. J. Fisch, Phys. Rev. Lett. 109, 255003 (2012)]. Using particle in cell simulations with real mass ratio, the practicality of large magnetic compression on timescales shorter than the ion gyro-period is investigated. For compression times shorter than the transit time of a compressional Alfven wave across the plasma slab, results show the formation of two counter-propagating shock waves, leading to a highly non-uniform plasma density profile. Furthermore, the plasma slab displays large hydromagnetic like oscillations aftermore » the driving field has reached steady state. Peak compression is obtained when the two shocks collide in the mid-plane. At this instant, very large plasma heating is observed, and the plasmaβ is estimated to be about 1. Although these results point out a densification mechanism quite different and more complex than initially envisioned, these features still might be advantageous in particle accelerators.« less

  3. A multi-model plasma simulation of collisionless magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Datta, I. A. M.; Shumlak, U.; Ho, A.; Miller, S. T.

    2016-10-01

    Collisionless magnetic reconnection is a process relevant to many areas of plasma physics in which energy stored in magnetic fields within highly conductive plasmas is rapidly converted to plasma energy. A full understanding of this phenomenon, however, is currently incomplete as models developed to date have difficulty explaining the fast reconnection rates often seen in nature, such as in the case of solar flares. Therefore, this behavior represents an area of much research in which various plasma models have been tested in order to understand the proper physics explaining the reconnection process. In this research, the WARPXM code developed at the University of Washington is used to study the problem using a hybrid multi-model simulation employing Hall-MHD and two-fluid plasma models. The simulation is performed on a decomposed domain where different plasma models are solved in different regions, depending on a trade-off between each model's physical accuracy and associated computational expense in each region. The code employs a discontinuous Galerkin (DG) finite element spatial discretization coupled with a Runge-Kutta scheme for time advancement and uses boundary conditions to couple the different plasma models. This work is supported by a Grant from the United States Air Force Office of Scientific Research.

  4. Plasma flows and fluctuations with magnetic islands in the edge plasmas of J-TEXT tokamak

    NASA Astrophysics Data System (ADS)

    Zhao, K. J.; Shi, Y. J.; Hahn, S. H.; Diamond, P. H.; Sun, Y.; Cheng, J.; Liu, H.; Lie, N.; Chen, Z. P.; Ding, Y. H.; Chen, Z. Y.; Rao, B.; Leconte, M.; Bak, J. G.; Cheng, Z. F.; Gao, L.; Zhang, X. Q.; Yang, Z. J.; Wang, N. C.; Wang, L.; Jin, W.; Yan, L. W.; Dong, J. Q.; Zhuang, G.; J-TEXT Team

    2015-07-01

    The first comprehensive measurements of plasma flows and fluctuations nearby static magnetic islands driven by resonant magnetic perturbations are presented. These experiments were performed using multiple Langmuir probe arrays on the edge plasmas of the J-TEXT tokamak. Controlled variations of the island size and location are explored. This study aims to understand the interaction between turbulence and magnetic islands, and to elucidate magnetic island effects on edge turbulence and flow intensity profiles, edge electric fields, and thus confinement regime transitions. Turbulence and low frequency flows (LFFs) all drop inside the magnetic island, but increase at its boundary, as island width increases. The geodesic acoustic mode is damped in most of the edge area with magnetic islands. The sign of the radial electric field changes from negative to positive within the islands. The gradient of turbulent stresses vanishes at the island center, and becomes steeper at the boundaries of the islands. The particle transport induced by the turbulence is reduced inside the magnetic islands. The magnetic island effects on flows and turbulence can lead to an increase in LFFs and enhance Reynolds stresses near the last closed flux surface (LCFS). A stronger radial electric field layer can be formed near the LCFS when magnetic islands are present. The results suggest that magnetic islands can be used as a tool to enhance edge turbulence and flows, edge electric fields, and thus to trigger confinement regime transitions.

  5. Magnetic reconnection in a magnetohydrodynamic plasma

    SciTech Connect

    Kulsrud, R.M.

    1998-05-01

    Magnetic reconnection is important because of its connection with the topology of field lines. In general, a change in topology means a change of equilibrium, and a release of energy, such as occurs in solar flares. In the context of the solar flare two models for magnetic reconnection, the Sweet{endash}Parker and the Petschek mechanism are presented. The pros and cons of these two models are presented. The role of anomalous resistivity in the Sweet{endash}Parker model is discussed. The bearing of a laboratory experiment and a boundary layer analysis of the problem are described. {copyright} {ital 1998 American Institute of Physics.}

  6. Collision-less Coupling between Explosive Debris Plasmas and Magnetized Background Plasmas

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Schaeffer, Derek; Clark, S. Eric; Everson, Erik; Lee, Bo Ram; Constantin, Carmen; Niemann, Christoph

    2015-11-01

    The explosive expansion of debris plasma into magnetized background plasma characterizes a variety of astrophysical and space environments, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these and other related phenomena, collision-less electro-magnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris to the background. A unique experiment that jointly utilizes the Large Plasma Device (LAPD) and the Phoenix laser facility at UCLA has investigated the super-Alfvénic, quasi-perpendicular expansion of a laser-produced carbon (C) debris plasma through a preformed, magnetized helium (He) background plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and magnetic field probes. Collision-less coupling is directly observed via Doppler shifts in the He II 468.6 nm spectral line, which indicate that the He II ions are accelerated by the laminar electric field that develops due to the expanding C debris. By utilizing an early-time model of the C debris density and velocity, the laminar electric field is calculated and used in combination with the measured magnetic field to simulate He II ion trajectories and velocities. A synthetic Doppler-shifted wavelength spectrum of the He II 468.6 nm spectral line is generated from the simulated He II ion velocities and found to agree well with the measurements.

  7. Interaction of gravitational waves with strongly magnetized plasmas

    SciTech Connect

    Isliker, Heinz; Vlahos, Loukas; Sandberg, Ingmar

    2006-11-15

    We study the interaction of a gravitational wave (GW) with a plasma that is strongly magnetized. The GW is considered a small disturbance, and the plasma is modeled by the general relativistic analogue of the induction equation of ideal MHD and the single fluid equations. The equations are specified to two different cases, first to Cartesian coordinates and a constant background magnetic fields, and second to spherical coordinates together with a background magnetic field that decays with the inverse radial distance. The equations are derived without neglecting any of the nonlinear interaction terms, and the nonlinear equations are integrated numerically. We find that for strong magnetic fields of the order of 10{sup 15} G the GW excites electromagnetic plasma waves very close to the magnetosonic mode. The magnetic and electric field oscillations have very high amplitude, and a large amount of energy is absorbed from the GW by the electromagnetic oscillations, of the order of 10{sup 23} erg/cm{sup 3} in the case presented here, which, when assuming a relatively small volume in a star's magnetosphere as an interaction region, can yield a total energy of at least 10{sup 41} erg and may be up to 10{sup 43} erg. The absorbed energy is proportional to B{sub 0}{sup 2}, with B{sub 0} the background magnetic field. The energizing of the plasma takes place on fast time scales of the order of milliseconds. Our results imply that the GW-plasma interaction is an efficient and important mechanism in magnetar atmospheres, most prominently close to the star, and, under very favorable conditions though, it might even be the primary energizing mechanism behind giant flares.

  8. Plane and hemispherical potential structures in magnetically expanding plasmas

    SciTech Connect

    Takahashi, Kazunori; Igarashi, Yuichi; Fujiwara, Tamiya

    2010-07-26

    Two-dimensional potential structures are measured for different gas pressure in expanding argon plasma using permanent magnets, where the magnetic field is about 100 G in the source and several gauss in the diffusion chamber. The plane potential drop is observed near the source exit for 0.35 mTorr, while the potential structure becomes hemispherical when increasing up to 1 mTorr; the hemispherical structure results in the radial divergence of the ion beam. It is found that the trajectories of the accelerated ions and the electrons overcoming the potential drop are dominated by the potential structure and magnetic-field lines, respectively.

  9. Microseconds-scale magnetic actuators system for plasma feedback stabilization

    NASA Astrophysics Data System (ADS)

    Kogan, K.; Be'ery, I.; Seemann, O.

    2016-10-01

    Many magnetic confinement machines use active feedback stabilization with magnetic actuators. We present a novel magnetic actuators system with a response time much faster than previous ones, making it capable of coping with the fast plasma instabilities. The system achieved a response time of 3 μs with maximal current of 500 A in a coil with inductance of 5.2 μH. The system is based on commercial solid-state switches and FPGA state machine, making it easily scalable to higher currents or higher inductivity.

  10. Injection of a coaxial-gun-produced magnetized plasma into a background helicon plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott

    2014-10-01

    A compact coaxial plasma gun is employed for experimental investigation of plasma bubble relaxation into a lower density background plasma. Experiments are being conducted in the linear device HelCat at UNM. The gun is powered by a 120-uF ignitron-switched capacitor bank, which is operated in a range of 5 to 10 kV and 100 kA. Multiple diagnostics are employed to investigate the plasma relaxation process. Magnetized argon plasma bubbles with velocities 1.2Cs, densities 1020 m-3 and electron temperature 13eV have been achieved. The background helicon plasma has density 1013 m-3, magnetic field from 200 to 500 Gauss and electron temperature 1eV. Several distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. Additionally a B-dot probe array has been employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify plasma bubble configurations. Experimental data and analysis will be presented.

  11. Studies of HED Plasmas with Self-Generated Magnetic Field

    SciTech Connect

    Medvedev, Mikhail

    2016-02-08

    High-amplitude sub-Larmor-scale electromagnetic turbulence is ubiquitous in high-energy density environments, such as laboratory plasmas produced by high-intensity lasers, e.g., NIF, Omega-EP, Trident, and others, and in astrophysical and space plasmas, e.g., at high-Mach-number collisionless shocks in weakly magnetized plasmas upstream regions of quasi-parallel shocks, sites of magnetic reconnection and others. Studies of plasmas and turbulence in these environments are important for fusion energy sciences and the inertial confinement concept, in particular, as well as to numerous astrophysical systems such as gamma-ray bursts, supernovae blast waves, jets of quasars and active galactic nuclei, shocks in the interplanetary medium, solar flares and many more. Such turbulence can be of various origin and thus have rather different properties, from being purely magnetic (Weibel) turbulence to various types of electromagnetic turbulence (for example, whistler wave turbulence or turbulence produced by filamentation or Weibel-type streaming instability), to purely electrostatic Langmuir turbulence. In this project we use analytical and numerical tools to study the transport, radiative, and magneto-optical properties of plasmas with sub-Larmor-scale turbulence. We discovered the connection of transport/diffusion properties to certain spectral benchmark features of (jitter) radiation produced by the plasma and radiation propagation through it. All regimes, from the relativistic to non-relativistic, were thoroughly investigated and predictions were made for laboratory plasmas and astrophysical plasmas. Thus, all the tasks outlined in the proposal were fully and successfully accomplished.

  12. Planar Multipol-Resonance-Probe: A Spectral Kinetic Approach

    NASA Astrophysics Data System (ADS)

    Friedrichs, Michael; Gong, Junbo; Brinkmann, Ralf Peter; Oberrath, Jens; Wilczek, Sebastian

    2016-09-01

    Measuring plasma parameters, e.g. electron density and electron temperature, is an important procedure to verify the stability and behavior of a plasma process. For this purpose the multipole resonance probe (MRP) represents a satisfying solution to measure the electron density. However the influence of the probe on the plasma through its physical presence makes it unattractive for some processes in industrial application. A solution to combine the benefits of the spherical MRP with the ability to integrate the probe into the plasma reactor is introduced by the planar model of the MRP (pMRP). Introducing the spectral kinetic formalism leads to a reduced simulation-circle compared to particle-in-cell simulations. The model of the pMRP is implemented and first simulation results are presented.

  13. Magnetic plasma confinement for laser ion source.

    PubMed

    Okamura, M; Adeyemi, A; Kanesue, T; Tamura, J; Kondo, K; Dabrowski, R

    2010-02-01

    A laser ion source (LIS) can easily provide a high current beam. However, it has been difficult to obtain a longer beam pulse while keeping a high current. On occasion, longer beam pulses are required by certain applications. For example, more than 10 micros of beam pulse is required for injecting highly charged beams to a large sized synchrotron. To extend beam pulse width, a solenoid field was applied at the drift space of the LIS at Brookhaven National Laboratory. The solenoid field suppressed the diverging angle of the expanding plasma and the beam pulse was widened. Also, it was observed that the plasma state was conserved after passing through a few hundred gauss of the 480 mm length solenoid field.

  14. Ideal plasma response to vacuum magnetic fields with resonant magnetic perturbations in non-axisymmetric tokamaks

    DOE PAGES

    Kim, Kimin; Ahn, J. -W.; Scotti, F.; ...

    2015-09-03

    Ideal plasma shielding and amplification of resonant magnetic perturbations in non-axisymmetric tokamak is presented by field line tracing simulation with full ideal plasma response, compared to measurements of divertor lobe structures. Magnetic field line tracing simulations in NSTX with toroidal non-axisymmetry indicate the ideal plasma response can significantly shield/amplify and phase shift the vacuum resonant magnetic perturbations. Ideal plasma shielding for n = 3 mode is found to prevent magnetic islands from opening as consistently shown in the field line connection length profile and magnetic footprints on the divertor target. It is also found that the ideal plasma shielding modifiesmore » the degree of stochasticity but does not change the overall helical lobe structures of the vacuum field for n = 3. Furthermore, amplification of vacuum fields by the ideal plasma response is predicted for low toroidal mode n = 1, better reproducing measurements of strong striation of the field lines on the divertor plate in NSTX.« less

  15. Interaction of Electromagnetic Fields with Magnetized Plasmas

    DTIC Science & Technology

    1994-03-31

    operation. 9 These inventories were the result verted by an energy conversion system with efficiency of about a year of full- power operation at 1 GW of i... power with an efficiency ii,. Recirculating sion or D-T fusion reactor, once operated in space, is power required for purposes other than plasma heating...Z "( = LAPRPSMA:= "HATN FUSION GROSS PNET (a HANGPOWER EFFICIENCY , GOSPE SYSTEM POE FIINY ELECTRICAL EFFICIENCY , PF n POWER Pw - PG THERMAL WASTE PR

  16. Effect of the plasma-induced magnetic field on a magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Merino, Mario; Ahedo, Eduardo

    2016-08-01

    A two-fluid, two-dimensional model of the plasma expansion in a divergent magnetic nozzle is used to investigate the effect of the plasma-induced magnetic field on the acceleration and divergence of the plasma jet self-consistently. The induced field is diamagnetic and opposes the applied one, increasing the divergence of the magnetic nozzle and weakening its strength. This has a direct impact on the propulsive performance of the device, the demagnetization and detachment of the plasma, and can lead to the appearance of zero-field points and separatrix surfaces downstream. In contrast, the azimuthal induced field, albeit non-zero, is small in all cases of practical interest.

  17. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    SciTech Connect

    Haynes, Christopher T. Burgess, David; Sundberg, Torbjorn; Camporeale, Enrico

    2015-01-15

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  18. Magnetic Diagnostics at the Wisconsin Plasma Astrophysics Laboratory

    NASA Astrophysics Data System (ADS)

    Peterson, Ethan; Clark, Michael; Egedal, Jan; Wallace, John; Weisberg, David; Forest, Cary

    2015-11-01

    A flexible suite of magnetic diagnostics is being developed to measure low and high frequency magnetic fields, the 3-D magnetic field structure throughout the plasma volume, and the 2-D structure (polar and azimuthal fields) on the surface of the sphere. The internal 3-D structure is ascertained by scanning insertion probes with high sensitivity, high bandwidth, 3-axis hall effect sensors. Careful engineering of these insertion probes is required to effectively remove the heat load while simultaneously maintaining high performance (hot, dense, steady state) plasmas. A surface array of 3-axis hall-effect sensors and 2-axis flux loops will provide 3-D, low frequency magnetic field measurements as well as high frequency fluctuations in the polar and azimuthal directions due to plasma waves. This surface array can be used to observe the spatial structure of global modes such as spherical ion acoustic waves and can provide insight into the structure and magnitude of internal plasma flows. The engineering and capabilities of these diagnostics is the focus of this poster.

  19. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    NASA Astrophysics Data System (ADS)

    Haynes, Christopher T.; Burgess, David; Camporeale, Enrico; Sundberg, Torbjorn

    2015-01-01

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  20. Plasma flow, turbulence and magnetic islands in TJ-II

    NASA Astrophysics Data System (ADS)

    Estrada, T.; Ascasíbar, E.; Blanco, E.; Cappa, A.; Hidalgo, C.; Ida, K.; López-Fraguas, A.; van Milligen, B. Ph

    2016-02-01

    The effect of magnetic islands on plasma flow and turbulence has been experimentally investigated in ohmically induced magnetic configuration scans at the stellarator TJ-II. This operational mode allows sweeping the radial position of a low order rational surface from the plasma core towards the edge in a controlled way, what reveals effects that are difficult to notice in scans performed on a shot to shot basis. The main diagnostic used in the present work is a two-channel Doppler reflectometer that allows the measurement of the perpendicular rotation velocity of the turbulence and density fluctuations with good spatial and temporal resolution. A characteristic signature of the n/m  =  3/2 magnetic island as it crosses the measurement position is clearly detected: the perpendicular flow reverses at the center of the magnetic island and a flow shear develops at the island boundaries. Fluctuations of the perpendicular flow and density have been also measured along the 3/2 magnetic island. An increase in the low frequency flow oscillations is measured at the magnetic island boundaries together with a reduction in the density fluctuation level; the later being more pronounced at the inner island boundary. These observations could explain the link between magnetic islands and transport barriers observed in a number of fusion devices.

  1. Performance characterization of a permanent-magnet helicon plasma thruster

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazunori; Charles, Christine; Boswell, Rod

    2012-10-01

    Helicon plasma thrusters operated at a few kWs of rf power is an active area of an international research. Recent experiments have clarified part of the thrust-generation mechanisms. Thrust components which have been identified include an electron pressure inside the source region and a Lorentz force due to an electron diamagnetic drift current and a radial component of the applied magnetic field. The use of permanent magnets (PMs) instead of solenoids is one of the solutions for improving the thruster efficiency because it does not require electricity for the magnetic nozzle formation. Here the thrust imparted from a permanent-magnet helicon plasma thruster is directly measured using a pendulum thrust balance. The source consists of permanent magnet (PM) arrays, a double turn rf loop antenna powered by a 13.56 MHz rf generator and a glass source tube. The PM arrays provide a magnetic nozzle near the open exit of the source and two configurations, which have maximum field strengths of about 100 and 270 G, are tested. A thrust of 15 mN, specific impulse of 2000 sec and a thrust efficiency of 8 percent are presently obtained for 2 kW of input power, 24 sccm flow rate of argon and the stronger magnetic field configuration.

  2. On the plasma flow inside magnetic tornadoes on the Sun

    NASA Astrophysics Data System (ADS)

    Wedemeyer, Sven; Steiner, Oskar

    2014-12-01

    High-resolution observations with the Swedish 1-m Solar Telescope (SST) and the Solar Dynamics Observatory (SDO) reveal rotating magnetic field structures that extend from the solar surface into the chromosphere and the corona. These so-called magnetic tornadoes are primarily detected as rings or spirals of rotating plasma in the Ca II 854.2 nm line core (also known as chromospheric swirls). Detailed numerical simulations show that the observed chromospheric plasma motion is caused by the rotation of magnetic field structures, which again are driven by photospheric vortex flows at their footpoints. Under the right conditions, two vortex flow systems are stacked on top of each other. We refer to the lower vortex, which extends from the low photosphere into the convection zone, as intergranular vortex flow (IVF). Once a magnetic field structure is co-located with an IVF, the rotation is mediated into the upper atmospheric layers and an atmospheric vortex flow (AVF, or magnetic tornado) is generated. In contrast to the recent work by Shelyag et al. (2013, ApJ, 776, L4), we demonstrate that particle trajectories in a simulated magnetic tornado indeed follow spirals and argue that the properties of the trajectories decisively depend on the location in the atmosphere and the strength of the magnetic field.

  3. Magnetic Field Measurement in Magnetized Laser Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, S.; Wallace, M. S.; Arias, A.; Morita, T.; Plechaty, C.; Huntington, C.; Martinez, D.; Ross, S. J.; Park, H.-S.; Presura, R.

    2013-10-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult when the field orientation is fluctuating in the plasma volume or when the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Based on an idea proposed by Tessarin et al. (2011), we implemented a solution to this problem to the field measurement in magnetized laser plasmas. High resolution spectra were obtained at the Nevada Terawatt Facility for plasmas created by 20 J, 400 fs Leopard laser pulses in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator. The components of the Al III 3s 2S1/2 - 3p 2P1 / 2 , 3 / 2 were recorded with space resolution along the direction normal to the target, which coincided with the magnetic field radius. In several shots, the spectra were time gated for 10 ns at different values of the magnetic field. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength can be measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  4. Interaction of a neutral cloud moving through a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.; Lu, G.

    1990-01-01

    Current collection by outgassing probes in motion relative to a magnetized plasma may be significantly affected by plasma processes that cause electron heating and cross field transport. Simulations of a neutral gas cloud moving across a static magnetic field are discussed. The authors treat a low-Beta plasma and use a 2-1/2 D electrostatic code linked with the authors' Plasma and Neutral Interaction Code (PANIC). This study emphasizes the understanding of the interface between the neutral gas cloud and the surrounding plasma where electrons are heated and can diffuse across field lines. When ionization or charge exchange collisions occur a sheath-like structure is formed at the surface of the neutral gas. In that region the crossfield component of the electric field causes the electron to E times B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating. The thermal electron current is significantly enhanced due to this heating.

  5. Negative specific heat of a magnetically self-confined plasma torus

    PubMed Central

    Kiessling, Michael K.-H.; Neukirch, Thomas

    2003-01-01

    It is shown that the thermodynamic maximum-entropy principle predicts negative specific heat for a stationary, magnetically self-confined current-carrying plasma torus. Implications for the magnetic self-confinement of fusion plasma are considered. PMID:12576553

  6. The Plasma Instrument for Magnetic Sounding (PIMS) for the Europa Mission

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; McNutt, R. L.; Kasper, J. C.; Case, A. W.; Rymer, A. M.; Stevens, M. L.; Jia, X.; Paty, C.; Khurana, K. K.; Kivelson, M. G.; Slavin, J. A.; Smith, H. T.; Korth, H.; Krupp, N.; Roussous, E.; Saur, J.

    2016-10-01

    We present the Plasma Instrument for Magnetic Sounding (PIMS) selected for the Europa Mission. We specifically address how PIMS plasma measurements will improve the accuracy of magnetic sounding of Europa's subsurface ocean.

  7. Experimental investigation in plasma relaxation by using a compact coaxial magnetized plasma gun in a background plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott

    2012-10-01

    A compact coaxial plasma gun is employed for experimental studies of plasma relaxation process being conducted in the HELCAT device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5 - 10kV. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities 1.2Cs and densities 10e20 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter lambda determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

  8. Spark plasma sintering of Mn-Al-C hard magnets.

    PubMed

    Pasko, A; LoBue, M; Fazakas, E; Varga, L K; Mazaleyrat, F

    2014-02-12

    Structural and magnetic characterization of isotropic Mn-Al-C bulk samples obtained by spark plasma sintering (SPS) is reported. This technique, to the best of our knowledge, has not been used for preparation of Mn-Al-based permanent magnets previously. Transformation from the parent -phase to the ferromagnetic τ-phase occurred on heating in the process of sintering. The phase constitution of the melt-spun precursors and consolidated samples was determined by x-ray diffraction. Magnetic hysteresis loops were recorded using a vibrating sample magnetometer. The compositional dependence of the coercivity, magnetization and density of the sintered materials is analysed. To combine good magnetic properties with proper densification, further optimization of the production parameters is necessary.

  9. Permanent magnet electron cyclotron resonance plasma source with remote window

    SciTech Connect

    Berry, L.A.; Gorbatkin, S.M. )

    1995-03-01

    An electron cyclotron resonance (ECR) plasma has been used in conjunction with a solid metal sputter target for Cu deposition over 200 mm diameters. The goal is to develop a deposition system and process suitable for filling submicron, high-aspect ratio ULSI features. The system uses a permanent magnet for creation of the magnetic field necessary for ECR, and is significantly more compact than systems equipped with electromagnets. A custom launcher design allows remote microwave injection with the microwave entrance window shielded from the copper flux. When microwaves are introduced at an angle with respect to the plasma, high electron densities can be produced with a plasma frequency significantly greater than the electron cyclotron frequency. Copper deposition rates of 1000 A/min have been achieved.

  10. Magnetically Controlled Optical Plasma Waveguide for Electron Acceleration

    SciTech Connect

    Pollock, B. B.; Davis, P.; Divol, L.; Glenzer, S. H.; Palastro, J. P.; Price, D.; Froula, D. H.; Tynan, G. R.

    2009-01-22

    In order to produce multi-Gev electrons from Laser Wakefield Accelerators, we present a technique to guide high power laser beams through underdense plasma. Experimental results from the Jupiter Laser Facility at the Lawrence Livermore National Laboratory that show density channels with minimum plasma densities below 5x10{sup 17} cm{sup -3} are presented. These results are obtained using an external magnetic field (<5 T) to limit the radial heat flux from a pre-forming laser beam. The resulting increased plasma pressure gradient produces a parabolic density gradient which is tunable by changing the external magnetic field strength. These results are compared with 1-D hydrodynamic simulations, while quasi-static kinetic simulations show that for these channel conditions 90% of the energy in a 150 TW short pulse beam is guided over 5 cm and predict electron energy gains of 3 GeV.

  11. Enhanced magnetic ionization in hydrogen reflex discharge plasma source

    SciTech Connect

    Toader, E.I.; Covlea, V.N.

    2005-03-01

    The effect of enhanced magnetic ionization on the external and internal parameters of a high-density, low pressure reflex plasma source operating in hydrogen is studied. The Langmuir probe method and Druyvesteyn procedure coupled with suitable software are used to measure the internal parameters. The bulk plasma region is free of an electric field and presents a high degree of uniformity. The electron energy distribution function is bi-Maxwellian with a dip/shoulder structure around 5.5 eV, independent of external parameters and radial position. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the electron density n{sub e} is as high as 10{sup 18} m{sup -3}, and the electron temperature T{sub e} is as low as a few tens of an electron volt, for dissipated energy of tens of Watts. The bulk plasma density scales with the dissipated power.

  12. Analysis of Electron Trajectories in Magnetized High Power Plasmas

    NASA Astrophysics Data System (ADS)

    Krueger, Dennis; Gallian, Sara; Trieschmann, Jan; Brinkmann, Ralf Peter

    2015-09-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is an important example of magnetized technological plasmas. With HiPIMS the focus lies on the generation of a high density plasma with a remarkably high degree of ionization. It can be used for the deposition of thin films with superior density and quality. Theoretical approaches to the regime of magnetized low temperature plasmas encounter some fundamental difficulties, for example concerning the details of the magnetic field configuration, the strongly varying degree of magnetization, and the frequent wall interactions. A kinetic single particle model is used for the investigations. Single electron trajectories are analyzed with the widely used Boris algorithm within the magnetized zone above the target (racetrack). We further examine a configuration where symmetry breaking occurs due to a potential bump, which is rotating azimuthally around the racetrack (spoke). Observing the effects of this structure on the single electron motion may allow us to obtain further insight into this phenomenon. This work is supported by the German Research Foundation in the frame of the Collaborative Research Centre TRR 87.

  13. Spectroscopic Measurements of Collision-less Coupling Between Explosive Debris Plasmas and Ambient, Magnetized Background Plasmas

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Schaeffer, Derek; Everson, Erik; Vincena, Stephen; van Compernolle, Bart; Constantin, Carmen; Clark, Eric; Niemann, Christoph

    2013-10-01

    Emission spectroscopy is currently being utilized in order to assess collision-less momentum and energy coupling between explosive debris plasmas and ambient, magnetized background plasmas of astrophysical relevance. In recent campaigns on the Large Plasma Device (LAPD) (nelec =1012 -1013 cm-3, Telec ~ 5 eV, B0 = 200 - 400 G) utilizing the new Raptor laser facility (1053 nm, 100 J per pulse, 25 ns FWHM), laser-ablated carbon debris plasmas were generated within ambient, magnetized helium background plasmas and prominent spectral lines of carbon and helium ions were studied in high spectral (0 . 01 nm) and temporal (50 ns) resolution. Time-resolved velocity components extracted from Doppler shift measurements of the C+4 227 . 1 nm spectral line along two perpendicular axes reveal significant deceleration as the ions stream and gyrate within the helium background plasma, indicating collision-less momentum coupling. The He+1 320 . 3 nm and 468 . 6 nm spectral lines of the helium background plasma are observed to broaden and intensify in response to the carbon debris plasma, indicative of strong electric fields (Stark broadening) and energetic electrons. The experimental results are compared to 2D hybrid code simulations.

  14. Lectin-Magnetic Beads for Plasma Membrane Isolation.

    PubMed

    Lee, Yu-Chen; Liu, Hsuan-Chen; Chuang, Carol; Lin, Sue-Hwa

    2015-07-01

    Plasma membrane proteins mainly function to transmit external signals into the cell. Many plasma membrane receptor tyrosine kinases (e.g., HER2 and EGFR) are known to mediate oncogenic progression, making them prime targets for cancer therapy. Recently, it has become important to identify plasma membrane proteins that are differentially expressed in normal versus cancer cells, in drug-sensitive versus drug-resistant cells, or among tumor cells that metastasize to different organ sites because these differentially expressed membrane proteins may lead to the identification of therapeutic targets or diagnostic markers. In addition, there is an increased interest in identifying cell-surface proteins that could serve as markers for stem cells, progenitor cells, or cells of different lineages. Traditionally, membrane isolation requires multiple centrifugation steps to isolate different organelles based on their density. With the advent of affinity matrix technology, it is possible to separate organelles based on their molecular differences. A defining characteristic of the plasma membrane is that plasma membrane proteins are more extensively glycosylated than are intracellular membrane proteins. As a result, affinity chromatography employing lectin, a carbohydrate-binding protein, is commonly used to isolate plasma membrane proteins. We have extended this concept for plasma membrane isolation by using concanavalin A (ConA), a lectin with mannose specificity. Here we describe a protocol that uses immobilized ConA bound to magnetic beads to isolate plasma membranes from homogenized cell lysates. The captured plasma membrane proteins are then solubilized from the ConA-magnetic beads by detergents in the presence of a competing sugar, methyl α-mannopyranoside.

  15. Multipole moments of bumpy black holes

    SciTech Connect

    Vigeland, Sarah J.

    2010-11-15

    General relativity predicts the existence of black holes, compact objects whose spacetimes depend only on their mass, spin, and charge in vacuum (the 'no-hair' theorem). As various observations probe deeper into the strong fields of black hole candidates, it is becoming possible to test this prediction. Previous work suggested that such tests can be performed by measuring whether the multipolar structure of black hole candidates has the form that general relativity demands, and introduced a family of 'bumpy black hole' spacetimes to be used for making these measurements. These spacetimes have generalized multipoles, where the deviation from the Kerr metric depends on the spacetime's 'bumpiness'. In this paper, we show how to compute the Geroch-Hansen moments of a bumpy black hole, demonstrating that there is a clean mapping between the deviations used in the bumpy black hole formalism and the Geroch-Hansen moments. We also extend our previous results to define bumpy black holes whose current moments, analogous to magnetic moments of electrodynamics, deviate from the canonical Kerr value.

  16. Study on spatial distribution of plasma parameters in a magnetized inductively coupled plasma

    SciTech Connect

    Cheong, Hee-Woon; Lee, Woohyun; Kim, Ji-Won; Whang, Ki-Woong; Kim, Hyuk; Park, Wanjae

    2015-07-15

    Spatial distributions of various plasma parameters such as plasma density, electron temperature, and radical density in an inductively coupled plasma (ICP) and a magnetized inductively coupled plasma (M-ICP) were investigated and compared. Electron temperature in between the rf window and the substrate holder of M-ICP was higher than that of ICP, whereas the one just above the substrate holder of M-ICP was similar to that of ICP when a weak (<8 G) magnetic field was employed. As a result, radical densities in M-ICP were higher than those in ICP and the etch rate of oxide in M-ICP was faster than that in ICP without severe electron charging in 90 nm high aspect ratio contact hole etch.

  17. Plasma Equilibrium in a Magnetic Field with Stochastic Regions

    SciTech Connect

    J.A. Krommes and Allan H. Reiman

    2009-04-23

    The nature of plasma equilibrium in a magnetic field with stochastic regions is examined. It is shown that the magnetic differential equation that determines the equilibrium Pfirsch-Schluter currents can be cast in a form similar to various nonlinear equations for a turbulent plasma, allowing application of the mathematical methods of statistical turbulence theory. An analytically tractable model, previously studied in the context of resonance-broadening theory, is applied with particular attention paid to the periodicity constraints required in toroidal configurations. It is shown that even a very weak radial diffusion of the magnetic field lines can have a significant effect on the equilibrium in the neighborhood of the rational surfaces, strongly modifying the near-resonant Pfirsch-Schluter currents. Implications for the numerical calculation of 3D equilibria are discussed

  18. Antiproton powered propulsion with magnetically confined plasma engines

    SciTech Connect

    Lapointe, M.R.

    1989-08-01

    Matter-antimatter annihilation releases more energy per unit mass than any other method of energy production, making it an attractive energy source for spacecraft propulsion. In the magnetically confined plasma engine, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas. The resulting charged annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. The calculated energy transfer efficiencies for a low number density (10(14)/cu cm) hydrogen propellant are insufficient to warrant operating the engine in this mode. Efficiencies are improved using moderate propellant number densities (10(16)/cu cm), but the energy transferred to the plasma in a realistic magnetic mirror system is generally limited to less than 2 percent of the initial proton-antiproton annihilation energy. The energy transfer efficiencies are highest for high number density (10(18)/cu cm) propellants, but plasma temperatures are reduced by excessive radiation losses. Low to moderate thrust over a wide range of specific impulse can be generated with moderate propellant number densities, while higher thrust but lower specific impulse may be generated using high propellant number densities. Significant mass will be required to shield the superconducting magnet coils from the high energy gamma radiation emitted by neutral pion decay. The mass of such a radiation shield may dominate the total engine mass, and could severely diminish the performance of antiproton powered engines which utilize magnetic confinement. The problem is compounded in the antiproton powered plasma engine, where lower energy plasma bremsstrahlung radiation may cause shield surface ablation and degradation.

  19. Antiproton powered propulsion with magnetically confined plasma engines

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1989-01-01

    Matter-antimatter annihilation releases more energy per unit mass than any other method of energy production, making it an attractive energy source for spacecraft propulsion. In the magnetically confined plasma engine, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas. The resulting charged annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. The calculated energy transfer efficiencies for a low number density (10(14)/cu cm) hydrogen propellant are insufficient to warrant operating the engine in this mode. Efficiencies are improved using moderate propellant number densities (10(16)/cu cm), but the energy transferred to the plasma in a realistic magnetic mirror system is generally limited to less than 2 percent of the initial proton-antiproton annihilation energy. The energy transfer efficiencies are highest for high number density (10(18)/cu cm) propellants, but plasma temperatures are reduced by excessive radiation losses. Low to moderate thrust over a wide range of specific impulse can be generated with moderate propellant number densities, while higher thrust but lower specific impulse may be generated using high propellant number densities. Significant mass will be required to shield the superconducting magnet coils from the high energy gamma radiation emitted by neutral pion decay. The mass of such a radiation shield may dominate the total engine mass, and could severely diminish the performance of antiproton powered engines which utilize magnetic confinement. The problem is compounded in the antiproton powered plasma engine, where lower energy plasma bremsstrahlung radiation may cause shield surface ablation and degradation.

  20. Magnetically controlled deposition of metals using gas plasma. Final report

    SciTech Connect

    1998-04-02

    This is the first phase of a project that has the objective to develop a method of spraying materials on a substrate in a controlled manner to eliminate the waste and hazardous material generation inherent in present plating processes. The project is considering plasma spraying of metal on a substrate using magneto-hydrodynamics to control the plasma/metal stream. The process being developed is considering the use of commercially available plasma torches to generate the plasma/metal stream. The plasma stream is collimated, and directed using magnetic forces to the extent required for precise control of the deposition material. The project will be completed in phases. Phase one of the project, the subject of this grant, is the development of an analytical model that can be used to determine the feasibility of the process and to design a laboratory scale demonstration unit. The contracted time is complete, and the research is still continuing. This report provides the results obtained to date. As the model and calculations are completed those results will also be provided. This report contains the results of the computer code that have been completed to date. Results from a ASMEE Benchmark problem, flow over a backward step with heat transfer, Couette flow with magnetic forces, free jet flow are presented along with several other check calculations that are representative of the cases that were calculated in the course of the development process. The final cases that define a velocity field in the exit of a plasma spray torch with and without a magnetic field are in process. A separate program (SPRAY) has been developed that can track the plating material to the substrate and describe the distribution of the material on the substrate. When the jet calculations are complete SPRAY will be used to compare the distribution of material on the substrate with and without the effect of the magnetic focus.

  1. Cluster multipole theory for anomalous Hall effect in antiferromagnets

    NASA Astrophysics Data System (ADS)

    Suzuki, M.-T.; Koretsune, T.; Ochi, M.; Arita, R.

    2017-03-01

    We introduce a cluster extension of multipole moments to discuss the anomalous Hall effect (AHE) in both ferromagnetic (FM) and antiferromagnetic (AFM) states in a unified framework. We first derive general symmetry requirements for the AHE in the presence or absence of the spin-orbit coupling by considering the symmetry of the Berry curvature in k space. The cluster multipole (CMP) moments are then defined to quantify the macroscopic magnetization in noncollinear AFM states as a natural generalization of the magnetization in FM states. We identify the macroscopic CMP order which induces the AHE. The theoretical framework is applied to the noncollinear AFM states of Mn3Ir , for which an AHE was predicted in a first-principles calculation, and Mn3Z (Z =Sn ,Ge ), for which a large AHE was recently discovered experimentally. We further compare the AHE in Mn3Z and bcc Fe in terms of the CMP. We show that the AHE in Mn3Z is characterized by the magnetization of a cluster octupole moment in the same manner as that in bcc Fe characterized by the magnetization of the dipole moment.

  2. Resonant enhancement for amplitude-modulated laser filament induced magnetic field in an inhomogeneous plasma

    NASA Astrophysics Data System (ADS)

    Annou, R.; Tripathi, V. K.; Srivastava, M. P.

    1996-09-01

    The Tripathi-Liu [Phys. Plasmas 1, 990 (1994)] model of magnetic-field generation due to an amplitude-modulated laser in a plasma is revisited. At plasma resonance, where modulation frequency equals the plasma frequency, significant enhancement in the magnetic field is seen. The magnetic field is found to scale directly with laser intensity and plasma frequency, while scaling inversely with laser spot size.

  3. Inverse mirror plasma experimental device (IMPED) - a magnetized linear plasma device for wave studies

    NASA Astrophysics Data System (ADS)

    Bose, Sayak; Chattopadhyay, P. K.; Ghosh, J.; Sengupta, S.; Saxena, Y. C.; Pal, R.

    2015-04-01

    In a quasineutral plasma, electrons undergo collective oscillations, known as plasma oscillations, when perturbed locally. The oscillations propagate due to finite temperature effects. However, the wave can lose the phase coherence between constituting oscillators in an inhomogeneous plasma (phase mixing) because of the dependence of plasma oscillation frequency on plasma density. The longitudinal electric field associated with the wave may be used to accelerate electrons to high energies by exciting large amplitude wave. However when the maximum amplitude of the wave is reached that plasma can sustain, the wave breaks. The phenomena of wave breaking and phase mixing have applications in plasma heating and particle acceleration. For detailed experimental investigation of these phenomena a new device, inverse mirror plasma experimental device (IMPED), has been designed and fabricated. The detailed considerations taken before designing the device, so that different aspects of these phenomena can be studied in a controlled manner, are described. Specifications of different components of the IMPED machine and their flexibility aspects in upgrading, if necessary, are discussed. Initial results meeting the prerequisite condition of the plasma for such study, such as a quiescent, collisionless and uniform plasma, are presented. The machine produces δnnoise/n <= 1%, Luniform ~ 120 cm at argon filling pressure of ~10-4 mbar and axial magnetic field of B = 1090 G.

  4. Corrosion behavior of magnetic ferrite coating prepared by plasma spraying

    SciTech Connect

    Liu, Yi; Wei, Shicheng Tong, Hui; Tian, Haoliang; Liu, Ming; Xu, Binshi

    2014-12-15

    Graphical abstract: The saturation magnetization (M{sub s}) of the ferrite coating is 34.417 emu/g while the M{sub s} value of the ferrite powder is 71.916 emu/g. It can be seen that plasma spray process causes deterioration of the room temperature soft magnetic properties. - Highlights: • Spinel ferrite coatings have been prepared by plasma spraying. • The coating consists of nanocrystalline grains. • The saturation magnetization of the ferrite coating is 34.417 emu/g. • Corrosion behavior of the ferrite coating was examined in NaCl solution. - Abstract: In this study, spray dried spinel ferrite powders were deposited on the surface of mild steel substrate through plasma spraying. The structure and morphological studies on the ferrite coatings were carried out using X-ray diffraction, scanning electron microscope and Raman spectroscopy. It was showed that spray dried process was an effective method to prepare thermal spraying powders. The coating showed spinel structure with a second phase of LaFeO{sub 3}. The magnetic property of the ferrite samples were measured by vibrating sample magnetometer. The saturation magnetization (M{sub s}) of the ferrite coating was 34.417 emu/g. The corrosion behavior of coating samples was examined by electrochemical impedance spectroscopy. EIS diagrams showed three corrosion processes as the coating immersed in 3.5 wt.% NaCl solution. The results suggested that plasma spraying was a promising technology for the production of magnetic ferrite coatings.

  5. Exponential frequency spectrum and Lorentzian pulses in magnetized plasmas

    SciTech Connect

    Pace, D. C.; Shi, M.; Maggs, J. E.; Morales, G. J.; Carter, T. A.

    2008-12-15

    Two different experiments involving pressure gradients across the confinement magnetic field in a large plasma column are found to exhibit a broadband turbulence that displays an exponential frequency spectrum for frequencies below the ion cyclotron frequency. The exponential feature has been traced to the presence of solitary pulses having a Lorentzian temporal signature. These pulses arise from nonlinear interactions of drift-Alfven waves driven by the pressure gradients. In both experiments the width of the pulses is narrowly distributed resulting in exponential spectra with a single characteristic time scale. The temporal width of the pulses is measured to be a fraction of a period of the drift-Alfven waves. The experiments are performed in the Large Plasma Device (LAPD-U) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] operated by the Basic Plasma Science Facility at the University of California, Los Angeles. One experiment involves a controlled, pure electron temperature gradient associated with a microscopic (6 mm gradient length) hot electron temperature filament created by the injection a small electron beam embedded in the center of a large, cold magnetized plasma. The other experiment is a macroscopic (3.5 cm gradient length) limiter-edge experiment in which a density gradient is established by inserting a metallic plate at the edge of the nominal plasma column of the LAPD-U. The temperature filament experiment permits a detailed study of the transition from coherent to turbulent behavior and the concomitant change from classical to anomalous transport. In the limiter experiment the turbulence sampled is always fully developed. The similarity of the results in the two experiments strongly suggests a universal feature of pressure-gradient driven turbulence in magnetized plasmas that results in nondiffusive cross-field transport. This may explain previous observations in helical confinement devices, research tokamaks, and arc plasmas.

  6. A linear radio frequency plasma reactor for potential and current mapping in a magnetized plasma

    SciTech Connect

    Faudot, E.; Devaux, S.; Moritz, J.; Heuraux, S.; Molina Cabrera, P.; Brochard, F.

    2015-06-15

    Langmuir probe measurements in front of high power ion cyclotron resonant frequency antennas are not possible or simply too noisy to be analyzed properly. A linear experiment is a radio frequency (RF) magnetized plasma discharge reactor designed to probe the rectified potential in front of such antennas but at low power level (1 kW) to next improve antenna design and mitigate sheath effects. The maximum magnetic field is 0.1 T, and the RF amplifier can work between 10 kHz and 250 MHz allowing ion cyclotron resonances for argon or helium. The first measurements with no magnetic field are presented here, especially 2D potential maps extracted from the RF compensated probe measurements yield ni ≈ 10{sup 15} m{sup −3} and Te ≈ 2 eV for RF power lower than 100 W. Series resonances in the chamber are highlighted and allow to deduce the plasma parameters from a simple equivalent impedance model of the plasma in helium gas. Next studies will be focused on magnetized plasmas and especially magnetized RF sheaths.

  7. A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

    NASA Astrophysics Data System (ADS)

    Hu, Guangyue; Liang, Yihan; Song, Falun; Yuan, Peng; Wang, Yulin; Zhao, Bin; Zheng, Jian

    2015-02-01

    A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast (~230 ns), 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device (ICCD) detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.

  8. Magnetized Fast ignition (MFI) and Laser Plasma Interactions in Strong Magnetic Field

    NASA Astrophysics Data System (ADS)

    Mima, Kunioki; Johzaki, T.; Honrubia, J.; Nagatomo, H.; Taguchi, T.; Sunahara, A.; Sakagami, H.; Fujioka, S.; Logan, G.

    2016-03-01

    In this paper, magnetized fast ignition (MFI) is proposed for improving the coupling efficiency of a heating laser to a core plasma. In the MFI, the external magnetic field is applied to reduce the hot electron energy and focus the dense hot electron flux to the core. The external magnetic field higher than 100T is generated by the laser driven coil and it is amplified by the implosion. The magnetic field at the tip of the cone is expected to reach higher than 10kT and the laser plasma interaction and the hot electron transport are modified. As the results of applying the external magnetic field, hot electron energy is reduced to less than 5MeV for the laser intensity of 1020W/ cm2 and the Weibel instability is suppressed to collimate the hot electron beam to the core.

  9. Model of magnetic reconnection in space and astrophysical plasmas

    SciTech Connect

    Boozer, Allen H.

    2013-03-15

    Maxwell's equations imply that exponentially smaller non-ideal effects than commonly assumed can give rapid magnetic reconnection in space and astrophysical plasmas. In an ideal evolution, magnetic field lines act as stretchable strings, which can become ever more entangled but cannot be cut. High entanglement makes the lines exponentially sensitive to small non-ideal changes in the magnetic field. The cause is well known in popular culture as the butterfly effect and in the theory of deterministic dynamical systems as a sensitive dependence on initial conditions, but the importance to magnetic reconnection is not generally recognized. Two-coordinate models are too constrained geometrically for the required entanglement, but otherwise the effect is general and can be studied in simple models. A simple model is introduced, which is periodic in the x and y Cartesian coordinates and bounded by perfectly conducting planes in z. Starting from a constant magnetic field in the z direction, reconnection is driven by a spatially smooth, bounded force. The model is complete and could be used to study the impulsive transfer of energy between the magnetic field and the ions and electrons using a kinetic plasma model.

  10. Ultra-High Intensity Magnetic Field Generation in Dense Plasma

    SciTech Connect

    Fisch, Nathaniel J

    2014-01-08

    I. Grant Objective The main objective of this grant proposal was to explore the efficient generation of intense currents. Whereasthefficient generation of electric current in low-­energy-­density plasma has occupied the attention of the magnetic fusion community for several decades, scant attention has been paid to carrying over to high-­energy-­density plasma the ideas for steady-­state current drive developed for low-­energy-­density plasma, or, for that matter, to inventing new methodologies for generating electric current in high-­energy-­density plasma. What we proposed to do was to identify new mechanisms to accomplish current generation, and to assess the operation, physics, and engineering basis of new forms of current drive in regimes appropriate for new fusion concepts.

  11. MAGNETIC NULL POINTS IN KINETIC SIMULATIONS OF SPACE PLASMAS

    SciTech Connect

    Olshevsky, Vyacheslav; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni; Deca, Jan; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano

    2016-03-01

    We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind, and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3–9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their cross sections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

  12. Effective magnetization of the dust particles in a complex plasma

    NASA Astrophysics Data System (ADS)

    Kählert, Hanno

    2012-10-01

    The large mass and size of the dust particles in a complex plasma has several advantages, including low characteristic frequencies on the order of a few Hz and the ability to record their motion with video cameras. However, these properties pose major difficulties for achieving strong magnetization. While the light electrons and ions can be magnetized by (superconducting) magnets, magnetizing the heavy dust component is extremely challenging. Instead of further increasing the magnetic field strengths or decreasing the particle size, we use the analogy between the Lorentz force and the Coriolis force experienced by particles in a rotating reference frame to create ``effective magnetic fields'' which is a well-established technique in the field of trapped quantum gases [1]. To induce rotation in a complex plasma, we take advantage of the neutral drag force, which allows to transmit the motion of a rotating neutral gas to the dust particles [2]. The equations of motion in the rotating frame agree with those in a stationary gas except for the additional centrifugal and Coriolis forces [3]. Due to the slow rotation frequencies (˜ Hz) and contrary to the situation in a strong magnetic field, only the properties of the heavy dust particles are notably affected. Experiments with a rotating electrode realize the desired velocity profile for the neutral gas and allow us to verify the efficiency of the concept [3].[4pt] This work was performed in collaboration with J. Carstensen, M. Bonitz, H. L"owen, F. Greiner, and A. Piel.[4pt] [1] A. L. Fetter, Rev. Mod. Phys. 81, 647 (2009)[0pt] [2] J. Carstensen, F. Greiner, L.-J. Hou, H. Maurer, and A. Piel, Phys. Plasmas 16, 013702 (2009)[0pt] [3] H. K"ahlert, J. Carstensen, M. Bonitz, H. L"owen, F. Greiner, and A. Piel, submitted for publication, arXiv:1206.5073

  13. Matched dipole probe for precise electron density measurements in magnetized and non-magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Rafalskyi, Dmytro; Aanesland, Ane

    2015-09-01

    We present a plasma diagnostics method based on impedance measurements of a short matched dipole placed in the plasma. This allows measuring the local electron density in the range from 1012-1015 m-3 with a magnetic field of at least 0-50 mT. The magnetic field strength is not directly influencing the data analysis and requires only that the dipole probe is oriented perpendicularly to the magnetic field. As a result, the magnetic field can be non-homogeneous or even non-defined within the probe length without any effect on the final tolerance of the measurements. The method can be applied to plasmas of relatively small dimensions (< 10 cm) and doesn't require any special boundary conditions. The high sensitivity of the impedance measurements is achieved by using a miniature matching system installed close to the probe tip, which also allows to suppress sheath resonance effects. We experimentally show here that the tolerance of the electron density measurements reaches values lower than 1%, both with and without the magnetic field. The method is successfully validated by both analytical modeling and experimental comparison with Langmuir probes. The validation experiments are conducted in a low pressure (1 mTorr) Ar discharge sustained in a 10 cm size plasma chamber with and without a transversal magnetic field of about 20 mT. This work was supported by a Marie Curie International Incoming Fellowships within FP7 (NEPTUNE PIIF-GA-2012-326054).

  14. A gyrokinetic collision operator for magnetized Lorentz plasmas

    SciTech Connect

    Liu Chang; Ma Chenhao; Yu Xiongjie; Qin, Hong

    2011-03-15

    A gyrocenter collision operator for magnetized Lorentz plasmas is derived using the Fokker-Plank method. The gyrocenter collision operator consists of drift and diffusion terms in the gyrocenter coordinates, including the diffusion of the gyrocenter, which does not exist for the collision operator in the particle phase space coordinates. The gyrocenter collision operator also depends on the transverse electric field explicitly, which is crucial for the correct treatment of collisional effects and transport in the gyrocenter coordinates. The gyrocenter collision operator derived is applied to calculate the particle and heat transport fluxes in a magnetized Lorentz plasma with an electric field. The particle and heat transport fluxes calculated from our gyrocenter collision operator agree exactly with the classical Braginskii's result [S. I. Braginskii, Reviews of Plasma Physics (Consultants Bureau, New York, 1965), Vol. 1, p. 205: P. Helander and D. J. Sigmar, Collisional Transport in Magnetized Plasmas (Cambridge University, Cambridge, 2002), p. 65], which validates the correctness of our collision operator. To calculate the transport fluxes correctly, it is necessary to apply the pullback transformation associated with gyrocenter coordinate transformation in the presence of collisions, which also serves as a practical algorithm for evaluating collisional particle and heat transport fluxes in the gyrocenter coordinates.

  15. Nonlocal electron transport in magnetized plasmas with arbitrary atomic number

    SciTech Connect

    Bennaceur-Doumaz, D.; Bendib, A.

    2006-09-15

    The numerical solution of the steady-state electron Fokker-Planck equation perturbed with respect to a global equilibrium is presented in magnetized plasmas with arbitrary atomic number Z. The magnetic field is assumed to be constant and the electron-electron collisions are described by the Landau collision operator. The solution is derived in the Fourier space and in the framework of the diffusive approximation which captures the spatial nonlocal effects. The transport coefficients are deduced and used to close a complete set of nonlocal electron fluid equations. This work improves the results of A. Bendib et al. [Phys. Plasmas 9, 1555 (2002)] and of A. V. Brantov et al. [Phys. Plasmas 10, 4633 (2003)] restricted to the local and nonlocal high-Z plasma approximations, respectively. The influence of the magnetic field on the nonlocal effects is discussed. We propose also accurate numerical fits of the relevant transport coefficients with respect to the collisionality parameter {lambda}{sub ei}/L and the atomic number Z, where L is the typical scale length and {lambda}{sub ei} is the electron-ion mean-free-path.

  16. Magnetically Controlled Plasma Waveguide For Laser Wakefield Acceleration

    SciTech Connect

    Froula, D H; Divol, L; Davis, P; Palastro, J; Michel, P; Leurent, V; Glenzer, S H; Pollock, B; Tynan, G

    2008-05-14

    An external magnetic field applied to a laser plasma is shown produce a plasma channel at densities relevant to creating GeV monoenergetic electrons through laser wakefield acceleration. Furthermore, the magnetic field also provides a pressure to help shape the channel to match the guiding conditions of an incident laser beam. Measured density channels suitable for guiding relativistic short-pulse laser beams are presented with a minimum density of 5 x 10{sup 17} cm{sup -3} which corresponds to a linear dephasing length of several centimeters suitable for multi-GeV electron acceleration. The experimental setup at the Jupiter Laser Facility, Lawrence Livermore National Laboratory, where a 1-ns, 150 J 1054 nm laser will produce a magnetically controlled channel to guide a < 75 fs, 10 J short-pulse laser beam through 5-cm of 5 x 10{sup 17} cm{sup -3} plasma is presented. Calculations presented show that electrons can be accelerated to 3 GeV with this system. Three-dimensional resistive magneto-hydrodynamic simulations are used to design the laser and plasma parameters and quasi-static kinetic simulations indicate that the channel will guide a 200 TW laser beam over 5-cm.

  17. Magnetic island and plasma rotation under external resonant magnetic perturbation in the T-10 tokamak

    SciTech Connect

    Eliseev, L. G.; Ivanov, N. V. Kakurin, A. M.; Perfilov, S. V.; Melnikov, A. V.

    2015-05-15

    Experimental comparison of the m = 2, n = 1 mode and plasma rotation velocities at q = 2 magnetic surface in a wide range of the mode amplitudes is presented. Phase velocity of the mode rotation is measured with a set of poloidal magnetic field sensors located at the inner side of the vacuum vessel wall. Plasma rotation velocity at the q = 2 magnetic surface in the direction of the mode phase velocity is measured with the heavy ion beam probe diagnostics. In the presence of a static Resonant Magnetic Perturbation (RMP), the rotation is irregular that appears as cyclical variations of the mode and plasma instantaneous velocities. The period of these variations is equal to the period of the mode oscillations. In the case of high mode amplitude, the rotation irregularity of the mode is consistent with the rotation irregularity of the resonant plasma layer. On the contrary, the observed rise of the mode rotation irregularity in the case of low mode amplitude occurs without an increase of the rotation irregularity of the resonant plasma layer. The experimental results are simulated and analyzed with the TEAR code based on the two-fluid MHD approximation. Calculated irregularities of the mode and plasma rotation depend on the mode amplitude similar to the experimental data. For large islands, the rotation irregularity is attributed to oscillations of the electromagnetic torque applied to the resonant plasma layer. For small islands, the deviation of the mode rotation velocity from the plasma velocity occurs due to the effect of finite plasma resistivity.

  18. MHD Simulation of Plasma Flow through the VASIMR Magnetic Nozzle

    NASA Astrophysics Data System (ADS)

    Tarditi, A. G.; Shebalin, J. V.

    2003-10-01

    The VASIMR (Variable Specific Impulse Magnetoplasma Rocket, [1]) concept is currently in the experimental development phase at the Advanced Space Propulsion Laboratory, NASA Johnson Space Center. The current experimental effort is mainly focused on the demonstration of the efficient plasma production (light ion helicon source, [2]) and energy boosting (ion cyclotron resonance heating section). Two other critical issues, the plasma detachment process and the collimation of the plasma plume in the magnetic nozzle, are essential for the near term experimental development and are being addressed through an MHD simulation modeling effort with the NIMROD code [3,4]. The model follows the plasma flow up to few meters from the nozzle throat: at that distance the plasma exhaust parameters reach values comparable with the ionospheric plasma background [5]. Results from two-dimensional simulation runs (cylindrical geometry, assuming azimuthal symmetry) aimed in particular at testing the effectiveness of different open-end boundary condition schemes are presented. [1] F. R. Chang-Diaz, Scientific American, p. 90, Nov. 2000 [2] M. D. Carter, et al., Phys. Plasmas 9, 5097-5110, 2002 [3] http://www.nimrodteam.org [4] A. Tarditi et al., 28th Int. Electric Propulsion Conf., IEPC 2003, Toulouse, France, March 2003 [5] A. V. Ilin et al., Proc. 40th AIAA Aerospace Sciences Meeting, Reno, NV, Jan. 2002

  19. Large-Area Permanent-Magnet ECR Plasma Source

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2007-01-01

    A 40-cm-diameter plasma device has been developed as a source of ions for material-processing and ion-thruster applications. Like the device described in the immediately preceding article, this device utilizes electron cyclotron resonance (ECR) excited by microwave power in a magnetic field to generate a plasma in an electrodeless (noncontact) manner and without need for an electrically insulating, microwave-transmissive window at the source. Hence, this device offers the same advantages of electrodeless, windowless design - low contamination and long operational life. The device generates a uniform, high-density plasma capable of sustaining uniform ion-current densities at its exit plane while operating at low pressure [<10(exp -4) torr (less than about 1.3 10(exp -2) Pa)] and input power <200 W at a frequency of 2.45 GHz. Though the prototype model operates at 2.45 GHz, operation at higher frequencies can be achieved by straightforward modification to the input microwave waveguide. Higher frequency operation may be desirable in those applications that require even higher background plasma densities. In the design of this ECR plasma source, there are no cumbersome, power-hungry electromagnets. The magnetic field in this device is generated by a permanent-magnet circuit that is optimized to generate resonance surfaces. The microwave power is injected on the centerline of the device. The resulting discharge plasma jumps into a "high mode" when the input power rises above 150 W. This mode is associated with elevated plasma density and high uniformity. The large area and uniformity of the plasma and the low operating pressure are well suited for such material-processing applications as etching and deposition on large silicon wafers. The high exit-plane ion-current density makes it possible to attain a high rate of etching or deposition. The plasma potential is <3 V low enough that there is little likelihood of sputtering, which, in plasma processing, is undesired

  20. Analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma

    SciTech Connect

    Shukla, Arun; Jat, K. L.

    2015-07-31

    An analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma has been reported. In the present analytical investigation, the lattice displacement, acousto-optical polarization, susceptibility, acousto-optical gain constant arising due to the induced nonlinear current density and acousto-optical process are deduced in an acoustically perturbed Brillouin active magnetized semiconductor plasma using the hydrodynamical model of plasma and coupled mode scheme. The influence of wave number and magnetic field has been explored. The analysis has been applied to centrosymmetric crystal. Numerical estimates are made for n-type InSb crystal duly irradiated by a frequency doubled 10.6 µm CO{sub 2} laser. It is found that lattice displacement, susceptibility and acousto-optical gain increase linearly with incident wave number and applied dc magnetic field, while decrease with scattering angle. The gain also increases with electric amplitude of incident laser beam. Results are found to be well in agreement with available literature.

  1. Study of the performance of antennas in magnetized plasmas

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1975-01-01

    The antenna studies were performed in a large magnetized plasma source, a schematic drawing of which is shown. The plasma diagnostics consist of a 70 GHz (4 mm) microwave interferometer for density measurements and of various Langmuir probes for spatially resolved measurements of t sub e, n sub e and the shape of the electron distribution function. All diagnostic data are time-resolved by sample-and-hold techniques so as to yield information about the plasma build-up, the steady-state discharge, and the plasma decay in the afterglow. Whistler waves are excited and detected with various antennas which are inserted into the center of the plasma column through one axial and two orthogonal radial ports. The antennas were tested for their proper dipole response and then calibrated in a known field geometry in air. For the electric dipole, a parallel plate capacitor field was used; the magnetic loop is calibrated in the near-zone field of a long linear conductor of known radio frequency current distribution. Results are presented and discussed.

  2. Magnetic Field Measurements in Plasmas: Beyond the Traditional Zeeman Spectroscopy

    SciTech Connect

    Doron, R.; Stambulchik, E.; Tessarin, S.; Kroupp, E.; Citrin, J.; Maron, Y.; Tsigutkin, K.

    2009-09-10

    We discuss a new approach to measure magnetic fields in situations where the magnetic-field properties and/or the plasma regime make the traditional Zeeman spectroscopy inapplicable. The approach is particularly useful when the field direction and/or magnitude vary significantly in the region viewed or during the diagnostic system's integration time, and hence no Zeeman splitting can be observed. Similar difficulty may also occur for high-energy-density conditions, where the Zeeman pattern is often completely smeared, regardless of the field distribution, due to the dominant contributions of the Stark and Doppler broadenings to the spectral-line shapes. In the new approach, the magnetic field is inferred from the comparison of the line-shapes of different fine-structure components of the same multiplet, which practically have the same Stark and Doppler broadenings, but different magnetic-field-induced contributions. Limitations of the new method are discussed.

  3. Studying astrophysical particle acceleration mechanisms with colliding magnetized laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fox, W.; Deng, W.; Bhattacharjee, A.; Fiksel, G.; Nilson, P.; Haberberger, D.; Chang, P.-Y.; Barnak, D.

    2015-11-01

    Significant particle energization is observed to occur in many astrophysical environments, and in the standard models this acceleration occurs as a part of the energy conversion processes associated with collisionless shocks or magnetic reconnection. A recent generation of laboratory experiments conducted using magnetized laser-produced plasmas has opened opportunities to study these particle acceleration processes in the laboratory. Ablated plasma plumes are externally magnetized using an externally-applied magnetic field in combination with a low-density background plasma. Colliding unmagnetized plasmas demonstrated ion-driven Weibel instability while colliding magnetized plasmas drive magnetic reconnection. Both magnetized and unmagnetized colliding plasma are modeled with electromagnetic particle-in-cell simulations which provide an end-to-end model of the experiments. Using particle-in-cell simulations, we provide predictions of particle acceleration driven by reconnection, resulting from both direct x-line acceleration and Fermi-like acceleration at contracting magnetic fields lines near magnetic islands.

  4. Magnetic monopole plasma oscillations and the survival of Galactic magnetic fields

    SciTech Connect

    Parker, E.N.

    1987-10-01

    This paper explores the general nature of magnetic-monopole plasma oscillations as a theoretical possibility for the observed Galactic magnetic field in the presence of a high abundance of magnetic monopoles. The modification of the hydromagnetic induction equation by the monopole oscillations produces the half-velocity effect, in which the magnetic field is transported bodily with a velocity midway between the motion of the conducting fluid and the monopole plasma. Observational studies of the magnetic field in the Galaxy, and in other galaxies, exclude the half-velocity effect, indicating that the magnetic fields is not associated with monopole oscillations. In any case the phase mixing would destroy the oscillations in less than 100 Myr. The conclusion is that magnetic monopole oscillations do not play a significant role in the galactic magnetic fields. Hence the existence of galactic magnetic fields places a low limit on the monopole flux, so that their detection - if they exist at all - requires a collecting area at least as large as a football field. 47 references.

  5. Scaling of the beam plasma discharge for low magnetic fields

    NASA Technical Reports Server (NTRS)

    Papadopoulos, K.

    1986-01-01

    A theoretical analysis of the scaling law and the value of the threshold current for beam plasma discharge (BPD) is presented, based on the requirement for an absolute instability near the plasma frequency. It is shown that both the scaling law as well as the numerical values of Ic are consistent with the experimental data, in the low pressure regimes and for weak magnetic field experiments if the dominant particle loss mechanism is due to Bohm diffusion. The implications of the findings to electron injection in space are discussed.

  6. Coupled Dust-Lattice Modes in Magnetized Complex Plasmas

    SciTech Connect

    Farokhi, B.; Shahmansouri, M.

    2008-09-07

    Dust lattice wave modes in a one dimensional plasma crystal (formed by paramagnetic dust particles) suspended in the plasma sheath are studied. The ion flow in the sheath introduces 'ion wakes' below the crystal particles. The wave dispersion relations are found under the influence of inhomogeneous magnetic field, wake charge effect and equilibrium charge gradient. The expression for the wave dispersion relations clearly show that three branches exist as a result of the coupling of longitudinal and transverse modes due to the Lorenz forces, charge gradient and wake charge effect. We observe a new coupling between the dust lattice modes, which have not reported so far.

  7. Dielectric tensor of a weakly relativistic, nonequilibrium, and magnetized plasma

    NASA Technical Reports Server (NTRS)

    Tsai, S. T.; Wu, C. S.; Wang, Y. D.; Kang, S. W.

    1981-01-01

    The dielectric tensor of a magnetized plasma is investigated in order to obtain analytic expressions which can be used to study wave-plasma interactions for the case of wave frequencies lying close to the cyclotron harmonics of ions or electrons. Work on this topic by Trubnikov (1959) and Shkarovsky (1966) is extended to the nonequilibrium cases, in which the particles may have drift motions, thermal anisotropy, and loss-cone-type distributions. Account is taken of these features, and a set of analytic expressions in terms of an integral is derived. The discussion presented is pertinent to the absorption and emission of radiation near the electron cyclotron harmonics.

  8. Electrostatic solitary waves in a magnetized dusty plasma

    SciTech Connect

    Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.; Pillay, S. R.

    2008-11-15

    The nonlinear evolution of driven low-frequency electrostatic waves is investigated in a three-component magnetized dusty plasma comprised of a warm dust fluid, electrons, and ions. Electrons as well as ions are considered to have Boltzmann distributions. The fluid equations for the dust along with the quasineutrality condition are used to obtain a single nonlinear differential equation for the electric field. Periodic solutions of the nonlinear differential equation yield sinusoidal, sawtooth and bipolar structures which are similar to nonlinear structures supported in electron-ion plasmas. Results of our findings are applied to Saturn's rings.

  9. Beam transport with magnetic solenoids and plasma lenses

    SciTech Connect

    Noble, R.J.

    1988-10-01

    We examine the behavior of axisymmetric space-charge dominated beams in transport lines using numerical simulation. A typical transport line consisting of two axisymmetric linear lenses used to make a continuous beam from an ion source to a radio frequency quadrupole (RFQ) is considered. We compare the beam evolution when both lenses are magnetic solenoids or Gabor plasma lenses for beams with different initial density profiles. Emittance oscillations due to nonlinear space-charge forces by the action of plasma lenses in which space-charge fields are shielded, but beam mismatch at the RFQ entrance can be significant for both types of lens. 8 refs., 6 figs.

  10. A transverse Kelvin-Helmholtz instability in a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Kintner, P.; Dangelo, N.

    1977-01-01

    An analysis is conducted of the transverse Kelvin-Helmholtz instability in a magnetized plasma for unstable flute modes. The analysis makes use of a two-fluid model. Details regarding the instability calculation are discussed, taking into account the ion continuity and momentum equations, the solution of a zero-order and a first-order component, and the properties of the solution. It is expected that the linear calculation conducted will apply to situations in which the plasma has experienced no more than a few growth periods.

  11. Structure of a magnetic flux annihilation layer formed by the collision of supersonic, magnetized plasma flows

    SciTech Connect

    Suttle, L. G.; Hare, J. D.; Lebedev, S. V.; Swadling, G. F.; Burdiak, G. C.; Ciardi, A.; Chittenden, J. P.; Loureiro, N. F.; Niasse, N.; Suzuki-Vidal, F.; Wu, J.; Yang, Q.; Clayson, T.; Frank, A.; Robinson, T. S.; Smith, R. A.; Stuart, N.

    2016-05-31

    We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counter-streaming, supersonic and magnetized aluminum plasma flows. The anti parallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure—two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (Ti~¯ZTe, with average ionization ¯Z=7). Lastly, analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of the in-flowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities.

  12. Structure of a magnetic flux annihilation layer formed by the collision of supersonic, magnetized plasma flows

    DOE PAGES

    Suttle, L. G.; Hare, J. D.; Lebedev, S. V.; ...

    2016-05-31

    We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counter-streaming, supersonic and magnetized aluminum plasma flows. The anti parallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure—two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (Ti~¯ZTe, with average ionization ¯Z=7). Lastly, analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of themore » in-flowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities.« less

  13. Structure of a Magnetic Flux Annihilation Layer Formed by the Collision of Supersonic, Magnetized Plasma Flows.

    PubMed

    Suttle, L G; Hare, J D; Lebedev, S V; Swadling, G F; Burdiak, G C; Ciardi, A; Chittenden, J P; Loureiro, N F; Niasse, N; Suzuki-Vidal, F; Wu, J; Yang, Q; Clayson, T; Frank, A; Robinson, T S; Smith, R A; Stuart, N

    2016-06-03

    We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counterstreaming, supersonic and magnetized aluminum plasma flows. The antiparallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure-two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (T_{i}∼Z[over ¯]T_{e}, with average ionization Z[over ¯]=7). Analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of the inflowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities.

  14. Optimal design of a new multipole bilayer magnetorheological brake

    NASA Astrophysics Data System (ADS)

    Shiao, Yaojung; Ngoc, Nguyen Anh; Lai, Chien-Hung

    2016-11-01

    This article presents a new high-torque multipole bilayer magneto-rheological brake (MRB). This MRB has a unique structural design with multiple electromagnetic poles and multiple media layers of magnetorheological fluid (MRF). The MRB has two rotors located on the outer and inner sides of a six-pole stator, and therefore, it can provide higher torque and a larger torque-to-volume ratio (TVR) than conventional single- or multipole single-layer MRBs can. Moreover, the problem of potential MRF leakage is solved by using cylindrical separator rings around the stator. In this study, first, the structure of the proposed MRB is introduced. An analog magnetic circuit was built for the MRB to investigate the effects of the MRB parameters on the magnetic field intensity of the MRF layers. In addition, a 3D electromagnetic model of the MRB was developed to simulate and examine the magnetic flux intensity and corresponding braking torque. An approximate optimization method was then applied to obtain the optimal geometric dimensions for the major dimensional parameters of the MRB. The MRB was manufactured and tested to validate its torque and dynamic characteristics. The results showed that the proposed MRB exhibited great enhancement of the braking torque and TVR.

  15. Toward the Theory of Turbulence in Magnetized Plasmas

    SciTech Connect

    Boldyrev, Stanislav

    2013-07-26

    The goal of the project was to develop a theory of turbulence in magnetized plasmas at large scales, that is, scales larger than the characteristic plasma microscales (ion gyroscale, ion inertial scale, etc.). Collisions of counter-propagating Alfven packets govern the turbulent cascade of energy toward small scales. It has been established that such an energy cascade is intrinsically anisotropic, in that it predominantly supplies energy to the modes with mostly field-perpendicular wave numbers. The resulting energy spectrum of MHD turbulence, and the structure of the fluctuations were studied both analytically and numerically. A new parallel numerical code was developed for simulating reduced MHD equations driven by an external force. The numerical setting was proposed, where the spectral properties of the force could be varied in order to simulate either strong or weak turbulent regimes. It has been found both analytically and numerically that weak MHD turbulence spontaneously generates a “condensate”, that is, concentration of magnetic and kinetic energy at small k{sub {parallel}}. A related topic that was addressed in the project is turbulent dynamo action, that is, generation of magnetic field in a turbulent flow. We were specifically concentrated on the generation of large-scale magnetic field compared to the scales of the turbulent velocity field. We investigate magnetic field amplification in a turbulent velocity field with nonzero helicity, in the framework of the kinematic Kazantsev-Kraichnan model.

  16. Magnetic-Nozzle Studies for Fusion Propulsion Applications: Gigawatt Plasma Source Operation and Magnetic Nozzle Analysis

    NASA Technical Reports Server (NTRS)

    Gilland, James H.; Mikekkides, Ioannis; Mikellides, Pavlos; Gregorek, Gerald; Marriott, Darin

    2004-01-01

    This project has been a multiyear effort to assess the feasibility of a key process inherent to virtually all fusion propulsion concepts: the expansion of a fusion-grade plasma through a diverging magnetic field. Current fusion energy research touches on this process only indirectly through studies of plasma divertors designed to remove the fusion products from a reactor. This project was aimed at directly addressing propulsion system issues, without the expense of constructing a fusion reactor. Instead, the program designed, constructed, and operated a facility suitable for simulating fusion reactor grade edge plasmas, and to examine their expansion in an expanding magnetic nozzle. The approach was to create and accelerate a dense (up to l0(exp 20)/m) plasma, stagnate it in a converging magnetic field to convert kinetic energy to thermal energy, and examine the subsequent expansion of the hot (100's eV) plasma in a subsequent magnetic nozzle. Throughout the project, there has been a parallel effort between theoretical and numerical design and modelling of the experiment and the experiment itself. In particular, the MACH2 code was used to design and predict the performance of the magnetoplasmadynamic (MPD) plasma accelerator, and to design and predict the design and expected behavior for the magnetic field coils that could be added later. Progress to date includes the theoretical accelerator design and construction, development of the power and vacuum systems to accommodate the powers and mass flow rates of interest to out research, operation of the accelerator and comparison to theoretical predictions, and computational analysis of future magnetic field coils and the expected performance of an integrated source-nozzle experiment.

  17. Length of magnetic field lines in turbulent plasmas.

    PubMed

    Nunez, Manuel

    2002-06-01

    An estimation of the length of any magnetic field line in a two-dimensional periodic magnetohydrodynamic problem is provided. This is done by using some classical function theory results on the analytic extension of the vector potential. The essential parameter, the maximum of this extension, may be analyzed in the case of turbulent plasmas by admitting the Iroshnikov-Kraichnan statistics, establishing in this way a relation between the length of any magnetic field line and the energy dissipation scale. (c) 2002 American Institute of Physics.

  18. Electron-positron pair equilibrium in strongly magnetized plasmas

    SciTech Connect

    Harding, A.K.

    1984-11-01

    Steady states of thermal electron-positron pair plasmas at mildly relativistic temperatures and in strong magnetic fields are investigated. The pair density in steady-state equilibrium, where pair production balances annihilation, is found as a function of temperature, magnetic field strength and source size, by a numerical calculation which includes pair production attenuation and Compton scattering of the photons. It is found that there is a maximum pair density for each value of temperature and field strength, and also a source size above which optically thin equilibrium states do not exist. (ESA)

  19. Evolution of chirped laser pulses in a magnetized plasma channel

    SciTech Connect

    Jha, Pallavi; Hemlata,; Mishra, Rohit Kumar

    2014-12-15

    The propagation of intense, short, sinusoidal laser pulses in a magnetized plasma channel has been studied. The wave equation governing the evolution of the radiation field is set up and a variational technique is used to obtain the equations describing the evolution of the laser spot size, pulse length and chirp parameter. Numerical methods are used to analyze the simultaneous evolution of these parameters. The effect of the external magnetic field on initially chirped as well as unchirped laser pulses on the spot size, pulse length and chirping has been analyzed.

  20. Multi-ion Double Layers in a Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Shahmansouri, M.; Alinejad, H.; Tribeche, M.

    2015-11-01

    A theoretical investigation is carried out to study the existence, formation and basic properties of ion acoustic (IA) double layers (DLs) in a magnetized bi-ion plasma consisting of warm/cold ions and Boltzmann distributed electrons. Based on the reductive perturbation technique, an extended Korteweg de-Vries (KdV) equation is derived. The propagation of two possible modes (fast and slow), and their evolution are investigated. The effects of obliqueness, magnitude of the magnetic field, ion concentration, polarity of ions, and ion temperature on the IA DL profile are analyzed, and then the ranges of parameters for which the IA DLs exist are investigated in details.

  1. Study of Magnetic Reconnection in Plasma: how it works and energizes plasma particles

    NASA Astrophysics Data System (ADS)

    Yamada, Masaaki

    2015-11-01

    Magnetic reconnection is a phenomenon of nature in which magnetic field lines change their topology in plasma and convert magnetic energy to plasma particles by acceleration and heating. It is a fundamental process at work in laboratory, space and astrophysical plasmas. Magnetic reconnection occurs throughout the Universe: in star forming galaxies; around supernovae; in solar flares; in the earth's magnetosphere; and in fusion plasmas. One of the great challenges in reconnection research has been to understand why reconnection occurs so much faster than predicted by MHD theory. This talk begins with a review of recent discoveries and findings in the research of fast magnetic reconnection in laboratory plasmas and space astrophysical plasmas. I compare the experimental results and space observations with theory and numerical simulations. The collaboration between space and laboratory scientists in reconnection research has reached a point where we can directly compare measurements of the reconnection layer using recently-advanced numerical simulations. In spite of the huge difference in physical scales, we find remarkable commonality between the characteristics of the magnetic reconnection in laboratory and space-astrophysical plasmas. In this talk, I will focus especially on the energy flow, a key feature of reconnection process. We have recently reported our results on the energy conversion and partitioning in a laboratory reconnection layer. In Magnetic Reconnection Experiment (MRX) the mechanisms of ion acceleration and heating are identified and a systematic study of the quantitative inventory of converted energy within a reconnection layer has been made with a well-defined but variable boundary. The measured energy partition in a reconnection region of similar effective size (L ~ 3 ion skin depth) of the Earth's magneto-tail is remarkably consistent with the laboratory results. A more comprehensive study is proposed using MMS satellites very recently put into

  2. Design of a Compact Coaxial Magnetized Plasma Gun for Magnetic Bubble Expansion Experiments

    DTIC Science & Technology

    2009-06-01

    magnetic bubble expansion into a lower pressure background plasma as a laboratory model for extragalactic radio lobe expansion into the interstellar...control system, bias flux cap-bank power system, and experimental data are provided. I. INTRODUCTION Astrophysical radio lobe structures...jet’s radio lobe structures. Outstanding plasma physics issues regarding astrophysical jets and radio lobes include (ⅰ) the nature of radio lobe

  3. Vlasov simulations of plasma-wall interactions in a magnetized and weakly collisional plasma

    SciTech Connect

    Devaux, S.; Manfredi, G.

    2006-08-15

    A Vlasov code is used to model the transition region between an equilibrium plasma and an absorbing wall in the presence of a tilted magnetic field, for the case of a weakly collisional plasma ({lambda}{sub mfp}>>{rho}{sub i}, where {lambda}{sub mfp} is the ion-neutral mean-free path and {rho}{sub i} is the ion Larmor radius). The phase space structure of the plasma-wall transition is analyzed in detail and theoretical estimates of the magnetic presheath width are tested numerically. It is shown that the distribution near the wall is far from Maxwellian, so that temperature measurements should be interpreted with care. Particular attention is devoted to the angular distribution of ions impinging on the wall, which is an important parameter to determine the level of wall erosion and sputtering.

  4. Collisional relaxation of bi-Maxwellian plasma temperatures in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Yoon, Peter H.

    2016-07-01

    In the literature, collisional processes are customarily discussed within the context of the Boltzmann-Balescu-Lenard-Landau type of collision integral, but such an equation is strictly valid for unmagnetized plasmas. For plasmas immersed in the ambient magnetic field, the foundational equation that describes binary collisions must be generalized to include the effects of magnetic field. The present paper makes use of such an equation in order to describe the collisional relaxation of temperatures under the assumption of bi-Maxwellian velocity distribution function. The formalism derived in the present paper may be useful for studying the effects of binary collisions on the isotropization of temperatures in the solar wind plasma, among possible applications.

  5. New mode of operating a magnetized coaxial plasma gun for injecting magnetic helicity into a spheromak.

    PubMed

    Woodruff, S; Hill, D N; Stallard, B W; Bulmer, R; Cohen, B; Holcomb, C T; Hooper, E B; McLean, H S; Moller, J; Wood, R D

    2003-03-07

    By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (approximately 1 kV) are produced, giving the highest sustained voltage approximately 500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B/B>/=2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments.

  6. Suppressing CMB low multipoles with ISW effect

    SciTech Connect

    Das, Santanu; Souradeep, Tarun E-mail: tarun@iucaa.ernet.in

    2014-02-01

    Recent results of Planck data reveal that the power [1,2] in the low multipoles of the CMB angular power spectrum, approximately up to l = 30, is significantly lower than the theoretically predicted in the best fit ΛCDM model. There are different known physical effects that can affect the power at low multipoles, such as features in the primordial power spectrum (PPS) in some models of inflation and ISW effect. In this paper we investigate the possibility of invoking the Integrated Sachs-Wolfe (ISW) effect to explain the power deficit at low multipoles. The ISW effect that originates from the late time expansion history of the universe is rich in possibilities given the limited understanding of the origin of dark energy (DE). It is a common understanding that the ISW effect adds to the power at the low multipoles of the CMB angular power spectrum. In this paper we carry out an analytic study to show that there are some expansion histories in which the ISW effect, instead of adding power, provides negative contribution to the power at low multipoles. Guided by the analytic study, we present examples of the features required in the late time expansion history of the universe that could explain the power deficiency through the ISW effect. We also show that an ISW origin of power deficiency is consistent, at present, with other cosmological observations that probe the expansion history such as distance modulus, matter power spectrum and the evolution of cluster number count. We also show that the ISW effect may be distinguished from power deficit originating from features in the PPS using the measurements of the CMB polarization spectrum at low multipoles expected from Planck. We conclude that the power at low multipoles of the CMB anisotropy could well be closely linked to Dark Energy puzzle in cosmology and this observation could be actually pointing to richer phenomenology of DE beyond the cosmological constant Λ.

  7. Scaling of Magnetic Reconnection in Relativistic Collisionless Pair Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, Yi-Hsin; Guo, Fan; Daughton, William; Li, Hui; Hesse, Michael

    2015-01-01

    Using fully kinetic simulations, we study the scaling of the inflow speed of collisionless magnetic reconnection in electron-positron plasmas from the non-relativistic to ultra-relativistic limit. In the anti-parallel configuration, the inflow speed increases with the upstream magnetization parameter sigma and approaches the speed of light when sigma is greater than O(100), leading to an enhanced reconnection rate. In all regimes, the divergence of the pressure tensor is the dominant term responsible for breaking the frozen-in condition at the x-line. The observed scaling agrees well with a simple model that accounts for the Lorentz contraction of the plasma passing through the diffusion region. The results demonstrate that the aspect ratio of the diffusion region, modified by the compression factor of proper density, remains approximately 0.1 in both the non-relativistic and relativistic limits.

  8. Dressed ion-acoustic solitons in magnetized dusty plasmas

    NASA Astrophysics Data System (ADS)

    El-Labany, S. K.; El-Shamy, E. F.; El-Warraki, S. A.

    2009-01-01

    In the present research paper, the characteristics of ion acoustic solitary waves are investigated in hot magnetized dusty plasmas consisting of negatively charged dust grains, positively charged ion fluid, and isothermal electrons. Applying a reductive perturbation theory, a nonlinear Korteweg-de Vries (KdV) equation for the first-order perturbed potential and a linear inhomogeneous KdV-type equation for the second-order perturbed potentials are derived. Stationary solutions of these coupled equations are obtained using a renormalization method. The effects of the external oblique magnetic field, hot ion fluid, and higher-order nonlinearity on the nature of the ion acoustic solitary waves are discussed. The results complement and provide new insights into previously published results on this problem [R. S. Tiwari and M. K. Mishra, Phys. Plasmas 13, 062112 (2006)].

  9. Low frequency nonlinear waves in electron depleted magnetized nonthermal plasmas

    NASA Astrophysics Data System (ADS)

    Mobarak Hossen, Md.; Sahadat Alam, Md.; Sultana, Sharmin; Mamun, A. A.

    2016-11-01

    A theoretical study on the ultra-low frequency small but finite amplitude solitary waves has been carried out in an electron depleted magnetized nonthermal dusty plasma consisting of both polarity (positively charged as well as negatively charged) inertial massive dust particles and nonextensive q distributed ions. The reductive perturbation technique is employed to derive the ZakharovKuznetsov (ZK) equation. The basic features of low frequency solitary wave are analyzed via the solution of ZK equation. It is observed that the intrinsic properties (e.g., polarity, amplitude, width, etc.) of dust-acoustic (DA) solitary waves (SWs) are significantly influenced by the effects external magnetic field, obliqueness, nonextensivity of ions, and the ratio of ion number density to the product of electron and negative dust number density. The findings of our results may be useful to explain the low frequency nonlinear wave propagation in some plasma environments like cometary tails, the earth polar mesosphere, Jupiter's magnetosphere, etc.

  10. Exchange interaction effects on waves in magnetized quantum plasmas

    SciTech Connect

    Trukhanova, Mariya Iv. Andreev, Pavel A.

    2015-02-15

    We have applied the many-particle quantum hydrodynamics that includes the Coulomb exchange interaction to magnetized quantum plasmas. We considered a number of wave phenomena that are affected by the Coulomb exchange interaction. Since the Coulomb exchange interaction affects the longitudinal and transverse-longitudinal waves, we focused our attention on the Langmuir waves, the Trivelpiece-Gould waves, the ion-acoustic waves in non-isothermal magnetized plasmas, the dispersion of the longitudinal low-frequency ion-acoustic waves, and low-frequency electromagnetic waves at T{sub e} ≫ T{sub i}. We have studied the dispersion of these waves and present the numeric simulation of their dispersion properties.

  11. Magnetic-Field Generation and Amplification in an Expanding Plasma

    NASA Astrophysics Data System (ADS)

    Schoeffler, K. M.; Loureiro, N. F.; Fonseca, R. A.; Silva, L. O.

    2014-05-01

    Particle-in-cell simulations are used to investigate the formation of magnetic fields B in plasmas with perpendicular electron density and temperature gradients. For system sizes L comparable to the ion skin depth di, it is shown that B˜di/L, consistent with the Biermann battery effect. However, for large L/di, it is found that the Weibel instability (due to electron temperature anisotropy) supersedes the Biermann battery as the main producer of B. The Weibel-produced fields saturate at a finite amplitude (plasma β≈100), independent of L. The magnetic energy spectra below the electron Larmor radius scale are well fitted by the power law with slope -16/3, as predicted by Schekochihin et al. [Astrophys. J. Suppl. Ser. 182, 310 (2009)].

  12. Relativistic magnetic reconnection driven by intense lasers in preformed plasma

    NASA Astrophysics Data System (ADS)

    Campbell, Paul; Raymond, A.; McKelvey, A.; Maksimchuk, A.; Nees, J.; Yanovsky, V.; Krushelnick, K.; Dong, C. F.; Fox, W.; Zulick, C.; Wei, M. S.; Chen, H.; Chvykov, V.; Mileham, C.; Nilson, P. M.; Stoeckl, C.; Thomas, A. G. R.; Willingale, L.

    2016-10-01

    Experiments were performed with the OMEGA EP laser system focusing the two short pulse beams to high intensities on foil targets. Relativistic electrons drive fast reconnection self-generated magnetic fields. To investigate the effects of a preformed plasma on this relativistic magnetic reconnection, a long pulse UV beam was used to ablate the front surface of layered targets. The density and reconnection dynamics in the preformed copper or CH plasma were diagnosed with a 4 ω optical probe. A spherically bent crystal imaged characteristic copper Kα emission induced by fast electrons accelerated into the target in the reconnection diffusion region. This work was supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0002727.

  13. Superfluorescence from dense electron hole plasmas under high magnetic fields

    NASA Astrophysics Data System (ADS)

    Jho, Y. D.; Wang, X.; Kono, J.; Reitze, D. H.; Wei, X.; Belyanin, A. A.; Kocharovsky, V. V.; Kocharovsky, Vl. V.; Solomon, G. S.

    Ultrafast optical excitation of a dense electron hole plasma in InxGa1-xAs multiple quantum wells in high magnetic fields (>20T) produces cooperative radiative recombination between conduction and valence band Landau levels (LL). Above a critical threshold, the emission is characterized by very narrow LL line widths, superlinear increase with increasing field and laser excitation fluence, and stochastic directionality from shot to shot. Here, we investigate the effects of temperature and excitation geometry on the emission properties.

  14. Currents between tethered electrodes in a magnetized laboratory plasma

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.; Urrutia, J. M.

    1989-01-01

    Laboratory experiments on important plasma physics issues of electrodynamic tethers were performed. These included current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The experiments were conducted in a large afterglow plasma. The current system was established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential difference up to V approx.=100 T(sub e). The total current density in space and time was obtained from complete measurements of the perturbed magnetic field. The fast spacecraft motion was reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generally accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects. The implications of the laboratory observations on electrodynamic tethers in space are discussed.

  15. Electrostatic acceleration of helicon plasma using a cusped magnetic field

    SciTech Connect

    Harada, S.; Baba, T.; Uchigashima, A.; Iwakawa, A.; Sasoh, A.; Yokota, S.; Yamazaki, T.; Shimizu, H.

    2014-11-10

    The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in the field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion.

  16. Dust Particle Dynamics in The Presence of Highly Magnetized Plasmas

    NASA Astrophysics Data System (ADS)

    Lynch, Brian; Konopka, Uwe; Thomas, Edward; Merlino, Robert; Rosenberg, Marlene

    2016-10-01

    Complex plasmas are four component plasmas that contain, in addition to the usual electrons, ions, and neutral atoms, macroscopic electrically charged (nanometer to micrometer) sized ``dust'' particles. These macroscopic particles typically obtain a net negative charge due to the higher mobility of electrons compared to that of ions. Because the electrons, ions, and dust particles are charged, their dynamics may be significantly modified by the presence of electric and magnetic fields. Possible consequences of this modification may be the charging rate and the equilibrium charge. For example, in the presence of a strong horizontal magnetic field (B >1 Tesla), it may be possible to observe dust particle gx B deflection and, from that deflection, determine the dust grain charge. In this poster, we present recent data from performing multiple particle dropping experiments to characterize the g x B deflection in the Magnetized Dusty Plasma Experiment (MDPX). This work is supported by funding from the U. S. Department of Energy Grant Number DE - SC0010485 and the NASA/Jet Propulsion Laboratory, JPL-1543114.

  17. On the Boltzmann relation in a cold magnetized plasma

    SciTech Connect

    Nasi, L.; Raimbault, J.-L.

    2010-11-15

    A systematic and exact comparison between the forces acting on magnetized electrons in a current-free plasma is considered within a fluid model. We show that the Boltzmann relation is fulfilled in the drift-diffusion approximation when (h{sub i}/h{sub e})(1+h{sub e}{sup 2})/(1+h{sub i}{sup 2})<<1 where h{sub e} (or h{sub i}) is the ratio of the electron (or ion) cyclotron to the collision frequency. When the nonlinear inertia terms are taken into account, the previous criterion is too rough and must be modified. In particular it is proved that the Boltzmann relation is not uniformly valid in the plasma. The case of bounded plasmas where the electron temperature must be determined self-consistently is discussed in detail.

  18. Fast Magnetic Reconnection: Bridging Laboratory and Space Plasma Physics

    SciTech Connect

    Bhattacharjee, Amitava

    2012-02-16

    Recent developments in experimental and theoretical studies of magnetic reconnection hold promise for providing solutions to outstanding problems in laboratory and space plasma physics. Examples include sawtooth crashes in tokamaks, substorms in the Earth’s Magnetosphere, eruptive solar flares, and more recently, fast reconnection in laser-produced high energy density plasmas. In each of these examples, a common and long-standing challenge has been to explain why fast reconnection proceeds rapidly from a relatively quiescent state. In this talk, we demonstrate the advantages of viewing these problems and their solutions from a common perspective. We focus on some recent, surprising discoveries regarding the role of secondary plasmoid instabilities of thin current sheets. Nonlinearly, these instabilities lead to fast reconnection rates that are very weakly dependent on the Lundquist number of the plasma.

  19. Magnetic field generation, Weibel-mediated collisionless shocks, and magnetic reconnection in colliding laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fox, William

    2015-08-01

    Colliding plasmas are ubiquitous in astrophysical environments and allow conversion of kinetic energy into heat and, most importantly, the acceleration of particles to extremely high energies to form the cosmic ray spectrum. In collisionless astrophysical plasmas, kinetic plasma processes govern the interaction and particle acceleration processes, including shock formation, self-generation of magnetic fields by kinetic plasma instabilities, and magnetic field compression and reconnection. How each of these contribute to the observed spectra of cosmic rays is not fully understood, in particular both shock acceleration processes and magnetic reconnection have been proposed. We will review recent results of laboratory astrophysics experiments conducted at high-power, inertial-fusion-class laser facilities, which have uncovered significant results relevant to these processes. Recent experiments have now observed the long-sought Weibel instability between two interpenetrating high temperature plasma plumes, which has been proposed to generate the magnetic field necessary for shock formation in unmagnetized regimes. A second set of experiments has demonstrated magnetized shock formation in pre-magnetized plasmas. Finally, magnetic reconnection has been studied in systems of colliding plasmas using either self-generated magnetic fields or externally applied magnetic fields, and show extremely fast reconnection rates, indicating fast destruction of magnetic energy and further possibilities to accelerate particles. Finally, we highlight kinetic plasma simulations, which have proven to be essential tools in the design and interpretation of these experiments.

  20. Plasma cleaning of ITER First Mirrors in magnetic field

    NASA Astrophysics Data System (ADS)

    Moser, Lucas; Steiner, Roland; Leipold, Frank; Reichle, Roger; Marot, Laurent; Meyer, Ernst

    2015-08-01

    To avoid reflectivity losses in ITER's optical diagnostic systems, plasma sputtering of metallic First Mirrors is foreseen in order to remove deposits coming from the main wall (mainly beryllium and tungsten). Therefore plasma cleaning has to work on large mirrors (up to a size of 200 × 300 mm) and under the influence of strong magnetic fields (several Tesla). This work presents the results of plasma cleaning of aluminium and aluminium oxide (used as beryllium proxy) deposited on molybdenum mirrors. Using radio frequency (13.56 MHz) argon plasma, the removal of a 260 nm mixed aluminium/aluminium oxide film deposited by magnetron sputtering on a mirror (98 mm diameter) was demonstrated. 50 nm of pure aluminium oxide were removed from test mirrors (25 mm diameter) in a magnetic field of 0.35 T for various angles between the field lines and the mirrors surfaces. The cleaning efficiency was evaluated by performing reflectivity measurements, Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy.

  1. Thermodynamic Study on Plasma Expansion along a Divergent Magnetic Field.

    PubMed

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2016-01-15

    Thermodynamic properties are revisited for electrons that are governed by nonlocal electron energy probability functions in a plasma of low collisionality. Measurements in a laboratory helicon double layer experiment have shown that the effective electron temperature and density show a polytropic correlation with an index of γ_{e}=1.17±0.02 along the divergent magnetic field, implying a nearly isothermal plasma (γ_{e}=1) with heat being brought into the system. However, the evolution of electrons along the divergent magnetic field is essentially an adiabatic process, which should have a γ_{e}=5/3. The reason for this apparent contradiction is that the nearly collisionless plasma is very far from local thermodynamic equilibrium and the electrons behave nonlocally. The corresponding effective electron enthalpy has a conservation relation with the potential energy, which verifies that there is no heat transferred into the system during the electron evolution. The electrons are shown in nonlocal momentum equilibrium under the electric field and the gradient of the effective electron pressure. The convective momentum of ions, which can be assumed as a cold species, is determined by the effective electron pressure and the effective electron enthalpy is shown to be the source for ion acceleration. For these nearly collisionless plasmas, the use of traditional thermodynamic concepts can lead to very erroneous conclusions regarding the thermal conductivity.

  2. Lunar Swirls: Plasma Magnetic Field Interaction and Dust Transport

    NASA Astrophysics Data System (ADS)

    Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin; Hyde, Truell

    2013-10-01

    In close collaboration between the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, and the Institute of Space Systems (IRS) at the University of Stuttgart, Germany, two plasma facilities have been established using the Inductively heated Plasma Generator 6 (IPG6), based on proven IRS designs. A wide range of applications is currently under consideration for both test and research facilities. Basic investigations in the area of plasma radiation and catalysis, simulation of certain parameters of fusion divertors and space applications are planned. In this paper, the facility at Baylor University (IPG6-B) will be used for simulation of mini-magnetospheres on the Moon. The interaction of the solar wind with magnetic fields leads to the formation of electric fields, which can influence the incoming solar wind ion flux and affect dust transport processes on the lunar surface. Both effects may be partially responsible for the occurrence of lunar swirls. Interactions of the solar wind with such mini-magnetospheres will be simulated in the IPG6-B by observing the interaction between a plasma jet and a permanent magnet. The resulting data should lead to better models of dust transport processes and solar wind deflection on the moon.

  3. Thermal equilibrium of a cryogenic magnetized pure electron plasma

    NASA Technical Reports Server (NTRS)

    Dubin, D. H. E.; Oneil, T. M.

    1986-01-01

    The thermal equilibrium correlation properties of a magnetically confined pure electron plasma (McPEP) are related to those of a one-component plasma (OCP). The N-particle spatial distribution rho sub s and the Helmholtz free energy F are evaluated for the McPEP to O(lambda sub d-squared/a-squared), where lambda sub d is the thermal de Broglie wavelength and is an interparticle spacing. The electron gyromotion is allowed to be fully quantized while the guiding center motion is quasi-classical. The distribution rho sub s is shown to be identical to that of a classical OCP with a slightly modified potential. To O(lambda sub d-squared/a-squared) this modification does not affect that part of F that is caused by correlations, as long as certain requirements concerning the size of the plasma are met. This theory is motivated by a current series of experiments that involve the cooling of a magnetically confined pure electron plasma to the cryogenic temperature range.

  4. Mitigating Stimulated Raman Scattering in Hohlraum Plasmas Using Magnetic Insulation

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Albright, B. J.; Kline, J. L.; Yin, L.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.; MacDonald, M. J.

    2013-10-01

    Controlling stimulated Raman scattering (SRS) in hohlraum plasmas is important for achieving high-gain inertial fusion using indirect drive. Experiments at the National Ignition Facility (NIF) suggest that coronal electron temperatures in NIF hohlraums may be cooler than initially thought due to efficient thermal conduction from the under dense low-Z plasma to the dense high-Z hohlraum wall. This leads to weaker Landau damping and stronger growth of SRS. Magnetic insulation of the heat conducting electrons can occur when the Hall parameter ωceτei >> 1, where ωce is the electron-cyclotron frequency, and τei is the electron-ion collision time. For NIF laser-plasma conditions, it is shown that a 10-T external magnetic field may substantially reduce cross-field transport and may increase coronal plasma temperatures, thus increasing linear Landau damping and mitigating SRS. We will present calculations and simulations supporting this concept, and will present initial results from Omega experiments using gas-filled hohlraums with external B-fields up to 10-T. Work performed under the auspices of DOE by LANL under contract DE-AC52-06NA25396.

  5. Two density peaks in low magnetic field helicon plasma

    SciTech Connect

    Wang, Y.; Zhao, G.; Ouyang, J. T. E-mail: lppmchenqiang@hotmail.com; Liu, Z. W.; Chen, Q. E-mail: lppmchenqiang@hotmail.com

    2015-09-15

    In this paper, we report two density peaks in argon helicon plasma under an axial magnetic field from 0 G to 250 G with Boswell-type antenna driven by radio frequency (RF) power of 13.56 MHz. The first peak locates at 40–55 G and the second one at 110–165 G, as the RF power is sustainably increased from 100 W to 250 W at Ar pressure of 0.35 Pa. The absorbed power of two peaks shows a linear relationship with the magnetic field. End views of the discharge taken by intensified charge coupled device reveal that, when the first peak appeared, the discharge luminance moves to the edge of the tube as the magnetic field increases. For the second peak, the strong discharge area is centered at the two antenna legs after the magnetic field reaches a threshold value. Comparing with the simulation, we suggest that the efficient power absorption of two peaks at which the efficient power absorption mainly appears in the near-antenna region is due to the mode conversion in bounded non-uniform helicon plasma. The two low-field peaks are caused, to some extent, by the excitation of Trivelpiece-Gould wave through non-resonance conversion.

  6. Modelling of Divertor Plasma Transport in Stochastic Magnetic Boundary

    NASA Astrophysics Data System (ADS)

    Kobayashi, Masahiro

    2010-05-01

    Impacts of stochastic magnetic field structure on divertor functions are discussed based on analyses with the three dimensional (3D) edge transport code package EMC3-EIRENE with Braginskii type fluid equations, in the Large Helical Device (LHD), in comparison with the experimental data. It is shown that the three dimensional field line topology introduced by the stochasticity provides controllability of the edge plasma transport such as divertor regime, impurity transport. The observations in other devices with stochastic magnetic boundary regarding these issues are discussed as well. Also presented are the traditional formulation of the magnetic field and the transport in the stochastic layer based on diffusive picture, which are contrasted with the 3D treatment of the flux tube topology and of the transport.

  7. Hall MHD Stability and Turbulence in Magnetically Accelerated Plasmas

    SciTech Connect

    H. R. Strauss

    2012-11-27

    The object of the research was to develop theory and carry out simulations of the Z pinch and plasma opening switch (POS), and compare with experimental results. In the case of the Z pinch, there was experimental evidence of ion kinetic energy greatly in excess of the ion thermal energy. It was thought that this was perhaps due to fine scale turbulence. The simulations showed that the ion energy was predominantly laminar, not turbulent. Preliminary studies of a new Z pinch experiment with an axial magnetic field were carried out. The axial magnetic is relevant to magneto - inertial fusion. These studies indicate the axial magnetic field makes the Z pinch more turbulent. Results were also obtained on Hall magnetohydrodynamic instability of the POS.

  8. Magnetic apatite for structural insights on the plasma membrane.

    PubMed

    Stanca, Sarmiza E; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-21

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  9. Pulsating jet-like structures in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-01

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as "radio pulsars." The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  10. Magnetic apatite for structural insights on the plasma membrane

    NASA Astrophysics Data System (ADS)

    Stanca, Sarmiza E.; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-01

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  11. 3-D, Impulsive Magnetic Reconnection in a Laboratory Plasma (Invited)

    NASA Astrophysics Data System (ADS)

    Dorfman, S. E.; Ji, H.; Yamada, M.; Yoo, J.; Myers, C. E.; Roytershteyn, V.; Daughton, W. S.; Jara-Almonte, J.

    2013-12-01

    Magnetic reconnection is a fundamental plasma process involving the efficient conversion of magnetic field energy to plasma kinetic energy through changing field line topology. In many space and astrophysical systems, including the solar surface and the Earth's magnetotail, reconnection is not only fast, but also impulsive; in other words, a slow buildup phase is followed by a comparatively quick release of magnetic energy. An important question in the literature is if these examples of impulsive reconnection can be described by a two-dimensional model with no variation in the out-of-plane direction or if impulsive reconnection is fundamentally three-dimensional. Events observed on the Magnetic Reconnection Experiment (MRX) are characterized by large local gradients in the third direction and cannot be explained by 2-D models [1]. Detailed measurements show that the ejection of flux rope structures from the current sheet plays a key role in these events. By contrast, even though electromagnetic fluctuations in the lower hybrid frequency range are also observed concurrently with the impulsive behavior, they are not the key physics responsible. Furthermore, an important discrepancy in the layer width and force balance between the collisionless regime of MRX and kinetic simulations [2-4] persists when the fluctuations are small or absent, implying that they are not the cause of the wider electron layers observed in the experiment [5]. These wider layers may instead be due to the formation of flux ropes with a wide range of sizes; consistent with this hypothesis, flux rope signatures are observed down to the smallest scales resolved by the diagnostics. Finally, a qualitative, 3-D, two-fluid model is proposed to explain the observed disruptions. Many of the features observed in MRX including current disruptions [6], flux ropes [7], and electromagnetic fluctuations [8] have analogues in space observations. Thus, further detailed comparisons may enhance our understanding

  12. Identification of multi-modal plasma responses to applied magnetic perturbations using the plasma reluctance

    DOE PAGES

    Logan, Nikolas C.; Paz-Soldan, Carlos; Park, Jong-Kyu; ...

    2016-05-03

    Using the plasma reluctance, the Ideal Perturbed Equilibrium Code is able to efficiently identify the structure of multi-modal magnetic plasma response measurements and the corresponding impact on plasma performance in the DIII-D tokamak. Recent experiments demonstrated that multiple kink modes of comparable amplitudes can be driven by applied nonaxisymmetric fields with toroidal mode number n = 2. This multi-modal response is in good agreement with ideal magnetohydrodynamic models, but detailed decompositions presented here show that the mode structures are not fully described by either the least stable modes or the resonant plasma response. This paper identifies the measured response fieldsmore » as the first eigenmodes of the plasma reluctance, enabling clear diagnosis of the plasma modes and their impact on performance from external sensors. The reluctance shows, for example, how very stable modes compose a significant portion of the multi-modal plasma response field and that these stable modes drive significant resonant current. Finally, this work is an overview of the first experimental applications using the reluctance to interpret the measured response and relate it to multifaceted physics, aimed towards providing the foundation of understanding needed to optimize nonaxisymmetric fields for independent control of stability and transport.« less

  13. Identification of multi-modal plasma responses to applied magnetic perturbations using the plasma reluctance

    SciTech Connect

    Logan, Nikolas C.; Paz-Soldan, Carlos; Park, Jong-Kyu; Nazikian, Raffi

    2016-05-03

    Using the plasma reluctance, the Ideal Perturbed Equilibrium Code is able to efficiently identify the structure of multi-modal magnetic plasma response measurements and the corresponding impact on plasma performance in the DIII-D tokamak. Recent experiments demonstrated that multiple kink modes of comparable amplitudes can be driven by applied nonaxisymmetric fields with toroidal mode number n = 2. This multi-modal response is in good agreement with ideal magnetohydrodynamic models, but detailed decompositions presented here show that the mode structures are not fully described by either the least stable modes or the resonant plasma response. This paper identifies the measured response fields as the first eigenmodes of the plasma reluctance, enabling clear diagnosis of the plasma modes and their impact on performance from external sensors. The reluctance shows, for example, how very stable modes compose a significant portion of the multi-modal plasma response field and that these stable modes drive significant resonant current. Finally, this work is an overview of the first experimental applications using the reluctance to interpret the measured response and relate it to multifaceted physics, aimed towards providing the foundation of understanding needed to optimize nonaxisymmetric fields for independent control of stability and transport.

  14. Laboratory simulation of magnetic plasma arch eruptions on the Sun

    NASA Astrophysics Data System (ADS)

    Tripathi, Shreekrishna; Gekelman, W.

    2013-07-01

    Eruption of arched magnetoplasma structures is a fundamental process that drives solar energetic events on wide spatiotemporal scales in the solar atmosphere. The term arched magnetic flux rope (AMFR) is associated with such structures since they carry electrical current which generates a twisted magnetic structure. In the limit of a low electrical-current, the magnetic-field-line-twist becomes small and a magnetic flux rope resembles the structure of a magnetic flux tube. A laboratory plasma experiment has been constructed at UCLA which is capable of generating reproducible AMFR eruptions with a 0.5 Hz repetition rate and recording their spatiotemporal evolution using computer-controlled movable probes (n ~ 1013 cm-3, Te ~ 10 eV, L = 0.5 m, I = 100 A, B ~ 1 kG at footpoints). The experiment has been designed by careful scaling of the relevant solar plasma parameters and the boundary conditions can be controlled to simulate a variety of drive mechanisms that may exist on the Sun (e.g., mass flow vs current flow from the AMFR footpoints, slow vs fast buildup of the magnetic energy in the arch). The AMFR evolves in a large background magnetoplasma (n ~ 1012 cm-3, Te ~ 4 eV, B = 20-100 G). The relative magnitudes of the plasma parameters of the AMFR and the ambient magnetoplasma can be varied. Stereo images of the AMFR evolution are recorded by a fast CCD camera using a variety of pass-band filters. In this presentation, recent experimental results comparing a fast eruption (time scale t < 3. Alfven transit time in the arch) with a slow eruption (time scale t > 100. Alfven transit time in the arch) of the AMFR will be discussed. The highlights of the post-eruption AMFR are low frequency global kink mode oscillations (f ~ 200 kHz) that appear concurrently with high-frequency fast waves (f ~ 5 MHz) in the AMFR. References: (1) S. K. P. Tripathi and W. Gekelman, Phys. Rev. Lett. 105, 075005 (2010) (2) S. K. P. Tripathi and W. Gekelman, Solar Physics, Published online 8

  15. Relativistic many-body calculations of lifetimes, rates, and line strengths of multipole transitions between 3l-1 4l' states in Ni-like ions

    SciTech Connect

    Safronova, U I; Safronova, A S; Beiersdorfer, P

    2007-10-08

    Transition rates and line strengths are calculated for electric-multipole (E2 and E3) and magnetic-multipole (M1, M2, and M3) transitions between 3s{sup 2}3p{sup 6}3d{sup 10}, 3s{sup 2}3p{sup 6}3d{sup 9}4l, 3s{sup 2}3p{sup 5}3d{sup 10}4l, and 3s3p{sup 6}3d{sup 10}4l states (with 4l = 4s, 4p, 4d, and 4f) in Ni-like ions with the nuclear charges ranging from Z = 34 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded multipole matrix elements. Transition energies used in the calculation of line strengths and transition rates are from second-order RMBPT. Lifetimes of the 3s{sup 2}3p{sup 6}3d{sup 9}4s levels are given for Z = 34-100. Taking into account that calculations were performed in a very broad range of Z, most of the data are presented in graphs as Z-dependencies. The full set of data is given only for Ni-like W ion. In addition, we also give complete results for the 3d4s{sup 3}D{sub 2}-3d4s {sup 3}D{sub 1} magnetic-dipole transition, as the transition may be observed in future experiments, which measure both transition energies and radiative rates. These atomic data are important in the modeling of radiation spectra from Ni-like multiply-charged ions generated in electron beam ion trap experiments as well as for laboratory plasma diagnostics including fusion research.

  16. Mitigating Laser-Plasma Instabilities in Hohlraum Laser-Plasmas Using Magnetic Insulation

    NASA Astrophysics Data System (ADS)

    Montgomery, D. S.; Simakov, A.; Albright, B. J.; Yin, L.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.

    2012-10-01

    Controlling laser-plasma instabilities in hohlraum plasmas is important for achieving high-gain inertial fusion using indirect drive. Experiments at the National Ignition Facility (NIF) suggest that coronal electron temperatures in NIF hohlraums may be cooler than initially thought due to efficient thermal conduction from the under dense low-Z plasma to the dense high-Z hohlraum wall [1]. This leads to weaker Landau damping and stronger growth of parametric instabilities. For NIF laser-plasma conditions, it is shown that a 10-T external magnetic field may substantially reduce cross-field transport and may increase plasma temperatures, thus increasing linear Landau damping and mitigating parametric instabilities. Additional benefits may be realized since the hot electrons will be strongly magnetized and may be prevented from reaching the capsule or hohlraum walls. We will present calculations and simulations supporting this concept, and describe experimental plans to test the concept using gas-filled hohlraums at the Omega Laser Facility.[4pt] [1] M.D. Rosen et al., High Eng. Dens. Phys. 7, 180 (2011).

  17. 3-D MHD modeling and stability analysis of jet and spheromak plasmas launched into a magnetized plasma

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin; Zhang, Yue; Wallace, Ben; Gilmore, Mark; Manchester, Ward; Arge, C. Nick

    2016-10-01

    The Plasma Bubble Expansion Experiment (PBEX) at the University of New Mexico uses a coaxial plasma gun to launch jet and spheromak magnetic plasma configurations into the Helicon-Cathode (HelCat) plasma device. Plasma structures launched from the gun drag frozen-in magnetic flux into the background magnetic field of the chamber providing a rich set of dynamics to study magnetic turbulence, force-free magnetic spheromaks, and shocks. Preliminary modeling is presented using the highly-developed 3-D, MHD, BATS-R-US code developed at the University of Michigan. BATS-R-US employs an adaptive mesh refinement grid that enables the capture and resolution of shock structures and current sheets, and is particularly suited to model the parameter regime under investigation. CCD images and magnetic field data from the experiment suggest the stabilization of an m =1 kink mode trailing a plasma jet launched into a background magnetic field. Results from a linear stability code investigating the effect of shear-flow as a cause of this stabilization from magnetic tension forces on the jet will be presented. Initial analyses of a possible magnetic Rayleigh Taylor instability seen at the interface between launched spheromaks and their entraining background magnetic field will also be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  18. Specialty magnets

    SciTech Connect

    Halbach, K.

    1986-07-01

    A number of basic conceptual designs are explained for magnet systems that use permanent magnet materials. Included are iron free multipoles and hybrid magnets. Also appended is a discussion of the manufacturing process and magnetic properties of some permanent magnet materials. (LEW)

  19. Observation of molecular assisted recombination in the magnetized sheet plasma

    NASA Astrophysics Data System (ADS)

    Tonegawa, Akira; Ogawa, Hironori; Yazawa, Hiroyuki; Ono, Masataka; Kawamura, Kazutaka

    2003-10-01

    Molecular assisted recombination (MAR) with vibrational hydorogen molecular has been observed to enhance the reduction of ion particle flux in a high density magnetized sheet plasma device (TPDSHEET-IV). There are two main paths for MAR: (1) H2(v) + e=> H- + H (dissociated attachment) followed by H- + H+ =>H + H (mutual neutralization), and (2) H2(v) + A+ => (AH)+ + H (ion conversion) followed by (AH)+ + e => A + H (dissociative recombination) , where A+(A) is a hydrogen or an impurity ion (atom) existing in the plasma. The value of H+, H2+ and H3+ are observed in the mid-plane region with hot electron(Te= 10-15 eV) by a mass-analyzer. On the other hand, negative ions of hydrogen atom H- is localized in the circumference of existing cold electrons (Te= 3-5 eV) by a probe assisted laser photodetachment method. A small amount of secondary hydrogen gas puffing into a hydrogen plasma decreased gradually the density of H2+, H3+ and increased rapidly H- in the plasma, while the conventional radiation and three-body recombination (EIR) processes were disappeared. These results can be well explained by taking the MAR in the plasma into account.

  20. Magnetic properties of Co-Zr-B magnets produced by spark plasma sintering method

    SciTech Connect

    Saito, Tetsuji Akiyama, Tomoya

    2014-05-07

    Magnets of Co-Zr-B, one of the permanent magnetic compounds without rare-earth elements, were successfully produced by the spark plasma sintering method. The resultant Co-Zr-B magnets had high densities of 92%–96% and consisted mainly of the Co{sub x}Zr (x ≈ 5) phase. The coercivity of the Co-Zr-B magnets was highly dependent on the consolidation temperature and the boron content. The highest maximum energy product of 6.0 MGOe, with a remanence of 6.4 kG and the coercivity of 4.0 kOe, was achieved by the Co{sub 80}Zr{sub 18}B{sub 2} magnets consolidated at 873 K.

  1. Self-generated magnetic dipoles in weakly magnetized beam-plasma system.

    PubMed

    Jia, Qing; Mima, Kunioki; Cai, Hong-bo; Taguchi, Toshihiro; Nagatomo, Hideo; He, X T

    2015-02-01

    A self-generation mechanism of magnetic dipoles and the anomalous energy dissipation of fast electrons in a magnetized beam-plasma system are presented. Based on two-dimensional particle-in-cell simulations, it is found that the magnetic dipoles are self-organized and play important roles in the beam electron energy dissipation. These dipoles drift slowly in the direction of the return flow with a quasisteady velocity, which depends upon the magnetic amplitude of the dipole and the imposed external magnetic field. This dipole formation provides a mechanism for the anomalous energy dissipation of a relativistic electron beam, which would play an important role in collisionless shock and ion shock acceleration.

  2. Spectral Kinetic Simulation of the Ideal Multipole Resonance Probe

    NASA Astrophysics Data System (ADS)

    Gong, Junbo; Wilczek, Sebastian; Szeremley, Daniel; Oberrath, Jens; Eremin, Denis; Dobrygin, Wladislaw; Schilling, Christian; Friedrichs, Michael; Brinkmann, Ralf Peter

    2015-09-01

    The term Active Plasma Resonance Spectroscopy (APRS) denotes a class of diagnostic techniques which utilize the natural ability of plasmas to resonate on or near the electron plasma frequency ωpe: An RF signal in the GHz range is coupled into the plasma via an electric probe; the spectral response of the plasma is recorded, and a mathematical model is used to determine plasma parameters such as the electron density ne or the electron temperature Te. One particular realization of the method is the Multipole Resonance Probe (MRP). The ideal MRP is a geometrically simplified version of that probe; it consists of two dielectrically shielded, hemispherical electrodes to which the RF signal is applied. A particle-based numerical algorithm is described which enables a kinetic simulation of the interaction of the probe with the plasma. Similar to the well-known particle-in-cell (PIC), it contains of two modules, a particle pusher and a field solver. The Poisson solver determines, with the help of a truncated expansion into spherical harmonics, the new electric field at each particle position directly without invoking a numerical grid. The effort of the scheme scales linearly with the ensemble size N.

  3. Low pressure characteristics of the multipole resonance probe

    NASA Astrophysics Data System (ADS)

    Brinkmann, Ralf Peter; Oberrath, Jens

    2014-10-01

    The term ``Active plasma resonance spectroscopy'' (APRS) denotes a class of related techniques which utilize, for diagnostic purposes, the natural ability of plasmas to resonate on or near the electron plasma frequency ωpe. The basic idea dates back to the early days of discharge physics but has recently found renewed interest as an approach to industry-compatible plasma diagnostics: A radio frequent signal (in the GHz range) is coupled into the plasma via an antenna or probe, the spectral response is recorded (with the same or another antenna or probe), and a mathematical model is used to determine plasma parameters like the electron density or the electron temperature. When the method is applied to low pressure plasmas (of a few Pa and lower), kinetic effects must be accounted for in the mathematical model. This contribution studies a particular realization of the APRS scheme, the geometrically and electrically symmetric Multipole Resonance Probe (MRP). It is shown that the resonances of the MRP exhibit a residual damping in the limit p --> 0 which cannot be explained by Ohmic dissipation but only by kinetic effects. Supported by the German Federal Ministry of Education and Research (BMBF) in the framework of the PluTO project.

  4. Diagnosing laser-preheated magnetized plasmas relevant to magnetized liner inertial fusion

    SciTech Connect

    Harvey-Thompson, Adam James; Sefkow, Adam B.; Nagayama, Taisuke N.; Wei, Mingsheng; Campbell, Edward Michael; Fiksel, Gennady; Chang, Po -Yu; Davies, Jonathan R.; Barnak, Daniel H.; Glebov, Vladimir Y.; Fitzsimmons, Paul; Fooks, Julie; Blue, Brent E.

    2015-12-22

    In this paper, we present a platform on the OMEGA EP Laser Facility that creates and diagnoses the conditions present during the preheat stage of the MAGnetized Liner Inertial Fusion (MagLIF) concept. Experiments were conducted using 9 kJ of 3ω (355 nm) light to heat an underdense deuterium gas (electron density: 2.5 × 1020 cm-3 = 0.025 of critical density) magnetized with a 10 T axial field. Results show that the deuterium plasma reached a peak electron temperature of 670 ± 140 eV, diagnosed using streaked spectroscopy of an argon dopant. The results demonstrate that plasmas relevant to the preheat stage of MagLIF can be produced at multiple laser facilities, thereby enabling more rapid progress in understanding magnetized preheat. Results are compared with magneto-radiation-hydrodynamics simulations, and plans for future experiments are described.

  5. Diagnosing laser-preheated magnetized plasmas relevant to magnetized liner inertial fusion

    DOE PAGES

    Harvey-Thompson, Adam James; Sefkow, Adam B.; Nagayama, Taisuke N.; ...

    2015-12-22

    In this paper, we present a platform on the OMEGA EP Laser Facility that creates and diagnoses the conditions present during the preheat stage of the MAGnetized Liner Inertial Fusion (MagLIF) concept. Experiments were conducted using 9 kJ of 3ω (355 nm) light to heat an underdense deuterium gas (electron density: 2.5 × 1020 cm-3 = 0.025 of critical density) magnetized with a 10 T axial field. Results show that the deuterium plasma reached a peak electron temperature of 670 ± 140 eV, diagnosed using streaked spectroscopy of an argon dopant. The results demonstrate that plasmas relevant to the preheatmore » stage of MagLIF can be produced at multiple laser facilities, thereby enabling more rapid progress in understanding magnetized preheat. Results are compared with magneto-radiation-hydrodynamics simulations, and plans for future experiments are described.« less

  6. Characteristics of the surface plasma wave in a self-gravitating magnetized dusty plasma slab

    SciTech Connect

    Lee, Myoung-Jae; Jung, Young-Dae

    2015-11-15

    The dispersion properties of surface dust ion-acoustic waves in a self-gravitating magnetized dusty plasma slab are investigated. The dispersion relation is derived by using the low-frequency magnetized dusty dielectric function and the surface wave dispersion integral for the slab geometry. We find that the self-gravitating effect suppresses the frequency of surface dust ion-acoustic wave for the symmetric mode in the long wavelength regime, whereas it hardly changes the frequency for the anti-symmetric mode. As the slab thickness and the wave number increase, the surface wave frequency slowly decreases for the symmetric mode but increases significantly for the anti-symmetric mode. The influence of external magnetic field is also investigated in the case of symmetric mode. We find that the strength of the magnetic field enhances the frequency of the symmetric-mode of the surface plasma wave. The increase of magnetic field reduces the self-gravitational effect and thus the self-gravitating collapse may be suppressed and the stability of dusty objects in space is enhanced.

  7. Formation of collisionless shocks in magnetized plasma interaction with kinetic-scale obstacles

    NASA Astrophysics Data System (ADS)

    Cruz, F.; Alves, E. P.; Bamford, R. A.; Bingham, R.; Fonseca, R. A.; Silva, L. O.

    2017-02-01

    We investigate the formation of collisionless magnetized shocks triggered by the interaction between magnetized plasma flows and miniature-sized (order of plasma kinetic-scales) magnetic obstacles resorting to massively parallel, full particle-in-cell simulations, including the electron kinetics. The critical obstacle size to generate a compressed plasma region ahead of these objects is determined by independently varying the magnitude of the dipolar magnetic moment and the plasma magnetization. We find that the effective size of the obstacle depends on the relative orientation between the dipolar and plasma internal magnetic fields, and we show that this may be critical to form a shock in small-scale structures. We study the microphysics of the magnetopause in different magnetic field configurations in 2D and compare the results with full 3D simulations. Finally, we evaluate the parameter range where such miniature magnetized shocks can be explored in laboratory experiments.

  8. The Multipole Structure of Earth's STEP Signal

    NASA Technical Reports Server (NTRS)

    Nordtvedt, Kenneth

    2003-01-01

    If there is an interaction in physical law which differentially accelerates the test bodies in a STEP satellite, then the di.erent elements that compose the Earth will most likely have source strengths for this interaction which are not proportional to their mass densities. The rotational flattening of Earth and geographical irregularities of our planet's crust then produces a multipole structure for the Equivalence Principle violating force field which differs from the multipole structure of Earth's ordinary gravity field. Measuring these differences yields key information about the new interaction in physical law which is not attainable by solely measuring differences of test body accelerations.

  9. Magnetic helicity balance in the Sustained Spheromak Plasma Experiment

    NASA Astrophysics Data System (ADS)

    Stallard, B. W.; Hooper, E. B.; Woodruff, S.; Bulmer, R. H.; Hill, D. N.; McLean, H. S.; Wood, R. D.

    2003-07-01

    The magnetic helicity balance between the helicity input injected by a magnetized coaxial gun, the rate-of-change in plasma helicity content, and helicity dissipation in electrode sheaths and Ohmic losses have been examined in the Sustained Spheromak Plasma Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, and R. H. Bulmer, Nucl. Fusion 39, 863 (1999)]. Helicity is treated as a flux function in the mean-field approximation, allowing separation of helicity drive and losses between closed and open field volumes. For nearly sustained spheromak plasmas with low fluctuations, helicity balance analysis implies a decreasing transport of helicity from the gun input into the spheromak core at higher spheromak electron temperature. Long pulse discharges with continuously increasing helicity and larger fluctuations show higher helicity coupling from the edge to the spheromak core. The magnitude of the sheath voltage drop, inferred from cathode heating and a current threshold dependence of the gun voltage, shows that sheath losses are important and reduce the helicity injection efficiency in SSPX.

  10. Dynamics of a plasma expanding into a uniform magnetic field

    SciTech Connect

    Gisler, G.; Lemons, D.S. )

    1989-08-01

    A heuristic model of an energetic plasma expanding into an initially uniform magnetic field is presented. In this model the plasma is cylindrically shaped, perfectly diamagnetic, and allowed to expand freely in the direction of the magnetic field. It results in a time evolution of the cylindrical radius described by Airy functions and parameterized by the plasma {beta}. For instance, the maximum extent of the radius scales as {beta}{sup 1/3} while the maximum radial deceleration scales as {beta}{sup {minus}1/3}. Time evolution and scaling are compared both with other models and with two-dimensional electromagnetic particle simulations. A spherically symmetric model is also found to agree well with the simulations and results in simpler expressions for the maximum radius and maximum radial deceleration. The larger deceleration obtained in these models, as compared with models that ignore the axial expansion, would shift toward longer wavelengths the peak growth of the instability thought to be responsible for the field-aligned structures seen in the Active Magnetospheric Particle Tracer Explorers (AMPTE) magnetotail releases. {copyright} American Geophysical Union 1989

  11. Anomalous diffusion across the magnetic field-plasma boundary - The Porcupine artificial plasma jet

    NASA Astrophysics Data System (ADS)

    Mishin, E. V.; Kapitanov, V. Ia.; Treumann, R. A.

    1986-09-01

    Very fast magnetic field diffusion into the beam is required for observation of the nearly undisturbed penetration of the Porcupine's dense, fast and heavy ion beam into the magnetized ionospheric plasma after termination of the short adiabatic phase. The diffusion is presently attributed to a transverse electron drift current-driven electrostatic instability that is excited by the diamagnetic current flowing in the boundary layer between the injected beam and the ambient field. The anomalous collision frequencies turn out to be of the order of the local lower hybrid frequency in the dense Xe plasma. Since only a very small fraction of beam energy is dissipated in the diffusion process, no significant deceleration of the ion beam is observable.

  12. Pair production rates in mildly relativistic, magnetized plasmas

    NASA Technical Reports Server (NTRS)

    Burns, M. L.; Harding, A. K.

    1984-01-01

    Electron-positron pairs may be produced by either one or two photons in the presence of a strong magnetic field. In magnetized plasmas with temperatures kT approximately sq mc, both of these processes may be important and could be competitive. The rates of one-photon and two-photon pair production by photons with Maxwellian, thermal bremsstrahlung, thermal synchrotron and power law spectra are calculated as a function of temperature or power law index and field strength. This allows a comparison of the two rates and a determination of the conditions under which each process may be a significant source of pairs in astrophysical plasmas. It is found that for photon densities n(gamma) or = 10 to the 25th power/cu cm and magnetic field strengths B or = 10 to the 12th power G, one-photon pair production dominates at kT approximately sq mc for a Maxwellian, at kT approximately 2 sq mc for a thermal bremsstrahlung spectrum, at all temperatures for a thermal synchrotron spectrum, and for power law spectra with indices s approximately 4.

  13. Magnetic fields, plasmas, and coronal holes: The inner solar system

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1978-01-01

    In situ magnetic field and plasma observations within 1 AU which describe MDH stream flows and Alfvenic fluctuations, the latest theories of those phenomena are discussed. Understanding of streams and fluctuations was enhanced by the acquisition of nearly complete sets of high resolution plasma and magnetic data simultaneously at two or more points by IMPs 6, 7, and 8, Mariner-Venus-Mercury, HELIOS 1, and HELIOS 2. Observations demonstrate that streams can have very thin boundaries in latitude and longitude near the sun. This has necessitated a revision of earlier views of stream dynamics, for it is now clear that magnetic pressure is a major factor in the dynamics of stream in the inner solar system and that nonlinear phenomena are significant much closer to the sun than previously believed. Simultaneous IMP 6, 7, and 8 observations of Alfvenic fluctuations indicate that they are probably not simply transverse Alfven waves and suggest that Alfvenic fluctuations are better described as nonplanar, large-amplitude, general Alfven waves moving through an inhomogeneous and discontinuous medium, and coupled to a compressive mode.

  14. On the Magnetization of Cosmic Outflows: Plasma Modes and Instabilities of Unmagnetized Plasma Beams

    NASA Astrophysics Data System (ADS)

    Michno, M. J.; Schlickeiser, R.

    2010-05-01

    The dissipation of the kinetic energy of cosmic outflows in interactions with ambient collision-free plasmas and the associated generation of electromagnetic plasma turbulence is a fundamental problem of modern astrophysics. Thermalization by elastic two-body Coulomb collisions is orders of magnitudes too slow as compared to interactions with electric and magnetic fields because of the generally low density of cosmic plasmas. Alternative dissipation mechanisms have to be examined such as energy diffusion by second-order Fermi interactions of charged particles with electromagnetic turbulence, which are an intrinsic property of any sufficiently agitated magnetized plasma. We consider the microphysical details of the energy conversion in relativistic and nonrelativistic outflows by investigating the solutions of the linear plasma dispersion relation in an unmagnetized anisotropic beam plasma consisting of two overall-neutral particle beams propagating with arbitrary velocities in the same direction. The general plasma dispersion relation is derived for arbitrary propagation angle θ with respect to the beam propagation direction both in the initial laboratory frame and in the counterstream frame of reference. Solutions of the linear dispersion relation are derived for parallel (θ = π/2) and perpendicular (θ = 0) propagation angle, respectively. For parallel propagation angles, the electrostatic mode is excited and its maximum growth rate depends on the relative bulk Lorentz factor of the flows and their density ratio. For perpendicular propagation angles, the aperiodic filamentation mode is excited and its maximum growth rate depends differently on the relative bulk Lorentz factor of the flow and their density ratio. The respective maximum growth rates indicate that for nonrelativistic flow velocities the electrostatic instability (EI) is excited much faster than the filamentation instability (FI), whereas for relativistic flow velocities the FI has a larger growth

  15. Typical Profiles and Distributions of Plasma and Magnetic Field Parameters in Magnetic Clouds at 1 AU

    NASA Astrophysics Data System (ADS)

    Rodriguez, L.; Masías-Meza, J. J.; Dasso, S.; Démoulin, P.; Zhukov, A. N.; Gulisano, A. M.; Mierla, M.; Kilpua, E.; West, M.; Lacatus, D.; Paraschiv, A.; Janvier, M.

    2016-08-01

    Magnetic clouds (MCs) are a subset of interplanetary coronal mass ejections (ICMEs). They are important because of their simple internal magnetic field configuration, which resembles a magnetic flux rope, and because they represent one of the most geoeffective types of solar transients. In this study, we analyze their internal structure using a superposed epoch method on 63 events observed at L1 by the Advance Composition Explorer (ACE), between 1998 and 2006. In this way, we obtain an average profile for each plasma and magnetic field parameter at each point of the cloud. Furthermore, we take a fixed time-window upstream and downstream from the MC to also sample the regions preceding the cloud and the wake trailing it. We then perform a detailed analysis of the internal characteristics of the clouds and their surrounding solar wind environments. We find that the parameters studied are compatible with log-normal distribution functions. The plasma β and the level of fluctuations in the magnetic field vector are the best parameters to define the boundaries of MCs. We find that one third of the events shows a peak in plasma density close to the trailing edge of the flux ropes. We provide several possible explanations for this result and investigate if the density peak is of a solar origin ( e.g. erupting prominence material) or formed during the magnetic cloud travel from the Sun to 1 AU. The most plausible explanation is the compression due to a fast overtaking flow, coming from a coronal hole located to the east of the solar source region of the magnetic cloud.

  16. Use of a probing pulsed magnetic field for determining plasma parameters

    NASA Astrophysics Data System (ADS)

    Rousskikh, A. G.; Oreshkin, V. I.; Zhigalin, A. S.; Yushkov, G. Yu.

    2016-11-01

    A novel, simple, and readily usable method is proposed for measuring the electrical conductivity and temperature of a plasma. The method is based on the interaction of the test plasma with a pulsed magnetic field. The electric signals induced by the magnetic field in the circuits of two probes (miniature solenoids), one immersed in the test plasma and the other placed outside the plasma, provide data for estimating the plasma parameters. The method was verified experimentally by determining the parameters of the plasma flows generated in the cathode spots high-current pulsed vacuum arcs that were used to form cylindrical shells of bismuth Z-pinch plasma.

  17. Modeling of plasma transport and negative ion extraction in a magnetized radio-frequency plasma source

    NASA Astrophysics Data System (ADS)

    Fubiani, G.; Garrigues, L.; Hagelaar, G.; Kohen, N.; Boeuf, J. P.

    2017-01-01

    Negative ion sources for fusion are high densities plasma sources in large discharge volumes. There are many challenges in the modeling of these sources, due to numerical constraints associated with the high plasma density, to the coupling between plasma and neutral transport and chemistry, the presence of a magnetic filter, and the extraction of negative ions. In this paper we present recent results concerning these different aspects. Emphasis is put on the modeling approach and on the methods and approximations. The models are not fully predictive and not complete as would be engineering codes but they are used to identify the basic principles and to better understand the physics of the negative ion sources.

  18. Control of Internal Transport Barriers in Magnetically Confined Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Panta, Soma; Newman, David; Sanchez, Raul; Terry, Paul

    2016-10-01

    In magnetic confinement fusion devices the best performance often involves some sort of transport barriers to reduce the energy and particle flow from core to edge. Those barriers create gradients in the temperature and density profiles. If gradients in the profiles are too steep that can lead to instabilities and the system collapses. Control of these barriers is therefore an important challenge for fusion devices (burning plasmas). In this work we focus on the dynamics of internal transport barriers. Using a simple 7 field transport model, extensively used for barrier dynamics and control studies, we explore the use of RF heating to control the local gradients and therefore the growth rates and shearing rates for barrier initiation and control in self-heated fusion plasmas. Ion channel barriers can be formed in self-heated plasmas with some NBI heating but electron channel barriers are very sensitive. They can be formed in self-heated plasmas with additional auxiliary heating i.e. NBI and radio-frequency(RF). Using RF heating on both electrons and ions at proper locations, electron channel barriers along with ion channel barriers can be formed and removed demonstrating a control technique. Investigating the role of pellet injection in controlling the barriers is our next goal. Work supported by DOE Grant DE-FG02-04ER54741.

  19. Coupling of an exploding plasma to a magnetized ambient plasma measured with LIF

    NASA Astrophysics Data System (ADS)

    Bonde, Jeffrey; Vincena, Stephen; Gekelman, Walter

    2013-10-01

    The coupling of plasma jets to ambient media near young stellar objects, Herbig-Haro objects, and supernova remnants is of considerable interest to the astrophysical community. In this work, we study the interaction of a laboratory scale jet formed by a carbon laser-produced plasma (LPP) with the ions of a magnetized argon background plasma (njet /nAr < 30 ,vjet/cs = 20 ,vjet/vA <=1) using laser-induced fluorescence (LIF). The excitation light was provided by a planar beam of a pulsed dye laser which, by tuning to the Doppler-broadened 611.5 nm absorption line, sampled the distribution function of metastable Ar-II separating the background from the components of the jet. A fast shutter (>= 3 ns) CCD camera captured the 461 nm fluorescence with 40 ns time and .6 mm2 spatial resolutions. The distribution functions obtained from the LIF diagnostic reveal significant density enhancement and a subsonic parallel drift localized at the LPP-ambient interface. Within the jet region, the background ion signal indicates the formation of a density void and suggests a lateral snow-plow effect. To our knowledge, this is the first LIF measurement of a supersonic jet coupling to an ambient plasma. Supplemental Langmuir probe measurements characterize the jet's dimensions and dependence on magnetic field strength and background ion mass up to 6 meters from the LPP source. This experiment was conducted in the Large Plasma Device at the Basic Plasma Science Facility and funded by grants from the US Department of Energy and the National Science Foundation.

  20. Energy transfer and dual cascade in kinetic magnetized plasma turbulence.

    PubMed

    Plunk, G G; Tatsuno, T

    2011-04-22

    The question of how nonlinear interactions redistribute the energy of fluctuations across available degrees of freedom is of fundamental importance in the study of turbulence and transport in magnetized weakly collisional plasmas, ranging from space settings to fusion devices. In this Letter, we present a theory for the dual cascade found in such plasmas, which predicts a range of new behavior that distinguishes this cascade from that of neutral fluid turbulence. These phenomena are explained in terms of the constrained nature of spectral transfer in nonlinear gyrokinetics. Accompanying this theory are the first observations of these phenomena, obtained via direct numerical simulations using the gyrokinetic code AstroGK. The basic mechanisms that are found provide a framework for understanding the turbulent energy transfer that couples scales both locally and nonlocally.

  1. Auroral electrostatic solitons and supersolitons in a magnetized nonthermal plasma

    SciTech Connect

    Rufai, O. R.

    2015-05-15

    Exploiting the spacecraft measurements in the auroral region, finite amplitude nonlinear low frequency electrostatic solitons and supersolitons in a magnetized plasma consisting of cold ions fluid, Boltzmann protons, and nonthermal hot electrons are studied by applying a pseudo-potential technique. The localized solution of the nonlinear structures is obtained through the charge neutrality condition. Further numerical investigation shows the existence of supersoliton solutions at supersonic Mach numbers regime. The amplitude of ion-acoustic structures decreased with an increase in nonthermal electrons and ion density ratio. For the plasma parameters relevant to the auroral zone of the Earth's magnetosphere, the electric field amplitude of supersolitons is found to be about 9 mV/m, which is in agreement with satellite observations.

  2. Asymptotic-preserving Lagrangian approach for modeling anisotropic transport in magnetized plasmas for arbitrary magnetic fields

    NASA Astrophysics Data System (ADS)

    Chacon, Luis; Del-Castillo-Negrete, Diego; Hauck, Cory

    2012-10-01

    Modeling electron transport in magnetized plasmas is extremely challenging due to the extreme anisotropy between parallel (to the magnetic field) and perpendicular directions (χ/χ˜10^10 in fusion plasmas). Recently, a Lagrangian Green's function approach, developed for the purely parallel transport case,footnotetextD. del-Castillo-Negrete, L. Chac'on, PRL, 106, 195004 (2011)^,footnotetextD. del-Castillo-Negrete, L. Chac'on, Phys. Plasmas, 19, 056112 (2012) has been extended to the anisotropic transport case in the tokamak-ordering limit with constant density.footnotetextL. Chac'on, D. del-Castillo-Negrete, C. Hauck, JCP, submitted (2012) An operator-split algorithm is proposed that allows one to treat Eulerian and Lagrangian components separately. The approach is shown to feature bounded numerical errors for arbitrary χ/χ ratios, which renders it asymptotic-preserving. In this poster, we will present the generalization of the Lagrangian approach to arbitrary magnetic fields. We will demonstrate the potential of the approach with various challenging configurations, including the case of transport across a magnetic island in cylindrical geometry.

  3. Magnetic Reconnection: A Fundamental Process in Space Plasmas

    NASA Technical Reports Server (NTRS)

    Hesse, Michael

    2010-01-01

    For many years, collisionless magnetic reconnect ion has been recognized as a fundamental process, which facilitates plasma transport and energy release in systems ranging from the astrophysical plasmas to magnetospheres and even laboratory plasma. Beginning with work addressing solar dynamics, it has been understood that reconnection is essential to explain solar eruptions, the interaction of the solar wind with the magnetosphere, and the dynamics of the magnetosphere. Accordingly, the process of magnetic reconnection has been and remains a prime target for space-based and laboratory studies, as well as for theoretical research. Much progress has been made throughout the years, beginning with indirect verifications by studies of processes enabled by reconnection, such as Coronal Mass Ejections, Flux Transfer Events, and Plasmoids. Theoretical advances have accompanied these observations, moving knowledge beyond the Sweet-Parker theory to the recognition that other, collisionless, effects are available and likely to support much faster reconnect ion rates. At the present time we are therefore near a break-through in our understanding of how collisionless reconnect ion works. Theory and modeling have advanced to the point that two competing theories are considered leading candidates for explaining the microphysics of this process. Both theories predict very small spatial and temporal scales. which are. to date, inaccessible to space-based or laboratory measurements. The need to understand magnetic reconnect ion has led NASA to begin the implementation of a tailored mission, Magnetospheric MultiScale (MMS), a four spacecraft cluster equipped to resolve all relevant spatial and temporal scales. In this presentation, we present an overview of current knowledge as well as an outlook towards measurements provided by MMS.

  4. Plasma Heating During Magnetic Reconnection: Implications for Turbulent Dissipation

    NASA Astrophysics Data System (ADS)

    Shay, M. A.; Parashar, T.; Matthaeus, W. H.; Haggerty, C. C.

    2015-12-01

    Current sheets and associated intermittency are known to be prevalent in many turbulent plasmas and have been shown to be correlated with heating in observations of solar wind turbulence [1] and dissipation in kinetic particle-in-cell simulations [5]. Most intriguing, recent PIC simulations have found that the relative ion to electron heating ratio is strongly dependent on the turbulence amplitude [3]. An important question is whether magnetic reconnection is an important mechanism responsible for this heating. Studies focused on laminar reconnection have made significant progress recently on the magnitude and physics responsible for heating during magnetic reconnection [2,4]. The ambient Alfven speed of plasma flowing into the reconnection region plays a critical role, with heating initially taking the form of counterstreaming beams generated by non-local acceleration mechanism. However, there are significant uncertainties with how to link this basic reconnection heating with generic heating in a turbulent plasma. In this presentation, our current understanding of heating due to reconnection will be reviewed, and the factors determining the applicability of this heating to turbulent dissipation and heating will be discussed. These ideas will be explored through the comparison of kinetic PIC simulations of turbulence with reconnection heating models. Key aspects that will be examined are the effect of differing turbulent conditions on the magnitude and anisotropy of the heating, as well as the ion to electron heating ratio. [1] Osman et al., ApJ Letters, 727, L11, 2011. [2] Phan, et al., GRL, 40, 50917, 2013. [3] Wu et al., ApJ Letters, 763, L30, 2013. [4] Shay et al., Phys. Plasmas, 21, 122902, 2014. [5] Wan et al., PRL, 114, 175002, 2015.

  5. Pulsed expansion of plasma in a magnetic thruster

    SciTech Connect

    Iinoya, F.

    1993-01-01

    The inertial confinement fusion (ICF) pulse rocket is capable of extremely high specific impulses and high thrust-to-weight ratios by virtue of intermittent nuclear fusion energy production isolated from the vehicle structure. The thruster of the rocket, which converts an initially isotropically expanding ICF debris plasma into a directed pulse jet exhaust, is to be fabricated out of magnetic fields created by current coils attached to the vehicle. Thrust is obtained through the property that good conductors exclude magnetic fields. Because of the highly dynamic behavior of the flow, which is bounded by an interface whose motion is unknown a priori, the first problem investigated is that of the bulk flow. Numerical simulations of the bulk flow process were conducted under the thin-shell and the classical hydrodynamic approximations. In the former approach, all of the plasma is assumed to be collected into an azimuthally symmetric perfectly conducting thin shell at the interface due to interfacial pressure application. Under idealized conditions, promising propulsive efficiencies could be obtained for a range of field-to-plasma energy ratios and thruster geometries. In the latter approach, the plasma is approximated as an unmagnetized perfectly conducting fluid obeying the laws of classical hydrodynamics. The hydrodynamic codes (both 1-D and 2-D) employed an advanced Classical Particle-In-Cell (PIC) scheme, and were successful at capturing interface motions self-consistently. The shock arising from the interface deceleration was also captured correctly. One-dimensional planar-geometry simulations gave results which matched well with analytical calculations for such processes as free expansion into a vacuum and shock-tube problems. The formation of a shell-like structure originating from the interfacial regions was observed in simulations of large expansion ratio flows carried out in two dimensions, although these shells did not necessarily stay at the interface.

  6. Magnetic Flux Concentrations in Stratified Turbulent Plasma Due to Negative Effective Magnetic Pressure Instability

    NASA Astrophysics Data System (ADS)

    Jabbari, S.; Brandenburg, A.

    2014-12-01

    Recent studies have suggested a new mechanism that can be used to explain the formation of magnetic spots or bipolar regions in highly stratified turbulent plasmas. According to this model, a large-scale magnetic field suppresses the turbulent pressure, which leads to a negative contribution of turbulence to the effective magnetic pressure. Direct numerical simulations (DNS) have confirmed that the negative contribution is large enough so that the effective magnetic pressure becomes negative and leads to a large-scale instability, which we refer to as negative effective magnetic pressure Instability (NEMPI). NEMPI was used to explain the formation of active regions and sunspots on the solar surface. One step toward improving this model was to combine dynamo in- stability with NEMPI. The dynamo is known to be responsible for the solar large-scale magnetic field and to play a role in solar activity. In this context, we studied stratified turbulent plasmas in spherical geometry, where the background field was generated by alpha squared dynamo. For NEMPI to be excited, the initial magnetic field should be in a proper range, so we used quenching function for alpha. Using the Pencil Code and mean field simulations (MFS), we showed that in the presence of dynamo-generated magnetic fields, we deal with a coupled system, where both instabilities, dynamo and NEMPI, work together and lead to the formation of magnetic structures (Jabbari et al. 2013). We also studied a similar system in plane geometry in the presence of rotation and confirmed that for slow rotation NEMPI works, but as the Coriolis number increases, the rotation suppresses NEMPI. By increasing the Coriolis number even further, the combination of fast rotation and high stratification excites a dynamo, which leads again to a coupled system of dynamo and NEMPI (Jabbari et al. 2014). Another important finding concerning NEMPI is the case where the instability is excited by a vertical magnetic field (Brandenburg et

  7. Solitary perturbations in the steep boundary of magnetized toroidal plasma

    NASA Astrophysics Data System (ADS)

    Lee, J. E.; Yun, G. S.; Lee, W.; Kim, M. H.; Choi, M.; Lee, J.; Kim, M.; Park, H. K.; Bak, J. G.; Ko, W. H.; Park, Y. S.

    2017-03-01

    Solitary perturbations (SPs) localized both poloidally and radially are detected within ~100 μs before the partial collapse of the high pressure gradient boundary region (called pedestal) of magnetized toroidal plasma in the KSTAR tokamak device. The SP develops with a low toroidal mode number (typically unity) in the pedestal ingrained with quasi-stable edge-localized mode (QSM) which commonly appears during the inter-collapse period. The SPs have smaller mode pitch and different (often opposite) rotation velocity compared to the QSMs. Similar solitary perturbations are also frequently observed before the onset of complete pedestal collapse, suggesting a strong connection between the SP generation and the pedestal collapse.

  8. Wave propagation in a moving cold magnetized plasma

    NASA Astrophysics Data System (ADS)

    Hebenstreit, H.

    1980-03-01

    Polarization relations and dispersion equations are derived for media that are electrically anisotropic in the comoving frame. Three-dimensional calculations for media at rest recover the known dispersion equations, i.e., Astrom's dispersion equation for magnetized cold plasmas and Fresnel's wave normal equation for uniaxial crystals. An analogous four-dimensional calculation yields the generalization to moving media. The dispersion equations so obtained for moving gyrotropic media are then discussed qualitatively for various special media and special directions of wave propagation. Finally, the polarization relations are specialized to media gyrotropic in the comoving frame.

  9. Effects of magnetic islands on bootstrap current in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Dong, G.; Lin, Z.

    2017-03-01

    The effects of magnetic islands on electron bootstrap current in toroidal plasmas are studied using gyrokinetic simulations. The magnetic islands cause little changes of the bootstrap current level in the banana regime because of trapped electron effects. In the plateau regime, the bootstrap current is completely suppressed at the island centers due to the destruction of trapped electron orbits by collisions and the flattening of pressure profiles by the islands. In the collisional regime, small but finite bootstrap current can exist inside the islands because of the pressure gradients created by large collisional transport across the islands. Finally, simulation results show that the bootstrap current level increases near the island separatrix due to steeper local density gradients.

  10. Antiproton powered propulsion with magnetically confined plasma engines

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1989-01-01

    The reaction of the matter-antimatter annihilation, with its specific energy being over 250 times the specific energy released in nuclear fusion, is considered as an energy source for spacecraft propulsion. A concept of a magnetically confined pulsed plasma engine is described. In this concept, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas; the resulting charge annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. Numerical simulations were developed to calculate the annihilation rate of antiprotons in hydrogen and to follow the resulting ion, muon, and electron/positron number density evolutions.

  11. Antiproton powered propulsion with magnetically confined plasma engines

    SciTech Connect

    Lapointe, M.R.

    1989-01-01

    The reaction of the matter-antimatter annihilation, with its specific energy being over 250 times the specific energy released in nuclear fusion, is considered as an energy source for spacecraft propulsion. A concept of a magnetically confined pulsed plasma engine is described. In this concept, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas; the resulting charge annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. Numerical simulations were developed to calculate the annihilation rate of antiprotons in hydrogen and to follow the resulting ion, muon, and electron/positron number density evolutions. 22 refs.

  12. Kinetic theory of weak turbulence in magnetized plasmas: Perpendicular propagation

    SciTech Connect

    Yoon, Peter H.

    2015-08-15

    The present paper formulates a weak turbulence theory in which electromagnetic perturbations are assumed to propagate in directions perpendicular to the ambient magnetic field. By assuming that all wave vectors lie in one direction transverse to the ambient magnetic field, the linear solution and second-order nonlinear solutions to the equation for the perturbed distribution function are obtained. Nonlinear perturbed current from the second-order nonlinearity is derived in general form, but the limiting situation of cold plasma temperature is taken in order to derive an explicit nonlinear wave kinetic equation that describes three-wave decay/coalescence interactions among X and Z modes. A potential application of the present formalism is also discussed.

  13. 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.

  14. Magnetic flux and heat losses by diffusive, advective, and Nernst effects in magnetized liner inertial fusion-like plasma

    SciTech Connect

    Velikovich, A. L.; Giuliani, J. L.; Zalesak, S. T.

    2015-04-15

    The magnetized liner inertial fusion (MagLIF) approach to inertial confinement fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010); Cuneo et al., IEEE Trans. Plasma Sci. 40, 3222 (2012)] involves subsonic/isobaric compression and heating of a deuterium-tritium plasma with frozen-in magnetic flux by a heavy cylindrical liner. The losses of heat and magnetic flux from the plasma to the liner are thereby determined by plasma advection and gradient-driven transport processes, such as thermal conductivity, magnetic field diffusion, and thermomagnetic effects. Theoretical analysis based on obtaining exact self-similar solutions of the classical collisional Braginskii's plasma transport equations in one dimension demonstrates that the heat loss from the hot compressed magnetized plasma to the cold liner is dominated by transverse heat conduction and advection, and the corresponding loss of magnetic flux is dominated by advection and the Nernst effect. For a large electron Hall parameter (ω{sub e}τ{sub e}≫1), the effective diffusion coefficients determining the losses of heat and magnetic flux to the liner wall are both shown to decrease with ω{sub e}τ{sub e} as does the Bohm diffusion coefficient cT/(16eB), which is commonly associated with low collisionality and two-dimensional transport. We demonstrate how this family of exact solutions can be used for verification of codes that model the MagLIF plasma dynamics.

  15. Magnetic flux and heat losses by diffusive, advective, and Nernst effects in magnetized liner inertial fusion-like plasma

    NASA Astrophysics Data System (ADS)

    Velikovich, A. L.; Giuliani, J. L.; Zalesak, S. T.

    2015-04-01

    The magnetized liner inertial fusion (MagLIF) approach to inertial confinement fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010); Cuneo et al., IEEE Trans. Plasma Sci. 40, 3222 (2012)] involves subsonic/isobaric compression and heating of a deuterium-tritium plasma with frozen-in magnetic flux by a heavy cylindrical liner. The losses of heat and magnetic flux from the plasma to the liner are thereby determined by plasma advection and gradient-driven transport processes, such as thermal conductivity, magnetic field diffusion, and thermomagnetic effects. Theoretical analysis based on obtaining exact self-similar solutions of the classical collisional Braginskii's plasma transport equations in one dimension demonstrates that the heat loss from the hot compressed magnetized plasma to the cold liner is dominated by transverse heat conduction and advection, and the corresponding loss of magnetic flux is dominated by advection and the Nernst effect. For a large electron Hall parameter ( ωeτe≫1 ), the effective diffusion coefficients determining the losses of heat and magnetic flux to the liner wall are both shown to decrease with ωeτe as does the Bohm diffusion coefficient c T /(16 e B ) , which is commonly associated with low collisionality and two-dimensional transport. We demonstrate how this family of exact solutions can be used for verification of codes that model the MagLIF plasma dynamics.

  16. Rogue Mode Shileding in NSLS-II Multipole Vacuum Chambers

    SciTech Connect

    Ferreira, M.; Blednykh, A.; Bacha, B.; Borrelli, A.; Hseuh, H.-C.; Kosciuk, B.; Krinsky, S.; Singh, O.; Vetter, K.

    2011-03-28

    Modes with transverse electric field (TE-modes) in the NSLS-II multipole vacuum chamber can be generated at frequencies above 450MHz due to its geometric dimensions. Since the NSLS-II BPM system monitors signals within 10 MHz band at RF frequency of 500 MHz, frequencies of higher-order modes (HOM) can be generated within the transmission band of the band pass filter. In order to avoid systematic errors in the NSLS-II BPM system, we introduced frequency shift of HOMs by using RF metal shielding located in the antechamber slot. We demonstrated numerical modeling and experimental studies of the spurious TE modes in the NSLS-II vacuum chambers with antechamber slot. Calculated frequencies of TE-modes in considered chambers with and without RF shielding were verified experimentally. Flexible BeCu RF shielding inside each chamber at proper location shifts frequencies of H{sub 10p}-modes above {approx}900MHz, except chambers S6 odd and even. These chambers need special attention because of synchrotron radiation from downstream magnets. S6 odd multipole vacuum chamber needs to be measured and the RF shielding length has to be optimized. RF shielding looks adequate for baseline design. Fifty percent of open space provides adequate pumping speed.

  17. Magnetic field generation, Weibel-mediated collisionless shocks, and magnetic reconnection in colliding laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fox, W.; Bhattacharjee, A.; Fiksel, G.

    2016-10-01

    Colliding plasmas are ubiquitous in astrophysical environments and allow conversion of kinetic energy into heat and, most importantly, the acceleration of particles to extremely high energies to form the cosmic ray spectrum. In collisionless astrophysical plasmas, kinetic plasma processes govern the interaction and particle acceleration processes, including shock formation, self-generation of magnetic fields by kinetic plasma instabilities, and magnetic field compression and reconnection. How each of these contribute to the observed spectra of cosmic rays is not fully understood, in particular both shock acceleration processes and magnetic reconnection have been proposed. We will review recent results of laboratory astrophysics experiments conducted at high-power, inertial-fusion-class laser facilities, which have uncovered significant results relevant to these processes. Recent experiments have now observed the long-sought Weibel instability between two interpenetrating high temperature plasma plumes, which has been proposed to generate the magnetic field necessary for shock formation in unmagnetized regimes. Secondly, magnetic reconnection has been studied in systems of colliding plasmas using either self-generated magnetic fields or externally applied magnetic fields, and show extremely fast reconnection rates, indicating fast destruction of magnetic energy and further possibilities to accelerate particles. Finally, we highlight kinetic plasma simulations, which have proven to be essential tools in the design and interpretation of these experiments.

  18. Magnetized Plasma-filled Waveguide: A New High-Gradient Accelerating Structure

    SciTech Connect

    Avitzour, Yoav; Shvets, Gennady

    2009-01-22

    Electromagnetic waves confined between the metal plates of a plasma-filled waveguide are investigated. It is demonstrated that when the plasma is magnetized along the metallic plates, there exists a luminous accelerating wave propagating with a very slow group velocity. It is shown that the magnetized plasma 'isolates' the metal wall from the transverse electric field, thereby reducing potential breakdown problems. Applications of the metallic plasma-filled waveguide to particle accelerations and microwave pulse manipulation are described.

  19. Venus' nighttime horizontal plasma flow, 'magnetic congestion', and ionospheric hole production

    NASA Astrophysics Data System (ADS)

    Grebowsky, J. M.; Mayr, H. G.; Curtis, S. A.; Taylor, H. A.

    1983-04-01

    A simple rectilinear, two-dimensional MHD model is used to investigate the effects of field-aligned plasma loss and cooling on a dense plasma convecting across a weak magnetic field, in order to illumine the Venus nighttime phenomena of horizontal plasma flow, magnetic congestion and ionospheric hole production. By parameterizing field-aligned variations and explicitly solving for cross magnetic field variations, it is shown that the abrupt horizontal enhancements of the vertical magnetic field, as well as sudden decreases of the plasma density to very low values (which are characteristic of ionospheric holes), can be produced in the presence of field-aligned losses.

  20. Magnetic Probe to Study Plasma Jets for Magneto-Inertial Fusion

    SciTech Connect

    Martens, Daniel; Hsu, Scott C.

    2012-08-16

    A probe has been constructed to measure the magnetic field of a plasma jet generated by a pulsed plasma rail-gun. The probe consists of two sets of three orthogonally-oriented commercial chip inductors to measure the three-dimensional magnetic field vector at two separate positions in order to give information about the magnetic field evolution within the jet. The strength and evolution of the magnetic field is one of many factors important in evaluating the use of supersonic plasma jets for forming imploding spherical plasma liners as a standoff driver for magneto-inertial fusion.

  1. Modeling and Optimizing RF Multipole Ion Traps

    NASA Astrophysics Data System (ADS)

    Fanghaenel, Sven; Asvany, Oskar; Schlemmer, Stephan

    2016-06-01

    Radio frequency (rf) ion traps are very well suited for spectroscopy experiments thanks to the long time storage of the species of interest in a well defined volume. The electrical potential of the ion trap is determined by the geometry of its electrodes and the applied voltages. In order to understand the behavior of trapped ions in realistic multipole traps it is necessary to characterize these trapping potentials. Commercial programs like SIMION or COMSOL, employing the finite difference and/or finite element method, are often used to model the electrical fields of the trap in order to design traps for various purposes, e.g. introducing light from a laser into the trap volume. For a controlled trapping of ions, e.g. for low temperature trapping, the time dependent electrical fields need to be known to high accuracy especially at the minimum of the effective (mechanical) potential. The commercial programs are not optimized for these applications and suffer from a number of limitations. Therefore, in our approach the boundary element method (BEM) has been employed in home-built programs to generate numerical solutions of real trap geometries, e.g. from CAD drawings. In addition the resulting fields are described by appropriate multipole expansions. As a consequence, the quality of a trap can be characterized by a small set of multipole parameters which are used to optimize the trap design. In this presentation a few example calculations will be discussed. In particular the accuracy of the method and the benefits of describing the trapping potentials via multipole expansions will be illustrated. As one important application heating effects of cold ions arising from non-ideal multipole fields can now be understood as a consequence of imperfect field configurations.

  2. Vertically magnetic-controlled THz modulator based on 2-D magnetized plasma photonic crystal

    NASA Astrophysics Data System (ADS)

    Zhou, Wen; Chen, He-ming; Ji, Ke; Zhuang, Yuyang

    2017-02-01

    A novel magnetized plasma modulator for THz range is proposed. The structure is based on 2-D photonic crystal (PC) constructed by triangular lattice of Si rods in air with line defects and an InSb rod as a point defect. Based on the magneto-optic effect, the resonant frequency can be tuned by the external magnetic field and the radius of point defect. The transfer and disappearance of the PC-based mode can be realized by utilizing a waveguide and a plasma cavity. The simulation results show that PC-based mode disappearance modulator has the potential for THz wireless broadband communication system with a good performance of high contrast ratio (<33.61 dB), low insertion loss (<0.36 dB) and high modulation rate (∼4 GHz).

  3. Characteristics of the Plasma Distribution in Mercury's Equatorial Magnetosphere Derived from MESSENGER Magnetic Field and Plasma Observations

    NASA Astrophysics Data System (ADS)

    Korth, H.; Anderson, B. J.; Johnson, C. L.; Winslow, R. M.; Raines, J. M.; Slavin, J. A.; Purucker, M. E.; Zurbuchen, T.; Solomon, S. C.; McNutt, R. L.

    2012-12-01

    Localized reductions in the magnetic field associated with plasma pressure in Mercury's plasma sheet have been routinely observed by the Magnetometer on the MErcury Surface, Space ENvironment, Geochemistry, and Ranging (MESSENGER) spacecraft. We present a statistical analysis of near-equatorial magnetic depressions to derive the structure of Mercury's plasma sheet pressure. Because the plasma pressure in the magnetosphere correlates with solar wind density, the pressures were normalized to a Mercury heliocentric distance of 0.39 AU. A model magnetic field was used to map observations obtained on the ascending and descending orbit nodes to the magnetic equator, and the mapped equatorial distribution revealed the presence of plasma in a toroidal section extending on the nightside from dusk to dawn. Mapping the data to invariant magnetic latitude shows that the pressure is symmetric about the magnetic equator. The average pressure normalized for heliocentric distance is 1.45 nPa and exhibits a weak, 0.05 nPa/h, dusk-to-dawn gradient with local time. The plasma sheet pressure can vary between successive orbits by an order of magnitude. Unlike the predictions of some global simulations of Mercury's magnetosphere but consistent with observations by MESSENGER's Fast Imaging Plasma Spectrometer, the plasma enhancements do not form a closed distribution around the planet. This difference may arise from the idealized solar wind and interplanetary magnetic field conditions used in the simulations, conditions that maximize the size and stability of the magnetosphere and thus promote the formation of drift paths that close around the planet. For typical plasma sheet energies, 5 keV, the first adiabatic invariant for protons fails to be conserved even within 500 km altitude at midnight, implying that stochastic processes must be considered in plasma sheet transport.

  4. Superconducting applications in propulsion systems. Magnetic insulation for plasma propulsion devices

    NASA Technical Reports Server (NTRS)

    Gonzalez, Dora E.; Karr, Gerald R.

    1990-01-01

    The purpose of this paper is to review the status of knowledge of the basic concepts needed to establish design parameters for effective magnetic insulation. The objective is to estimate the effectiveness of the magnetic field in insulating the plasma, to calculate the magnitude of the magnetic field necessary to reduce the heat transfer to the walls sufficiently enough to demonstrate the potential of magnetically driven plasma rockets.

  5. Diamagnetic boundary layers - A kinetic theory. [for collisionless magnetized plasmas

    NASA Technical Reports Server (NTRS)

    Lemaire, J.; Burlaga, L. F.

    1976-01-01

    A kinetic theory is presented for boundary layers associated with MHD tangential 'discontinuities' in a collisionless magnetized plasma, such as those observed in the solar wind. The theory consists of finding self-consistent solutions of Vlasov's equation and Maxwell's equation for stationary one-dimensional boundary layers separating two Maxwellian plasma states. Layers in which the current is carried by electrons are found to have a thickness of the order of a few electron gyroradii, but the drift speed of the current-carrying electrons is found to exceed the Alfven speed, and accordingly such layers are not stable. Several types of layers in which the current is carried by protons are discussed; in particular, cases are considered in which the magnetic-field intensity, direction, or both, changed across the layer. In every case, the thickness was of the order of a few proton gyroradii, and the field changed smoothly, although the characteristics depended somewhat on the boundary conditions. The drift speed was always less than the Alfven speed, consistent with stability of such structures. These results are consistent with observations of boundary layers in the solar wind near 1 AU.

  6. Plasma dynamics and heating/acceleration during driven magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Cheng, C. Z.; Inoue, Shizuo; Ono, Yasushi; Horiuchi, Ritoku

    2015-11-01

    Highlights of the plasma dynamics and energization during driven anti-parallel magnetic reconnection are presented. The MHD condition breaks down in the entire reconnection layer (the reconnection current layer, the separatrix region and the whole downstream), and the plasma dynamics is significantly different from the results of the Hall-MHD model. In particular, we explain (1) how electron and ion dynamics decouple and how the charge separation and electrostatic electric field are produced in the magnetic field reversal region (reconnection current layer and outflow exhaust) and around the separatrix regions, (2) how electrons and ions gain energy in the reconnection current layer, (3) why the electron outflow velocity in the reconnection exhaust reaches super-Alfvenic speed and the ion outflow velocity reaches Alfvenic speed and how the parallel electric field is produced, (4) how electrons are accelerated by the parallel electric field around the separatrix region, and (5) how ions gain energy when they move across the separatrix region into the downstream. Finally we show that electrons and ions gain energy mainly from the inductive reconnection driven electric field and less from the electrostatic electric field.

  7. Generation of electromagnetic emission during the injection of dense supersonic plasma flows into arched magnetic field

    NASA Astrophysics Data System (ADS)

    Viktorov, Mikhail; Golubev, Sergey; Mansfeld, Dmitry; Vodopyanov, Alexander

    2016-04-01

    Interaction of dense supersonic plasma flows with an inhomogeneous arched magnetic field is one of the key problems in near-Earth and space plasma physics. It can influence on the energetic electron population formation in magnetosphere of the Earth, movement of plasma flows in magnetospheres of planets, energy release during magnetic reconnection, generation of electromagnetic radiation and particle precipitation during solar flares eruption. Laboratory study of this interaction is of big interest to determine the physical mechanisms of processes in space plasmas and their detailed investigation under reproducible conditions. In this work a new experimental approach is suggested to study interaction of supersonic (ion Mach number up to 2.7) dense (up to 1015 cm-3) plasma flows with inhomogeneous magnetic field (an arched magnetic trap with a field strength up to 3.3 T) which opens wide opportunities to model space plasma processes in laboratory conditions. Fully ionized plasma flows with density from 1013 cm-3 to 1015 cm-3 are created by plasma generator on the basis of pulsed vacuum arc discharge. Then plasma is injected in an arched open magnetic trap along or across magnetic field lines. The filling of the arched magnetic trap with dense plasma and further magnetic field lines break by dense plasma flow were experimentally demonstrated. The process of plasma deceleration during the injection of plasma flow across the magnetic field lines was experimentally demonstrated. Pulsed plasma microwave emission at the electron cyclotron frequency range was observed. It was shown that frequency spectrum of plasma emission is determined by position of deceleration region in the magnetic field of the magnetic arc, and is affected by plasma density. Frequency spectrum shifts to higher frequencies with increasing of arc current (plasma density) because the deceleration region of plasma flow moves into higher magnetic field. The observed emission can be related to the

  8. Plasma, magnetic, and electromagnetic measurements at nonmagnetic bodies

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Luhmann, J. G.

    1993-01-01

    The need to explore the magnetospheres of the Earth and the giant planets is widely recognized and is an integral part of our planetary exploration program. The equal need to explore the plasma, magnetic, and electromagnetic environments of the nonmagnetic bodies is not so widely appreciated. The previous, albeit incomplete, magnetic and electric field measurements at Venus, Mars, and comets have proven critical to our understanding of their atmospheres and ionospheres in areas ranging from planetary lightning to solar wind scavenging and accretion. In the cases of Venus and Mars, the ionospheres can provide communication paths over the horizon for low-altitude probes and landers, but we know little about their lower boundaries. The expected varying magnetic fields below these planetary ionospheres penetrates the planetary crusts and can be used to sound the electrical conductivity and the thermal profiles of the interiors. However, we have no knowledge of the levels of such fields, let alone their morphology. Finally, we note that the absence of an atmosphere and an ionosphere does not make an object any less interesting for the purposes of electromagnetic exploration. Even weak remanent magnetism such as that found on the Moon during the Apollo program provides insight into the present and past states of planetary interiors. We have very intriguing data from our space probes during times of both close and distant passages of asteroids that suggest they may have coherent magnetization. If true, this observation will put important constraints on how the asteroids formed and have evolved. Our planetary exploration program must exploit its full range of exploration tools if it is to characterize the bodies of the solar system thoroughly. We should especially take advantage of those techniques that are proven and require low mass, low power, and low telemetry rates to undertake.

  9. Structure of the magnetized sheath of a dusty plasma

    SciTech Connect

    Mehdipour, H.; Denysenko, I.; Ostrikov, K.

    2010-12-15

    A three-component fluid model for a dusty plasma-sheath in an oblique magnetic field is presented. The study is carried out for the conditions when the thermophoretic force associated with the electron temperature gradient is one of the most important forces affecting dust grains in the sheath. It is shown that the sheath properties (the sheath size, the electron, ion and dust particle densities and velocities, the electric field potential, and the forces affecting the dust particles) are functions of the neutral gas pressure and ion temperature, the dust size, the dust material density, and the electron temperature gradient. Effects of plasma-dust collisions on the sheath structure are studied. It is shown that an increase in the forces pushing dust particles to the wall is accompanied by a decrease in the sheath width. The results of this work are particularly relevant to low-temperature plasma-enabled technologies, where effective control of nano- and microsized particles near solid or liquid surfaces is required.

  10. On the magnetized disruption of inertially-confined plasma flows

    NASA Astrophysics Data System (ADS)

    Manuel, Mario; Kuranz, Carolyn; Rasmus, Alexander; Klein, Sallee; MacDonald, Michael; Trantham, Matt; Fein, Jeff; Belancourt, Patrick; Young, Rachel; Keiter, Paul; Drake, R. Paul; Pollock, Brad; Park, Jaebum; Hazi, Andrew; Williams, Jackson; Chen, Hui

    2016-10-01

    The creation and disruption of inertially-collimated plasma flows is investigated through experiment, simulation, and analytical modeling. Laser-generated plasma-jets are shown to be disrupted by an applied 5T B-field along the jet axis. An analytical model of the system describes the disruption mechanism through the competing effects of B-field advection and diffusion. These results indicate that for Rem 10-100, the ratio of inertial to magnetic pressures plays an important role in determining whether a jet is formed, but at high enough Rem , axial B-field amplification prevents inertial collimation altogether. This work is funded by the U.S. DOE, through the NNSA-DS and SC-OFES Joint Program in HED Laboratory Plasmas, Grant Number DE-NA0001840 and in collaboration with LLNL under contract DE-AC52-07NA27344. Support for this work was provided by NASA, under contract NAS8-03060, through Einstein Postdoctoral Fellowship Grant Number PF3-140111. Software used in this work was developed in part by the DOE NNSA ASC- and DOE Office of Science ASCR-supported Flash Center.

  11. Helical modulation of the electrostatic plasma potential due to edge magnetic islands induced by resonant magnetic perturbation fields at TEXTOR

    SciTech Connect

    Ciaccio, G. Spizzo, G.; Schmitz, O. Frerichs, H.; Abdullaev, S. S.; Evans, T. E.; White, R. B.

    2015-10-15

    The electrostatic response of the edge plasma to a magnetic island induced by resonant magnetic perturbations to the plasma edge of the circular limiter tokamak TEXTOR is analyzed. Measurements of plasma potential are interpreted by simulations with the Hamiltonian guiding center code ORBIT. We find a strong correlation between the magnetic field topology and the poloidal modulation of the measured plasma potential. The ion and electron drifts yield a predominantly electron driven radial diffusion when approaching the island X-point while ion diffusivities are generally an order of magnitude smaller. This causes a strong radial electric field structure pointing outward from the island O-point. The good agreement found between measured and modeled plasma potential connected to the enhanced radial particle diffusivities supports that a magnetic island in the edge of a tokamak plasma can act as convective cell. We show in detail that the particular, non-ambipolar drifts of electrons and ions in a 3D magnetic topology account for these effects. An analytical model for the plasma potential is implemented in the code ORBIT, and analyses of ion and electron radial diffusion show that both ion- and electron-dominated transport regimes can exist, which are known as ion and electron root solutions in stellarators. This finding and comparison with reversed field pinch studies and stellarator literature suggest that the role of magnetic islands as convective cells and hence as major radial particle transport drivers could be a generic mechanism in 3D plasma boundary layers.

  12. Cyclotron maser and plasma wave growth in magnetic loops

    NASA Technical Reports Server (NTRS)

    Hamilton, Russell J.; Petrosian, Vahe

    1990-01-01

    Cyclotron maser and plasma wave growth which results from electrons accelerated in magnetic loops are studied. The evolution of the accelerated electron distribution is determined by solving the kinetic equation including Coulomb collisions and magnetic convergence. It is found that for modest values of the column depth of the loop the growth rates of instabilities are significantly reduced and that the reduction is much larger for the cyclotron modes than for the plasma wave modes. The large decrease in the growth rate with column depth suggests that solar coronal densities must be much lower than commonly accepted in order for the cyclotron maser to operate. The density depletion has to be similar to that which occurs during auroral kilometric radiation events in the magnetosphere. The resulting distributions are much more complicated than the idealized distributions used in many theoretical studies, but the fastest growing mode can still simply be determined by the ratio of electron plasma to gyrofrequency, U=omega(sub p)/Omega(sub e). However, the dominant modes are different than for the idealized situations with growth of the z-mode largest for U approximately less than 0.5, and second harmonic x-mode (s=2) or fundamental o-mode (s=1) the dominant modes for 0.5 approximately less than U approximately less than 1. The electron distributions typically contain more than one inverted feature which could give rise to wave growth. It is shown that this can result in simultaneous amplification of more than one mode with each mode driven by a different feature and can be observed, for example, by differences in the rise times of the right and left circularly polarized components of the associated spike bursts.

  13. Transient growth of a Vlasov plasma in a weakly inhomogeneous magnetic field

    NASA Astrophysics Data System (ADS)

    Ratushnaya, Valeria; Samtaney, Ravi

    2016-12-01

    We investigate the stability properties of a collisionless Vlasov plasma in a weakly inhomogeneous magnetic field using non-modal stability analysis. This is an important topic in a physics of tokamak plasma rich in various types of instabilities. We consider a thin tokamak plasma in a Maxwellian equilibrium, subjected to a small arbitrary perturbation. Within the framework of kinetic theory, we demonstrate the emergence of short time scale algebraic instabilities evolving in a stable magnetized plasma. We show that the linearized governing operator (Vlasov operator) is non-normal leading to the transient growth of the perturbations on the time scale of several plasma periods that is subsequently followed by Landau damping. We calculate the first-order distribution function and the electric field and study the dependence of the transient growth characteristics on the magnetic field strength and perturbation parameters of the system. We compare our results with uniformly magnetized plasma and field-free Vlasov plasma.

  14. Effect of radial plasma transport at the magnetic throat on axial ion beam formation

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2016-08-01

    Correlation between radial plasma transport and formation of an axial ion beam has been investigated in a helicon plasma reactor implemented with a convergent-divergent magnetic nozzle. The plasma discharge is sustained under a high magnetic field mode and a low magnetic field mode for which the electron energy probability function, the plasma density, the plasma potential, and the electron temperature are measured at the magnetic throat, and the two field modes show different radial parametric behaviors. Although an axial potential drop occurs in the plasma source for both field modes, an ion beam is only observed in the high field mode while not in the low field mode. The transport of energetic ions is characterized downstream of the plasma source using the delimited ion current and nonlocal ion current. A decay of ion beam strength is also observed in the diffusion chamber.

  15. Role of external magnetic field and current closure in the force balance mechanism of a magnetically stabilized plasma torch

    NASA Astrophysics Data System (ADS)

    G, Ravi; Goyal, Vidhi

    2012-10-01

    Experimental investigations on the role of applied external magnetic field and return current closure in the force balance mechanism of a plasma torch are reported. The plasma torch is of low power and has wall, gas and magnetic stabilization mechanisms incorporated in it. Gas flow is divided into two parts: axial-central and peripheral-shroud, applied magnetic field is axial and return current is co-axial. Results indicate that application of large external magnetic field gives rise to not only J x B force but also, coupled with gas flow, to a new drag-cum-centrifugal force that acts on the plasma arc root and column. The magnetic field also plays a role in the return current closure dynamics and thus in the overall force balance mechanism. This in turn affects the electro-thermal efficiency of the plasma torch. Detailed experimental results, analytical calculations and physical model representing the processes will be presented and discussed.

  16. Behavior of moving plasma in solenoidal magnetic field in a laser ion source.

    PubMed

    Ikeda, S; Takahashi, K; Okamura, M; Horioka, K

    2016-02-01

    In a laser ion source, a solenoidal magnetic field is useful to guide the plasma and to control the extracted beam current. However, the behavior of the plasma drifting in the magnetic field has not been well understood. Therefore, to investigate the behavior, we measured the plasma ion current and the total charge within a single pulse in the solenoid by changing the distance from the entrance of the solenoid to a detector. We observed that the decrease of the total charge along the distance became smaller as the magnetic field became larger and then the charge became almost constant with a certain magnetic flux density. The results indicate that the transverse spreading speed of the plasma decreased with increasing the field and the plasma was confined transversely with the magnetic flux density. We found that the reason of the confinement was not magnetization of ions but an influence induced by electrons.

  17. Behavior of moving plasma in solenoidal magnetic field in a laser ion source

    NASA Astrophysics Data System (ADS)

    Ikeda, S.; Takahashi, K.; Okamura, M.; Horioka, K.

    2016-02-01

    In a laser ion source, a solenoidal magnetic field is useful to guide the plasma and to control the extracted beam current. However, the behavior of the plasma drifting in the magnetic field has not been well understood. Therefore, to investigate the behavior, we measured the plasma ion current and the total charge within a single pulse in the solenoid by changing the distance from the entrance of the solenoid to a detector. We observed that the decrease of the total charge along the distance became smaller as the magnetic field became larger and then the charge became almost constant with a certain magnetic flux density. The results indicate that the transverse spreading speed of the plasma decreased with increasing the field and the plasma was confined transversely with the magnetic flux density. We found that the reason of the confinement was not magnetization of ions but an influence induced by electrons.

  18. Behavior of moving plasma in solenoidal magnetic field in a laser ion source

    SciTech Connect

    Ikeda, S.; Takahashi, K.; Okamura, M.; Horioka, K.

    2016-02-15

    In a laser ion source, a solenoidal magnetic field is useful to guide the plasma and to control the extracted beam current. However, the behavior of the plasma drifting in the magnetic field has not been well understood. Therefore, to investigate the behavior, we measured the plasma ion current and the total charge within a single pulse in the solenoid by changing the distance from the entrance of the solenoid to a detector. We observed that the decrease of the total charge along the distance became smaller as the magnetic field became larger and then the charge became almost constant with a certain magnetic flux density. The results indicate that the transverse spreading speed of the plasma decreased with increasing the field and the plasma was confined transversely with the magnetic flux density. We found that the reason of the confinement was not magnetization of ions but an influence induced by electrons.

  19. Generation of electromagnetic emission during the injection of dense supersonic plasma flows into arched magnetic field

    NASA Astrophysics Data System (ADS)

    Mansfeld, Dmitry; Golubev, Sergey; Viktorov, Mikhail; Vodopyanov, Alexander; Yushkov, George

    2015-11-01

    Interaction of dense supersonic plasma flows with an inhomogeneous arched magnetic field is one of the key problems in near-Earth and space plasma physics. In this work a new experimental approach is suggested to study interaction of supersonic (ion Mach number up to 2.7) dense (up to 1015cm-3) plasma flows with inhomogeneous magnetic field (an arched magnetic trap with a field strength up to 3.3 T) which opens wide opportunities to model space plasma processes in laboratory conditions. Fully ionized plasma flows with density from 1013cm-3 to 1015cm-3 are created by plasma generator on the basis of pulsed vacuum arc discharge and injected into open magnetic trap across magnetic field lines. The filling of the arched magnetic trap with plasma and further magnetic field lines break by dense plasma flow was accompanied by pulsed electromagnetic emission at electron cyclotron frequency range, which can generated by electrons in the place of intensive deceleration of plasma flow in magnetic field. Grant of Ministry of Education 14.Z50.31.0007.

  20. Helicon waves in uniform plasmas. II. High m numbers

    SciTech Connect

    Stenzel, R. L.; Urrutia, J. M.

    2015-09-15

    Helicons are whistler modes with azimuthal wave numbers. They have been studied in solids and plasmas where boundaries play a role. The present work shows that very similar modes exist in unbounded gaseous plasmas. Instead of boundaries, the antenna properties determine the topology of the wave packets. The simplest antenna is a magnetic loop which excites m = 0 or m = 1 helicons depending on whether the dipole moment is aligned parallel or perpendicular to the ambient background magnetic field B{sub 0}. While these low order helicons have been described by J. M. Urrutia and R. L. Stenzel [“Helicon modes in uniform plasmas. I. Low m modes,” Phys. Plasmas 22, 092111 (2015)], the present work focuses on high order modes up to m = 8. These are excited by antenna arrays forming magnetic multipoles. Their wave magnetic field has been measured in space and time in a large and uniform laboratory plasma free of boundary effects. The observed wave topology exhibits m pairs of unique field line spirals which may have inspired the name “helicon” to this mode. All field lines converge into these nested spirals which propagate like corkscrews along B{sub 0}. The field lines near the axis of helicons are perpendicular to B{sub 0} and circularly polarized as in parallel whistlers. Helical antennas couple to these transverse fields but not to the spiral fields of helicons. Using a circular antenna array of phased m = 0 loops, right or left rotating or non-rotating multipole antenna fields are generated. They excite m < 0 and m > 0 modes, showing that the plasma supports both modes equally well. The poor excitation of m < 0 modes is a characteristic of loops with dipole moment across B{sub 0}. The radiation efficiency of multipole antennas has been found to decrease with m.

  1. Helicon waves in uniform plasmas. II. High m numbers

    NASA Astrophysics Data System (ADS)

    Stenzel, R. L.; Urrutia, J. M.

    2015-09-01

    Helicons are whistler modes with azimuthal wave numbers. They have been studied in solids and plasmas where boundaries play a role. The present work shows that very similar modes exist in unbounded gaseous plasmas. Instead of boundaries, the antenna properties determine the topology of the wave packets. The simplest antenna is a magnetic loop which excites m = 0 or m = 1 helicons depending on whether the dipole moment is aligned parallel or perpendicular to the ambient background magnetic field B0. While these low order helicons have been described by J. M. Urrutia and R. L. Stenzel ["Helicon modes in uniform plasmas. I. Low m modes," Phys. Plasmas 22, 092111 (2015)], the present work focuses on high order modes up to m = 8. These are excited by antenna arrays forming magnetic multipoles. Their wave magnetic field has been measured in space and time in a large and uniform laboratory plasma free of boundary effects. The observed wave topology exhibits m pairs of unique field line spirals which may have inspired the name "helicon" to this mode. All field lines converge into these nested spirals which propagate like corkscrews along B0. The field lines near the axis of helicons are perpendicular to B0 and circularly polarized as in parallel whistlers. Helical antennas couple to these transverse fields but not to the spiral fields of helicons. Using a circular antenna array of phased m = 0 loops, right or left rotating or non-rotating multipole antenna fields are generated. They excite m < 0 and m > 0 modes, showing that the plasma supports both modes equally well. The poor excitation of m < 0 modes is a characteristic of loops with dipole moment across B0. The radiation efficiency of multipole antennas has been found to decrease with m.

  2. Effects of magnetic drift tangential to magnetic surfaces on neoclassical transport in non-axisymmetric plasmas

    SciTech Connect

    Matsuoka, Seikichi; Satake, Shinsuke; Kanno, Ryutaro; Sugama, Hideo

    2015-07-15

    In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field E{sub r}. The peaked behavior of the neoclassical radial fluxes around E{sub r }={sub  }0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account.

  3. Effect of electron reflection on magnetized plasma sheath in an oblique magnetic field

    SciTech Connect

    Wang, Ting-Ting; Ma, J. X. Wei, Zi-An

    2015-09-15

    Magnetized plasma sheaths in an oblique magnetic field were extensively investigated by conventionally assuming Boltzmann relation for electron density. This article presents the study of the magnetized sheath without using the Boltzmann relation but by considering the electron reflection along the magnetic field lines caused by the negative sheath potential. A generalized Bohm criterion is analytically derived, and sheath profiles are numerically obtained, which are compared with the results of the conventional model. The results show that the ion Mach number at the sheath edge normal to the wall has a strong dependence on the wall potential, which differs significantly from the conventional model in which the Mach number is independent of the wall potential. The floating wall potential is lower in the present model than that in the conventional model. Furthermore, the sheath profiles are appreciably narrower in the present model when the wall bias is low, but approach the result of the conventional model when the wall bias is high. The sheath thickness decreases with the increase of ion-to-electron temperature ratio and magnetic field strength but has a complex relationship with the angle of the magnetic field.

  4. Induced magnetic-field effects in inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Cohen, Ronald H.; Rognlien, Thomas D.

    1996-05-01

    In inductive plasma sources, the rapid spatial decay of the electric field arising from the skin effect produces a large radio frequency (RF) magnetic field via Faraday's law. It was previously shown that this magnetic field leads to a reduction of the electron density in the skin region, as well as a reduction in the collisionless heating rate. The electron deficit leads to the formation of an electrostatic potential which pulls electrons in to restore quasineutrality. Here the electron density calculation is extended to include both the induced and electrostatic fields. If the wave frequency is not too low, the ions respond only to the averaged fields, and hence the electrostatic field is oscillatory, predominantly at the second harmonic of the applied field. The potential required to establish a constant electron density is calculated and compared with numerical orbit-code calculations. For times short compared to ion transit times, the quasineutral density is just the initial ion density. For timescales long enough that the ions can relax, the density profile can be found from the solution of fluid equations with an effective (ponderomotive-like) potential added. Although the time-varying electrostatic potential is an extra source of heating, the net effect of the induced magnetic and electrostatic fields through trapping, early turning, and direct heating is a significant reduction in collisionless heating for parameters of interest.

  5. Magnetic Field and Plasma Diagnostics from Coordinated Prominence Observations

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Levens, P.; Dalmasse, K.; Mein, N.; Mein, P.; Lopez-Ariste, A.; Labrosse, N.; Heinzel, P.

    2016-04-01

    We study the magnetic field in prominences from a statistical point of view, by using THEMIS in the MTR mode, performing spectropolarimetry of the He I D3 line. Combining these measurements with spectroscopic data from IRIS, Hinode/EIS as well as ground-based telescopes, such as the Meudon Solar Tower, we infer the temperature, density, and flow velocities of the plasma. There are a number of open questions that we aim to answer: - What is the general direction of the magnetic field in prominences? Is the model using a single orientation of magnetic field always valid for atypical prominences? %- Does this depend on the location of the filament on the disk (visible in Hα, in He II 304 Å) over an inversion line between weak or strong network ? - Are prominences in a weak environment field dominated by gas pressure? - Measuring the Doppler shifts in Mg II lines (with IRIS) and in Hα can tell us if there are substantial velocities to maintain vertical rotating structures, as has been suggested for tornado-like prominences. We present here some results obtained with different ground-based and space-based instruments in this framework.

  6. Dufour and Soret effects in a magnetized and nonmagnetized plasma

    SciTech Connect

    Garcia-Colin, L. S.; Garcia-Perciante, A. L.; Sandoval-Villalbazo, A.

    2007-01-15

    It is well known that magnetic fields affect heat conduction in a different way in the direction parallel and perpendicular to the field. In this paper, a formal derivation of this phenomenon and analytical expressions for the transport coefficients based in the Boltzmann equation are presented. Moreover, the Dufour effect or diffusion thermo-effect is usually ignored in plasma transport theory. This effect is shown here to be not only relevant but also the most important source of heat conduction for weak magnetic fields. In this work, analytic expressions for the parallel and perpendicular thermal conductivities as well as the coefficients for both the thermal diffusion, or Soret, effect and the Dufour effect are formally derived. It is also shown how the heat conduction in the perpendicular direction decreases with increasing magnetic field and how in both directions the diffusion thermo-effect is far more important than thermal conduction, leading to a new effective thermal conductivity coefficient. Other aspects of this work are also emphasized.

  7. Induced magnetic-field effects in inductively coupled plasmas

    SciTech Connect

    Cohen, R.H.; Rognlien, T.D.

    1995-11-04

    In inductive plasma sources, the rapid spatial decay of the electric field arising from the skin effect produces a large radio frequency (RF) magnetic field via Faraday`s law. We previously determined that this magnetic field leads to a reduction of the electron density in the skin region, as well as a reduction in the collisionless heating rate. The electron deficit leads to the formation of an electrostatic potential which pulls electrons in to restore quasineutrality. Here we calculate the electron density including both the induced and electrostatic fields. If the wave frequency is not too low, the ions respond only to the averaged fields, and hence the electrostatic field is oscillatory, predominantly at the second harmonic of the applied field. We calculate the potential required to establish a constant electron density, and compare with numerical orbit-code calculations. For times short compared to ion transit times, the quasineutral density is just the initial ion density. For timescales long enough that the ions can relax, the density profile can be found from the solution of fluid equations with an effective (ponderomotive-like) potential added. Although the time-varying electrostatic potential is an extra source of heating, the net effect of the induced magnetic and electrostatic fields through trapping, early turning, and direct heating is a significant reduction in collisionless heating for parameters of interest.

  8. Internal Magnetic Field, Temperature and Density Measurements on Magnetized HED plasmas using Pulsed Polarimetry

    SciTech Connect

    Smith, Roger J.

    2016-10-20

    The goals were to collaborate with the MSX project and make the MSX platform reliable with a performance where pulsed polarimetry would be capable of adding a useful measurement and then to achieve a first measurement using pulsed polarimetry. The MSX platform (outside of laser blow off plasmas adjacent to magnetic fields which are low beta) is the only device that can generate high beta magnetized collisionless supercritical shocks, and with a large spatial size of ~10 cm. Creating shocks at high Mach numbers and investigating the dynamics of the shocks was the main goal of the project. The MSX shocks scale to astrophysical magnetized shocks and potentially throw light on the generation of highly energetic particles via a mechanism like the Fermi process.

  9. Investigation of effect of solenoid magnet on emittances of ion beam from laser ablation plasma

    NASA Astrophysics Data System (ADS)

    Ikeda, Shunsuke; Romanelli, Mark; Cinquegrani, David; Sekine, Megumi; Kumaki, Masafumi; Fuwa, Yasuhiro; Kanesue, Takeshi; Okamura, Masahiro; Horioka, Kazuhiko

    2014-02-01

    A magnetic field can increase an ion current of a laser ablation plasma and is expected to control the change of the plasma ion current. However, the magnetic field can also make some fluctuations of the plasma and the effect on the beam emittance and the emission surface is not clear. To investigate the effect of a magnetic field, we extracted the ion beams under three conditions where without magnetic field, with magnetic field, and without magnetic field with higher laser energy to measure the beam distribution in phase space. Then we compared the relations between the plasma ion current density into the extraction gap and the Twiss parameters with each condition. We observed the effect of the magnetic field on the emission surface.

  10. Investigation of effect of solenoid magnet on emittances of ion beam from laser ablation plasma.

    PubMed

    Ikeda, Shunsuke; Romanelli, Mark; Cinquegrani, David; Sekine, Megumi; Kumaki, Masafumi; Fuwa, Yasuhiro; Kanesue, Takeshi; Okamura, Masahiro; Horioka, Kazuhiko

    2014-02-01

    A magnetic field can increase an ion current of a laser ablation plasma and is expected to control the change of the plasma ion current. However, the magnetic field can also make some fluctuations of the plasma and the effect on the beam emittance and the emission surface is not clear. To investigate the effect of a magnetic field, we extracted the ion beams under three conditions where without magnetic field, with magnetic field, and without magnetic field with higher laser energy to measure the beam distribution in phase space. Then we compared the relations between the plasma ion current density into the extraction gap and the Twiss parameters with each condition. We observed the effect of the magnetic field on the emission surface.

  11. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  12. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect

    Rosenberg, M. J. Li, C. K.; Séguin, F. H.; Frenje, J. A.; Petrasso, R. D.; Fox, W.; Igumenshchev, I.; Stoeckl, C.; Glebov, V.; Town, R. P. J.

    2015-04-15

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β ∼ 10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  13. Bondi-Hoyle Accretion in an Isothermal Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Lee, Aaron T.; Cunningham, Andrew J.; McKee, Christopher F.; Klein, Richard I.

    2014-03-01

    In regions of star formation, protostars and newborn stars will accrete mass from their natal clouds. These clouds are threaded by magnetic fields with a strength characterized by the plasma β—the ratio of thermal and magnetic pressures. Observations show that molecular clouds have β <~ 1, so magnetic fields have the potential to play a significant role in the accretion process. We have carried out a numerical study of the effect of large-scale magnetic fields on the rate of accretion onto a uniformly moving point particle from a uniform, non-self-gravitating, isothermal gas. We consider gas moving with sonic Mach numbers of up to {\\cal M}\\approx 45; magnetic fields that are either parallel, perpendicular, or oriented 45° to the flow; and β as low as 0.01. Our simulations utilize adaptive mesh refinement in order to obtain high spatial resolution where it is needed; this also allows the boundaries to be far from the accreting object to avoid unphysical effects arising from boundary conditions. Additionally, we show that our results are independent of our exact prescription for accreting mass in the sink particle. We give simple expressions for the steady-state accretion rate as a function of β and {\\cal M} for the parallel and perpendicular orientations. Using typical molecular cloud values of {\\cal M}\\sim 5 and β ~ 0.04 from the literature, our fits suggest that a 0.4 M ⊙ star accretes ~4 × 10-9 M ⊙ yr-1, almost a factor of two less than accretion rates predicted by hydrodynamic models. This disparity can grow to orders of magnitude for stronger fields and lower Mach numbers. We also discuss the applicability of these accretion rates versus accretion rates expected from gravitational collapse, and under what conditions a steady state is possible. The reduction in the accretion rate in a magnetized medium leads to an increase in the time required to form stars in competitive accretion models, making such models less efficient than predicted by

  14. Bondi-Hoyle accretion in an isothermal magnetized plasma

    SciTech Connect

    Lee, Aaron T.; McKee, Christopher F.; Klein, Richard I.; Cunningham, Andrew J.

    2014-03-01

    In regions of star formation, protostars and newborn stars will accrete mass from their natal clouds. These clouds are threaded by magnetic fields with a strength characterized by the plasma β—the ratio of thermal and magnetic pressures. Observations show that molecular clouds have β ≲ 1, so magnetic fields have the potential to play a significant role in the accretion process. We have carried out a numerical study of the effect of large-scale magnetic fields on the rate of accretion onto a uniformly moving point particle from a uniform, non-self-gravitating, isothermal gas. We consider gas moving with sonic Mach numbers of up to M≈45; magnetic fields that are either parallel, perpendicular, or oriented 45° to the flow; and β as low as 0.01. Our simulations utilize adaptive mesh refinement in order to obtain high spatial resolution where it is needed; this also allows the boundaries to be far from the accreting object to avoid unphysical effects arising from boundary conditions. Additionally, we show that our results are independent of our exact prescription for accreting mass in the sink particle. We give simple expressions for the steady-state accretion rate as a function of β and M for the parallel and perpendicular orientations. Using typical molecular cloud values of M∼5 and β ∼ 0.04 from the literature, our fits suggest that a 0.4 M {sub ☉} star accretes ∼4 × 10{sup –9} M {sub ☉} yr{sup –1}, almost a factor of two less than accretion rates predicted by hydrodynamic models. This disparity can grow to orders of magnitude for stronger fields and lower Mach numbers. We also discuss the applicability of these accretion rates versus accretion rates expected from gravitational collapse, and under what conditions a steady state is possible. The reduction in the accretion rate in a magnetized medium leads to an increase in the time required to form stars in competitive accretion models, making such models less efficient than predicted by

  15. 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.

  16. Slowing of magnetic reconnection concurrent with weakening plasma inflows and increasing collisionality in strongly-driven laser-plasma experiments

    SciTech Connect

    Rosenberg, M.  J.; Li, C.  K.; Fox, W.; Zylstra, A.  B.; Stoeckl, C.; Séguin, F.  H.; Frenje, J.  A.; Petrasso, R. D.

    2015-05-20

    An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly-driven, β ≲ 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely-directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-Alfvénic electron jets (Vjet~ 20VA) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early in time. The absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly-driven regime.

  17. Investigation of MHD Instabilities in Jets and Bubbles Using a Compact Coaxial Plasma Gun in a Background Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Fisher, D. M.; Wallace, B.; Gilmore, M.; Hsu, S. C.

    2016-10-01

    A compact coaxial plasma gun is employed for experimental investigation of launching plasma into a lower density background magnetized plasma. Experiments are being conducted in the linear device HelCat at UNM. Four distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. For regime I plasma jet formation, a global helical magnetic configuration is determined by a B-dot probe array data. Also the m =1 kink instability is observed and verified. Furthermore, when the jet is propagating into background magnetic field, a longer length and lifetime jet is formed. Axial shear flow caused by the background magnetic tension force contributes to the increased stability of the jet body. In regime II, a spheromak-like plasma bubble formation is identified when the gun plasma is injected into vacuum. In contrast, when the bubble propagates into a background magnetic field, the closed magnetic field configuration does not hold anymore and a lateral side, Reilgh-Taylor instability develops. Detailed experimental data and analysis will be presented for these cases.

  18. Slowing of magnetic reconnection concurrent with weakening plasma inflows and increasing collisionality in strongly-driven laser-plasma experiments

    DOE PAGES

    Rosenberg, M.  J.; Li, C.  K.; Fox, W.; ...

    2015-05-20

    An evolution of magnetic reconnection behavior, from fast jets to the slowing of reconnection and the establishment of a stable current sheet, has been observed in strongly-driven, β ≲ 20 laser-produced plasma experiments. This process has been inferred to occur alongside a slowing of plasma inflows carrying the oppositely-directed magnetic fields as well as the evolution of plasma conditions from collisionless to collisional. High-resolution proton radiography has revealed unprecedented detail of the forced interaction of magnetic fields and super-Alfvénic electron jets (Vjet~ 20VA) ejected from the reconnection region, indicating that two-fluid or collisionless magnetic reconnection occurs early in time. Themore » absence of jets and the persistence of strong, stable magnetic fields at late times indicates that the reconnection process slows down, while plasma flows stagnate and plasma conditions evolve to a cooler, denser, more collisional state. These results demonstrate that powerful initial plasma flows are not sufficient to force a complete reconnection of magnetic fields, even in the strongly-driven regime.« less

  19. The different evolution of plasma density voids and blobs in the edge region of a simply magnetized toroidal plasma

    NASA Astrophysics Data System (ADS)

    Barni, R.; Caldirola, S.; Fattorini, L.; Riccardi, C.

    2017-03-01

    The analysis of the anomalous transport in magnetised plasmas has pointed out the substantial contribution of intermittent burst events corresponding to positive density fluctuations propagating outwards to the edges of the devices. Much less attention was paid to negative density fluctuation structures, which could be named depletions or voids, whose propagation could contribute to the global anomalous transport, in particular, when a non-negligible diffuse plasma background is present in magnetized plasma device edges. Here, we discuss the results of an experimental investigation aimed to study the spatio-temporal evolution of density depletion structures propagating inwards in a magnetized plasma column simply magnetized toroidal device. Evidence of this behavior was gathered by a conditional sampling analysis applied to time series of plasma fluctuations. We observe that a significant fraction of void structures, after being ejected outside the main plasma column, gets pulled inwards and disappears by merging at the column edge. On the other hand, a smaller fraction as well as most of the positive density structures, after ejection, ends up advected towards the edges of the device and gets lost from the main plasma column. These behaviors testify the richness and complexity of density structure evolution in magnetized plasma turbulence.

  20. Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory

    NASA Astrophysics Data System (ADS)

    Schlickeiser, R.; Yoon, P. H.

    2015-07-01

    Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.

  1. Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory

    SciTech Connect

    Schlickeiser, R. E-mail: yoonp@umd.edu; Yoon, P. H. E-mail: yoonp@umd.edu

    2015-07-15

    Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.

  2. Experimental investigation of discharge plasma magnetic confinement in the NSTASR ion thruster

    NASA Technical Reports Server (NTRS)

    Sengupta, Anita; Fitzgerald, Dennis; Owens, Al

    2005-01-01

    Magnetic confinement studies were performed on the state-of-the-art NSTAR ion thruster. The goal of the experimental studies was determine the dependence of plasma confinement and plasma uniformity on the strength and shape of the imposed ring-cusp magnetic field.

  3. An overview of fast multipole methods

    SciTech Connect

    Strickland, J.H.; Baty, R.S.

    1995-11-01

    A number of physics problems may be cast in terms of Hilbert-Schmidt integral equations. In many cases, the integrals tend to be zero over a large portion of the domain of interest. All of the information is contained in compact regions of the domain which renders their use very attractive from the standpoint of efficient numerical computation. Discrete representation of these integrals leads to a system of N elements which have pair-wise interactions with one another. A direct solution technique requires computational effort which is O(N{sup 2}). Fast multipole methods (FMM) have been widely used in recent years to obtain solutions to these problems requiring a computational effort of only O(Nln N) or O(N). In this paper we present an overview of several variations of the fast multipole method along with examples of its use in solving a variety of physical problems.

  4. Magnetic shield for turbomolecular pump of the Magnetized Plasma Linear Experimental device at Saha Institute of Nuclear Physics.

    PubMed

    Biswas, Subir; Chattopadhyay, Monobir; Pal, Rabindranath

    2011-01-01

    The turbo molecular pump of the Magnetized Plasma Linear Experimental device is protected from damage by a magnetic shield. As the pump runs continuously in a magnetic field environment during a plasma physics experiment, it may get damaged owing to eddy current effect. For design and testing of the shield, first we simulate in details various aspects of magnetic shield layouts using a readily available field design code. The performance of the shield made from two half cylinders of soft iron material, is experimentally observed to agree very well with the simulation results.

  5. Three-dimensional, Impulsive Magnetic Reconnection in a Laboratory Plasma

    SciTech Connect

    S Dorfman, et al

    2013-05-03

    Impulsive, local, 3-D reconnection is identified for the first time in a laboratory current sheet. The events observed in the Magnetic Reconnection Experiment (MRX) are characterized by large local gradients in the third direction and cannot be explained by 2-D models. Detailed measurements show that the ejection of flux rope structures from the current sheet plays a key role in these events. By contrast, even though electromagnetic fluctuations in the lower hybrid frequency range are also observed concurrently with the impulsive behavior, they are not the key physics responsible. A qualitative, 3-D, two-fluid model is proposed to explain the observations. The experimental results may be particularly applicable to space and astrophysical plasmas where impulsive reconnection occurs.

  6. Kinetic theory of a two-dimensional magnetized plasma.

    NASA Technical Reports Server (NTRS)

    Vahala, G.; Montgomery, D.

    1971-01-01

    Several features of the equilibrium and nonequilibrium statistical mechanics of a two-dimensional plasma in a uniform dc magnetic field are investigated. The charges are assumed to interact only through electrostatic potentials. The problem is considered both with and without the guiding-center approximation. With the guiding-center approximation, an appropriate Liouville equation and BBGKY hierarchy predict no approach to thermal equilibrium for the spatially uniform case. For the spatially nonuniform situation, a guiding-center Vlasov equation is discussed and solved in special cases. For the nonequilibrium, nonguiding-center case, a Boltzmann equation, and a Fokker-Planck equation are derived in the appropriate limits. The latter is more tractable than the former, and can be shown to obey conservation laws and an H-theorem, but contains a divergent integral which must be cut off on physical grounds. Several unsolved problems are posed.

  7. Solitary perturbations in the steep boundary of magnetized toroidal plasma

    PubMed Central

    Lee, J. E.; Yun, G. S.; Lee, W.; Kim, M. H.; Choi, M.; Lee, J.; Kim, M.; Park, H. K.; Bak, J. G.; Ko, W. H.; Park, Y. S.

    2017-01-01

    Solitary perturbations (SPs) localized both poloidally and radially are detected within ~100 μs before the partial collapse of the high pressure gradient boundary region (called pedestal) of magnetized toroidal plasma in the KSTAR tokamak device. The SP develops with a low toroidal mode number (typically unity) in the pedestal ingrained with quasi-stable edge-localized mode (QSM) which commonly appears during the inter-collapse period. The SPs have smaller mode pitch and different (often opposite) rotation velocity compared to the QSMs. Similar solitary perturbations are also frequently observed before the onset of complete pedestal collapse, suggesting a strong connection between the SP generation and the pedestal collapse. PMID:28338046

  8. Tunable Circularly Polarized Terahertz Radiation from Magnetized Gas Plasma.

    PubMed

    Wang, W-M; Gibbon, P; Sheng, Z-M; Li, Y-T

    2015-06-26

    It is shown, by simulation and theory, that circularly or elliptically polarized terahertz radiation can be generated when a static magnetic (B) field is imposed on a gas target along the propagation direction of a two-color laser driver. The radiation frequency is determined by √[ω(p)(2)+ω(c)(2)/4]+ω(c)/2, where ω(p) is the plasma frequency and ω(c) is the electron cyclotron frequency. With the increase of the B field, the radiation changes from a single-cycle broadband waveform to a continuous narrow-band emission. In high-B-field cases, the radiation strength is proportional to ω(p)(2)/ω(c). The B field provides a tunability in the radiation frequency, spectrum width, and field strength.

  9. Numerical evaluation of external magnetic effect on electromagnetic wave transmission through reentry plasma layer

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Bo, Yong; Lei, Mingda; Liu, Shuzhang; Liu, Ying; Liu, Jianwei; Zhao, Yizhe

    2016-11-01

    Numerical study of electromagnetic (EM) wave transmission through the magnetized plasma layer is presented in this paper. The plasma parameters are derived from computational fluid dynamics simulation of the flow field around a blunt body flying at supersonic speed and serve as the background plasma condition in the numerical modeling for EM wave transmission. The EM wave is generated by our newly designed coaxial feed GPS patch antenna. The external magnetic field is applied and assumed to vary linearly as a function of wall distance. The effects of the external applied magnetic field and the plasma parameters on wave transmission are studied, and the results show that EM wave propagation in the non-uniformly magnetized plasma is a matter of impedance matching, and the EM wave transmission can be adjusted only when the proper strength of the magnetic field is applied.

  10. Relativistic wave-induced splitting of the Langmuir mode in a magnetized plasma.

    PubMed

    Robiche, J; Rax, J M

    2008-01-01

    A relativistic effect that occurs in a magnetized plasma irradiated by a circularly polarized wave is identified and analyzed: the usual plasma frequency associated with longitudinal oscillations splits into two new frequencies. We set up a Hamiltonian description of the plasma dynamic in order to identify this effect that results from the coupling between the plasma oscillation and the transverse circular motion driven by both the magnetic and wave fields. Within the small oscillations approximation, we compute for right- and left-handed polarization the two characteristics frequencies of the electron oscillations as functions of the field and wave parameters. We also describe the electron trajectories in the wave, magnetic, and restoring plasma fields. This new class of oscillations is rotational and therefore radiate suggesting a method for the diagnostics of strong static magnetic field in laser-plasma experiments.

  11. Method of reducing multipole content in a conductor assembly during manufacture

    SciTech Connect

    Meinke, Rainer

    2013-08-20

    A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departs from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.

  12. Method of reducing multipole content in a conductor assembly during manufacture

    SciTech Connect

    Meinke, Rainer

    2016-05-24

    A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departs from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.

  13. Method of reducing multipole content in a conductor assembly during manufacture

    DOEpatents

    Meinke, Rainer

    2011-08-09

    A method for manufacture of a conductor assembly. The assembly is of the type which, when conducting current, generates a magnetic field or in which, in the presence of a changing magnetic field, a voltage is induced. In an example embodiment one or more first coil rows are formed. The assembly has multiple coil rows about an axis with outer coil rows formed about inner coil rows. A determination is made of deviations from specifications associated with the formed one or more first coil rows. One or more deviations correspond to a magnitude of a multipole field component which departs from a field specification. Based on the deviations, one or more wiring patterns are generated for one or more second coil rows to be formed about the one or more first coil rows. The one or more second coil rows are formed in the assembly. The magnitude of each multipole field component that departs from the field specification is offset.

  14. Optimization of RF multipole ion trap geometries

    NASA Astrophysics Data System (ADS)

    Fanghänel, Sven; Asvany, Oskar; Schlemmer, Stephan

    2017-02-01

    Radio-frequency (rf) traps are ideal places to store cold ions for spectroscopic experiments. Specific multipole configurations are suited best for different applications but have to be modified to allow e.g. for a proper overlap of a laser beam waist with the ion cloud. Therefore the corresponding trapping fields should be shaped accordingly. To achieve this goal highly accurate electrical potentials of rf multipole traps and the resulting effective trapping potentials are calculated using the boundary element method (BEM). These calculations are used to evaluate imperfections and to optimize the field geometry. For that purpose the complex fields are reduced to a small set of multipole expansion coefficients. Desirable values for these coefficients are met by systematic changes of real trap dimensions from CAD designs. The effect of misalignment of a linear quadrupole, the optimization of an optically open Paul trap, the influence of steering electrodes (end electrode and ring electrode) on a 22-pole ion trap and the effect of the micro motion on the lowest reachable temperatures in such a trap are discussed.

  15. Method and means for measuring the anisotropy of a plasma in a magnetic field

    DOEpatents

    Shohet, J.L.; Greene, D.G.S.

    1973-10-23

    Anisotropy is measured of a free-free-bremsstrahlungradiation-generating plasma in a magnetic field by collimating the free-free bremsstrahlung radiation in a direction normal to the magnetic field and scattering the collimated free- free bremsstrahlung radiation to resolve the radiation into its vector components in a plane parallel to the electric field of the bremsstrahlung radiation. The scattered vector components are counted at particular energy levels in a direction parallel to the magnetic field and also normal to the magnetic field of the plasma to provide a measure of anisotropy of the plasma. (Official Gazette)

  16. Generation and evolution of magnetic field in the relativistic plasma following q-nonextensive distribution

    NASA Astrophysics Data System (ADS)

    Lin, Fu-Jun; Chen, Zong-Hua; Li, Xiao-Qing; Liao, Jing-Jing; Zhu, Yun

    2017-02-01

    A GigaGauss quasi-steady magnetic field can be generated in astrophysical plasmas and laser-produced plasmas with high-frequency electromagnetic radiation through wave-wave and wave-particle interactions. A set of governing equations for this field are obtained in the plasma consisting of ultra-relativistic electrons following q-nonextensive distribution. The numerical results show that the initial field is unstable and can collapse to generate various spatially intermittent magnetic flux tubes. It can also be found that the behavior of the magnetic field is greatly dependent on the nonextensive index q, which may be helpful in understanding the magnetic turbulence.

  17. Combined effects of ambient gas pressures and magnetic field on laser plasma expansion dynamics

    NASA Astrophysics Data System (ADS)

    Atif, Hussain; Xun, Gao; Qi, Li; Zuoqiang, Hao; Jingquan, Lin

    2017-01-01

    In this work, we investigated the influence of air gas pressures on the expansion features of nanosecond laser ablated aluminum plasma in the absence and presence of a nonuniform magnetic field using fast photography. A particular emphasis was given to the plume dynamics (shape, size) with the combined effects of ambient gas pressures and an external magnetic field. Free expansion, sharpening effect, and hemi-spherical structures of the aluminum plasma were observed without a magnetic field under different gas pressures. Analysis of the resulting plume images with the combined effects of air gas pressures and a magnetic field show significant changes, such as plume splitting, elliptical geometry changes, radial expansion, and plume confinement. Furthermore, the total size of the plasma plume with a magnetic field was measured to be smaller than the plasma plume without a magnetic field at several background pressures.

  18. Detailed Analysis Case Studies of Trapped Plasmas at the Earth’s Magnetic Equator

    DTIC Science & Technology

    1993-06-01

    5 Figure 2. Plasma Density L Dependance ...... ......... 7 Figure 3. Plasmapause Magnetic Activity Dependance . . 8 Figure 4. Plasma Density L... Dependance - Normalized . . 10 Figure 5. The Dusk Bulge . . . .............. 13 Figure 6. Magnetosphere’s Electric and Magnetic Fields 14 Figure 7...1970). 6 -. ~ .ZJ.:AUGUST 12,1968 . -. ----- OUTBOUND PASS - 2 3 4 5 ___ ... 7....9 L Figure 2. Plasma Density L Dependance 7 0D3 #n /2 OUT JND tN

  19. Runaway electrons in a magnetized plasma in an rf electric field

    SciTech Connect

    Razdorskii, V.G.

    1982-01-01

    Runaway electrons may appear during electron-cyclotron heating of a plasma. In a constant magnetic field crossed with an rf electric field an effective acceleration of plasma electrons across the magnetic field takes place. When Coulomb collisions are taken into account, this acceleration gives rise to a stream of runaway electrons. The current in this stream is determined as a function of the amplitude of the electric field and the plasma parameters.

  20. Electrostatic turbulence and transport in a simple magnetized plasma

    SciTech Connect

    Fasoli, A.; Labit, B.; McGrath, M.; Mueller, S.H.; Plyushchev, G.; Podesta, M.; Poli, F.M.

    2006-05-15

    Gradient driven electrostatic instabilities are investigated in TORPEX [A. Fasoli, B. Labit, M. McGrath, S. H. Mueller, M. Podesta, and F. M. Poli, Bull. Am. Phys. Soc. 48, 119 (2003)], a toroidal device (R=1 m, a=0.2 m) in which plasmas are produced by microwaves (P{<=}20 kW) with f{sub rf}=2.45 GHz, in the electron cyclotron frequency range. Typical density and temperature are n{sub e}{<=}10{sup 17} m{sup -3} and T{sub e}{approx_equal}5 eV, respectively. The magnetic field is mainly toroidal ({<=}0.1 T), with a small vertical component ({<=}4 mT). Instabilities that can be generally identified as drift-interchange waves are observed and characterized for different levels of collisionality with neutrals. The frequency spectrum and the spatial profile of the fluctuation-induced flux are measured. An 86-tip probe is used to reconstruct the spatio-temporal evolution of density structures across the plasma cross section. The measured structures are characterized statistically, and related quantitative observables are constructed.