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Sample records for active magnetospheric particle

  1. Magnetospheric particle populations.

    NASA Technical Reports Server (NTRS)

    Vette, J. I.

    1972-01-01

    Significant results of magnetospheric charged particle measurements conducted within the past two years are reviewed in an attempt to provide a general description of relationships among particle populations in the magnetosheath, plasma sheet, extraterrestrial ring current region, electron trough, pseudotrapping region, and stable-trapping region. Special attention is given to the characteristics of protons, electrons, alpha particles, and particles with charge greater than three in the stable trapping region.

  2. Particle transport in planetary magnetospheres

    SciTech Connect

    Birmingham, T.J.

    1984-11-01

    Particle energization in Earth's and Jupiter's magnetospheres is discussed. Understanding of the large scale magnetic and electric fields in which charged particles move is reviewed. Orbit theory in the adiabatic approximation is sketched. General conditions for adiabatic breakdown at each of three levels of periodicity are presented. High energy losses and lower energy sources argue for the existence of magnetospheric accelerations. Nonadiabatic acceleration processes are mentioned. Slow diffusive energization by particle interactions with electromagnetic fluctuations is outlined. This mechanism seems adequate at Earth but, operating alone, is unconvincing for Jupiter. Adding spatial diffusion in the radially distended Jovian magnetodisk may resolve the difficulty. (ESA)

  3. Particle acceleration in pulsar magnetospheres

    NASA Technical Reports Server (NTRS)

    Baker, K. B.

    1978-01-01

    The structure of pulsar magnetospheres and the acceleration mechanism for charged particles in the magnetosphere was studied using a pulsar model which required large acceleration of the particles near the surface of the star. A theorem was developed which showed that particle acceleration cannot be expected when the angle between the magnetic field lines and the rotation axis is constant (e.g. radial field lines). If this angle is not constant, however, acceleration must occur. The more realistic model of an axisymmetric neutron star with a strong dipole magnetic field aligned with the rotation axis was investigated. In this case, acceleration occurred at large distances from the surface of the star. The magnitude of the current can be determined using the model presented. In the case of nonaxisymmetric systems, the acceleration is expected to occur nearer to the surface of the star.

  4. First Observations of a Foreshock Bubble at Earth: Implications for Magnetospheric Activity and Energetic Particle Acceleration

    NASA Technical Reports Server (NTRS)

    Turner, D. L.; Omidi, N.; Sibeck, D. G.; Angelopoulos, V.

    2011-01-01

    Earth?s foreshock, which is the quasi-parallel region upstream of the bow shock, is a unique plasma region capable of generating several kinds of large-scale phenomena, each of which can impact the magnetosphere resulting in global effects. Interestingly, such phenomena have also been observed at planetary foreshocks throughout our solar system. Recently, a new type of foreshock phenomena has been predicted: foreshock bubbles, which are large-scale disruptions of both the foreshock and incident solar wind plasmas that can result in global magnetospheric disturbances. Here we present unprecedented, multi-point observations of foreshock bubbles at Earth using a combination of spacecraft and ground observations primarily from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, and we include detailed analysis of the events? global effects on the magnetosphere and the energetic ions and electrons accelerated by them, potentially by a combination of first and second order Fermi and shock drift acceleration processes. This new phenomena should play a role in energetic particle acceleration at collisionless, quasi-parallel shocks throughout the Universe.

  5. Particle behavior in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Wolf, R. A.; Spiro, R. W.

    1985-01-01

    The Rice Convection Model deals with large-scale processes in the earth's inner and middle magnetosphere, including coupling to the ionosphere. Starting from appropriate initial and boundary conditions, the model computes the following physical parameters: ionospheric electric fields and currents; magnetospheric particle distributions, electric fields, and electric currents; and magnetic-field-aligned (Birkeland) currents connecting the two regions. This paper evaluates work on the model, with emphasis on the assumptions made, the basic equations, and the numerical methods. The theoretical basis of the model is compared and contrasted with standard magnetohydrodynamics. The limitations imposed by the major assumptions are discussed. Model inputs and boundary conditions are listed, and the methods of specifying them discussed. Some physical conclusions and insights that have been gained from the model are listed and described very briefly. References are given to published discussions of the major points of physics.

  6. Particle simulations in magnetospheric plasmas

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi

    1990-01-01

    In view of the recent remarkable advancement of computer technology and simulation software, simulation studies are one of the most powerful academic tools for establishment of quantitative space physics and modelling of our space environment. The complex nature encountered in space plasma physics has motivated considerable development in computer simulations, which have played an essential role in the development of space plasma theory. This report describes research undertaken to understand physical processes involved in plasma waves observed in the magnetospheric plasmas, and associated nonlinear phenomena such as heating, diffusion, and acceleration of particles due to excited waves. The research explains and clarifies the observational data both qualitatively and quantitatively.

  7. Particles generation and cooling of pulsar magnetosphere

    NASA Astrophysics Data System (ADS)

    Kryvdyk, Volodymyr

    2016-07-01

    The generation of secondary particles (neutrinos, neutrons, electrons, protons, mesons) and gamma-ray photons because of nuclear interactions in magnetospheres of pulsars and magnetars are considered. By means of the nuclear interactions, the primarily accelerated electrons and protons in the pulsar magnetosphere will be generated secondary particles and photons, which will also generate particles and gamma-ray photons by cascading interactions. Namely from these particles and photons, which arise because of multiple interactions, and will consist of the pulsar magnetosphere. It is important that in pulsar magnetosphere will generate the powerful flux of neutral particles (neutrons) and a neutrino that do not interact with the magnetic field and are free to go out with her, bringing out energy and cooling magnetosphere. So, we obtain a powerful new channel cooling pulsar magnetosphere. This is a new result, which shows that cooling of pulsar and magnetars is not only a result of the processes generating neutrinos in the inner core, but also due to the generation of neutrino and neutrons in the pulsar magnetosphere and subsequently their exit in the interstellar environment.

  8. Energetic solar particle behaviour in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Scholer, M.

    1979-01-01

    The behavior of energetic solar flare particles in the magnetosphere is discussed. In the absence of magnetospheric motion, the problem of particle transport can be treated as simple propagation of charged particles in a stationary magnetic field configuration using, for instance, trajectory calculations in model fields. This single particle approach is the basis for the determination of intensity and anisotropy structures over the polar caps and in the geomagnetic tail from different interplanetary conditions. Particle transport on closed field lines is in addition strongly affected by resonant interaction processes as pitch angle scattering and radial diffusion.

  9. Automated Survey of Particle Injections Into the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Sotirelis, T.; Gkioulidou, M.; Mitchell, D. G.; Lanzerotti, L. J.

    2015-12-01

    Energetic particle injections associated with depolarizations have been seen for many years in the magnetotail and at geosynchronous orbit. Now, with Van Allen Probes we see similar signatures in the inner magnetosphere. However, boundary crossings can be mistaken for injection signatures seen only in particle observations. An automated analysis identifies particle injections into the inner magnetosphere in Van Allen Probes RBSPICE observations. Particle injections are distinguished from boundary crossings by through consideration of auxiliary observations. Dispersed injections are distinguished from undispersed injections and the spatial distributions for both are presented. Occurrence frequency as a function of activity is also presented.

  10. Charged particle periodicity in the Saturnian magnetosphere

    NASA Technical Reports Server (NTRS)

    Carbary, J. F.; Krimigis, S. M.

    1982-01-01

    The present investigation is concerned with the first definitive evidence for charged particle modulations near the magnetic rotation period at Saturn. This periodicity is apparent in the ratios (and spectra) of low energy charged particles in the Saturnian magnetosphere. Most of the data presented were taken during the Voyager 2 outbound portion of the Saturn encounter. During this time the spacecraft was at high latitudes (approximately 30 deg) in the southern hemisphere of the Saturnian magnetosphere. The probe's trajectory was approximately along the dawn meridian at an essentially constant local time. The observation that the charged particle modulation is consistent with the Saturn Kilometric Radiation (SKR) period provides a basic input for the resolution of a puzzle which has existed ever since the discovery of the SKR modulation. The charged particle periodicity identified suggests that a basic asymmetry must exist in the Saturnian magnetosphere.

  11. Solar Energetic Particles Trapping in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Engel, M.; Larsen, B. A.

    2011-12-01

    Solar energetic particles (SEPs) are protons, electrons, and heavy ions emitted from the Sun with energies spanning tens of keV to GeV. They are episodic and associated with energetic events at the Sun such as coronal mass ejections. Importantly, they can be injected into and trapped by the Earth's magnetosphere, forming transient new, intense radiation belts that can severely damage components of our space infrastructure and cause significant backgrounds in instruments on national security and other payloads. Our goal is to understand the conditions under which SEPs become trapped and untrapped in the magnetosphere, how trapping depends on the energy distribution of the trapped particles, and if we can predict the location and persistence of these new radiation belts. Previous studies have shown how trapping can occur for individual shock-driven events but do not explore the overall magnetospheric conditions that can lead to SEP trapping and cannot predict trapped population energy spectra, location, or provide a probabilistic model trapping likelihood. Using events spanning 10 years, we will correlate the magnetospheric conditions that affect trapping and dumping. The results of this study will attempt to answer the questions: What fraction of injected SEPs are trapped,forming new, persistent radiation belts? Is there a geomagnetic field preconditioning required for injected SEPs to be trapped or untrapped? What does the energy distribution of injected SEPs relative to their trapped distribution tell us about the underlying physics of trapping? What is the probability of trapping injected SEPs based on different magnetospheric conditions, and can we use this probability as a predictive tool?

  12. Planetary Magnetosphere Probed by Charged Dust Particles

    NASA Astrophysics Data System (ADS)

    Sternovsky, Z.; Horanyi, M.; Gruen, E.; Srama, R.; Auer, S.; Kempf, S.; Krueger, H.

    2010-12-01

    In-situ and remote sensing observations combined with theoretical and numerical modeling greatly advanced our understanding planetary magnetospheres. Dust is an integral component of the Saturnian and Jovian magnetospheres where it can act as a source/sink of plasma particles (dust particles are an effective source for plasma species like O2, OH, etc. through sputtering of ice particles, for example); its distribution is shaped by electrodynamic forces coupled radiation pressure, plasma, and neutral drag, for example. The complex interaction can lead to unusual dust dynamics, including the transport, capture, and ejection of dust grains. The study of the temporal and spatial evolution of fine dust within or outside the magnetosphere thus provides a unique way to combine data from a large number of observations: plasma, plasma wave, dust, and magnetic field measurements. The dust detectors on board the Galileo and Cassini spacecrafts lead to major discoveries, including the jovian dust stream originating from Io or the in-situ sampling and analysis of the plumes of Enceladus. Recent advancement in dust detector technology enables accurate measurement of the dust trajectory and elemental composition that can greatly enhance the understanding of dust magnetorspheric interaction and indentify the source of the dust with high precision. The capabilities of a modern dust detector thus can provide support for the upcoming Europa Jupiter System Mission.

  13. Particle Acceleration in Dissipative Pulsar Magnetospheres

    NASA Technical Reports Server (NTRS)

    Kazanas, Z.; Kalapotharakos, C.; Harding, A.; Contopoulos, I.

    2012-01-01

    Pulsar magnetospheres represent unipolar inductor-type electrical circuits at which an EM potential across the polar cap (due to the rotation of their magnetic field) drives currents that run in and out of the polar cap and close at infinity. An estimate ofthe magnitude of this current can be obtained by dividing the potential induced across the polar cap V approx = B(sub O) R(sub O)(Omega R(sub O)/c)(exp 2) by the impedance of free space Z approx eq 4 pi/c; the resulting polar cap current density is close to $n {GJ} c$ where $n_{GJ}$ is the Goldreich-Julian (GJ) charge density. This argument suggests that even at current densities close to the GJ one, pulsar magnetospheres have a significant component of electric field $E_{parallel}$, parallel to the magnetic field, a condition necessary for particle acceleration and the production of radiation. We present the magnetic and electric field structures as well as the currents, charge densities, spin down rates and potential drops along the magnetic field lines of pulsar magnetospheres which do not obey the ideal MHD condition $E cdot B = 0$. By relating the current density along the poloidal field lines to the parallel electric field via a kind of Ohm's law $J = sigma E_{parallel}$ we study the structure of these magnetospheres as a function of the conductivity $sigma$. We find that for $sigma gg OmegaS the solution tends to the (ideal) Force-Free one and to the Vacuum one for $sigma 11 OmegaS. Finally, we present dissipative magnetospheric solutions with spatially variable $sigma$ that supports various microphysical properties and are compatible with the observations.

  14. PICsar: Particle in cell pulsar magnetosphere simulator

    NASA Astrophysics Data System (ADS)

    Belyaev, Mikhail A.

    2016-07-01

    PICsar simulates the magnetosphere of an aligned axisymmetric pulsar and can be used to simulate other arbitrary electromagnetics problems in axisymmetry. Written in Fortran, this special relativistic, electromagnetic, charge conservative particle in cell code features stretchable body-fitted coordinates that follow the surface of a sphere, simplifying the application of boundary conditions in the case of the aligned pulsar; a radiation absorbing outer boundary, which allows a steady state to be set up dynamically and maintained indefinitely from transient initial conditions; and algorithms for injection of charged particles into the simulation domain. PICsar is parallelized using MPI and has been used on research problems with ~1000 CPUs.

  15. Observation of particle acceleration in laboratory magnetosphere

    SciTech Connect

    Kawazura, Y.; Yoshida, Z.; Nishiura, M.; Saitoh, H.; Yano, Y.; Nogami, T.; Sato, N.; Yamasaki, M.; Kashyap, A.; Mushiake, T.

    2015-11-15

    The self-organization of magnetospheric plasma is brought about by inward diffusion of magnetized particles. Not only creating a density gradient toward the center of a dipole magnetic field, the inward diffusion also accelerates particles and provides a planetary radiation belt with high energy particles. Here, we report the first experimental observation of a “laboratory radiation belt” created in the ring trap 1 device. By spectroscopic measurement, we found an appreciable anisotropy in the ion temperature, proving the betatron acceleration mechanism which heats particles in the perpendicular direction with respect to the magnetic field when particles move inward. The energy balance model, including the heating mechanism, explains the observed ion temperature profile.

  16. Energetic Particles Dynamics in Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Ryou, A.S.; Sibeck, D. G.; Alexeev, I. I.

    2013-01-01

    We investigate the drift paths of energetic particles in Mercury's magnetosphere by tracing their motion through a model magnetic field. Test particle simulations solving the full Lorentz force show a quasi-trapped energetic particle population that gradient and curvature drift around the planet via "Shabansky" orbits, passing though high latitudes in the compressed dayside by equatorial latitudes on the nightside. Due to their large gyroradii, energetic H+ and Na+ ions will typically collide with the planet or the magnetopause and will not be able to complete a full drift orbit. These simulations provide direct comparison for recent spacecraft measurements from MESSENGER. Mercury's offset dipole results in an asymmetric loss cone and therefore an asymmetry in particle precipitation with more particles precipitating in the southern hemisphere. Since the planet lacks an atmosphere, precipitating particles will collide directly with the surface of the planet. The incident charged particles can kick up neutrals from the surface and have implications for the formation of the exosphere and weathering of the surface

  17. Magnetospheric dynamics and wave-particle interactions

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Russell, C. T.

    1976-01-01

    It has been demonstrated that two general classes of wave-particle interactions are of great importance for magnetospheric dynamics. Electromagnetic and electrostatic plasma instabilities give rise to relatively narrow-banded spontaneous emissions (e.g., ELF hiss, chorus, three-halves noise, ion cyclotron and ion-plasma-frequency turbulence) that can scatter trapped particles into the loss cone, leading to modified pitch-angle distributions, stable trapping limits, diffuse aurora, proton precipitation events, etc. The current-driven plasma instabilities give rise to impulsive ion acoustic or Buneman mode turbulence that provides very effective energy transfer (via the anomalous conductivity mechanism) at the bow shock and in regions where strong field-aligned currents are observed. We review these interactions and identify significant open questions that must be investigated during the IMS.

  18. Wave-particle interactions in the magnetosphere of Uranus

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.; Coroniti, F. V.; Scarf, F. L.

    1991-01-01

    The Voyager 2 encounter of Uranus has provided observations of plasma waves in and near the magnetosphere. These data, while the first from Uranus, will also be the only direct information on wave-particle interactions at this planet for many years to come. The observations include electrostatic waves upstream of the bow shock, turbulence in the shock Bernstein emissions and whistler mode waves in the magnetosphere, broadband electrostatic noise in the magnetotail, and a number of the other types of plasma waves which have yet to be clearly identified. Each of these types of waves exist in a plasma environment which both supports the growth of the waves and is modified by interactions with the waves. Wave-particle interactions provide the channels through which the waves can accelerate, scatter, or thermalize the plasmas. The most spectacular example in the case of Uranus is the extremely intense whistler mode activity in the inner magnetosphere which is the source of strong pitch angle diffusion. The resulting electron precipitation is sufficient to produce the auroral emissions observed by Voyager. The strong diffusion, however, presents the problem of supplying electrons in the range of 5 to 40 keV in order to support the losses to the atmosphere.

  19. Wave-particle interactions in the magnetosphere of Uranus

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.; Scarf, F. L.; Coroniti, F. V.

    1988-01-01

    The Voyager 2 encounter of Uranus has provided observations of plasma waves in and near the magnetosphere. These data, while the first from Uranus, will also be the only direct information on wave-particle interactions at this planet for many years to come. The observations include electrostatic waves upstream of the bow shock, turbulence in the shock, Bernstein emissions and whistler mode waves in the magnetosphere, broadband electrostatic noise in the magnetotail, and a number of the other types of plasma waves which have yet to be clearly identified. Each of these types of waves exist in a plasma environment which both supports the growth of the waves and is modified by interactions with the waves. Wave-particle interactions provide the channels through which the waves can accelerate, scatter, or thermalize the plasmas. The most spectacular example in the case of Uranus is the extremely intense whistler mode activity in the inner magnetosphere which is the source of strong pitch angle diffusion. The resulting electron precipitation is sufficient to produce the auroral emissions observed by Voyager. The strong diffusion, however, presents the problem of supplying electrons in the range of 5 to 40 keV in order to support the losses to the atmosphere.

  20. Wave-particle interactions in the magnetosphere of Uranus

    SciTech Connect

    Kurth, W.S.; Gurnett, D.A.; Scarf, F.L.; Coroniti, F.V.

    1988-07-01

    The Voyager 2 encounter of Uranus has provided observations of plasma waves in and near the magnetosphere. These data, while the first from Uranus, will also be the only direct information on wave-particle interactions at this planet for many years to come. The observations include electrostatic waves upstream of the bow shock, turbulence in the shock, Bernstein emissions and whistler mode waves in the magnetosphere, broadband electrostatic noise in the magnetotail, and a number of the other types of plasma waves which have yet to be clearly identified. Each of these types of waves exist in a plasma environment which both supports the growth of the waves and is modified by interactions with the waves. Wave-particle interactions provide the channels through which the waves can accelerate, scatter, or thermalize the plasmas. The most spectacular example in the case of Uranus is the extremely intense whistler mode activity in the inner magnetosphere which is the source of strong pitch angle diffusion. The resulting electron precipitation is sufficient to produce the auroral emissions observed by Voyager. The strong diffusion, however, presents the problem of supplying electrons in the range of 5 to 40 keV in order to support the losses to the atmosphere.

  1. Magnetospheric vortex formation: self-organized confinement of charged particles.

    PubMed

    Yoshida, Z; Saitoh, H; Morikawa, J; Yano, Y; Watanabe, S; Ogawa, Y

    2010-06-11

    A magnetospheric configuration gives rise to various peculiar plasma phenomena that pose conundrums to astrophysical studies; at the same time, innovative technologies may draw on the rich physics of magnetospheric plasmas. We have created a "laboratory magnetosphere" with a levitating superconducting ring magnet. Here we show that charged particles (electrons) self-organize a stable vortex, in which particles diffuse inward to steepen the density gradient. The rotating electron cloud is sustained for more than 300 s. Because of its simple geometry and self-organization, this system will have wide applications in confining single- and multispecies charged particles. PMID:20867249

  2. Possible leakage of energetic particles from the magnetosphere into the upstream region on June 7, 1985

    NASA Technical Reports Server (NTRS)

    Kudela, K.; Sibeck, D. G.; Belian, R. D.; Fischer, S.; Lutsenko, V.

    1990-01-01

    Prognoz 10 observed a series of energetic ion (E not less than 10 KeV) and electron (E not less than 30 KeV) bursts whilst upstream of the dusk bow shock from 2000-2200 UT on June 7, 1985. The particles streamed away from the bow shock along the interplanetary magnetic field (IMF) during periods when the IMF connected the spacecraft to the bow shock/magnetosphere. Both ions and electrons were observed when the IMF connected the spacecraft to the subsolar bow shock, but only ions were observed when the IMF connected the spacecraft to the dusk bow shock. Simultaneous ground and magnetospheric observations are presented which indicate the onset of geomagnetic activity and an increase in magnetospheric energetic particle flux levels just prior to the series of particle bursts observed by Prognoz 10 upstream of the bow shock. The combined observations are consistent with a magnetospheric source for these upstream particle events.

  3. OSCILLATION-DRIVEN MAGNETOSPHERIC ACTIVITY IN PULSARS

    SciTech Connect

    Lin, Meng-Xiang; Xu, Ren-Xin; Zhang, Bing E-mail: r.x.xu@pku.edu.cn

    2015-02-01

    We study the magnetospheric activity in the polar cap region of pulsars under stellar oscillations. The toroidal oscillation of the star propagates into the magnetosphere, which provides additional voltage due to unipolar induction, changes Goldreich-Julian charge density from the traditional value due to rotation, and hence influences particle acceleration. We present a general solution of the effect of oscillations within the framework of the inner vacuum gap model and consider three different inner gap modes controlled by curvature radiation, inverse Compton scattering, and two-photon annihilation, respectively. With different pulsar parameters and oscillation amplitudes, one of three modes would play a dominant role in defining the gap properties. When the amplitude of oscillation exceeds a critical value, mode changing occurs. Oscillations also lead to a change of the size of the polar cap. As applications, we show the inner gap properties under oscillations in both normal pulsars and anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs). We interpret the onset of radio emission after glitches/flares in AXPs/SGRs as due to oscillation-driven magnetic activities in these objects, within the framework of both the magnetar model and the solid quark star model. Within the magnetar model, radio activation may be caused by the enlargement of the effective polar cap angle and the radio emission beam due to oscillation, whereas within the solid quark star angle, it may be caused by activation of the pulsar inner gap from below the radio emission death line due to an oscillation-induced voltage enhancement. The model can also explain the glitch-induced radio profile change observed in PSR J1119–6127.

  4. Gyroresonant wave-particle interactions in a dynamic magnetosphere

    NASA Technical Reports Server (NTRS)

    Gail, W. B.; Inan, U. S.; Helliwell, R. A.; Carpenter, D. L.

    1990-01-01

    The response of the interaction mechanism to time-dependent perturbations in the magnetic field was examined using the global field compressions that occur during sudden commencements. This study was performed to assess the effect of nonequilibrium or dynamic magnetospheric processes on wave-particle interactions (WPI). It is shown that current theories of gyroresonant WPI, when modified to include a time-dependent magnetic field, can be used to predict the properties of WPI in a dynamic magnetospheric environment.

  5. Trajectory Traces of Charged Particles in the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Ejiri, M.

    1976-01-01

    The characteristic enhancements of ring current particles with energies of about 1 to 100 keV, associated with magnetospheric substorms, were observed by Explorer 45 around the plasmapause in the afternoon to midnight region, and showed the characteristic structure called a 'nose' in the proton spectrograms. The motion of these particles in the equatorial magnetosphere, under a recently proposed convection electric field and a dipole magnetic field is described. Approximate equations of a bounce period, a second adiabatic invariant, and a bounce-average azimuthal velocity are given with inaccuracies less than about 0.001 for all pitch angles. The complete set of flow patterns of 90 deg pitch angle particles is also presented by means of stagnation lines through which radial drifts and/or azimuthal drifts change their directions. The particle tracings in the magnetosphere give a basic concept to explain the observed nose characteristics.

  6. Energetic charged particles in Saturn's magnetosphere: Voyager 2 results

    SciTech Connect

    Vogt, R.E.; Chenette, D.L.; Cummings, A.C.; Garrard, T.L.; Stone, E.C.; Schardt, A.W.; Trainor, J.H.; Lal, N.; McDonald, F.B.

    1982-01-29

    Results from the cosmic-ray system on Voyager 2 in Saturn's magnetosphere are presented. During the inbound pass through the outer magnetosphere, the greater than or equal to 0.43-million-electron-volt proton flux was more intense, and both the proton and electron fluxes were more varible, than previously observed. These changes are attributed to the influence on the magnetosphere of variations in the solar wind conditions. Outbound, beyond 18 Saturn radii, impulsive bursts of 0.14- to > 1.0-million-electron-volt electrons were observed. In the inner magnetosphere, the charged particle absorption signatures of Mimas, Enceladus, and Tethys are used to constrain the possible tilt and offset of Saturn's internal magnetic dipole. At approx. 3 Saturn radii, a transient decrease was observed in the electron flux which was not due to Mimas. Characteristics of this decrease suggest the existence of additional material, perhaps another satellite, in the orbit of Mimas.

  7. The CUSP as a Source of Magnetospheric Particles

    NASA Technical Reports Server (NTRS)

    Fritz, Theodore A.; Chen, Jiasheng

    1999-01-01

    Observations made by the Polar satellite have shown that plasma of solar wind magnetosheath origin is rammed into the high altitude polar cusp creating a diamagnetic cavity of large dimensions. The Earth's dipole field can be excluded from this region in it turbulent manner with the magnitude of the field strength reaching close to zero nT at times. At such times energetic particles are produced in this region in intensities which exceed those measured in the trapping regions of the magnetosphere beyond L = 6.5. These particles can then flow back out of the cusp along field lines that form the magnetopause. A fraction of these particles can enter the magnetosphere along the magnetopause on the dusk and dawn flanks. Due to existing gradients in the geomagnetic field, cusp accelerated ions can enter the magnetosphere along the dawn flank and electrons along the dusk flank. For those particles entering near the geomagnetic equatorial plane with pitch angles close to ninety degrees they will drift along contours of constant magnetic field strength reaching deep into the nightside inner magnetosphere. From observations made by the Polar ATS-6, and ISEE satellites it is argued that this cusp source appears to be capable of providing energetic ions to the magnetosphere and possibly energetic electrons which form the source population of the Subsequent radial diffusion and formation of the radiation belts.

  8. Energetic particles in Saturn's middle magnetosphere

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Paranicas, C.; Roussos, E.

    2012-12-01

    The Cassini spacecraft has been exploring Saturn's magnetosphere in situ since 2004. In this study we use measurements from the MIMI/CHEMS and MIMI/LEMMS sensors in order to characterize and understand the distribution of energetic ions (10 keV to 1 MeV range) in Saturn's middle magnetosphere. CHEMS provides very good foreground to background ratios and can discriminate well among ion species. While the positions of the intensity maxima of Saturn's proton belts are located between the orbits of the icy moons and are independent of energy, the intensity maximum within the middle magnetosphere shifts with energy. We find indications that this shift is due to charge exchange in the neutral gas torus of Enceladus. Since the lower energies are easily lost, their maximum is farther out compared to the weakly interacting higher energies. However, the charge exchange lifetime at and outside of the intensity maximum is too long to be the only loss process, when other aspects of the MIMI data are considered. An important other process is thought to be radial diffusion caused by fluctuations of the magnetic and electric fields. This can cause that a moon can have an effect even several Saturn radii away from its orbit, a behavior that we indeed observed. However, we have also found that radial diffusion alone cannot account for the observations, even in regions where the neutral density is low.

  9. Low-energy particle population. [in Jupiter magnetosphere

    NASA Technical Reports Server (NTRS)

    Krimigis, S. M.; Roelof, E. C.

    1983-01-01

    A review is conducted of the measurements of the intensities, energy spectra, angular variations, and composition characteristics of the low-energy ion population in and around the Jovian magnetosphere, taking into account data obtained by both Voyager spacecraft. A description is provided of some novel analysis techniques which have been employed to generate density, pressure, composition, and plasma flow profiles in the magnetosphere. The obtained results are compared with data reported in connection with other investigations related to the spacecraft. Attention is given to the Low-Energy Charged Particle investigation, the Voyager 1 and 2 trajectories within 1000 Jupiter radii, and a hot plasma model of the Jovian magnetosphere. The measurement of hot multispecies convected plasmas using energetic particle detectors is also discussed.

  10. The problem of low energy particle measurements in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Whipple, E. C., Jr.

    1978-01-01

    The accurate measurement of low energy (less than 100 eV) particle properties in the magnetosphere has been difficult, partly because of the low density of such particles, but more particularly because of spacecraft interference effects. Some early examples of how these phenomena have affected particle measurements on an OGO spacecraft are presented. Data obtained with the UCSD particle detectors on ATS-6 are then presented showing how some of these difficulties have been partially overcome. Future measurements of low energy particles in the magnetosphere can be improved by: (1) improving the low energy resolution of detectors; (2) building electrostatically clean spacecraft; (3) controlling spacecraft potential; and (4) using auxiliary measurements, particularly wave data.

  11. Pioneer 11 observations of energetic particles in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Van Allen, J. A.; Randall, B. A.; Baker, D. N.; Goertz, C. K.; Sentman, D. D.; Thomsen, M. F.; Flindt, H. R.

    1975-01-01

    A preliminary report is presented of energetic electrons and protons observed with the University of Iowa instrument on Pioneer 11. A graph shows absolute, spin-averaged unidirectional intensities of electrons and protons as a function of time during traversal of the central magnetosphere. Another graph shows the effects of the Jovian satellites Io and Amalthea on particle intensities. It is pointed out that a full analysis of satellite effects is the most promising technique for understanding the physical dynamics of the magnetosphere of Jupiter.

  12. Energetic particles in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Trainor, J. H.; Mcdonald, F. B.; Teegarden, B. J.; Webber, W. R.; Roelof, E. C.

    1974-01-01

    A detailed account of the Pioneer 10 encounter with Jupiter is presented. Flux time histories of electrons and protons are given over a wide energy band. Proton and electron energy spectra are given at various Jovicentric distances. Proton spectra are shown to transform from a power law with indices in the 3-4.2 range to more nearly exponential forms in the inner regions. Extensive data are presented on the angular distributions of protons and electrons at various locations in the Jovicentric magnetosphere. In addition, a harmonic analysis of 1-2 MeV proton angular distributions was performed. Alpha/proton ratios are given as a function of Jovian radius and are compared to the earth and solar wind values.

  13. Energetic particles of the outer regions of planetary magnetospheres

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Goldstein, B. E.; Bratenahl, A.

    1976-01-01

    High energy particles, with energies above those attainable by adiabatic or steady-state electric field acceleration, have been observed in and around the outer regions of planetary magnetospheres. Acceleration by large amplitude sporadic cross-tail electric fields over an order of magnitude greater than steady-state convection fields is proposed as a source of these particles. It is suggested that such explosive electric fields will occur intermittently in the vicinity of the tail neutral line in the expansive phase of substorms. Laboratory and satellite evidence are used to estimate this electric potential for substorms at earth; values of 500 kilovolts to 2 megavolts are calculated, in agreement with particle observations. It is further suggested that these particles, which have been accelerated in the night side magnetosphere, drift to the dayside on closed field lines, and under certain interplanetary conditions can escape to regions upstream of the bow shock.

  14. Energetic helium particles trapped in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Chen, Jiasheng; Guzik, T. Gregory; Sang, Yeming; Wefel, John P.; Cooper, John F.

    1994-01-01

    High energy (approximately 40-100 MeV/nucleon) geomagnetically trapped helium nuclei have been measured, for the first time, by the ONR-604 instrument during the 1990/1991 Combined Release and Radiation Effects Satellite (CRRES) mission. The helium events observed at L less than 2.3 have a pitch angle distribution peaking perpendicular to the local magnetic field and are contained in peaks located at L = 1.2 and 1.9. The events in each peak can be characterized by power law energy spectra with indices of 10.0 +/- 0.7 for L = 1.9-2.3 and 6.8 +/- 1.0 for L = 1.15-1.3, before the large storm of 24 March 1991. CRRES was active during solar maximum when the anomalous component is excluded from the inner heliosphere, making it unlikely that the observed events derived from the anomalous component. The trapped helium counting rates decrease gradually with time indicating that these high energy ions were not injected by flares during the 1990/91 mission. Flare injection prior to mid-1990 may account for the highest energy particles, while solar wind injection during magnetic storms and subsequent acceleration could account for the helium at lower energies.

  15. Dynamics of energetic particles and neutrals in Saturn's variable magnetosphere: results from the MIMI investigation

    NASA Astrophysics Data System (ADS)

    Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.; Livi, S.; Roelof, E. C.; Dandouras, J.; Mauk, B. H.; Brandt, P. C.; Paranicas, C. P.; Saur, J.; Armstrong, T. P.; Bolton, S.; Cheng, A. F.; Gloeckler, G.; Hill, M. E.; Hsieh, K. C.; Ip, W. H.; Lagg, A.; Lanzerotti, L. J.; McEntire, R. W.; Williams, D. J.

    2005-08-01

    The Magnetospheric IMaging Instrument (MIMI) comprises three sensors: the Ion and Neutral Camera (INCA) provides images using energetic neutral atoms (ENA) and ions; the Charge-Energy-Mass-Spectrometer (CHEMS) determines the mass and charge state of ions; and the Low Energy Magnetospheric Measurement System (LEMMS) measures ion and electron distributions using a dual field-of-view telescope (Krimigis et al, Space Sci Rev,114, 2333-329, 2004). Measurements by MIMI after Saturn orbit insertion on 1 July 2004 have elucidated several new features of the planet's magnetosphere. These include: (1) A dynamical magnetosphere with an11-hour periodicity. (2) The first remotely-sensed radiation belt inside Saturn's D-ring. (3) Abundant water products in the magnetospheric plasma > or = 10 kev/charge, but little nitrogen (N+/O+<0.05); neutral gas is found to be a major mechanism for particle loss. (4) Injections of plasma in the ˜4-11Rs and also >20Rs corotate with the planet and can last for several days. (5) Activity (possibly analogous to Earth's substorms) occurs in Saturn's magnetotail in the 20-40 Rs region during large magnetospheric disturbances; this has not been observed during quiet times. (6) Field-aligned electron beams occur in the dawn to early morning sector as close as ˜10 Rs, and map to latitudes of observed Saturn aurora. (7) A gas cloud around Titan with dimensions > 1 Rs, with strong high ( 3200 km) altitude ENA emissions forms a continuous, asymmetric ``halo." (8) Titan's emission is centered on moon--hot plasma interaction with the exosphere; changing intensity depends on variable (x10-100) ion population and magnetic field orientation about Titan. (9) Upstream ion events have been measured to large (<50 to > 800 Rs) distances; several are enriched in oxygen ions, suggesting a magnetospheric origin. The observations will be presented and discussed in the context of current models of Saturn's magnetosphere.

  16. Particle Energization During Magnetic Storms with Steady Magnetospheric Convection

    NASA Astrophysics Data System (ADS)

    Kissinger, J.; Kepko, L.; Baker, D. N.; Kanekal, S. G.; Li, W.; McPherron, R. L.; Angelopoulos, V.

    2013-12-01

    Relativistic electrons pose a space weather hazard to satellites in the radiation belts. Although about half of all geomagnetic storms result in relativistic electron flux enhancements, other storms decrease relativistic electron flux, even under similar solar wind drivers. Radiation belt fluxes depend on a complex balance between transport, loss, and acceleration. A critically important aspect of radiation belt enhancements is the role of the 'seed' population--plasma sheet particles heated and transported Earthward by magnetotail processes--which can become accelerated by wave-particle interactions with chorus waves. While the effect of substorms on seed electron injections has received considerable focus, in this study we explore how quasi-steady convection during steady magnetospheric convection (SMC) events affects the transport and energization of electrons. SMC events are long-duration intervals of enhanced convection without any substorm expansions, and are an important mechanism in coupling magnetotail plasma populations to the inner magnetosphere. We detail the behavior of the seed electron population for stormtime SMC events using the Van Allen Probes in the outer radiation belt and THEMIS in the plasma sheet and inner magnetosphere. Together, the two missions provide the ability to track particle transport and energization from the plasma sheet into the radiation belts. We present SMC events with Van Allen Probes/THEMIS conjunctions and compare plasma sheet fast flows/enhanced transport to radiation belt seed electron enhancements. Finally we utilize statistical analyses to quantify the relative importance of SMC events on radiation belt electron acceleration in comparison to isolated substorms.

  17. Active experiments, magnetospheric modification, and a naturally occurring analogue

    NASA Technical Reports Server (NTRS)

    Kivelson, M. G.; Russell, C. T.

    1973-01-01

    Recently, a scheme has been proposed which would modify the magnetosphere by injecting plasma near the equator beyond the plasmapause and initiating wave-particle instabilities. The expected effects have been examined theoretically. Injection of plasma into this region is also a naturally occurring phenomenon produced by the cross-tail electric fields which are associated with geomagnetic activity. For further investigation of magnetospheric instabilities, the advantages of examining artificially injected plasma (control of time and location of injection and of the volume of plasma injected) contrast with the advantages of studying natural enhancements (no extra payload, frequent occurrence). Thus, the two types of experiments are complementary. In preliminary studies of natural plasma enhancements both ULF and ELF emissions have been observed. The ELF noise is consistent with generation by the electron cyclotron instability.

  18. A magnetospheric critical velocity experiment - Particle results

    NASA Technical Reports Server (NTRS)

    Torbert, R. B.; Newell, P. T.

    1986-01-01

    In March of 1983, a barium injection sounding rocket experiment (The Star of Lima) was conducted to investigate Alfven's critical ionization velocity (CIV) hypothesis in space. Included in the instrumented payload was a particle detection experiment consisting of five retarding potential analyzers. Despite conditions that appeared to be optimal for the critical velocity effect, the particle data, in agreement with optical observations, indicates that a fractional ionization of only approximately .0005 was observed, indicating that the conditions required for the effect to occur are still not well understood. However many of the required phenomena associated with the CIV effect were observed; in particular a superthermal electron population was formed at the expense of ion drift kinetic energy in the presence of intense electrostatic waves near the lower hybrid frequency. The amount of ionization produced is plausibly consistent with the observed electron flux, but could also be accounted for by residual solar UV at the injection point. It is shown based on the data set that one obvious explanation for the low ionization efficiency, namely that the ionizing superthermal electrons may rapidly escape along field lines, can be ruled out.

  19. Low-Energy Hot Plasma and Particles in Saturn's Magnetosphere.

    PubMed

    Krimigis, S M; Armstrong, T P; Axford, W I; Bostrom, C O; Gloeckler, G; Keath, E P; Lanzerotti, L J; Carbary, J F; Hamilton, D C; Roelof, E C

    1982-01-29

    The low-energy charged particle instrument on Voyager 2 measured low-energy electrons and ions (energies greater, similar 22 and greater, similar 28 kiloelectron volts, respectively) in Saturn's magnetosphere. The magnetosphere structure and particle population were modified from those observed during the Voyager 1 encounter in November 1980 but in a manner consistent with the same global morphology. Major results include the following. (i) A region containing an extremely hot ( approximately 30 to 50 kiloelectron volts) plasma was identified and extends from the orbit of Tethys outward past the orbit of Rhea. (ii) The low-energy ion mantle found by Voyager 1 to extend approximately 7 Saturn radii inside the dayside magnetosphere was again observed on Voyager 2, but it was considerably hotter ( approximately 30 kiloelectron volts), and there was an indication of a cooler ( < 20 kiloelectron volts) ion mantle on the nightside. (iii) At energies greater, similar 200 kiloelectron volts per nucleon, H(1), H(2), and H(3) (molecular hydrogen), helium, carbon, and oxygen are important constituents in the Saturnian magnetosphere. The presence of both H(2) and H(3) suggests that the Saturnian ionosphere feeds plasma into the magnetosphere, but relative abundances of the energetic helium, carbon, and oxygen ions are consistent with a solar wind origin. (iv) Low-energy ( approximately 22 to approximately 60 kiloelectron volts) electron flux enhancements observed between the L shells of Rhea and Tethys by Voyager 2 on the dayside were absent during the Voyager 1 encounter. (v) Persistent asymmetric pitch-angle distributions of electrons of 60 to 200 kiloelectron volts occur in the outer magnetosphere in conjunction with the hot ion plasma torus. (vi) The spacecraft passed within approximately 1.1 degrees in longitude of the Tethys flux tube outbound and observed it to be empty of energetic ions and electrons; the microsignature of Enceladus inbound was also observed. (vii

  20. Particle acceleration in the vacuum gaps in black hole magnetospheres

    NASA Astrophysics Data System (ADS)

    Ptitsyna, K.; Neronov, A.

    2016-08-01

    Aims: We consider particle acceleration in the vacuum gaps in magnetospheres of black holes powered by the Blandford-Znajek mechanism and embedded in the radiatively-inefficient accretion flow (RIAF) environment. In this situation, the gap height is limited by the onset of gamma-gamma pair production on the infrared photons originating in the RIAF. Methods: We numerically calculated the acceleration and propagation of charged particles by taking the detailed structure of the electric and magnetic fields in the gap and in the entire black hole magnetosphere into account, as well as the radiative energy losses and interactions of γ-rays produced by the propagated charged particles with the background radiation field of the RIAF. Results: We show that the presence of the vacuum gap has clear observational signatures. The spectra of emission from gaps embedded in a relatively high-luminosity RIAF are dominated by the inverse Compton emission with a sharp, super-exponential cut-off in the very-high-energy gamma-ray band. The cut-off energy is determined by the properties of the RIAF and is largely independent of the structure of magnetosphere and geometry of the gap. The spectra of the gap residing in low-luminosity RIAFs are dominated by synchrotron or curvature emission with the spectra extending into 1-100 GeV energy range. We also consider the effect of possible acceleration of protons in the gap and find that proton energies could reach the ultra-high-energy cosmic ray (UHECR) range only in extremely low-luminosity RIAFs.

  1. Modeling ionospheric electron precipitation due to wave particle scattering in the magnetosphere and the feedback effect on the magnetospheric dynamics

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Jordanova, V.; Ridley, A. J.; Albert, J.; Horne, R. B.; Jeffery, C. A.

    2015-12-01

    Electron precipitation down to the atmosphere caused by wave-particle scattering in the magnetosphere contribute significantly to the enhancement of auroral ionospheric conductivity. Global MHD models that are incapable of capturing kinetic physics in the inner magnetosphere usually adopt MHD parameters to specify the precipitation flux to estimate auroral conductivity, hence losing self-consistency in the global circulation of the magnetosphere-ionosphere system. In this study we improve the coupling structure in global models by connecting the physics-based (wave-particle scattering) electron precipitation with the ionospheric electrodynamics and investigate the feedback effect on the magnetospheric dynamics. We use BATS-R-US coupled with a kinetic ring current model RAM-SCB that solves pitch angle dependent particle distributions to study the global circulation dynamics during the Jan 25-26, 2013 storm event. Following tail injections, we found enhanced precipitation number and energy fluxes of tens of keV electrons being scattered into loss cone due to interactions with enhanced chorus and hiss waves in the magnetosphere. This results in a more profound auroral conductance and larger electric field imposing on the plasma transport in the magnetosphere. We also compared our results with previous methods in specifying the auroral conductance, such as empirical relation used in Ridley et al. (2004). It is found that our physics-based method develops a larger convection electric field in the near-Earth region and therefore leads to a more intense ring current.

  2. Charged Particles in Earth's Magnetosphere during Storm and Quiet time

    NASA Astrophysics Data System (ADS)

    Forster, D. R.; Grande, M.; Perry, C. H.; Davies, J. A.

    2009-04-01

    Ionic number density, taken by the Magnetospheric Ion Composition Spectrometer (MICS) instrument on the Combined Release and Radiation Effects Satellite (CRRES), are used to investigate the behaviour of singly charged Oxygen and Helium ions, and also Alpha Particles, while under both quiet and storm-time conditions during a Solar Maximum Period. Number density data are plotted against Invariant Latitude and Local time. The results of this investigation show clearly an enhancement of all species during periods of highly negative DST, and are in agreement with previous work (Grande et al, 1996, 2004).

  3. Particle Transport and Energization Associated with Disturbed Magnetospheric Events

    SciTech Connect

    C.Z. Cheng; J.R. Johnson; S. Zaharia

    1999-11-01

    Energetic particle flux enhancement events observed by satellites during strongly disturbed events in the magnetosphere (e.g., substorms, storm sudden commencements, etc.) are studied by considering interaction of particles with Earthward propagating electromagnetic pulses of westward electric field and consistent magnetic field of localized radial and azimuthal extent in a background magnetic field. The energetic particle flux enhancement is mainly due to the betatron acceleration process: particles are swept by the Earthward propagating electric field pulses via the EXB drift toward the Earth to higher magnetic field locations and are energized because of magnetic moment conservation. The most energized particles are those which stay in the pulse for the longest time and are swept the longest radial distance toward the Earth. Assuming a constant propagating velocity of the pulse we obtain analytical solutions of particle orbits. We examine substorm energetic particle injection by computing the particle flux and comparing with geosynchronous satellite observations. Our results show that for pulse parameters leading to consistency with observed flux values, the bulk of the injected particles arrive from distances less than 9 R(subscript E), which is closer to the Earth than the values obtained by the previous model and is also closer to the distances obtained by the injection boundary model.

  4. Particle Injection Through Reconnection In The Dayside Magnetosphere

    NASA Astrophysics Data System (ADS)

    Nishikawa, K. I.; Popescu, D.; Stenuit, H.; Fedorov, A.; Budnik, E.; Sauvaud, J. A.; Reme, H.; Lembege

    Present simulations based on a full 3-D particle electromagnetic code are performed in order to analyze the impact of a dawnward IMF field on the internal dynamics of the global 3-D magnetosphere. In the case that the northward IMF is switched gradually to dawnward, analysis of magnetic fields in the magnetopause confirms a signature of magnetic reconnection at both the dawnside and duskside. Arrival of dawnward IMF to the magnetopause creates a reconnection groove (where magnetic field is min- imum) which causes particle entry into the deep region of the magnetosphere via field lines that go near the magnetopause. This deep connection is more fully recognized tailward of Earth. The flank weak-field region (so called "sash") joins onto the plasma sheet and the plasma sheet to form a geometrical feature called the cross-tail S that structurally integrates the magnetopause and the tail interior. This structure might con- tribute to direct entry between the magnetosheath to plasma sheet in the tail. Local heating is also evidenced in the plasma sheet which may be related to magnetosheath plasma. Present results are supported by two points: (i) similar sashs have been also evidenced in previous MHD simulations (White et al., 1998), and (ii) observations by Interball show the weak magnetic field regions where particle injections with higher temperature were found.

  5. Energetic particle configuration in the magnetosphere of Saturn: Advances and open questions.

    NASA Astrophysics Data System (ADS)

    Sergis, N.

    2011-12-01

    The energetic particle population in Saturn's magnetosphere was initially sampled during the Pioneer 11 and Voyager 1 and 2 flybys in the early 1980s. It was, however, the far more sophisticated energetic particle suite, the Magnetospheric Imaging Instrument (MIMI) on the Cassini spacecraft that offered new insight of the energetic particles in Saturn's environment. Since July 2004, the three energetic particle detectors of MIMI, the Low Energy Magnetospheric Measurement System (LEMMS), the Charge Energy Mass Spectrometer (CHEMS) and the Ion and Neutral Camera (INCA), provide energetic ion directional intensities, ion and electron energy spectra and ion composition in a keV-to-MeV energy range. In particular, through detailed energetic neutral atoms (ENA) imaging, INCA resolved the perennial limitation of in situ data (spatial vs. temporal variability), offering an overview of large parts of the magnetosphere and capturing the ongoing dynamical activity (e.g. hot plasma injections), regardless of the spacecraft's position. The results obtained so far have clearly revealed that hot plasma plays a key role in several processes active in a wide range of spatial scales in the Saturnian magnetosphere, such as the formation of high energy trapped particle radiation belts in the inner magnetosphere and of a partial, rotating ring current in the middle and outer magnetosphere, the plasma energization in the midnight-to-dawn local time sector and the variability of the Saturnian auroral UV and radio emissions. The extended coverage provided by the numerous (over 150 as of August 2011) revolutions of Cassini has helped us construct a comprehensive (yet not complete) picture of the hot plasma distribution and composition in Saturn's magnetosphere. The most surprising characteristic was the direct observation that the energetic ion distribution is strongly asymmetric with local time, forming a broadened dayside plasma sheet which becomes thinner and more intense in the

  6. Particle acceleration by inductive electric fields in the Earth’s magnetosphere

    NASA Astrophysics Data System (ADS)

    Ilie, Raluca; Daldorff, Lars K. S.; Ganushkina, Natalia; Liemohn, Michael

    2015-04-01

    The terrestrial magnetosphere has the capability to rapidly accelerate charged particles up to very high energies over relatively short times and distances, leading to an increase in the near Earth currents. These energetic particles are injected from the magnetotail into the inner magnetosphere through two primary mechanisms. One transport method is the potential-driven convection. This occurs during periods of southward Interplanetary Magnetic Field (IMF), which allows part of the dawn-to-dusk solar wind electric field to effectively map down to the polar ionosphere. The second transport process, substorm activity, involves a sudden reconfiguration of the magnetic field and the creation of transient induced electric fields. The relative contribution of potential and inductive electric field driven convection resulting in the development of the storm-time ring current has remained an unresolved question in Geospace research.Since the energy of charged particles can be altered only by means of electric fields, knowledge of the relative contribution of potential versus inductive electric fields at intensifying the hot ion population in the inner magnetosphere is required. However, it is not possible to distinguish the two terms by only measuring the electric field. Therefore assessing the importance of induced electric field is possible by thorough examination of the time varying magnetic field and current systems using global modeling of the entire system.The induced electric field is calculated as a 3D integration over the entire magnetosphere domain. However, though computationally challenging, the full volume integration approach removes the need to trace independent field lines and lifts the assumption that the magnetic field lines can be treated as frozen in a stationary ionosphere.In this work, we quantitatively assess the relative contributions on potential and inductive electric fields at driving plasma sheet ions into the inner magnetosphere, as well as

  7. Erosion of Galilean satellite surfaces by Jovian magnetosphere particles

    NASA Technical Reports Server (NTRS)

    Johnson, R. E.; Lanzerotti, L. J.; Brown, W. L.; Armstrong, T. P.

    1981-01-01

    The effects on the surfaces of the Galilean satellites Europa, Ganymede and Callisto of impacts by particles of the Jupiter magnetosphere in which they are immersed are estimated. Differential ion fluxes measured by the Voyager low-energy magnetosphere particle analyzer as a function of ion energy were used to calculate ice erosion fluxes for the satellites under the assumption that each is 50% ice covered. Calculations were performed on the basis of laboratory data concerning the ice sputtering coefficients of protons and oxygen ions of various energies. A water erosion rate of greater than 10 to the 10th/sq cm per sec is obtained for Europa, which implies a total erosion over 1 billion years of an ice layer 100 m deep. Atmospheric column densities of the H2O molecules sputtered from the surface but not escaping the satellites are also calculated for the three satellites assuming a sputtered ion temperature of 2000 K, and are found to dominate those produced by sublimation. Finally, estimates are presented of the source and loss processes for an oxygen atmosphere around Ganymede created by sputtering or sublimation.

  8. Effects acting on energetic particles in Saturn's magnetosphere

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Roussos, E.; Paranicas, C.; Krupp, N.; Glassmeier, K.-H.

    2011-10-01

    Energetic charged particles can undergo a number of different effects in Saturn's magnetosphere. Some of these processes are well known, as the loss of ions due to charge exchange within the extended Neutral Torus. On average, these losses have to be compensated by source processes, but the mechanism and magnitude of them is poorly understood. Especially the origin of protons below 1 MeV within the radiation belts remains an open question. Since more than six years, the MIMI/LEMMS instrument onboard the Cassini spacecraft provides a wealth of knowledge about charged particles between several 10 keV and several 10 MeV. From this data, mission averaged proton profiles at constant adiabatic invariants are derived within the radiation belts (L < 5RS) and the middle magnetosphere (L > 5RS). We extended the radial diffusion equation by multiple source and loss terms in order to include all the relevant physics. Numerical solutions of this equation are able to reproduce the observed profiles. Due to the large number of effects, the equation includes parameters that are free as long as only a small range in energy and L is considered. Therefore, we aim to describe the whole range that is covered by LEMMS with the same set of parameters, which then can immediately be used to quantify the different effects they are representing.

  9. AB INITIO PULSAR MAGNETOSPHERE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS OF AXISYMMETRIC PULSARS

    SciTech Connect

    Philippov, Alexander A.; Spitkovsky, Anatoly

    2014-04-20

    We perform ''first-principles'' relativistic particle-in-cell simulations of aligned pulsar magnetosphere. We allow free escape of particles from the surface of a neutron star and continuously populate the magnetosphere with neutral pair plasma to imitate pair production. As pair plasma supply increases, we observe the transition from a charge-separated ''electrosphere'' solution with trapped plasma and no spin-down to a solution close to the ideal force-free magnetosphere with electromagnetically dominated pulsar wind. We calculate the magnetospheric structure, current distribution, and spin-down power of the neutron star. We also discuss particle acceleration in the equatorial current sheet.

  10. Charged Particle Environments in Earth's Magnetosphere and their Effects on Space System

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.

    2009-01-01

    This slide presentation reviews information on space radiation environments important to magnetospheric missions including trapped radiation, solar particle events, cosmic rays, and solar winds. It also includes information about ion penetration of the magnetosphere, galactic cosmic rays, solar particle environments, CRRES internal discharge monitor, surface charging and radiation effects.

  11. Assessment of inductive electric fields contribution to the overall particle energization in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Liemohn, M. W.; Daldorff, L. K. S.

    2015-12-01

    The terrestrial magnetosphere has the capability to rapidly accelerate charged particles up to very high energies over relatively short times and distances. These energetic particles are injected from the magnetotail into the inner magnetosphere through two primary mechanisms. One transport method is the potential-driven convection during periods of southward IMF, which allows part of the dawn-to-dusk solar wind electric field to effectively map down to the polar ionosphere. The second transport process, substorm activity, involves a sudden reconfiguration of the magnetic field and the creation of transient induced electric fields. However, it is not possible to distinguish the two terms by only measuring the electric field, which is typically just the potential field. Assessing the relative contribution of potential versus inductive electric fields at the energization of the hot ion population in the inner magnetosphere is only possible by thorough examination of the time varying magnetic field and current systems using global modeling of the entire system. We calculate the induced electric field via a 3D integration over the entire magnetosphere domain. This full volume integration approach removes the need to trace independent field lines and lifts the assumption that the magnetic field lines can be treated as frozen in a stationary ionosphere. We quantify the relative contributions of potential and inductive electric fields at driving plasma sheet ions into the inner magnetosphere during disturbed conditions. The consequence of these injections on the distortion of the near-Earth magnetic field and current systems have been rarely separated in order to determine their relative effectiveness from a global perspective.

  12. Martian induced magnetosphere variations with solar activity cycle

    NASA Astrophysics Data System (ADS)

    Fedorov, Andrey; Ronan, Modolo; Jarninen, Riku; Mazelle, Christian; Barabash, Stas

    2014-05-01

    During the last 6 years of ESA Mars Express mission we have accumulated plasma data taken inside and around the Martian induced magnetosphere corresponding to the increasing branch of solar activity. This data allows to make an enhanced study of the magnetosphere variations as a response of the solar activity level. Since Mars Express has no onboard magnetometer, we used the hybrid models of the Martian plasma environment to get a proper frame to make an adequate statistics of the magnetospheric response. In this paper we present a spatial distribution of the planetary plasma in the planetary wake as well as the ionsospheric escape as a function of the solar activity.

  13. Magnetospheric impulse response for many levels of geomagnetic activity

    NASA Technical Reports Server (NTRS)

    Bargatze, L. F.; Baker, D. N.; Hones, E. W., Jr.; Mcpherron, R. L.

    1985-01-01

    The temporal relationship between the solar wind and magnetospheric activity has been studied using 34 intervals of high time resolution IMP 8 solar wind data and the corresponding AL auroral activity index. The median values of the AL index for each interval were utilized to rank the intervals according to geomagnetic activity level. The linear prediction filtering technique was then applied to model magnetospheric response as measured by the AL index to the solar wind input function VB(s). The linear prediction filtering routine produces a filter of time-lagged response coefficients which estimates the most general linear relationship between the chosen input and output parameters of the magnetospheric system. It is found that the filters are composed of two response pulses speaking at time lags of 20 and 60 min. The amplitude of the 60-min pulse is the larger for moderate activity levels, while the 20-min pulse is the larger for strong activity levels. A possible interpretation is that the 20-min pulse represents magnetospheric activity driven directly by solar wind coupling and that the 60-min pulse represents magnetospheric activity driven by the release of energy previously stored in the magnetotail. If this interpretation is correct, the linear filtering results suggest that both the driven and the unloading models of magnetospheric response are important facets of a more comprehensive response model.

  14. Interplanetary Magnetic Field Control of the Entry of Solar Energetic Particles into the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Richard, R. L.; El-Alaoui, M.; Ashour-Abdalla, M.; Walker, R. J.

    2002-01-01

    We have investigated the entry of energetic ions of solar origin into the magnetosphere as a function of the interplanetary magnetic field orientation. We have modeled this entry by following high energy particles (protons and 3 He ions) ranging from 0.1 to 50 MeV in electric and magnetic fields from a global magnetohydrodynamic (MHD) model of the magnetosphere and its interaction with the solar wind. For the most part these particles entered the magnetosphere on or near open field lines except for some above 10 MeV that could enter directly by crossing field lines due to their large gyroradii. The MHD simulation was driven by a series of idealized solar wind and interplanetary magnetic field (IMF) conditions. It was found that the flux of particles in the magnetosphere and transport into the inner magnetosphere varied widely according to the IMF orientation for a constant upstream particle source, with the most efficient entry occurring under southward IMF conditions. The flux inside the magnetosphere could approach that in the solar wind implying that SEPs can contribute significantly to the magnetospheric energetic particle population during typical SEP events depending on the state of the magnetosphere.

  15. Cassini RPWS Measurement of Dust Particles in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Ye, S.; Gurnett, D. A.; Kurth, W. S.; Averkamp, T. F.; Kempf, S.; Hsu, S.; Sakai, S.; Morooka, M.; Wahlund, J.

    2013-12-01

    The Cassini Radio and Plasma Wave Science (RPWS) instrument can detect dust impacts when voltage pulses induced by the impact charges are observed in the wideband receiver. The size of the voltage pulse is proportional to the mass of the impacting dust particle. Based on the data collected during the E-ring crossings and Enceladus flybys, we show that the size distribution of the dust particles can be characterized as dn/dr ∝ rμ, where μ~-4. We compare the density of dust particles above a certain size threshold calculated from the impact rate with the Cosmic Dust Analyzer (CDA) High Rate Detector (HRD) data. When the monopole antenna is connected to the wideband receiver, the polarity of the dust impact signal is determined by the spacecraft potential and the location of the impact (on the spacecraft body or the antenna). Because the effective area of the antenna is relatively easy to estimate, we use the polarity ratio of the dust impacts to infer the effective area of the spacecraft body. RPWS onboard dust detection data is analyzed, from which we infer the sign of the spacecraft potential and the dust density within Saturn's magnetosphere. A new phenomenon called dust ringing has been found to reveal the electron density inside the Enceladus plume. The ringing frequencies, interpreted as the local plasma frequencies, are consistent with the values measured by other methods, i.e., Langmuir probe and upper hybrid resonance.

  16. Energetic particle drift motions in the outer dayside magnetosphere

    SciTech Connect

    Buck, R.M.

    1987-12-01

    Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B ''pockets'' in the geomagnetic field. Drift-shell branching caused by the minimum-B pockets is analyzed and interpreted in terms of an adiabatic shell branching and rejoining process. We examine the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field model. We find that shell branching annd rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. We determine the spatial extent of the stable trapping regions for the Choe-Beard model. We develop an adiabatic branching map methodology which completely identifies and describes the location of shell-branching points and the adiabatic trajectories of particles on branched shells, for any model field. We employ the map to develop synthetic pitch angle distributions near the dayside magnetopause by adiabatically transforming observed midnight distributions to the dayside. We find that outer dayside lines contain particles moving on branched and unbranched shells, giving rise to distinctive pitch angle distribution features. We find a good correlation between the pitch angles which mark the transition from branched to unbranched shells in the model, and the distinctive features of the OGO-5 distributions. In the morning sector, we observe large flux changes at critical pitch angles which correspond to B-pocket edges in the model. Measurements on inbound passes in the afternoon sector show first the adiabatic particle shadow, then the arrival of fluxes on rejoined shells, then fluxes on unbranced shells - in accord with model predictions. 204 refs., 138 figs., 2 tabs.

  17. Compressional acceleration of energetic particles during an enhancement of magnetospheric convection

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Qin, G.; Zhu, Y.

    2006-12-01

    When a gas is compressed, its temperature increases and particles in the gas are accelerated. Particle acceleration at collision shock waves acts on the same mechanism although the compression at the shock is very abrupt and particles need to depend on spatial diffusion to achieve energies more than 4 times their original energy. This is a first-order particle acceleration process and it is much more effective than the second-order energy diffusion in many space plasma environments. Based on the adiabatic theory of particle motion and the frozen-in-law of space plasma, we can write the rate of particle energy increase and particle pitch-angle change in terms of the divergence of plasma flow. It shows that particles are accelerated whenever the plasma with its embedded magnetic fields is compressed. If compression is in direction perpendicular to the magnetic field, particle pitch-angle gets larger and the particle distribution becomes more pancake-like. Inside the magnetosphere, a shock is unlikely, but plasma compression can still occur. This perhaps is driving particle acceleration during magnetic storm periods, but it should also occur during quiet times at lower rate. Using a model map of magnetospheric convection pattern, we found that the compression of magnetospheric plasma can play important roles in particle acceleration and trapping. It is a large-scale phenomenon. The strongest compressional acceleration occurs ~6-12 Re on the night-side plasma sheet. It has a correlation with the speed of external solar wind that drives the magnetospheric convection and the location of plasmapause that indicates the level of magnetospheric convection. In this paper, we are going to show how particle acceleration initiates and how the particle flux increases propagate through the magnetosphere during an enhancement of magnetospheric convection of magnetic storm. We will also discuss to role of particle diffusion in the acceleration process.

  18. Hot Plasma and Energetic Particles in Neptune's Magnetosphere.

    PubMed

    Krimigis, S M; Armstrong, T P; Axford, W I; Bostrom, C O; Cheng, A F; Gloeckler, G; Hamilton, D C; Keath, E P; Lanzerotti, L J; Mauk, B H; Van Allen, J A

    1989-12-15

    The low-energy charged particle (LECP) instrument on Voyager 2 measured within the magnetosphere of Neptune energetic electrons (22 kiloelectron volts /=0.5 MeV per nucleon) energies, using an array of solid-state detectors in various configurations. The results obtained so far may be summarized as follows: (i) A variety of intensity, spectral, and anisotropy features suggest that the satellite Triton is important in controlling the outer regions of the Neptunian magnetosphere. These features include the absence of higher energy (>/=150 keV) ions or electrons outside 14.4 R(N) (where R(N) = radius of Neptune), a relative peak in the spectral index of low-energy electrons at Triton's radial distance, and a change of the proton spectrum from a power law with gamma >/= 3.8 outside, to a hot Maxwellian (kT [unknown] 55 keV) inside the satellite's orbit. (ii) Intensities decrease sharply at all energies near the time of closest approach, the decreases being most extended in time at the highest energies, reminiscent of a spacecraft's traversal of Earth's polar regions at low altitudes; simultaneously, several spikes of spectrally soft electrons and protons were seen (power input approximately 5 x 10(-4) ergs cm(-2) s(-1)) suggestive of auroral processes at Neptune. (iii) Composition measurements revealed the presence of H, H(2), and He(4), with relative abundances of 1300:1:0.1, suggesting a Neptunian ionospheric source for the trapped particle population. (iv) Plasma pressures at E >/= 28 keV are maximum at the magnetic equator with beta approximately 0.2, suggestive of a relatively empty magnetosphere, similar to that of Uranus. (v) A potential signature of satellite 1989N1 was seen, both inbound and outbound; other possible signatures of the moons and rings are evident in the data but cannot be positively identified in the

  19. Ab Initio Pulsar Magnetosphere: Three-dimensional Particle-in-cell Simulations of Oblique Pulsars

    NASA Astrophysics Data System (ADS)

    Philippov, Alexander A.; Spitkovsky, Anatoly; Cerutti, Benoit

    2015-03-01

    We present “first-principles” relativistic particle-in-cell simulations of the oblique pulsar magnetosphere with pair formation. The magnetosphere starts to form with particles extracted from the surface of the neutron star. These particles are accelerated by surface electric fields and emit photons capable of producing electron-positron pairs. We inject secondary pairs at the locations of primary energetic particles whose energy exceeds the threshold for pair formation. We find solutions that are close to the ideal force-free magnetosphere with the Y-point and current sheet. Solutions with obliquities ≤40° do not show pair production in the open field line region because the local current density along the magnetic field is below the Goldreich-Julian value. The bulk outflow in these solutions is charge-separated, and pair formation happens in the current sheet and return current layer only. Solutions with higher inclinations show pair production in the open field line region, with high multiplicity of the bulk flow and the size of the pair-producing region increasing with inclination. We observe the spin-down of the star to be comparable to MHD model predictions. The magnetic dissipation in the current sheet ranges between 20% for the aligned rotator and 3% for the orthogonal rotator. Our results suggest that for low obliquity neutron stars with suppressed pair formation at the light cylinder, the presence of phenomena related to pair activity in the bulk of the polar region, e.g., radio emission, may crucially depend on the physics beyond our simplified model, such as the effects of curved spacetime or multipolar surface fields.

  20. Low Energy Particle Oscillations and Correlations with Hydromagnetic Waves in the Jovian Magnetosphere: Ulysses Measurements

    NASA Technical Reports Server (NTRS)

    Krupp, N.; Tsurutani, B. T.; Lanzerotti, L. J.; Maclennan, C. G.

    1996-01-01

    We report on measurements of energetic particle modulations observed by the HI-SCALE instrument aboard the Ulysses Spacecraft that were associated with the only hydromagnetic wave event measured inside the Jovian magnetosphere by the Ulysses magnetometer investigation.

  1. A Solar Cycle Dependence of Nonlinearity in Magnetospheric Activity

    SciTech Connect

    Johnson, Jay R; Wing, Simon

    2005-03-08

    The nonlinear dependencies inherent to the historical K(sub)p data stream (1932-2003) are examined using mutual information and cumulant based cost as discriminating statistics. The discriminating statistics are compared with surrogate data streams that are constructed using the corrected amplitude adjustment Fourier transform (CAAFT) method and capture the linear properties of the original K(sub)p data. Differences are regularly seen in the discriminating statistics a few years prior to solar minima, while no differences are apparent at the time of solar maximum. These results suggest that the dynamics of the magnetosphere tend to be more linear at solar maximum than at solar minimum. The strong nonlinear dependencies tend to peak on a timescale around 40-50 hours and are statistically significant up to one week. Because the solar wind driver variables, VB(sub)s and dynamical pressure exhibit a much shorter decorrelation time for nonlinearities, the results seem to indicate that the nonlinearity is related to internal magnetospheric dynamics. Moreover, the timescales for the nonlinearity seem to be on the same order as that for storm/ring current relaxation. We suggest that the strong solar wind driving that occurs around solar maximum dominates the magnetospheric dynamics suppressing the internal magnetospheric nonlinearity. On the other hand, in the descending phase of the solar cycle just prior to solar minimum, when magnetospheric activity is weaker, the dynamics exhibit a significant nonlinear internal magnetospheric response that may be related to increased solar wind speed.

  2. Prediction of Solar Energetic Particle Trapping in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Engel, M.; Larsen, B. A.

    2012-12-01

    Solar energetic particles (SEPs) are protons, electrons, and heavy ions emitted from the Sun with energies spanning tens of keV to GeV. They are episodic and associated with energetic events at the Sun such as coronal mass ejections. Importantly, they can be injected into and trapped by the Earth's magnetosphere, forming transient new, intense radiation belts in the L=3 to L=4 range. These belts can severely damage components of our space infrastructure and cause significant backgrounds in instruments on national security and scientific payloads. The main questions we address here are, what is the difference between an event which causes a new belt to form and one that doesn't? And is the formation of new belts predictable in any way? Using both POES and ACE data we examine the overall likelihood of an event becoming trapped and relate it to various parameters from the data. Here we discuss the trapping criteria used and the categorization of each event, along with the parameters that were compared and their significance. And finally we provide a probabilistic measure of the trapping likelihood of a given event, thus answering, at least in part, our questions.

  3. Soft Particle Spectrometer, Langmuir Probe, and Data Analysis for Aerospace Magnetospheric/Thermospheric Coupling Rocket Program

    NASA Technical Reports Server (NTRS)

    Sharber, J. R.; Frahm, R. A.; Scherrer, J. R.

    1997-01-01

    Under this grant two instruments, a soft particle spectrometer and a Langmuir probe, were refurbished and calibrated, and flown on three instrumented rocket payloads as part of the Magnetosphere/Thermosphere Coupling program. The flights took place at the Poker Flat Research Range on February 12, 1994 (T(sub o) = 1316:00 UT), February 2, 1995 (T(sub o) = 1527:20 UT), and November 27, 1995 (T(sub o) = 0807:24 UT). In this report the observations of the particle instrumentation flown on all three of the flights are described, and brief descriptions of relevant geophysical activity for each flight are provided. Calibrations of the particle instrumentation for all ARIA flights are also provided.

  4. Nonlinear longitudinal resonance interaction of energetic charged particles and VLF waves in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Tkalcevic, S.

    1982-01-01

    The longitudinal resonance of waves and energetic electrons in the Earth's magnetosphere, and the possible role this resonance may play in generating various magnetospheric phenomena are studied. The derivation of time-averaged nonlinear equations of motion for energetic particles longitudinally resonant with a whistler mode wave propagating with nonzero wave normal is considered. It is shown that the wave magnetic forces can be neglected at lower particle pitch angles, while they become equal to or larger than the wave electric forces for alpha 20 deg. The time-averaged equations of motion were used in test particle simulation which were done for a wide range of wave amplitudes, wave normals, particle pitch angles, particle parallel velocities, and in an inhomogeneous medium such as the magnetosphere. It was found that there are two classes of particles, trapped and untrapped, and that the scattering and energy exchange for those two groups exhibit significantly different behavior.

  5. A Statistical Study of Wave Activity in the Hermian Magnetosphere.

    NASA Astrophysics Data System (ADS)

    James, M. K.; Bunce, E. J.; Yeoman, T. K.; Imber, S. I.

    2015-10-01

    A statistical study of wave activity within the Hermian magnetosphere is undertaken using data obtained from the MESSENGER mission between March 2011 and March 2014. Wave activity is categorised by its predominant polarisation - allowing for the comparison between compressional wave events and those more Alfvénic in nature. The position of the spacecraft at the time of each spectrum is mapped both to the magnetic equatorial plane, and the planetary surface at Mercury in order to determine the location of each wave event within the magnetosphere.

  6. Solar cycle dynamics of solar, magnetospheric, and heliospheric particles, and long-term atmospheric coupling: SAMPLEX

    NASA Technical Reports Server (NTRS)

    Mason, G. M. (Principal Investigator); Hamilton, D. C.; Blake, J. B.; Mewaldt, R. A.; Stone, E. C.; Baker, D. N.; VonRosenvinge, T. T.; Callis, L. B.; Klecker, B.; Hovestadt, D.; Scholer, M.

    1996-01-01

    This report summarizes science analysis activities by the SAMPEX mission science team during the period during the period July 1, 1995 through July 1, 1996. Bibliographic entries for 1995 and 1996 to date (July 1996) are included. The SAMPEX science team was extremely active, with 20 articles published or submitted to refereed journals, 18 papers published in their entirety in Conference Proceedings, and 53 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings of anomalous cosmic rays, solar energetic particles, magnetospheric precipitating electrons, trapped H and He isotopes, and data analysis activities.

  7. A new magnetic pumping accelerator of charged particles in Jupiter's magnetosphere

    NASA Astrophysics Data System (ADS)

    Mu, J.-L.

    1993-07-01

    This paper proposes an acceleration mechanism to explain the observations of energetic particles in the inner magnetosphere of Jupiter. In the inner magnetosphere particles are convected towards and away from the Io plasma torus by the centrifugally driven interchange mode or by the longitudinal asymmetry of the magnetosphere and the Io plasma torus. They experience a varying (space-dependent in Jupiter's frame of reference) magnetic field and are subject to pitch-angle scattering by wave-particle interactions. Thus, an e-fold magnetic pumping acceleration is expected in the system. The calculations show that the accelerator can generate up to one MeV energy particles in about 10-15 times the characteristic convection time.

  8. Energetic charged particles in the magnetosphere of neptune.

    PubMed

    Stone, E C; Cummings, A C; Loooper, M D; Selesnick, R S; Lal, N; McDonald, F B; Trainor, J H; Chenette, D L

    1989-12-15

    The Voyager 2 cosmic ray system (CRS) measured significant fluxes of energetic [>/=1 megaelectron volt (MeV)] trapped electrons and protons in the magnetosphere of Neptune. The intensities are maximum near a magnetic L shell of 7, decreasing closer to the planet because of absorption by satellites and rings. In the region of the inner satellites of Neptune, the radiation belts have a complicated structure, which provides some constraints on the magnetic field geometry of the inner magnetosphere. Electron phase-space densities have a positive radial gradient, indicating that they diffuse inward from a source in the outer magnetosphere. Electron spectra from 1 to 5 MeV are generally well represented by power laws with indices near 6, which harden in the region of peak flux to power law indices of 4 to 5. Protons have significantly lower fluxes than electrons throughout the magnetosphere, with large anisotropies due to radial intensity gradients. The radiation belts resemble those of Uranus to the extent allowed by the different locations of the satellites, which limit the flux at each planet. PMID:17756005

  9. An eastward propagating compressional Pc 5 wave observed by AMPTE/CCE in the postmidnight sector. [Active Magnetospheric Particle Tracer Explorers

    NASA Technical Reports Server (NTRS)

    Takahashi, K.; Mcentire, R. W.; Zanetti, L. J.; Lopez, R. E.; Kistler, L. M.

    1987-01-01

    This paper presents a detailed analysis of a compressional Pc 5 wave observed in the postmidnight sector on July 21, 1986, using data from the magnetometer, the charge-energy-mass spectrometer, and the medium-energy particle analyzer aboard the AMPTE/Charge Composition Explorer (CCE) spacecraft. The Pc 5 wave exhibited harmonically related transverse and compressional magnetic oscillations, modulation of the flux of medium energy protons, and a large azimuthal wave number, i.e., properties that are similar to those of compressional Pc5 waves observed previously at geostationary orbit. The unique observations recorded by the AMPTE/CCE included the occurrence of the wave in the postmidnight sector, its sunward propagation with respect to the spacecraft, and the left-handed polarization of the perturbed magnetic field. In spite of the morphological uniqueness observed, the excitation of the July 21 event is considered to be due to the same type of instability as operates at geostationary orbit.

  10. Modeling of ion dynamics in the inner geospace during enhanced magnetospheric activity

    NASA Astrophysics Data System (ADS)

    Tsironis, C.; Anastasiadis, A.; Katsavrias, C.; Daglis, I. A.

    2016-02-01

    We investigate the effect of magnetic disturbances on the ring current buildup and the dynamics of the current systems in the inner geospace by means of numerical simulations of ion orbits during enhanced magnetospheric activity. For this purpose, we developed a particle-tracing model that solves for the ion motion in a dynamic geomagnetic field and an electric field due to convection, corotation and Faraday induction and which mimics reconfigurations typical to such events. The kinematic data of the test particles is used for analyzing the dependence of the system on the initial conditions, as well as for mapping the different ion species to the magnetospheric currents. Furthermore, an estimation of Dst is given in terms of the ensemble-averaged ring and tail currents. The presented model may serve as a tool in a Sun-to-Earth modeling chain of major solar eruptions, providing an estimation of the inner geospace response.

  11. Understanding of particle acceleration and loss in Jupiter's magnetosphere from Juno mission

    NASA Astrophysics Data System (ADS)

    Bolton, Scott

    2016-07-01

    Juno is the first Jupiter polar mission. Juno science goals include the study of Jupiter's origin, interior structure, deep atmosphere, aurora and magnetosphere. The payload consists of a set of microwave antennas for deep sounding, magnetometers, gravity radio science, low and high energy charged particle detectors, electric and magnetic field radio and plasma wave experiment, ultraviolet imaging spectrograph, infrared imager and a visible camera. Juno's extensive suite of fields and particle experiments along with the UV and IR imagers will provide the first detailed investigation of Jupiter's polar magnetosphere. The set of six microwave radiometers on Juno provide an unprecedented view of Jupiter's synchrotron emission from inside Jupiter's powerful radiation belts. The Juno mission design, science goals, and measurements related to the magnetosphere and radiation belts of Jupiter will be presented.

  12. Relationship Between Dipolarizations and Energetic Particle Injections in Earth's Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Hartline, C. J.; Gkioulidou, M.; Ohtani, S.; Ukhorskiy, A. Y.; Takahashi, K.; Mitchell, D. G.; Lanzerotti, L. J.

    2015-12-01

    Energetic particle injections in Earth's magnetotail are associated with sharp dipolarizations of magnetic field, which are often referred to as dipolarization fronts. Particle experiments of the Van Allen Probes missions observed multiple energetic particle injection signatures inside the geosynchronous orbit, which resemble particle injections in the magnetotail. It is not evident, however, whether these events are attributed to the magnetic field dipolarizations considering how strong the background magnetic field is. Similar signatures could be attributed to the boundary crossings, i.e., when the spacecraft are crossing from the inner magnetosphere into the plasma sheet. To investigate the nature of the injection-like events observed by Van Allen Probes in the inner magnetosphere we first identify them with the use of the energetic particle measurements from the RBSPICE experiment. We then explore their relationship to the magnetic field dipolarizations and boundary crossings by examining the magnetic field data from the EMFISIS instrument.

  13. The GEMSIS-Magnetosphere project: New models of the inner magnetosphere to investigate high-energy particle variation and the ERG science center

    NASA Astrophysics Data System (ADS)

    Seki, K.; Miyoshi, Y.; Amano, T.; Saito, S.; Miyashita, Y.; Matsumoto, Y.; Umeda, T.; Ebihara, Y.

    2010-12-01

    Geospace storms are the largest electromagnetic disturbance in near-Earth space and facilitate extensive particle acceleration in the inner magnetosphere, which causes development of the ring current and a drastic increase of relativistic electrons in the radiation belt. GEMSIS (Geospace Environment Modeling System for Integrated Studies) of STEL, Nagoya University, is the observation-based modeling project for understanding energy and mass transportation from the Sun to the Earth in the geospace environment. Aiming at understanding the dynamics of the inner magnetosphere during the geospace storms, the GEMSIS-Magnetosphere working team has addressed the development of new physics-based models for the global dynamics of the ring current (GEMSIS-RC model) and radiation belt (GEMSIS-RB model). The GEMSIS-RC model is a self-consistent and kinetic numerical simulation code solving the five-dimensional collisionless drift-kinetic equation for the ring-current ions in the inner-magnetosphere coupled with Maxwell equations. It is demonstrated that the propagation of magnetohydrodynamic waves can successfully be described by the present model. It is also found that the self-consistent coupling could affect the transport of energetic particles especially at low energies as well as the intensity and spatial distribution of field-aligned currents. Our approach is unique in the sense that it includes MHD wave modes as well as deformation of magnetic field configuration due to the ring current self-consistently. To understand the dynamics of the radiation belt, we have developed the GEMSIS-RB model that calculates relativistic charged particle trajectories in the magnetosphere. By applying time-varying magnetic field data calculated from the Tsyganenko model and using observed solar wind data and the Dst index, we first examined the drift loss of relativistic electrons by magnetopause shadowing (MPS). Initial results show a split in the outer radiation belt after the

  14. Advances in Inner Magnetosphere Passive and Active Wave Research

    NASA Technical Reports Server (NTRS)

    Green, James L.; Fung, Shing F.

    2004-01-01

    This review identifies a number of the principal research advancements that have occurred over the last five years in the study of electromagnetic (EM) waves in the Earth's inner magnetosphere. The observations used in this study are from the plasma wave instruments and radio sounders on Cluster, IMAGE, Geotail, Wind, Polar, Interball, and others. The data from passive plasma wave instruments have led to a number of advances such as: determining the origin and importance of whistler mode waves in the plasmasphere, discovery of the source of kilometric continuum radiation, mapping AKR source regions with "pinpoint" accuracy, and correlating the AKR source location with dipole tilt angle. Active magnetospheric wave experiments have shown that long range ducted and direct echoes can be used to obtain the density distribution of electrons in the polar cap and along plasmaspheric field lines, providing key information on plasmaspheric filling rates and polar cap outflows.

  15. Effects of Finite Element Resolution in the Simulation of Magnetospheric Particle Motion

    NASA Technical Reports Server (NTRS)

    Hansen, Richard

    2006-01-01

    This document describes research done in conjunction with a degree program. The purpose of the research was to compare particle trajectories in a specified set of global electric and magnetic fields; to study the effect of mesh spacing, resulting in an evaluation of adequate spacing resolution; and to study time-dependent fields in the context of substorm dipolarizations of the magnetospheric tail.

  16. Throat aurora: The ionospheric signature of magnetosheath particles penetrating into the magnetosphere

    NASA Astrophysics Data System (ADS)

    Han, D.-S.; Nishimura, Y.; Lyons, L. R.; Hu, H.-Q.; Yang, H.-G.

    2016-03-01

    Throat aurora is suggested to be generated during magnetospheric cold plasma flowing into the magnetopause reconnection site and to be the ionospheric signature of the newly opened flux from reconnection. By examining simultaneous low-altitude satellites and ground observations, we confirm that the throat auroras are associated with low-energy electron and ion precipitation of magnetosheath type and thus provide the first evidence that they occur along open magnetic field lines. Additionally, the observations have important possible implications: (1) solar wind particles can penetrate deep into the magnetosphere and may make significant contributions to the low-energy plasmas often observed in the dayside outer magnetosphere and (2) localized shapes of the magnetopause and the ionospheric open-closed field line boundary may be substantially changed, during generation of the throat aurora.

  17. Particle energization in the inner, nonazimuthally symmetric magnetospheres of neutron stars

    NASA Technical Reports Server (NTRS)

    Borovsky, J. E.; Goertz, C. K.; Joyce, G.

    1980-01-01

    The energization process of magnetic pumping, a combination of time dependent magnetic mirror fields with pitch-angle scattering, is applied to trapped charged particles drifting in corotating, azimuthally nonsymmetric neutron star magnetospheres. When particle energization is balanced by synchrotron radiation loss, it is found that protons, rather than electrons, reach considerable kinetic energies and radiate, in the X-ray regime, at rates up to the 10 to the 6th power MeV/proton/sec.

  18. Modeling magnetospheric energetic particle escape across Earth's magnetopause as observed by the MMS mission

    NASA Astrophysics Data System (ADS)

    Mauk, Barry H.; Cohen, Ian J.; Westlake, Joseph H.; Anderson, Brian J.

    2016-05-01

    A longstanding puzzle is that the escape of magnetospheric energetic particles (greater than tens of keV) across Earth's magnetopause into the magnetosheath is common irrespective of conditions thought to engender magnetic reconnection and boundary normal magnetic fields. Multiple causes for escape have been invoked, including interactions with strong gradients, wave scattering, boundary dynamics, and boundary normal fields. Here we tackle only part of the problem by developing a relatively simple kinetic model including critical features not utilized in previous models. We find that particles can often completely escape without invoking waves or unmodeled magnetosheath structures for both northwardly and southwardly magnetosheath fields. Because multiple means of escape are found to be available, the particles are hard to completely contain, consistent with observations. The model also predicts specific pitch angle evolution signatures that uniquely identify boundary normal field-enabled escape, now reported in a companion paper as observed by the Magnetospheric Multiscale (MMS) mission.

  19. Charged particle motions in the distended magnetospheres of Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Birmingham, T. J.

    1982-01-01

    Charged particle motion in the guiding center approximation is analyzed for models of the Jovian and Saturnian magnetospheric magnetic fields based on Voyager magnetometer observations. Field lines are traced and exhibit the distention which arises from azimuthally circulating magnetospheric currents. The spatial dependencies of the guiding center bounce period and azimuthal drift rate are investigated for the model fields. Non-dipolar effects in the gradient-curvature drift rate are most important at the equator and affect particles with all mirror latitudes. The effect is a factor of 10-15 for Jupiter with its strong magnetodisc current and 1-2 for Saturn with its more moderate ring current. Limits of adiabaticity, where particle gyroradii become comparable with magnetic scale lengths, are discussed and are shown to occur at quite modest kinetic energies for protons and heavier ions.

  20. Acceleration and injection of particles inside the magnetosphere changes during duskward IMF By: statistical approach

    NASA Astrophysics Data System (ADS)

    Yan, X.; Cai, D.; Lembege, B.; Nishikawa, K.

    2005-12-01

    The change of the interplanetary magnetic field (IMF) direction from northward to duskward has an important impact on the inner magnetosphere as analyzed in a recent paper [Yan et al, GRL, to appear] . This impact is analyzed with the help of a new parallel version of the global three-dimensional full particle simulation. As the newly duskward-oriented IMF interacts with the magnetosphere, bands of weak magnetic field (sash) move to the equator (within opposite quadrants), reach lower latitude and merge into each other to form characteristic ``Crosstail-S" structures within the neutral sheet of the magnetotail. The analysis of particle fluxes shows that ``sashs" and ``Crosstail-S" act as magnetic groove to facilitate the entry and injection of magnetosheath particles into the inner magnetosphere. Injected particles are accelerated after the IMF changes its direction from northward to duskward. Characteristic times associated to the changes of the particle dynamics are estimated from the simulations. These informations are thought to be helpful as pre-signatures announcing the triggering of magnetic substorms.

  1. Modeling the winds and magnetospheres of active OB stars

    NASA Astrophysics Data System (ADS)

    Townsend, Richard H. D.

    2011-07-01

    After briefly reviewing the theory behind the radiative line-driven winds of OB stars, I examine the processes that can generate structure in them; these include both intrinsic instabilities, and surface perturbations such as pulsation and rotation. I then delve into wind channeling and confinement by magnetic fields as a mechanism for forming longer-lived circumstellar structures. With a narrative that largely follows the historical progression of the field, I introduce the key insights and results that link the first detection of a magnetosphere, over three decades ago, to the recent direct measurement of magnetic braking in a number of active OB stars.

  2. Modeling the entry and trapping of solar energetic particles in the magnetosphere during the November 24-25, 2001 storm

    NASA Astrophysics Data System (ADS)

    Richard, R. L.; El-Alaoui, M.; Ashour-Abdalla, M.; Walker, R. J.

    2009-04-01

    We have modeled the entry of solar energetic particles (SEPs) into the magnetosphere during the November 24-25, 2001 magnetic storm and the trapping of particles in the inner magnetosphere. The study used the technique of following many test particles, protons with energies greater than about 100 keV, in the electric and magnetic fields from a global magnetohydrodynamic (MHD) simulation of the magnetosphere during this storm. SEP protons formed a quasi-trapped and trapped population near and within geosynchronous orbit. Preliminary data comparisons show that the simulation does a reasonably good job of predicting the differential flux measured by geosynchronous spacecraft. Particle trapping took place mainly as a result of particles becoming non-adiabatic and crossing onto closed field lines. Particle flux in the inner magnetosphere increased dramatically as an interplanetary shock impacted and compressed the magnetosphere near 0600 UT, but long term trapping (hours) did not become widespread until about an hour later, during a further compression of the magnetosphere. Trapped and quasi-trapped particles were lost during the simulation by motion through the magnetopause and by precipitation, primarily the former. This caused the particle population near and within geosynchronous orbit to gradually decrease later on during the latter part of the interval.

  3. Global electric field determination in the Earth's outer magnetosphere using energetic charged particles

    NASA Technical Reports Server (NTRS)

    Eastman, Timothy E.; Sheldon, R.; Hamilton, D.

    1995-01-01

    Although many properties of the Earth's magnetosphere have been measured and quantified in the past 30 years since it was discovered, one fundamental measurement (for zeroth order MHD equilibrium) has been made infrequently and with poor spatial coverage - the global electric field. This oversight is due in part to the neglect of theorists. However, there is renewed interest in the convection electric field because it is now realized to be central to many magnetospheric processes, including the global MHD equilibrium, reconnection rates, Region 2 Birkeland currents, magnetosphere ionosphere coupling, ring current and radiation belt transport, substorm injections, and several acceleration mechanisms. Unfortunately the standard experimental methods have not been able to synthesize a global field (excepting the pioneering work of McIlwain's geostationary models) and we are left with an overly simplistic theoretical field, the Volland-Stern electric field model. Single point measurements of the plasmapause were used to infer the appropriate amplitudes of this model, parameterized by K(sub p). Although this result was never intended to be the definitive electric field model, it has gone nearly unchanged for 20 years. The analysis of current data sets requires a great deal more accuracy than can be provided by the Volland-Stern model. The variability of electric field shielding has not been properly addressed although effects of penetrating magnetospheric electric fields has been seen in mid-and low-latitude ionospheric data sets. The growing interest in substorm dynamics also requires a much better assessment of the electric fields responsible for particle injections. Thus we proposed and developed algorithms for extracting electric fields from particle data taken in the Earth's magnetosphere. As a test of the effectiveness of these new techniques, we analyzed data taken by the AMPTE/CCE spacecraft in equatorial orbit from 1984 to 1989.

  4. The Fly's Eye Energetic Particle Spectrometer (FEEPS) Sensors for the Magnetospheric Multiscale (MMS) Mission

    NASA Astrophysics Data System (ADS)

    Blake, J. B.; Mauk, B. H.; Baker, D. N.; Carranza, P.; Clemmons, J. H.; Craft, J.; Crain, W. R.; Crew, A.; Dotan, Y.; Fennell, J. F.; Friedel, R. H.; Friesen, L. M.; Fuentes, F.; Galvan, R.; Ibscher, C.; Jaynes, A.; Katz, N.; Lalic, M.; Lin, A. Y.; Mabry, D. M.; Nguyen, T.; Pancratz, C.; Redding, M.; Reeves, G. D.; Smith, S.; Spence, H. E.; Westlake, J.

    2016-03-01

    The Energetic Particle Detector (EPD) Investigation is one of five particles and fields investigations on the Magnetospheric Multiscale (MMS) mission. This mission consists of four satellites operating in close proximity in elliptical, low-inclination orbits, and is focused upon the fundamental physics of magnetic reconnection. The Energetic Particle Detector (EPD) investigation aboard the four MMS spacecraft consists of two instrument designs, the EIS (Energetic Ion Spectrometer) and the FEEPS (Fly's Eye Electron Proton Spectrometer). This present paper describes FEEPS from an instrument physics and engineering point of view, and provides some test and calibration data to facilitate effective analysis and use of the flight data for scientific purposes.

  5. MHD-EPIC: Extended Magnetohydrodynamics with Embedded Particle-in-Cell Simulation of Ganymede's Magnetosphere.

    NASA Astrophysics Data System (ADS)

    Toth, G.; Daldorff, L. K. S.; Jia, X.; Gombosi, T. I.; Lapenta, G.

    2014-12-01

    We have recently developed a new modeling capability to embed theimplicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-USmagnetohydrodynamic model. The PIC domain can cover the regions wherekinetic effects are most important, such as reconnection sites. TheBATS-R-US code, on the other hand, can efficiently handle the rest ofthe computational domain where the MHD or Hall MHD description issufficient. As one of the very first applications of the MHD-EPICalgorithm (Daldorff et al. 2014, JCP, 268, 236) we simulate theinteraction between Jupiter's magnetospheric plasma with Ganymede'smagnetosphere, where the separation of kinetic and global scalesappears less severe than for the Earth's magnetosphere. Because theexternal Jovian magnetic field remains in an anti-parallel orientationwith respect to Ganymede's intrinsic magnetic field, magneticreconnection is believed to be the major process that couples the twomagnetospheres. As the PIC model is able to describe self-consistentlythe electron behavior, our coupled MHD-EPIC model is well suited forinvestigating the nature of magnetic reconnection in thisreconnection-driven mini-magnetosphere. We will compare the MHD-EPICsimulations with pure Hall MHD simulations and compare both modelresults with Galileo plasma and magnetic field measurements to assess therelative importance of ion and electron kinetics in controlling theconfiguration and dynamics of Ganymede's magnetosphere.

  6. Parameter estimation of magnetospheric particle distributions in the energy range 20 to 500 keV

    NASA Astrophysics Data System (ADS)

    Torkar, K. M.

    1982-04-01

    A computer program which analyzes the energy spectra of energetic magnetospheric particles is described. The instrument characteristics and experimental design of the geostationary satellite GEOS-2 which provided the raw data are indicated. The program is designed to run on a UNIVAC 1100/81 computer and requires a plotter and a terminal with basic display enhancement features. Three dimensional charts showing the spectral distribution of energetic electrons are included.

  7. Motion of charged particles in planetary magnetospheres with nonelectromagnetic forces

    NASA Technical Reports Server (NTRS)

    Huang, T. S.; Hill, T. W.; Wolf, R. A.

    1988-01-01

    Expressions are derived for the mirror point, the bounce period, the second adiabatic invariant, and the bounce-averaged azimuthal drift velocity as functions of equatorial pitch angle for a charged particle in a dipole magnetic field in the presence of centrifugal, gravitational, and Coriolis forces. These expressions are evaluated numerically, and the results are displayed graphically. The average azimuthal drift speed for a flux tube containing a thermal equilibrium plasma distribution is also evaluated.

  8. PAMELA's Measurements of Magnetospheric Effects on High Energy Solar Particles

    NASA Astrophysics Data System (ADS)

    de Nolfo, Georgia; Boezio, M.; Bravar, Ulisse; Bruno, A.; Christian, Eric R.; Martucci, M.; Merge, M.; Mocchiutti, E.; Munini, R.; Ricci, M.; Ryan, James Michael; Stochaj, Steven; Thakur, N.

    2015-04-01

    Whether solar energetic particles (SEP) attain energies in excess of a GeV through flare reconnection or through CME-driven shocks is still in debate today. Observations of the properties of SEPs relate both to the acceleration mechanisms at play but also to the influences experienced during transport. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument, provides new observations of SEPs that uniquely set apart the affects of acceleration from those of transport. PAMELA detects the composition and the angular distribution of the particles about the magnetic field, i.e. pitch angle distribution, over a broad energy range (from ~80 MeV to beyond one GeV) -- bridging a critical gap between space-based measurements and ground-based. We report on the observation of high-energy SEP data from PAMELA acquired during the 2012 May 17 ground level enhancement (GLE). These data exhibit differential anisotropies and thus transport features over the instrument rigidity range. SEP protons exhibit two distinct pitch angle distributions; a low-energy population that extends to 90° and a population that is beamed at high energies (> 1 GeV), consistent with neutron monitor measurements. The arrival of SEPs over a broad range in energy at Earth within 20 minutes sets strong constraints on the pitch angle distribution of SEPs originating at the Sun. To explain a low-energy SEP population that exhibits significant scattering or redistribution accompanied by a high-energy population that reaches the Earth relatively unaffected by dispersive transport effects, we postulate that the scattering or redistribution takes place locally. We believe these are the first comprehensive measurements of the effects of solar energetic particle transport in the Earth's magnetosheath.

  9. Double layer -- a particle accelerator in the magnetosphere

    SciTech Connect

    Fu, Xiangrong

    2015-07-16

    Slides present the material under the following topics: Introduction (What is a double layer (DL)? Why is it important? Key unsolved problems); Theory -- time-independent solutions of 1D Vlasov--Poisson system; Particle-in-cell simulations (Current-driven DLs); and Electron acceleration by DL (Betatron acceleration). Key problems include the generation mechanism, stability, and electron acceleration. In summary, recent observations by Van Allen Probes show large number of DLs in the outer radiation belt, associated with enhanced flux of relativistic electrons. Simulations show that ion acoustic double layers can be generated by field-aligned currents. Thermal electrons can gain energy via betatron acceleration in a dipole magnetic field.

  10. An overview of the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) mission

    NASA Technical Reports Server (NTRS)

    Baker, Daniel N.; Mason, Glenn M.; Figueroa, Orlando; Colon, G.; Watzin, J. G.; Aleman, Roberto M.

    1993-01-01

    The scientific objective of the NASA Small-class Explorer Mission SAMPEX is summarized. A brief history of the Small Explorer program is provided along with a description of the SAMPEX project development and structure. The spacecraft and scientific instrument configuration is presented. The orbit of SAMPEX has an altitude of 520 by 670 km and an 82 deg inclination. Maximum possible power is provided by articulated solar arrays that point continuously toward the sun. Highly sensitive science instruments point generally toward the local zenith, especially over the terrestrial poles, in order to measure optimally the galactic and solar cosmic ray flux. Energetic magnetospheric particle precipitation is monitored at lower geomagnetic latitudes. The spacecraft uses several innovative approaches including an optical fiber bus, powerful onboard computers, and large solid state memories (instead of tape recorders). Spacecraft communication and data acquisition are discussed, and the space- and ground-segment data flows are summarized. A mission lifetime of 3 years is sought with the goal of extending data acquisition over an even longer portion of the 11-year solar activity cycle.

  11. Magnetospheric Effects on High Energy Solar Particles: PAMELA Measurements

    NASA Astrophysics Data System (ADS)

    de Nolfo, G. A.; Boezio, M.; Ryan, J. M.; Christian, E. R.; Stochaj, S.; Bruno, A.; Mergè, M.; Martucci, M.; Ricci, M.; Mocchiutti, E.; Munini, R.; Bazilevskaya, G.; Bravar, U.

    2015-12-01

    Solar Energetic Particles (SEPs) are thought to be accelerated at the Sun by solar flares or by the shocks formed by Coronal Mass Ejections (CMEs). Even more elusive is the origin of the highest energy SEPs in so-called Ground Level Enhancements (GLEs). At these energies, the effects of transport are often minimal, providing an opportunity to investigate the problem of particle acceleration. However, the effects of transport en route to Earth often obscure the acceleration process(es). The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument provides new data that aid in separating the effects of acceleration and transport. Furthermore, PAMELA bridges a critical gap in energy between the low-energy space-based and highest-energy ground-based measurements. We report on recent PAMELA observations of high-energy SEPs and illustrate some of the governing effects of acceleration and transport with the first GLE of solar cycle 24, i.e., 2012 May 17. The PAMELA data of 2012 May 17 reveal two distinct spectral components, a low-energy SEP component that exhibits significant scattering or redistribution, accompanied by a high-energy component that reaches the Earth relatively unaffected by dispersive transport effects. We postulate that the scattering or redistribution at low energies takes place locally providing one of the first opportunities to witness the effects of SEP transport in the Earth's magnetosheath.

  12. Activation of the tail open part during the magnetospheric storm

    NASA Astrophysics Data System (ADS)

    Mishin, V. M.; Karavaev, Yu. A.; Sapronova, L. A.; Solovyev, S. I.

    2012-07-01

    In each polar cap (PC) we mark out "old PC" observed during quiet time before the event under consideration, and "new PC" that emerges during the substorm framing the old one and expanding the PC total area. Old and new PCs are the areas for the magnetosphere old and new tail lobes, respectively. The new lobe variable magnetic flux Ψ1 is usually assumed to be active, i.e. it provides the electromagnetic energy flux (Poynting flux) ɛ' transport from solar wind (SW) into the magnetosphere. The old lobe magnetic flux Ψ2 is supposed to be passive, i.e. it remains constant during the disturbance and does not participate in the transporting process which would mean the old PC electric field absolute screening from the convection electric field created by the magnetopause reconnection. In fact, screening is observed, but far from absolute. We suggest a model of screening and determine its quantitative characteristics in the selected superstorm. The coefficient of a screening is the β = Ψ2/Ψ02, where Ψ02 = const is open magnetic flux through the old PC measured prior to the substorm, and Ψ2 is variable magnetic flux through the same area measured during the substorm. We consider three various regimes of disturbance. In each, the coefficient β decreased during the loading phase and increased at the unloading phase, but the rates and amplitudes of variations exhibited a strong dependence on the regime. We interpreted decrease in β as a result of involving the old PC magnetic flux Ψ2, which was considered to be constant earlier, in the Poynting flux ɛ' transport process from solar wind into the magnetosphere. Transport process weakening at the subsequent unloading phase creates increase in β. Estimates showed that coefficient β during each regime and the computed Poynting flux ɛ' varied manifolds. In general, unlike the existing substorm conception, the new scenario describes an unknown earlier of tail lobe activation process during a substorm growth phase that

  13. Particle-in-cell simulations of ion-acoustic waves with application to Saturn's magnetosphere

    SciTech Connect

    Koen, Etienne J.; Collier, Andrew B.; Hellberg, Manfred A.; Maharaj, Shimul K.

    2014-07-15

    Using a particle-in-cell simulation, the dispersion and growth rate of the ion-acoustic mode are investigated for a plasma containing two ion and two electron components. The electron velocities are modelled by a combination of two kappa distributions, as found in Saturn's magnetosphere. The ion components consist of adiabatic ions and an ultra-low density ion beam to drive a very weak instability, thereby ensuring observable waves. The ion-acoustic mode is explored for a range of parameter values such as κ, temperature ratio, and density ratio of the two electron components. The phase speed, frequency range, and growth rate of the mode are investigated. Simulations of double-kappa two-temperature plasmas typical of the three regions of Saturn's magnetosphere are also presented and analysed.

  14. Planetary magnetospheres

    NASA Technical Reports Server (NTRS)

    Stern, D. P.; Ness, N. F.

    1981-01-01

    A concise overview is presented of our understanding of planetary magnetospheres (and in particular, of that of the Earth), as of the end of 1981. Emphasis is placed on processes of astrophysical interest, e.g., on particle acceleration, collision-free shocks, particle motion, parallel electric fields, magnetic merging, substorms, and large scale plasma flows. The general morphology and topology of the Earth's magnetosphere are discussed, and important results are given about the magnetospheres of Jupiter, Saturn and Mercury, including those derived from the Voyager 1 and 2 missions and those related to Jupiter's satellite Io. About 160 references are cited, including many reviews from which additional details can be obtained.

  15. Enceladus' varying imprint on the magnetosphere of Saturn.

    PubMed

    Jones, G H; Roussos, E; Krupp, N; Paranicas, C; Woch, J; Lagg, A; Mitchell, D G; Krimigis, S M; Dougherty, M K

    2006-03-10

    The bombardment of Saturn's moon Enceladus by >20-kiloelectron volt magnetospheric particles causes particle flux depletions in regions magnetically connected to its orbit. Irrespective of magnetospheric activity, proton depletions are persistent, whereas electron depletions are quickly erased by magnetospheric processes. Observations of these signatures by Cassini's Magnetospheric Imaging Instrument allow remote monitoring of Enceladus' gas and dust environments. This reveals substantial outgassing variability at the moon and suggests increased dust concentrations at its Lagrange points. The characteristics of the particle depletions additionally provide key radial diffusion coefficients for energetic electrons and an independent measure of the inner magnetosphere's rotation velocity. PMID:16527968

  16. Global inner magnetosphere simulations with self-consistent wave-particle interactions

    NASA Astrophysics Data System (ADS)

    Jordanova, Vania

    2012-07-01

    Plasma waves play a fundamental role in the energization and loss of charged particles in the inner magnetosphere. The free energy for these waves is supplied from the anisotropic ring current ion and electron velocity distributions. We present a self-consistent study of plasma wave excitation during geomagnetic storms after the convective injection of plasma sheet particles into the inner magnetosphere. We use our kinetic ring current-atmosphere interactions model (RAM) to simulate ring current evolution during storms and compare the mechanisms responsible for trapping energetic particles and for causing their loss. Our model retains four dimensions (4-D) and includes time-dependent convective transport and radial diffusion, all major loss processes, and is coupled with a dynamic 2-D plasmasphere model. The boundary conditions are specified from LANL data measured at geosynchronous orbit. We calculate the pitch angle anisotropy of ring current ions and electrons and identify equatorial regions for potential growth of electromagnetic ion cyclotron (EMIC) waves or whistler-mode waves. We find that the linear growth rate of whistler-mode waves maximizes in the dawn local time sector, while EMIC waves are most intense in the afternoon sector in agreement with previous satellite observations. Pitch angle scattering by EMIC waves causes significant particle precipitation into the atmosphere and reduction of radiation belt electron and ring current ion fluxes.

  17. Improving realtime predictions of magnetospheric activities using STEREO Space Weather Beacon

    NASA Astrophysics Data System (ADS)

    Bala, R.; Reiff, P. H.

    2011-12-01

    The Rice neural network models of geomagnetic activity indices Kp, Dst and AE (available from \\url{http://mms.rice.edu/realtime/forecast.html}), driven by the ACE solar wind data, have been actively running in near-realtime mode to provide short-term predictions of magnetospheric activities; subscribers to our ``spacalrt" system receive email alerts and notices of space weather based on key discriminator levels. Active structures that are likely to erupt on the sun and resulting in solar flares and/or Coronal Mass Ejections (CMEs) are now being well imaged by instruments aboard STEREO, which also provides multipoint, realtime and continuous information of the solar wind, interplanetary magnetic field, solar energetic particles through its Space Weather Beacon IMPACT and PLASTIC. The spacecraft lagging Earth (STEREO-B) and being ahead in the Parker spiral, is well suited to provide longer lead times to predictions of any common measures of geoeffectiveness resulting from solar wind-magnetospheric interactions such as Kp, Dst and AE indices. As our models are constantly evolving, our desire to drive them by indulging these advanced instruments is to provide longer lead times. Furthermore, this paper also investigates the geoeffectiveness of predicting CME-driven storms.

  18. Extended magnetohydrodynamics with embedded particle-in-cell simulation of Ganymede's magnetosphere

    NASA Astrophysics Data System (ADS)

    Tóth, Gábor; Jia, Xianzhe; Markidis, Stefano; Peng, Ivy Bo; Chen, Yuxi; Daldorff, Lars K. S.; Tenishev, Valeriy M.; Borovikov, Dmitry; Haiducek, John D.; Gombosi, Tamas I.; Glocer, Alex; Dorelli, John C.

    2016-02-01

    We have recently developed a new modeling capability to embed the implicit particle-in-cell (PIC) model iPIC3D into the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme magnetohydrodynamic (MHD) model. The MHD with embedded PIC domains (MHD-EPIC) algorithm is a two-way coupled kinetic-fluid model. As one of the very first applications of the MHD-EPIC algorithm, we simulate the interaction between Jupiter's magnetospheric plasma and Ganymede's magnetosphere. We compare the MHD-EPIC simulations with pure Hall MHD simulations and compare both model results with Galileo observations to assess the importance of kinetic effects in controlling the configuration and dynamics of Ganymede's magnetosphere. We find that the Hall MHD and MHD-EPIC solutions are qualitatively similar, but there are significant quantitative differences. In particular, the density and pressure inside the magnetosphere show different distributions. For our baseline grid resolution the PIC solution is more dynamic than the Hall MHD simulation and it compares significantly better with the Galileo magnetic measurements than the Hall MHD solution. The power spectra of the observed and simulated magnetic field fluctuations agree extremely well for the MHD-EPIC model. The MHD-EPIC simulation also produced a few flux transfer events (FTEs) that have magnetic signatures very similar to an observed event. The simulation shows that the FTEs often exhibit complex 3-D structures with their orientations changing substantially between the equatorial plane and the Galileo trajectory, which explains the magnetic signatures observed during the magnetopause crossings. The computational cost of the MHD-EPIC simulation was only about 4 times more than that of the Hall MHD simulation.

  19. Global electric field determination in the Earth's outer magnetosphere using charged particles

    NASA Technical Reports Server (NTRS)

    Eastman, T.; Sheldon, R.; Hamilton, D.; Mcilwain, C.

    1992-01-01

    Although many properties of the Earth's magnetosphere have been measured and quantified in the past 30 years since it was discovered, one fundamental (for a zeroeth order magnetohydrodynamic (MHD) equilibrium) measurement was made infrequently and with poor spatial coverage: the global electric field. This oversight is in part due to the difficulty of measuring a plasma electric field, and in part due to the difficulty of measuring a plasma electric field, and in part due to the neglect of theorists. However, there is renewed interest in the convection electric field, since it has been realized that it is vital for understanding many aspects of the magnetosphere: the global MHD equilibrium, reconnection rates, Region 2 Birkeland currents, magnetosphere-ionosphere coupling, ring current and radiation belt transport, substorm injections, acceleration mechanisms, etc. Unfortunately the standard experimental methods have not been able to synthesize a global field (excepting the pioneering work of McIlwain's geostationary models), and we are left with an overly simplistic theoretical field, the Volland-Stern electric field mode. Again, single point measurements of the plasma pause were used to infer the appropriate amplitudes of the model, parameterized by Kp (Maynard & Chen, JGR 1975). Although this result was never intended to be the definitive electric field model, it has gone nearly unchanged for 15 years. However, the data sets being taken today require a great deal more accuracy than can be provided by the Volland-Stern model. Nor has the variability of the electric field shielding been properly addressed, although effects of penetrating magnetospheric electric fields has been seen in mid- and low-latitude ionospheric data sets. The growing interests in substorm dynamics also requires a much better assessment of the electric fields responsible for particle injections. Thus, we proposed and developed algorithms for extracting electric fields from particle data

  20. Small Explorers - Small is beautiful. [Solar, Anomalous, and Magnetospheric Particles Explorer (SAMPEX)

    NASA Technical Reports Server (NTRS)

    Gilman, David

    1990-01-01

    NASA's Small Explorer Program aims to achieve a flight rate of one mission per year in a program of small scientific satellites launched from small expendable launch vehicles. The Program is developing 3 missions for launch in the early 1990's: the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX), the Submillimeter Wave Astronomy Satellite (SWAS), and the Fast Auroral Snapshot Explorer (FAST). This paper gives an overview of the program, a description of the selected missions, the approach to developing the missions and the plans for the next Announcement of Opportunity.

  1. Particle entry into the inner magnetosphere during duskward IMF By: Global three-dimensional electromagnetic full particle simulations

    NASA Astrophysics Data System (ADS)

    Cai, D.; Yan, X. Y.; Nishikawa, K.-I.; Lembege, B.

    2006-06-01

    The change of the interplanetary magnetic field (IMF) direction from northward to duskward has an important impact on the inner magnetosphere. This impact is analyzed with the help of a new parallel version of the global three-dimensional full particle simulation code. For northward IMF, bands of weak magnetic field (sash) form poleward of the cusp at high latitudes in each hemisphere. These sashes move to the equator (within opposite quadrants) as the IMF rotates duskward and merge into one another to form the characteristic ``Crosstail-S'' within the neutral sheet of the magnetotail. These macroscopic magnetic patterns (sashes and Crosstail-S) evidenced herein are in a good agreement with results of previous 3D MHD simulations and experimental observations. Moreover, the analysis of particle fluxes shows that ``sashes'' and ``Crosstail-S'' act as magnetic groove to facilitate the entry and injection of magnetosheath particles into the inner magnetosphere. Injected particles are accelerated after the IMF changes its direction from northward to duskward.

  2. Global Explicit Particle-in-cell Simulations of the Nonstationary Bow Shock and Magnetosphere

    NASA Astrophysics Data System (ADS)

    Yang, Zhongwei; Huang, Can; Liu, Ying D.; Parks, George K.; Wang, Rui; Lu, Quanming; Hu, Huidong

    2016-07-01

    We carry out two-dimensional global particle-in-cell simulations of the interaction between the solar wind and a dipole field to study the formation of the bow shock and magnetosphere. A self-reforming bow shock ahead of a dipole field is presented by using relatively high temporal-spatial resolutions. We find that (1) the bow shock and the magnetosphere are formed and reach a quasi-stable state after several ion cyclotron periods, and (2) under the B z southward solar wind condition, the bow shock undergoes a self-reformation for low β i and high M A . Simultaneously, a magnetic reconnection in the magnetotail is found. For high β i and low M A , the shock becomes quasi-stationary, and the magnetotail reconnection disappears. In addition, (3) the magnetopause deflects the magnetosheath plasmas. The sheath particles injected at the quasi-perpendicular region of the bow shock can be convected downstream of an oblique shock region. A fraction of these sheath particles can leak out from the magnetosheath at the wings of the bow shock. Hence, the downstream situation is more complicated than that for a planar shock produced in local simulations.

  3. E.l.f./v.l.f. emissions observed on Ariel 4. [wave-particle phenomena in magnetosphere

    NASA Technical Reports Server (NTRS)

    Bullough, K.; Denby, M.; Gibbons, W.; Hughes, A. R. W.; Kaiser, T. R.; Tatnall, A. R. L.

    1975-01-01

    The Ariel 4 satellite was designed to study wave-particle phenomena in the magnetosphere by measuring the electromagnetic wave fields over a wide frequency range and the fluxes and pitch angle distributions of energetic particles. We describe here the results of a preliminary study of the various v.l.f./e.l.f. electromagnetic wave phenomena which are observed. These include man-made signals from v.l.f. transmitters, impulsive noise originating in thunderstorms and emissions arising from magnetospheric energetic charged particles.

  4. Comment on 'Mapping the dayside ionosphere to the magnetosphere according to particle precipitation characteristics' by Newell and Meng

    NASA Technical Reports Server (NTRS)

    Lockwood, M.; Smith, M. F.

    1993-01-01

    Newell and Meng (1992) present maps of the occurrence probability of various classifications of particle precipitation as seen in the dayside topside ionosphere. It is argued that these are maps of the magnetospheric regions, a contention with which their critics disagree. The latter conclude that, because of convection, any one population of particles seen at low altitudes will have originated from a wide variety of locations, and particle characteristics cannot be mapped back to those in the magnetosphere without detailed knowledge of both the convection and magnetic field. Steplike boundaries between the regions will arise from nonsteady-state conditions and cannot be envisaged as steady-state magnetospheric boundaries between two plasma populations. In their reply Newell and Meng contend that convection does not move plasma from the LLBL into the cusp. Most of the LLBL plasma comes from the magnetosheath, so the direction of plasma transfer is in the other direction.

  5. Cluster Active Archive products and multipoint magnetospheric investigations

    NASA Astrophysics Data System (ADS)

    Perry, C.; Laakso, H.; Taylor, M.; Escoubet, P.

    2007-12-01

    The four-satellite Cluster mission investigates the small-scale structures (in three dimensions) of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. The Cluster Active Archive CAA (http://caa.estec.esa.int/) contains the entire set of Cluster high resolution data and other allied products in a standard format. The CAA currently has data from most of the Cluster instruments for at least the first three years of operations (2001-2003). The coverage and range of products is being continually improved with more than 200 datasets available from each spacecraft including high-resolution magnetic & electric DC fields and wave spectra; full 3D electron & ion distributions from a few eV to hundreds of keV; and various ancillary & browse products to help with spacecraft and event location. The data archived are (1) publicly accessible, (2) of the best quality achievable with the given resources, and (3) suitable for science use and publication by both the Cluster and broader scientific community. The presentation contains examples of user friendly services of the CAA for searching and accessing these data and ancillary products and of online capabilities of the system.

  6. Comparison of diffusion and particle drift descriptions of radial transport in the earth's inner magnetosphere

    SciTech Connect

    Riley, P.; Wolf, R.A. )

    1992-11-01

    The paper compares two approaches for describing the radial motion of charged particles in the equatorial plane of the earth's magnetosphere: the radial diffusion and the guiding-center drift. For this purpose, a time-dependent observation-based model electrostatic field is computed for the August 1990 storm event, and this field is used to (1) calculate the guiding-center drift of a ring of monoenergetic test particles and (2) compute the specific radial diffusion coefficient and solve the relevant diffusion equation. Generally, only fair agreement was found between the guiding-center and the diffusion calculation approaches. The best agreement could be obtained for the case of a series of small storms rather than for one substantial storm. 42 refs.

  7. Dynamically important wave-particle interactions in solar wind - magnetosphere - ionosphere coupling: A review

    NASA Astrophysics Data System (ADS)

    Cairns, Iver

    2012-07-01

    As plasma waves grow or damp they extract or deposit energy, respectively, and alter the phase-space gradients of particle distributions, perhaps leading to instability or damping of other waves. In addition, wave electric and magnetic fields can scatter particles in both position and velocity, altering their motion and sometimes energizing them or causing them to escape or enter physical regions of interest. Plasma waves can also be used to diagnose plasma properties (e.g., the density and magnetic field strength) and the presence of nonthermal particles. Nevertheless, even though plasma waves can heat, cool, energize, scatter, reflect, and characterize plasma particles the question remains: Are plasma waves actually dynamically important in space plasmas? Here this question is addressed in the context of solar wind - magnetosphere - ionosphere coupling by considering multiple regions where plasma waves might be dynamically important. These include: the slowing of the solar wind upstream of the bow shock associated with Fermi acceleration; heating and thermalization at the bow shock; limitation of the electron and ion temperature anisotropies and electron heat flux in the solar wind and magnetosheath; heating, flows, and particle acceleration in magnetic reconnection regions in Earth's magnetotail and magnetopause; precipitation of radiation belt particles into the loss cone and thence the ionosphere; and the development of auroral plasma cavities. In each case existing observations and theory are reviewed and compared, focusing on the importance to the plasma dynamics of plasma waves versus ``static'' macroscopic fields and other effects.

  8. Correlation between convection electric fields in the nightside magnetosphere and several wave and particle phenomena during two isolated substorms.

    NASA Technical Reports Server (NTRS)

    Carpenter, D. L.; Fraser-Smith, A. C.; Unwin, R. S.; Hones, E. W., Jr.; Heacock, R. R.

    1971-01-01

    Correlation of several magnetoionospheric wave and particle phenomena previously linked observationally to magnetospheric substorms and inferred to involve convection electric fields with whistler measurements of convection activity during two relatively isolated substorms. The events occurred at about 0600 UT on July 15, 1965, and about 0500 UT on Oct. 13, 1965. The correlated phenomena include cross-L inward plasma drifts near midnight within the plasmaphere, diffuse auroral radar echoes observed near the dusk meridian, IPDP micropulsations (intervals of pulsations of diminishing period) in the premidnight sector, apparent contractions and expansions of the plasma sheet at about 20 earth radii in the magnetotail, and Pc 1/Pi 1 micropulsation events near or before midnight. Two new vlf phenomena occurred during the October 13 event - a noise band within the plasmasphere associated with a convecting whistler path, and ?hisslers,' falling-tone auroral-hiss forms repeated at intervals of about 2 sec.

  9. Extended Magnetohydrodynamics with Embedded Particle-in-Cell (XMHD-EPIC) Simulations of Magnetospheric Reconnection

    NASA Astrophysics Data System (ADS)

    Toth, Gabor; Gombosi, Tamas; Jia, Xianzhe; Welling, Daniel; Chen, Yuxi; Haiducek, John; Jordanova, Vania; Peng, Ivy Bo; Markidis, Stefano; Lapenta, Giovanni

    2016-04-01

    We have recently developed a new modeling capability to embed the implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US extended magnetohydrodynamic model. The PIC domain can cover the regions where kinetic effects are most important, such as reconnection sites. The BATS-R-US code with its block-adaptive grid can efficiently handle the rest of the computational domain where the MHD or Hall MHD description is sufficient. The current implementation of the MHD-EPIC model allows two-way coupled simulations in two and three dimensions with multiple embedded PIC regions. The MHD and PIC grids can have different grid resolutions and grid structures. The MHD variables and the moments of the PIC distribution functions are interpolated and message passed in an efficient manner through the Space Weather Modeling Framework (SWMF). Both BATS-R-US and iPIC3D are massively parallel codes fully integrated into, run by and coupled through the SWMF. We have successfully applied the MHD-EPIC code to model Ganymede's and Mercury's magnetospheres. We compared our results with Galileo and MESSENGER magnetic observations, respectively, and found good overall agreement. We will report our progress on modeling the Earth magnetosphere with MHD-EPIC with the goal of providing direct comparison with and global context for the MMS observations.

  10. Titan's induced magnetosphere from plasma wave, particle data and magnetometer observations

    NASA Astrophysics Data System (ADS)

    Modolo, R.; Romanelli, N.; Canu, P.; Coates, A. J.; Berthelier, J.; Bertucci, C.; Leblanc, F.; Piberne, R.; Edberg, N. J.; Kurth, W. S.; Gurnett, D. A.; Wahlund, J.

    2013-12-01

    The Magnetometer (MAG) measurements, the particle data (CAPS) are combined with the Radio and Plasma Wave Science (RPWS) observations to provide an overall and organized description of the electron plasma environment and the pickup ion distribution around Titan. RPWS observations are used to measure the electron number density of the thermal plasma close to Titan. This data set is combined with CAPS-ELS electron number density in Saturn's magnetosphere and Titan's environment. A relatively good correspondence between the number density estimated from CAPS-ELS and RPWS are most of the time observed between 0.1 - 1 cm-3. Combining both ELS and RPWS data allows deducing a continuous electron density profile going from Saturn's magnetosphere to Titan's ionosphere leading to a global electron density map in Titan's vicinity. The MAG observations are used to derive information about the ambient magnetic field environment in the vicinity of Titan and also to emphasize the bipolar tail region. Ion information such the mass composition of the plasma and ion distribution function for specific time intervals are determined from CAPS-IMS. Pick-up ions have been identified from their energy signature and mass composition for few flybys. These observations also emphasized a ring distribution, characteristic of pick-up ions. The pick-up observations, in the DRAP coordinate system, are found to be located in the +E=-vxB hemisphere as expected.

  11. Electron ECHO 6: a study by particle detectors of electrons artificially injected into the magnetosphere

    SciTech Connect

    Malcolm, P.R.

    1986-01-01

    The ECHO-6 sounding rocket was launched from the Poke Flat Research Range, Alaska on 30 March 1983. A Terrier-Black Brant launch vehicle carried the payload on a northward trajectory over an auroral arc and to an apogee of 216 kilometers. The primary objective of the ECHO-6 experiment was to evaluate electric fields, magnetic fields, and plasma processes in the distant magnetosphere by injecting electron beams in the ionosphere and observing conjugate echoes. The experiment succeeded in injection 10-36 keV beams during the existence of a moderate growth-phase aurora, an easterly electrojet system, and a pre-midnight inflation condition of the magnetosphere. The ECHO-6 payload system consisted of an accelerator MAIN payload, a free-flying Plasma Diagnostics Package (PDP), and four rocket-propelled Throw Away Detectors (TADs). The PDP was ejected from the MAIN payload to analyze electric fields, plasma particles, energetic electrons, and photometric effects produced by beam injections. The TADs were ejected from the MAIN payload in a pattern to detect echoes in the conjugate echo region south of the beam-emitting MAIN payload. The TADs reached distances exceeding 3 kilometers from the MAIN payload and made measurements of the ambient electrons by means of solid-state detectors and electrostatic analyzers.

  12. Earth's Magnetosphere 3D Simulation by Coupling Particle-In-Cell and Magnetohydrodynamics Models: Parametric Study

    NASA Astrophysics Data System (ADS)

    Baraka, S. M.; Ben-Jaffel, L. B.

    2014-12-01

    We use particle-in-cell PIC 3D Electromagnetic, relativistic global code to address large-scale problems in magnetosphere electrodynamics. Terrestrial bow shock is simulated as an example. 3D Magnetohydrodynamics model ,MHD GUMICS in CCMC project, have been used in parallel with PIC under same scaled Solar wind (SW) and IMF conditions. We report new results from the coupling between the two models. Further investigations are required for confirmations of these results. In both codes the Earth's bow shock position is found at ~14.8 RE along the Sun-Earth line, and ~29 RE on the dusk side which is consistent with past in situ observation. Both simulations reproduce the theoretical jump conditions at the shock. However, PIC code density and temperature distributions are inflated and slightly shifted sunward when compared to MHD results. Reflected ions upstream of the bow shock may cause this sunward shift for density and temperature. Distribution of reflected ions and electrons are shown in the foreshock region, within the transition of the shock and in the downstream. The current version of PIC code can be run under modest computing facilities and resources. Additionally, existing MHD simulations should be useful to calibrate scaled properties of plasma resulting from PIC simulations for comparison with observations. Similarities and drawbacks of the results obtained by the two models are listed. The ultimate goal of using these different models in a complimentary manner rather than competitive is to better understand the macrostructure of the magnetosphere

  13. Equatorial drift paths of plasma particles in the mead-fairfield magnetospheric model

    NASA Astrophysics Data System (ADS)

    Ondoh, T.; Aikyo, K.

    1986-03-01

    Some characteristics of the Mead-Fairfield (MF) geomagnetic field in the equatorial plane under the superquiet (SQ) and superdisturbed (SD) conditions are presented. Drift paths of plasma particles with zero energy and various energies in the equatorial plane of the MF-SQ and MF-SD geomagnetic fields are computed for uniform dawn-dusk electric fields of 0.1 mV/m and 0.4 mV/m. The results are discussed in relation to the magnetospheric structures. The equatorial drift paths of zero energy particles in the 0.1 mV/m field and MF-SQ and MF-SD fields are found to be asymmetric with respect to the noon-midnight meridian. A trapped particle region or a closed drift path which does not circle the earth is found between 13 and 18 earth radii beyond the stagnation point of zero energy particles for a 0.1 mV/m electric field and the SD geomagnetic field.

  14. Investigation of tenuous plasma environment using Active Spacecraft Potential Control (ASPOC) on Magnetospheric Multiscale (MMS) Mission

    NASA Astrophysics Data System (ADS)

    Nakamura, Rumi; Jeszenszky, Harald; Torkar, Klaus; Andriopoulou, Maria; Fremuth, Gerhard; Taijmar, Martin; Scharlemann, Carsten; Svenes, Knut; Escoubet, Philippe; Prattes, Gustav; Laky, Gunter; Giner, Franz; Hoelzl, Bernhard

    2015-04-01

    The NASA's Magnetospheric Multiscale (MMS) Mission is planned to be launched on March 12, 2015. The scientific objectives of the MMS mission are to explore and understand the fundamental plasma physics processes of magnetic reconnection, particle acceleration and turbulence in the Earth's magnetosphere. The region of scientific interest of MMS is in a tenuous plasma environment where the positive spacecraft potential reaches an equilibrium at several tens of Volts. An Active Spacecraft Potential Control (ASPOC) instrument neutralizes the spacecraft potential by releasing positive charge produced by indium ion emitters. ASPOC thereby reduces the potential in order to improve the electric field and low-energy particle measurement. The method has been successfully applied on other spacecraft such as Cluster and Double Star. Two ASPOC units are present on each of the MMS spacecraft. Each unit contains four ion emitters, whereby one emitter per instrument is operated at a time. ASPOC for MMS includes new developments in the design of the emitters and the electronics enabling lower spacecraft potentials, higher reliability, and a more uniform potential structure in the spacecraft's sheath compared to previous missions. Model calculations confirm the findings from previous applications that the plasma measurements will not be affected by the beam's space charge. A perfectly stable spacecraft potential precludes the utilization of the spacecraft as a plasma probe, which is a conventional technique used to estimate ambient plasma density from the spacecraft potential. The small residual variations of the potential controlled by ASPOC, however, still allow to determine ambient plasma density by comparing two closely separated spacecraft and thereby reconstructing the uncontrolled potential variation from the controlled potential. Regular intercalibration of controlled and uncontrolled potentials is expected to increase the reliability of this new method.

  15. Results of an ISEE-1 experiment to study the interactions between energetic particles and discrete VLF waves in the magnetosphere

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Despite the malfunctioning of the digital portion of the experiment which is encoding the absolute amplitude of the wave spectrum with a fixed bias of approximately 20 dB, the analog portion of the instrument is acquiring excellent data concerning the wave function and relative amplitude. Results obtained over a 2-year period which have important implications for magnetospheric wave-particle interactions are examined in the areas of emission generation by nonconducted coherent waves, and cold plasma distribution in the inner magnetosphere.

  16. Motions of charged particles in the Magnetosphere under the influence of a time-varying large scale convection electric field

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Bewtra, N. K.; Hoffman, R. A.

    1979-01-01

    The motions of charged particles under the influence of the geomagnetic and electric fields were quite complex in the region of the inner magnetosphere. The Volland-Stern type large scale convection electric field was used successfully to predict both the plasmapause location and particle enhancements determined from Explorer 45 measurements. A time dependence in this electric field was introduced based on the variation in Kp for actual magnetic storm conditions. The particle trajectories were computed as they change in this time-varying electric field. Several storm fronts of particles of different magnetic moments were allowed to be injected into the inner magnetosphere from L = 10 in the equatorial plane. The motions of these fronts are presented in a movie format.

  17. Spatial structure and temporal evolution of energetic particle injections in the inner magnetosphere during the 14 July 2013 substorm event

    SciTech Connect

    Gkioulidou, Matina; Ohtani, S.; Mitchell, D. G.; Ukhorskiy, A. Y.; Reeves, G. D.; Turner, D. L.; Gjerloev, J. W.; Nosé, M.; Koga, K.; Rodriguez, J. V.; Lanzerotti, L. J.

    2015-03-20

    Recent results by the Van Allen Probes mission showed that the occurrence of energetic ion injections inside geosynchronous orbit could be very frequent throughout the main phase of a geomagnetic storm. Understanding, therefore, the formation and evolution of energetic particle injections is critical in order to quantify their effect in the inner magnetosphere. We present a case study of a substorm event that occurred during a weak storm (Dst ~ –40 nT) on 14 July 2013. Van Allen Probe B, inside geosynchronous orbit, observed two energetic proton injections within 10 min, with different dipolarization signatures and duration. The first one is a dispersionless, short-timescale injection pulse accompanied by a sharp dipolarization signature, while the second one is a dispersed, longer-timescale injection pulse accompanied by a gradual dipolarization signature. We combined ground magnetometer data from various stations and in situ particle and magnetic field data from multiple satellites in the inner magnetosphere and near-Earth plasma sheet to determine the spatial extent of these injections, their temporal evolution, and their effects in the inner magnetosphere. Our results indicate that there are different spatial and temporal scales at which injections can occur in the inner magnetosphere and depict the necessity of multipoint observations of both particle and magnetic field data in order to determine these scales.

  18. Spatial structure and temporal evolution of energetic particle injections in the inner magnetosphere during the 14 July 2013 substorm event

    DOE PAGESBeta

    Gkioulidou, Matina; Ohtani, S.; Mitchell, D. G.; Ukhorskiy, A. Y.; Reeves, G. D.; Turner, D. L.; Gjerloev, J. W.; Nosé, M.; Koga, K.; Rodriguez, J. V.; et al

    2015-03-20

    Recent results by the Van Allen Probes mission showed that the occurrence of energetic ion injections inside geosynchronous orbit could be very frequent throughout the main phase of a geomagnetic storm. Understanding, therefore, the formation and evolution of energetic particle injections is critical in order to quantify their effect in the inner magnetosphere. We present a case study of a substorm event that occurred during a weak storm (Dst ~ –40 nT) on 14 July 2013. Van Allen Probe B, inside geosynchronous orbit, observed two energetic proton injections within 10 min, with different dipolarization signatures and duration. The first onemore » is a dispersionless, short-timescale injection pulse accompanied by a sharp dipolarization signature, while the second one is a dispersed, longer-timescale injection pulse accompanied by a gradual dipolarization signature. We combined ground magnetometer data from various stations and in situ particle and magnetic field data from multiple satellites in the inner magnetosphere and near-Earth plasma sheet to determine the spatial extent of these injections, their temporal evolution, and their effects in the inner magnetosphere. Our results indicate that there are different spatial and temporal scales at which injections can occur in the inner magnetosphere and depict the necessity of multipoint observations of both particle and magnetic field data in order to determine these scales.« less

  19. Particle Acceleration in Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Miller, James A.

    1996-01-01

    The investigation of stochastic particle acceleration through resonant interactions with plasma waves that populate the magnetosphere surrounding an accreting black hole is presented. Stochastic acceleration has been successfully applied to the problem of ion and electron energization in solar flares, and is capable of accounting for a wide range of both neutral and charged particle emissions. It is also a component in diffusive shock acceleration, since pitch-angle scattering (which is necessary for multiple shock crossings) is accompanied by diffusion in momentum space, which in turn yields a net systematic energy gain; however, stochastic energization will dominate the first-order shock process only in certain parameter regimes. Although stochastic acceleration has been applied to particle energization in the lobes of radio galaxies, its application to the central regions of AGNs (active galactic nuclei) has only recently been considered, but not in detail. We proposed to systematically investigate the plasma processes responsible for stochastic particle acceleration in black hole magnetospheres along with the energy-loss processes which impede particle energization. To this end, we calculated acceleration rates and escape time scales for protons and electrons resonating with Alfven waves, and for electrons resonating with whistlers. We also considered the "hot" topic of gamma-ray line emission from the Orion complex. We proposed that the observed gamma-ray lines are produced by energetic ions that are stochastically accelerated by cascading Alfven waves in the accretion plasma near a black hole. Related research papers that were published in journals are listed.

  20. Magnetospheric Simulations With the Three-Dimensional Magnetohydrodynamics With Embedded Particle-in-Cell Model

    NASA Astrophysics Data System (ADS)

    Toth, G.; Jia, X.; Chen, Y.; Markidis, S.; Peng, B.; Daldorff, L. K. S.; Tenishev, V.; Borovikov, D.; Haiducek, J. D.; Gombosi, T. I.; Glocer, A.; Dorelli, J.; Lapenta, G.

    2015-12-01

    We have recently developed a new modeling capability to embed the implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US magnetohydrodynamic model. The PIC domain can cover the regions where kinetic effects are most important, such as reconnection sites. The BATS-R-US code, on the other hand, can efficiently handle the rest of the computational domain where the MHD or Hall MHD description is sufficient with its block-adaptive grid. The current implementation of the MHD-EPIC model allows two-way coupled simulations in two and three dimensions with multiple embedded PIC regions. The MHD and PIC grids can have different grid resolutions. The MHD variables and the moments of the PIC distribution functions are interpolated and message passed in an efficient manner through the Space Weather Modeling Framework (SWMF). Both BATS-R-US and iPIC3D are massively parallel codes fully integrated into, run by and coupled through the SWMF. We have successfully applied the MHD-EPIC code to model Ganymede's magnetosphere. Using four PIC regions we have in effect performed a fully kinetic simulation of the moon's mini-magnetosphere with a grid resolution that is about 5 times finer than the ion inertial length. The Hall MHD model provides proper boundary conditions for the four PIC regions and connects them with each other and with the inner and outer outer boundary conditions of the much larger MHD domain. We compare our results with Galileo magnetic observations and find good overall agreement with both Hall MHD and MHD-EPIC simulations. The power spectrum for the small scale fluctuations, however, agrees with the data much better for the MHD-EPIC simulation than for Hall MHD. In the MHD-EPIC simulation, unlike in the pure Hall MHD results, we also find signatures of flux transfer events (FTEs) that agree very well with the observed FTE signatures both in terms of shape and amplitudes. We will also highlight our ongoing efforts to model the magnetospheres of Mercury and

  1. Low-energy particles at the bow shock, magnetopause, and outer magnetosphere of Saturn

    SciTech Connect

    Maclennan, C.G.; Lanzerotti, L.J.; Krimigis, S.M.; Lepping, R.P.

    1983-11-01

    Low-energy electron (>22 keV) and protons (> or approx. =30 keV) measured by the Low-Energy Charged Particle Experiment (LECP) during the encounters of the two Voyager spacecraft with Saturn are described. The characteristics of the dayside bow shock, magnetopause, and outer magnetosphere are emphasized. Only one crossing of the Saturian bow shock was observed inbound during the Voyager 1 encounter, whereas five crossings of the bow shock were identified during the Voyager 2 approach to the planet. During several of these bow shock crossings, low energy protons were observed to be streaming from the direction of the dawnside of the magnetosphere. In the magnetosheath the protons were observed to be oriented primarily with pitch angles of approx.90/sup 0/. Prior to the inbound magnetopause crossings (as defined by the magnetometer experiment on Voyager), the low-energy protons and electrons were observed to increase in intensity. Further, during Voyager 2 encounter, an increase in the proton and electron fluxes accompanied a change in orientation of the magnetosheath magnetioc field from one with a vertical component opposite to the planetary field to one with a vertical component in the direction of the planetary field. Examination of the flux distributions of the protons suggests that the magnetopuase was moving inward with a lower limit speed of approx.10 km/s during the Voyager 2 approach to the planet. The observed average subsolar magnetopause position at the time of Voyager 2 encounter was 18.5 R/sub S/, whereas during the Voyager 1 encounter it was considerably more extended, at 23.5 R/sub S/.

  2. Pulsars Magnetospheres

    NASA Technical Reports Server (NTRS)

    Timokhin, Andrey

    2012-01-01

    Current density determines the plasma flow regime. Cascades are non-stationary. ALWAYS. All flow regimes look different: multiple components (?) Return current regions should have particle accelerating zones in the outer magnetosphere: y-ray pulsars (?) Plasma oscillations in discharges: direct radio emission (?)

  3. Multifractal features of magnetospheric dynamics and their dependence on solar activity

    NASA Astrophysics Data System (ADS)

    Gopinath, Sumesh

    2016-09-01

    In the present study, novel wavelet leaders (WL) based multifractal analysis has been used to get a better knowledge of the self-organization phenomena inherent in complex magnetospheric dynamics during disturbance and quiescent periods, focusing mainly on the intermittent features of auroral electrojet (AE) index. The results derived from the analysis certainly exhibit the phase transition property of magnetosphere system with respect to variabilities in the driving conditions. By using the novel WL method, solar activity dependence/independence of intermittency of magnetospheric proxies such as AE, SYM-H and Dst indices have been compared. The results indicate that the multifractality of AE index does not follow the solar activity cycle while intermittent features of SYM-H and Dst indices show high degree of solar activity dependence. This shows that along with the external solar wind perturbations, certain complex phenomena of internal origin also significantly modulate the dynamics of geomagnetic fluctuations in the auroral region.

  4. Energetic Particle Spectral Shapes in Planetary Magnetospheres; Assessment of the Kappa Function

    NASA Astrophysics Data System (ADS)

    Mauk, B.

    2015-12-01

    In assessing the efficacy of the kappa distribution function in space environments, it is useful to follow two paths. First, to what extent do we consider the kappa function (or any function) to represent some kind of universal spectral shape that indicates common physical processes occurring in a wide diversity of space environments? Second, how useful is the kappa function in quantitatively characterizing observed spectral shapes, particularly for the purpose permitting further quantitative analyses of the environment (e. g. wave growth). In this report I evaluate the efficacy of the kappa distribution in representing energetic particle spectral shapes in planetary magnetospheres from both perspectives. In particular, I expand on the extensive treatment provided by Carbary et al. (2014) by taking a more explicit comparative approach between the different planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and also focusing on the most intense (and therefore from my perspective the most interesting) spectra within each of these different planets. There is no question that the "power law tail" represents as close to a universal characteristic of planetary space environments as one could hope to find. Such a universal shape must represent some universality in the energization and/or equilibrating processes. Also, there is no question that such tails must (to be non-divergent) and do roll over to flatter shapes at lower energies. In a number of applications, this basic characteristic has been usefully characterized by the kappa function to extract such parameters of the system as flow velocities. However, at least for the more intense spectra at Earth, Jupiter, Saturn, and Uranus, the kappa function in fact does a relatively poor job in representing the low energy roll-over of energetic particle spectra. Other functional forms have been found to be much more useful for characterizing these spectral shapes over a broad range of energies. And specifically, a very

  5. Near-horizon Kerr magnetosphere

    NASA Astrophysics Data System (ADS)

    Gralla, Samuel E.; Lupsasca, Alexandru; Strominger, Andrew

    2016-05-01

    We exploit the near-horizon conformal symmetry of rapidly spinning black holes to determine universal properties of their magnetospheres. Analytic expressions are derived for the limiting form of the magnetosphere in the near-horizon region. The symmetry is shown to imply that the black hole Meissner effect holds for free Maxwell fields but is generically violated for force-free fields. We further show that in the extremal limit, near-horizon plasma particles are infinitely boosted relative to accretion flow. Active galactic nuclei powered by rapidly spinning black holes are therefore natural sites for high-energy particle collisions.

  6. FASTSAT-HSV01 synergistic observations of the magnetospheric response during active periods: MINI-ME, PISA and TTI

    NASA Astrophysics Data System (ADS)

    Casas, Joseph; Collier, Michael; Rowland, Douglas; Sigwarth, John; Boudreaux, Mark

    Understanding the complex processes within the inner magnetosphere of Earth particularly during storm periods requires coordinated observations of the particle and field environment using both in-situ and remote sensing techniques. In fact in order to gain a better understand-ing of our Heliophysics and potentially improve our space weather forecasting capabilities, new observation mission approaches and new instrument technologies which can provide both cost effective and robust regular observations of magnetospheric activity and other space weather related phenomenon are necessary. As part of the effort to demonstrate new instrument tech-niques and achieve necessary coordinated observation missions, NASA's Fast Affordable Sci-ence and Technology Satellite Huntsville 01 mission (FASTSAT-HSV01) scheduled for launch in 2010 will afford a highly synergistic solution which satisfies payload mission opportunities and launch requirements as well as contributing in the near term to our improved understanding of Heliophysics. NASA's FASTSAT-HSV01 spacecraft on the DoD Space Test Program-S26 (STP-S26) Mission is a multi-payload mission executed by the DoD Space Test Program (STP) at the Space Development and Test Wing (SDTW), Kirtland AFB, NM. and is an example of a responsive and economical breakthrough in providing new possibilities for small space technology-driven and research missions. FASTSAT-HSV is a unique spacecraft platform that can carry multiple small instruments or experiments to low-Earth orbit on a wide range of expendable launch vehicles for a fraction of the cost traditionally required for such missions. The FASTSAT-HSV01 mission allows NASA to mature and transition a technical capability to industry while increasing low-cost access to space for small science and technology (ST) payloads. The FASTSAT-HSV01 payload includes three NASA Goddard Space Flight Center (GSFC) new technology built instruments that will study the terrestrial space environment and

  7. Magnetospheric Convection Electric Field Dynamics and Stormtime Particle Energization: Case Study of the Magnetic Storm of May 4,1998

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Liemohn, Michael W.; Newman, Tim S.; Fok, Mei-Ching; Ridley, Aaron

    2003-01-01

    It is shown that narrow channels of high electric field are an effective mechanism for injecting plasma into the inner magnetosphere. Analytical expressions for the electric field cannot produce these channels of intense plasma flow, and thus result in less entry and energization of the plasma sheet into near-Earth space. For the ions, omission of these channels leads to an underprediction of the strength of the stormtime ring current and therefore an underestimation of the geoeffectiveness of the storm event. For the electrons, omission of these channels leads to the inability to create a seed population of 10-100 keV electrons deep in the inner magnetosphere. These electrons can eventually be accelerated into MeV radiation belt particles.

  8. Magnetospheres of the outer planets

    NASA Technical Reports Server (NTRS)

    Vanallen, James A.

    1987-01-01

    The five qualitatively different types of magnetism that a planet body can exhibit are outlined. Potential sources of energetic particles in a planetary magnetosphere are discussed. The magnetosphere of Uranus and Neptune are then described using Pioneer 10 data.

  9. PET - A proton/electron telescope for studies of magnetospheric, solar, and galactic particles

    NASA Technical Reports Server (NTRS)

    Cook, Walter R.; Cummings, Alan C.; Cummings, Jay R.; Garrard, Thomas L.; Kecman, Branislav; Mewaldt, Richard A.; Selesnick, Richard S.; Stone, Edward C.; Baker, Daniel N.; Von Rosenvinge, Tycho T.

    1993-01-01

    The Proton/Electron Telescope (PET) on SAMPEX is designed to provide measurements of energetic electrons and light nuclei from solar, galactic, and magnetospheric sources. PET is an all solid-state system that will measure the differential energy spectra of electrons from about 1 to about 30 MeV and H and He nuclei from about 20 to about 300 MeV/nuc, with isotope resolution of H and He extending from about 20 to about 80 MeV/nuc. As SAMPEX scans all local times and geomagnetic cutoffs over the course of its near-polar orbit, PET will characterize precipitating relativistic electron events during periods of declining solar activity, and it will examine whether the production rate of odd nitrogen and hydrogen molecules in the middle atmosphere by precipitating electrons is sufficient to affect O3 depletion. In addition, PET will complement studies of the elemental and isotopic composition of energetic heavy (Z greater than 2) nuclei on SAMPEX by providing measurements of H, He, and electrons. Finally, PET has limited capability to identify energetic positrons from potential natural and man-made sources.

  10. An ISEE 3 high time resolution study of interplanetary parameter correlations with magnetospheric activity

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Zwickl, R. D.; Bame, S. J.; Hones, E. W., Jr.; Tsurutani, B. T.; Smith, E. J.; Akasofu, S.-I.

    1983-01-01

    The coupling between the solar wind and the geomagnetic disturbances was examined using data from the ISEE-3 spacecraft at an earth-sun libration point and ground-based data. One minute data were used to avoid aliasing in determining the internal magnetospheric response to solar wind conditions. Attention was given to the cross-correlations between the geomagnetic index (AE), the total energy dissipation rate (UT), and the solar wind parameters, as well as the spatial and temporal scales on which the magnetosphere reacts to the solar wind conditions. It was considered necessary to characterize the physics of the solar wind-magnetosphere coupling in order to define the requirements for a spacecraft like the ISEE-3 that could be used as a real time monitoring system for predicting storms and substorms. The correlations among all but one parameter were lower during disturbance intervals; UT was highly correlated with all parameters during the disturbed times. An intrinsic 25-40 min delay was detected between interplanetary activity and magnetospheric response in quite times, diminishing to no more than 15 min during disturbed times.

  11. Young gamma-ray pulsar: from modeling the gamma-ray emission to the particle-in-cell simulations of the global magnetosphere

    NASA Astrophysics Data System (ADS)

    Brambilla, Gabriele; Kalapotharakos, Constantions; Timokhin, Andrey; Kust Harding, Alice; Kazanas, Demosthenes

    2016-04-01

    Accelerated charged particles flowing in the magnetosphere produce pulsar gamma-ray emission. Pair creation processes produce an electron-positron plasma that populates the magnetosphere, in which the plasma is very close to force-free. However, it is unknown how and where the plasma departs from the ideal force-free condition, which consequently inhibits the understanding of the emission generation. We found that a dissipative magnetosphere outside the light cylinder effectively reproduces many aspects of the young gamma-ray pulsar emission as seen by the Fermi Gamma-ray Space Telescope, and through particle-in-cell simulations (PIC), we started explaining this configuration self-consistently. These findings show that, together, a magnetic field structure close to force-free and the assumption of gamma-ray curvature radiation as the emission mechanism are strongly compatible with the observations. Two main issues from the previously used models that our work addresses are the inability to explain luminosity, spectra, and light curve features at the same time and the inconsistency of the electrodynamics. Moreover, using the PIC simulations, we explore the effects of different pair multiplicities on the magnetosphere configurations and the locations of the accelerating regions. Our work aims for a self-consistent modeling of the magnetosphere, connecting the microphysics of the pair-plasma to the global magnetosphere macroscopic quantities. This direction will lead to a greater understanding of pulsar emission at all wavelengths, as well as to concrete insights into the physics of the magnetosphere.

  12. Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.

    1999-01-01

    Among the major discoveries made by the Mariner 10 mission to the inner planets was the existence of an intrinsic magnetic field at Mercury with a dipole moment of approx. 300 nT R(sup 3, sub M). This magnetic field is sufficient to stand off the solar wind at an altitude of about 1 R(sub M) (i.e. approx. 2439 km). Hence, Mercury possesses a 'magnetosphere' from which the so]ar wind plasma is largely excluded and within which the motion of charged particles is controlled by the planetary magnetic field. Despite its small size relative to the magnetospheres of the other planets, a Mercury orbiter mission is a high priority for the space physics community. The primary reason for this great interest is that Mercury unlike all the other planets visited thus far, lacks a significant atmosphere; only a vestigial exosphere is present. This results in a unique situation where the magnetosphere interacts directly with the outer layer of the planetary crust (i.e. the regolith). At all of the other planets the topmost regions of their atmospheres become ionized by solar radiation to form ionospheres. These planetary ionospheres then couple to electrodynamically to their magnetospheres or, in the case of the weakly magnetized Venus and Mars, directly to the solar wind. This magnetosphere-ionosphere coupling is mediated largely through field-aligned currents (FACs) flowing along the magnetic field lines linking the magnetosphere and the high-latitude ionosphere. Mercury is unique in that it is expected that FACS will be very short lived due to the low electrical conductivity of the regolith. Furthermore, at the earth it has been shown that the outflow of neutral atmospheric species to great altitudes is an important source of magnetospheric plasma (following ionization) whose composition may influence subsequent magnetotail dynamics. However, the dominant source of plasma for most of the terrestrial magnetosphere is the 'leakage'of solar wind across the magnetopause and more

  13. AGILE as a particle detector: Magnetospheric measurements of 10-100 MeV electrons in L shells less than 1.2

    NASA Astrophysics Data System (ADS)

    Argan, A.; Piano, G.; Tavani, M.; Trois, A.

    2016-04-01

    We study the capability of the AGILE gamma ray space mission in detecting magnetospheric particles (mostly electrons) in the energy range 10-100 MeV. Our measurements focus on the inner magnetic shells with L ≲ 1.2 in the magnetic equator. The instrument characteristics and a quasi-equatorial orbit of ˜500 km altitude make it possible to address several important properties of the particle populations in the inner magnetosphere. We review the on board trigger logic and study the acceptance of the AGILE instrument for particle detection. We find that the AGILE effective geometric factor (acceptance) is R≃50 cm2 sr for particle energies in the range 10-100 MeV. Particle event reconstruction allows to determine the particle pitch angle with the local magnetic field with good accuracy. We obtain the pitch angle distributions for both the AGILE "pointing" phase (July 2007 to October 2009) and the "spinning" phase (November 2009 to present). In spinning mode, the whole range (0-180 degrees) is accessible every 7 min. We find a pitch angle distribution of the "dumbbell" type with a prominent depression near α = 90° which is typical of wave-particle resonant scattering and precipitation in the inner magnetosphere. Most importantly, we show that AGILE is not affected by solar particle precipitation events in the magnetosphere. The satellite trajectory intersects magnetic shells in a quite narrow range (1.0 ≲ L ≲ 1.2); AGILE then has a high exposure to a magnetospheric region potentially rich of interesting phenomena. The large particle acceptance in the 10-100 MeV range, the pitch angle determination capability, the L shell exposure, and the solar-free background make AGILE a unique instrument for measuring steady and transient particle events in the inner magnetosphere.

  14. The equilibrium dayside magnetosphere

    NASA Technical Reports Server (NTRS)

    Zavriyev, Anton; Hasegawa, Akira

    1989-01-01

    A method is presented of computing the dayside global earth magnetic field which is in equilibrium with the plasma pressure, based on satellite observations at a local region of the magnetosphere. The method, which utilizes a perturbation around a dipole magnetic field, involves computation of the global plasma pressure profile based on the equatorial (anisotropic) pressure data, derivation of the current profile which satisfies the equilibrium condition, and computation of the magnetic field using the current profile and the boundary current produced by the solar wind. The method is applied for the Active Magnetospheric Particle Tracer Explorers data, and the result of the computation is found to compare reasonably well with the observed magnetic field profile near the geomagnetic equator.

  15. Medium-energy electrons and heavy ions in Jupiter's magnetosphere - Effects of lower hybrid wave-particle interactions

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1986-01-01

    A theory of medium-energy (about keV) electrons and heavy ions in Jupiter's magnetosphere is presented. Lower hybrid waves are generated by the combined effects of a ring instability of neutral wind pickup ions and the modified two-stream instability associated with transport of cool Iogenic plasma. The quasi-linear energy diffusion coefficient for lower hybrid wave-particle interactions is evaluated, and several solutions to the diffusion equation are given. Calculations based on measured wave properties show that the noise substantially modifies the particle distribution functions. The effects are to accelerate superthermal ions and electrons to keV energies and to thermalize the pickup ions on time scales comparable to the particle residence time. The S(2+)/S(+) ratio at medium energies is a measure of the relative contribution from Iogenic thermal plasma and neutral wind ions, and this important quantity should be determined from future measurements. The theory also predicts a preferential acceleration of heavy ions with an accleration time that scales inversely with the root of the ion mass. Electrons accelerated by the process contribute to further reionization of the neutral wind by electron impact, thus providing a possible confirmation of Alfven's critical velocity effect in the Jovian magnetosphere.

  16. Driving mechanisms of magnetospheric dynamics of planets and satellites

    NASA Astrophysics Data System (ADS)

    Nishida, Atsuhiro

    2004-01-01

    We review basic mechanisms of magnetospheric dynamics taking the cases of Ganymede, Mercury, and Jupiter. The topics include; (1) Whether or not possible effect of the intrinsic time variability of the reconnection rate can be seen in Ganymede's magnetosphere which is embedded in an almost fixed magnetic field of Jupiter. (2) How well the occurrence of reconnection is observationally founded for Mercury's magnetosphere. (3) In what ways various types of Jovian aurora are related to specific features of magnetospheric dynamics. (4) By what mechanisms solar wind influences the activity of the Jovian magnetosphere. (5) How the energetic particles are supplied to the boundary region of the Jovian magnetosphere and escape to the interplanetary space keeping high energies.

  17. Jupiter and Saturn Magnetospheric Active Archives at CDPP in support of the JUICE and Cassini missions

    NASA Astrophysics Data System (ADS)

    André, N.; Renard, B.; Cecconi, B.; Budnik, E.; Génot, V.; Jacquey, C.; Fedorov, A.; Hitier, R.; Bourrel, N.; Gangloff, M.; Pallier, E.; Bouchemit, M.; Besson, B.

    2012-09-01

    AMDA (Automated Multi-Dataset Analysis, http://cdpp-amda.cesr.fr/) is a web-based facility developed at CDPP Toulouse in France (http://cdpp.cesr.fr) for on line analysis of space physics data (heliosphere, magnetospheres, planetary environments) coming from either its local database or distant ones. We will report the status of our current technical and scientific efforts to integrate in the local database of AMDA Jupiter- and Saturn-related magnetospheric datasets from heterogeneous sources, including NASA/Planetary Data System (http://ppi.pds.nasa.gov/). We will also present our prototype Virtual Observatory activities to connect the AMDA tool to the IVOA Aladin astrophysical tool to enable pluridisciplinary studies of giant planet auroral emissions. This will be offered as a service of the scientific community in order to enhance the science return of the NASA/Cassini mission and in preparation of the JUICE mission.

  18. Space radiation analysis: Radiation effects and particle interaction outside the Earth's magnetosphere using GRAS and GEANT4

    NASA Astrophysics Data System (ADS)

    Martinez, Lisandro M.; Kingston, Jennifer

    2012-03-01

    In order to explore the Moon and Mars it is necessary to investigate the hazards due to the space environment and especially ionizing radiation. According to previous papers, much information has been presented in radiation analysis inside the Earth's magnetosphere, but much of this work was not directly relevant to the interplanetary medium. This work intends to explore the effect of radiation on humans inside structures such as the ISS and provide a detailed analysis of galactic cosmic rays (GCRs) and solar proton events (SPEs) using SPENVIS (Space Environment Effects and Information System) and CREME96 data files for particle flux outside the Earth's magnetosphere. The simulation was conducted using GRAS, a European Space Agency (ESA) software based on GEANT4. Dose and equivalent dose have been calculated as well as secondary particle effects and GCR energy spectrum. The calculated total dose effects and equivalent dose indicate the risk and effects that space radiation could have on the crew, these values are calculated using two different types of structures, the ISS and the TransHab modules. Final results indicate the amounts of radiation expected to be absorbed by the astronauts during long duration interplanetary flights; this denotes importance of radiation shielding and the use of proper materials to reduce the effects.

  19. The Energetic Particle Detector (EPD) Investigation and the Energetic Ion Spectrometer (EIS) for the Magnetospheric Multiscale (MMS) Mission

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.; Blake, J. B.; Baker, D. N.; Clemmons, J. H.; Reeves, G. D.; Spence, H. E.; Jaskulek, S. E.; Schlemm, C. E.; Brown, L. E.; Cooper, S. A.; Craft, J. V.; Fennell, J. F.; Gurnee, R. S.; Hammock, C. M.; Hayes, J. R.; Hill, P. A.; Ho, G. C.; Hutcheson, J. C.; Jacques, A. D.; Kerem, S.; Mitchell, D. G.; Nelson, K. S.; Paschalidis, N. P.; Rossano, E.; Stokes, M. R.; Westlake, J. H.

    2016-03-01

    The Energetic Particle Detector (EPD) Investigation is one of 5 fields-and-particles investigations on the Magnetospheric Multiscale (MMS) mission. MMS comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of the important physical process called magnetic reconnection using Earth's magnetosphere as a plasma laboratory. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly's Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions from a required low energy limit of 20 keV for protons and 45 keV for oxygen ions, up to >0.5 MeV (with capabilities to measure up to >1 MeV). FEEPS measures instantaneous all sky images of energetic electrons from 25 keV to >0.5 MeV, and also measures total ion energy distributions from 45 keV to >0.5 MeV to be used in conjunction with EIS to measure all sky ion distributions. In this report we describe the EPD investigation and the details of the EIS sensor. Specifically we describe EPD-level science objectives, the science and measurement requirements, and the challenges that the EPD team had in meeting these requirements. Here we also describe the design and operation of the EIS instruments, their calibrated performances, and the EIS in-flight and ground operations. Blake et al. (The Flys Eye Energetic Particle Spectrometer (FEEPS) contribution to the Energetic Particle Detector (EPD) investigation of the Magnetospheric Magnetoscale (MMS) Mission, this issue) describe the design and operation of the FEEPS instruments, their calibrated performances, and the FEEPS in-flight and ground operations. The MMS spacecraft will launch in early 2015, and over its 2-year mission will provide comprehensive measurements of magnetic reconnection at Earth

  20. Postmidnight chorus - A substorm phenomenon. [outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Tsurutani, B. T.; Smith, E. J.

    1974-01-01

    The ELF emissions were detected in the midnight sector of the magnetosphere in conjunction with magnetospheric substorms. The emissions were observed at local midnight and early morning hours and are accordingly called 'post-midnight chorus.' The characteristics of these emissions such as their frequency time structure, emission frequency with respect to the local equatorial electron gyrofrequency, intensity-time variation, and the average intensity were investigated. The occurrence of the chorus in the nightside magnetosphere was investigated as a function of local time, L shell, magnetic latitude, and substorm activity, and the results of this analysis are presented. Specific features of postmidnight chorus are discussed in the context of possible wave-particle interactions occurring during magnetospheric substorms.

  1. The magnetosphere of Saturn

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.

    1982-01-01

    Information about the magnetosphere of Saturn is provided: the magnetic dipole moment is axisymmetric, the bow shock stand-off distance is about 22 R sub S. The satellites Titan, Dione, and Tethys are probably the primary sources of magnetospheric plasma. Outside of approx. 4 R sub S, energetic particles are energized by diffusing inward while conserving their first and second adiabatic invariants. Particles are lost by satellite sweep-out, absorption byt the E ring and probably also by plasma interactions. The inner magnetosphere is characterized.

  2. Visualization of ion cyclotron wave and particle interactions in the inner magnetosphere via THEMIS-ASI observations

    NASA Astrophysics Data System (ADS)

    Sakaguchi, K.; Miyoshi, Y.; Spanswick, E.; Donovan, E.; Mann, I. R.; Jordanova, V.; Shiokawa, K.; Connors, M.; Green, J. C.

    2012-10-01

    Interaction with EMIC (electromagnetic ion cyclotron) waves is thought to be a key component contributing to the very rapid loss of both ring current and radiation belt particles into the atmosphere. Estimated loss rates are heavily dependent on the assumed spatial distribution of the EMIC wave. Statistical maps of the spatial distribution have been produced using in-situ satellite data. However, with limited satellite data it is impossible to deduce the true spatial distribution. In this study, we present ground-based observations using all-sky imager and search coil magnetometer networks, which provide the large-scale distribution and motion of the EMIC wave-particle interaction regions. We observed several spots of isolated proton auroras simultaneously with Pc1/EMIC waves at subauroral latitudes during the expansion phase of a storm-time substorm on 9 March 2008. The isolated auroras were distributed over ∼4-hours MLT preceding midnight. The POES-17 satellite confirmed enhancements of 30-keV proton precipitations over the isolated auroras. The equatorward motion of the auroras and frequency drift of the wave were consistent with the plasmasphere eroding due to a polar cap potential enhancement modeled by a numerical simulation. We also found that relativistic electron precipitation was not always associated with the isolated aurora, depending strongly on the plasma density profile near the plasmapause. This study shows that the specific distribution of ring current proton precipitation can be visualized through the ground network observations. By combining with upcoming inner-magnetosphere satellite missions, these remote-sensing observations are very important for quantitative understanding of the particle loss in the inner magnetosphere.

  3. Effect on GLE Occurrence Distribution: Possible Action on Active Region by Earth and Jupiter Magnetospheres through Cosmic Ray Deflection

    NASA Astrophysics Data System (ADS)

    Del Pozo Garcia, Eduardo

    Eduardo del Pozo Garcia Geophysics and Astronomy Institute Havana, Cuba pozo@iga.cu Following Perez- Peraza and collaborators works on GLE prediction on basis to Cosmic Ray periodicities and cycles, in particular with 1,2 year cycle, effect prognosis of GLE occurrence was determine, I present here a possible interpretation of their results. Here I present the time distribution of the observed GLE in respect to each GLE nearly Sun-Earth-Jupiter alignment time. At the histogram the X axis cero is the alignment time. These alignments take place cyclically every 1,1 year. The histogram shows a modulation-like GLE distribution. The occurrence increments are near the alignment time and, about 125 days before and after the alignment time. Besides, a work hypothesis is proposed: “The Jupiter and Earth magnetospheres must deflect cosmic rays and, at some Jupiter and Earth positions according the current interplanetary magnetic field, may be favorable to increase the energetic particle flux over current Sun active regions, giving place to a modulation-like GLE distribution. Also, by the cosmic rays action some particle flux increase over active regions may come from radiation belts” This effect means that, during solar activity this is a factor that contributes to: - An accumulative activity increase of sunspot groups and their magnetic configuration complexity - Eventually, over complex active region some increase of high energy particle flux help to trigger GLE, or intensify solar proton events in progress, and become a GLE. This effect is taken into account for GLE prediction.

  4. Siple station experiments on wave-particle interactions in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Helliwell, R. A.

    1979-01-01

    Natural and controlled whistler-mode signals have been used to study nonlinear mechanisms of wave growth and wave-wave interactions (WWI) in the magnetosphere; three general classes of WWI (triggering, suppression, and entrainment) are identified and interpreted in terms of a model based on cyclotron resonance interaction. This model is also used to estimate the wave field intensity associated with different types of WWI. A new type of triggered emission, the band-limited impulse (BLI) is interpreted in terms of the switching of phase-bunched currents. In addition, an experiment to find a threshold for the excitation of the coherent wave instability is discussed, and observed VLF wave-induced transient bursts of X-rays, light and E-region ionization enhancements are considered with regard to a step function wave interacting with all resonant electrons in a given energy range.

  5. Particle precipitation due to ion-cyclotron instability in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Yahnin, Alexander

    Electromagnetic ion-cyclotron (EMIC) waves in the near-Earth equatorial magnetosphere effectively scatter energetic ions into the loss cone. As consequence, localized precipitation of energetic protons (LPEP) within the anisotropy zone is observed by low-orbiting satellites, like NOAA POES. Strong LPEP produces sub-oval proton auroras, which provide a two-dimensional image of the source region on the ionospheric screen. Here, we present some multipoint conjugate measurements confirming the relationship between LPEP and EMIC waves. Also, a conjugacy of LPEP and plasmapause structures is proved. In addition to LPEP, a wide (both in latitude and longitude) area of proton precipitation is often observed outside the plasmapause at sub-oval latitudes on the dayside. Both the case and statistical studies confirm that this dayside proton precipitation correlates with EMIC waves. Development of the ion-cyclotron instability on the dayside is evidently due to the enhanced transverse anisotropy of proton fluxes, which, in turn, is the result of the drift shell splitting. The anisotropy is “modulated” by the solar wind dynamic pressure. During magnetosphere compressions the precipitating proton flux increases, and flashes of the sub-oval proton aurora can be observed the dayside. It is suggested that EMIC waves also scatter relativistic electrons. Using the proton precipitation within the anisotropy zone as an indicator of the ion-cyclotron instability we performed a search of simultaneous relativistic electron precipitation (REP). We found that only 10 percent of REP events could be considered as potentially related to EMIC waves. These “EMIC wave related REP events” are observed only in the evening sector in connection with the plasmaspheric plume.

  6. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  7. Modeling Magnetospheric Sources

    NASA Technical Reports Server (NTRS)

    Walker, Raymond J.; Ashour-Abdalla, Maha; Ogino, Tatsuki; Peroomian, Vahe; Richard, Robert L.

    2001-01-01

    We have used global magnetohydrodynamic, simulations of the interaction between the solar wind and magnetosphere together with single particle trajectory calculations to investigate the sources of plasma entering the magnetosphere. In all of our calculations solar wind plasma primarily enters the magnetosphere when the field line on which it is convecting reconnects. When the interplanetary magnetic field has a northward component the reconnection is in the polar cusp region. In the simulations plasma in the low latitude boundary layer (LLBL) can be on either open or closed field lines. Open field lines occur when the high latitude reconnection occurs in only one cusp. In the MHD calculations the ionosphere does not contribute significantly to the LLBL for northward IMF. The particle trajectory calculations show that ions preferentially enter in the cusp region where they can be accelerated by non-adiabatic motion across the high latitude electric field. For southward IMF in the MHD simulations the plasma in the middle and inner magnetosphere comes from the inner (ionospheric) boundary of the simulation. Solar wind plasma on open field lines is confined to high latitudes and exits the tailward boundary of the simulation without reaching the plasma sheet. The LLBL is populated by both ionospheric and solar wind plasma. When the particle trajectories are included solar wind ions can enter the middle magnetosphere. We have used both the MHD simulations and the particle calculations to estimate source rates for the magnetosphere which are consistent with those inferred from observations.

  8. Dipolarizing flux bundles in the cis-geosynchronous magnetosphere: Relationship between electric fields and energetic particle injections

    NASA Astrophysics Data System (ADS)

    Liu, Jiang; Angelopoulos, V.; Zhang, Xiao-Jia; Turner, D. L.; Gabrielse, C.; Runov, A.; Li, Jinxing; Funsten, H. O.; Spence, H. E.

    2016-02-01

    Dipolarizing flux bundles (DFBs) are small flux tubes (typically <3 RE in XGSM and YGSM) in the nightside magnetosphere that have magnetic field more dipolar than the background. Although DFBs are known to accelerate particles, creating energetic particle injections outside geosynchronous orbit (trans-GEO), the nature of the acceleration mechanism and the importance of DFBs in generating injections inside geosynchronous orbit (cis-GEO) are unclear. Our statistical study of cis-GEO DFBs using data from the Van Allen Probes reveals that just like trans-GEO DFBs, cis-GEO DFBs occur most often in the premidnight sector, but their occurrence rate is ~1/3 that of trans-GEO DFBs. Half the cis-GEO DFBs are accompanied by an energetic particle injection and have an electric field 3 times stronger than that of the injectionless half. All DFB injections are dispersionless within the temporal resolution considered (11 s). Our findings suggest that these injections are ushered or produced locally by the DFB, and the DFB's strong electric field is an important aspect of the injection generation mechanism.

  9. Particle Acceleration in Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Miller, James A.

    1997-01-01

    The high efficiency of energy generation inferred from radio observations of quasars and X-ray observations of Seyfert active galactic nuclei (AGNs) is apparently achieved only by the gravitational conversion of the rest mass energy of accreting matter onto supermassive black holes. Evidence for the acceleration of particles to high energies by a central engine is also inferred from observations of apparent superluminal motion in flat spectrum, core-dominated radio sources. This phenomenon is widely attributed to the ejection of relativistic bulk plasma from the nuclei of active galaxies, and accounts for the existence of large scale radio jets and lobes at large distances from the central regions of radio galaxies. Reports of radio jets and superluminal motion from galactic black hole candidate X-ray sources indicate that similar processes are operating in these sources. Observations of luminous, rapidly variable high-energy radiation from active galactic nuclei (AGNs) with the Compton Gamma Ray Observatory show directly that particles are accelerated to high energies in a compact environment. The mechanisms which transform the gravitational potential energy of the infalling matter into nonthermal particle energy in galactic black hole candidates and AGNs are not conclusively identified, although several have been proposed. These include direct acceleration by static electric fields (resulting from, for example, magnetic reconnection), shock acceleration, and energy extraction from the rotational energy of Kerr black holes. The dominant acceleration mechanism(s) operating in the black hole environment can only be determined, of course, by a comparison of model predictions with observations. The purpose of the work proposed for this grant was to investigate stochastic particle acceleration through resonant interactions with plasma waves that populate the magnetosphere surrounding an accreting black hole. Stochastic acceleration has been successfully applied to the

  10. Principal component analysis of Birkeland currents determined by the Active Magnetosphere and Planetary Electrodynamics Response Experiment

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Carter, J. A.; Korth, H.; Anderson, B. J.

    2015-12-01

    Principal component analysis is performed on Birkeland or field-aligned current (FAC) measurements from the Active Magnetosphere and Planetary Electrodynamics Response Experiment. Principal component analysis (PCA) identifies the patterns in the FACs that respond coherently to different aspects of geomagnetic activity. The regions 1 and 2 current system is shown to be the most reproducible feature of the currents, followed by cusp currents associated with magnetic tension forces on newly reconnected field lines. The cusp currents are strongly modulated by season, indicating that their strength is regulated by the ionospheric conductance at the foot of the field lines. PCA does not identify a pattern that is clearly characteristic of a substorm current wedge. Rather, a superposed epoch analysis of the currents associated with substorms demonstrates that there is not a single mode of response, but a complicated and subtle mixture of different patterns.

  11. Global-mode Pc 5 pulsations: Ground distribution and correlation with energetic particles in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Yousif Suliman, M. E.; Yumoto, K.; Yoshikawa, A.; Uozumi, T.; Kawano, H.; Abe, S.; Cardinal, M. G.; Winkler, L. I.

    2012-12-01

    A sound history has been well known for decades concerning the studies of the correlations between high energetic electrons in the radiation belts and ULF magnetic pulsations, especially in the Pc 5 range in recent papers. Still, there remain open questions on which many researches are currently working. One of such questions is: Is there some kind of global-mode Pc 5 pulsations which enhances the density of high energetic particles in the inner magnetosphere? This question has motivated this study on the existence of such a global mode of Pc 5 pulsations at mid-latitudes. In this study we have identified global-mode Pc 5 geomagnetic pulsations as those simultaneously observed at three mid-latitude MAGDAS/CPMN ground stations separated by ~120deg in longitude from each other, and studied their features and their correlations with solar wind parameters and high energetic particles in the radiation belts. The specific selection criteria of the global-mode Pc 5 pulsation is as follows: Each Pc 5 event at each station must have large amplitudes (larger than 0.4nT at L<2, larger than 1.0nT at L>3) and long life periods (at least two hours). (Such criteria are relatively strict comparing with past studies but suitable for continuous monitoring of Pc 5 pulsations.) Furthermore, each event must be simultaneously observed at all the three ground stations. Detailed nature of thus identified global Pc 5 pulsations will be discussed in the presentation.

  12. Onset of magnetospheric substorms.

    NASA Technical Reports Server (NTRS)

    Tsurutani, B.; Bogott, F.

    1972-01-01

    An examination of the onset of magnetospheric substorms is made by using ATS 5 energetic particles, conjugate balloon X rays and electric fields, all-sky camera photographs, and auroral-zone magnetograms. It is shown that plasma injection to ATS distances, conjugate 1- to 10-keV auroral particle precipitation, energetic electron precipitation, and enhancements of westward magnetospheric electric-field component all occur with the star of slowly developing negative magnetic bays. No trapped or precipitating energetic-particle features are seen at ATS 5 when later sharp negative magnetic-bay onsets occur at Churchill or Great Whale River.

  13. Solar Wind-Magnetosphere Coupling Influences on Pseudo-Breakup Activity

    NASA Technical Reports Server (NTRS)

    Fillingim, M. O.; Brittnacher, M.; Parks, G. K.; Germany, G. A.; Spann, J. F.

    1998-01-01

    Pseudo-breakups are brief, localized aurora[ arc brightening, which do not lead to a global expansion, are historically observed during the growth phase of substorms. Previous studies have demonstrated that phenomenologically there is very little difference between substorm onsets and pseudo-breakups except for the degree of localization and the absence of a global expansion phase. A key open question is what physical mechanism prevents a pseudo-breakup form expanding globally. Using Polar Ultraviolet Imager (UVI) images, we identify periods of pseudo-breakup activity. Foe the data analyzed we find that most pseudo-breakups occur near local midnight, between magnetic local times of 21 and 03, at magnetic latitudes near 70 degrees, through this value may change by several degrees. While often discussed in the context of substorm growth phase events, pseudo-breakups are also shown to occur during prolonged relatively inactive periods. These quiet time pseudo-breakups can occur over a period of several hours without the development of a significant substorm for at least an hour after pseudo-breakup activity stops. In an attempt to understand the cause of quiet time pseudo-breakups, we compute the epsilon parameter as a measure of the efficiency of solar wind-magnetosphere coupling. It is noted that quiet time pseudo-breakups occur typically when epsilon is low; less than about 50 GW. We suggest that quiet time pseudo-breakups are driven by relatively small amounts of energy transferred to the magnetosphere by the solar wind insufficient to initiate a substorm expansion onset.

  14. Saturn's outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.; Behannon, K. W.; Carbary, J. F.; Eviatar, A.; Lepping, R. P.; Siscoe, G. L.

    1983-01-01

    Similarities between the Saturnian and terrestrial outer magnetosphere are examined. Saturn, like Earth, has a fully developed magnetic tail, 80 to 100 RS in diameter. One major difference between the two outer magnetospheres is the hydrogen and nitrogen torus produced by Titan. This plasma is, in general, convected in the corotation direction at nearly the rigid corotation speed. Energies of magnetospheric particles extend to above 500 keV. In contrast, interplanetary protons and ions above 2 MeV have free access to the outer magnetosphere to distances well below the Stormer cutoff. This access presumably occurs through the magnetotail. In addition to the H+, H2+, and H3+ ions primarily of local origin, energetic He, C, N, and O ions are found with solar composition. Their flux can be substantially enhanced over that of interplanetary ions at energies of 0.2 to 0.4 MeV/nuc.

  15. Magnetospheric Substorm Electrodynamics

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1998-01-01

    It was proposed that the expansion phase of substorms results from a reduction in the large-scale electric field imparted to the magnetosphere from the solar wind, following a greater than or equal to 30 min growth phase due to an enhancement in this electric field. The reduction in the electric field is assumed to propagate anti-sunward within the magnetosphere. Triggering by a reduction in the electric field is suggested by the observation that substorms are often triggered by northward turning of the interplanetary magnetic field (IMF). However, under the theory presented here, substorms may be triggered by anything that causes an electric field reduction such as a reduction in the magnitude of the y-component of the IMF. A reduction in the large-scale electric field disrupts both the inward motion and energization of plasma sheet particles that occurs during the growth phase. It is suggested here that this can lead to formation of the expansion-phase current wedge and active aurora. The current wedge results from the magnetic drift of ions, which has a speed proportional to particle energy, and a large azimuthal gradient in mean particle energy that is expected to develop in the vicinity of magnetic midnight during the growth phase. Current wedge formation will most likely be initiated near the radial distance (approx. 6- 10 R(sub E)) of the peak in the growth-phase plasma pressure distribution, and then propagate tailward from that region. Order-of-magnitude calculations show that the above proposal can account for the rapid development of the expansion phase relative to the growth phase, the magnitude of the reduction in the cross-tail current within the current wedge, the speeds of tailward and westward expansion of the current reduction region, the speeds of poleward and westward motion of active aurora in the ionosphere, and the magnitude of wedge field-aligned currents that connect the ionospheric region of active auroral to the divergent cross

  16. Particle resuspension via human activity

    NASA Astrophysics Data System (ADS)

    Qian, Jing

    This dissertation consists of three correlated parts that are related to particle resuspension from floorings in indoor environment. The term resuspension in this dissertation refers the re-entrainment of deposited particles into atmosphere via mechanic disturbances by human activity indoors, except where it is specified. The first part reviews the literature related to particle resuspension. Fundamental concepts and kinetics of resuspension of particles were extracted from previous studies. Suggestions for future research on indoor particle resuspension have been given based on the literature reviews and the findings of part 2 and part 3. The second part involved 54 resuspension experiments conducted in a room-scale environmental chamber. Three floorings types and two ventilation configurations were tested. Air exchange rate were fixed during the experiments, and the temperature/RH were monitored. The airborne particle concentration was measured by an array of optical particle counters (OPCs) in the chamber. Resuspension rates were estimated in size ranges of 0.8--1, 1.0--2.0, 2.0--5.0, and 5.0--10 mum ranging from 10-5--10 -2 hr-1, with higher resuspension rates associated with larger particles. Resuspension via walking activity varied from experiment to experiment. A "heavy and fast" walking style was associated with a higher resuspension rate than a less active style. Given the same floor loading of the test particles, resuspension rates for the carpeted floor were on the same order of magnitude but significantly higher than those for the hard floor. In the third part, an image analysis method (IAM) was adapted to characterize the particle distribution on fabric floorings. The IAM results showed the variability of particles loading on various carpets. The dust particles on fibers from ten carpets vary in sizes. The normal dust loading varies from house to house from 3.6x106 particles/cm2 to 8.2x106 particles/cm2. The dust particle number distribution for size

  17. Pamela’s Measurements of Magnetospheric Effects On High Energy Solar Particles

    NASA Astrophysics Data System (ADS)

    Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bravar, U.; Bruno, A.; Cafagna, F.; Campana, D.; Carbone, R.; Carlson, P.; Casolino, M.; Castellini, G.; Christian, E. R.; De Donato, C.; de Nolfo, G. A.; De Santis, C.; De Simone, N.; Di Felice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Lee, M.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergé, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Ryan, J. M.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stochaj, S.; Stozhkov, Y. I.; Thakur, N.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.

    2015-03-01

    The nature of particle acceleration at the Sun, whether through flare reconnection processes or through shocks driven by coronal mass ejections, is still under scrutiny despite decades of research. The measured properties of solar energetic particles (SEPs) have long been modeled in different particle-acceleration scenarios. The challenge has been to disentangle the effects of transport from those of acceleration. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument enables unique observations of SEPs including the composition and angular distribution of the particles about the magnetic field, i.e., pitch angle distribution, over a broad energy range (>80 MeV)—bridging a critical gap between space-based and ground-based measurements. We present high-energy SEP data from PAMELA acquired during the 2012 May 17 SEP event. These data exhibit differential anisotropies and thus transport features over the instrument rigidity range. SEP protons exhibit two distinct pitch angle distributions: a low-energy population that extends to 90° and a population that is beamed at high energies (>1 GeV), consistent with neutron monitor measurements. To explain a low-energy SEP population that exhibits significant scattering or redistribution accompanied by a high-energy population that reaches the Earth relatively unaffected by dispersive transport effects, we postulate that the scattering or redistribution takes place locally. We believe that these are the first comprehensive measurements of the effects of solar energetic particle transport in the Earth’s magnetosheath.

  18. Upstream Structures and Their Effects on the Magnetosphere

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.

    2011-01-01

    Kinetic processes within the Earth's foreshock generate a profusion of plasma and magnetic field structures with sizes and durations ranging from the microscale (e.g. SLAMs, solitons, and density holes) to the mesoscale (e.g. foreshock cavities or boundaries, hot flow anomalies, and bubbles). Swept into the bow shock by the solar wind flow, the perturbations associated with these features batter the magnetosphere, driving a wide variety of magnetospheric effects, including large amplitude magnetopause motion, bursty reconnection and the generation of flux transfer events, enhanced pulsation activity within the magnetosphere, diffusion and energization of radiation belt particles, enhanced particle precipitation resulting in dayside aurora and riometer absorption, and the generation of field-aligned currents and magnetic impulse events in high-latitude ground magnetometers. This talk reviews the ever growing menagery of structures observed upstream from the bow shock, examines their possible interrelationships, and considers their magnetospheric consequences.

  19. The AMPTE program's contribution to studies of the solar wind-magnetosphere-ionosphere interaction

    SciTech Connect

    Sibeck, D.G. )

    1990-12-01

    The Active Magnetospheric Particle Tracer Explorers (AMPTE) program provided important information on the behavior of clouds of plasma artificially injected into the solar wind and the earth's magnetosphere. Now that the releases are over, data from the satellites are being analyzed to investigate the processes by which the ambient solar wind mass, momentum, and energy are transferred to the magnetosphere. Work in progress at APL indicates that the solar wind is much more inhomogeneous than previously believed, that the solar wind constantly buffets the magnetosphere, and that ground observers may remotely sense these interactions as geomagnetic pulsations. 8 refs.

  20. Magnetospheric Multiscale (MMS) Mission Observations of Energetic Particle Dynamics and Structures Prior To and During Its First Encounters with the Reconnection-Rich Regions of Earth's Magnetopause

    NASA Astrophysics Data System (ADS)

    Mauk, B.; Westlake, J. H.; Cohen, I. J.; Blake, J. B.; Fennell, J. F.; Baker, D. N.; Jaynes, A. N.; Spence, H. E.; Burch, J. L.; Torbert, R. B.; Moore, T. E.; Giles, B. L.; Pollock, C. J.; Fuselier, S. A.; Nakamura, R.; Reeves, G. D.

    2015-12-01

    The Magnetospheric Multiscale (MMS) mission, launched on 13 March 2015, comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of magnetic reconnection using Earth's magnetosphere as a plasma laboratory. The Energetic Particle Detector (EPD) Investigation on MMS is one of several fields-and-particles investigations. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly's Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions for protons from < 20 keV, and oxygen from 45 keV, up to > 1 MeV. FEEPS measures instantaneous ( 1/3 s) all sky images of energetic electrons from 25 keV to > 0.6 MeV and also measures total ion energy distributions from 45 keV to > 0.5 MeV to be used in conjunction with EIS to measure all-sky ion distributions. During the preparation stages for the prime mission (prior to 1 September 2015), with a 1.2 x 12 RE orbit precessing across the root of the magnetotail, EPD observed energetic particle responses to depolarization fronts and related particle injection features, ion composition and flow dynamics associated with injections, the dynamic formation of trapping-boundary-like features at intermediate magnetic latitudes, striking electron beam and butterfly distributions likely providing precursors to observations of the magnetopause-magnetosphere interface, and intense modulations in association ULF waves. In this overview presentation, we use some of these observations to document the promise that the EPD investigation holds for contributing to the resolution of reconnection-induced particle acceleration and structuring. We then show the early-mission energetic particle structures and dynamics observed at the magnetopause and in association with

  1. Magnetosphere of Uranus

    SciTech Connect

    Ness, N.F.

    1986-12-01

    The magnetosphere and magnetic field of Uranus are analyzed using Voyager 2 data. It is observed that the magnetic axis of Uranus is tilted 60 deg from its rotation axis; the magnetic dipole center is displaced almost 7700 km from the center of the planet; the magnetic field intensity varies over its surface between 24,000-69,000 gammas; and the rotation rate of the planet is 17.24 hours. The dynamo generation of the planetary magnetic field is examined. Consideration is given to the auroral activity, magnetic tails, moons, and radiation belts of charged particles of Uranus. The significance of the large tilt and offset magnetic axis for the interior of Uranus is discussed.

  2. Solar Cycle Dynamics of Solar, Magnetospheric, and Heliospheric Particles, and Long-Term Atmospheric Coupling: SAMPEX

    NASA Technical Reports Server (NTRS)

    Mason, G. M.; Blake, J. B.; Mewaldt, R. A.; Stone, E. C.; Baker, D. N.

    1998-01-01

    This report summarizes science analysis activities by the SAMPEX mission science team during the period during the period July 1, 1997 through July 1, 1998. Bibliographic entries for 1997 and 1998 to date (July 1998) are included. The SAMPEX science team was extremely active, with 20 articles published or submitted to refereed journals, 11 papers published in their entirety in Conference Proceedings, and 49 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings, as well as other activities of the team.

  3. Solar Cycle Dynamics of Solar, Magnetospheric, and Heliospheric Particles, and Long-Term Atmospheric Coupling: SAMPEX

    NASA Technical Reports Server (NTRS)

    Mason, G. M.; Blake, J. B.; Mewaldt, R. A.; Stone, E. C.; Baker, D. N.; vonRosenvinge, T. T.; Callis, L. B.; Hamilton, D. C.; Klecker, B.; Hovestadt, D.; Scholer, M.

    1997-01-01

    This report summarizes science analysis activities by the SAMPEX mission science team during the period during the period July 1, 1997 through July 1, 1997. Bibliographic entries for 1996 and 1997 to date (July 1997) are included. The SAMPEX science team was extremely active, with 27 articles published or submitted to refereed journals, 17 papers published in their entirety in Conference Proceedings, and 74 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings, as well as other activities of the team.

  4. Solar Cycle Dynamics of Solar, Magnetospheric, and Heliospheric Particles, and Long-Term Atmospheric Coupling: SAMPEX

    NASA Technical Reports Server (NTRS)

    Mason, G. M.; Blake, J. B.; Mazur, J. E.; Mewaldt, R. A.; Stone, E. C.; Baker, D. N.; vonRosenvinge, T. T.; Callis, L. B.; Klecker, B.; Hovestadt, D.; Scholer, M.

    2000-01-01

    This final technical report summarizes science analysis activities by the SAMPEX mission science team during the period July 1, 1995 through September 30, 2000. Bibliographic entries for 1995 to date (October 2000) are included. The SAMPEX science team was extremely active, with 72 articles published or submitted to referred journals, 38 papers published in their entirety in Conference Proceedings, and 260 contributed papers, seminars, and miscellaneous presentations. The bibliography at the end of this report constitutes the primary description of the research activity. Science highlights are given under the major activity headings, as well as other activities of the team. One Ph.D. student, Mr. Daniel Williams, completed his thesis at California Institute of Technology based on data from the MAST instrument.

  5. Active experiments using rocket-borne shaped charge barium releases. [solar-terrestrial magnetospheric physics

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Davis, T. N.

    1980-01-01

    A reliable payload system and scaled down shaped charges were developed for carrying out experiments in solar-terrestrial magnetospheric physics. Four Nike-Tomahawk flights with apogees near 450 km were conducted to investigate magnetospheric electric fields, and two Taurus-Tomahawk rockets were flown in experiments on the auroral acceleration process in discrete auroras. In addition, a radial shaped charge was designed for plasma perturbation experiments.

  6. Active particles on curved surfaces

    NASA Astrophysics Data System (ADS)

    Fily, Yaouen; Baskaran, Aparna; Hagan, Michael

    Active systems have proved to be very sensitive to the geometry of their environment. This is often achieved by spending significant time at the boundary, probing its shape by gliding along it. I will discuss coarse graining the microscopic dynamics of self-propelled particles on a general curved surface to predict the way the density profile on the surface depends on its geometry. Beyond confined active particles, this formalism is a natural starting point to study objects that cannot leave the boundary at all, such as cells crawling on a curved substrate, animals running on uneven ground, or active colloids trapped at an interface.

  7. Nonlinear Evolution of Ion Acoustic Solitary Waves in Earth's Magnetosphere: Fluid and Particle-In-Cell Simulations

    NASA Astrophysics Data System (ADS)

    Kakad, A.; Kakad, B. A.; Omura, Y.

    2014-12-01

    In recent spacecraft observations, coherent electrostatic solitary wave (ESWs) structures are observed in various regions of the Earth's magnetosphere. Over the years, many researchers have attempted to model these observations in terms of electron/ion acoustic solitary waves by using nonlinear fluid theory/simulations. The ESW structures predicted by fluid models can be inadequate due to its inability in handling kinetic effects. To provide clear view on the application of the fluid and kinetic treatments in modeling the ESWs, we perform both fluid and particle-in-cell (PIC) simulations of ion acoustic solitary waves (IASWs) and estimate the quantitative differences in their characteristics like speed, amplitude, and width. It is noted that a long time evolution of Gaussian type perturbations in the equilibrium electron and ion densities generated the nonlinear IASW structures in both fluid and PIC simulations. The IASW structures represent vortices of trapped electrons in PIC simulations. We find that the number of trapped electrons in the wave potential is higher for the large amplitude IASW, which are generated by large-amplitude initial density perturbation (IDP). The present fluid and PIC simulation results are in close agreement for small amplitude IDPs, whereas for large IDPs they show discrepancy in the amplitude, width, and speed of the IASW, which is attributed to negligence of kinetic effects in the former approach. The speed of IASW in the fluid simulations increases with the increase of IASW amplitude, while the reverse tendency is seen in the PIC simulation. The present study suggests that the fluid treatment is appropriate to model the IASW observations when the magnitude of phase velocity of IASW is less than the ion acoustic (IA) speed obtained from their linear dispersion relation, whereas when it exceeds IA speed, it is necessary to include the kinetic effects in the model.

  8. The temporal evolution of electron distributions and associated wave activity following substorm injections in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Meredith, Nigel P.; Horne, Richard B.; Johnstone, Alan D.; Anderson, Roger R.

    2000-06-01

    The temporal evolution of electron distributions and associated wave activity following substorm injections in the inner magnetosphere are investigated using data from the CRRES satellite. Equatorial electron distributions and concomitant wave spectra outside the plasmapause on the nightside of the Earth are studied as a function of time since injection determined from the auroral-electrojet index (AE). The electron cyclotron harmonic (ECH) wave amplitudes are shown to be very sensitive to small modeling errors in the location of the magnetic equator. They are best understood at the ECH equator, defined by the local maximum in the ECH wave activity in the vicinity of the nominal magnetic equator, suggesting that the ECH equator is a better measure of the location of the true equator. Strong ECH and whistler mode wave amplitudes are associated with the injected distributions and at the ECH equator, in the region 6.0<=L<7.0, exponential fits reveal wave amplitude decay time constants of 6.3+/-1.2 and 4.6+/-0.7 hours, respectively. Pancake electron distributions are seen to develop from injected distributions that are nearly isotropic in velocity space and, in this region, are seen to form on a similar timescale of approximately 4 hours suggesting that both wave types are involved in their production. The timescale for pancake production and wave decay is comparable with the average time interval between substorm events so that the wave-particle interactions are almost continually present in this region leading to a continual supply of electrons to power the diffuse aurora. In the region 3.8<=L<6.0 the timescale for wave decay at the ECH equator is 2.3+/-0.6 and 1.1+/-0.2 hours for ECH waves and whistler mode waves respectively, although the pancakes in this region show no clear evolution as a function of time.

  9. Magnetospheric multiprobes: Investigations and instrumentation

    NASA Technical Reports Server (NTRS)

    Burch, J. L.; Chappell, C. R.; Fields, S. A.; Falthammar, C. G.; Winningham, J. D.; Hanson, W. B.; Heelis, R. A.; Heikkila, W. J.; Sugira, M.; Farthing, W. H.

    1980-01-01

    The multiprobe scientific objectives are to: (1) determine the spatial structure of plasma phenomena such as the aurora, convection reversals, and ion troughs; (2) separate spatial and temporal variations in these phenomena; (3) determine field aligned current densities; (4) perform multiple point analysis of particle beams, wave fields, and plasma clouds that are injected into the ionosphere and magnetosphere by Spacelab active experiment facilities. Trade studies described include: instrument accommodations, power, attitude determination, electric field antennas, storage and ejection, thermal control, tracking communications, command and data management, payload and mission specialist support, functional objectives, and orbital analysis.

  10. Ionosphere-magnetosphere coupling

    NASA Technical Reports Server (NTRS)

    Kaufmann, Richard L.

    1994-01-01

    Principal results are presented for the four papers that were supported from this grant. These papers include: 'Mapping and Energization in the Magnetotail. 1. Magnetospheric Boundaries; 'Mapping and Energization in the Magnetotail. 2. Particle Acceleration'; 'Cross-Tail Current: Resonant Orbits'; and 'Cross-Tail Current, Field-Aligned Current, and B(sub y)'.

  11. Proton velocity ring-driven instabilities in the inner magnetosphere: Linear theory and particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Min, Kyungguk; Liu, Kaijun

    2016-01-01

    Linear dispersion theory and electromagnetic particle-in-cell (PIC) simulations are used to investigate linear growth and nonlinear saturation of the proton velocity ring-driven instabilities, namely, ion Bernstein instability and Alfvén-cyclotron instability, which lead to fast magnetosonic waves and electromagnetic ion cyclotron waves in the inner magnetosphere, respectively. The proton velocity distribution is assumed to consist of 10% of a ring distribution and 90% of a low-temperature Maxwellian background. Here two cases with ring speeds vr/vA=1 and 2 (vA is the Alfvén speed) are examined in detail. For the two cases, linear theory predicts that the maximum growth rate γm of the Bernstein instability is 0.16Ωp and 0.19Ωp, respectively, and γm of the Alfvén-cyclotron instability is 0.045Ωp and 0.15Ωp, respectively, where Ωp is the proton cyclotron frequency. Two-dimensional PIC simulations are carried out for the two cases to examine the instability development and the corresponding evolution of the particle distributions. Initially, Bernstein waves develop and saturate with strong electrostatic fluctuations. Subsequently, electromagnetic Alfvén-cyclotron waves grow and saturate. Despite their smaller growth rate, the saturation levels of the Alfvén-cyclotron waves for both cases are larger than those of the Bernstein waves. Resonant interactions with the Bernstein waves lead to scattering of ring protons predominantly along the perpendicular velocity component (toward both decreasing and, at a lesser extent, increasing speeds) without substantial change of either the parallel temperature or the temperature anisotropy. Consequently, the Alfvén-cyclotron instability can still grow. Furthermore, the free energy resulting from the pitch angle scattering by the Alfvén-cyclotron waves is larger than the free energy resulting from the perpendicular energy scattering, thereby leading to the larger saturation level of the Alfvén-cyclotron waves.

  12. MESSENGER: Exploring Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Krimigis, Stamatios M.; Acuna, Mario H.; Anderson, Brian J.; Baker, Daniel N.; Koehn, Patrick L.; Korth, Haje; Levi, Stefano; Mauk, Barry H.; Solomon, Sean C.; Zurbuchen, Thomas H.

    2005-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet s miniature magnetosphere since the brief flybys of Mariner 10. Mercury s magnetosphere is unique in many respects. The magnetosphere of Mercury is among the smallest in the solar system; its magnetic field typically stands off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed drift paths for energetic particles and, hence, no radiation belts. The characteristic time scales for wave propagation and convective transport are short and kinetic and fluid modes may be coupled. Magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to impact directly the regolith. Inductive currents in Mercury s interior may act to modify the solar wind interaction by resisting changes due to solar wind pressure variations. Indeed, observations of these induction effects may be an important source of information on the state of Mercury s interior. In addition, Mercury s magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionospheric layer. This lack of an ionosphere is probably the underlying reason for the brevity of the very intense, but short-lived, - 1-2 min, substorm-like energetic particle events observed by Mariner 10 during its first traversal of Mercury s magnetic tail. Because of Mercury s proximity to the sun, 0.3 - 0.5 AU, this magnetosphere experiences the most extreme driving forces in the solar system. All of these factors are expected to produce complicated interactions involving the exchange and re-cycling of neutrals and ions between the solar wind, magnetosphere, and regolith. The electrodynamics of Mercury s magnetosphere are expected to be equally complex, with strong forcing by the solar wind, magnetic reconnection at the magnetopause and in the tail, and the pick-up of planetary ions all

  13. Real-time prediction of magnetospheric activity using the Boyle Index

    NASA Astrophysics Data System (ADS)

    Bala, Ramkumar; Reiff, P. H.; Landivar, J. E.

    2009-04-01

    We present a new algorithm with an improvement in the accuracy and lead time in short-term space weather predictions by coupling the Boyle Index, Φ = 10-4ν2 + 11.7Bsin3(?/2) kV, to artificial neural networks. The algorithm takes inputs from ACE and a handful of ground-based magnetometers to predict the next upcoming Kp in real time. The model yields a correlation coefficient of over 86% when predicting Kp with a lead time of 1 hour and over 85% for a 2 hour ahead prediction, significantly larger than the Kp persistence of 0.80. The Boyle Index, available in near-real time from http://space.rice.edu/ISTP/wind.html, has been in use for over 5 years now to predict geomagnetic activity. The logarithm of both 3-hour and 1-hour averages of the Boyle Index correlates well with the following Kp: Kp = 8.93 log10 < Boyle Index> -12.55. Using the Boyle Index alone, the algorithm yields a correlation coefficient of 85% when predicting Kp with a lead time of 1 hour and over 84% for a 3 hour ahead prediction, nearly as good as when using Kp in the history but without any possibility of "persistence contamination." Although the Boyle Index generally overestimates the polar cap potential for severe events, it does predict that severe activity will occur. Also, 1-hour value less than 100 kV is a good indicator that the magnetosphere will be quiet. However, some storm events with Kp > 6 occur when the Boyle Index is relatively low; the new algorithm is successful in predicting those events by capturing the influence of preconditioning.

  14. Bifurcation and Hysteresis of the Magnetospheric Structure with a varying Southward IMF: Field Topology and Global Three-dimensional Full Particle Simulations

    NASA Technical Reports Server (NTRS)

    Cai, DongSheng; Tao, Weinfeng; Yan, Xiaoyang; Lembege, Bertrand; Nishikawa, Ken-Ichi

    2007-01-01

    Using a three-dimensional full electromagnetic particle model (EMPM), we have performed global simulations of the interaction between the solar wind and the terrestrial magnetosphere, and have investigated its asymptotic stability. The distance between the dayside magnetopause subsolar point and the Earth center, R(sub mp) is measured, as the intensity of southward IMF |B(sub z)| is slowly varying. Based on the field topology theory, one analyzes the variation of R(sub mp) as a reference index of the dynamics of this interaction, when IMF |B(sub z)| successively increases and decreases to its original value. Two striking results are observed. First, as the IMF |B(sub z)| increases above a critical value, the variation of R(sub mp) suddenly changes (so called 'bifurcation' process in field topology). Above this critical value, the overall magnetic field topology changes drastically and is identified as being the signature of magnetic reconnection at the subsolar point on the magnetopause. Second, this subsolar point recovers its original location R(sub mp) by following different paths as the IMF |B(sub z)| value increases (from zero to a maximum fixed value) and decreases (from this maximum to zero) passing through some critical values. These different paths are the signature of 'hysteresis' effect, and are characteristic of the so-called 'subcritical-type' bifurcation. This hysteresis signature indicates that dissipation processes take place via an energy transfer from the solar wind to the magnetosphere by some irreversible way, which leads to a drastic change in the magnetospheric field topology. This hysteresis is interpreted herein as a consequence of the magnetic reconnection taking place at the dayside magnetopause. The field topology reveals to be a very powerful tool to analyze the signatures of three-dimensional magnetic reconnection without the obligation for determining the mechanisms responsible for, and the consequences of the reconnection on the

  15. Low-dimensional chaos in magnetospheric activity from AE time series

    NASA Technical Reports Server (NTRS)

    Vassiliadis, D. V.; Sharma, A. S.; Eastman, T. E.; Papadopoulos, K.

    1990-01-01

    The magnetospheric response to the solar-wind input, as represented by the time-series measurements of the auroral electrojet (AE) index, has been examined using phase-space reconstruction techniques. The system was found to behave as a low-dimensional chaotic system with a fractal dimension of 3.6 and has Kolmogorov entropy less than 0.2/min. These indicate that the dynamics of the system can be adequately described by four independent variables, and that the corresponding intrinsic time scale is of the order of 5 min. The relevance of the results to magnetospheric modeling is discussed.

  16. High-m Poloidal Waves Observed in Low Earth Orbit and Their Implications for Energetic Particles in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Chi, P. J.; Johnson, J.; Porazik, P.

    2015-12-01

    Recent studies of the magnetic field data collected by the NASA ST-5 satellites in the low Earth orbit have revealed many wave events with frequencies of 30-200 mHz (in the Pc 2-3 band). It was soon realized that these waves were in fact Doppler-shifted waves in the magnetosphere, with wave frequencies of merely a few mHz (in the Pc 5 band) and azimuthal wavenumbers (m) of the order of 100. Oscillating in the poloidal direction, high-mwaves are known to engage in drift or drift bounce resonance with energetic ring current particles, and therefore they are expected to play a role in modulating the energetic particles in the inner magnetosphere. Using a new method that examines the differences in wave phase detected by the three ST-5 satellites in a "pearls-on-a-string" configuration, we confirm that the frequencies of the observed poloidal waves are mainly between 3 and 5 mHz in the Earth frame. In some events, the NOAA satellites were located at the equator and close to the field lines connected to the ST-5 satellites, confirming the wave frequencies estimated using only ST-5 observations. In each of the poloidal wave events observed by ST-5, the azimuthal wavenumber may change with L, but the wave frequency in the Earth frame remains the same. We have also found cases where poloidal waves were observed in both dayside and nightside of the magnetosphere when ST-5 satellite passed through the same Lshells within a single orbit, supporting the theoretical prediction of a global poloidal mode, which is also known as the transverse Alfvén resonator. Satellite observations in low Earth orbits have shown that high-m poloidal waves can last many hours even during geomagnetically quiet conditions, suggesting that a very weak ring current may be capable of supplying enough energetic particles to excite poloidal waves. We will address the implications for energetic particles in the inner magnetosphere with theoretical and modeling considerations.

  17. The Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Birmingham, T. J.

    1983-03-01

    Research on Jovian magnetospheric physics from 1979 through 1982 is surveyed, with a focus on the observations of Voyagers 1 and 2. Jovian fields and plasmas are characterized in the order of their distance from the planet, and special emphasis is given to the Io plasma torus (IPT) in the 4.9-8-Jovian-radius region and to the extended Jovian magnetotail. Topics reviewed include synchrotron radiation, magnetic-field models, Na and S emissions in the IPT, aurora, the magnetic-anomaly model, IPT plasma diffusion-convection, Io-generated Alfven wave, plasma configuration beyond the IPT, low-energy charged particles, cosmic-ray-energy particles, particle acceleration, magnetic configuration, tail current sheet and plasma disc, magnetopause and magnetosheath, interplanetary ions of Jovian origin, and the Jovian magnetosphere at Saturnian distances.

  18. Wave observations in outer planet magnetospheres

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.

    1985-01-01

    The first measurements of plasma waves and wave-particle interactions in the magnetospheres of the outer planets were provided by instruments on Voyager 1 and 2. At Jupiter, the observations yielded new information on upstream electrons and ions, bow shock dissipation processes, trapped radio waves in the magnetospheres and extended Jovian magnetotail, pitch angle diffusion mechanisms and whistlers from atmospheric lightning. Many of these same emissions were detected at Saturn. In addition, the Voyager plasma wave instruments detected dust particles associated with the tenuous outer rings of Saturn as they impacted the spacecraft. Most of the plasma wave activity at Jupiter and Saturn is in the audio range, and recordings of the wave observations have been useful for analysis.

  19. Global magnetosphere-like 3D structure formation in kinetics by hot magnetized plasma flow characterized by shape of the particle distribution function

    NASA Astrophysics Data System (ADS)

    Gubchenko, Vladimir

    The task was to provide an analytical elementary magnetosphere-like model in kinetics for verification of the 3D EM PIC codes created for space/aerospace and HED plasmas applications. Kinetic approach versus cold MHD approach takes into account different behavior in the EM fields of resonant and non resonant particles in the velocity phase space, which appears via shape characteristics of the particle velocity distribution function (PVDF) and via the spatial dispersion effect forming the collisionless dissipation in the EM fields. The external flow is a hot collisionless plasma characterized by the particle velocity distribution function (PVDF) with different shapes: Maxwellian, kappa, etc. The flow is in a “hot regime”: it can be supersonic but its velocity remains less the thermal velocity of the electrons. The “internal” part of the magnetosphere formed by trapped particles is the prescribed 3D stationary magnetization considered as a spherical “quasiparticle” with internal magnetodipole and toroidal moments represented as a broadband EM driver. We obtain after the linearization of Vlasov/Maxwell equations a self-consistent 3D large scale kinetic solution of the classic problem. Namely, we: model the “outer” part of the magnetosphere formed by external hot plasma flow of the flyby particles. Solution of the Vlasov equation expressed via a tensor of dielectric permittivity of nonmagnetized and magnetized flowing plasma. Here, we obtain the direct kinetic dissipative effect of the magnetotail formation and the opposite diamagnetic effect of the magnetosphere “dipolization”. We get MHD wave cone in flow magnetized by external guiding magnetic (GM) field. Magnetosphere in our consideration is a 3D dissipative “wave” package structure of the skinned EM fields formed by the “waves” excited at frequency bands where we obtain negative values and singularities (resonances) of squared EM refractive index of the cold plasma. The hot regime

  20. Steady Magnetospheric Convection: A Review

    NASA Astrophysics Data System (ADS)

    Fairfield, D. H.

    2004-12-01

    On occasion, solar wind energy enters Earth's magnetosphere yet the common discrete energy-dissipation events known as magnetospheric substorms fail to occur. During these times, the magnetotail assumes a configuration where earthward of about 12 Re the tail remains in a stretched tail-like state with a thin current sheet similar to the substorm growth phase. At the same time the more distant tail attains a more relaxed configuration with a thick plasma sheet, weak lobe field and enhanced northward Bz, similar to the substorm recovery phase. Simultaneously, (1) auroral zone currents remain strong and assume a two cell DP 2 convection pattern; (2) the auroral oval is wide and optically active, particularly at its poleward and equatorward edges; (3) polar cap area remains constant and energetic particle boundaries are stable, (4) earthward plasma flow persists near the center of the tail as implied by the name steady magnetospheric convection (SMC) except that it occurs on a time scale of minutes and the flow remains bursty. These small scale flows in the tail correspond to auroral streamers that form near the poleward boundary of the oval and propagate equatorward in a few minutes time. Although SMC events have some substorm-like characteristics, such as Pi2's, particle injections and region 1-type field aligned currents with their associated westward ionospheric currents, such phenomena occur on much shorter time and spatial scales and with much smaller amplitudes than actual substorms. Modeling the global magnetic field for several specific SMC events suggest that a minimum in the equatorial tail field Bz magnitude exists near 12 Re which may correspond to the one known equilibrium field configuration that can avoid the pressure catastrophe that may correspond to substorms. This unique field configuration may permit the return of magnetic flux to the dayside that allows the persistence of the steady state field configuration.

  1. Magnetospheres of the outer planets

    SciTech Connect

    Cheng, A.F.

    1986-12-01

    The magnetospheres of the outer planets have been shown by Voyager explorations to strongly interact with the surfaces and atmospheres of their planetary satellites and rings. In the cases of Jupiter, Saturn and Uranus, the processes of charged particle sputtering, neutral gas cloud formation, and rapid plasma injection from the ionization of the neutral clouds, have important implications both for the magnetospheres as a whole and for the surfaces and atmospheres of their satellites. The general methodology employed in these researches has involved comparisons of the planetary magnetospheres in order to identify common physical processes. 16 references.

  2. Earth's magnetosphere - Global problems in magnetospheric plasma physics

    NASA Technical Reports Server (NTRS)

    Roederer, J. G.

    1979-01-01

    Magnetospheric physics is presently in a transition from the exploratory stage to one in which satellite missions and ground-based observations are planned with the specific object of achieving a global understanding and self-consistent quantitative description of the cause-and-effect relationship among the principal dynamic processes involved. Measurements turn to lower and lower energies and to higher ion mass species, in order to encompass the entire particle population, and to a broader range of the frequency spectrum of magnetic and electric field variations. In the present paper, the current status of our knowledge on magnetospheric plasma physics is reviewed, with particular reference of such fundamental advances as the discovery of layers of streaming plasma in the magnetosphere beneath its boundary surface, the identification of the terrestrial magnetosphere as a celestial source of kilometric radiation and relativistic particles, the identification of parallel electric field regions within the magnetosphere and their role in auroral particle acceleration, and the discovery of large fluxes of energetic heavy ions trapped in the magnetosphere.

  3. Dynamics of Saturn's magnetosphere from MIMI during Cassini's orbital insertion.

    PubMed

    Krimigis, S M; Mitchell, D G; Hamilton, D C; Krupp, N; Livi, S; Roelof, E C; Dandouras, J; Armstrong, T P; Mauk, B H; Paranicas, C; Brandt, P C; Bolton, S; Cheng, A F; Choo, T; Gloeckler, G; Hayes, J; Hsieh, K C; Ip, W-H; Jaskulek, S; Keath, E P; Kirsch, E; Kusterer, M; Lagg, A; Lanzerotti, L J; Lavallee, D; Manweiler, J; McEntire, R W; Rasmuss, W; Saur, J; Turner, F S; Williams, D J; Woch, J

    2005-02-25

    The Magnetospheric Imaging Instrument (MIMI) onboard the Cassini spacecraft observed the saturnian magnetosphere from January 2004 until Saturn orbit insertion (SOI) on 1 July 2004. The MIMI sensors observed frequent energetic particle activity in interplanetary space for several months before SOI. When the imaging sensor was switched to its energetic neutral atom (ENA) operating mode on 20 February 2004, at approximately 10(3) times Saturn's radius RS (0.43 astronomical units), a weak but persistent signal was observed from the magnetosphere. About 10 days before SOI, the magnetosphere exhibited a day-night asymmetry that varied with an approximately 11-hour periodicity. Once Cassini entered the magnetosphere, in situ measurements showed high concentrations of H+, H2+, O+, OH+, and H2O+ and low concentrations of N+. The radial dependence of ion intensity profiles implies neutral gas densities sufficient to produce high loss rates of trapped ions from the middle and inner magnetosphere. ENA imaging has revealed a radiation belt that resides inward of the D ring and is probably the result of double charge exchange between the main radiation belt and the upper layers of Saturn's exosphere. PMID:15731445

  4. Solar Wind Entry into the magnetosphere lobes and its Related Auroral activities

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Gou, X.; Mailyan, B. G.; Maggiolo, R.; Zhang, Y.; Fu, S.; Zong, Q.; Parks, G. K.; Pu, Z.; Dunlop, M. W.

    2014-12-01

    Using Cluster multi-spacecrafts observation between August to October each year from 2002 to 2004, Shi, et al. [2013] have reported an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetospheric lobes where the solar wind plasmas may penetrate into magnetosphere through high-latitude magnetic reconnection when the interplanetary magnetic field (IMF) is northward. From statistical analysis, they found that the IMF Bx component may influence the solar wind entry into the magnetosphere by changing the occurring conditions of high-latitude magnetic reconnection. Based on their studies, in this paper we use another period of Cluster data which is between January to April each year from 2001 to 2006 to do a further study. As a result, the influence of the IMF Bx component is consistent with the results from [Shi, et al. 2013]. We find that the IMF By component affects the events along with the IMF Bx component, which is consistent with the Parker Spiral of the IMF. We have also studied some transpolar arc observations in correlation with the solar wind entry events. The properties of entry plasma, electron and ion properties associated with aurorae are examined using multiple spacecraft data (Cluster, TIMED, DMSP, IMAGE and POLAR etc) , as can be seen from another work presented this meeting by Mailyan et al.

  5. The Role of Bubbles in the Transport of Particles From the Plasma Sheet to the Inner Magnetosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Wolf, R.; Yang, J.; Toffoletto, F.; Sazykin, S. Y.

    2013-12-01

    Essentially the whole closed-field-line region of the magnetosphere is stratified, with layers of highest PV5/3 on field lines that stretch far into the tail and lowest PV5/3 deep in the inner magnetosphere. (Here V is the volume of a flux tube containing a unit of magnetic flux.) The magnetosphere is like an atmosphere with heavy gases on the bottom and lighter ones on the top. The entropy parameter PV5/3 is strictly conserved in ideal MHD. Transport nevertheless occurs between layers, because a non-ideal process like a patch of reconnection can create a bubble of low PV5/3 that propagates rapidly earthward, forming a bursty bulk flow. During that rapid earthward motion, the earthward boundary of the bubble forms a dipolarization front, where the magnetic field switches from the background stretched configuration to a more dipolar shape inside the bubble. A thin layer of high-PV5/3 flux tubes gets pushed earthward ahead of the bubble (known feature of dipolarization fronts). The bubble slows after it reaches the region where the PV5/3 of the surrounding medium matches its own, and it is sometimes observed to oscillate about an equilibrium position. While bubbles have obvious effects in the plasma sheet, their effects on the inner magnetosphere are much less obvious. Gradient/curvature drift, which is strong in the inner magnetosphere, causes higher-energy ions in the bubble to drift west compared to the bubble center and lower-energy ions and electrons to drift east. Thus the bubble blends into its surroundings. This picture of transport by bubbles has become well established for the plasma sheet, but conventional ring current models do not consider it, envisaging injection as a result of an increase in global convection. The key question is: do bubbles have any observable signatures in the storm-time ring current? Results will be presented from RCM-E runs designed to answer this question.

  6. Movement of particles using sequentially activated dielectrophoretic particle trapping

    DOEpatents

    Miles, Robin R.

    2004-02-03

    Manipulation of DNA and cells/spores using dielectrophoretic (DEP) forces to perform sample preparation protocols for polymerized chain reaction (PCR) based assays for various applications. This is accomplished by movement of particles using sequentially activated dielectrophoretic particle trapping. DEP forces induce a dipole in particles, and these particles can be trapped in non-uniform fields. The particles can be trapped in the high field strength region of one set of electrodes. By switching off this field and switching on an adjacent electrodes, particles can be moved down a channel with little or no flow.

  7. Origins of magnetospheric plasma

    SciTech Connect

    Moore, T.E. )

    1991-01-01

    A review is given of recent (1987-1990) progress in understanding of the origins of plasmas in the earth's magnetosphere. In counterpoint to the early supposition that geomagnetic phenomena are produced by energetic plasmas of solar origin, 1987 saw the publication of a provocative argument that accelerated ionospheric plasma could supply all magnetospheric auroral and ring current particles. Significant new developments of existing data sets, as well as the establishment of entirely new data sets, have improved the ability to identify plasma source regions and to track plasma through the magnetospheric system of boundary layers and reservoirs. These developments suggest that the boundary between ionospheric and solar plasmas, once taken to lie at the plasmapause, actually lies much nearer to the magnetopause. Defining this boundary as the surface where solar wind and ionosphere contribute equally to the plasma, it is referred to herein as the 'geopause'. It is now well established that the infusion of ionospheric O(+) plays a major role in the storm-time distention of the magnetotail and inflation of the inner magnetosphere. After more than two decades of observation and debate, the question remains whether magnetosheric are protons of solar or terrestrial origin. 161 refs.

  8. An analytical estimate of the coefficient for radial charged particle diffusion in Jupiter's magnetosphere using plasma radial distribution

    NASA Astrophysics Data System (ADS)

    Gubar, Yu. I.

    2015-11-01

    A radial profile of the plasma mass distribution in Jupiter's magnetosphere in the region beyond Io's orbit up to ˜15 Jupiter radii R J constructed according to the results of measurements on the Voyager 1 and Galileo spacecraft is used to determine the radial dependence and radial diffusion coefficient D LL . The initial profile is approximated by a function decreasing as L -5 ± 1. For this radial mass distribution, radial ion diffusion outside of Io's orbit caused by centrifugal forces is possible. An estimate of (1.2-6.7)10-11 L 6 ± 1 for D LL was obtained.

  9. Measurements from the Van Allen Probes EFW instrument on the role of electric fields in controlling the structure of the inner magnetosphere and the dynamic of particle energization

    NASA Astrophysics Data System (ADS)

    Wygant, J. R.; Breneman, A. W.; Dai, L.; Thaller, S. A.; Cattell, C. A.; Bonnell, J. W.; Mozer, F.; Agapitov, O. V.; Ergun, R.; Baker, D. N.; Li, X.; Califf, S.; Malaspina, D.; Hudson, M. K.; Millan, R. M.; Halford, A.; Foster, J. C.; Erickson, P. J.; Strangeway, R. J.; Donovan, E.; Kletzing, C.; Kurth, W. S.; Bounds, S. R.; Fennell, J. F.; Reeves, G. D.; Smith, C. W.; Ukhorskiy, A. Y.; Gkioulidou, M.

    2014-12-01

    The Van Allen Probes electric field experiment (EFW) provides measurements in the inner magnetosphere of quasi-static electric fields and high time resolution burst recordings of wave electric and magnetic fields (from the EMFISIS sensors) at rates as high as 16.4 ksamples/s. The EFW instrument also provides estimates of plasma density. We present electric field measurements from the two probes of these electric fields along with magnetic fields and particles to illustrate the role of the electric fields in the erosion of the plasmasphere, the energization of ring current particles, shock acceleration of relativistic particles, and near earth plasma sheet injection of energetic particles. These analysis include comparisons to dc magnetic fields provided by the EMFISIS fluxgate magnetometer and energetic particle measurements (from 10 eV to 20 MeV) provided by HOPE, MagEIS, and REPT instruments in the ECT suite. We will also present a preliminary comparison over the complete duration of the mission between the structure and intensity of the large-scale convection electric field and its interplanetary drivers, including CMEs and SIRs.

  10. The magnetospheric interaction of Dione in the view of energetic particles: Cassini MIMI/LEMMS results during the encounters D1-D3

    NASA Astrophysics Data System (ADS)

    Krupp, N.; Roussos, E.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Khurana, K. K.

    2012-04-01

    Low Energy Magnetospheric Measurement System (LEMMS) data are presented from the three Dione flybys of the Cassini spacecraft between 2005 and 2011. We observed absorption signatures in the fluxes of electrons with energies between 20 keV and several MeV. The signatures are dependent on the flyby geometry. The two downstream flybys D2 and D3 show clearly an asymmetry which becomes stronger for higher energies. The most prominent signature of this asymmetry is a much sharper flux drop-out at the Saturn-facing wake boundary consistent with particle tracing simulation results. The absorption in higher-energy channels (several hundreds of keV) is more sporadic. Differences between the results of D2 and D3 are caused by the flyby distance and from the fact that during D2 the magnetosphere was very much disturbed in an ongoing injection event at that time. The flyby D1 was slightly south and upstream of the moon partially crossing the magnetic flux tube. The result during that flyby is an absorption in the higher-energy channels with the size of the moon while the signature in lower-energy channels is only half of it. The reason is that only part of the flux tube was crossed by Cassini. Energetic ion observation also show absorption features with an energy-dependent position relative to the geometrical moon's wake consistent with gyroradius effects. We interpret the results as evidence of particle absorption at the moon but also an indication that energy dependent particle trajectories around the moon can cause features in the moon's wake.

  11. Oscillatory flow braking: inner magnetosphere observations

    NASA Astrophysics Data System (ADS)

    Panov, E. V.; Nakamura, R.; Baumjohann, W.; Angelopoulos, V.

    2013-12-01

    We search for damped oscillatory flow braking events observed by THEMIS/ARTEMIS in the near-Earth plasma sheet when their counterpart in the inner magnetosphere was observed. By comparing the particle and magnetic field data in the two locations we analyze the feedback of the inner magnetosphere to plasma sheet oscillatory flow braking. We discuss the possible role of the oscillatory flow events for plasma injection into the inner magnetosphere.

  12. The earth's magnetosphere

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.

    1976-01-01

    The following aspects of the earth's magnetosphere were discussed: general structure, magnetic field merging and magnetospheric convection, time-varying convection and magnetospheric substorms, magnetic storms, and comparative magnetospheres. Solar flares and the magnetospheres of Mercury, Venus, Mars, Jupiter, Saturn, and Uranus were also described.

  13. The irregular Pi3 geomagnetic pulsations and its connection with the energetic particles in the magnetosphere and ionosphere

    NASA Astrophysics Data System (ADS)

    Belakhovsky, Vladimir; Pilipenko, Vjacheslav

    2015-04-01

    In this study we investigate the nighttime irregular Pi3 type geomagnetic pulsations generated as during strong single substorms as during sawtooth events using modern satellite (GOES, THEMIS) and ground-based observations (CARISMA, THEMIS, NORSTAR). These pulsations developed during all substorm period but not only during substorm growth phase as ordinary Pi2 pulsations. The maximum intensity of these pulsations lies in auroral zone (~66° CGL). It is seen a good correspondence between Pi3 geomagnetic pulsations on the ground-based magnetometers of the CARISMA network and on the GOES geostationary spacecraft, THEMIS spacecrafts which located at ~10 Re in the magnetosphere tail. It is seen strong increase of the fluxes of the electrons on GOES, THEMIS spacecrafts, increase of CNA on the NORSTAR riometers, increase of the aurora intensity on the THEMIS all-sky imagers during the beginning of the substrom. The considered irregular Pi3 pulsations strongly modulate the fluxes of the electrons in the magnetosphere at GOES, THEMIS spacecrafts and CNA, aurora intensity. But there is no close phase correspondence between the Pi3 pulsations in the geomagnetic field and fluxes of the trapped and precipitated electrons. At the same time there is no simultaneous geomagnetic pulsations in the same frequency rage was observed on the dayside (IMAGE network). We suppose that these Pi3 pulsations have another physical nature than dayside Pc5 pulsations. The Pi3 geomagnetic pulsations may be generated due to proper geomagnetic tail oscillations during substorm development.

  14. Studies of the composition of solar particles and of energetic oxygen and sulfur nuclei trapped in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1986-01-01

    The Cosmic Ray System (CRS) experiment on board each of the Voyager 1 and 2 spacecraft consists of four Low Energy Telescopes (LETs), two High Energy Telescopes (HETs), the Electron Telescope (TET), and associated electronics. With these instruments it is possible to measure the energy spectrum of electrons over the 3-110MeV energy range and the energy spectra and nuclear charge of atomic nuclei from hydrogen through zinc over the 3-500 MeV/nuc energy range. The exclusive use of solid-state detectors in the CRS telescopes achieves the objectives of reliability over a long mission life, high resolution determinations of energy and charge, and high-count-rate capability during large solar flares and passage through the magnetospheres of the outer planets. Summarized here are some of the many accomplishments that have resulted from the CRS measurements during the period covered by this report, May 15, 1981 to May 15, 1984, including studies of the energetic oxygen and sulfur nuclei trapped in the Jovian magnetosphere.

  15. The solar wind and magnetospheric dynamics

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1974-01-01

    The dynamic processes involved in the interaction between the solar wind and the earth's magnetosphere are reviewed. The evolution of models of the magnetosphere is first surveyed. The existence of the auroral substorm and the cyclical polar magnetic substorm is evidence that the magnetosphere is a dynamic system. The dynamic changes occurring in the magnetosphere, including erosion of the magnetopause, changes in the size of the polar cap, variations in the flaring angle of the tail, neutral point formation, plasma sheet motions, and the inward collapse of the midnight magnetosphere, are discussed. The cyclical variations of geomagnetic activity are explained in terms of the control of the solar wind-magnetosphere interaction by the north-south component of the interplanetary magnetic field. Present phenomenological models allow prediction of geomagnetic activity from interplanetary measurements, but modeling of detailed magnetospheric processes is still in its infancy.

  16. The Magnetospheric Multiscale Mission

    NASA Astrophysics Data System (ADS)

    Burch, James

    Magnetospheric Multiscale (MMS), a NASA four-spacecraft mission scheduled for launch in November 2014, will investigate magnetic reconnection in the boundary regions of the Earth’s magnetosphere, particularly along its dayside boundary with the solar wind and the neutral sheet in the magnetic tail. Among the important questions about reconnection that will be addressed are the following: Under what conditions can magnetic-field energy be converted to plasma energy by the annihilation of magnetic field through reconnection? How does reconnection vary with time, and what factors influence its temporal behavior? What microscale processes are responsible for reconnection? What determines the rate of reconnection?
In order to accomplish its goals the MMS spacecraft must probe both those regions in which the magnetic fields are very nearly antiparallel and regions where a significant guide field exists. From previous missions we know the approximate speeds with which reconnection layers move through space to be from tens to hundreds of km/s. For electron skin depths of 5 to 10 km, the full 3D electron population (10 eV to above 20 keV) has to be sampled at rates greater than 10/s. The MMS Fast-Plasma Instrument (FPI) will sample electrons at greater than 30/s. Because the ion skin depth is larger, FPI will make full ion measurements at rates of greater than 6/s. 3D E-field measurements will be made by MMS once every ms. MMS will use an Active Spacecraft Potential Control device (ASPOC), which emits indium ions to neutralize the photoelectron current and keep the spacecraft from charging to more than +4 V. Because ion dynamics in Hall reconnection depend sensitively on ion mass, MMS includes a new-generation Hot Plasma Composition Analyzer (HPCA) that corrects problems with high proton fluxes that have prevented accurate ion-composition measurements near the dayside magnetospheric boundary. Finally, Energetic Particle Detector (EPD) measurements of electrons and

  17. Solar wind energy transfer through the magnetopause of an open magnetosphere

    NASA Technical Reports Server (NTRS)

    Lee, L. C.; Roederer, J. G.

    1982-01-01

    An expression is derived for the total power, transferred from the solar wind to an open magnetosphere, which consists of the electromagnetic energy rate and the particle kinetic energy rate. The total rate of energy transferred from the solar wind to an open magnetosphere mainly consists of kinetic energy, and the kinetic energy flux is carried by particles, penetrating from the solar wind into the magnetosphere, which may contribute to the observed flow in the plasma mantle and which will eventually be convected slowly toward the plasma sheet by the electric field as they flow down the tail. While the electromagnetic energy rate controls the near-earth magnetospheric activity, the kinetic energy rate should dominate the dynamics of the distant magnetotail.

  18. The magnetosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Ness, N. F.

    1976-01-01

    Data on Mercury's magnetosphere and on the plasma, planetomagnetic, and energetic particle environment of the planet obtained in three encounters (Mariner 10 flybys) are compared, and tasks for future research are outlined. The Mercury bow shock and magnetopause are much closer to the planet than the earth counterparts are to the earth. The magnetotail with embedded plasma sheet-field reversal region, global deflection of the solar wind by an intrinsic dipolar magnetic field, variations in solar wind momentum flux, and absence of such features as ionosphere, plasmasphere, and radiation belts, are described. Energetic electrons are accelerated in the magnetotail, however, and the interplanetary magnetic field variations distort Mercury's magnetosphere to produce a southward field associated with substorm-like disturbances.

  19. Multi-point observations of energetic particle injection deep into the inner magnetosphere: Implications for the ring current and radiation belts

    NASA Astrophysics Data System (ADS)

    Reeves, G. D.; Larsen, B.; Friedel, R. H. W.; Henderson, M. G.; Skoug, R. M.; Funsten, H. O.; Claudepierre, S. G.; Fennell, J.; Tu, W.; Cunningham, G.; Spence, H. E.

    2014-12-01

    For thirty years, the "injection boundary" model of substorm injections has provided a framework for studies of the impulsive transport of energetic electrons and ions into the inner magnetosphere. New, multi-satellite observations of substorm injections show signatures that require revision and rethinking of the classical picture. Recent observations by the LANL-GEO and GOES energetic particle instruments provide unprecedented coverage at geosynchronous orbit while the Van Allen Probes satellites provide simultaneous multi-point measurements inside geosynchronous orbit. With these satellites we can observe injections at three different radial distances and up to ten different local times - simultaneously. These observations reveal a complex and varied set of dynamics that have important implications for the development of the radiation belts and ring current. In this study we look specifically at the radial penetration of energetic particle injections in storms and substorms. Radial alignments of satellites confirm and extend the CRRES/LANL-GEO observations of relatively slow inward propagation of the injection region inside geosynchronous orbit [1]. At the same time, synoptic Van Allen Probes observations show frequent storm-time "injection" of energetic (~50-500 keV) electrons to very low L-shells (L < 3) that have not previously been reported. The radial distribution of electrons and ions injected during storms and substorms have profound implications for the generation of waves, for the availability of a radiation belt "seed population", and for the radial distribution of ring current ions. In this paper we will use multi-point satellite observations to understand the processes that inject energetic particles into the inner magnetosphere, the Earthward propagation of these injections, the conditions that control variation in Earthward extent of energetic particle injections, and how particles can be injected deep inside the plasmasphere and even through the

  20. Characteristics of solar wind control on Jovian UV auroral activity deciphered by long-term Hisaki EXCEED observations: Evidence of preconditioning of the magnetosphere?

    NASA Astrophysics Data System (ADS)

    Kita, Hajime; Kimura, Tomoki; Tao, Chihiro; Tsuchiya, Fuminori; Misawa, Hiroaki; Sakanoi, Takeshi; Kasaba, Yasumasa; Murakami, Go; Yoshioka, Kazuo; Yamazaki, Atsushi; Yoshikawa, Ichiro; Fujimoto, Masaki

    2016-07-01

    While the Jovian magnetosphere is known to have the internal source for its activity, it is reported to be under the influence of the solar wind as well. Here we report the statistical relationship between the total power of the Jovian ultraviolet aurora and the solar wind properties found from long-term monitoring by the spectrometer EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) on board the Hisaki satellite. Superposed epoch analysis indicates that auroral total power increases when an enhanced solar wind dynamic pressure hits the magnetosphere. Furthermore, the auroral total power shows a positive correlation with the duration of a quiescent interval of the solar wind that is present before a rise in the dynamic pressure, more than with the amplitude of dynamic pressure increase. These statistical characteristics define the next step to unveil the physical mechanism of the solar wind control on the Jovian magnetospheric dynamics.

  1. Electromagnetic ion cyclotron waves stimulated by modest magnetospheric compressions

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Hamilton, D. C.

    1993-01-01

    AMPTE/CCE magnetic field and particle data are used to test the suggestion that increased hot proton temperature anisotropy resulting from convection during magnetospheric compression is responsible for the enhancement in Pc 1 emission via generation of electromagnetic ion cyclotron (EMIC) waves in the dayside outer equatorial magnetosphere. The relative increase in magnetic field is used to gauge the strength of the compression, and an image dipole model is used to estimate the motion of the plasma during compression. Proton data are used to analyze the evolution of the proton distribution and the corresponding changes in EMIC wave activity expected during the compression. It is suggested that enhancements in dynamic pressure pump the energetic proton distributions in the outer magnetosphere, driving EMIC waves. Waves are expected to be generated most readily close to the magnetopause, and transient pressure pulses may be associated with bursts of EMIC waves, which would be observed on the ground in association with ionospheric transient signatures.

  2. Deep Solar Activity Minimum 2007-2009: Solar Wind Properties and Major Effects on the Terrestrial Magnetosphere

    NASA Technical Reports Server (NTRS)

    Farrugia, C. J.; Harris, B.; Leitner, M.; Moestl, C.; Galvin, A. B.; Simunac, K. D. C.; Torbert, R. B.; Temmer, M. B.; Veronig, A. M.; Erkaev, N. V.; Szabo, A.; Ogilvie, K. W.; Luhman, J. G.; Osherovich, V. A.

    2012-01-01

    We discuss the temporal variations and frequency distributions of solar wind and interplanetary magnetic field parameters during the solar minimum of 2007 - 2009 from measurements returned by the IMPACT and PLASTIC instruments on STEREO-A.We find that the density and total field strength were significantly weaker than in the previous minimum. The Alfven Mach number was higher than typical. This reflects the weakness of magnetohydrodynamic (MHD) forces, and has a direct effect on the solar wind-magnetosphere interactions.We then discuss two major aspects that this weak solar activity had on the magnetosphere, using data from Wind and ground-based observations: i) the dayside contribution to the cross-polar cap potential (CPCP), and ii) the shapes of the magnetopause and bow shock. For i) we find a low interplanetary electric field of 1.3+/-0.9 mV/m and a CPCP of 37.3+/-20.2 kV. The auroral activity is closely correlated to the prevalent stream-stream interactions. We suggest that the Alfven wave trains in the fast streams and Kelvin-Helmholtz instability were the predominant agents mediating the transfer of solar wind momentum and energy to the magnetosphere during this three-year period. For ii) we determine 328 magnetopause and 271 bow shock crossings made by Geotail, Cluster 1, and the THEMIS B and C spacecraft during a three-month interval when the daily averages of the magnetic and kinetic energy densities attained their lowest value during the three years under survey.We use the same numerical approach as in Fairfield's empirical model and compare our findings with three magnetopause models. The stand-off distance of the subsolar magnetopause and bow shock were 11.8 R(sub E) and 14.35 R(sub E), respectively. When comparing with Fairfield's classic result, we find that the subsolar magnetosheath is thinner by approx. 1 R(sub E). This is mainly due to the low dynamic pressure which results in a sunward shift of the magnetopause. The magnetopause is more flared

  3. Deep Solar Activity Minimum 2007-2009: Solar Wind Properties and Major Effects on the Terrestrial Magnetosphere

    NASA Astrophysics Data System (ADS)

    Farrugia, C. J.; Harris, B.; Leitner, M.; Möstl, C.; Galvin, A. B.; Simunac, K. D. C.; Torbert, R. B.; Temmer, M. B.; Veronig, A. M.; Erkaev, N. V.; Szabo, A.; Ogilvie, K. W.; Luhmann, J. G.; Osherovich, V. A.

    2012-04-01

    We discuss the temporal variations and frequency distributions of solar wind and interplanetary magnetic field parameters during the solar minimum of 2007- 2009 from measurements returned by the IMPACT and PLASTIC instruments on STEREO-A. We find that the density and total field strength were considerably weaker than in the previous minimum. The Alfvén Mach number was higher than typical. This reflects the weakness of magnetohydrodynamic (MHD) forces, and has a direct effect on the solar wind-magnetosphere interactions. We then discuss two major aspects that this weak solar activity had on the magnetosphere using data from Wind and ground-based observations: (a) the level of solar wind driving and the associated dayside contribution to the crosspolar cap potential (CPCP), and (b) the shapes of the magnetopause and bow shock. For (a) we find very weak interplanetary electric field (V xBz = -0.05 ± 0.83 mV/m) and a CPCP of 36.6 ± 18.2 kV. The auroral activity is closely correlated to the prevalent stream-stream interactions.We argue that the Alfvén waves in the fast streams and Kelvin-Helmholtz instability were the predominant agents mediating the transfer of solar wind momentum and energy to the magnetosphere during this 3-year period. For (b) we determine 328 magnetopause and 271 bow shock crossings made by the Cluster 1, Themis B and C spacecraft during a 3-month interval when the daily averages of the magnetic and kinetic energy densities attained their lowest value during the 3 years under survey. We use the same numerical approach as in Fairfield's (1971) empirical model and compare our findings with his classic result. The stand-off distance of the subsolar magnetopause and bow shock were 11.8 RE and 14.35 RE, respectively, making the subsolar magnetosheath thinner by ≈ 1RE. This is mainly due to the low dynamic pressure which result in a sunward shift of the magnetopause The magnetopause is more flared than Fairfield's result. By contrast the bow shock

  4. Deep Solar Activity Minimum 2007-2009: Solar Wind Properties and Major Effects on the Terrestrial Magnetosphere

    NASA Astrophysics Data System (ADS)

    Farrugia, C. J.; Harris, B. S.; Leitner, M.; Moestl, C.; Galvin, A. B.; Simunac, K.; Torbert, R. B.; Temmer, M.; Veronig, A.; Erkaev, N.; Szabo, A.; Ogilvie, K. W.; Luhmann, J. G.; Osherovich, V.

    2012-12-01

    We discuss the temporal variations and frequency distributions of solar wind and IMF parameters during the solar minimum of 2007-2009 from measurements returned by the IMPACT and PLASTIC instruments on STEREO-A. We find that the density and total field strength were significantly weaker than in the previous minimum. The Alfvén Mach number was higher than typical.This reflects the weakness of magnetohydrodynamic (MHD) forces, and has a direct effect on the solar wind-magnetosphere interactions. We then discuss two major aspects that this weak solar activity had on the magnetosphere, using data from textit{Wind} and ground-based observations: (a) the dayside contribution to the cross-polar cap potential (CPCP), and (b) the shapes of the magnetopause and bow shock. For (a) we find a low interplanetary electric field of 1.3 ± 0.9 mV m-1 and a CPCP of 37.3 ± 20.2 kV. The auroral activity is closely correlated to the prevalent stream-stream interactions. We suggest that the Alfvén wave trains in the fast streams and Kelvin-Helmholtz instability were the predominant agents mediating the transfer of solar wind momentum and energy to the magnetosphere during this three-year period. For (b) we determine 328 magnetopause and 271 bow shock crossings made by textit{Geotail, Cluster 1}, and the THEMIS B and C spacecraft during a three-month interval when the daily averages of the magnetic and kinetic energy densities attained their lowest value during the three years under survey. We use the same numerical approach as in Fairfield's (textit{J. Geophys. Res.} 76, 7600, 1971) empirical model and compare our findings with three magnetopause models. The stand-off distance of the subsolar magnetopause and bow shock were 11.8 RE and 14.35 RE, respectively. When comparing with Fairfield's (1971) classic result, we find that the subsolar magnetosheath is thinner by ˜1 RE. This is mainly due to the low dynamic pressure which results in a sunward shift of the magnetopause The

  5. Physics of magnetospheric boundary layers

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1995-01-01

    This final report was concerned with the ideas that: (1) magnetospheric boundary layers link disparate regions of the magnetosphere-solar wind system together; and (2) global behavior of the magnetosphere can be understood only by understanding its internal linking mechanisms and those with the solar wind. The research project involved simultaneous research on the global-, meso-, and micro-scale physics of the magnetosphere and its boundary layers, which included the bow shock, the magnetosheath, the plasma sheet boundary layer, and the ionosphere. Analytic, numerical, and simulation projects were performed on these subjects, as well as comparisons of theoretical results with observational data. Other related activity included in the research included: (1) prediction of geomagnetic activity; (2) global MHD (magnetohydrodynamic) simulations; (3) Alfven resonance heating; and (4) Critical Ionization Velocity (CIV) effect. In the appendixes are list of personnel involved, list of papers published; and reprints or photocopies of papers produced for this report.

  6. The magnetospheric lobe at geosynchronous orbit

    SciTech Connect

    Thomsen, M.F.; Bame, S.J.; McComas, D.J.

    1994-09-01

    On rare occasions, satellites at geosynchronous altitude enter the magnetospheric lobe, characterized by extremely low ion fluxes between 1 eV and 40 keV and electron fluxes above a few hundred eV. One year of plasma observations from two simultaneously operating spacecraft at synchronous orbit is surveyed for lobe encounters. A total of 34 full encounters and 56 apparent near encounters are identified, corresponding to {approximately}0.06% of the total observation time. Unlike energetic particle (E>40 keV) dropouts studied earlier, there is a strong tendency for the lobe encounters to occur postmidnight, as late as 07 local time. The two spacecraft encounter the lobe with different rates and in different seasons. These occurrence properties are not simply explicable in terms of the orbital geometry in either the solar magnetic or the geocentric solar magnetospheric coordinate system. A composite coordinate system which previously organized more energetic particle dropouts is somewhat more successful in organizing the lobe encounters, suggesting that solar wind distortion of the magnetic equatorial plane away from the dipole location and toward the antisolar direction may be largely responsible for these dropouts. The authors results further suggest that this distortion persists even sunward of the dawn-dusk terminator. However, a simple dawn-dusk symmetric distortion does not fully account for all the seasonal and local time asymmetries in the occurrence of the lobe encounters; thus there is probably an additional dawn-dusk asymmetry in the distorted field. The lobe encounters are strongly associated with magnetospheric activity and tend to occur in association with rare magnetosheath encounters at synchronous orbit. It thus appears that the presence of the lobe at geosynchronous orbit is the result of major, probably asymmetric modifications of the magnetospheric field geometry in times of strong disturbance. 19 refs., 7 figs., 1 tab.

  7. Dressed active particles in spherical crystals.

    PubMed

    Yao, Zhenwei

    2016-08-17

    We investigate the dynamics of an active particle in two-dimensional spherical crystals, which provide an ideal environment to illustrate the interplay between active particles and crystallographic defects. A moving active particle is observed to be surrounded by localized topological defects, becoming a dressed active particle. Such a physical picture characterizes both the lattice distortion around the moving particle and the healing of the distorted lattice in its trajectory. We find that the dynamical behaviors of an active particle in both random and ballistic motions uniformly conform to this featured scenario, whether the particle is initially a defect or not. We further observe that the defect pattern around a dressed ballistic active particle randomly oscillates between two well-defined wing-like defect motifs regardless of its speed. The established physical picture of dressed active particles in this work partially deciphers the complexity of the intriguing nonequilibrium behaviors in active crystals, and opens the promising possibility of introducing the activity to engineer defects, which has strong connections with the design of materials. PMID:27491597

  8. The magnetospheric trough

    SciTech Connect

    Thomsen, M.F.; McComas, D.J.; Elphic, R.C.; Borovsky, J.E.

    1997-03-04

    The authors review the history of the concepts of the magnetospheric cold-ion trough and hot-electron trough and conclude that the two regions are actually essentially the same. The magnetospheric trough may be viewed as a temporal state in the evolution of convecting flux tubes. These flux tubes are in contact with the earth`s upper atmosphere which acts both as a sink for precipitating hot plasma sheet electrons and as a source for the cold ionospheric plasma leading to progressive depletion of the plasma sheet and refilling with cold plasma. Geosynchronous plasma observations show that the rate of loss of plasma-sheet electron energy density is commensurate with the precipitating electron flux at the low-latitude edge of the diffuse aurora. The rate at which geosynchronous flux tubes fill with cold ionospheric plasma is found to be consistent with previous estimates of early-time refilling. Geosynchronous observations further indicate that both Coulomb collisions and wave-particle effects probably play a role in trapping ionospheric material in the magnetosphere.

  9. How Ionospheric Ions Populate the Magnetosphere during a Magnetic Storm

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, T. E.; Kistler, L. M.; Slinker, S. P.; Fedder, J. A.; Delcourt, D. C.

    2008-01-01

    Ionospheric oxygen ions have been observed throughout the magnetosphere, from the plasma sheet to the ring current region. I t has been found that the O+ /H+ density ratio in the magnetosphere increases with geomagnetic activity and varies with storm phases. During the magnetic storm in late September to earIy October 2002, Cluster was orbiting in the plasma sheet and ring current regions. At prestorm time, Cluster observed high H+ density and low O+ density in the plasma sheet and lobes. During the storm main phase, 0+ density has increased by 10 times over the pre-storm level. Strong field-aligned beams of O+ were observed in the lobes. O+ fluxes were significantly reduced in the central plasma sheet during the storm recovery. However, 0+ was still evident on the boundaries of the plasma sheet and in the lobes. In order to interpret the Cluster observations and to understand how O+ ions populate the magnetosphere during a magnetic storm, we model the storm in early October 2002 using our global ion kinetic simulation (GIK). We use the LFN global simulation model to produce electric and magnetic fields in the outer magnetosphere, the Strangeway outflow scaling with Delcourt ion trajectories to include ionospheric outflows, and the Fok inner magnetospheric model for the plasmaspheric and ring current response to all particle populations. We find that the observed composition features are qualitatively reproduced by the simulations, with some quantitative differences that point to future improvements in the models.

  10. Ratchet transport powered by chiral active particles

    PubMed Central

    Ai, Bao-quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a ‘sea’ of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles. PMID:26795952

  11. Ratchet transport powered by chiral active particles

    NASA Astrophysics Data System (ADS)

    Ai, Bao-Quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a ‘sea’ of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles.

  12. Ratchet transport powered by chiral active particles.

    PubMed

    Ai, Bao-quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a 'sea' of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles. PMID:26795952

  13. Calculations of the integral invariant coordinates I and L* in the magnetosphere and mapping of the regions where I is conserved, using a particle tracer (ptr3D v2.0), LANL*, SPENVIS, and IRBEM

    NASA Astrophysics Data System (ADS)

    Konstantinidis, K.; Sarris, T.

    2015-09-01

    The integral invariant coordinate I and Roederer's L or L* are proxies for the second and third adiabatic invariants, respectively, that characterize charged particle motion in a magnetic field. Their usefulness lies in the fact that they are expressed in more instructive ways than their counterparts: I is equivalent to the path length of the particle motion between two mirror points, whereas L*, although dimensionless, is equivalent to the distance from the center of the Earth to the equatorial point of a given field line, in units of Earth radii, in the simplified case of a dipole magnetic field. However, care should be taken when calculating the above invariants, as the assumption of their conservation is not valid everywhere in the Earth's magnetosphere. This is not clearly stated in state-of-the-art models that are widely used for the calculation of these invariants. The purpose of this work is thus to investigate where in the near-Earth magnetosphere we can safely calculate I and L* with tools with widespread use in the field of space physics, for various magnetospheric conditions and particle initial conditions. More particularly, in this paper we compare the values of I and L* as calculated using LANL*, an artificial neural network developed at the Los Alamos National Laboratory, SPENVIS, a space environment online tool, IRBEM, a software library dedicated to radiation belt modeling, and ptr3D, a 3-D particle tracing code that was developed for this study. We then attempt to quantify the variations between the calculations of I and L* of those models. The deviation between the results given by the models depends on particle initial position, pitch angle and magnetospheric conditions. Using the ptr3D v2.0 particle tracer we map the areas in the Earth's magnetosphere where I and L* can be assumed to be conserved by monitoring the constancy of I for energetic protons propagating forwards and backwards in time. These areas are found to be centered on the noon

  14. A new theory for magnetospheric substorms

    SciTech Connect

    Lyons, L.R.

    1995-10-01

    It is proposed here that the expansion phase of substorms results from a reduction in the large-scale electric field imparted to the magnetosphere from the solar wind, following a {ge} 30-min growth phase due to an enhancement in this electric field. The reduction in the electric field is assumed to propagate antisunward within the magnetosphere. Triggering by a reduction in the electric field is suggested by the observation that substorms are often triggered by northward turnings of the interplanetary magnetic field (IMF). However, under the theory presented here, substorms may be triggered by anything that causes an electric field reduction such as a reduction in the magnitude of the y component of the IMF. A reduction in the large-scale electric field disrupts both the inward motion and energization of plasma sheet particles that occurs during the growth phase. It is suggested here that this can lead to formation of the expansion phase current wedge and active aurora. The current wedge results from the magnetic drift of ions, which has a speed proportional to particle energy, and a large azimuthal gradient in mean particle energy that is expected to develop in the vicinity of magnetic midnight during the growth phase. Current wedge formation will most likely be initiated near the radial distance ({approximately}6-10 R{sub E}) of the peak in the growth phase plasma pressure distribution, and then propagate tailward from that region. Order-of-magnitude calculations show that the above proposal can account for the rapid development of the expansion phase relative to the growth phase, the magnitude of the reduction in the cross-tail current with the current wedge, the speeds of poleward and westward motion of active aurora in the ionosphere, and the magnitude of wedge field-aligned currents that connect the ionospheric region of active auroral to the divergent cross-tail current within the magnetosphere. 77 refs., 9 figs.

  15. Extremely efficient Zevatron in rotating AGN magnetospheres

    NASA Astrophysics Data System (ADS)

    Osmanov, Z.; Mahajan, S.; Machabeli, G.; Chkheidze, N.

    2014-12-01

    A novel model of particle acceleration in the magnetospheres of rotating active galactic nuclei (AGN) is constructed. The particle energies may be boosted up to 1021 eV in a two-step mechanism: in the first stage, the Langmuir waves are centrifugally excited and amplified by means of a parametric process that efficiently pumps rotational energy to excite electrostatic fields. In the second stage, the electrostatic energy is transferred to particle kinetic energy via Landau damping made possible by rapid `Langmuir collapse'. The time-scale for parametric pumping of Langmuir waves turns out to be small compared to the kinematic time-scale, indicating high efficiency of the first process. The second process of `Langmuir collapse' - the creation of caverns or low-density regions - also happens rapidly for the characteristic parameters of the AGN magnetosphere. The Langmuir collapse creates appropriate conditions for transferring electric energy to boost up already high particle energies to much higher values. It is further shown that various energy loss mechanism are relatively weak, and do not impose any significant constraints on maximum achievable energies.

  16. Dynamics of the Earth's Inner Magnetosphere and Its Connection to the Ionosphere: Current Understanding and Challenges

    NASA Technical Reports Server (NTRS)

    Zheng, Yihua

    2011-01-01

    The Earth's inner magnetosphere, a vast volume in space spanning from 1.5 Re (Earth radii) to 10 Re, is a host to a variety of plasma populations (with energy from 1 eV to few MeV) and physical processes where most of which involve plasma and field coupling. As a gigantic particle accelerator, the inner magnetosphere includes three overlapping regions: the plasmasphere, the ring current, and the Van Allen radiation belt. The complex structures and dynamics of these regions are externally driven by solar activities and internally modulated by intricate interactions and coupling. As a major constituent of Space Weather, the inner magnetosphere is both scientifically intriguing and practically important to our society. In this presentation, I will discuss our recent results from the Comprehensive Ring Current Model, in the context of our current understanding of the inner magnetosphere in general and challenges ahead in making further progresses.

  17. Dynamics of the Earth's Inner Magnetosphere and its Connection to the Ionosphere: Current Understanding and Challenges

    NASA Technical Reports Server (NTRS)

    Zheng, Yihua

    2010-01-01

    The Earth's inner magnetosphere, a vast volume in space spanning from 1.5 Re (Earth radii) to 10 Re, is a host to a variety of plasma populations (with energy from 1 eV to few MeV) and physical processes where most of which involve plasma and field coupling. As a gigantic particle accelerator, the inner magnetosphere includes three overlapping regions: the plasmasphere, the ring current, and the Van Allen radiation belt. The complex structures and dynamics of these regions are externally driven by solar activities and internally modulated by intricate interactions and coupling. As a major constituent of Space Weather, the inner magnetosphere is both scientifically intriguing and practically important to our society. In this presentation, I will discuss our recent results from the Comprehensive Ring Current Model, in the context of our current understanding of the inner magnetosphere in general and challenges ahead in making further progresses.

  18. Does Enceladus govern magnetospheric dynamics at Saturn?

    PubMed

    Kivelson, Margaret Galland

    2006-03-10

    Instruments on the Cassini spacecraft reveal that a heat source within Saturn's moon Enceladus powers a great plume of water ice particles and dust grains, a geyser that jets outward from the south polar regions and most likely serves as the dominant source of Saturn's E ring. The interaction of flowing magnetospheric plasma with the plume modifies the particle and field environment of Enceladus. The structure of Saturn's magnetosphere, the extended region of space threaded by magnetic-field lines linked to the planet, is shaped by the ion source at Enceladus, and magnetospheric dynamics may be affected by the rate at which fresh ions are created. PMID:16527963

  19. The earth's magnetosphere. [as astrophysical plasma laboratory

    NASA Technical Reports Server (NTRS)

    Roederer, J. G.

    1974-01-01

    A qualitative description of the general magnetospheric configuration is given, with emphasis on some of the physical processes governing the magnetosphere that are the main targets of current research. The magnetosphere behaves like a huge 'bag' of plasma and radiation that swells and contracts under the influence of the solar wind. The electric field, the magnetospheric plasma, the magnetospheric substorm, and the radiation belt and wave particle interactions are discussed. During the past 15 years, the study of the earth's magnetosphere man's immediate plasma and radiation environment - has undergone a successful stage of discovery and exploration. Investigators have obtained a morphological description of the magnetospheric field, the particle population embedded in it, and its interface with the solar wind, and have identified and are beginning to understand many of the physical processes involved. Quite generally, the magnetosphere reveals itself as a region where it is possible to observe some of the fundamental plasma processes at work that are known to occur elsewhere in the universe.

  20. Magnetospheric electric fields and currents

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Zanetti, L. J.

    1987-01-01

    The progress made in the years 1983-1986 in understanding the character and operation of magnetospheric electric fields and electric currents is discussed, with emphasis placed on the connection with the interior regions. Special attention is given to determinations of global electric-field configurations, measurements of the response of magnetospheric particle populations to the electric-field configurations, and observations of the magnetospheric currents at high altitude and during northward IMF. Global simulations of current distributions are discussed, and the sources of global electric fields and currents are examined. The topics discussed in the area of impulsive and small-scale phenomena include substorm current systems, impulsive electric fields and associated currents, and field-aligned electrodynamics. A key finding of these studies is that the electric fields and currents are interrelated and cannot be viewed as separate entities.

  1. Optically active particles of chiral polymers.

    PubMed

    Song, Ci; Liu, Xuan; Liu, Dong; Ren, Chonglei; Yang, Wantai; Deng, Jianping

    2013-09-01

    Particles constructed by chiral polymers (defined as PCPs) have emerged as a rapidly expanding research field in recent years because of their potentially wide-ranging applications in asymmetric catalysis, enantioselective crystallization, enantioselective release, amongst many others. The particles show considerable optical activity, due to the chirality of the corresponding polymers from which the particles are derived. This review article presents an overview on PCPs with emphasis on our group's recent achievements in the preparation of PCPs derived from optically active helical polymers and their applications. PCPs can be prepared via emulsion polymerization, precipitation polymerization, and suspension polymerization by starting from monomers. Emulsification of preformed chiral polymers and self-assembly approaches also can lead to PCPs. Chiral polymer-based core/shell particles, hollow particles, and magnetic particles are also covered because of their remarkable properties and significant potential applications. PMID:24030962

  2. UT variations of geomagnetic activity as a basis for understanding the magnetic state and dynamics of planetary magnetospheres

    NASA Astrophysics Data System (ADS)

    Kuznetsova, T.; Laptukhov, A.

    This paper deals with the effect of the mutual orientation of the vectors of the dipole magnetic moment, the IMF and the solar wind electric field on the terrestrial magnetosphere in case of the reconnection between the dipole magnetic field and an IMF of arbitrary orientation. Our results can be applied to any magnetosphere, when analyzing the data measured in vicinity of the planets. Results of studies of UT variations of geomagnetic activity are still controversial. We examine the UT variations in Kp index for the period from 1964-1996. We are concerned with not only the UT variation but also how it is controlled by the solar wind and IMF and use the IMF and plasma data for the same period. We attract for the studies a reconnection model elaborated by us. The mo el describes a reconnection betweend the Earth's magnetic field and an IMF of arbitrary orientation taking into account annual and daily motions of the Earth. We use the data to study invariant parameters (independent from a choice of a coordinate system) derived from our model that determine the reconnection. 1)cos(BM), where (BM) is angle between vectors of the IMF B and geomagnetic moment M; 2)vector of electric field of the solar wind E presented by its projections along and across the M vector (Em and Emv). Functional relation of mean Kp-index and cos(BM) is obtained from the analyzed data. The correlation coefficient Cc=0.98 between the data from different years. The Kp has functional dependencies with the parameters Em and Emv too; Cc have the same high values from year to year. These parameters calculated from the data for 33 years taking into account the UT orientation of the vectors show clearly that geomagnetic activity has essential repeated component. Derived functions Kp=F(Emv) and Kp=f(Em) (Kp changes from 0 to 9) show essentially different behavior and differs from the discussed earlier. We use the derived connections for our analysis of the UT course in Kp (daily and annual). Special

  3. Diffusion of torqued active Brownian particles

    NASA Astrophysics Data System (ADS)

    Sevilla, Francisco J.

    An analytical approach is used to study the diffusion of active Brownian particles that move at constant speed in three-dimensional space, under the influence of passive (external) and active (internal) torques. The Smoluchowski equation for the position distribution of the particles is obtained from the Kramer-Fokker-Planck equation corresponding to Langevin equations for active Brownian particles subject to torques. In addition of giving explicit formulas for the mean square-displacement, the non-Gaussian behavior is analyzed through the kurtosis of the position distribution that exhibits an oscillatory behavior in the short-time limit. FJS acknowledges support from PAPIIT-UNAM through the grant IN113114

  4. Interaction of Titan's ionosphere with Saturn's magnetosphere.

    PubMed

    Coates, Andrew J

    2009-02-28

    Titan is the only Moon in the Solar System with a significant permanent atmosphere. Within this nitrogen-methane atmosphere, an ionosphere forms. Titan has no significant magnetic dipole moment, and is usually located inside Saturn's magnetosphere. Atmospheric particles are ionized both by sunlight and by particles from Saturn's magnetosphere, mainly electrons, which reach the top of the atmosphere. So far, the Cassini spacecraft has made over 45 close flybys of Titan, allowing measurements in the ionosphere and the surrounding magnetosphere under different conditions. Here we review how Titan's ionosphere and Saturn's magnetosphere interact, using measurements from Cassini low-energy particle detectors. In particular, we discuss ionization processes and ionospheric photoelectrons, including their effect on ion escape from the ionosphere. We also discuss one of the unexpected discoveries in Titan's ionosphere, the existence of extremely heavy negative ions up to 10000amu at 950km altitude. PMID:19073464

  5. Magnetospheric access of solar particles and the configuration of the distant geomagnetic field, volume 1. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Evans, L. C.

    1972-01-01

    The access of 1.2 to 40 MeV protons and 0.4 to 1.0 MeV electrons from interplanetary space to the polar cap regions was investigated with an experiment on board a low altitude, polar-orbiting satellite (0G0 4). A total of 333 quiet time observations of the electron polar cap boundary give a mapping of the boundary between open and closed geomagnetic field lines. Observations of events associated with co-rotating regions of enhanced proton flux in interplanetary space were used to establish the characteristics of the 1.2 to 40 MeV proton access windows. The results were compared to particle access predictions of the distant geomagnetic tail configurations. The role played by interplanetary anisotropies in the observation of persistent polar cap features is discussed. Special emphasis is given to the problem of nonadiabatic particle entry through regions where the magnetic field is changing direction.

  6. Magnetospheric radio and plasma wave research - 1987-1990

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.

    1991-01-01

    This review covers research performed in the area of magnetospheric plasma waves and wave-particle interactions as well as magnetospheric radio emissions. The report focuses on the near-completion of the discovery phase of radio and plasma wave phenomena in the planetary magnetospheres with the successful completion of the Voyager 2 encounters of Neptune and Uranus. Consideration is given to the advances made in detailed studies and theoretical investigations of radio and plasma wave phenomena in the terrestrial magnetosphere or in magnetospheric plasmas in general.

  7. Velocity distribution in active particles systems

    PubMed Central

    Marconi, Umberto Marini Bettolo; Gnan, Nicoletta; Paoluzzi, Matteo; Maggi, Claudio; Di Leonardo, Roberto

    2016-01-01

    We derive an analytic expression for the distribution of velocities of multiple interacting active particles which we test by numerical simulations. In clear contrast with equilibrium we find that the velocities are coupled to positions. Our model shows that, even for two particles only, the individual velocities display a variance depending on the interparticle separation and the emergence of correlations between the velocities of the particles. When considering systems composed of many particles we find an analytic expression connecting the overall velocity variance to density, at the mean-field level, and to the pair distribution function valid in the limit of small noise correlation times. Finally we discuss the intriguing analogies and main differences between our effective free energy functional and the theoretical scenario proposed so far for phase-separating active particles. PMID:27001289

  8. Velocity distribution in active particles systems

    NASA Astrophysics Data System (ADS)

    Marconi, Umberto Marini Bettolo; Gnan, Nicoletta; Paoluzzi, Matteo; Maggi, Claudio; di Leonardo, Roberto

    2016-03-01

    We derive an analytic expression for the distribution of velocities of multiple interacting active particles which we test by numerical simulations. In clear contrast with equilibrium we find that the velocities are coupled to positions. Our model shows that, even for two particles only, the individual velocities display a variance depending on the interparticle separation and the emergence of correlations between the velocities of the particles. When considering systems composed of many particles we find an analytic expression connecting the overall velocity variance to density, at the mean-field level, and to the pair distribution function valid in the limit of small noise correlation times. Finally we discuss the intriguing analogies and main differences between our effective free energy functional and the theoretical scenario proposed so far for phase-separating active particles.

  9. Particle emission factors during cooking activities

    NASA Astrophysics Data System (ADS)

    Buonanno, G.; Morawska, L.; Stabile, L.

    Exposure to particles emitted by cooking activities may be responsible for a variety of respiratory health effects. However, the relationship between these exposures and their subsequent effects on health cannot be evaluated without understanding the properties of the emitted aerosol or the main parameters that influence particle emissions during cooking. Whilst traffic-related emissions, stack emissions and concentrations of ultrafine particles (UFPs, diameter < 100 nm) in urban ambient air have been widely investigated for many years, indoor exposure to UFPs is a relatively new field and in order to evaluate indoor UFP emissions accurately, it is vital to improve scientific understanding of the main parameters that influence particle number, surface area and mass emissions. The main purpose of this study was to characterise the particle emissions produced during grilling and frying as a function of the food, source, cooking temperature and type of oil. Emission factors, along with particle number concentrations and size distributions were determined in the size range 0.006-20 μm using a Scanning Mobility Particle Sizer (SMPS) and an Aerodynamic Particle Sizer (APS). An infrared camera was used to measure the temperature field. Overall, increased emission factors were observed to be a function of increased cooking temperatures. Cooking fatty foods also produced higher particle emission factors than vegetables, mainly in terms of mass concentration, and particle emission factors also varied significantly according to the type of oil used.

  10. Magnetospheric Science Objectives of the Juno Mission

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; Adriani, A.; Allegrini, F.; Bolton, S. J.; Bonfond, B.; Bunce, E. J.; Connerney, J. E. P.; Cowley, S. W. H.; Ebert, R. W.; Gladstone, G. R.; Hansen, C. J.; Kurth, W. S.; Levin, S. M.; Mauk, B. H.; McComas, D. J.; Paranicas, C. P.; Santos-Costa, D.; Thorne, R. M.; Valek, P.; Waite, J. H.; Zarka, P.

    2014-02-01

    In July 2016, NASA's Juno mission becomes the first spacecraft to enter polar orbit of Jupiter and venture deep into unexplored polar territories of the magnetosphere. Focusing on these polar regions, we review current understanding of the structure and dynamics of the magnetosphere and summarize the outstanding issues. The Juno mission profile involves (a) a several-week approach from the dawn side of Jupiter's magnetosphere, with an orbit-insertion maneuver on July 6, 2016; (b) a 107-day capture orbit, also on the dawn flank; and (c) a series of thirty 11-day science orbits with the spacecraft flying over Jupiter's poles and ducking under the radiation belts. We show how Juno's view of the magnetosphere evolves over the year of science orbits. The Juno spacecraft carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter's radiation belts. We summarize how these Juno measurements address issues of auroral processes, microphysical plasma physics, ionosphere-magnetosphere and satellite-magnetosphere coupling, sources and sinks of plasma, the radiation belts, and the dynamics of the outer magnetosphere. To reach Jupiter, the Juno spacecraft passed close to the Earth on October 9, 2013, gaining the necessary energy to get to Jupiter. The Earth flyby provided an opportunity to test Juno's instrumentation as well as take scientific data in the terrestrial magnetosphere, in conjunction with ground-based and Earth-orbiting assets.

  11. Observing Dynamics in Large-Scale Birkeland Currents with the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE)

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Korth, H.; Waters, C. L.; Barnes, R. J.; Olson, C.

    2015-12-01

    The Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) provides continuous global observations of the magnetic perturbations that predominantly reflect Birkeland currents. The data are acquired by avionics magnetometers of the Iridium satellites and allow measurements from 66 satellites in near-polar circular, low altitude orbits. The configuration of the Iridium satellite constellation determines the longitude sampling spacing of ~ 2 hours and the re-sampling cadence of the system which is 9 minutes. From 2008 to 2013 the AMPERE system was developed which included new flight software on the Iridium satellites to allow telemetry of higher rate data to the ground and the Science Data Center to derive Birkeland current perturbations from the data and invert these signals to derive the global distributions of the currents using data windows of ten minutes. There were many challenges in developing AMPERE including automating inter-calibration between satellites and the baseline determination and removals. The results of AMPERE provide stunning confirmation of many of the statistical estimates for the distribution of currents but more significantly open a new window to understand their instantaneous distribution and dynamics. Examples of new features of the currents and their dynamics revealed by AMPERE are presented. In addition, prospects for new data products and increased data quality anticipated from AMPERE-NEXT to be implemented on the Iridium-NEXT generation of satellites are discussed.

  12. The Properties of Large Amplitude Whistler Mode Waves in the Magnetosphere: Propagation and Relationship with Geomagnetic Activity

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Wygant, J. R.; Goetz, K.; Breneman, A.; Kersten, K.

    2011-01-01

    Wepresent resultsof a studyof the characteristicsof very large amplitude whistler mode waves inside the terrestrial magnetosphere at radial distances of less than 15 RE using waveform capture data from the Wind spacecraft. We observed 247 whistler mode waves with at least one electric field component (105/247 had !80 mV/m peak!to!peak amplitudes) and 66 whistler mode waves with at least one search coil magnetic field component (38/66 had !0.8 nT peak!to!peak amplitudes). Wave vectors determined from events with three magnetic field components indicate that 30/46 propagate within 20 of the ambient magnetic field, though some are more oblique (up to "50 ). No relationship was observed between wave normal angle and GSM latitude. 162/247 of the large amplitude whistler mode waves were observed during magnetically active periods (AE > 200 nT). 217 out of 247 total whistler mode waves examined were observed inside the radiation belts. We present a waveform capture with the largest whistler wave magnetic field amplitude (^8 nT peak!to!peak) ever reported in the radiation belts. The estimated Poynting flux magnitude associated with this wave is ^300 mW/m2, roughly four orders of magnitude above estimates from previous satellite measurements. Such large Poynting flux values are consistent with rapid energization of electrons.

  13. Space weather models for radiation conditions outside and inside of the Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Nymmik, Rikho; Kalegaev, Vladimir; Panasyuk, Mikhail

    2016-07-01

    Radiation environment in the Earth magnetosphere can not be considered without taking into account the physical conditions in interplanetary space due to solar activity. Therefore, any realistic model of radiation inside the magnetosphere should take into account the physical condition determined by the models out of it. Since the flux of galactic and solar cosmic rays in the magnetosphere based on the model of radiation outside the magnetosphere with an indispensable view of the magnetic field of the Earth, due to changes in the solar wind, interplanetary shock waves and magnetic field. These factors are also influence the models of trapped radiation and circular current. Particularly, this report addressed to the methodological issues of generalization of experimental data to the level of computational models, which is unchanged properties of predicting all kinds of extreme situations. The complex of these problems has long been discussed under the pressure of public attention in connection with the problems of weather forecasting and hydrology. In the field of space weather the problem of operational models evaluation (so called "metric & validation" activity) is also of great interest now. In the light of changes in the factors of solar activity in the last minimum and in the solar cycle 24, the report discusses the problems of modeling particle fluxes outside the magnetosphere. Current status of near- Earth radiation modeling including radiation belt particles transport, acceleration and losses will be discussed as well from the experimental and theoretical viewpoint.

  14. Satellites of Uranus control its magnetosphere

    SciTech Connect

    Cheng, A.F.; Hill, T.W.

    1984-10-01

    The importance of the satellites of Uranus as sources of magnetospheric plasma were investigated. It is found that neither an Io like plasma source nor a Titan like source is likely at Uranus. The likely presence of a heavy ion plasma torus maintained by charged particle sputtering of the icy satellites is examined. Sputtering of Saturn's icy satellites is considered an important source of heavy ion (oxygen) plasma in Saturn's inner magnetosphere. A major unresolved question is whether this sputtering process does depend on the preexistence of magnetospheric heavy ions derived from another source, Titian.

  15. Fluctuating neutron star magnetosphere: braking indices of eight pulsars, frequency second derivatives of 222 pulsars and 15 magnetars

    NASA Astrophysics Data System (ADS)

    Ou, Z. W.; Tong, H.; Kou, F. F.; Ding, G. Q.

    2016-04-01

    Eight pulsars have low braking indices, which challenge the magnetic dipole braking of pulsars. 222 pulsars and 15 magnetars have abnormal distribution of frequency second derivatives, which also make contradiction with classical understanding. How neutron star magnetospheric activities affect these two phenomena are investigated by using the wind braking model of pulsars. It is based on the observational evidence that pulsar timing is correlated with emission and both aspects reflect the magnetospheric activities. Fluctuations are unavoidable for a physical neutron star magnetosphere. Young pulsars have meaningful braking indices, while old pulsars' and magnetars' fluctuation item dominates their frequency second derivatives. It can explain both the braking index and frequency second derivative of pulsars uniformly. The braking indices of eight pulsars are the combined effect of magnetic dipole radiation and particle wind. During the lifetime of a pulsar, its braking index will evolve from three to one. Pulsars with low braking index may put strong constraint on the particle acceleration process in the neutron star magnetosphere. The effect of pulsar death should be considered during the long term rotational evolution of pulsars. An equation like the Langevin equation for Brownian motion was derived for pulsar spin-down. The fluctuation in the neutron star magnetosphere can be either periodic or random, which result in anomalous frequency second derivative and they have similar results. The magnetospheric activities of magnetars are always stronger than those of normal pulsars.

  16. A Massively Parallel Particle Code for Rarefied Ionized and Neutral Gas Flows in Earth and Planetary Atmospheres, Ionospheres and Magnetospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.

    2004-01-01

    In order to understand the global structure, dynamics, and physical and chemical processes occurring in the upper atmospheres, exospheres, and ionospheres of the Earth, the other planets, comets and planetary satellites and their interactions with their outer particles and fields environs, it is often necessary to address the fundamentally non-equilibrium aspects of the physical environment. These are regions where complex chemistry, energetics, and electromagnetic field influences are important. Traditional approaches are based largely on hydrodynamic or magnetohydrodynamic MHD) formulations and are very important and highly useful. However, these methods often have limitations in rarefied physical regimes where the molecular collision rates and ion gyrofrequencies are small and where interactions with ionospheres and upper neutral atmospheres are important.

  17. Magnetospheres: Jupiter, Satellite Interactions

    NASA Astrophysics Data System (ADS)

    Neubauer, F.; Murdin, P.

    2000-11-01

    Most of the satellites of Jupiter, notably the large Galilean satellites Io, Europa, Ganymede and Callisto (see JUPITER: SATELLITES), orbit deep inside the magnetosphere of Jupiter (see JUPITER: MAGNETOSPHERE) and are therefore immersed in the flow of magnetospheric plasma (made of a mixture of electrons and ions) and subjected to an interaction with the strong Jovian magnetic field. These intera...

  18. ULF Waves in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Takahashi, K.

    2016-02-01

    This chapter presents examples that illustrate how recent spacecraft observations allow us to quantitatively understand the mode structure of various magnetohydrodynamic (MHD)-type ultra-low-frequency (ULF) waves propagating into or excited in the inner magnetosphere. In addition, particle observations provide evidence for specific types of wave-particle interaction. The fast mode waves may be free propagating or evanescent, depending on their frequency and wavelength and the spatial variation of the MHD wave speed. The inhomogeneity of the magnetosphere causes the fast mode energy to be transferred to standing Alfven waves through the well-known field line resonance mechanism. The cold plasma MHD equation for axisymmetric plasma with a dipole magnetic field yields two guided mode solutions called the axisymmetric toroidal mode and guided poloidal mode. Although toroidal and poloidal modes are always coupled in the real magnetosphere, the idealized modes are good approximation to the basic features of observed magnetospheric standing Alfven waves.

  19. MESSENGER Observations of Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2010-01-01

    During MESSENGER's second and third flybys of Mercury on October 6, 2008 and September 29, 2009, respectively, southward interplanetary magnetic field (IMF) produced intense reconnection signatures in the dayside and nightside magnetosphere and markedly different system-level responses. The IMF during the second flyby was continuously southward and the magnetosphere appeared very active, with large magnetic field components normal to the magnetopause and the generation of flux transfer events at the magnetopause and plasmoids in the tail current sheet every 30 to 90 s. However, the strength and direction of the tail magnetic field was stable. In contrast, the IMF during the third flyby varied from north to south on timescales of minutes. Although the MESSENGER measurements were limited during that encounter to the nightside magnetosphere, numerous examples of plasmoid release in the tail were detected, but they were not periodic. Instead, plasmoid release was highly correlated with four large enhancements of the tail magnetic field (i.e. by factors > 2) with durations of approx. 2 - 3 min. The increased flaring of the magnetic field during these intervals indicates that the enhancements were caused by loading of the tail with magnetic flux transferred from the dayside magnetosphere. New analyses of the second and third flyby observations of reconnection and its system-level effects provide a basis for comparison and contrast with what is known about the response of the Earth s magnetosphere to variable versus steady southward IMF.

  20. Recovery phase of magnetospheric substorms and its association with morning-sector aurora

    SciTech Connect

    Opgenoorth, H.J.; Persson, M.A.L.; Pulkkinen, T.I.; Pellinen, R.J.

    1994-03-01

    The authors report on conclusions drawn from an extensive study of ground based measurements of the recovery phase of magnetospheric substorms. Much previous work has considered this phase to simply consist of decay processes of growth phase phenomena as the magnetosphere relaxes to its quiescent state. From their studies of observational data the authors conclude that there is evidence of distinct processes within the recovery phase which are related to it alone. These include intense electrojet activity, high-energy particle precipitation, distinct large scale auroral phenomena, and possibly even expanded auroral activity.

  1. Collective surfing of chemically active particles.

    PubMed

    Masoud, Hassan; Shelley, Michael J

    2014-03-28

    We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures. PMID:24724685

  2. Collective Surfing of Chemically Active Particles

    NASA Astrophysics Data System (ADS)

    Masoud, Hassan; Shelley, Michael J.

    2014-03-01

    We study theoretically the collective dynamics of immotile particles bound to a 2D surface atop a 3D fluid layer. These particles are chemically active and produce a chemical concentration field that creates surface-tension gradients along the surface. The resultant Marangoni stresses create flows that carry the particles, possibly concentrating them. For a 3D diffusion-dominated concentration field and Stokesian fluid we show that the surface dynamics of active particle density can be determined using nonlocal 2D surface operators. Remarkably, we also show that for both deep or shallow fluid layers this surface dynamics reduces to the 2D Keller-Segel model for the collective chemotactic aggregation of slime mold colonies. Mathematical analysis has established that the Keller-Segel model can yield finite-time, finite-mass concentration singularities. We show that such singular behavior occurs in our finite-depth system, and study the associated 3D flow structures.

  3. Juno Magnetometer Observations in the Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Connerney, J. E.; Oliversen, R. J.; Espley, J. R.; MacDowall, R. J.; Schnurr, R.; Sheppard, D.; Odom, J.; Lawton, P.; Murphy, S.; Joergensen, J. L.; Joergensen, P. S.; Merayo, J. M.; Denver, T.; Bloxham, J.; Smith, E. J.; Murphy, N.

    2013-12-01

    The Juno spacecraft enjoyed a close encounter with Earth on October 9, 2013, en route to Jupiter Orbit Insertion (JOI) on July 5, 2016. The Earth Flyby (EFB) provided a unique opportunity for the Juno particles and fields instruments to sample mission relevant environments and exercise operations anticipated for orbital operations at Jupiter, particularly the period of intense activity around perijove. The magnetic field investigation onboard Juno is equipped with two magnetometer sensor suites, located at 10 and 12 m from the spacecraft body at the end of one of the three solar panel wings. Each contains a vector fluxgate magnetometer (FGM) sensor and a pair of co-located non-magnetic star tracker camera heads which provide accurate attitude determination for the FGM sensors. This very capable magnetic observatory sampled the Earth's magnetic field at 64 vector samples/second throughout passage through the Earth's magnetosphere. We present observations of the Earth's magnetic field and magnetosphere obtained throughout the encounter and compare these observations with those of other Earth-orbiting assets, as available, and with particles and fields observations acquired by other Juno instruments operated during EFB.

  4. A boundary layer model for magnetospheric substorms

    NASA Technical Reports Server (NTRS)

    Rostoker, Gordon; Eastman, Tim

    1987-01-01

    An alternative framework for understanding magnetospheric substorm activity is presented. It is argued that observations of magnetic field and plasma flow variations in the magnetotail can be explained in terms of the passage of the plasma sheet boundary layer over the satellite detecting the tail signatures. It is shown that field-aligned currents and particle acceleration processes on magnetic field lines threading the ionospheric Harang discontinuity lead to the distinctive particle and field signatures observed in the magnetotail during substorms. It is demonstrated that edge effects of field-aligned currents associated with the westward traveling surge can lead to the negative B(z) perturbations observed in the tail that are presently attributed to observations made on the anti-earthward side of a near-earth neutral line. Finally, it is shown that the model can provide a physical explanation of both the driven system and the loading-unloading system whose combined effects provide the observed substorm perturbation pattern in the magnetosphere and ionosphere.

  5. Convective motion and the structure of the Jupiter magnetosphere

    NASA Technical Reports Server (NTRS)

    Sakurai, K.

    1971-01-01

    The convective motion and its relation to the electric field in the magnetosphere of Jupiter are investigated. It is shown that the electric field is induced in the Jovian ionosphere due to the corotating action of the ionospheric gases and further is communicated into the magnetosphere along the magnetic lines of force which connect between the ionosphere and the magnetosphere. This electric field drives the plasma to corotate with the planet in the magnetosphere. The distribution of the electric field and its effect on the plasma motion is estimated in the magnetosphere. The shape of the magnetosphere is then estimated considering the equilibrium condition. Discussion is given on the equilibrium plasma distribution in the magnetosphere and on the condition for the excitation of wave-particle interaction at the Io orbit.

  6. The Parameterization of Top-Hat Particle Sensors with Microchannel-Plate-Based Detection Systems and its Application to the Fast Plasma Investigation on NASA's Magnetospheric MultiScale Mission

    NASA Technical Reports Server (NTRS)

    Gershman, Daniel J.; Gliese, Ulrik; Dorelli, John C.; Avanov, Levon A.; Barrie, Alexander C.; Chornay, Dennis J.; MacDonald, Elizabeth A.; Holland, Matthew P.; Pollock, Craig J.

    2015-01-01

    The most common instrument for low energy plasmas consists of a top-hat electrostatic analyzer geometry coupled with a microchannel-plate (MCP)-based detection system. While the electrostatic optics for such sensors are readily simulated and parameterized during the laboratory calibration process, the detection system is often less well characterized. Furthermore, due to finite resources, for large sensor suites such as the Fast Plasma Investigation (FPI) on NASA's Magnetospheric Multiscale (MMS) mission, calibration data are increasingly sparse. Measurements must be interpolated and extrapolated to understand instrument behavior for untestable operating modes and yet sensor inter-calibration is critical to mission success. To characterize instruments from a minimal set of parameters we have developed the first comprehensive mathematical description of both sensor electrostatic optics and particle detection systems. We include effects of MCP efficiency, gain, scattering, capacitive crosstalk, and charge cloud spreading at the detector output. Our parameterization enables the interpolation and extrapolation of instrument response to all relevant particle energies, detector high voltage settings, and polar angles from a small set of calibration data. We apply this model to the 32 sensor heads in the Dual Electron Sensor (DES) and 32 sensor heads in the Dual Ion Sensor (DIS) instruments on the 4 MMS observatories and use least squares fitting of calibration data to extract all key instrument parameters. Parameters that will evolve in flight, namely MCP gain, will be determined daily through application of this model to specifically tailored in-flight calibration activities, providing a robust characterization of sensor suite performance throughout mission lifetime. Beyond FPI, our model provides a valuable framework for the simulation and evaluation of future detection system designs and can be used to maximize instrument understanding with minimal calibration

  7. Magnetospheric MultiScale (MMS) System Manager

    NASA Technical Reports Server (NTRS)

    Schiff, Conrad; Maher, Francis Alfred; Henely, Sean Philip; Rand, David

    2014-01-01

    The Magnetospheric MultiScale (MMS) mission is an ambitious NASA space science mission in which 4 spacecraft are flown in tight formation about a highly elliptical orbit. Each spacecraft has multiple instruments that measure particle and field compositions in the Earths magnetosphere. By controlling the members relative motion, MMS can distinguish temporal and spatial fluctuations in a way that a single spacecraft cannot.To achieve this control, 2 sets of four maneuvers, distributed evenly across the spacecraft must be performed approximately every 14 days. Performing a single maneuver on an individual spacecraft is usually labor intensive and the complexity becomes clearly increases with four. As a result, the MMS flight dynamics team turned to the System Manager to put the routine or error-prone under machine control freeing the analysts for activities that require human judgment.The System Manager is an expert system that is capable of handling operations activities associated with performing MMS maneuvers. As an expert system, it can work off a known schedule, launching jobs based on a one-time occurrence or on a set reoccurring schedule. It is also able to detect situational changes and use event-driven programming to change schedules, adapt activities, or call for help.

  8. In situ magnetic field measurements during AMPTE solar wind Li(+) releases. [Active Magnetospheric Particle Tracer Explorers

    NASA Technical Reports Server (NTRS)

    Luehr, H.; Kloecker, N.; Southwood, D. J.; Acuna, M.; Haeusler, B.

    1986-01-01

    The effects of lithium ion releases on solar wind flow are investigated. The background field conditions during the releases on September 11 and 20, 1984 are discussed. The magnetic field data recorded by the Ion Release Module and United Kingdom Satellite are described. It is observed that the first release occurred on the field lines connecting to the earth's bow shock causing difficulty in separating the effects of natural large scale perturbations from the ion effects. In the second release, which occurred in a stable, ambient environment, the characteristics of a Venus-like perturbation of the magnetic field are detected. It is concluded that in both releases a field cavity is formed, the field transverse to the solar wind flow is amplified, and the transverse component is compressed.

  9. Millisecond time scale atmospheric light pulses associated with solar and magnetospheric activity.

    NASA Technical Reports Server (NTRS)

    Ogelman, H.

    1973-01-01

    By using a wide-angle photomultiplier system a class of millisecond time scale diffuse atmospheric light emission of terrestrial origin has been discovered. These fast atmospheric pulsation events also show damped oscillations around 10-kHz frequency, which distinguishes them from ordinary lightning-type events. Evidence is presented for the enhancement in the rate of these events induced by solar flare activity.

  10. Magnetospheric convection pattern and its implications

    NASA Technical Reports Server (NTRS)

    Zhu, Xiaoming

    1993-01-01

    When we use 14 months of the Fast Plasma Experiment ion velocity measurements, the mean magnetospheric circulation pattern is constructed. It is shown that the magnetospheric convection velocity is of the order tens of kilometers per second. The convection is largely restricted to the outer magnetosphere. During magnetically active periods the convection velocity increases and the convection boundary extends to the region closer to the Earth, indicating more magnetic field flux is being transported to the dayside magnetosphere. It is also shown that the convective flows tend to follow contours of constant unit flux volume as they move around the Earth, especially on the duskside of the magnetosphere. This helps to avoid the pressure balance inconsistency often found in two-dimensional magnetotail models.

  11. Are steady magnetospheric convection events prolonged substorms?

    NASA Astrophysics Data System (ADS)

    Walach, M.-T.; Milan, S. E.

    2015-03-01

    Magnetospheric modes, including substorms, sawtooth events, and steady magnetospheric convection events, have in the past been described as different responses of the magnetosphere to coupling with the solar wind. Using previously determined event lists for sawtooth events, steady magnetospheric convection events, and substorms, we produce a statistical study of these event types to examine their similarities and behavior in terms of solar wind parameters, auroral brightness, open magnetospheric flux, and geomagnetic indices. A superposed epoch analysis shows that individual sawteeth show the same signatures as substorms but occur during more extreme cases of solar wind driving as well as geomagnetic activity. We also explore the limitations of current methods of identifying steady magnetospheric convection events and explain why some of those events are flagged inappropriately. We show that 58% of the steady magnetospheric convection events considered, as identified by criteria defined in previous studies are part of a prolonged version of substorms due to continued dayside driving during expansion phase. The remaining 42% are episodes of enhanced magnetospheric convection, occurring after extended periods of dayside driving.

  12. Magnetospheric equilibrium with anisotropic pressure

    SciTech Connect

    Cheng, C.Z.

    1991-07-01

    Self-consistent magnetospheric equilibrium with anisotropic pressure is obtained by employing an iterative metric method for solving the inverse equilibrium equation in an optimal flux coordinate system. A method of determining plasma parallel and perpendicular pressures from either analytic particle distribution or particle distribution measured along the satellite's path is presented. The numerical results of axisymmetric magnetospheric equilibrium including the effects of finite beta, pressure anisotropy, and boundary conditions are presented for a bi-Maxwellian particle distribution. For the isotropic pressure cases, the finite beta effect produces an outward expansion of the constant magnetic flux surfaces in relation to the dipole field lines, and along the magnetic field the toroidal ring current is maximum at the magnetic equator. The effect of pressure anisotropy is found to further expand the flux surfaces outward. Along the magnetic field lines the westward ring current can be peak away from the equator due to an eastward current contribution resulting from pressure anisotropy. As pressure anisotropy increases, the peak westward current can become more singular. The outer boundary flux surface has significant effect on the magnetospheric equilibrium. For the outer flux boundary resembling dayside compressed flux surface due to solar wind pressure, the deformation of the magnetic field can be quite different from that for the outer flux boundary resembling the tail-like surface. 23 refs., 17 figs.

  13. Magnetospheric equilibrium with anisotropic pressure

    SciTech Connect

    Cheng, C.Z. )

    1992-02-01

    Self-consistent magnetospheric equilibria with anisotropic pressure are obtained by employing an iterative metric method for solving the inverse equilibrium equation in an optimal flux coordinate system. A method of determining plasma parallel and perpendicular pressures from either analytic particle distributions or particle distributions measured along a satellite's path is presented. The numerical results of axisymmetric magnetospheric equilibria including the effects of finite beta, pressure anisotropy, and boundary conditions are presented for a bi-Maxwellian particle distribution. For the isotropic pressure cases the finite beta effect produces an outward expansion of the constant magnetic flux surfaces in relation to the dipole field lines, and along the magnetic field the toroidal ring current is maximum at the magnetic equator. The effect of pressure anisotropy is found to further expand the flux surfaces outward. Along the magnetic field lines the westward ring current can be peak away from the equator owing to an eastward current contribution resulting from pressure anisotropy. As pressure anisotropy increases, the peak westward current can become more singular. The outer boundary flux surface has a significant effect on the magnetospheric equilibrium. For the outer flux boundary resembling the dayside compressed flux surface due to solar wind pressure, the deformation of the magnetic field can be quite different from that for the outer flux boundary resembling the taillike flux surface.

  14. Energy flux in the Earth's magnetosphere: Storm substorm relationship

    NASA Astrophysics Data System (ADS)

    Alexeev, Igor I.

    2003-04-01

    Three ways of the energy transfer in the Earth's magnetosphere are studied. The solar wind MHD generator is an unique energy source for all magnetospheric processes. Field-aligned currents directly transport the energy and momentum of the solar wind plasma to the Earth's ionosphere. The magnetospheric lobe and plasma sheet convection generated by the solar wind is another magnetospheric energy source. Plasma sheet particles and cold ionospheric polar wind ions are accelerated by convection electric field. After energetic particle precipitation into the upper atmosphere the solar wind energy is transferred into the ionosphere and atmosphere. This way of the energy transfer can include the tail lobe magnetic field energy storage connected with the increase of the tail current during the southward IMF. After that the magnetospheric substorm occurs. The model calculations of the magnetospheric energy give possibility to determine the ground state of the magnetosphere, and to calculate relative contributions of the tail current, ring current and field-aligned currents to the magnetospheric energy. The magnetospheric substorms and storms manifest that the permanent solar wind energy transfer ways are not enough for the covering of the solar wind energy input into the magnetosphere. Nonlinear explosive processes are necessary for the energy transmission into the ionosphere and atmosphere. For understanding a relation between substorm and storm it is necessary to take into account that they are the concurrent energy transferring ways.

  15. The sodium exosphere and magnetosphere of Mercury

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.

    1986-05-01

    Following the recent optical discovery of intense sodium D-line emission from Mercury, the scenario of an extended exosphere of sodium and other metallic atoms is explored. It is shown that the strong effect of solar radiation pressure acceleration would permit the escape of Na atoms from Mercury's surface even if they are ejected at a velocity lower than the surface escape velocity. Fast photoionization of the Na atoms is effective in limiting the tailward extension of the sodium exosphere, however. The subsequent loss of the photoions to the magnetosphere could be a significant source of the magnetospheric plasma. The recirculation of the magnetospheric charged particles to the planetary surface could also play an important role in maintaining an extended sodium exosphere as well as a magnetosphere of sputtered metallic ions.

  16. Ion trajectories in Mercury s magnetosphere

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Killen, R.; Reiff, P.

    The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere obtained by the Toffoletto-Hill (JGR 98, 1339, 1993) model of an open magnetosphere, and supplement it with the Ding et al. (Phys. Space Plasmas, 1996) potential solver to represent the convection electric field. We calculate the fractional escape ratio of Na and K ions as a function of IMF direction and magnitude. We also provide evidence for the role that the IMF may play in generating ions at Mercury by quantitatively predicting the solar wind particle flux that directly impinges upon the Hermean surface as w e regulate the IMF environment.

  17. Reciprocating motion of active deformable particles

    NASA Astrophysics Data System (ADS)

    Tarama, M.; Ohta, T.

    2016-05-01

    Reciprocating motion of an active deformable particle in a homogeneous medium is studied theoretically. For generality, we employ a simple model derived from symmetry considerations for the center-of-mass velocity and elliptical and triangular deformations in two dimensions. We carry out, for the first time, a systematic investigation of the reciprocating motion of a self-propelled particle. It is clarified that spontaneous breaking of the front-rear asymmetry is essential for the reciprocating motion. Moreover, two routes are found for the formation of the reciprocating motion. One is a bifurcation from a motionless stationary state. The other is destabilisation of an oscillatory rectilinear motion.

  18. Radiation hazards on space missions outside the magnetosphere.

    PubMed

    Letaw, J R; Silberberg, R; Tsao, C H

    1989-01-01

    Future space missions outside the magnetosphere will subject astronauts to a hostile and unfamiliar radiation environment. An annual dose equivalent to the blood-forming organs (BFOs) of approximately 0.5 Sv is expected, mostly from heavy ions in the galactic cosmic radiation. On long-duration missions, an anomalously-large solar energetic particle event may occur. Such an event can expose astronauts to up to approximately 25 Gy (skin dose) and up to approximately 2 Sv (BFO dose) with no shielding. The anticipated radiation exposure may necessitate spacecraft design concessions and some restriction of mission activities. In this paper we discuss our model calculations of radiation doses in several exo-magnetospheric environments. Specific radiation shielding strategies are discussed. A new calculation of aluminum equivalents of potential spacecraft shielding materials demonstrates the importance of low-atomic-mass species for protection from galactic cosmic radiation. PMID:11537305

  19. Magnetospheric Multiscale (MMS) Orbit

    NASA Video Gallery

    This animation shows the orbits of Magnetospheric Multiscale (MMS) mission, a Solar-Terrestrial Probe mission comprising of four identically instrumented spacecraft that will study the Earth's magn...

  20. First-Principles Simulations of Pulsar Magnetospheres

    NASA Astrophysics Data System (ADS)

    Spitkovsky, Anatoly

    Pulsars are rotating magnetized neutron stars that produce broadband, pulsed emission. Observations with Fermi Gamma-ray Space Telescope have uncovered more than 100 gamma-ray emitting pulsars, dramatically expanding the number of such sources known, and producing unprecedented data on light curves and spectra in the gamma-ray band. The magnetospheric processes that lead to this emission are very interesting and currently not understood in detail. The main difficulty is the absence of a self-consistent model of the pulsar magnetosphere that can predict the global shape of the magnetic field and the state of the plasma throughout the magnetosphere. The standard picture envisions the magnetosphere as filled with plasma due to space-charge-limited flow of charges from the surface of the star. These charges are accelerated by strong electric fields induced by rapid stellar rotation. As charges are curved while traveling along the magnetic fields, they emit curvature radiation that can pair-produce and fill the magnetosphere with pair plasma. The currents and charges in this plasma affect magnetic field structure and particle acceleration. Until recently, no self-consistent solutions of the pulsar electrodynamics that accounted for plasma supply and production existed. Considerable progress on the global magnetospheric structure was made under assumptions about the plasma supply in the force-free and magnetohydrodynamic limits, which assume abundant plasma throughout the magnetosphere. These solutions allowed to calculate the global structure of oblique rotators and their spin-down power at the expense of losing information about particle density and acceleration, and making it difficult to compute emission spectra. Recently, the development of multidimensional kinetic simulations has brought the goal of self-consistently calculating plasma supply and magnetospheric shape of pulsars closer to reality. In this proposal, we plan to perform first three-dimensional kinetic

  1. Charged dust in the earth's magnetosphere.

    NASA Astrophysics Data System (ADS)

    Horanyi, M.

    Computer simulations were carried out on the spatial distribution of small Al2O3 particles dumped into the Earth's magnetosphere during solid rocket propellant burns. In addition to the standard gravitational and light pressure forces, the author has taken into account the electrodynamic forces as the particle will be electrostatically charged because it is immersed in the plasma and radiative environment of the Earth.The author concludes that the lifetime of a grain in the magnetosphere is not sensitive to the electrodynamic forces but the number of grains lost to the solar wind will dramatically increase at the expense of the flux lost by colliding with the Earth.

  2. Temperature (de)activated patchy colloidal particles

    NASA Astrophysics Data System (ADS)

    de las Heras, Daniel; Telo da Gama, Margarida M.

    2016-06-01

    We present a new model of patchy particles in which the interaction sites can be activated or deactivated by varying the temperature of the system. We study the thermodynamics of the system by means of Wertheim’s first order perturbation theory, and use Flory–Stockmayer theory of polymerization to analyse the percolation threshold. We find a very rich phase behaviour including lower critical points and reentrant percolation.

  3. Temperature (de)activated patchy colloidal particles.

    PubMed

    de Las Heras, Daniel; da Gama, Margarida M Telo

    2016-06-22

    We present a new model of patchy particles in which the interaction sites can be activated or deactivated by varying the temperature of the system. We study the thermodynamics of the system by means of Wertheim's first order perturbation theory, and use Flory-Stockmayer theory of polymerization to analyse the percolation threshold. We find a very rich phase behaviour including lower critical points and reentrant percolation. PMID:27115118

  4. Does Saturn's Magnetosphere Feel the Presence of Titan?

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Johnson, R. E.; Rymer, A. M.; Woodson, A.; Mitchell, D. G.

    2014-12-01

    Saturn's largest moon, Titan, has been the topic of much interest and mystery. This satellite is the second largest moon in the solar system and is even larger than the planet Mercury. It has a dense, nitrogen-rich atmosphere and no intrinsic magnetic field. Thus, it was believed that as Titan orbits in Saturn's outer magnetosphere it serves as the primary source of heavy magnetospheric particles assumed to be dominated by nitrogen. However, HST observations and the last 10 years of Cassini data have revealed that cryogenic plumes from the tiny moon, Enceladus, actually provide the majority of heavy magnetospheric particles which are water-group in composition. Therefore, Titan was demoted to having a relatively minor impact on Saturn's magnetosphere. However, as more observations become available, it is becoming increasingly more difficult to explain all of the magnetospheric nitrogen observations as originating from Enceladus. For this talk, we review previous observations and findings and then present recent results based on Cassini CAPS and MIMI charged particle observations. We combine these data with modeling to examine the relative impact of Titan in generating magnetospheric particle populations as well as examining outer magnetospheric plasma conditions along Titan's orbit and during encounters. These further results appear to suggest that Titan may actually be a much more significant component of Saturn's magnetosphere.

  5. Global simulations of the three-dimensional magnetosphere

    NASA Technical Reports Server (NTRS)

    Leboeuf, J. N.; Tajima, T.; Kennel, C. F.; Dawson, J. M.

    1981-01-01

    Global three-dimensional computer simulations of the magnetosphere using a particle MHD code, reproduce the steady-state Dungey magnetospheric topology in three dimensions. The formation of a compression zone downstream of the tail neutral line that is probably bounded by wake shocks is observed. This compression zone changes its cross-section with distance downstream.

  6. Collective dynamics of soft active particles.

    PubMed

    van Drongelen, Ruben; Pal, Anshuman; Goodrich, Carl P; Idema, Timon

    2015-03-01

    We present a model of soft active particles that leads to a rich array of collective behavior found also in dense biological swarms of bacteria and other unicellular organisms. Our model uses only local interactions, such as Vicsek-type nearest-neighbor alignment, short-range repulsion, and a local boundary term. Changing the relative strength of these interactions leads to migrating swarms, rotating swarms, and jammed swarms, as well as swarms that exhibit run-and-tumble motion, alternating between migration and either rotating or jammed states. Interestingly, although a migrating swarm moves slower than an individual particle, the diffusion constant can be up to three orders of magnitude larger, suggesting that collective motion can be highly advantageous, for example, when searching for food. PMID:25871143

  7. Collective dynamics of soft active particles

    NASA Astrophysics Data System (ADS)

    van Drongelen, Ruben; Pal, Anshuman; Goodrich, Carl P.; Idema, Timon

    2015-03-01

    We present a model of soft active particles that leads to a rich array of collective behavior found also in dense biological swarms of bacteria and other unicellular organisms. Our model uses only local interactions, such as Vicsek-type nearest-neighbor alignment, short-range repulsion, and a local boundary term. Changing the relative strength of these interactions leads to migrating swarms, rotating swarms, and jammed swarms, as well as swarms that exhibit run-and-tumble motion, alternating between migration and either rotating or jammed states. Interestingly, although a migrating swarm moves slower than an individual particle, the diffusion constant can be up to three orders of magnitude larger, suggesting that collective motion can be highly advantageous, for example, when searching for food.

  8. Saturn's Magnetospheric Cusp: Cassini Observations

    NASA Astrophysics Data System (ADS)

    Jasinski, J. M.; Arridge, C. S.; Sergis, N.; Coates, A. J.; Jones, G. H.

    2015-12-01

    The first in-situ analysis of the high-latitude magnetospheric cusp region at Saturn is presented using data from the Cassini spacecraft. The cusp is a funnel-shaped region where shocked solar wind plasma is able to enter the magnetosphere via the process of magnetic reconnection. The analysis is presented in three sections: Firstly, a high-latitude spacecraft trajectory is shown to cross the northern cusp where magnetosheath plasma is observed in-situ. The ion observations are shown to be a result of `bursty' reconnection occurring at the dayside magnetopause. A different interval is also presented where the southern cusp is observed to oscillate with a period the same as Saturn's rotational period. Secondly, the locations of all the cusp crossings are shown. The field-aligned distances (calculated from observed ion energy-pitch angle dispersions) from the reconnection site are presented. The cusp events are also compared to solar wind propagation models to investigate any correlations. Finally, the magnetic field observations of the cusps are analysed focusing on the diamagnetic depressions. The data are subtracted from a magnetic field model, and the calculated magnetic pressure deficits are compared to the particle pressures. A high plasma pressure layer in the magnetosphere adjacent to the cusp is discovered to also depress the magnetic field.

  9. Reconnection in Planetary Magnetospheres

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    2000-01-01

    Current sheets in planetary magnetospheres that lie between regions of "oppositely-directed" magnetic field are either magnetopause-like, separating plasmas with different properties, or tail-like, separating plasmas of rather similar properties. The magnetopause current sheets generally have a nearly limitless supply of magnetized plasma that can reconnect, possibly setting up steady-state reconnection. In contrast, the plasma on either side of a tail current sheet is stratified so that, as reconnection occurs, the plasma properties, in particular the Alfven velocity, change. If the density drops and the magnetic field increases markedly perpendicular to the sheet, explosive reconnection can occur. Even though steady state reconnection can take place at magnetopause current sheets, the process often appears to be periodic as if a certain low average rate was demanded by the conditions but only a rapid rate was available. Reconnection of sheared fields has been postulated to create magnetic ropes in the solar corona, at the Earth's magnetopause, and in the magnetotail. However, this is not the only way to produce magnetic ropes as the Venus ionosphere shows. The geometry of the reconnecting regions and the plasma conditions both can affect the rate of reconnection. Sorting out the various controlling factors can be assisted through the examination of reconnection in planetary settings. In particular we observe similar small-scale tearing in the magnetopause current layers of the Earth, Saturn. Uranus and Neptune and the magnetodisk current sheet at Jupiter. These sites may be seeds for rapid reconnection if the reconnection site reaches a high Alfven velocity region. In the Jupiter magnetosphere this appears to be achieved with resultant substorm activity. Similar seeds may be present in the Earth's magnetotail with the first one to reach explosive growth dominating the dynamics of the tail.

  10. Magnetospheric and Thermospheric Influence on Ionospheric Outflow

    NASA Astrophysics Data System (ADS)

    Garcia-Sage, K.; Moore, T. E.; Mitchell, E. J.; Olson, D. K.

    2013-12-01

    The Fast Auroral SnapshoT (FAST) small explorer has been used extensively to study ionospheric outflow. Past research has used particle and field data to examine the contemporaneous transfer of electromagnetic energy and particle flow downward from the magnetosphere and upward from the ionosphere. Single event studies published by Strangeway et al. [2005] and Brambles et al. [2011, Supporting Online Material] showed that downward electromagnetic energy and particle flow into the ionosphere are correlated with the upward flow of ions out of the ionosphere. It is expected, however, that this correlation will be affected by circumstances that are unique to each specific event, including but not limited to the outflow location (cusp or nightside), preconditioning due to prior geomagnetic activity, and thermospheric neutral densities. Although knowledge of the thermospheric neutral density is usually unavailable, data from the CHAllenging Minisatellite Payload (CHAMP) is able to provide insight into thermospheric populations at altitudes of about 400 km for a few select events. We expand on the previously-mentioned studies by looking at FAST particle and field data for additional events, and we further examine the influence of thermospheric neutral populations, based on CHAMP data.

  11. TOWARD A REALISTIC PULSAR MAGNETOSPHERE

    SciTech Connect

    Kalapotharakos, Constantinos; Kazanas, Demosthenes; Harding, Alice

    2012-04-10

    We present the magnetic and electric field structures and the currents and charge densities of pulsar magnetospheres that do not obey the ideal condition, E {center_dot} B = 0. Since the acceleration of particles and the production of radiation require the presence of an electric field component parallel to the magnetic field, E{sub ||}, the structure of non-ideal pulsar magnetospheres is intimately related to the production of pulsar radiation. Therefore, knowledge of the structure of non-ideal pulsar magnetospheres is important because their comparison (including models for the production of radiation) with observations will delineate the physics and the parameters underlying the pulsar radiation problem. We implement a variety of prescriptions that support non-zero values for E{sub ||} and explore their effects on the structure of the resulting magnetospheres. We produce families of solutions that span the entire range between the vacuum and the (ideal) force-free electrodynamic solutions. We also compute the amount of dissipation as a fraction of the Poynting flux for pulsars of different angles between the rotation and magnetic axes and conclude that this is at most 20%-40% (depending on the non-ideal prescription) in the aligned rotator and 10% in the perpendicular one. We present also the limiting solutions with the property J = {rho}c and discuss their possible implication on the determination of the 'on/off' states of the intermittent pulsars. Finally, we find that solutions with values of J greater than those needed to null E{sub ||} locally produce oscillations, potentially observable in the data.

  12. Penetration of Large Scale Electric Field to Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Chen, S. H.; Fok, M. C. H.; Sibeck, D. G.; Wygant, J. R.; Spence, H. E.; Larsen, B.; Reeves, G. D.; Funsten, H. O.

    2015-12-01

    The direct penetration of large scale global electric field to the inner magnetosphere is a critical element in controlling how the background thermal plasma populates within the radiation belts. These plasma populations provide the source of particles and free energy needed for the generation and growth of various plasma waves that, at critical points of resonances in time and phase space, can scatter or energize radiation belt particles to regulate the flux level of the relativistic electrons in the system. At high geomagnetic activity levels, the distribution of large scale electric fields serves as an important indicator of how prevalence of strong wave-particle interactions extend over local times and radial distances. To understand the complex relationship between the global electric fields and thermal plasmas, particularly due to the ionospheric dynamo and the magnetospheric convection effects, and their relations to the geomagnetic activities, we analyze the electric field and cold plasma measurements from Van Allen Probes over more than two years period and simulate a geomagnetic storm event using Coupled Inner Magnetosphere-Ionosphere Model (CIMI). Our statistical analysis of the measurements from Van Allan Probes and CIMI simulations of the March 17, 2013 storm event indicate that: (1) Global dawn-dusk electric field can penetrate the inner magnetosphere inside the inner belt below L~2. (2) Stronger convections occurred in the dusk and midnight sectors than those in the noon and dawn sectors. (3) Strong convections at multiple locations exist at all activity levels but more complex at higher activity levels. (4) At the high activity levels, strongest convections occur in the midnight sectors at larger distances from the Earth and in the dusk sector at closer distances. (5) Two plasma populations of distinct ion temperature isotropies divided at L-Shell ~2, indicating distinct heating mechanisms between inner and outer radiation belts. (6) CIMI

  13. Global dynamics of Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Krimigis, Stamatios

    The inclusion in the Cassini payload of the Ion and Neutral Camera (INCA) to perform energetic neutral atom (ENA) imaging, plus an instrument that could measure ion charge state (CHEMS) and, in addition, state-of-the-art electron and ion sensors (LEMMS) provided the tools for a plethora of new and unique observations. These include, but are not limited to: (1) explosive large-scale injections appearing beyond 12 RS in the post-midnight sector, propagate inward, are connected to auroral brightening and SKR emissions, and apparently local injections as far in as 6 RS in the pre-midnight through post-midnight sector with a recurrence period around 11h that appear to corotate past noon; (2) periodicities in energetic charged particles in Saturn’ s magnetosphere, including "dual" periodicities, their slow variations, periodic tilting of the plasma sheet, and the possible explanation of these periodicities by a "wavy" magnetodisk model and the existence of the solar wind "driver" periodicity at ~26 days; (3) dominance of water group (W+) and H+ with a healthy dose of H2+ ions in the energetic particle population throughout the middle magnetosphere,plus the minor species O2+ and 28M+ of known and unknown origins, both with Saturn seasonal and/or solar cycle varying relative abundances; (4) sudden increases in energetic ion intensity around Saturn, in the vicinity of the moons Dione and Tethys, each lasting for several weeks, in response to interplanetary events caused by solar eruptions.; (5) a uniform electric field of around 0.11-0.18 mV/m within 4.4-7.0 RS oriented roughly from noon to midnight, that explains the persistent radial offsets of satellite electron microsignatures from their expected positions; (6) determination that the ring current pressure in the outer magnetosphere is dominated by suprathermal ions heavier than protons; (7) detection of magnetic-field-aligned ion and electron beams (offset several moon radii downstream from Enceladus) with sufficient

  14. Stokesian spherical swimmers and active particles

    NASA Astrophysics Data System (ADS)

    Felderhof, B. U.

    2015-04-01

    The net steady state flow pattern of a distorting sphere is studied in the framework of the bilinear theory of swimming at low Reynolds number. It is argued that the starting point of a theory of interacting active particles should be based on such a calculation, since any arbitrarily chosen steady state flow pattern is not necessarily the result of a swimming motion. Furthermore, it is stressed that as a rule the phase of stroke is relevant in hydrodynamic interactions, so that the net flow pattern must be used with caution.

  15. Magnetospheres in the solar system

    SciTech Connect

    Mcnutt, R.L.

    1984-11-01

    Intrinsic and induced magnetospheres of planets, moons, and comets in the solar system are described. Magnetospheric electric fields, the plasmasphere, rotational effects, and corotation and convection dominated intrinsic magnetospheres are considered. Supersonic and subsonic interactions in induced magnetospheres are discussed. (ESA)

  16. Magnetospheric plasma regions and boundaries

    NASA Technical Reports Server (NTRS)

    Heikkila, W. J.

    1975-01-01

    The boundaries of the various regions of the magnetospheric plasma are considered, taking into account the bow shock, the magnetopause, the outer boundary of the plasma sheet, the inner boundary of the plasma sheet, and the trapping boundary for energetic particles. Attention is given to the steady state, or quasi-steady state, to substorm effects in which temporal changes are important, and to primary auroral processes. A description is presented of the high latitude lobes of the magnetotail. The characteristics of magnetic field topology associated with interconnected interplanetary and geomagnetic field lines are illustrated with the aid of a graph.

  17. Boundary layer dynamics in the description of magnetospheric substorms

    NASA Technical Reports Server (NTRS)

    Eastman, T. E.; Rostoker, G.; Frank, L. A.; Huang, C. Y.; Mitchell, D. G.

    1988-01-01

    This paper presents an analysis of eleven magnetospheric substorm events for which good-quality ground-based magnetometer data and ISEE satellite data were both available. It is shown that the magnetotail particle and field observations associated with a substorm expansive phase can be explained through the spatial movement of the boundary layers and central plasma sheet in the magnetotail. The sweeping of these regions past the satellite, even in the absence of temporal variations within the various regions, can lead to a set of plasma flow observations typical of what is observed in the magnetotail during substorm activity.

  18. Magnetospheric Image Unfolding

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The Grant was a three year grant funded under the Space Physics Supporting Research and Technology and Suborbital Program. Our objective was to develop automated techniques needed to unfold or "invert" global images of the magnetospheric ion populations obtained by the new magnetospheric imaging techniques (ENA, EUV) in anticipation of future missions such as the Magnetospheric Imager and, now, IMAGE. Our focus on the present three year grant is to determine the degree to which such images can quantitatively constrain the global electromagnetic properties of the magnetosphere. In a previous three year grant period we successfully automated a forward modeling inversion algorithm, demonstrated that these inversions are robust in the face of realistic instrumental considerations such as counting statistics and backgrounds, applied error analysis techniques to the extracted parameters using variational procedures, implemented very realistic magnetospheric test images to test the inversion algorithms using the Rice University Magnetospheric Specification Model, and began the process of generating parametric models with the flexibility to handle the realistic magnetospheric images (e.g. Roelof et al, 1992; 1993). Our plan for the present 3 year grant period was to complete the development of the inversion tools needed to handle realistic magnetospheric images, assess the degree to which global electrodynamics is quantitatively constrained by ENA images of the magnetosphere, and bring the inversion of EUV images up to the maturity that we will have achieved for the ENA imaging. Below the accomplishments of our three year effort are present followed by a list of our presentations and publications. The accomplishments of all three years are presented here, and thus some of these items appeared on interim progress reports.

  19. Magnetospheric Periodicities at Saturn Equinox

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.; Mitchell, D. G.; Roelof, E.; Paranicas, C.; Krimigis, S. M.; Krupp, N.; Hamilton, D. C.; Dougherty, M. K.

    2010-12-01

    For several years before equinox, the energetic charged and neutral particles in Saturn’s magnetosphere displayed strong periodicities near 10.8 hours, the same period observed in radio emissions and magnetic fields. These particle periodicities have now been observed at equinox in electrons, protons, oxygen ions, and neutral hydrogen and oxygen atoms at all energies greater than ~3 keV, the lowest energies measured by the Magnetospheric IMaging Instrument (MIMI) on the Cassini spacecraft. The equinoctial electrons exhibit a very strong period at 10.72 hours, while the protons have essentially no periodicity at all. Water group ions display a notable period at 10.73 hours. Both the electrons and the ions have curious overtones in their spectral structure that may be related to solar wind modulation. The energetic neutral hydrogen and oxygen atoms have strong periods of 10.79 hours at equinox. Within the uncertainties of the measurements, the ENA periods are slightly longer than the charged particle periods, although they cover a somewhat different time interval. For comparison, the Cassini magnetometer observed periodicities in Saturn’s magnetic field of 10.65 hours during the same equinoctial interval. These observations will be interpreted in terms of a wavy magnetodisk model.

  20. Nonlinear, relativistic Langmuir waves in astrophysical magnetospheres

    NASA Technical Reports Server (NTRS)

    Chian, Abraham C.-L.

    1987-01-01

    Large amplitude, electrostatic plasma waves are relevant to physical processes occurring in the astrophysical magnetospheres wherein charged particles are accelerated to relativistic energies by strong waves emitted by pulsars, quasars, or radio galaxies. The nonlinear, relativistic theory of traveling Langmuir waves in a cold plasma is reviewed. The cases of streaming electron plasma, electronic plasma, and two-streams are discussed.

  1. Ideal bulk pressure of active Brownian particles

    NASA Astrophysics Data System (ADS)

    Speck, Thomas; Jack, Robert L.

    2016-06-01

    The extent to which active matter might be described by effective equilibrium concepts like temperature and pressure is currently being discussed intensely. Here, we study the simplest model, an ideal gas of noninteracting active Brownian particles. While the mechanical pressure exerted onto confining walls has been linked to correlations between particles' positions and their orientations, we show that these correlations are entirely controlled by boundary effects. We also consider a definition of local pressure, which describes interparticle forces in terms of momentum exchange between different regions of the system. We present three pieces of analytical evidence which indicate that such a local pressure exists, and we show that its bulk value differs from the mechanical pressure exerted on the walls of the system. We attribute this difference to the fact that the local pressure in the bulk does not depend on boundary effects, contrary to the mechanical pressure. We carefully examine these boundary effects using a channel geometry, and we show a virial formula for the pressure correctly predicts the mechanical pressure even in finite channels. However, this result no longer holds in more complex geometries, as exemplified for a channel that includes circular obstacles.

  2. Ideal bulk pressure of active Brownian particles.

    PubMed

    Speck, Thomas; Jack, Robert L

    2016-06-01

    The extent to which active matter might be described by effective equilibrium concepts like temperature and pressure is currently being discussed intensely. Here, we study the simplest model, an ideal gas of noninteracting active Brownian particles. While the mechanical pressure exerted onto confining walls has been linked to correlations between particles' positions and their orientations, we show that these correlations are entirely controlled by boundary effects. We also consider a definition of local pressure, which describes interparticle forces in terms of momentum exchange between different regions of the system. We present three pieces of analytical evidence which indicate that such a local pressure exists, and we show that its bulk value differs from the mechanical pressure exerted on the walls of the system. We attribute this difference to the fact that the local pressure in the bulk does not depend on boundary effects, contrary to the mechanical pressure. We carefully examine these boundary effects using a channel geometry, and we show a virial formula for the pressure correctly predicts the mechanical pressure even in finite channels. However, this result no longer holds in more complex geometries, as exemplified for a channel that includes circular obstacles. PMID:27415318

  3. Space physics: A fast lane in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Hudson, Mary K.

    2013-12-01

    A marriage between satellite observations and modelling has shown that acceleration of electrons in the magnetosphere can be explained by scattering of these particles by plasma oscillations known as chorus waves. See Letter p.411

  4. Magnetospheres of Jupiter, Saturn, and Uranus

    SciTech Connect

    Connerney, J.E.P.

    1987-04-01

    The results published by U.S. scientists during 1983-1986 from studies related to the magnetospheres of Jupiter, Saturn, and Uranus are discussed. Consideration is given to the magnetic fields of these planets, charged particle environments, the interactions between the planetary rings and planetary satellites, the solar wind interactions, radio emissions, and auroras. Special attention is given to observations of (1) a small flux of energetic electrons and protons in the otherwise radiation-free environment in the magnetosphere under the rings of Saturn (interpreted as interactions of Galactic cosmic rays with the rings), (2) spokes, and (3) Saturn ring erosion.

  5. LANL Studies Earth's Magnetosphere

    ScienceCinema

    Daughton, Bill

    2014-08-12

    A new 3-D supercomputer model presents a new theory of how magnetic reconnection works in high-temperature plasmas. This Los Alamos National Laboratory research supports an upcoming NASA mission to study Earth's magnetosphere in greater detail than ever.

  6. Solar and magnetospheric science

    NASA Technical Reports Server (NTRS)

    Timothy, A. F.; Schmerling, E. R.; Chapman, R. D.

    1976-01-01

    The current status of the Solar Physics Program and the Magnetospheric Physics Program is discussed. The scientific context for each of the programs is presented, then the current programs and future plans are outlined.

  7. Magnetospheric and auroral processes

    NASA Technical Reports Server (NTRS)

    Reiff, Patricia H.

    1990-01-01

    Progress was made on the following two projects within the semiannual period: (1) simulations of the magnetic storm of April 1988 using the Magnetospheric Specification Model; and (2) improvement of a user-oriented electric-field model.

  8. LANL Studies Earth's Magnetosphere

    SciTech Connect

    Daughton, Bill

    2011-04-15

    A new 3-D supercomputer model presents a new theory of how magnetic reconnection works in high-temperature plasmas. This Los Alamos National Laboratory research supports an upcoming NASA mission to study Earth's magnetosphere in greater detail than ever.

  9. Space weather: Why are magnetospheric physicists interested in solar explosive phenomena

    NASA Astrophysics Data System (ADS)

    Koskinen, H. E. J.; Pulkkinen, T. I.

    That solar activity drives magnetospheric dynamics has for a long time been the basis of solar-terrestrial physics. Numerous statistical studies correlating sunspots, 10.7 cm radiation, solar flares, etc., with various magnetospheric and geomagnetic parameters have been performed. However, in studies of magnetospheric dynamics the role of the Sun has often remained in the background and only the actual solar wind impinging the magnetosphere has gained most of the attention. During the last few years a new applied field of solar-terrestrial physics, space weather, has emerged. The term refers to variable particle and field conditions in our space environment, which may be hazardous to space-borne or ground-based technological systems and can endanger human life and health. When the modern society is becoming increasingly dependent on space technology, the need for better modelling and also forecasting of space weather becomes urgent. While for post analysis of magnetospheric phenomena it is quite sufficient to include observations from the magnetospheric boundaries out to L1 where SOHO is located, these observations do not provide enough lead-time to run space weather forecasting models and to distribute the forecasts to potential customers. For such purposes we need improved physical understanding and models to predict which active processes on the Sun will impact the magnetosphere and what their expected consequences are. An important change of view on the role of the Sun as the origin of magnetospheric disturbances has taken place during last 10--20 years. For a long time, the solar flares were thought to be the most geoeffective solar phenomena. Now the attention has shifted much more towards coronal mass ejections and the SOHO coronal observations seem to have turned the epoch irreversibly. However, we are not yet ready to make reliable perdictions of the terrestrial environment based on CME observations. From the space weather viewpoint, the key questions are

  10. A New Standard Pulsar Magnetosphere

    NASA Technical Reports Server (NTRS)

    Contopoulos, Ioannis; Kalapotharakos, Constantinos; Kazanas, Demosthenes

    2014-01-01

    In view of recent efforts to probe the physical conditions in the pulsar current sheet, we revisit the standard solution that describes the main elements of the ideal force-free pulsar magnetosphere. The simple physical requirement that the electric current contained in the current layer consists of the local electric charge moving outward at close to the speed of light yields a new solution for the pulsar magnetosphere everywhere that is ideal force-free except in the current layer. The main elements of the new solution are as follows: (1) the pulsar spindown rate of the aligned rotator is 23% larger than that of the orthogonal vacuum rotator; (2) only 60% of the magnetic flux that crosses the light cylinder opens up to infinity; (3) the electric current closes along the other 40%, which gradually converges to the equator; (4) this transfers 40% of the total pulsar spindown energy flux in the equatorial current sheet, which is then dissipated in the acceleration of particles and in high-energy electromagnetic radiation; and (5) there is no separatrix current layer. Our solution is a minimum free-parameter solution in that the equatorial current layer is electrostatically supported against collapse and thus does not require a thermal particle population. In this respect, it is one more step toward the development of a new standard solution. We discuss the implications for intermittent pulsars and long-duration gamma-ray bursts. We conclude that the physical conditions in the equatorial current layer determine the global structure of the pulsar magnetosphere.

  11. A new standard pulsar magnetosphere

    SciTech Connect

    Contopoulos, Ioannis; Kalapotharakos, Constantinos; Kazanas, Demosthenes

    2014-01-20

    In view of recent efforts to probe the physical conditions in the pulsar current sheet, we revisit the standard solution that describes the main elements of the ideal force-free pulsar magnetosphere. The simple physical requirement that the electric current contained in the current layer consists of the local electric charge moving outward at close to the speed of light yields a new solution for the pulsar magnetosphere everywhere that is ideal force-free except in the current layer. The main elements of the new solution are as follows: (1) the pulsar spindown rate of the aligned rotator is 23% larger than that of the orthogonal vacuum rotator; (2) only 60% of the magnetic flux that crosses the light cylinder opens up to infinity; (3) the electric current closes along the other 40%, which gradually converges to the equator; (4) this transfers 40% of the total pulsar spindown energy flux in the equatorial current sheet, which is then dissipated in the acceleration of particles and in high-energy electromagnetic radiation; and (5) there is no separatrix current layer. Our solution is a minimum free-parameter solution in that the equatorial current layer is electrostatically supported against collapse and thus does not require a thermal particle population. In this respect, it is one more step toward the development of a new standard solution. We discuss the implications for intermittent pulsars and long-duration gamma-ray bursts. We conclude that the physical conditions in the equatorial current layer determine the global structure of the pulsar magnetosphere.

  12. The Pulsating Pulsar Magnetosphere

    NASA Astrophysics Data System (ADS)

    Tsui, K. H.

    2015-06-01

    Following the basic principles of a charge-separated pulsar magnetosphere, we consider the magnetosphere to be stationary in space, instead of corotating, and the electric field to be uploaded from the potential distribution on the pulsar surface, set up by the unipolar induction. Consequently, the plasma of the magnetosphere undergoes guiding center drifts of the gyromotion due to the forces transverse to the magnetic field. These forces are the electric force, magnetic gradient force, and field line curvature force. Since these plasma velocities are of drift nature, there is no need to introduce an emf along the field lines, which would contradict the {{E}\\parallel }={\\boldsymbol{E}} \\cdot {\\boldsymbol{B}} =0 plasma condition. Furthermore, there is also no need to introduce the critical field line separating the electron and ion open field lines. We present a self-consistent description where the magnetosphere is described in terms of electric and magnetic fields and also in terms of plasma velocities. The fields and velocities are then connected through the space-charge densities self-consistently. We solve the pulsar equation analytically for the fields and construct the standard steady-state pulsar magnetosphere. By considering the unipolar induction inside the pulsar and the magnetosphere outside the pulsar as one coupled system, and under the condition that the unipolar pumping rate exceeds the Poynting flux in the open field lines, plasma pressure can build up in the magnetosphere, in particular, in the closed region. This could cause a periodic opening up of the closed region, leading to a pulsating magnetosphere, which could be an alternative to pulsar beacons. The closed region can also be opened periodically by the build up of toroidal magnetic field through a positive feedback cycle.

  13. Analysis and visualization of global magnetospheric processes

    SciTech Connect

    Winske, D.; Mozer, F.S.; Roth, I.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The purpose of this project is to develop new computational and visualization tools to analyze particle dynamics in the Earth`s magnetosphere. These tools allow the construction of a global picture of particle fluxes, which requires only a small number of in situ spacecraft measurements as input parameters. The methods developed in this project have led to a better understanding of particle dynamics in the Earth`s magnetotail in the presence of turbulent wave fields. They have also been used to demonstrate how large electromagnetic pulses in the solar wind can interact with the magnetosphere to increase the population of energetic particles and even form new radiation belts.

  14. Global and Seasonal Assessments of Magnetosphere / Ionosphere Coupling via Lightning-Induced Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Sousa, Austin; Marshall, Robert; Close, Sigrid

    2016-07-01

    Pitch-angle scattering by radio waves in the VLF (~3-30kHz) band is thought to be a major loss mechanism for energetic radiation-belt electrons. Resonant interactions with Whistler-mode VLF waves can alter the reflection altitude of trapped electrons ~100keV - 1MeV; when a particle reflects at a low enough altitude, it can be removed from the magnetosphere through collisions with ionospheric constituents. Terrestrial lightning provides a natural and constantly-occurring source of VLF waves. Here we present a global assessment of lightning-induced electron precipitation (LEP) due to resonant pitch-angle scattering from whistler-mode waves, which represent a coupling process between the magnetosphere and ionosphere. We combine an end-to-end model of the LEP process with terrestrial lightning activity data from the GLD360 sensor network to construct a realtime geospatial model of LEP-driven energy deposition into the ionosphere. We explore global and seasonal statistics, provide precipitation estimates across a variety of magnetospheric conditions, and compare the total impact to other magnetospheric loss processes. Additionally, we use our model to optimize event selection from the energetic-particle detectors on board the FIREBIRD CubeSats, in order to download data over the satellite's low-bandwidth downlink. Ultimately, FIREBIRD data will be used to validate our model, and to provide one-to-one correlative measurements of lightning strokes and subsequent precipitation.

  15. Black Hole Magnetospheres

    NASA Astrophysics Data System (ADS)

    Punsly, Brian

    This chapter compares and contrasts winds and jets driven by the two distinct components of the black magnetosphere: the event horizon magnetosphere (the large scale magnetic field lines that thread the event horizon) and the ergospheric disk magnetosphere associated with poloidal magnetic flux threading plasma near the equatorial plane of the ergosphere. The power of jets from the two components as predicted from single-fluid, perfect MHD numerical simulations are compared. The decomposition of the magnetosphere into these two components depends on the distribution of large scale poloidal magnetic flux in the ergosphere. However, the final distribution of magnetic flux in a black hole magnetosphere depends on physics beyond these simple single-fluid treatments, non-ideal MHD (eg, the dynamics of magnetic field reconnection and radiation effects) and two-fluid effects (eg, ion coupled waves and instabilities in the inner accretion flow). In this chapter, it is emphasized that magnetic field line reconnection is the most important of these physical elements. Unfortunately, in single-fluid perfect MHD simulations, reconnection is a mathematical artifact of numerical diffusion and is not determined by physical processes. Consequently, considerable calculational progress is required before we can reliably assess the role of each of these components of black hole magnetospheres in astrophysical systems.

  16. Substorms and magnetospheric energy transfer processes

    NASA Technical Reports Server (NTRS)

    Swift, D. W.

    1980-01-01

    Evidence is presented which suggests a direct process for the conversion of solar wind energy into the various manifestations of the auroral substorm. This is in contrast to the widely accepted premise that solar wind energy is accumulated in the magnetosphere and then released by an instability process occurring in the magnetotail. It is shown that much of the plasma sheet behavior associated with auroral substorms can be interpreted in terms of single-particle models and simple variations of the cross-tail electric field intensity which does not invoke release of stored magnetic energy. It is also pointed out that the major entry of substorm energy into the magnetosphere occurs through the boundaries of the lobes of the magnetotail. This paper is not intended to be a complete theory of the magnetospheric substorm - rather the intention of this paper is to point out directions of research deserving of more attention.

  17. Characteristics of magnetospheric radio noise spectra

    NASA Technical Reports Server (NTRS)

    Herman, J. R.

    1976-01-01

    Magnetospheric radio noise spectra (30 kHz to 10 MHz) taken by IMP-6 and RAE-2 exhibit time-varying characteristics which are related to spacecraft position and magnetospheric processes. In the mid-frequency range (100-1,000 kHz) intense noise peaks rise by a factor of 100 or more above background; 80% of the peak frequencies are within the band 125 kHz to 600 kHz, and the peak occurs most often (18% of the time) at 280 kHz. This intense mid-frequency noise has been detected at radial distances from 1.3 Re to 60 Re on all sides of the Earth during magnetically quiet as well as disturbed periods. Maximum occurrence of the mid-frequency noise is in the evening to midnight hours where splash-type energetic particle precipitation takes place. ""Magnetospheric lightning'' can be invoked to explain the spectral shape of the observed spectra.

  18. Mixing in suspensions of active particles

    NASA Astrophysics Data System (ADS)

    Pushkin, Dmitri O.; Yeomans, Julia M.

    2014-03-01

    Microscopic active particles self-propelling in the surrounding fluid create flows that eventually lead to emergence of non-equilibrium states with long-ranged fluctuations. One of the technologically important consequences of these fluctuations is enhanced mixing of the surrounding fluid. It is also critical for understanding the ecology of a particular type of biological active systems, bacterial suspension, as the enhanced mixing strongly alters the fluxes of nutrients. We consider the theoretical foundations of fluid mixing enhancement in dilute suspensions of active force-free swimmers. We describe the impediments to fluid mixing imposed by the physical nature of fluid flows created by swimmers, and different ways of overcoming them. We show that fluid mixing in 3D suspensions of force-free (dipolar) swimmers is dominated by the effect of curvature of their trajectories, and obtain an exact analytical expression for the corresponding effective diffusion coefficient. Our results highlight limitations of alternative ``effective temperature'' approaches and may serve as a quantitative tool for designing technological applications.

  19. Energetics of the magnetosphere, revised

    NASA Technical Reports Server (NTRS)

    Stern, D. P.

    1984-01-01

    The approximate magnitudes of power inputs and energies associated with the Earth's magnetosphere were derived. The nearest 40 R sub E of the plasma sheet current receive some 3.10 to the 11th power watt, and much of this goes to the Birkeland currents, which require 1-3 10 to the 11th power watt. Of that energy, about 30% appears as the energy of auroral particles and most of the rest as ionosphere joule heating. The ring current contains about 10 to the 15th power joule at quiet times, several times as much during magnetic storms, and the magnetic energy stored in the tail lobes is comparable. Substorm energy releases may range at 1.5 to 30 10 to the 11th power watt. Compared to these, the local energy release rate by magnetic merging in the magnetosphere is small. Merging is essential for the existence of open field lines, which make such inputs possible. Merging also seems to be implicated in substorms: most of the released energy only becomes evident far from the merging region, though some particles may gain appreciable energy in that region itself, if the plasma sheet is squeezed out completely and the high latitude lobes interact directly.

  20. Inner Magnetosphere Simulations: Exploring Magnetosonic Wave Generation Conditions

    NASA Astrophysics Data System (ADS)

    Zaharia, S. G.; Jordanova, V. K.; MacDonald, E.; Thomsen, M. F.

    2012-12-01

    We investigate the conditions for magnetosonic wave generation in the near-Earth magnetosphere by performing numerical simulations with our newly improved self-consistent model, RAM-SCB. The magnetosonic (ion Bernstein) instability, a potential electron acceleration mechanism in the outer radiation belt, is driven by a positive slope in the ion distribution function perpendicular to the magnetic field, a so-called "velocity ring" distribution at energies above 1 keV. The formation of such distributions is dependent on the interplay of magnetic and electric drifts, as well as ring current losses, and therefore its study requires a realistic treatment of both plasma and field dynamics. The RAM-SCB model represents a 2-way coupling of the kinetic ring current-atmosphere interactions model (RAM) with a 3D plasma equilibrium code. In RAM-SCB the magnetic field is computed in force balance with the RAM anisotropic pressures and then returned to RAM to guide the particle dynamics. RAM-SCB thus properly treats both the kinetic drift physics crucial in the inner magnetosphere and the self-consistent interaction between plasma and magnetic field (required due to the strong field depressions during storms, depressions that strongly affect particle drifts). In order to provide output at geosynchronous locations, recently the RAM-SCB boundary has been expanded to 9 RE from Earth, with plasma pressure and magnetic field boundary conditions prescribed there from empirical models. This presentation will analyze, using event simulations with the improved model and comparisons with LANL MPA geosynchronous observations, the occurrence and location of magnetosonic unstable regions in the inner magnetosphere and their dependence on the following factors: 1). geomagnetic activity level (including quiet time, storm main phase and recovery); 2). magnetic field self-consistency (stretched vs. dipole fields). We will also discuss the physical mechanism for the occurrence of the velocity

  1. Modeling of Inner Magnetosphere Coupling Processes

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.

    2011-01-01

    The Ring Current (RC) is the biggest energy player in the inner magnetosphere. It is the source of free energy for Electromagnetic Ion Cyclotron (EMIC) wave excitation provided by a temperature anisotropy of RC ions, which develops naturally during inward E B convection from the plasmasheet. The cold plasmasphere, which is under the strong influence of the magnetospheric electric field, strongly mediates the RC-EMIC wave-particle-coupling process and ultimately becomes part of the particle and energy interplay. On the other hand, there is a strong influence of the RC on the inner magnetospheric electric and magnetic field configurations and these configurations, in turn, are important to RC dynamics. Therefore, one of the biggest needs for inner magnetospheric research is the continued progression toward a coupled, interconnected system with the inclusion of nonlinear feedback mechanisms between the plasma populations, the electric and magnetic fields, and plasma waves. As we clearly demonstrated in our studies, EMIC waves strongly interact with electrons and ions of energies ranging from approx.1 eV to approx.10 MeV, and that these waves strongly affect the dynamics of resonant RC ions, thermal electrons and ions, and the outer RB relativistic electrons. As we found, the rate of ion and electron scattering/heating in the Earth's magnetosphere is not only controlled by the wave intensity-spatial-temporal distribution but also strongly depends on the spectral distribution of the wave power. The latter is also a function of the plasmaspheric heavy ion content, and the plasma density and temperature distributions along the magnetic field lines. The above discussion places RC-EMIC wave coupling dynamics in context with inner magnetospheric coupling processes and, ultimately, relates RC studies with plasmaspheric and Superthermal Electrons formation processes as well as with outer RB physics.

  2. The Physics of the Laboratory Magnetosphere

    NASA Astrophysics Data System (ADS)

    Mauel, Michael

    2015-11-01

    During the past decade, experiments and simulations have characterized a new regime of high-beta toroidal plasma confinement using unique facilities, called laboratory magnetospheres. In a laboratory magnetosphere, a large plasma is confined by a relatively small, magnetically levitated, superconducting current ring. Nonlinear processes, including the inverse cascade of turbulent fluctuations and turbulent self-organization, are studied and controlled in near steady-state conditions. Because a dipole's magnetic field lines resemble the inner regions of planetary magnetospheres, these studies link laboratory and space plasma physics. However, unlike planetary magnetospheres, the magnetic field lines from a levitated dipole are axisymmetric and closed, imparting unique properties to the laboratory magnetosphere. A levitated dipole confines plasma without field-aligned currents, even when plasma pressure exceeds the local magnetic pressure (β > 1). Particle drifts are omnigeneous, and the dynamics of passing and trapped particles are similar. Because parallel currents can be a source for instability, many well-known low-frequency instabilities found in other toroidal configurations, like kink, tearing, ballooning, and drift modes, are not found in a dipole plasma torus. Instead, interchange and entropy modes, which resonate with bounce-averaged magnetic drifts, dominate plasma dynamics. This review emphasizes observations from the levitated dipole experiments at MIT and at the University of Tokyo, shows the application of gyrokinetic simulations and bounce-averaged fluid models with drift-kinetic closures to model the physics of the up-gradient turbulent pinch, describes the structure and chaotic dynamics of interchange and entropy mode instability, and introduces opportunities to apply the new physics of the laboratory magnetosphere to explore turbulent transport processes within a large quasi-steady magnetized plasma torus. Acknowledging contributions from Drs. D

  3. Effects of Io's volcanos on the plasma torus and Jupiter's magnetosphere

    SciTech Connect

    Cheng, A.F.

    1980-12-01

    Io's volcanism can have dominant effects on Jupiter's magnetosphere. A model is developed in which a neutral gas torus is formed at Io's orbit by volcanic SO/sub 2/ escaping from Io. Ionization and dissociation of volcanic SO/sub 2/ is shown to be the dominant source of plasma in Jupiter's magnetosphere. The failure of Voyager observations to confirm predictions of the magnetic anomaly model is naturally explained. A 30--50 KeV sulfur and oxygen ion plasma is formed in the outer magnetosphere, with density roughly equal to the proton density there, by ionization of sulfur and oxygen atoms on highly eccentric elliptical orbits around Jupiter. When these atoms are ionized in the outer magnetosphere, they are swept up by the Jovian magnetic field and achieve 30--50 keV energies. Such atoms are created by dissociative attachment of SO/sub 2/ by < or approx. =10 eV electrons. Substantial losses of radiation-belt charged particles result from passage through the neutral gas torus. Such losses can account for observed anomalies in charged particle depletions near Io; these could not be understood in terms of satellite sweeping alone. Substantial ionization energy loss occurs for < or approx. =1 MeV protons and < or approx. =100 keV electrons; losses of < or approx. =1 MeV protons are much greater than for comparable energy electrons. Losses of < or approx. =1 MeV per nucleon ions are also severe. Other consequences of the model include intrinsic time variability in the Jovian magnetosphere, on times > or approx. =10/sup 6/ s, caused by variations in Io's volcanic activity. Charged particle losses in the neutral gas torus tend to yield dumbbell-shaped pitch-angle distributions. Negative ions are predicted in the Io plasma torus.

  4. On the acceleration of energetic ions in Jupiter's magnetosphere

    NASA Astrophysics Data System (ADS)

    Barbosa, D. D.; Eviatar, A.; Siscoe, G. L.

    1984-06-01

    Several aspects of the problem of high-energy ions in the Jovian magnetosphere are addressed. Voyager observations pertaining to the problem of high-energy ions in the magnetosphere are summarized, and the charge exchange emission of fast neutral sulfur and oxygen atoms and their subsequent recapture by electron impact, charge exchange, and photoionization is considered. Solutions are given to the diffusion equation assuming a source of ions injected with a gyroenergy corresponding to pickup in the middle and outer magnetosphere. It is concluded that no reasonable model parameters exist to produce the required steep spectra of the particle observations with only pickup and adiabatic radial diffusion included. A local acceleration mechanism based on nonadiabatic wave-particle interactions is needed. The assumptions and model predictions of stochastic acceleration by MHD turbulence for the Jovian magnetosphere are described. The model makes a specific correspondence between MHD wave spectrum properties and particle spectrum properties at energies above the Alfven energy.

  5. Optically active biological particle distinguishing apparatus

    DOEpatents

    Salzman, Gary C.; Kupperman, Robert H.

    1989-01-01

    The disclosure is directed to organic particle sorting and identification. High frequency pulses of circularly polarized light, alternating between left and right, intersect a fast moving stream of organic particles. Circular intensity differential scattering and linear intensity differential scattering are monitored to uniquely identify a variety of organic particles.

  6. Ulf waves in the low-latitude boundary layer and their relationship to magnetospheric pulsations: A multisatellite observation

    SciTech Connect

    Takahashi, K.; Sibeck, D.G.; Newell, P.T.; Spence, H.E.

    1994-01-31

    On April 30 (day 120), 1985, the magnetosphere was compressed at 0923 UT and the subsolar magnetopause remained near 7 RE geocentric for approx. 2 hours, during which the four spacecraft Spacecraft Charging At High Altitude (SCATHA), GOES 5, GOES 6, and Active Magnetospheric Particle Tracer Explorers (AMPTE) CCE were all in the magnetosphere on the morning side. SCATHA was in the low-latitude boundary layer (LLBL) in the second half of this period. The interplanetary magnetic field was inferred to be northward from the characteristics of precipitating particle fluxes as observed by the low-altitude satellite Defense Meteorological Satellite Program (DMSP) F7 and also from absence of substorms. The authors used magnetic field and particle data from this unique interval to study ULF waves in the LLBL and their relationship to magnetic pulsations in the magnetosphere. The LLBL was identified from the properties of particles, including bidirectional field-aligned electron beams at approx. 200 eV. In the boundary layer the magnetic field exhibited both a 5-10 min irregular compressional oscillation and a broadband (Delta(f)/f approx. 1) primarily transverse oscillations with a mean period of approx. 50 s and a left-hand sense of polarization about the mean field. The former can be observed by other satellites and is likely due to pressure variations in the solar wind, while the latter is likely due to a Kelvin-Helmoltz (K.-H.) instability occurring in the LLBL or on the magnetopause.

  7. Planet/magnetosphere/satellite couplings: Observations from the moon

    NASA Astrophysics Data System (ADS)

    Prange, Renee

    1994-06-01

    The general characteristics of planetary magnetospheres depend upon a few key parameters, such as the magnetic dipole strength, the planetary rotation rate, and the strength of the internal plasma sources (satellites, rings, ionosphere). The present knowledge of the acceleration and of the large scale circulation of plasma in these magnetospheres is still rather poor. Plasma and energetic particle losses occur largely through precipitation into the atmosphere along magnetic field lines, giving rise to the planetary aurorae. These losses can be initiated by various kinds of magnetospheric processes, and, if clearly understood, could give major insights into the physics of the global magnetospheric system. After a brief comparative review of the planetary magnetospheres, it will be shown how our understanding of their dynamics could benefit from increased instrumental performances in terms of remote sensing in the X rays, UV to IR, and radio wavelength range, and what breakthroughs could be expected from lunar based observations.

  8. Evidence for global electron transportation into the jovian inner magnetosphere.

    PubMed

    Yoshioka, K; Murakami, G; Yamazaki, A; Tsuchiya, F; Kimura, T; Kagitani, M; Sakanoi, T; Uemizu, K; Kasaba, Y; Yoshikawa, I; Fujimoto, M

    2014-09-26

    Jupiter's magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves. PMID:25258073

  9. Dione's Magnetospheric Interaction

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Hospodarsky, G. B.; Schippers, P.; Moncuquet, M.; Lecacheux, A.; Crary, F. J.; Khurana, K. K.; Mitchell, D. G.

    2015-12-01

    Cassini has executed four close flybys of Dione during its mission at Saturn with one additional flyby planned as of this writing. The Radio and Plasma Wave Science (RPWS) instrument observed the plasma wave spectrum during each of the four encounters and plans to make additional observations during the 17 August 2015 flyby. These observations are joined by those from the Cassini Plasma Spectrometer (CAPS), Magnetospheric Imaging Instrument (MIMI), and the Magnetometer instrument (MAG), although neither CAPS nor MAG data were available for the fourth flyby. The first and fourth flybys were near polar passes while the second and third were near wake passes. The second flyby occurred during a time of hot plasma injections which are not thought to be specifically related to Dione. The Dione plasma wave environment is characterized by an intensification of the upper hybrid band and whistler mode chorus. The upper hybrid band shows frequency fluctuations with a period of order 1 minute that suggest density variations of up to 10%. These density variations are anti-correlated with the magnetic field magnitude, suggesting a mirror mode wave. Other than these periodic density fluctuations there appears to be no local plasma source which would be observed as a local enhancement in the density although variations in the electron distribution are apparent. Wake passages show a deep density depletion consistent with a plasma cavity downstream of the moon. Energetic particles show portions of the distribution apparently absorbed by the moon leading to anisotropies that likely drive both the intensification of the upper hybrid band as well as the whistler mode emissions. We investigate the role of electron anisotropies and enhanced hot electron fluxes in the intensification of the upper hybrid band and whistler mode emissions.

  10. Revision of the DELFIC Particle Activity Module

    SciTech Connect

    Hooper, David A; Jodoin, Vincent J

    2010-09-01

    The Defense Land Fallout Interpretive Code (DELFIC) was originally released in 1968 as a tool for modeling fallout patterns and for predicting exposure rates. Despite the continual advancement of knowledge of fission yields, decay behavior of fission products, and biological dosimetry, the decay data and logic of DELFIC have remained mostly unchanged since inception. Additionally, previous code revisions caused a loss of conservation of radioactive nuclides. In this report, a new revision of the decay database and the Particle Activity Module is introduced and explained. The database upgrades discussed are replacement of the fission yields with ENDF/B-VII data as formatted in the Oak Ridge Isotope Generation (ORIGEN) code, revised decay constants, revised exposure rate multipliers, revised decay modes and branching ratios, and revised boiling point data. Included decay logic upgrades represent a correction of a flaw in the treatment of the fission yields, extension of the logic to include more complex decay modes, conservation of nuclides (including stable nuclides) at all times, and conversion of key variables to double precision for nuclide conservation. Finally, recommended future work is discussed with an emphasis on completion of the overall radiation physics upgrade, particularly for dosimetry, induced activity, decay of the actinides, and fractionation.

  11. Dynamics of two interacting active Janus particles

    NASA Astrophysics Data System (ADS)

    Bayati, Parvin; Najafi, Ali

    2016-04-01

    Starting from a microscopic model for a spherically symmetric active Janus particle, we study the interactions between two such active motors. The ambient fluid mediates a long range hydrodynamic interaction between two motors. This interaction has both direct and indirect hydrodynamic contributions. The direct contribution is due to the propagation of fluid flow that originated from a moving motor and affects the motion of the other motor. The indirect contribution emerges from the re-distribution of the ionic concentrations in the presence of both motors. Electric force exerted on the fluid from this ionic solution enhances the flow pattern and subsequently changes the motion of both motors. By formulating a perturbation method for very far separated motors, we derive analytic results for the translation and rotational dynamics of the motors. We show that the overall interaction at the leading order modifies the translational and rotational speeds of motors which scale as O (" separators=" [ 1 / D ] 3 ) and O (" separators=" [ 1 / D ] 4 ) with their separation, respectively. Our findings open up the way for studying the collective dynamics of synthetic micro-motors.

  12. Electrostatic waves in the magnetosphere.

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Fredricks, R. W.

    1972-01-01

    Electric dipole antennas on magnetospheric spacecraft measure E field components of many kinds of electromagnetic waves. In addition, lower hybrid resonance emissions are frequently observed well above the ionosphere. The Ogo 5 plasma wave experiment has also detected new forms of electrostatic emissions that appear to interact very strongly with the local plasma particles. Greatly enhanced wave amplitudes have been found during the expansion phases of substorms, and analysis indicates that these emissions produce strong pitch angle diffusion. Intense broadband electrostatic turbulence is also detected at current layers containing steep magnetic field gradients. This current-driven instability is operative at the bow shock and also at field null regions just within the magnetosheath, and at the magnetopause near the dayside polar cusp. The plasma turbulence appears to involve ion acoustic waves, and the wave particle scattering provides an important collisionless dissipation mechanism for field merging.

  13. The population of the magnetosphere by solar winds ions when the interplanetary magnetic field is northward

    NASA Technical Reports Server (NTRS)

    Richard, Robert L.; Walker, Raymond J.; Ashour-Abdalla, Maha

    1994-01-01

    We have examined some possible entry mechanisms of solar wind ions into the magnetosphere by calculating the trajectories of thousands of non-interacting ions in the magnetic and electric fields from a three dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere and the magnetosheath, under northward interplanetary magnetic field (IMF) conditions. Particles, launched in the solar wind, entered the magnetosphere and formed the low latitude boundary layer (LLBL), plasma sheet and a region of trapped particles near the Earth. The densities and temperatures we obtained in these regions were realistic, with the exception of trapped particle densities. The dominant entry mechanism was convection into the magnetosphere on reconnecting field lines.

  14. Magnetic and plasma response of the Earth's magnetosphere to interplanetary shock

    NASA Astrophysics Data System (ADS)

    Du, A.; Cao, X.; Wang, R.; Zhang, Y.

    2013-12-01

    In this paper, we investigate the global response of magnetosphere to interplanetary shock, and focus on the magnetic and plasma variations related to aurora. The analysis utilizes data from simultaneous observations of interplanetary shocks from available spacecraft in the solar wind and the Earth's magnetosphere such as ACE, Wind and SOHO in solar wind, LANL and GOES in outer magnetosphere, TC1 in the midinight neutral plasma sheet, Geotail and Polar in dusk side of plasma sheet, and Cluster in downside LLBL. The shock front speed is ~1051 km/s in the solar wind, and ~981km/s in the Earth's magnetosphere. The shock is propagating anti-sunward (toward the Earth) in the plasma frame with a speed of ~320 km/s. After the shock bumps at the magnetopause, the dayside aurora brightens, then nightside aurora brightens and expanses to poleward. During the aurora activity period, the fast earthward and tailward flows in plasma sheet are observed by TC1 (X~7.1 Re, Y~1.2 Re). The variation of magnetic field and plasma in duskside of magnetosphere is weaker than that in dawnside. At low latitude boundary layer (LLBL), the Cluster spacecraft detected rolled-up large scale vortices generated by the Kelvin-Helmholtz instability (KHI). Toroidal oscillations of the magnetic field in the LLBL might be driven by the Kelvin-Helmholtz instability. The strong IP shock highly compresses the magnetopause and the outer magnetosphere. This process may also lead to particle precipitation and auroral brightening (Zhou and Tsurutani, 1999; Tsurutani et al., 2001 and 2003).

  15. Using Space Weather Forecast Tools for Understanding Planetary Magnetospheres: MESSENGER Experience Applied to MAVEN Studies

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.; Dewey, R. M.; Brain, D. A.; Jakosky, Bruce; Halekas, Jasper; Connerney, Jack; Odstrcil, Dusan; Mays, M. Leila; Luhmann, Janet

    2015-04-01

    The Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool has been used to calculate the values of interplanetary magnetic field (IMF) strength (B), solar wind speed (V), density (n), ram pressure (~nV2), cross-magnetosphere electric field (VxB), Alfvén Mach number (MA), and other derived quantities of relevance for space weather purposes at Earth. Such parameters as solar wind dynamic pressure can be key for estimating the magnetopause standoff distance, as just one example. The interplanetary electric field drives many magnetospheric dynamical processes and can be compared with general magnetic activity indices and with the occurrence of energetic particle bursts within the Earth’s magnetosphere. Such parameters also serve as input to the global magnetohydrodynamic and kinetic magnetosphere models that are used to forecast magnetospheric and ionospheric processes. Such modeling done for Earth space weather forecasting has helped assess near-real-time magnetospheric behavior for MESSENGER at Mercury (as well as other mission analysis and Mercury ground-based observational campaigns). This solar-wind forcing knowledge has provided a crucial continuing step toward bringing heliospheric science expertise to bear on solar-planetary interaction studies. The experience gained from MESSENGER at Mercury is now being applied to the new observations from the MAVEN (Mars Atmosphere and Volatile Evolution) mission at Mars. We compare the continuous WSA-ENLIL results derived from modeling to the MAVEN SWIA and MAG data from mid-December 2014 to the present time. This provides a broader contextual view of solar wind forcing at Mars and also allows a broader validation of the ENLIL model results throughout the inner heliosphere.

  16. The ionospheric source of magnetospheric plasma is not a black box input for global models

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Liemohn, M. W.

    2016-06-01

    Including ionospheric outflow in global magnetohydrodynamic models of near-Earth outer space has become an important step toward understanding the role of this plasma source in the magnetosphere. Of the existing approaches, however, few tie the outflowing particle fluxes to magnetospheric conditions in a self-consistent manner. Doing so opens the magnetosphere-ionosphere system to nonlinear mass-energy feedback loops, profoundly changing the behavior of the magnetosphere-ionosphere system. Based on these new results, it is time for the community eschew treating ionospheric outflow as a simple black box source of magnetospheric plasma.

  17. Saturn's Magnetospheric Boundaries

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Gurnett, D. A.; Hospodarsky, G. B.; Dougherty, M. K.; Arridge, C. S.; Achilleos, N. A.; Andre, N.; Crary, F. J.; McAndrews, H. J.; Szego, K.; Rymer, A. M.; Krimigis, S. M.; Mitchell, D. G.; Krupp, N.; Hamilton, D. C.; Hansen, K. C.

    2005-12-01

    Cassini has now been in orbit at Saturn for more than a year, making more than 12 passes through Saturn's magnetosphere. While the apoapses of these orbits have so far remained clustered near dawn and the inclinations have been mostly below about 20 degrees, progress has been made in mapping and understanding various magnetospheric boundaries. For example, initial modeling of the bow shock and magnetopause by Hendricks et al. [GRL, 32, 2005] suggest the magnetosphere is somewhat more inflated than thought from Pioneer- and Voyager-based models. Of perhaps even more interest are internal boundaries within the magnetosphere. These boundaries separate various magnetospheric regions and are less rigorously defined than the external boundaries. In fact, a number of authors have identified different regions based on particular sets of measurements; we review some of these and attempt to integrate these into a scheme of general utility, realizing that ongoing work on interpretation of existing observations and high inclination orbits to come will likely modify any such scheme we may devise this early in Cassini's tour.

  18. Geospace Magnetospheric Dynamics Mission

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Kluever, C.; Burch, J. L.; Fennell, J. F.; Hack, K.; Hillard, G. B.; Kurth, W. S.; Lopez, R. E.; Luhmann, J. G.; Martin, J. B.; Hanson, J. E.

    1998-01-01

    The Geospace Magnetospheric Dynamics (GMD) mission is designed to provide very closely spaced, multipoint measurements in the thin current sheets of the magnetosphere to determine the relation between small scale processes and the global dynamics of the magnetosphere. Its trajectory is specifically designed to optimize the time spent in the current layers and to minimize radiation damage to the spacecraft. Observations are concentrated in the region 8 to 40 R(sub E) The mission consists of three phases. After a launch into geostationary transfer orbit the orbits are circularized to probe the region between geostationary orbit and the magnetopause; next the orbit is elongated keeping perigee at the magnetopause while keeping the line of apsides down the tail. Finally, once apogee reaches 40 R(sub E) the inclination is changed so that the orbit will match the profile of the noon-midnight meridian of the magnetosphere. This mission consists of 4 solar electrically propelled vehicles, each with a single NSTAR thruster utilizing 100 kg of Xe to tour the magnetosphere in the course of a 4.4 year mission, the same thrusters that have been successfully tested on the Deep Space-1 mission.

  19. Saturn's magnetosphere, rings, and inner satellites

    NASA Astrophysics Data System (ADS)

    van Allen, J. A.; Thomsen, M. F.; Randall, B. A.; Rairden, R. L.; Grosskreutz, C. L.

    1980-01-01

    The discovery of the Saturn magnetosphere and its characterization by Pioneer 11 are reported, and findings on the planet's rings and satellites obtained by energetic charged particle measurements within the inner magnetosphere are presented. Bow shock crossings identified by the Pioneer plasma analyzer and magnetometer at distances of 24.1, 23.1 and 20.0 Saturn radii indicate the presence of a magnetosphere with physical dimensions and charged particle populations intermediate between those of the earth and Jupiter, with a scale more similar to that of the earth. Particle angular distributions on the inbound leg of the trajectory are consistent with a dipole magnetic field approximately perpendicular to the planet's equator, while on the outbound leg the distributions indicate the presence of an equatorial current sheet. Charged particle absorption features are detected at the orbits of Dione and Mimas, encompassing the orbits of Tethys and Enceladus, and at 2.534 and 2.343 Saturn radii indicating the presence of satellites of diameters greater than 170 km. Charged particle measurements also confirm the Pioneer division in the rings between 2.292 and 2.336 Saturn radii, a suspected satellite at 2.82 Saturn radii, the presence of the F ring between 2.336 and 2.371 Saturn radii and the outer radius of the A ring at 2.292 Saturn radii.

  20. Comprehensive Quantitative Model of Inner-Magnetosphere Dynamics

    NASA Technical Reports Server (NTRS)

    Wolf, Richard A.

    2002-01-01

    This report includes descriptions of papers, a thesis, and works still in progress which cover observations of space weather in the Earth's magnetosphere. The topics discussed include: 1) modelling of magnetosphere activity; 2) magnetic storms; 3) high energy electrons; and 4) plasmas.

  1. Modeling Saturn's Magnetospheric Field

    NASA Astrophysics Data System (ADS)

    Khurana, K. K.; Leinweber, H. K.; Russell, C. T.; Dougherty, M. K.

    2015-12-01

    The Cassini spacecraft has now provided an excellent coverage of radial distances, local times and latitudes in Saturn's magnetosphere. The magnetic field observations from Cassini continue to provide deep insights on the structure and dynamics of Saturn's magnetosphere. Two of the unexpected findings from Saturn's magnetosphere are that the current sheet of Saturn assumes a shallow saucer like shape from the forcing of the solar wind on the magnetosphere and that rotational diurnal periodicities are ubiquitous in a magnetosphere formed by an axisymmetric internal field from Saturn. We have used the comprehensive magnetic field data from Cassini to construct a versatile new model of Saturn's magnetospheric field for use in current and future data analysis. Our model consists of fully shielded modules that specify the internal spherical harmonic field of Saturn, the ring current and the magnetotail current systems and the interconnection magnetic field from the solar wind IMF. The tilt and hinging of the current sheet is introduced by using the general deformation technique [Tsyganenko, 1998]. In the new model, Saturn's current sheet field is based on Tsyganenko and Peredo [1994] formalism for disk-shaped current sheets. The shielding field from the magnetopause for the equatorial current sheet and the internal field is specified by Cartesian and cylindrical harmonics, respectively. To derive the shielding fields we use a model of the magnetopause constructed from magnetopause crossings observed by both Cassini and Voyager (Arridge et al. 2006). The model uses observations from Pioneer, Voyager and Cassini. A comparison of model field with the observations will be presented. Finally, we discuss both the applications of the new model and its further generalization using data from the proximal orbit phase of Cassini.

  2. Magnetospheric convection during quiet or moderately disturbed times

    NASA Technical Reports Server (NTRS)

    Caudal, G.; Blanc, M.

    1988-01-01

    The processes which contribute to the large-scale plasma circulation in the earth's environment during quiet times, or during reasonable stable magnetic conditions are reviewed. The various sources of field-aligned current generation in the solar wind and the magnetosphere are presented. The generation of field-aligned currents on open field lines connected to either polar cap and the generation of closed field lines of the inner magnetosphere are examined. Consideration is given to the hypothesis of Caudal (1987) that loss processes of trapped particles are competing with adiabatic motions in the generation of field-aligned currents in the inner magnetosphere.

  3. Transport of active ellipsoidal particles in ratchet potentials

    SciTech Connect

    Ai, Bao-Quan Wu, Jian-Chun

    2014-03-07

    Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, while for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities)

  4. Frequency dispersion of electrokinetically activated Janus particles

    NASA Astrophysics Data System (ADS)

    Boymelgreen, Alicia; Balli, Tov; Yossifon, Gilad; Miloh, Touvia

    2015-11-01

    We examine the influence of the applied frequency of the electric field on the induced-charge electroosmotic flow around a metallo-dielectric Janus particle. Previously, we have used three dimensional-two component micro-particle-image-velocimetry (3D-2C μ PIV) around a stagnant particle, to illustrate the presence of a number of competing effects including dielectrophoresis and electrohydrodynamic flow which distort both the strength and shape of the frequency dispersion predicted for pure induced-charge effects. Here, we extend this work by examining the frequency dispersion of mobile Janus particles of different sizes (3 - 15 μm in diameter) at different electrolyte concentrations. In all cases, towards the DC limit, and in the frequency domain where previously EHD flow was shown to dominate, the velocity of a mobile particle decays to zero. At the same time significant variations in the frequency dispersion, including its shape and the value for maximum velocity are recorded as a function of both electrolyte concentration and particle size. This work is of both fundamental and practical importance and may be used to further refine non-linear electrokinetic theory and optimize the application of Janus particles as carriers in lab-on-a-chip analysis systems.

  5. Energetic particles at Uranus

    NASA Technical Reports Server (NTRS)

    Cheng, Andrew F.; Krimigis, S. M.; Lanzerotti, L. J.

    1991-01-01

    The energetic particle measurements by the low-energy charged-particle and cosmic-ray instruments on the Voyager 2 spacecraft in the magnetosphere of Uranus are reviewed. Upstream events were observed outside the Uranian bow shock, probably produced by ion escape from the magnetosphere. Evidence of earthlike substorm activity was discovered within the Uranian magnetosphere. A proton injection event was observed within the orbit of Umbriel and proton events were observed in the magnetotail plasma-sheet boundary layer that are diagnostic of earthlike substorms. The magnetospheric composition is totally dominated by protons, with only a trace abundance of H(2+) and no evidence for He or heavy ions; the Uranian atmophere is argued to be the principal plasma source. Phase-space densities of medium energy protons show inward radial diffusion and are quantitatively similar to those observed at the earth, Jupiter, and Saturn. These findings and plasma wave data suggest the existence of structures analogous to the earth's plasmasphere and plasmapause.

  6. Life cycle of a comet magnetosphere

    NASA Astrophysics Data System (ADS)

    Nilsson, Hans; Stenberg Wieser, Gabriella; Behar, Etienne

    2016-04-01

    Rosetta has followed comet 67P from low activity at more than 3 AU heliocentric distance to high activity at perihelion and then out again. We study the evolution of the dynamic ion environment using the RPC-ICA ion spectrometer. Initially the solar wind permeated the near comet environment. The solar wind was deflected due to mass loading, but not much slowed down. In mid to late April 2015 the solar wind started to disappear from the observation region. This was associated with the solar wind deflection reaching 90°, indicating that the solar wind free region formed due to severe mass loading and associated solar wind deflection. A comet magnetosphere had formed. Accelerated water ions, moving mainly in the anti-sunward direction kept being observed also after the solar wind disappeared from the location of Rosetta. We report how the accelerated water ion environment changed as Rosetta was located relatively deeper in the comet magnetosphere as comet activity increased. Shortly after perihelion, Rosetta made an excursion to 1500 km cometocentric distance, the only data providing a spatial context to the observations made inside the comet magnetosphere once it formed.. We discuss the data from the excursion and what we learn about the scale size of the comet magnetosphere as well as the energy transfer from the solar wind to the comet environment inside the comet magnetosphere. As comet 67P is now moving away from the sun, beginning in late December 2015 the solar wind has started to permeate the comet environment again. We compare this with the early data when comet 67P was approaching the sun, and discuss whether we see any asymmetries between a growing and waning comet magnetosphere.

  7. Plasma Boundaries and Kinetic-Scale Electric Field Structures in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Malaspina, David; Larsen, Brian; Ergun, R. E.; Skoug, Ruth; Wygant, John; Reeves, Geoffrey; Jaynes, Allison

    2016-07-01

    Recent advances in spacecraft instrumentation have enabled fresh examination of coupling between macro-scale and micro-scale physics in the terrestrial magnetosphere, demonstrating not only that cross-scale interactions are a key component of magnetospheric dynamics, but also that plasma boundaries play a crucial role in mediating cross-scale coupling. We use Van Allen Probe observations to study the cross-scale interaction between inner magnetospheric plasma boundaries (including the plasmapause and injection fronts) and kinetic-scale electric field structures including kinetic Alfven waves, double layers, phase space holes, and nonlinear whistler mode waves. We focus on the spatial distribution of these kinetic structures in the inner magnetosphere and their interaction with plasma boundaries. We demonstrate that both the occurrence probability and amplitude of these structures peak at plasma boundaries. Further, it is found that regions of kinetic-scale electric field structure activity travel with plasma boundaries. These observations imply that kinetic-scale electric field structures are continually generated by instabilities localized to these boundaries, constraining their ability to energize radiation belt particles over large spatial regions.

  8. Sedimentation and polar order of active bottom-heavy particles.

    PubMed

    Wolff, Katrin; Hahn, Aljoscha M; Stark, Holger

    2013-04-01

    Self-propelled particles in an external gravitational field have been shown to display both an increased sedimentation length and polar order even without particle interactions. Here, we investigate self-propelled particles which additionally are bottom-heavy, that is they feel a torque aligning them to swim against the gravitational field. For bottom-heavy particles the gravitational field has the two opposite effects of i) sedimentation and ii) upward alignment of the particles' swimming direction. We perform a multipole expansion of the one-particle distribution of non-interacting particles with respect to orientation and derive expressions for sedimentation length and mean particle orientation which we check against Brownian Dynamics simulations. For large strength of gravity or small particle speeds and aligning torque, we observe sedimentation with increased sedimentation length compared with passive colloids but also active colloids without bottom-heaviness. Increasing, for example, swimming speed the sedimentation profile is inverted and the particles swim towards the top wall of the enclosing box. We find maximal orientational order at intermediate swimming speeds for both cases of particles with bottom-heaviness and those without. Ordering unsurprisingly is increased for the bottom-heavy particles, but this difference disappears at higher levels of activity and for very high activities ordering goes to zero in both cases. PMID:23612748

  9. Global problems in magnetospheric plasma physics and prospects for their solution

    NASA Technical Reports Server (NTRS)

    Roederer, J. G.

    1977-01-01

    Selected problems in magnetospheric plasma physics are critically reviewed. The discussion is restricted to questions that are 'global' in nature (i.e., involve the magnetosphere as a whole) and that are beyond the stage of systematic survey or isolated study requirements. Only low-energy particle aspects are discussed. The article focuses on the following subjects: (1) the effect of the interplanetary magnetic field on the topography, topology, and stability of the magnetospheric boundary; (2) solar-wind plasma entry into the magnetosphere; (3) plasma storage and release mechanisms in the magnetospheric tail; and (4) magnetic-field-aligned currents and magnetosphere-ionosphere interactions. A brief discussion of the prospects for the solution of these problems during and after the International Magnetospheric Study is given.

  10. Magnetosphere of Mercury

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1975-01-01

    A model magnetosphere of Mercury using Mariner 10 data is presented. Diagrams of the bow shock wave and magnetopause are shown. The analysis of Mariner 10 data indicates that the magnetic field of the planet is intrinsic. The magnetic tail and secondary magnetic fields, and the influence of the solar wind are also discussed.

  11. New magnetospheric results from the SAMPEX mission

    SciTech Connect

    Baker, D.N.; Blake, J.B.; Callis, L.B.; Hovestadt, D.; Kanekal, S.; Mewaldt, R.A.; Nakamura, R.

    1996-07-01

    Results are described from energetic particle detectors onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite. Electron data are shown for energies {ital E}{gt}400 keV in the outer zone of electron trapping ({ital L}{approx_gt}3). The processes by which electrons are accelerated to very high energies ({ital E}{gt}1 MeV) are discussed. Data are sorted according to {ital L}-values and are compared with concurrent solar wind and geomagnetic conditions. Data from SAMPEX are also compared to GOES and UARS measurements. It is found that high-speed solar wind streams drive the acceleration and recirculation of electrons throughout the outer zone on time scales of one day (or less). Very high time resolution measurements from SAMPEX show the very sporadic nature of magnetosphere-atmosphere coupling processes. {copyright} {ital 1996 American Institute of Physics.}

  12. Phenomenology of magnetospheric radio emissions

    NASA Technical Reports Server (NTRS)

    Carr, T. D.; Desch, M. D.; Alexander, J. K.

    1983-01-01

    Jupiter has now been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz. Its radio emissions fill the entire spectral region where interplanetary electromagnetic propagation is possible at wavelengths longer than infrared. Three distinct types of radiation are responsible for this radio spectrum. Thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end. Synchrotron emission from the trapped high-energy particle belt deep within the inner magnetosphere is the dominant spectral component from about 4000 to 40 MHz. The third class of radiation consists of several distinct components of sporadic low frequency emission below 40 MHz. The decimeter wavelength emission is considered, taking into account the discovery of synchrotron emission, radiation by high-energy electrons in a magnetic field, and the present status of Jovian synchrotron phenomenology. Attention is also given to the decameter and hectometer wavelength emission, and emissions at kilometric wavelengths.

  13. Pair-Starved Pulsar Magnetospheres

    NASA Technical Reports Server (NTRS)

    Muslimov, Alex G.; Harding, Alice K.

    2009-01-01

    We propose a simple analytic model for the innermost (within the light cylinder of canonical radius, approx. c/Omega) structure of open-magnetic-field lines of a rotating neutron star (NS) with relativistic outflow of charged particles (electrons/positrons) and arbitrary angle between the NS spin and magnetic axes. We present the self-consistent solution of Maxwell's equations for the magnetic field and electric current in the pair-starved regime where the density of electron-positron plasma generated above the pulsar polar cap is not sufficient to completely screen the accelerating electric field and thus establish thee E . B = 0 condition above the pair-formation front up to the very high altitudes within the light cylinder. The proposed mode1 may provide a theoretical framework for developing the refined model of the global pair-starved pulsar magnetosphere.

  14. Stochastic dynamics of coupled active particles in an overdamped limit

    NASA Astrophysics Data System (ADS)

    Ann, Minjung; Lee, Kong-Ju-Bock; Park, Pyeong Jun

    2015-10-01

    We introduce a model for Brownian dynamics of coupled active particles in an overdamped limit. Our system consists of several identical active particles and one passive particle. Each active particle is elastically coupled to the passive particle and there is no direct coupling among the active particles. We investigate the dynamics of the system with respect to the number of active particles, viscous friction, and coupling between the active and passive particles. For this purpose, we consider an intracellular transport process as an application of our model and perform a Brownian dynamics simulation using realistic parameters for processive molecular motors such as kinesin-1. We determine an adequate energy conversion function for molecular motors and study the dynamics of intracellular transport by multiple motors. The results show that the average velocity of the coupled system is not affected by the number of active motors and that the stall force increases linearly as the number of motors increases. Our results are consistent with well-known experimental observations. We also examine the effects of coupling between the motors and the cargo, as well as of the spatial distribution of the motors around the cargo. Our model might provide a physical explanation of the cooperation among active motors in the cellular transport processes.

  15. From discovery to prediction of magnetospheric processes

    NASA Astrophysics Data System (ADS)

    Kamide, Y.

    2000-11-01

    Over the last 50 years magnetospheric research has transferred its focus from geomagnetism to space physics, or from inferring the intensity of extraterrestrial currents, through discoveries of the main plasma regions in the magnetosphere, to predicting the processes occurring in the entire solar wind-magnetosphere-ionosphere system. Relating advances in magnetospheric physics to the framework of substorm research, this review paper demonstrates that the ``recent'' space age since 1960s consisted of /(1) an exploratory//discovery phase in which the magnetotail, the plasma sheet, and the acceleration region of auroral particles were identified, and /(2) a phase of comprehensive understanding in which we have attempted to comprehend the nature and significance of the near-Earth space environment. This progress in solar-terrestrial physics has coincided with a number of new discoveries of solar and interplanetary phenomena such as magnetic clouds, coronal mass ejections and coronal holes. Computer simulation techniques have been developed to the degree that satellite observations from a very limited number of points can be used to trace and reproduce the main energy processes. We are now entering a new phase in which we hope to be able to predict the dynamic processes that take place in the solar-terrestrial environment.

  16. Kelvin Helmholtz Instability in Planetary Magnetospheres

    NASA Astrophysics Data System (ADS)

    Johnson, Jay R.; Wing, Simon; Delamere, Peter A.

    2014-11-01

    Kelvin-Helmholtz instability plays a particularly important role in plasma transport at magnetospheric boundaries because it can control the development of a turbulent boundary layer, which governs the transport of mass, momentum, and energy across the boundary. Waves generated at the interface can also couple into body modes in the plasma sheet and inner magnetosphere where they can play an important role in plasma sheet transport and particle energization in the inner magnetosphere. Kinetic and electron-scale effects are important for the development of K-H instability, leading to secondary instabilities and plasma mixing. The development of vortices that entwine magnetosheath field lines with magnetospheric field lines also allows reconnection and the interchange of plasma blobs from open to closed field lines. Dawn-dusk asymmetries in Kelvin-Helmholtz development at planetary boundary layers may result from several effects including plasma corotation, kinetic effects, magnetic geometry, or asymmetric distribution of plasma. Examples are provided throughout the solar system illustrating the pervasive effects of the Kelvin-Helmholtz instability on plasma transport.

  17. Energetic electron observations of Rhea's magnetospheric interaction

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Krupp, N.; Kollmann, P.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.

    2011-10-01

    More specifically, we show results of a phase-space density analysis, looking for evidence of energetic electron transport processes in the vicinity of Rhea's wake. We also perform energetic electron trajectory tracings in order to map regions where access of energetic electrons in Rhea's interaction region is forbidden. Such regions form because of complex energetic particle magnetic drifts downstream of Rhea, where the magnetospheric electric and magnetic fields are disturbed. We show that while our approach provides some qualitative explanation for some of the observations of electrons with energies above 100 keV, the lowest energy features in the MIMI/LEMMS dataset (20-100 keV) cannot be explained, especially those that extend upstream of Rhea and in a region that a plasma absorbing moon should, in theory, have no effect on the magnetospheric populations. Given that, in addition to the fact that Rhea orbits in a region of the magnetosphere that is thought be unstable against centrifugal interchange, we propose that the formation of Rhea's wake acts as a disturbance that helps enhance local magnetospheric interchange. Interchange driven disturbances, may then actually be the source of some of the unusual energetic electron observations. We also discuss this scenario in the context of additional published observations by the Cassini's cold plasma detector.

  18. The pulsating magnetosphere and flux transfer events

    SciTech Connect

    Potemra, T.A.; Zanetti, L.J. ); Elphinstone, R.; Murphree, J.S. ); Klumpar, D.M. )

    1992-08-03

    A unique positioning of the GOES 5, GOES 6, AMPTE/CCE, and Viking satellites on the dayside of the magnetosphere has provided the opportunity to study the relationship of periodic variations in magnetic fields, energetic particle fluxes, and images of UV auroral forms. On March 25, 1986, at about 1725 UT, two cycles of 10-min-period magnetic field oscillations were observed by all four satellites and by the Huancayo magnetic ground station. The UV images acquired by Viking showed intense emissions in a wide area near noon at 1730 UT, but near dawn 11 min. later. The authors interpret these observations as being associated with anti-sunward-moving periodic compressions of the magnetopause, which precipitated low-energy electrons that produced the enhanced UV emissions. In the midst of the longer-period variations, the magnetic field intensity measured by CCE near the magnetopause decreased sharply for a 105-sec period. This may be interpreted as being due to a flux transfer event that occurred during the longer (10-min) periodic compressions of the magnetosphere. These observations support the view that the magnetosphere often varies in a periodic way because of its own resonant processes and processes driven by the solar wind. A wide range of phenomena is associated with these variations including dayside auroral emissions, magnetic field variations throughout the magnetosphere and on the Earth's surface, and flux transfer events.

  19. The Magnetospheric Multiscale (MMS) Mission Science Data Center: Technologies, Methods, and Experiences in Making Available Large Volumes of In-Situ Particle and Field Data

    NASA Astrophysics Data System (ADS)

    Pankratz, Christopher; Kokkonen, Kim; Larsen, Kristopher; Panneton, Russell; Putnam, Brian; Schafer, Corey; Baker, Daniel; Burch, James

    2016-04-01

    On September 1, 2015 the Magnetospheric MultiScale (MMS) constellation of four satellites completed their six-month commissioning period and began routine science data collection. Science operations for the mission is conducted at the Science Operations Center (SOC) at the Laboratory for Atmospheric and Space Physics, University of Colorado in Boulder, Colorado, USA. The MMS Science Data Center (SDC) is a component of the SOC responsible for the data production, management, dissemination, archiving, and visualization of the data from the extensive suite of 100 instruments onboard the four spacecraft. As of March 2016, MMS science data are openly available to the entire science community via the SDC. This includes hundreds of science parameters, and 50 gigabytes of data per day distributed across thousands of data files. Products are produced using integrated software systems developed and maintained by teams at other institutions using their own institutional software management procedures and made available via a centralized public web site and web services. To accomplish the data management, data processing, and system integration challenges present on this space mission, the MMS SDC incorporates a number of evolutionary techniques and technologies. This presentation will provide an informatics-oriented view of the MMS SDC, summarizing its technical aspects, novel technologies and data management practices that are employed, experiences with its design and development, and lessons learned. Also presented is the MMS "Scientist-in-the-Loop" (SITL) system, which is used to leverage human insight and expertise to optimize the data selected for transmission to the ground. This smoothly operating system entails the seamless interoperability of multiple mission facilities and data systems that ultimately translate scientist insight into uplink commands that triggers optimal data downlink to the ground.

  20. Stochastic thermodynamics of active Brownian particles

    NASA Astrophysics Data System (ADS)

    Ganguly, Chandrima; Chaudhuri, Debasish

    2013-09-01

    Examples of self-propulsion in strongly fluctuating environments are abundant in nature, e.g., molecular motors and pumps operating in living cells. Starting from the Langevin equation of motion, we develop a stochastic thermodynamic description of noninteracting self-propelled particles using simple models of velocity-dependent forces. We derive fluctuation theorems for entropy production and a modified fluctuation-dissipation relation, characterizing the linear response in nonequilibrium steady states. We study these notions in a simple model of molecular motors, and in the Rayleigh-Helmholtz and energy-depot models of self-propelled particles.

  1. Magnetospheric Substorms and Tail Dynamics

    NASA Technical Reports Server (NTRS)

    Hughes, W. Jeffrey

    1998-01-01

    This grant funded several studies of magnetospheric substorms and their effect on the dynamics of the earth's geomagnetic tail. We completed an extensive study of plasmoids, plasma/magnetic field structures that travel rapidly down the tail, using data from the ISEE 3 and IMP 8 spacecraft. This study formed the PhD thesis of Mark Moldwin. We found that magnetically plasmoids are better described as flux-ropes (twisted magnetic flux tubes) rather than plasma bubbles, as had been generally regarded up to that point (Moldwin and Hughes, 1990; 1991). We published several examples of plasmoids observed first in the near tail by IMP 8 and later in the distant tail by ISEE 3, confirming their velocities down tail. We showed how the passage of plasmoids distorts the plasma sheet. We completed the first extensive statistical survey of plasmoids that showed how plasmoids evolve as they move down tail from their formation around 30 RE to ISEE 3 apogee at 240 RE. We established a one-to-one correspondence between the observation of plasmoids in the distant tail and substorm onsets at earth or in the near tail. And we showed that there is a class of plasmoid-like structures that move slowly earthward, especially following weak substorms during northward IMF. Collectively this work constituted the most extensive study of plasmoids prior to the work that has now been done with the GEOTAIL spacecraft. Following our work on plasmoids, we turned our attention to signatures of substorm onset observed in the inner magnetosphere near geosynchronous orbit, especially signatures observed by the CRRES satellite. Using data from the magnetometer, electric field probe, plasma wave instrument, and low energy plasma instrument on CRRES we were able to better document substorm onsets in the inner magnetosphere than had been possible previously. Detailed calculation of the Poynting flux showed energy exchange between the magnetosphere and ionosphere, and a short burst of tailward convective

  2. Research in particles and fields in space

    NASA Technical Reports Server (NTRS)

    Coleman, P. J., Jr.

    1973-01-01

    Theoretical and experimental work in charged particle and magnetic field research is reported. Activities center on plasma generation and acceleration, ATS 1 data processing for evaluation of magnetospheric substorms and micropulsations during magnetic disturbances, and the development of solar wind model using Mariner observations.

  3. Remote Control of T Cell Activation Using Magnetic Janus Particles.

    PubMed

    Lee, Kwahun; Yi, Yi; Yu, Yan

    2016-06-20

    We report a strategy for using magnetic Janus microparticles to control the stimulation of T cell signaling with single-cell precision. To achieve this, we designed Janus particles that are magnetically responsive on one hemisphere and stimulatory to T cells on the other side. By manipulating the rotation and locomotion of Janus particles under an external magnetic field, we could control the orientation of the particle-cell recognition and thereby the initiation of T cell activation. This study demonstrates a step towards employing anisotropic material properties of Janus particles to control single-cell activities without the need of complex magnetic manipulation devices. PMID:27144475

  4. Entropic Ratchet transport of interacting active Brownian particles

    SciTech Connect

    Ai, Bao-Quan; He, Ya-Feng; Zhong, Wei-Rong

    2014-11-21

    Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction.

  5. Hysteretic dynamics of active particles in a periodic orienting field

    PubMed Central

    Romensky, Maksym; Scholz, Dimitri; Lobaskin, Vladimir

    2015-01-01

    Active motion of living organisms and artificial self-propelling particles has been an area of intense research at the interface of biology, chemistry and physics. Significant progress in understanding these phenomena has been related to the observation that dynamic self-organization in active systems has much in common with ordering in equilibrium condensed matter such as spontaneous magnetization in ferromagnets. The velocities of active particles may behave similar to magnetic dipoles and develop global alignment, although interactions between the individuals might be completely different. In this work, we show that the dynamics of active particles in external fields can also be described in a way that resembles equilibrium condensed matter. It follows simple general laws, which are independent of the microscopic details of the system. The dynamics is revealed through hysteresis of the mean velocity of active particles subjected to a periodic orienting field. The hysteresis is measured in computer simulations and experiments on unicellular organisms. We find that the ability of the particles to follow the field scales with the ratio of the field variation period to the particles' orientational relaxation time, which, in turn, is related to the particle self-propulsion power and the energy dissipation rate. The collective behaviour of the particles due to aligning interactions manifests itself at low frequencies via increased persistence of the swarm motion when compared with motion of an individual. By contrast, at high field frequencies, the active group fails to develop the alignment and tends to behave like a set of independent individuals even in the presence of interactions. We also report on asymptotic laws for the hysteretic dynamics of active particles, which resemble those in magnetic systems. The generality of the assumptions in the underlying model suggests that the observed laws might apply to a variety of dynamic phenomena from the motion of

  6. Hysteretic dynamics of active particles in a periodic orienting field.

    PubMed

    Romensky, Maksym; Scholz, Dimitri; Lobaskin, Vladimir

    2015-07-01

    Active motion of living organisms and artificial self-propelling particles has been an area of intense research at the interface of biology, chemistry and physics. Significant progress in understanding these phenomena has been related to the observation that dynamic self-organization in active systems has much in common with ordering in equilibrium condensed matter such as spontaneous magnetization in ferromagnets. The velocities of active particles may behave similar to magnetic dipoles and develop global alignment, although interactions between the individuals might be completely different. In this work, we show that the dynamics of active particles in external fields can also be described in a way that resembles equilibrium condensed matter. It follows simple general laws, which are independent of the microscopic details of the system. The dynamics is revealed through hysteresis of the mean velocity of active particles subjected to a periodic orienting field. The hysteresis is measured in computer simulations and experiments on unicellular organisms. We find that the ability of the particles to follow the field scales with the ratio of the field variation period to the particles' orientational relaxation time, which, in turn, is related to the particle self-propulsion power and the energy dissipation rate. The collective behaviour of the particles due to aligning interactions manifests itself at low frequencies via increased persistence of the swarm motion when compared with motion of an individual. By contrast, at high field frequencies, the active group fails to develop the alignment and tends to behave like a set of independent individuals even in the presence of interactions. We also report on asymptotic laws for the hysteretic dynamics of active particles, which resemble those in magnetic systems. The generality of the assumptions in the underlying model suggests that the observed laws might apply to a variety of dynamic phenomena from the motion of

  7. Active microrheology of driven granular particles.

    PubMed

    Wang, Ting; Grob, Matthias; Zippelius, Annette; Sperl, Matthias

    2014-04-01

    When pulling a particle in a driven granular fluid with constant force Fex, the probe particle approaches a steady-state average velocity v. This velocity and the corresponding friction coefficient of the probe ζ=Fex/v are obtained within a schematic model of mode-coupling theory and compared to results from event-driven simulations. For small and moderate drag forces, the model describes the simulation results successfully for both the linear as well as the nonlinear region: The linear response regime (constant friction) for small drag forces is followed by shear thinning (decreasing friction) for moderate forces. For large forces, the model demonstrates a subsequent increasing friction in qualitative agreement with the data. The square-root increase of the friction with force found in [Fiege et al., Granul. Matter 14, 247 (2012)] is explained by a simple kinetic theory. PMID:24827243

  8. Pioneer 10: Observations of energetic electrons in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Randall, B. A.

    1974-01-01

    Results are given of a study of the intensities, energy spectra, and angular distribution of energetic particles in the magnetosphere of Jupiter; the heliocentric radial gradient of the intensity of galactic cosmic rays; and the occurrence, intensity, and angular distribution of solar flare particles and their propagation through the interplanetary medium at large heliocentric distances.

  9. Multi-Scale Modeling of Magnetospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Kuznetsova, M. M.; Hesse, M.; Toth, G.

    2012-01-01

    Magnetic reconnection is a key element in many phenomena in space plasma, e.g. Coronal mass Ejections, Magnetosphere substorms. One of the major challenges in modeling the dynamics of large-scale systems involving magnetic reconnection is to quantifY the interaction between global evolution of the magnetosphere and microphysical kinetic processes in diffusion regions near reconnection sites. Recent advances in small-scale kinetic modeling of magnetic reconnection significantly improved our understanding of physical mechanisms controlling the dissipation in the vicinity of the reconnection site in collisionless plasma. However the progress in studies of small-scale geometries was not very helpful for large scale simulations. Global magnetosphere simulations usually include non-ideal processes in terms of numerical dissipation and/or ad hoc anomalous resistivity. Comparative studies of magnetic reconnection in small scale geometries demonstrated that MHD simulations that included non-ideal processes in terms of a resistive term 11 J did not produce fast reconnection rates observed in kinetic simulations. In collisionless magnetospheric plasma, the primary mechanism controlling the dissipation in the vicinity of the reconnection site is nongyrotropic pressure effects with spatial scales comparable with the particle Larmor radius. We utilize the global MHD code BATSRUS and replace ad hoc parameters such as "critical current density" and "anomalous resistivity" with a physically motivated model of dissipation. The primary mechanism controlling the dissipation in the vicinity of the reconnection site in incorporated into MHD description in terms of non-gyrotropic corrections to the induction equation. We will demonstrate that kinetic nongyrotropic effects can significantly alter the global magnetosphere evolution. Our approach allowed for the first time to model loading/unloading cycle in response to steady southward IMF driving. The role of solar wind parameters and

  10. Alfven Waves in the Solar Wind, Magnetosheath, and Outer Magnetosphere

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.

    2007-01-01

    Alfven waves Propagating outward from the Sun are ubiquitous in the solar wind and play a major role in the solar wind-magnetosphere interaction. The passage of the waves generally occurs in the form of a series of discrete steepened discontinuities, each of which results in an abrupt change in the interplanetary magnetic field direction. Some orientations of the magnetic field permit particles energized at the Earth's bow shock to gain access to the foreshock region immediately upstream from the Earth's bow shock. The thermal pressure associated with these particles can greatly perturb solar wind plasma and magnetic field parameters shortly prior to their interaction with the Earth's bow shock and magnetosphere. The corresponding dynamic pressure variations batter the magnetosphere, driving magnetopause motion and transient compressions of the magnetospheric magnetic field. Alfven waves transmit information concerning the dynamic pressure variations applied to the magnetosphere to the ionosphere, where they generate the traveling convection vortices (TCVs) seen in high-latitude ground magnetograms. Finally, the sense of Alfvenic perturbations transmitted into the magnetosheath reverses across local noon because magnetosheath magnetic field lines drape against the magnetopause. The corresponding change in velocity perturbations must apply a weak torque to the Earth's magnetosphere.

  11. Five Years of Stereo Magnetospheric Imaging by TWINS

    NASA Astrophysics Data System (ADS)

    Goldstein, J.; McComas, D. J.

    2013-12-01

    Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) is the first stereoscopic magnetospheric imager. TWINS is a NASA Explorer Mission of Opportunity performing simultaneous energetic neutral atom (ENA) imaging from two widely-separated Molniya orbits on two different spacecraft, and providing nearly continuous coverage of magnetospheric ENA emissions. The ENA imagers observe energetic neutrals produced from global ion populations, over a broad energy range (1-100 keV/u) with high angular (4∘×4∘) and time (about 1-minute) resolution. TWINS distinguishes hydrogen ENAs from oxygen ENAs. Each TWINS spacecraft also carries a Lyman- α geocoronal imager to monitor the cold exospheric hydrogen atoms that produce ENAs from ions via charge exchange. Complementing the imagers are detectors that measure the local charged particle environment around the spacecraft. During its first five years of science operations, TWINS has discovered new global properties of geospace plasmas and neutrals, fostered understanding of causal relationships, confirmed theories and predictions based on in situ data, and yielded key insights needed to improve geospace models. Analysis and modeling of TWINS data have: (1) obtained continuous (main phase through recovery) global ion spectra, (2) revealed a previously unknown local-time dependence of global pitch angle, (3) developed quantitative determination of ion fluxes from low altitude ENAs (4) determined dynamic connections between local pitch angle and global ion precipitation, (5) confirmed local-time dependence of precipitating ion temperature, (6) imaged global dynamic heating of the magnetosphere, (7) explained why the oxygen ring current survives longer into recovery than hydrogen, and (8) revealed new global exospheric density features and their influence upon ring current decay rates. Over the next several years of the solar cycle, TWINS observations of three-dimensional (3D) global ion dynamics, composition, origins and

  12. Mercury's Dynamic Magnetosphere: What Have We Learned from MESSENGER?

    NASA Astrophysics Data System (ADS)

    Slavin, James A.

    2016-04-01

    does Mercury's magnetosphere accelerate energetic charged particles?

  13. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-12-01

    Trapped by Earth's magnetic field far above the planet's surface, the energetic particles that fill the radiation belts are a sign of the Sun's influence and a threat to our technological future. In the AGU monograph Dynamics of the Earth's Radiation Belts and Inner Magnetosphere, editors Danny Summers, Ian R. Mann, Daniel N. Baker, and Michael Schulz explore the inner workings of the magnetosphere. The book reviews current knowledge of the magnetosphere and recent research results and sets the stage for the work currently being done by NASA's Van Allen Probes (formerly known as the Radiation Belt Storm Probes). In this interview, Eos talks to Summers about magnetospheric research, whistler mode waves, solar storms, and the effects of the radiation belts on Earth.

  14. The Jovian magnetosphere - A post-Voyager view

    NASA Astrophysics Data System (ADS)

    Hill, T. W.

    1981-01-01

    Results of observational and theoretical work presented at the Rice University Conference on the Physics of the Jovian Magnetosphere (February 27-29, 1980) are summarized and used to elucidate the post-Voyager status of the understanding of Jovian magnetosphere dynamics. Works considered treat earth-based and Voyager observations of the Io torus, decametric and kilometric radio emissions, corotation of magnetospheric plasma with the magnetic field, and theoretical studies of mechanisms of particle acceleration, diffusion and loss in the magnetosphere and interplanetary space. Issues remaining to be resolved by future research are also indicated, particularly questions of the discrepancy between plasma flow measurements obtained on the two plasma experiments on each Voyager spacecraft, and the localization of the source of torus plasma.

  15. Currents in Saturn's magnetosphere

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.; Acuna, M. H.; Ness, N. F.

    1983-01-01

    A model of Saturn's magnetospheric magnetic field is obtained from the Voyager 1 and 2 observations. A representation consisting of the Z sub 3 zonal harmonic model of Saturn's planetary magnetic field together with an explicit model of Saturn's planetary magnetic field and a model of the equatorial ring current fits the observations well within r 20 R sub S, with the exception of data obtained during the Voyager 2 inbound pass.

  16. Plasmas in Saturn's magnetosphere

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Burek, B. G.; Ackerson, K. L.; Wolfe, J. H.; Mihalov, J. D.

    1980-01-01

    The solar wind plasma analyzer on board Pioneer 2 provides first observations of low-energy positive ions in the magnetosphere of Saturn. Measurable intensities of ions within the energy-per-unit charge (E/Q) range 100 eV to 8 keV are present over the planetocentric radial distance range about 4 to 16 R sub S in the dayside magnetosphere. The plasmas are found to be rigidly corotating with the planet out to distances of at least 10 R sub S. At radial distances beyond 10 R sub S, the bulk flows appear to be in the corotation direction but with lesser speeds than those expected from rigid corotation. At radial distances beyond the orbit of Rhea at 8.8 R sub S, the dominant ions are most likely protons and the corresponding typical densities and temperatures are 0.5/cu cm and 1,000,000 K, respectively, with substantial fluctuations. It is concluded that the most likely source of these plasmas in the photodissociation of water frost on the surface of the ring material with subsequent ionization of the products and radially outward diffusion. The presence of this plasma torus is expected to have a large influence on the dynamics of Saturn's magnetosphere since the pressure ratio beta of these plasmas approaches unity at radial distances as close to the planet as 6.5 R sub S. On the basis of these observational evidences it is anticipated that quasi-periodic outward flows of plasma, accompanied with a reconfiguration of the magnetosphere beyond about 6.5 R sub S, will occur in the local night sector in order to relieve the plasma pressure from accretion of plasma from the rings.

  17. Is Saturn's Magnetosphere Turbulent?

    NASA Astrophysics Data System (ADS)

    Walker, Raymond; Fukazawa, Keiichiro; Eriksson, Stefan; Weygand, James

    2016-04-01

    On February 12, 2008 the Cassini spacecraft passed through Saturn's dayside bow shock and spent 16 hours in the solar wind. The interval in the solar wind was characterized by a series of dynamic pressure pulses and a rotation of the interplanetary magnetic field from southward to northward. We have used these Cassini solar observations to drive our global magnetohydrodynamic simulation of the interaction of solar wind with Saturn's magnetosphere and ionosphere. We found that large amplitude waves formed at the magnetopause in response to the changes in the dynamic pressure. The vorticity (both parallel and perpendicular) increased within the outer magnetosphere. The vorticity was mostly driven by pressure variations and not reconnection. The vortices frequently were nested with smaller vortices within the large scale vortices. This cascade in vorticity is suggestive of turbulent flows. In this presentation we will evaluate vorticity in our Saturn simulation to determine if the flows are turbulent. With Cassini in the solar wind there were no simultaneous observations within Saturn's magnetosphere. However we will examine the Cassini observations at other times to look for evidence of turbulence.

  18. Magnetosphere-ionosphere waves

    NASA Astrophysics Data System (ADS)

    Russell, A. J. B.; Wright, A. N.

    2012-01-01

    Self-consistent electrodynamic coupling of the ionosphere and magnetosphere produces waves with clearly defined properties, described here for the first time. Large scale (ideal) disturbances to the equilibrium, for which electron inertia is unimportant, move in the direction of the electric field at a characteristic speed. This may be as fast as several hundred meters per second or approximately half the E × B drift speed. In contrast, narrow scale (strongly inertial) waves are nearly stationary and oscillate at a specific frequency. Estimates of this frequency suggest periods from several tenths of a second to several minutes may be typical. Both the advection speed and frequency of oscillation are derived for a simple model and depend on a combination of ionospheric and magnetospheric parameters. Advection of large scale waves is nonlinear: troughs in E-region number density move faster than crests and this causes waves to break on their trailing edge. Wavebreaking is a very efficient mechanism for producing narrow (inertial) scale waves in the coupled system, readily accessing scales of a few hundred meters in just a few minutes. All magnetosphere-ionosphere waves are damped by recombination in the E-region, suggesting that they are to be best observed at night and in regions of low ionospheric plasma density. Links with observations, previous numerical studies and ionospheric feedback instability are discussed, and we propose key features of experiments that would test the new theory.

  19. On transpolar arc formation correlated with solar wind entry at high latitude magnetosphere

    NASA Astrophysics Data System (ADS)

    Mailyan, B. G.; Shi, Q.; Maggiolo, R.; Zong, Q.; Fu, S.; Zhang, Y.; Yao, Z.; Sun, W.

    2014-12-01

    Recently, Cluster observations revealed the existence of new regions of solar wind plasma entry at the high latitudes of the Earth's magnetosphere, at the lobes tailward of the cusp region, mostly during periods of northward IMF. Such periods of northward IMF are associated with the presence of transpolar arcs. Observations from Global Ultraviolet Imager (GUVI) instrument onboard TIMED spacecraft are used to investigate a possible link between solar wind entry in the high latitude magnetosphere and the formation of transpolar arcs. Data from IMAGE and DMSP spacecraft are also used to investigate the time evolution and particle characteristics of the transpolar arc.We present a case study of a theta aurora correlated with the solar wind entry. The observations show a simultaneous occurrence of aurora activity at the magnetotail and high latitudes, suggesting two-part structure of the apparent continuous band of the transpolar arc.

  20. Towards a Realistic Pulsar Magnetosphere

    NASA Technical Reports Server (NTRS)

    Kalapotharakos, Constantinos; Kazanas, Demosthenes; Harding, Alice; Contopoulos, Ioannis

    2012-01-01

    We present the magnetic and electric field structures as well as the currents ami charge densities of pulsar magnetospberes which do not obey the ideal condition, E(raised dot) B = O. Since the acceleration of particles and the production of radiation requires the presence of an electric field component parallel to the magnetic field, E(sub ll) the structure of non-Ideal pulsar magnetospheres is intimately related to the production of pulsar radiation. Therefore, knowledge of the structure of non-Ideal pulsar maglletospheres is important because their comparison (including models for t he production of radiation) with observations will delineate the physics and the parameters underlying the pulsar radiation problem. We implement a variety of prescriptions that support nonzero values for E(sub ll) and explore their effects on the structure of the resulting magnetospheres. We produce families of solutions that span the entire range between the vacuum and the (ideal) Force-Free Electrodynamic solutions. We also compute the amount of dissipation as a fraction of the Poynting flux for pulsars of different angles between the rotation and magnetic axes and conclude that tltis is at most 20-40% (depending on t he non-ideal prescription) in the aligned rotator and 10% in the perpendicular one. We present also the limiting solutions with the property J = pc and discuss their possible implicatioll on the determination of the "on/ off" states of the intermittent pulsars. Finally, we find that solutions with values of J greater than those needed to null E(sub ll) locally produce oscillations, potentially observable in the data.

  1. Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

    NASA Astrophysics Data System (ADS)

    Li, Hui-shu; Zhang, Bo-kai; Li, Jian; Tian, Wen-de; Chen, Kang

    2015-12-01

    The interaction between polymer brush and colloidal particles has been intensively studied in the last two decades. Here, we consider a flat chain-grafted substrate immersed in a bath of active particles. Simulations show that an increase in the self-propelling force causes an increase in the number of particles that penetrate into the brush. Anomalously, the particle density inside the main body of the brush eventually becomes higher than that outside the brush at very large self-propelling force. The grafted chains are further stretched due to the steric repulsion from the intruded particles. Upon the increase of the self-propelling force, distinct stretching behaviors of the chains were observed for low and high grafting densities. Surprisingly, we find a weak descent of the average end-to-end distance of chains at high grafting density and very large force which is reminiscent of the compression effect of a chain in the active bath.

  2. Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles.

    PubMed

    Li, Hui-shu; Zhang, Bo-kai; Li, Jian; Tian, Wen-de; Chen, Kang

    2015-12-14

    The interaction between polymer brush and colloidal particles has been intensively studied in the last two decades. Here, we consider a flat chain-grafted substrate immersed in a bath of active particles. Simulations show that an increase in the self-propelling force causes an increase in the number of particles that penetrate into the brush. Anomalously, the particle density inside the main body of the brush eventually becomes higher than that outside the brush at very large self-propelling force. The grafted chains are further stretched due to the steric repulsion from the intruded particles. Upon the increase of the self-propelling force, distinct stretching behaviors of the chains were observed for low and high grafting densities. Surprisingly, we find a weak descent of the average end-to-end distance of chains at high grafting density and very large force which is reminiscent of the compression effect of a chain in the active bath. PMID:26671400

  3. Additivity, density fluctuations, and nonequilibrium thermodynamics for active Brownian particles

    NASA Astrophysics Data System (ADS)

    Chakraborti, Subhadip; Mishra, Shradha; Pradhan, Punyabrata

    2016-05-01

    Using an additivity property, we study particle-number fluctuations in a system of interacting self-propelled particles, called active Brownian particles (ABPs), which consists of repulsive disks with random self-propulsion velocities. From a fluctuation-response relation, a direct consequence of additivity, we formulate a thermodynamic theory which captures the previously observed features of nonequilibrium phase transition in the ABPs from a homogeneous fluid phase to an inhomogeneous phase of coexisting gas and liquid. We substantiate the predictions of additivity by analytically calculating the subsystem particle-number distributions in the homogeneous fluid phase away from criticality where analytically obtained distributions are compatible with simulations in the ABPs.

  4. Magnetosphere, exosphere, and surface of Mercury

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Johnson, R. E.; Krimigis, S. M.; Lanzerotti, L. J.

    1987-09-01

    The discovery of an atomic sodium exosphere at Mercury raises the question of whether Mercury, like Io at Jupiter, can maintain a heavy ion magnetosphere. The authors suggest that it does, and that heavy ions (mainly Na+) from the exosphere are typically accelerated to keV energies and make important or dominant contributions to the mass (≡300 g sec-1) and energy (≡3×109W) budgets of the magnetosphere. The sodium supply to the exosphere is largely from within Mercury itself, with external sources like meteoroid infall and the solar wind being relatively unimportant. Therefore Mercury is in the process of losing its semivolatiles. Photosputtering dominates charged particle sputtering and can maintain an adequate rate of Na ejection from the surface.

  5. Cyclotron side band emissions from magnetospheric electrons

    NASA Technical Reports Server (NTRS)

    Maeda, K.

    1975-01-01

    Very low frequency emissions with subharmonic cyclotron frequency from magnetospheric electrons were detected by the S(3)-A satellite (Explorer 45) whose orbit is close to the magnetic equatorial plane where the wave-particle interaction is most efficient. These emissions were observed during the main phase of a geomagnetic storm in the nightside of the magnetosphere outside of the plasmasphere. During the event of these side-band emissions, the pitch angle distributions of high energy electrons (greater than 50 keV) and of energetic protons (greater than 100 keV) showed remarkable changes with time, whereas those of low energy electrons and protons remained approximately isotropic. In this type of event, emissions consist essentially of two bands, the one below the equatorial electron gyrofrequency, and the other above. The emissions below are whistler mode, and the emissions above are electrostatic mode.

  6. Overview - Electric fields. [in magnetosphere

    NASA Technical Reports Server (NTRS)

    Cauffman, D. P.

    1979-01-01

    The electric fields session is designed to review progress in observation, theory, and modeling of magnetospheric electric fields, and to expose important new results. The present report comments on the state and prospects of electric field research, with particular emphasis on relevance to quantitative modeling of the magnetospheric processes. Attention is given to underlying theories and models. Modeling philosophy is discussed relative to explanatory models and representative models. Modeling of magnetospheric electric fields, while in its infancy, is developing rapidly on many fronts employing a variety of approaches. The general topic of magnetospheric electric fields is becoming of prime importance in understanding space plasmas.

  7. Saturn: atmosphere, ionosphere, and magnetosphere.

    PubMed

    Gombosi, Tamas I; Ingersoll, Andrew P

    2010-03-19

    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and magnetosphere and briefly outlines the state of our knowledge after the Cassini prime mission. The mission has addressed a host of fundamental questions: What processes control the physics, chemistry, and dynamics of the atmosphere? Where does the magnetospheric plasma come from? What are the physical processes coupling the ionosphere and magnetosphere? And, what are the rotation rates of Saturn's atmosphere and magnetosphere? PMID:20299587

  8. Saturn's Magnetosphere, Rings, and Inner Satellites.

    PubMed

    VAN Allen, J A; Thomsen, M F; Randall, B A; Rairden, R L; Grosskreutz, C L

    1980-01-25

    Our 31 August to 5 September 1979 observations together with those of the other Pioneer 11 investigators provide the first credible discovery of the magnetosphere of Saturn and many detailed characteristics thereof. In physical dimensions and energetic charged particle population, Saturn's magnetosphere is intermediate between those of Earth and Jupiter. In terms of planetary radii, the scale of Saturn's magnetosphere more nearly resembles that of Earth and there is much less inflation by entrapped plasma than in the case at Jupiter. The orbit of Titan lies in the outer fringes of the magnetosphere. Particle angular distributions on the inbound leg of the trajectory (sunward side) have a complex pattern but are everywhere consistent with a dipolar magnetic field approximately perpendicular to the planet's equator. On the outbound leg (dawnside) there are marked departures from this situation outside of 7 Saturn radii (Rs), suggesting an equatorial current sheet having both longitudinal and radial components. The particulate rings and inner satellites have a profound effect on the distribution of energetic particles. We find (i) clear absorption signatures of Dione and Mimas; (ii) a broad absorption region encompassing the orbital radii of Tethys and Enceladus but probably attributable, at least in part, to plasma physical effects; (iii) no evidence for Janus (1966 S 1) (S 10) at or near 2.66 Rs; (iv) a satellite of diameter greater, similar 170 kilometers at 2.534 R(s) (1979 S 2), probably the same object as that detected optically by Pioneer 11 (1979 S 1) and previously by groundbased telescopes (1966 S 2) (S 11); (v) a satellite of comparable diameter at 2.343 Rs (1979 S 5); (vi) confirmation of the F ring between 2.336 and 2.371 Rs; (vii) confirmation of the Pioneer division between 2.292 and 2.336 Rs; (viii) a suspected satellite at 2.82 Rs (1979 S 3); (ix) no clear evidence for the E ring though its influence may be obscured by stronger effects; and (x) the

  9. Multidimensional stationary probability distribution for interacting active particles.

    PubMed

    Maggi, Claudio; Marconi, Umberto Marini Bettolo; Gnan, Nicoletta; Di Leonardo, Roberto

    2015-01-01

    We derive the stationary probability distribution for a non-equilibrium system composed by an arbitrary number of degrees of freedom that are subject to Gaussian colored noise and a conservative potential. This is based on a multidimensional version of the Unified Colored Noise Approximation. By comparing theory with numerical simulations we demonstrate that the theoretical probability density quantitatively describes the accumulation of active particles around repulsive obstacles. In particular, for two particles with repulsive interactions, the probability of close contact decreases when one of the two particle is pinned. Moreover, in the case of isotropic confining potentials, the radial density profile shows a non trivial scaling with radius. Finally we show that the theory well approximates the "pressure" generated by the active particles allowing to derive an equation of state for a system of non-interacting colored noise-driven particles. PMID:26021260

  10. Multiple-satellite studies of magnetospheric substorms: Plasma sheet recovery and the poleward leap of auroral-zone activity

    NASA Technical Reports Server (NTRS)

    Pytte, T.; Mcpherron, R. L.; Kivelson, M. G.; West, H. I., Jr.; Hones, E. W., Jr.

    1977-01-01

    Particle observations from pairs of satellites (Ogo 5, Vela 4A and 5B, Imp 3) during the recovery of plasma sheet thickness late in substorms were examined. Six of the nine events occurred within about 5 min in locations near the estimated position of the neutral sheet, but over wide ranges of east-west and radial separations. The time of occurrence and spatial extent of the recovery were related to the onset (defined by ground Pi 2 pulsations) and approximate location (estimated from ground mid-latitude magnetic signatures) of substorm expansions. It was found that the plasma sheet recovery occurred 10 - 30 min after the last in a series of Pi bursts, which were interpreted to indicate that the recovery was not due directly to a late, high latitude substorm expansion. The recovery was also observed to occur after the substorm current wedge had moved into the evening sector and to extend far to the east of the center of the last preceding substorm expansion.

  11. Magnetospheric environments of outer planet rings - Influence of Saturn's axially symmetric magnetic field

    NASA Technical Reports Server (NTRS)

    Hood, L. L.

    1987-01-01

    Saturn's main rings exist within a zone of negligible magnetospheric losses and surface alteration effects, substantially due to the solid-body absorption of inwardly diffusing magnetospheric particles. This process is presently shown to be especially efficient in the inner magnetosphere of Saturn, due to the near-axial symmetry of the planetary magnetic field relative to the equatorial rotation plane; under the assumption of comparable diffusion rates, the inward magnetospheric particle transport is far more inhibited in the inner Saturnian magnetosphere than in the same regions of Jupiter and Uranus, even when only rings of comparable widths and depths are considered. In light of this, ring particle surface exposure to the ion fluxes of the radiation belt remains a prepossessing rationale for low Uranian ring albedos.

  12. Magnetospheric environments of outer planet rings - influence of Saturn's axially symmetric magnetic field

    SciTech Connect

    Hood, L.L.

    1987-07-01

    Saturn's main rings exist within a zone of negligible magnetospheric losses and surface alteration effects, substantially due to the solid-body absorption of inwardly diffusing magnetospheric particles. This process is presently shown to be especially efficient in the inner magnetosphere of Saturn, due to the near-axial symmetry of the planetary magnetic field relative to the equatorial rotation plane; under the assumption of comparable diffusion rates, the inward magnetospheric particle transport is far more inhibited in the inner Saturnian magnetosphere than in the same regions of Jupiter and Uranus, even when only rings of comparable widths and depths are considered. In light of this, ring particle surface exposure to the ion fluxes of the radiation belt remains a prepossessing rationale for low Uranian ring albedos. 86 references.

  13. Huge light scattering from active anisotropic spherical particles.

    PubMed

    Fan, Xiaofeng; Shen, Zexiang; Luk'yanchuk, Boris

    2010-11-22

    The light scattering by a spherical particle with radial anisotropic permittivity ε and permeability μ are discussed in detail by expanding Mie theory. With the modified vector potential formulation, the electric anisotropy effects on scattering efficiency are addressed by studying the extinction, scattering, absorption and radar cross sections following the change of the transverse permittivity ε(t), the longitudinal permittivity ε(r) and the particle size q. The huge scattering cross sections are shown by considering the possible coupling between active medium and plasmon polaritons and this will be possible to result in spaser from the active plasmons of small particle. PMID:21164832

  14. The solar wind-magnetosphere energy coupling and magnetospheric disturbances

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1980-01-01

    Energy coupling between the solar wind and the magnetosphere is examined and the influence of this coupling on magnetospheric disturbances is discussed. Following a review of the components of the total energy production rate of the magnetosphere and progress in the study of solar wind-magnetosphere correlations, the derivation of the solar wind-magnetosphere energy coupling function, which has been found to correlate well with the total magnetospheric energy production rate, is presented. Examination of the relations between the energy coupling function and the type of magnetic disturbance with which it is associated indicates that magnetic storms with a large sudden storm commencement and a weak main phase are associated with small energy coupling, while values of the coupling function greater than 5 x 10 to the 18th to 10 to the 19th erg/sec are required for the development of a major geomagnetic storm. The magnetospheric substorm is shown to be a direct result of increased solar wind-magnetosphere energy coupling rather than the sudden conversion of stored magnetic energy. Finally, it is indicated that at energy couplings greater than 10 to the 19th erg/sec, the positive feedback process responsible for substorms breaks down, resulting in the abnormal growth of the ring current.

  15. MESSENGER observations of solar energetic electrons within Mercury's magnetosphere

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Anderson, Brian J.; Korth, Haje; Ho, George C.; Boardsen, Scott A.; Cassidy, Timothy A.; Walsh, Brian M.; Solomon, Sean C.

    2015-10-01

    During solar energetic particle (SEP) events, the inner heliosphere is bathed in MeV electrons. Through magnetic reconnection, these relativistic electrons can enter the magnetosphere of Mercury, nearly instantaneously filling the regions of open field lines with precipitating particles. With energies sufficient to penetrate solid aluminum shielding more than 1 mm thick, these electrons were observable by a number of sensors on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Because of its thin shielding, frequent sampling, and continuous temporal coverage, the Fast Imaging Plasma Spectrometer provided by far the most sensitive measurements of MeV electrons of all MESSENGER sensors. Sharp changes in energetic electron flux coincided with topological boundaries in the magnetosphere, including the magnetopause, polar cap, and central plasma sheet. Precipitating electrons with fluxes equal to ~40% of their corresponding upstream levels were measured over the entire polar cap, demonstrating that electron space weathering of Mercury's surface is not limited to the cusp region. We use these distinct precipitation signatures acquired over 33 orbits during 11 SEP events to map the full extent of Mercury's northern polar cap. We confirm a highly asymmetric polar cap, for which the dayside and nightside boundary latitudes range over ~50-70°N and ~30-60°N, respectively. These latitudinal ranges are consistent with average models of Mercury's magnetic field but exhibit a large variability indicative of active dayside and nightside magnetic reconnection processes. Finally, we observed enhanced electron fluxes within the central plasma sheet. Although these particles cannot form a stable ring current around the planet, their motion results in an apparent trapped electron population at low latitudes in the magnetotail.

  16. Nitrogen In Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Sittler, E. C.; Johnson, R. E.; McComas, D. J.; Reisenfeld, D.; Shappirio, M. D.; Baragiola, R.; Michael, M.; Shematovich, V. I.; Crary, F.; Young, D. T.

    2004-12-01

    We are analyzing CAPS instrument data on Cassini to look for nitrogen ions in Saturn's magnetosphere. Because Voyager could not separate oxygen and nitrogen, there has been considerable controversy on nitrogen's presence and relative importance. Two principal sources have been suggested: Titan's atmosphere and nitrogen species trapped in Saturn's icy satellite surfaces (Sittler et al 2004). The latter may be primordial nitrogen, likely as NH3 in ice (Stevenson 1982; Squyers et al. 1983) or nitrogen ions that have been implanted in the surface (Delitsky and Lane 2002). We will present the results of Saturnian nitrogen cloud modeling and relevant CAPS observations. We recently described the Titan source (Michael, et al. 2004; Shematovich et al. 2003; Smith et al. 2004; Sittler et al. 2004) in preparation for Cassini's Saturnian plasma measurements. Two components were identified: energetic nitrogen ions formed near Titan and energized as they diffused inward (Sittler et al. 2004) and neutrals in orbits with small perigee that became ionized in the inner magnetosphere (Smith et al 2004). The latter component would be a source of lower energy, co-rotating nitrogen ions in the inner magnetosphere. Such a component would have an energy spectrum similar to nitrogen species sputtered from the icy satellite surfaces (Johnson and Sittler 1990). However, the mass spectrum would differ, likely containing NHx and NOx species also, and, hence, may be separated from the Titan source. Our preliminary analysis for nitrogen species in the CAPS data will be compared to our models. Of interest will be the energy spectra, which can indicate whether any nitrogen present is formed locally or near Titan's orbit and diffused inward. This work is supported by the NASA Planetary Atmospheres, NASA Graduate Student Research, Virginia Space Grant Consortium Graduate Research Fellowship and CAPS Cassini instrument team programs.

  17. Ionospheric and magnetospheric 'plasmapauses'

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Maynard, N. C.; Hoffman, J. H.

    1978-01-01

    The locations of Explorer 45 plasmapause crossings are studied as a likely indicator of ionospheric and magnetospheric trough locations. Attention is given to vertical flows of H(+) ions in the light ion trough, as detected by the magnetic ion mass spectrometer aboard Isis 2 (which was operating in conjunction with Explorer 45 during August 1972). The possibility of an equatorial plasmapause is discussed, whose field lines map into the ionosphere at latitudes poleward of the H(+) density decrease, probably due to the refilling of magnetic flux tubes in the outer plasmasphere.

  18. Characterizing the Magnetospheric State for Sawtooth Events

    NASA Astrophysics Data System (ADS)

    Fung, S. F.; Tepper, J. A.; Cai, X.

    2015-12-01

    Magnetospheric sawtooth events, first identified in the early 1990's, are named for their characteristic appearance of multiple quasi-periodic intervals of slow decrease followed by sharp increase of proton energy fluxes in the geosynchronous region. The successive proton flux decrease-and-increase intervals have been interpreted as recurrences of stretching and dipolarization, respectively, of the nightside geomagnetic field [Reeves et al., 2003]. Due to their often-extended intervals with 2- 10 cycles, sawteeth occurrences are sometimes referred to as a magnetospheric mode [Henderson et al., 2006]. Studies over the past two decades of sawtooth events (both event and statistical) have yielded a wealth of information on the conditions for the onset and occurrence of sawtooth events, but the occurrences of sawtooth events during both storm and non-storm periods suggest that we still do not fully understand the true nature of sawtooth events [Cai et al., 2011]. In this study, we investigate the characteristic magnetospheric state conditions [Fung and Shao, 2008] associated with the beginning, during, and ending intervals of sawtooth events. Unlike previous studies of individual sawtooth event conditions, magnetospheric state conditions consider the combinations of both magnetospheric drivers (solar wind) and multiple geomagnetic responses. Our presentation will discuss the most probable conditions for a "sawtooth state" of the magnetosphere. ReferencesCai, X., J.-C. Zhang, C. R. Clauer, and M. W. Liemohn (2011), Relationship between sawtooth events and magnetic storms, J. Geophys. Res., 116, A07208, doi:10.1029/2010JA016310. Fung, S. F. and X. Shao, Specification of multiple geomagnetic responses to variable solar wind and IMF input, Ann. Geophys., 26, 639-652, 2008. Henderson, M. G., et al. (2006), Magnetospheric and auroral activity during the 18 April 2002 sawtooth event, J. Geophys. Res., 111, A01S90, doi:10.1029/2005JA011111. Reeves, G. D., et al. (2004), IMAGE

  19. Characterization of Magnetospheric Spacecraft Charging Environments Using the LANL Magnetospheric Plasma Analyzer Data Set

    NASA Technical Reports Server (NTRS)

    Hardage, Donna (Technical Monitor); Davis, V. A.; Mandell, M. J.; Thomsen, M. F.

    2003-01-01

    An improved specification of the plasma environment has been developed for use in modeling spacecraft charging. It was developed by statistically analyzing a large part of the LANL Magnetospheric Plasma Analyzer (MPA) data set for ion and electron spectral signature correlation with spacecraft charging, including anisotropies. The objective is to identify a relatively simple characterization of the full particle distributions that yield an accurate predication of the observed charging under a wide variety of conditions.

  20. Trajectories of charged particles trapped in Earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Öztürk, M. Kaan

    2012-05-01

    This article presents the theory of relativistic charged-particle motion in Earth's magnetosphere, at a level suitable for undergraduate courses. I discuss particle and guiding center motion and derive the three adiabatic invariants associated with the three periodic motions in a dipolar field. I provide 12 computational exercises that can be used as classroom assignments or for self-study. Two of the exercises, drift-shell bifurcation and Speiser orbits, are adapted from active magnetospheric research. The PYTHON code provided in the supplement can be used to replicate the trajectories and can be easily extended for different field geometries.

  1. Multi-Scale Modeling of Magnetospheric Reconnection

    NASA Technical Reports Server (NTRS)

    Kuznetsova, M. M.; Hesse, M.; Rastatter, L.; Toth, G.; Dezeeuw, D.; Gomobosi, T.

    2007-01-01

    One of the major challenges in modeling the magnetospheric magnetic reconnection is to quantify the interaction between large-scale global magnetospheric dynamics and microphysical processes in diffusion regions near reconnection sites. There is still considerable debate as to what degree microphysical processes on kinetic scales affect the global evolution and how important it is to substitute numerical dissipation and/or ad hoc anomalous resistivity by a physically motivated model of dissipation. Comparative studies of magnetic reconnection in small scale geometries demonstrated that MHD simulations that included non-ideal processes in terms of a resistive term $\\eta J$ did not produce the fast reconnection rates observed in kinetic simulations. For a broad range of physical parameters in collisionless magnetospheric plasma, the primary mechanism controlling the dissipation in the vicinity of the reconnection site is non-gyrotropic effects with spatial scales comparable with the particle Larmor radius. We utilize the global MHD code BATSRUS and incorporate nongyrotropic effects in diffusion regions in terms of corrections to the induction equation. We developed an algorithm to search for magnetotail reconnection sites, specifically where the magnetic field components perpendicular to the local current direction approaches zero and form an X-type configuration. Spatial scales of the diffusion region and magnitude of the reconnection electric field are calculated selfconsistently using MHD plasma and field parameters in the vicinity of the reconnection site. The location of the reconnection sites is updated during the simulations. To clarify the role of nongyrotropic effects in diffusion region on the global magnetospheric dynamic we perform simulations with steady southward IMF driving of the magnetosphere. Ideal MHD simulations with magnetic reconnection supported by numerical resistivity produce steady configuration with almost stationary near-earth neutral

  2. Path of the solar wind energy into the Earth s magnetosphere

    NASA Astrophysics Data System (ADS)

    Alexeev, I.

    The solar wind MHD generator is an unique energy source for all magnetospheric processes. The field-aligned currents directly transport the energy and momentum of the solar wind plasma to the Earth's ionosphere. The magnetospheric lobe and plasma sheet convection generated by the solar wind is another magnetospheric energy source. Plasma sheet particles and cold ionospheric polar wind ions are accelerated by convection electric field in the nightside magnetosphere. After energetic particle precipitation into upper atmosphere the premier solar wind energy transfer into ionosphere and atmosphere. This way of energy transfer can include the tail lobe magnetic field energy storage connected with the increasing of the tail current during southward IMF. After that the magnetospheric substorm occurs. The model calculations of the magnetospheric energy give possibility to determine the ground state of the magnetosphere, and to calculate relative contributions of tail currents, ring currents and field--aligned currents to the magnetospheric energy as well as the contributions to onground magnetic disturbances. The magnetospheric substorms and storms manifest that the permanent solar wind energy transfer ways are not enough for covering of solar wind energy input into the magnetosphere. Nonlinear explosive processes are necessary for energy transmission into ionosphere and atmosphere. Main conclusion tell us that the field--aligned currents are important contributors to magnetospheric energy transformations. For understanding a relation between substorms and storm it is necessary to take into account that both of them are the concurrent energy transferring ways. To test of the model' results a magnetospheric response to the CME-driven shocks that impinged on the Earth's magnetopause on 10 January 1997 and 28 September 1998 are studied.

  3. Strongly Accelerated Margination of Active Particles in Blood Flow.

    PubMed

    Gekle, Stephan

    2016-01-19

    Synthetic nanoparticles and other stiff objects injected into a blood vessel filled with red blood cells are known to marginate toward the vessel walls. By means of hydrodynamic lattice-Boltzmann simulations, we show that active particles can strongly accelerate their margination by moving against the flow direction: particles located initially in the channel center migrate much faster to their final position near the wall than in the nonactive case. We explain our findings by an enhanced rate of collisions between the stiff particles and the deformable red blood cells. Our results imply that a significantly faster margination can be achieved either technically by the application of an external magnetic field (if the particles are magnetic) or biologically by self-propulsion (if the particles are, e.g., swimming bacteria). PMID:26789773

  4. Guiding Catalytically Active Particles with Chemically Patterned Surfaces

    NASA Astrophysics Data System (ADS)

    Uspal, W. E.; Popescu, M. N.; Dietrich, S.; Tasinkevych, M.

    2016-07-01

    Catalytically active Janus particles suspended in solution create gradients in the chemical composition of the solution along their surfaces, as well as along any nearby container walls. The former leads to self-phoresis, while the latter gives rise to chemiosmosis, providing an additional contribution to self-motility. Chemiosmosis strongly depends on the molecular interactions between the diffusing chemical species and the wall. We show analytically, using an approximate "point-particle" approach, that by chemically patterning a planar substrate one can direct the motion of Janus particles: the induced chemiosmotic flows can cause particles to either "dock" at the chemical step between the two materials or follow a chemical stripe. These theoretical predictions are confirmed by full numerical calculations. Generically, docking occurs for particles which tend to move away from their catalytic caps, while stripe following occurs in the opposite case. Our analysis reveals the physical mechanisms governing this behavior.

  5. Coronal mass ejections, magnetic clouds, and relativistic magnetospheric electron events: ISTP

    SciTech Connect

    Baker, D.N.; Pulkkinen, T.I.; Li, X.; Kanekal, S.G.; Blake, J.B.; Selesnick, R.S.; Henderson, M.G.; Reeves, G.D.; Spence, H.E.

    1998-08-01

    The role of high-speed solar wind streams in driving relativistic electron acceleration within the Earth{close_quote}s magnetosphere during solar activity minimum conditions has been well documented. The rising phase of the new solar activity cycle (cycle 23) commenced in 1996, and there have recently been a number of coronal mass ejections (CMEs) and related {open_quotes}magnetic clouds{close_quotes} at 1 AU. As these CME/cloud systems interact with the Earth{close_quote}s magnetosphere, some events produce substantial enhancements in the magnetospheric energetic particle population while others do not. This paper compares and contrasts relativistic electron signatures observed by the POLAR, SAMPEX, Highly Elliptical Orbit, and geostationary orbit spacecraft during two magnetic cloud events: May 27{endash}29, 1996, and January 10{endash}11, 1997. Sequences were observed in each case in which the interplanetary magnetic field was first strongly southward and then rotated northward. In both cases, there were large solar wind density enhancements toward the end of the cloud passage at 1 AU. Strong energetic electron acceleration was observed in the January event, but not in the May event. The relative geoeffectiveness for these two cases is assessed, and it is concluded that large induced electric fields ({partial_derivative}B/{partial_derivative}t) caused in situ acceleration of electrons throughout the outer radiation zone during the January 1997 event. {copyright} 1998 American Geophysical Union

  6. ELECTROSTATIC CHARGE ON NANO-PARTICLES ACTIVATES CNS MACROPHAGES (MICROGLIA).

    EPA Science Inventory

    Nanometer size particles carry free radical activity on their surface and can produce oxidative stress (OS)-mediated damage upon impact to target cells. The initiating event of phage cell activation (i.e., the oxidative burst) is unknown, although many proximal events have been i...

  7. Black hole magnetospheres

    SciTech Connect

    Nathanail, Antonios; Contopoulos, Ioannis

    2014-06-20

    We investigate the structure of the steady-state force-free magnetosphere around a Kerr black hole in various astrophysical settings. The solution Ψ(r, θ) depends on the distributions of the magnetic field line angular velocity ω(Ψ) and the poloidal electric current I(Ψ). These are obtained self-consistently as eigenfunctions that allow the solution to smoothly cross the two singular surfaces of the problem, the inner light surface inside the ergosphere, and the outer light surface, which is the generalization of the pulsar light cylinder. Magnetic field configurations that cross both singular surfaces (e.g., monopole, paraboloidal) are uniquely determined. Configurations that cross only one light surface (e.g., the artificial case of a rotating black hole embedded in a vertical magnetic field) are degenerate. We show that, similar to pulsars, black hole magnetospheres naturally develop an electric current sheet that potentially plays a very important role in the dissipation of black hole rotational energy and in the emission of high-energy radiation.

  8. The magnetosphere of Saturn

    NASA Technical Reports Server (NTRS)

    Beard, David B.; Gast, Mark A.

    1987-01-01

    Pioneer 11 and Voyager 1 and 2 magnetic field measurements over the entire flyby of Saturn's magnetic field have been analyzed by fitting a magnetospheric dipole field (i.e., a dipole field plus the field due to currents in the magnetopause), higher moments of the internal field aligned with the dipole along the rotation axis, and the field due to an equatorial sheet current to the magnetic measurements. A dipole moment of 21,431 nT R(s) exp 3, a quadrupole moment of 2403 nT R(s) exp 4, an octopole moment of 2173 nT R(s) exp 5, and an equatorial sheet current of half thickness 2.0 R(s) from about 5 R(s) to the solar edge of the magnetopause, fit the measurements over the entire magnetosphere with an rms deviation of 3.2 nT where R(s) is the planet radius, 66,330 km. The primary feature of the present analysis is the explicit inclusion of the calculated magnetopause current field, which reduces the overall rms deviation over the entire flyby from sigma values of 4.7 and 5.9 nT, using previous models, to 3.2 nT using the present.

  9. Diffusion of passive particles in active suspensions

    NASA Astrophysics Data System (ADS)

    Mussler, Matthias; Rafai, Salima; John, Thomas; Peyla, Philippe; Wagner, Christian

    2013-11-01

    We study how an active suspension consisting of a definite volume fraction of the microswimmer Chlamydomonas Reinhardtii modifies the Brownian movement of small to medium size microspheres. We present measurements and simulations of trajectories of microspheres with a diameter of 20 μm in suspensions of Chlamydomonas Reinhardtii, a so called ``puller,'' and show that the mean squared displacement of such trajectories consist of parabolic and a linear part. The linear part is due to the hydrodynamic noise of the microswimmers while the parabolic part is a consequence of directed motion events that occur randomly, when a microsphere is transported by a microswimmer on a timescale that is in higher order of magnitude than the Brownian like hydrodynamic interaction. In addition, we theoretically describe this effect with a dimensional analysis that takes the force dipole model used to describe ``puller'' like Chlamydomonas Reinhardtii into account.

  10. Energetic protons in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Mcdonald, F. B.; Schardt, A. W.; Trainor, J. H.

    1979-01-01

    The time histories, angular distributions and energy spectra of energetic protons were measured over an energy range extending from 0.2 - 20 MeV for the four passes of Pioneers 10 and 11 through the Jovian magnetosphere. Azimuthal asymmetries appear to dominate with time variations also contributing to the very complex topology. On the inbound P-10 pass the expected corotation anisotropy was not observed in the outer magnetosphere supporting the probable existence of a planetary wind in this region. Near the dawn meredian particle streaming away from the planet begins at about 15 RJ. On both the P-10 inbound and P-11 outbound passes, there are regions where only partial corotation is achieved. In the mid-magnetosphere, field-aligned streaming away from the near-equatorial current sheet region is the most prominent feature. At mid-latitudes in the subsolar regime, the streaming pattern is more chaotic and its magnitude is smaller. Qualitative discussions are presented for a number of possible mechanisms which could produce this streaming.

  11. Can Titan generate tori in Saturn's magnetosphere?

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Johnson, R. E.; Rymer, A. M.; Mitchell, D. G.

    2011-12-01

    Prior to Cassini's arrival at Saturn, nitrogen ions were thought to dominate heavy plasma in Saturn's magnetosphere and that Titan's atmosphere was the source of this nitrogen. Therefore, the presence of a Titan nitrogen torus was anticipated. However, it is now known water-group ions dominate Saturn's heavy ion plasma. While nitrogen ions have been detected beyond the orbit of Rhea, they appear to be originating from the Enceladus plumes with little nitrogen plasma detected in the magnetosphere near Titan's orbit. These results appear inconsistent with the expectation that Titan's dense relatively unprotected atmosphere should provide a significant source of heavy particles to Saturn's magnetosphere. This inconsistency suggests that the plasma environment at Titan's orbit is much more complex than originally anticipated. In this talk, we expand on our previous research that categorizes the plasma environments near Titan to include all locations along Titan's orbit. Using these categories, we develop characteristic plasma spectra of each type of environment and use these results in a 3D Monte Carlo model to more accurately examine fate of nitrogen and methane escaping Titan's atmosphere. These results are compared to Cassini observations to determine if Titan is capable of generating tori.

  12. Saturn Magnetospheric Impact on Surface Molecular Chemistry and Astrobiological Potential of Enceladus

    NASA Technical Reports Server (NTRS)

    Cooper, Paul D.; Cooper, John F.; Sittler, Edward C.; Burger, Matthew H.; Sturner, Steven J.; Rymer, Abigail M.

    2008-01-01

    The active south polar surface of Enceladus is exposed to strong chemical processing by direct interaction with charged plasma and energetic particles in the local magnetospheric environment of this icy moon. Chemical oxidation activity is suggested by detection of H202 at the surface in this region and less directly by substantial presence of C02, CO, and N2 in the plume gases. Molecular composition of the uppermost surface, including ejecta from plume activity, is radiolytically transformed mostly by penetrating energetic electrons with lesser effects from more depleted populations of energetic protons. The main sources of molecular plasma ions and E-ring dust grains in the magnetospheric environment are the cryovolcanic plume emissions from Enceladus. These molecular ions and the dust grains are chemically processed by magnetospheric interactions that further impact surface chemistry on return to Enceladus. For example, H20 neutrals dominating the emitted plume gas return to the surface mostly as H30+ ions after magnetospheric processing. Surface oxidant loading is further increased by return of radiolytically processed ice grains from the E-ring. Plume frost deposition and micrometeoroid gardening protect some fraction of newly produced molecular species from destruction by further irradiation. The evident horizontal and vertical mobility of surface ices in the south polar region drive mixing of these processed materials into the moon interior with potential impacts on deep ice molecular chemistry and plume gas production. Similarly as suggested previously for Europa, the externally driven source of radiolytic oxidants could affect evolution of life in any subsurface liquid water environments of Enceladus.

  13. Optofluidics incorporating actively controlled micro- and nano-particles

    PubMed Central

    Kayani, Aminuddin A.; Khoshmanesh, Khashayar; Ward, Stephanie A.; Mitchell, Arnan; Kalantar-zadeh, Kourosh

    2012-01-01

    The advent of optofluidic systems incorporating suspended particles has resulted in the emergence of novel applications. Such systems operate based on the fact that suspended particles can be manipulated using well-appointed active forces, and their motions, locations and local concentrations can be controlled. These forces can be exerted on both individual and clusters of particles. Having the capability to manipulate suspended particles gives users the ability for tuning the physical and, to some extent, the chemical properties of the suspension media, which addresses the needs of various advanced optofluidic systems. Additionally, the incorporation of particles results in the realization of novel optofluidic solutions used for creating optical components and sensing platforms. In this review, we present different types of active forces that are used for particle manipulations and the resulting optofluidic systems incorporating them. These systems include optical components, optofluidic detection and analysis platforms, plasmonics and Raman systems, thermal and energy related systems, and platforms specifically incorporating biological particles. We conclude the review with a discussion of future perspectives, which are expected to further advance this rapidly growing field. PMID:23864925

  14. On the occurrence of ground observations of ELF/VLF magnetospheric amplification induced by the HAARP facility

    NASA Astrophysics Data System (ADS)

    Gołkowski, M.; Cohen, M. B.; Carpenter, D. L.; Inan, U. S.

    2011-04-01

    The ionospheric heating facility of the High Frequency Active Auroral Research Program (HAARP) has been used extensively in the last 3 years for injection of ELF/VLF waves into the magnetosphere via modulated heating of the overhead auroral electrojet currents. Of particular interest are waves that are observed to be nonlinearly amplified after interaction with hot plasma electrons in the Earth's radiation belts. Past results have shown HAARP to be an effective platform for controlled studies of wave particle interactions in the Earth's magnetosphere. A summary of the experimental results is provided in the context of dependencies on geomagnetic conditions and transmitter parameters. It is deduced that the primary variable that is associated with successful ground observations of HAARP-induced magnetospheric amplification is availability of magnetospheric wave guiding structures. Such structures are found to be most prevalent under quiet geomagnetic conditions following a disturbance when the plasmapause extends to the latitude of the HAARP facility or higher. Strong electrojet currents and high amplitudes of generated ELF/VLF signals observed on the ground are poor indicators of observation probability on a day to day basis although variation of these variables can be important on minute and second timescales. Frequency-time formats with continuously increasing ELF/VLF frequency show preferential amplification as predicted by nonlinear theory of electron trapping. Amplification of signals is also found to be possible for signals with noncoherent bandwidths of up to 30 Hz.

  15. Possible evidence a Titan-generated Nitrogen Torus in Saturn's Magnetosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Rymer, A. M.; Johnson, R. E.; Lewis, G.; Coates, A. J.; Mitchell, D. G.; Young, D. T.

    2013-12-01

    Saturn's largest moon, Titan, possesses no intrinsic magnetic field which leaves its dense nitrogen-rich atmosphere relatively unprotected from direct interaction Saturn's magnetosphere. Therefore, it was logically assumed that nitrogen particles would escape from Titan's atmosphere and form a large toriodal gas cloud near Titan's orbit (in the outer magnetosphere) constituting the dominant species in the magnetosphere. Cassini observations detected nitrogen ions, however these particles exist in the inner magnetosphere and water-group particles (from Enceladus' plumes) actually dominate Saturn's heavy magnetospheric particle population. In fact, pick-up oxygen ions from Enceladus are much more abundant than nitrogen in Titan's orbit. These results appear inconsistent with the expectation that Titan's exposed atmosphere should provide a significant source of heavy particles to Saturn's magnetosphere. Resolving this inconsistency could provide import insight into atmospheric loss. Subsequent modeling and observations indicate that the observed nitrogen in the inner magnetosphere cannot be entirely produced by Enceladus. Considering these results combined with it being hard to imagine that nitrogen would not be escaping from Titan, we have continued to explore the possible presence of a nitrogen torus at Titan's orbit. In this talk, we using modeling results and observations to support a theory explaining 'torus erosion' which limits the ability to detect a Titan torus. Using these results, we also present the first detections of nitrogen in Titan's orbit possibly originating from a Titan torus. This work is supported by the NASA Cassini Data Analysis Program and NASA JPL contract 1243218 for Cassini MIMI and CAPS investigation.

  16. Magnetospheric energy principle for spherically symmetric monopolar magnetospheres.

    PubMed

    Miura, Akira

    2013-05-24

    A new magnetospheric energy principle is developed for spherically symmetric monopolar magnetospheres with open straight field lines. The principle is based on the self-adjointness of the force operator, which ensures energy conservation in the unperturbed magnetospheric plasma volume. A Neuman-type boundary condition for the perpendicular displacement at the ionosphere yields a negative contribution to the potential energy variation. This contribution makes high-mode-number incompressible field-line-bending modes unstable owing to the plasma displacement over the spherical ionospheric surface. PMID:23745887

  17. Effects of Saturn's magnetospheric dynamics on Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Edberg, N. J. T.; Andrews, D. J.; Bertucci, C.; Gurnett, D. A.; Holmberg, M. K. G.; Jackman, C. M.; Kurth, W. S.; Menietti, J. D.; Opgenoorth, H. J.; Shebanits, O.; Vigren, E.; Wahlund, J.-E.

    2015-10-01

    We use the Cassini Radio and Plasma Wave Science/Langmuir probe measurements of the electron density from the first 110 flybys of Titan to study how Saturn's magnetosphere influences Titan's ionosphere. The data is first corrected for biased sampling due to varying solar zenith angle and solar energy flux (solar cycle effects). We then present results showing that the electron density in Titan's ionosphere, in the altitude range 1600-2400 km, is increased by about a factor of 2.5 when Titan is located on the nightside of Saturn (Saturn local time (SLT) 21-03 h) compared to when on the dayside (SLT 09-15 h). For lower altitudes (1100-1600 km) the main dividing factor for the ionospheric density is the ambient magnetospheric conditions. When Titan is located in the magnetospheric current sheet, the electron density in Titan's ionosphere is about a factor of 1.4 higher compared to when Titan is located in the magnetospheric lobes. The factor of 1.4 increase in between sheet and lobe flybys is interpreted as an effect of increased particle impact ionization from ˜200 eV sheet electrons. The factor of 2.5 increase in electron density between flybys on Saturn's nightside and dayside is suggested to be an effect of the pressure balance between thermal plus magnetic pressure in Titan's ionosphere against the dynamic pressure and energetic particle pressure in Saturn's magnetosphere.

  18. Jupiter's Polar Magnetosphere: Outstanding Issues to be Addressed By Juno

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Connerney, J. E. P.; McComas, D. J.; Mauk, B.; Gladstone, R.; Adriani, A.; Bagenal, F.; Bolton, S. J.

    2014-12-01

    Juno is on course to enter polar orbit at Jupiter on July 4, 2016. After a small number of preliminary orbits during which the orbital period is reduced, approximately 30 science orbits will be executed to explore the interior of Jupiter, hence, its origin. A second primary objective of the mission, and the subject of this talk, is to carry out the first exploration of Jupiter's polar magnetosphere. All previous missions to Jupiter, including Ulysses, remained at low Jovian latitudes at close range, hence, our knowledge of Jupiter's polar magnetosphere is a composite of remote sensing (such as radio emissions in the hectometric and decametric bands as well as IR and UV images); application of observations of Earth's auroral and polar cap particles, fields, and auroral emissions; and modeling. While these likely inform our expectations of what Juno will actually measure qualitatively, Juno will provide the first in depth exploration of auroral processes at another planet, other than a small number of very brief encounters of Saturn's kilometric radio source region by Cassini. With a reasonably complete suite of in situ magnetospheric measurements coupled with remote sensing, Juno will enable us to compare Jupiter's polar magnetosphere with those expectations. Certainly, understanding the nature of auroral currents and mechanisms for particle acceleration are high on the list of priorities for these studies. In addition, it is expected that Juno will greatly improve our understanding of the mapping of auroral processes from high latitudes and low altitudes to the middle and outer magnetosphere.

  19. Evidence for magnetospheric effects on the sodium atmosphere of Mercury

    NASA Astrophysics Data System (ADS)

    Potter, A. E.; Morgan, T. H.

    1990-05-01

    Monochromatic images of Mercury at the sodium D2 emission line showed excess sodium emission in localized regions at high northern and southern latitudes and day-to-day global variations in the distribution of sodium emission. These phenomena support the suggestion that magnetospheric effects could be the cause. Sputtering of surface minerals could produce sodium vapor in polar regions during magnetic substorms, when magnetospheric ions directly impact the surface. Another important process may be the transport of sodium ions along magnetic field lines toward polar regions, where they impact directly on the surface of Mercury and are neutralized to regenerate neutral sodium atoms. Day-to-day variations in planetary sodium distributions could result from changing solar activity, which can change the magnetosphere in time scales of a few hours. Observations of the sodium exosphere may provide a tool for remote monitoring of the magnetosphere of Mercury.

  20. Discontinuous fluidization transition in dense suspensions of actively deforming particles

    NASA Astrophysics Data System (ADS)

    Tjhung, Elsen; Berthier, Ludovic

    Collective dynamics of self-propelled particles at high density have been shown to display a glass-like transition with a critical slowing down of 2 to 4 orders of magnitude. In this talk, we propose a new mechanism of injecting energy or activity via volume fluctuations. We show that the behaviour of actively deforming particles is strikingly different from that of self-propelled particles. In particular, we find a discontinuous non-equilibrium phase transition from a flowing state to an arrested state. Our minimal model might also explain the collective dynamics in epithelial tissues. In particular, without needing self-propulsion or cell-cell adhesion, volume fluctuations of individual cells alone might be sufficient to give rise to an active fluidization and collective dynamics in densely packed tissues.

  1. Nightside magnetospheric current circuit: Time constants of the solar wind-magnetosphere coupling

    NASA Astrophysics Data System (ADS)

    Ohtani, S.; Uozumi, T.

    2014-05-01

    This study addresses the characteristics of the nightside magnetospheric current system using the analogy of an electric circuit. The modeled circuit consists of the generator (V: solar wind), inductor (L: tail lobes), capacitor (C: plasma sheet convection), and resistor (R: particle energization). The electric circuit has three time constants: τCR(=CR), τLC(=√LC), and τL/R(=L/R). Here τCR is of the order of the ion gyroperiod in the plasma sheet, τLC is a global timescale (2πτLC is several tens of minutes), and τL/R is even longer (several hours). Despite uncertainty in the estimate of each circuit element, τCR ≪ τLC ≪ τL/R holds generally for the magnetosphere, which characterizes the electric circuit as overdamped. The following implications are obtained: (1) During the substorm growth phase the cross-tail current increases continuously even if interplanetary magnetic field (IMF) BZ does not change after southward turning; (2) the magnetotail current weakens following northward turnings if the change of IMF BZ is comparable to the preceding southward IMF BZ; otherwise it may strengthen continuously if more gradually; (3) during the early main phase of magnetospheric storms the enhancement of the lobe magnetic energy is far more prominent than the enhancements of the kinematic and kinetic energies of the plasma sheet plasma; (4) The efficiency of the solar wind-magnetosphere coupling changes on a timescale of several hours (τL/R) through the change of the tail flaring, and so does the cross polar-cap potential; and (5) the magnetospheric current system does not resonate to an oscillatory external driver, and therefore, the periodicity of some magnetotail phenomena reflects that of their triggers.

  2. Quiet time particle fluxes and active phenomena on the Sun

    NASA Astrophysics Data System (ADS)

    Ishkov, Vitaly; Zeldovich, Mariya; Logachev, Yurii; Kecskemety, Karoly

    Using ACE, SOHO and STEREO data the connection of quiet time particle fluxes with active processes on the Sun is examined in the 23rd SC. Investigation of the intervals selected in the conditions of low solar activity supports our assumption that the active structures on the Sun arising during minimum solar activity are mostly responsible for background particle fluxes. Sources on the Sun of charged particles with energies 0.3-8 MeV/nucleon have been determined during quiet time periods over all solar cycle by comparison with solar wind fluxes. It is shown that at the solar maximum a part of background fluxes with abundances of C and Fe corresponding to mean values in solar corona resulted from equatorial coronal holes. Bipolar structures arising in the hole area (bright X-ray points) were accompanied in most cases by the ejection of solar plasma according to HINOTORI satellite. The speed of a part of such emissions and open magnetic field lines above coronal holes can allow energetic particles to escape into the interplanetary space. During solar minimum abundances of C and Fe in majority of quiet time fluxes corresponded to solar wind values possibly indicating the common origin of energetic particle and solar wind fluxes.

  3. Physisorption of enzymatically active chymotrypsin on titania colloidal particles.

    PubMed

    Derr, Ludmilla; Dringen, Ralf; Treccani, Laura; Hildebrand, Nils; Ciacchi, Lucio Colombi; Rezwan, Kurosch

    2015-10-01

    In this study we use a straightforward experimental method to probe the presence and activity of the proteolytic enzyme α-chymotrypsin adsorbed on titania colloidal particles. We show that the adsorption of α-chymotrypsin on the particles is irreversible and pH-dependent. At pH 8 the amount of adsorbed chymotrypsin is threefold higher compared to the adsorption at pH 5. However, we observe that the adsorption is accompanied by a substantial loss of enzymatic activity, and only around 6-9% of the initial enzyme activity is retained. A Michaelis-Menten kinetics analysis of both unbound and TiO2-bound chymotrypsin shows that the K(M) value is increased from ∼10 μM for free chymotrypsin to ∼40 μM for the particle bound enzyme. Such activity decrease could be related by the hindered accessibility of substrate to the active site of adsorbed chymotrypsin, or by adsorption-induced structural changes. Our simple experimental method does not require any complex technical equipment, can be applied to a broad range of hydrolytic enzymes and to various types of colloidal materials. Our approach allows an easy, fast and reliable determination of particle surface-bound enzyme activity and has high potential for development of future enzyme-based biotechnological and industrial processes. PMID:26072448

  4. Naphthalene SOA: redox activity and naphthoquinone gas-particle partitioning

    NASA Astrophysics Data System (ADS)

    McWhinney, R. D.; Zhou, S.; Abbatt, J. P. D.

    2013-10-01

    Chamber secondary organic aerosol (SOA) from low-NOx photooxidation of naphthalene by hydroxyl radical was examined with respect to its redox cycling behaviour using the dithiothreitol (DTT) assay. Naphthalene SOA was highly redox-active, consuming DTT at an average rate of 118 ± 14 pmol per minute per μg of SOA material. Measured particle-phase masses of the major previously identified redox active products, 1,2- and 1,4-naphthoquinone, accounted for only 21 ± 3% of the observed redox cycling activity. The redox-active 5-hydroxy-1,4-naphthoquinone was identified as a new minor product of naphthalene oxidation, and including this species in redox activity predictions increased the predicted DTT reactivity to 30 ± 5% of observations. These results suggest that there are substantial unidentified redox-active SOA constituents beyond the small quinones that may be important toxic components of these particles. A gas-to-SOA particle partitioning coefficient was calculated to be (7.0 ± 2.5) × 10-4 m3 μg-1 for 1,4-naphthoquinone at 25 °C. This value suggests that under typical warm conditions, 1,4-naphthoquinone is unlikely to contribute strongly to redox behaviour of ambient particles, although further work is needed to determine the potential impact under conditions such as low temperatures where partitioning to the particle is more favourable. Also, higher order oxidation products that likely account for a substantial fraction of the redox cycling capability of the naphthalene SOA are likely to partition much more strongly to the particle phase.

  5. The magnetospheres of the outer planets

    SciTech Connect

    Mcnutt, R.L., Jr. )

    1991-01-01

    Research on the magnetospheres of all of the outer planets including Jupiter, Uranus, Neptune, and Pluto is reviewed for the 1987-1990 time period. Particular attention is given to magnetospheric structure, plasma transport, Jovian aurora, Io and the plasma torus, Titan and its magnetospheric interactions, rings and dusty plasmas, magnetospheric convection, and satellite interactions.

  6. Latitudinal profiles of solar protons in the Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Lazutin, L.

    2016-02-01

    Dynamics of the latitudinal profiles penetrating into magnetosphere solar protons is studied using particle spectrometers data on board of the low latitude satellite CORONAS-F with orbit inclination ∼83o. Formations of several different types of the profiles during magnetic storms are considered.

  7. A study of atmosphere-ionosphere-magnetosphere coupling

    NASA Technical Reports Server (NTRS)

    Raitt, W. J.; Paris, J. L.

    1982-01-01

    The properties of low energy plasma in the magnetosphere were predicted. The effects of wave particle interactions involving the concept of plasmons are studied, and quantum mechanical formulations are used for the processes occurring and bulk energization of the low energy plasma are investigated through the concept of the energy momentum tensor for the plasma and its electromagnetic environment.

  8. Temporal variation of the oxygen flux in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Beaujean, R.

    1995-01-01

    The intensity of oxygen ions in the inner magnetosphere was studied by several experiments using track detectors. This report combines the measurements on Soviet COSMOS satellites of the period 1985-1988 with earlier results from the SL-1 mission (1983). The evident temporal variation supports the conclusion that the orgin for these particles is trapping of the anomalous component.

  9. The Magnetospheric Multiscale Constellation

    NASA Astrophysics Data System (ADS)

    Tooley, C. R.; Black, R. K.; Robertson, B. P.; Stone, J. M.; Pope, S. E.; Davis, G. T.

    2016-03-01

    The Magnetospheric Multiscale (MMS) mission is the fourth mission of the Solar Terrestrial Probe (STP) program of the National Aeronautics and Space Administration (NASA). The MMS mission was launched on March 12, 2015. The MMS mission consists of four identically instrumented spin-stabilized observatories which are flown in formation to perform the first definitive study of magnetic reconnection in space. The MMS mission was presented with numerous technical challenges, including the simultaneous construction and launch of four identical large spacecraft with 100 instruments total, stringent electromagnetic cleanliness requirements, closed-loop precision maneuvering and pointing of spinning flexible spacecraft, on-board GPS based orbit determination far above the GPS constellation, and a flight dynamics design that enables formation flying with separation distances as small as 10 km. This paper describes the overall mission design and presents an overview of the design, testing, and early on-orbit operation of the spacecraft systems and instrument suite.

  10. Magnetospheric Plasma Physics

    NASA Astrophysics Data System (ADS)

    Mauk, Barry H.

    Magnetospheric Plasma Physics is volume 4 of an ongoing series of review books entitled Developments in Earth and Planetary Sciences organized by the Center for Academic Publications Japan. The series is intended to stress Japanese work; however, the present volume was written by seven internationally selected authors who have reviewed works from a broad range of sources. This volume is composed of articles drawn from five lecture series presented at the Autumn College o f Plasma Physics, International Center for Theoretical Physics, Trieste, Italy, October-November 1979. The audiences for these lecture series were plasma and/or space plasma physicists, or students of the same, and the level and tone of this volume clearly reflect that condition.

  11. The Extended Pulsar Magnetosphere

    NASA Technical Reports Server (NTRS)

    Constantinos, Kalapotharakos; Demosthenes, Kazanas; Ioannis, Contopoulos

    2012-01-01

    We present the structure of the 3D ideal MHD pulsar magnetosphere to a radius ten times that of the light cylinder, a distance about an order of magnitude larger than any previous such numerical treatment. Its overall structure exhibits a stable, smooth, well-defined undulating current sheet which approaches the kinematic split monopole solution of Bogovalov 1999 only after a careful introduction of diffusivity even in the highest resolution simulations. It also exhibits an intriguing spiral region at the crossing of two zero charge surfaces on the current sheet, which shows a destabilizing behavior more prominent in higher resolution simulations. We discuss the possibility that this region is physically (and not numerically) unstable. Finally, we present the spiral pulsar antenna radiation pattern.

  12. Kinetics of small particle activation in supersaturated vapors

    SciTech Connect

    McGraw, R.; Wang, J.

    2010-08-29

    We examine the nucleated (with barrier) activation of perfectly wetting (zero contact angle) particles ranging from bulk size down to one nanometer. Thermodynamic properties of the particles, coated with liquid layers of varying thickness and surrounded by vapor, are analyzed. Nano-size particles are predicted to activate at relative humidity below the Kelvin curve on crossing a nucleation barrier, located at a critical liquid layer thickness such that the total particle size (core + liquid layer) equals the Kelvin radius (Fig. 1). This barrier vanishes precisely as the critical layer thickness approaches the thin layer limit and the Kelvin radius equals the radius of the particle itself. These considerations are similar to those included in Fletcher's theory (Fletcher, 1958) however the present analysis differs in several important respects. Firstly, where Fletcher used the classical prefactor-exponent form for the nucleation rate, requiring separate estimation of the kinetic prefactor, we solve a diffusion-drift equation that is equivalent to including the full Becker-Doering (BD) multi-state kinetics of condensation/evaporation along the growth coordinate. We also determine the mean first passage time (MFPT) for barrier crossing (Wedekind et al., 2007), which is shown to provide a generalization of BD nucleation kinetics especially useful for barrier heights that are considerably lower than those typically encountered in homogeneous vapor-liquid nucleation, and make explicit comparisons between the MFPT and BD kinetic models. Barrier heights for heterogeneous nucleation are computed by a thermo-dynamic area construction introduced recently to model deliquescence and efflorescence of small particles (McGraw and Lewis, 2009). In addition to providing a graphical representation of the activation process that offers new insights, the area construction provides a molecular approach that avoids explicit use of the interfacial tension. Typical barrier profiles for

  13. Joule Heating as a Signature of Magnetosphere-Ionosphere-Thermosphere Coupling

    NASA Astrophysics Data System (ADS)

    Ceren Kalafatoglu Eyiguler, Emine; Kaymaz, Zerefsan

    2016-07-01

    Since its first proposal by Birkeland in the early 1900s, the link between magnetosphere and ionosphere (M-I) has been immensely studied but there are still great variety of unsolved problems ranging from how to correctly balance the field aligned current (FAC) closure in the ionosphere to the resulting interactions between ions and neutrals in the ionosphere, and how the ionospheric conductivity and neutral wind control the M-I feedback to the mapping of the ionospheric regions to the magnetotail. It is now well known that during magnetically disturbed periods, the energy deposited to the magnetosphere by the solar wind is partitioned mainly between three domains: the ring current, ionosphere (via auroral particle precipitation and Joule heating) and the plasmoid release in the magnetotail. It is previously found that large part of this transferred energy is in the form of Joule heating which is the increase in ion-neutral collisions due to the increased energy input. However, Joule heating is also affected by the enhanced neutral wind motion during geomagnetic storms and substorms. Thus, it is one of the key manifestations of the M-I-T coupling. In this talk, we first give a through review of the present studies and recent advancements in the M-I-T research area then show the link between the magnetosphere and ionosphere by investigating the activity-time Joule heating variations as well as paying special attention to the neutral wind effects on Joule heating.

  14. Interaction forces between waterborne bacteria and activated carbon particles.

    PubMed

    Busscher, Henk J; Dijkstra, Rene J B; Langworthy, Don E; Collias, Dimitris I; Bjorkquist, David W; Mitchell, Michael D; Van der Mei, Henny C

    2008-06-01

    Activated carbons remove waterborne bacteria from potable water systems through attractive Lifshitz-van der Waals forces despite electrostatic repulsion between negatively charged cells and carbon surfaces. In this paper we quantify the interaction forces between bacteria with negatively and positively charged, mesoporous wood-based carbons, as well as with a microporous coconut carbon. To this end, we glued carbon particles to the cantilever of an atomic force microscope and measured the interaction forces upon approach and retraction of thus made tips. Waterborne Raoultella terrigena and Escherichia coli adhered weakly (1-2 nN) to different activated carbon particles, and the main difference between the activated carbons was the percentage of curves with attractive sites revealed upon traversing of a carbon particle through the bacterial EPS layer. The percentage of curves showing adhesion forces upon retraction varied between 21% and 69%, and was highest for R. terrigena with positively charged carbon (66%) and a coconut carbon (69%). Macroscopic bacterial removal by the mesoporous carbon particles increased with increasing percentages of attractive sites revealed upon traversing a carbon particle through the outer bacterial surface layer. PMID:18405910

  15. Brownian aggregation rate of colloid particles with several active sites

    SciTech Connect

    Nekrasov, Vyacheslav M.; Yurkin, Maxim A.; Chernyshev, Andrei V.; Polshchitsin, Alexey A.; Yakovleva, Galina E.; Maltsev, Valeri P.

    2014-08-14

    We theoretically analyze the aggregation kinetics of colloid particles with several active sites. Such particles (so-called “patchy particles”) are well known as chemically anisotropic reactants, but the corresponding rate constant of their aggregation has not yet been established in a convenient analytical form. Using kinematic approximation for the diffusion problem, we derived an analytical formula for the diffusion-controlled reaction rate constant between two colloid particles (or clusters) with several small active sites under the following assumptions: the relative translational motion is Brownian diffusion, and the isotropic stochastic reorientation of each particle is Markovian and arbitrarily correlated. This formula was shown to produce accurate results in comparison with more sophisticated approaches. Also, to account for the case of a low number of active sites per particle we used Monte Carlo stochastic algorithm based on Gillespie method. Simulations showed that such discrete model is required when this number is less than 10. Finally, we applied the developed approach to the simulation of immunoagglutination, assuming that the formed clusters have fractal structure.

  16. On plasma convection in Saturn's magnetosphere

    NASA Astrophysics Data System (ADS)

    Livi, Roberto

    We use CAPS plasma data to derive particle characteristics within Saturn's inner magnetosphere. Our approach is to first develop a forward-modeling program to derive 1-dimensional (1D) isotropic plasma characteristics in Saturn's inner, equatorial magnetosphere using a novel correction for the spacecraft potential and penetrating background radiation. The advantage of this fitting routine is the simultaneous modeling of plasma data and systematic errors when operating on large data sets, which greatly reduces the computation time and accurately quantifies instrument noise. The data set consists of particle measurements from the Electron Spectrometer (ELS) and the Ion Mass Spectrometer (IMS), which are part of the Cassini Plasma Spectrometer (CAPS) instrument suite onboard the Cassini spacecraft. The data is limited to peak ion flux measurements within +/-10° magnetic latitude and 3-15 geocentric equatorial radial distance (RS). Systematic errors such as spacecraft charging and penetrating background radiation are parametrized individually in the modeling and are automatically addressed during the fitting procedure. The resulting values are in turn used as cross-calibration between IMS and ELS, where we show a significant improvement in magnetospheric electron densities and minor changes in the ion characteristics due to the error adjustments. Preliminary results show ion and electron densities in close agreement, consistent with charge neutrality throughout Saturn's inner magnetosphere and confirming the spacecraft potential to be a common influence on IMS and ELS. Comparison of derived plasma parameters with results from previous studies using CAPS data and the Radio And Plasma Wave Science (RPWS) investigation yields good agreement. Using the derived plasma characteristics we focus on the radial transport of hot electrons. We present evidence of loss-free adiabatic transport of equatorially mirroring electrons (100 eV - 10 keV) in Saturn's magnetosphere between

  17. Observations of large transient magnetospheric electric fields

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Heppner, J. P.

    1977-01-01

    Transient electric field events were observed with the long, double probe instrumentation carried by the IMP-6 satellite. Nine, clearly defined, exceptionally large amplitude events are presented here. The events are observed in the midnight sector at geocentric distances 3.5 to .5.5 R sub e at middle latitudes within a magnetic L-shell range of 4.8 to 7.5. They usually have a total duration of one to several minutes, with peak power spectra amplitudes occurring at a frequency of about 0.3 Hz. The events occur under magnetically disturbed conditions, and in most cases they can be associated with negative dH/dt excursions at magnetic observatories located near the foot of the magnetic field line intersecting IMP-6. The magnetospheric motions calculated for these electric fields indicated a quasi-stochastical diffusive process rather than the general inward magnetospheric collapsing motion expected during the expansive phases of auroral substorm activity.

  18. Axisymmetric, Nonstationary Black Hole Magnetospheres: Revisited

    NASA Astrophysics Data System (ADS)

    Song, Yoo Geun; Park, Seok Jae

    2015-10-01

    An axisymmetric, stationary, general-relativistic, electrodynamic engine model of an active galactic nucleus was formulated by Macdonald and Thorne that consisted of a supermassive black hole surrounded by a plasma magnetosphere and a magnetized accretion disk. Based on this initial formulation, a nonstationary, force-free version of their model was constructed by Park & Vishniac (PV), with the simplifying assumption that the poloidal component of the magnetic field line velocity be confined along the radial direction in cylindrical polar coordinates. In this paper, we derive the new, nonstationary “Transfield Equation,” which was not specified in PV. If we can solve this “Transfield Equation” numerically, then we will understand the axisymmetric, nonstationary black hole magnetosphere in more rigorous ways.

  19. Mercury's magnetosphere after MESSENGER's first flyby.

    PubMed

    Slavin, James A; Acuña, Mario H; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Gloeckler, George; Gold, Robert E; Ho, George C; Killen, Rosemary M; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Nittler, Larry R; Raines, Jim M; Schriver, David; Solomon, Sean C; Starr, Richard D; Trávnícek, Pavel; Zurbuchen, Thomas H

    2008-07-01

    Observations by MESSENGER show that Mercury's magnetosphere is immersed in a comet-like cloud of planetary ions. The most abundant, Na+, is broadly distributed but exhibits flux maxima in the magnetosheath, where the local plasma flow speed is high, and near the spacecraft's closest approach, where atmospheric density should peak. The magnetic field showed reconnection signatures in the form of flux transfer events, azimuthal rotations consistent with Kelvin-Helmholtz waves along the magnetopause, and extensive ultralow-frequency wave activity. Two outbound current sheet boundaries were observed, across which the magnetic field decreased in a manner suggestive of a double magnetopause. The separation of these current layers, comparable to the gyro-radius of a Na+ pickup ion entering the magnetosphere after being accelerated in the magnetosheath, may indicate a planetary ion boundary layer. PMID:18599776

  20. Active Brownian Particles. From Individual to Collective Stochastic Dynamics

    NASA Astrophysics Data System (ADS)

    Romanczuk, P.; Bär, M.; Ebeling, W.; Lindner, B.; Schimansky-Geier, L.

    2012-03-01

    We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.

  1. Micrometeoroid impact on planetary satellites as a magnetospheric mass source

    NASA Technical Reports Server (NTRS)

    Haff, P. K.; Eviatar, A.

    1986-01-01

    Proceeding from the observation that planetary satellites are important sources of mass for planetary magnetospheres, it is noted that meteoroid impact vaporization may compete with charged particle sputtering as a supply mechanism. After considering meteoroid-driven vapor sources in the Jovian and Kronian systems, it is concluded that while the larger impact flux values obtained for the outer solar system suggest a role for impact vaporization in the cases of both Jupiter and Saturn, this process will not predominate over sputtering; at the lower end of the impact flux range, however, sputtering everywhere dominates magnetospheric mass loading.

  2. Functionally charged nanosize particles differentially activate BV2 microglia.

    EPA Science Inventory

    The effect of particle surface charge on the biological activation of immortalized mouse microglia (BV2) was examined. Nanosize (860-950 nm) spherical polystyrene microparticles (SPM) were coated with carboxyl (COOH-) or dimethyl amino (CH3)2-N- groups to give a net negative or p...

  3. Moon-magnetosphere interactions in the Jupiter and Saturn systems

    NASA Astrophysics Data System (ADS)

    Jones, G. H.

    2013-05-01

    Most of the larger moons of the giant planets Jupiter and Saturn are continuously immersed in their parent planets' extensive magnetospheres. Because of this, these tidally-locked bodies are permanently exposed to magnetospheric plasma. An overview is given of the many modes of interaction between the magnetospheres and moons. The largest moon, Ganymede, possesses its own magnetic field that forms a miniature magnetosphere within the Jovian magnetosphere. Saturn's largest moon, Titan, with its extensive atmosphere, has a unique interaction with the plasma, which plays a key role in the complex chemical reactions occurring in its ionosphere and at lower altitudes. We review key processes occurring at other moons, such as the production of sputter-induced exospheres, surface charging processes, and the electrodynamic induction that has revealed so much about the Galilean moons' interior structures. There are key parallels, and differences, between the active moons Io and Enceladus, and the roles that they play in their respective planets' magnetospheres. We close with a summary of some key questions that remain to be answered by the Cassini-Huygens mission at Saturn, and those to be addressed by future missions to the Jovian system.

  4. Ion Trajectories In Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Killen, R.

    The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere obtained by the Toffoletto- Hill (JGR 98, 1339, 1993) model of an open magnetosphere, and supplement it with the Ding et al. (Phys. Space Plasmas, 1996) potential solver to represent the convection electric field. We calculate the fractional escape rate of sodium, potassium and argon ions as a function of the interplanetary magnetic field (IMF) direction and magnitude.

  5. Ice nucleus activity measurements of solid rocket motor exhaust particles

    NASA Technical Reports Server (NTRS)

    Keller, V. W. (Compiler)

    1986-01-01

    The ice Nucleus activity of exhaust particles generated from combustion of Space Shuttle propellant in small rocket motors has been measured. The activity at -20 C was substantially lower than that of aerosols generated by unpressurized combustion of propellant samples in previous studies. The activity decays rapidly with time and is decreased further in the presence of moist air. These tests corroborate the low effectivity ice nucleus measurement results obtained in the exhaust ground cloud of the Space Shuttle. Such low ice nucleus activity implies that Space Shuttle induced inadvertent weather modification via an ice phase process is extremely unlikely.

  6. The Magnetosphere of Ganymede (Invited)

    NASA Astrophysics Data System (ADS)

    Kivelson, M.

    2013-12-01

    Before the 1980s who would have guessed that Jupiter's moon Ganymede was destined to become an exemplar of extremes? Titan had long been described as the largest moon in the solar system with a radius > 2800 km [e.g., Smith, 1980]. Only after Voyager 1 measured the scale of its atmosphere did Titan (radius 2575 km) cede its place as the largest moon in the solar system to Ganymede (radius 2634.1 km). Thereafter Galileo's flybys established additional extraordinary properties of Ganymede. It is the only moon with an intrinsic magnetic field, the only body in the solar system whose magnetosphere forms in a sub-Alfvénic flow, and the only body that does not rotate relative to the symmetry axis of its magnetosphere. Its magnetospheric structure is of special interest as a prototype for magnetospheres in a parameter regime not found in the solar wind. Our knowledge of its properties is based on a combination of in situ and remote sensing measurements, somewhat sketchy but most informative, supplemented by results from computer simulations. To some extent Ganymede's magnetosphere is remarkable for what it lacks. It has no bow shock, no radiation belts, and no plasmasphere. Its shape is also unique, with Alfvén wings stretched almost transverse to the upstream flow replacing tail lobes folded back in the flow direction. It is the only magnetosphere embedded within a magnetosphere, a situation that implies highly predictable and slowly changing upstream plasma and field conditions. This predictability has enabled us to characterize the properties of reconnection under known, steady upstream conditions. Ganymede's magnetosphere becomes even more interesting when compared with other planetary magnetospheres. Using Mach numbers to order magnetospheres from Ganymede to the gas giants, we learn a great deal about the physics relevant to such systems. Even the heliosphere can be fit into the picture. The IBEX spacecraft [McComas et al., 2009] measures the spatial distribution

  7. Bacteria associated with granular activated carbon particles in drinking water.

    PubMed Central

    Camper, A K; LeChevallier, M W; Broadaway, S C; McFeters, G A

    1986-01-01

    A sampling protocol was developed to examine particles released from granular activated carbon filter beds. A gauze filter/Swinnex procedure was used to collect carbon fines from 201 granular activated carbon-treated drinking water samples over 12 months. Application of a homogenization procedure (developed previously) indicated that 41.4% of the water samples had heterotrophic plate count bacteria attached to carbon particles. With the enumeration procedures described, heterotrophic plate count bacteria were recovered at an average rate of 8.6 times higher than by conventional analyses. Over 17% of the samples contained carbon particles colonized with coliform bacteria as enumerated with modified most-probable-number and membrane filter techniques. In some instances coliform recoveries were 122 to 1,194 times higher than by standard procedures. Nearly 28% of the coliforms attached to these particles in drinking water exhibited the fecal biotype. Scanning electron micrographs of carbon fines from treated drinking water showed microcolonies of bacteria on particle surfaces. These data indicate that bacteria attached to carbon fines may be an important mechanism by which microorganisms penetrate treatment barriers and enter potable water supplies. PMID:3767356

  8. Electric fields in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

    Two techniques, tracking the motions of Ba(+) clouds and measuring the differences in floating potential between symmetric double probes, were successful in: (1) demonstrating the basic convective nature of magnetospheric electric fields, (2) mapping global patterns of convection at upper ionosphere levels, and (3) revealing the physics of electric currents in the ionosphere and the importance of magnetosphere-ionosphere feedback in altering the imposed convection.

  9. Global and Multi-scale Dynamics of the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Sharma, A. S.; Sitnov, M. I.

    2001-05-01

    Earth's magnetosphere during substorms demonstrates a number of characteristic features such as low effective dimension, hysteresis and power-law spectra of fluctuations on different scales. The dynamics, on the largest scale, associated with substorms, are in reasonable agreement with low-dimensional magnetospheric models and in particular those of inverse bifurcations. However, deviations from the low-dimensional picture are not negligible, making the nonequilibrium phase transition more appropriate as a dynamical analogue of the substorm activity. On the other hand, the multi- scale magnetospheric dynamics cannot be restricted to the self-organized criticality (SOC), which is based on a class of mathematical analogues of sandpiles. Like real sandpiles the magnetosphere demonstrates during substorms the features, which are distinct from SOC and more reminiscent again to conventional phase transitions. While the multi-scale substorm activity resembles second-order phase transitions, the largest substorm avalanches are shown to reveal the features of first-order nonequilibrium transitions including hysteresis phenomenon and global structure of the type of the "temperature-pressure-density" diagram. Moreover, this diagram allows one to compute a critical exponent, consistent with the second-order phase transitions, and reflects the multiscale aspect of the substorm activity, different from power-law frequency and scale spectra of autonomous systems. In contrast to SOC exponents, the exponent relates input and output parameters of the magnetosphere. Using an analogy with the dynamical Ising model in the mean-field approximation we show the connection between this data-derived exponent of nonequilibrium transitions in the magnetosphere and the standard critical exponent β of equilibrium second-order phase transitions. We discuss also further developments of the phase tarnsition approach to modeling magnetospheric activity using the multifractal, mutual information

  10. High Energy Emission from Pulsar Magnetospheres and Winds

    NASA Astrophysics Data System (ADS)

    Spitkovsky, Anatoly

    Recent gamma-ray observations of pulsars and their nebulae suggest an important role played by magnetic reconnection in determining the structure of the magnetosphere and the wind and in the acceleration of particles that lead to the high energy emission. Strong current sheets that are susceptible to magnetic dissipation are found near the light cylinder of the pulsar and persist throughout the wind. This proposal investigates the processes that occur in these current sheets, and determines their structure and particle acceleration properties. A suite of relativistic MHD and particle-in-cell kinetic simulations will be used to obtain the global 3D geometry of the magnetosphere, flow geometry in the current sheet, and calculate the dissipation of the current both near the pulsar and in the termination shock of the pulsar wind. The results will be applied to modeling the beaming in pulsar gamma-ray light curves, and to understanding particle acceleration in broadband and flaring nebular emission.

  11. The influence of hydroxyapatite particles on osteoclast cell activities.

    PubMed

    Sun, J S; Lin, F H; Hung, T Y; Tsuang, Y H; Chang, W H; Liu, H C

    1999-06-15

    Aseptic loosening after total joint arthroplasty is a major problem in orthopedic surgery. Small particles from material wear have been reported as the main cause of implant failure. For this reason, investigation into possible wear particles from the materials used in the implant may lead to longevity after arthroplasty. Hydroxyapatite (HA) has been extensively investigated and reported as an excellent biomaterial with excellent biocompatibility. In this study, we used an in vitro osteoblast/osteoclast model to test the biocompatibility of various-sized HA particles. Primary osteoclasts/osteoblasts were co-cultured with different-sized HA particles (0.5-3.0 microm, 37-53 microm, 177-205 microm, and 420-841 microm) for 3 h, 1 day, 3 days, and 7 days. Cellular responses to the HA particles were evaluated by changes in cell counts and the secretion of transforming growth factor (TGF-beta1), alkaline phosphatase (ALP), tumor necrosis factor (TNF-alpha), prostaglandin (PGE2), and lactate dehydrogenase (LDH) in the supernatant of the culture media. The results showed that osteoblasts/osteoclasts co-cultured with HA particles smaller than 53 microm undergo the most significant changes. Cellular counts significantly decreased, and the changes were more obvious in the osteoblast population. There also was a significant decrease in TGF-beta1 concentration and a significant increase in PGE2 and LDH concentration, but there were no changes in the TNF-alpha or ALP titer. It can be concluded that larger HA particles may be quite compatible with bone cells while smaller-sized HA particles can both activate the osteoclasts and decrease the cell population of the osteoblasts. Justification for the additional expense incurred with the use of hydroxyapatite in primary total hip arthroplasty should be further evaluated. PMID:10321703

  12. Overview of Results from the Cassini Magnetospheric Imaging Instrument (MIMI) During the First Year of Operations

    NASA Technical Reports Server (NTRS)

    Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.; Livi, S.; Roelof, E. C.; Dandouras, J.; Mauk, B. H.; Brandt, J. P.; Paranicas, C.

    2005-01-01

    The MIMI investigation comprises three sensors covering the indicated energy ranges: the Ion and Neutral Camera (INCA) -- 7 keV/nuc Magnetospheric Measurement System (LEMMS) 0.02 3 Mev) and protons (1.6 < E < 160 Mev) from the back end of the dual field-of-view telescope. The Saturn observation sequences began in January, 2004 and culminated in Saturn Orbit Insertion on July 1, 2004. The MIMI sensors observed substantial activity in interplanetary space for several months prior to SOI, including several interplanetary shocks associated with corotating interaction regions, numerous increases most likely originating from particle streams in the vicinity of the Saturnian bow shock and energetic neutral atoms (ENA) emanating from Saturn s magnetosphere. Results following SOI revealed: a dynamical magnetosphere with a day-night asymmetry and an 11-hour periodicity; several water-product ions (O+, OH+, H2O+), but little N+; inferred quantities of neutral gas sufficient to cause major losses in the trapped ions and electrons in the middle and inner magnetosphere; a Titan exosphere that is a copious source of ENA; INCA imaging through ENA has also revealed a previously unknown radiation belt residing inward of the D-ring that is most likely the result of double charge-exchange between the main radiation belt and the upper layers of Saturn s exosphere. Finally, there is ample evidence for the presence of substorm-like injections of plasma that subsequently corotates for a number of days before dissipating on the night-side magnetotail. The observations will be presented and discussed in the context of current theoretical models.

  13. Identification of Ice Nucleation Active Sites on Silicate Dust Particles

    NASA Astrophysics Data System (ADS)

    Zolles, Tobias; Burkart, Julia; Häusler, Thomas; Pummer, Bernhard; Hitzenberger, Regina; Grothe, Hinrich

    2015-04-01

    Mineral dusts originating from Earth's crust are known to be important atmospheric ice nuclei. In agreement with earlier studies, feldspar was found as the most active of the tested natural mineral dusts [1-3]. Nevertheless, among those structures K-feldspar showed by far the highest ice nucleation activity. In this study, the reasons for its activity and the difference in the activity of the different feldspars were investigated in closer details. Conclusions are drawn from scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy, and oil-immersion freezing experiments. We give a potential explanation of the increased ice nucleation activity of K-feldspar. The ice nucleating sites are very much dependent on the alkali ion present by altering the water structure and the feldspar surface. The higher activity of K-feldspar can be attributed to the presence of potassium ions on the surface and surface bilayer. The alkali-ions have different hydration shells and thus an influence on the ice nucleation activity of feldspar. Chaotropic behavior of Calcium and Sodium ions are lowering the ice nucleation potential of the other feldspars, while kosmotropic Potassium has a neutral or even positive effect. Furthermore we investigated the influence of milling onto the ice nucleation of quartz particles. The ice nucleation activity can be increased by mechanical milling, by introducing more molecular, nucleation active defects to the particle surface. This effect is larger than expected by plane surface increase. [1] Atkinson et al. The Importance of Feldspar for Ice Nucleation by Mineral Dust in Mixed-Phase Clouds. Nature 2013, 498, 355-358. [2] Yakobi-Hancock et al.. Feldspar Minerals as Efficient Deposition Ice Nuclei. Atmos. Chem. Phys. 2013, 13, 11175-11185. [3] Zolles et al. Identification of Ice Nucleation Active Sites on Feldspar Dust Particles. J. Phys. Chem. A 2015 accepted.

  14. Magnetospheric Multiscale Overview and Science Objectives

    NASA Astrophysics Data System (ADS)

    Burch, J. L.; Moore, T. E.; Torbert, R. B.; Giles, B. L.

    2016-03-01

    Magnetospheric Multiscale (MMS), a NASA four-spacecraft constellation mission launched on March 12, 2015, will investigate magnetic reconnection in the boundary regions of the Earth's magnetosphere, particularly along its dayside boundary with the solar wind and the neutral sheet in the magnetic tail. The most important goal of MMS is to conduct a definitive experiment to determine what causes magnetic field lines to reconnect in a collisionless plasma. The significance of the MMS results will extend far beyond the Earth's magnetosphere because reconnection is known to occur in interplanetary space and in the solar corona where it is responsible for solar flares and the disconnection events known as coronal mass ejections. Active research is also being conducted on reconnection in the laboratory and specifically in magnetic-confinement fusion devices in which it is a limiting factor in achieving and maintaining electron temperatures high enough to initiate fusion. Finally, reconnection is proposed as the cause of numerous phenomena throughout the universe such as comet-tail disconnection events, magnetar flares, supernova ejections, and dynamics of neutron-star accretion disks. The MMS mission design is focused on answering specific questions about reconnection at the Earth's magnetosphere. The prime focus of the mission is on determining the kinetic processes occurring in the electron diffusion region that are responsible for reconnection and that determine how it is initiated; but the mission will also place that physics into the context of the broad spectrum of physical processes associated with reconnection. Connections to other disciplines such as solar physics, astrophysics, and laboratory plasma physics are expected to be made through theory and modeling as informed by the MMS results.

  15. Solar wind-magnetosphere energy input functions

    SciTech Connect

    Bargatze, L.F.; McPherron, R.L.; Baker, D.N.

    1985-01-01

    A new formula for the solar wind-magnetosphere energy input parameter, P/sub i/, is sought by applying the constraints imposed by dimensional analysis. Applying these constraints yields a general equation for P/sub i/ which is equal to rho V/sup 3/l/sub CF//sup 2/F(M/sub A/,theta) where, rho V/sup 3/ is the solar wind kinetic energy density and l/sub CF//sup 2/ is the scale size of the magnetosphere's effective energy ''collection'' region. The function F which depends on M/sub A/, the Alfven Mach number, and on theta, the interplanetary magnetic field clock angle is included in the general equation for P/sub i/ in order to model the magnetohydrodynamic processes which are responsible for solar wind-magnetosphere energy transfer. By assuming the form of the function F, it is possible to further constrain the formula for P/sub i/. This is accomplished by using solar wind data, geomagnetic activity indices, and simple statistical methods. It is found that P/sub i/ is proportional to (rho V/sup 2/)/sup 1/6/VBG(theta) where, rho V/sup 2/ is the solar wind dynamic pressure and VBG(theta) is a rectified version of the solar wind motional electric field. Furthermore, it is found that G(theta), the gating function which modulates the energy input to the magnetosphere, is well represented by a ''leaky'' rectifier function such as sin/sup 4/(theta/2). This function allows for enhanced energy input when the interplanetary magnetic field is oriented southward. This function also allows for some energy input when the interplanetary magnetic field is oriented northward. 9 refs., 4 figs.

  16. Anticipating Juno Observations of the Magnetosphere of Jupiter

    NASA Astrophysics Data System (ADS)

    Bunnell, E.; Fowler, C. M.; Bagenal, F.; Bonfond, B.

    2012-12-01

    The Juno spacecraft will arrive at Jupiter in 2016 and will go into polar orbit. Juno will make the first exploration of the polar regions of Jupiter's vast magnetosphere, combining in situ particles and fields measurements with remote sensing of auroral emissions in the UV, IR and radio. The primary science period comprises ~30 orbits with 11-day periods with a~1.06Rj perijove, allowing Juno to duck under the hazardous synchrotron radiation belts. Apojove is at ~38Rj. The oblateness of the planet causes the orbit to precess with the major axis moving progressively south at about 1 degree per orbit, eventually bringing the spacecraft into the radiation belts. This orbit allows unprecedented views of the aurora and exploration of the auroral acceleration regions. We present an overview of anticipated Juno observations based on models of the Jovian magnetosphere. On approach to Jupiter and over a capture orbit that extends to ~180Rj on the dawn flank, Juno will traverse the magnetosheath, magnetopause and boundary layer regions of the magnetosphere. Due to the high plasma pressures in the magnetospheric plasmasheet the magnetosphere of Jupiter is known to vary substantially with the changes in the solar wind dynamic pressure. We use Ulysses solar wind data obtained around 5 AU to predict the conditions that Juno will observe over the several months it will spend in these boundary regions.

  17. Magnetospheric Exploration: Basic Research with a High Public Purpose

    NASA Astrophysics Data System (ADS)

    Baker, D. N.

    2012-12-01

    From the first in situ measurements of trapped radiation by J.A. Van Allen and coworkers with Explorer 1 to the latest modern satellite observations, magnetospheric research has been an exciting and compelling program of exploration. Evolving understanding of the Earth system and then the extension of this research to the magnetospheres of other planets such as Jupiter, Saturn, and Mercury has been a commingling of certain common themes as well as discovery of strikingly different properties from one system to the next. One key point is that much of the basic research performed concerning the near-Earth magnetospheric region also has profound societal relevance. The studies of magnetospheric properties - especially very high energy particles in the Van Allen belts - are absolutely central to space weather concerns that confront navigation, communications, remote sensing, and other operational human endeavors. It is a privilege as well as a challenge to continue to study magnetospheric problems that both illuminate remote astrophysical processes as well as affect our daily, technology-dependent lives.

  18. Jupiter's magnetosphere: Plasma description from the Ulysses flyby

    SciTech Connect

    Bame, S.J.; Barraclough, B.L.; Feldman, W.C.; Gisler, G.R.; Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Thomsen, M.F. ); Goldstein, B.E.; Neugebauer, M. )

    1992-09-11

    Plasma observations at Jupiter show that the outer regions of the Jovian magnetosphere are remarkably similar to those of Earth. Bow-shock precursor electrons and ions were detected in the upstream solar wind, as at Earth. Plasma changes across the bow shock and properties of the magnetosheath electrons were much like those at Earth, indicating that similar processes are operating. A boundary layer populated by a varying mixture of solar wind and magnetospheric plasmas was found inside the magnetopause, again as at Earth. In the middle magnetosphere, large electron density excursions were detected with a 10-hour periodicity as planetary rotation carried the tilted plasma sheet past Ulysses. Deep in the magnetosphere, Ulysses crossed a region, tentatively described as magnetically connected to the Jovian polar cap on one end and to the interplanetary magnetic field on the other. In the inner magnetosphere and Io torus, where corotation plays a dominant role, measurements could not be made because of extreme background rates from penetrating radiation belt particles.

  19. A Three-Dimensional Global Hybrid Model of the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Wang, X.; Lin, Y.; Lu, S.; Perez, J. D.; Lu, Q.

    2013-12-01

    A 3-D global hybrid simulation code with domain including both the dayside and night side magnetosphere of the Earth has been developed to study the coupling between the solar wind and the magnetosphere. A Cartesian coordinate system is used, with the simulation domain extends from x = -60 RE to +23RE, y = -30 RE to 30RE, and z = -30 RE to 30RE. Nonuniform cell grids are used, with a higher resolution around the regions of the near-Earth plasma sheet. The inner boundary is located at r =3.5 RE. In the simulation, ions are treated as fully kinetic particles, where electrons are treated as a massless fluid. In addition, a cold ion fluid is assumed in the inner magnetosphere within r<6RE. The bow shock and the Earth's magnetosphere form from the interaction between the solar wind and the dipole geomagnetic field. The solar wind carrying the IMF flows into domain from the upstream boundary at x=23RE, while the free conditions are applied at all the other sides of the boundaries. The inner boundary condition at r= 3.5Re is determined by mapping the parallel currents and electric field to the ionosphere. The details of hybrid code and its benchmark are presented. The global structure of the magnetosphere is shown for various solar wind and IMF conditions.

  20. Comparison of the activities of fine-particle size catalysts

    SciTech Connect

    Stohl, F.V.; Diegert, K.V.; Goodnow, D.C.

    1994-12-31

    The objectives of Sandia`s fine-particle size catalyst testing project are to evaluate and compare the activities of the fine-particle size catalysts being developed in DOE/PETCs Advanced Research Coal Liquefaction Program by using standard coal liquefaction test procedures. The standard procedures use Blind Canyon coal, phenanthrene as the reaction solvent, and a factorial experimental design with temperatures from 350{degrees}C to 400{degrees}C, reaction times from 20 to 60 minutes, and catalyst loadings up to 1 wt%. Catalytic activity is measured in terms of tetrahydrofuran conversion, heptane conversion, the amount of 9,10-dihydrophenanthrene in the product, and the gas yield. Several catalysts have been evaluated including a commercially available pyrite, a sulfated iron oxide from the University of Pittsburgh, and several preparations of 6-line ferrihydrites from Pacific Northwest Laboratories. Results have demonstrated that significant differences in activity can be detected among these catalysts.

  1. Clustering and phase behaviour of attractive active particles with hydrodynamics.

    PubMed

    Navarro, Ricard Matas; Fielding, Suzanne M

    2015-10-14

    We simulate clustering, phase separation and hexatic ordering in a monolayered suspension of active squirming disks subject to an attractive Lennard-Jones-like pairwise interaction potential, taking hydrodynamic interactions between the particles fully into account. By comparing the hydrodynamic case with counterpart simulations for passive and active Brownian particles, we elucidate the relative roles of self-propulsion, interparticle attraction, and hydrodynamic interactions in determining clustering and phase behaviour. Even in the presence of an attractive potential, we find that hydrodynamic interactions strongly suppress the motility induced phase separation that might a priori have been expected in a highly active suspension. Instead, we find only a weak tendency for the particles to form stringlike clusters in this regime. At lower activities we demonstrate phase behaviour that is broadly equivalent to that of the counterpart passive system at low temperatures, characterized by regimes of gas-liquid, gas-solid and liquid-solid phase coexistence. In this way, we suggest that a dimensionless quantity representing the level of activity relative to the strength of attraction plays the role of something like an effective non-equilibrium temperature, counterpart to the (dimensionless) true thermodynamic temperature in the passive system. However there are also some important differences from the equilibrium case, most notably with regards the degree of hexatic ordering, which we discuss carefully. PMID:26278520

  2. Virial pressure in systems of spherical active Brownian particles.

    PubMed

    Winkler, Roland G; Wysocki, Adam; Gompper, Gerhard

    2015-09-01

    The pressure of suspensions of self-propelled objects is studied theoretically and by simulation of spherical active Brownian particles (ABPs). We show that for certain geometries, the mechanical pressure as force/area of confined systems can be equally expressed by bulk properties, which implies the existence of a nonequilibrium equation of state. Exploiting the virial theorem, we derive expressions for the pressure of ABPs confined by solid walls or exposed to periodic boundary conditions. In both cases, the pressure comprises three contributions: the ideal-gas pressure due to white-noise random forces, an activity-induced pressure ("swim pressure"), which can be expressed in terms of a product of the bare and a mean effective particle velocity, and the contribution by interparticle forces. We find that the pressure of spherical ABPs in confined systems explicitly depends on the presence of the confining walls and the particle-wall interactions, which has no correspondence in systems with periodic boundary conditions. Our simulations of three-dimensional ABPs in systems with periodic boundary conditions reveal a pressure-concentration dependence that becomes increasingly nonmonotonic with increasing activity. Above a critical activity and ABP concentration, a phase transition occurs, which is reflected in a rapid and steep change of the pressure. We present and discuss the pressure for various activities and analyse the contributions of the individual pressure components. PMID:26221908

  3. Magnetospheric dynamics of trapped solar proton events

    NASA Astrophysics Data System (ADS)

    Larsen, B. A.; Engel, M.; Chen, Y.; Friedel, R. H.

    2012-12-01

    Solar proton events (SEP) are sometimes trapped in the magnetosphere creating a new trapped belt or protons in the L=3 to L=4 range that can last for months. We note that there is a commonly observed and unexplained time gap between the SEP event and flux being observed in the L=3 to L=4 trapping region from the POES spacecraft. We present two hypotheses to explain the time gap and explore each. First the SEP trapping mechanism is thought to be driven by interplanetary shocks, required to drive the protons deep into the magnetosphere to regions where geomagnetic shielding does not normally grant them access where they then can become trapped. The processes that drive the protons are highly peaked at equatorial pitch angles near 90 degrees explaining the time gap as the time required for pitch angle diffusion to change the particles to pitch angles observable by POES in low-Earth orbit. The second hypothesis is that the time gap is the result of radial transport preserving the first adiabatic invariant thus energizing the protons from one energy channel to another. The time gap is then the time required for radial transport to move and energize the particles into the L=3 to L=4 region. Evidence and conclusions about each hypothesis is presented.

  4. Hygroscopic Growth and Activation of Particles containing Algea-Exudate

    NASA Astrophysics Data System (ADS)

    Wex, Heike; Fuentes, Elena; Tsagkogeorgas, Georgios; Voigtländer, Jens; Clauss, Tina; Kiselev, Alexei; Green, David; Coe, Hugh; McFiggans, Gordon; Stratmann, Frank

    2010-05-01

    A large amount of the Earth is covered by oceans, which provide a constant source of marine aerosol particles, produced due to bubble bursting processes that depend on wind speed (O'Dowd and de Leeuw, 2007). In general, marine particles can be assumed to play an important role for the Earth atmosphere on a global scale, due to their abundance and due to their effect on clouds. E.g. marine stratus and stratocumulus clouds contribute about 30% to 40% to the Earth's albedo (Randall et al., 1984). The activation of aerosol particles to cloud droplets depends on the hygroscopic properties of the particles, which, in turn, depend on their chemical composition. For marine particles, is has been and still is discussed what the effects of organic substances being present in the particles might be. These substances originate from marine biota where they enrich at the ocean surface. To mimic marine aerosol particles, algae-exudates of different algae species were mixed with artificial sea-water. These samples were used in the laboratory to produce particles via a bubble bursting process (Fuentes et al., 2009). The hygroscopic growth and activation of the (size selected) particles was measured, using LACIS (Leipzig Aerosol Cloud Interaction Simulator, Stratmann et al., 2004) and the DMT-CCNc (Cloud Condensation Nucleus counter from Droplet Measurement Technologies, Roberts and Nenes, 2005). The hygroscopic growth was measured twice, 3 and 10 seconds after humidification, and no difference in the grown size was detected, i.e. no kinetic effect was observed for the examined time range. From LACIS and CCNc measurements, the hygroscopicity was deduced through determination of the amount of ions being effective in the particle / droplet solution (Rho(ion), Wex et al., 2007). A concentration dependent non-ideal behaviour was found for particles produced from an artificial sea-water sample that contained only inorganic salts, as can be expected (see e.g. Niedermeier et al., 2008

  5. Emergent Ultra-Long-Range Interactions Between Active Particles in Hybrid Active-Inactive Systems

    NASA Astrophysics Data System (ADS)

    Steimel, Joshua; Aragones, Juan; Hu, Helen; Qureshi, Naser; Alexander-Katz, Alfredo

    Particle-particle interactions determine the state of a system. Control over the range and magnitude of such interactions has been an active area of research for decades due to the fundamental challenges it poses in science and technology. Effective interactions between active particles have gathered much attention as they can lead to out-of-equilibrium cooperative states such as flocking. Inspired by nature, where active living cells coexist with lifeless, immobile objects and structures, here we study the effective interactions that appear in systems composed of active and passive mixtures of colloids. Our system is a two dimensional colloidal monolayer composed primarily of passive (inactive) colloids and a very small fraction of active (sinning) ferromagnetic colloids. We find an emergent ultra-long-range attractive interaction between active particles induced by the activity of the spinning particles and mediated by the elasticity of the passive medium. Interestingly, the appearance of such interaction depends on the spinning protocol and has a minimum actuation time scale below which no attraction is observed. Overall, these results clearly show that in the presence of elastic components, active particles can interact across very long distances without any chemical modification of the environment. Such a mechanism might potentially be important for some biological systems and can be harnessed for newer developments in synthetic active soft materials.

  6. The Magnetospheric Multiscale Magnetometers

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Anderson, B. J.; Baumjohann, W.; Bromund, K. R.; Dearborn, D.; Fischer, D.; Le, G.; Leinweber, H. K.; Leneman, D.; Magnes, W.; Means, J. D.; Moldwin, M. B.; Nakamura, R.; Pierce, D.; Plaschke, F.; Rowe, K. M.; Slavin, J. A.; Strangeway, R. J.; Torbert, R.; Hagen, C.; Jernej, I.; Valavanoglou, A.; Richter, I.

    2016-03-01

    The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University's Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored on board so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.

  7. Origins of magnetospheric physics

    SciTech Connect

    Van Allen, J.A.

    1983-01-01

    The history of the scientific investigation of the earth magnetosphere during the period 1946-1960 is reviewed, with a focus on satellite missions leading to the discovery of the inner and outer radiation belts. Chapters are devoted to ground-based studies of the earth magnetic field through the 1930s, the first U.S. rocket flights carrying scientific instruments, the rockoon flights from the polar regions (1952-1957), U.S. planning for scientific use of artificial satellites (1956), the launch of Sputnik I (1957), the discovery of the inner belt by Explorers I and III (1958), the Argus high-altitude atomic-explosion tests (1958), the confirmation of the inner belt and discovery of the outer belt by Explorer IV and Pioneers I-V, related studies by Sputniks II and III and Luniks I-III, and the observational and theoretical advances of 1959-1961. Photographs, drawings, diagrams, graphs, and copies of original notes and research proposals are provided. 227 references.

  8. Ionospheric and magnetospheric plasmapauses'

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Hoffman, J. H.; Maynard, N. C.

    1977-01-01

    During August 1972, Explorer 45 orbiting near the equatorial plane with an apogee of about 5.2 R sub e traversed magnetic field lines in close proximity to those simultaneously traversed by the topside ionospheric satellite ISIS 2 near dusk in the L range 2-5.4. The locations of the Explorer 45 plasmapause crossings during this month were compared to the latitudinal decreases of the H(+) density observed on ISIS 2 near the same magnetic field lines. The equatorially determined plasmapause field lines typically passed through or poleward of the minimum of the ionospheric light ion trough, with coincident satellite passes occurring for which the L separation between the plasmapause and trough field lines was between 1 and 2. Vertical flows of the H(+) ions in the light ion trough as detected by the magnetic ion mass spectrometer on ISIS were directed upward with velocities between 1 and 2 kilometers/sec near dusk on these passes. These velocities decreased to lower values on the low latitude side of the H(+) trough but did not show any noticeable change across the field lines corresponding to the magnetospheric plasmapause.

  9. Guiding catalytically active particles with chemically patterned surfaces

    NASA Astrophysics Data System (ADS)

    Uspal, William; Popescu, Mihail; Dietrich, Siegfried; Tasinkevych, Mykola

    Catalytically active Janus particles in solution create gradients in the chemical composition of the solution along their surfaces, as well as along any nearby container walls. The former leads to self-phoresis, while the latter gives rise to chemi-osmosis, providing an additional contribution to self-motility. Chemi-osmosis strongly depends on the molecular interactions between the diffusing chemical species and the wall. We show analytically, using an approximate ``point-particle'' approach, that by chemically patterning a planar substrate (e.g., by adsorbing two different materials) one can direct the motion of Janus particles: the induced chemi-osmotic flows can cause particles to either ``dock'' at a chemical step between the two materials, or to follow a chemical stripe. These theoretical predictions are confirmed by full numerical calculations. Generically, docking occurs for particles which tend to move away from their catalytic caps, while stripe-following occurs in the opposite case. Our analysis reveals the physical mechanisms governing this behavior.

  10. Ice Nucleation Activity of Various Agricultural Soil Dust Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Schiebel, Thea; Höhler, Kristina; Funk, Roger; Hill, Thomas C. J.; Levin, Ezra J. T.; Nadolny, Jens; Steinke, Isabelle; Suski, Kaitlyn J.; Ullrich, Romy; Wagner, Robert; Weber, Ines; DeMott, Paul J.; Möhler, Ottmar

    2016-04-01

    Recent investigations at the cloud simulation chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere) suggest that agricultural soil dust has an ice nucleation ability that is enhanced up to a factor of 10 compared to desert dust, especially at temperatures above -26 °C (Steinke et al., in preparation for submission). This enhancement might be caused by the contribution of very ice-active biological particles. In addition, soil dust aerosol particles often contain a considerably higher amount of organic matter compared to desert dust particles. To test agricultural soil dust as a source of ice nucleating particles, especially for ice formation in warm clouds, we conducted a series of laboratory measurements with different soil dust samples to extend the existing AIDA dataset. The AIDA has a volume of 84 m3 and operates under atmospherically relevant conditions over wide ranges of temperature, pressure and humidity. By controlled adiabatic expansions, the ascent of an air parcel in the troposphere can be simulated. As a supplement to the AIDA facility, we use the INKA (Ice Nucleation Instrument of the KArlsruhe Institute of Technology) continuous flow diffusion chamber based on the design by Rogers (1988) to expose the sampled aerosol particles to a continuously increasing saturation ratio by keeping the aerosol temperature constant. For our experiments, soil dust was dry dispersed into the AIDA vessel. First, fast saturation ratio scans at different temperatures were performed with INKA, sampling soil dust aerosol particles directly from the AIDA vessel. Then, we conducted the AIDA expansion experiment starting at a preset temperature. The combination of these two different methods provides a robust data set on the temperature-dependent ice activity of various agriculture soil dust aerosol particles with a special focus on relatively high temperatures. In addition, to extend the data set, we investigated the role of biological and organic matter in more

  11. A Full-wave Model for Wave Propagation and Dissipation in the Inner Magnetosphere Using the Finite Element Method

    SciTech Connect

    Ernest Valeo, Jay R. Johnson, Eun-Hwa and Cynthia Phillips

    2012-03-13

    A wide variety of plasma waves play an important role in the energization and loss of particles in the inner magnetosphere. Our ability to understand and model wave-particle interactions in this region requires improved knowledge of the spatial distribution and properties of these waves as well as improved understanding of how the waves depend on changes in solar wind forcing and/or geomagnetic activity. To this end, we have developed a two-dimensional, finite element code that solves the full wave equations in global magnetospheric geometry. The code describes three-dimensional wave structure including mode conversion when ULF, EMIC, and whistler waves are launched in a two-dimensional axisymmetric background plasma with general magnetic field topology. We illustrate the capabilities of the code by examining the role of plasmaspheric plumes on magnetosonic wave propagation; mode conversion at the ion-ion and Alfven resonances resulting from external, solar wind compressions; and wave structure and mode conversion of electromagnetic ion cyclotron waves launched in the equatorial magnetosphere, which propagate along the magnetic field lines toward the ionosphere. We also discuss advantages of the finite element method for resolving resonant structures, and how the model may be adapted to include nonlocal kinetic effects.

  12. Empirical models of the magnetospheric magnetic field

    NASA Technical Reports Server (NTRS)

    Jordan, C. E.

    1994-01-01

    A general overview of magnetospheric modeling is given, along with a more detailed discussion of several empirical models which are widely used. These models are composed of representations of the Earth's main internal field (basically a bipolar field), plus external field contributions due to ring currents (carried by the particles in the Van Allen radiation belts), magnetopause currents (the boundary surface between the Earth's magnetic field and interplanetary magnetic field carried by the solar wind), and tail currents (carried by particles in the neutral sheet of the magnetotail). The empirical models presented here are the Mead-Fairfield, Olsen-Pfitzer tilt-dependent (1977), Tsyganenko-Usamo, Tsyganenko (1987), Olsen-Pfitzer dynamic (1988), Tsyganenko (1989), and Hilmer-Voight models. The derivations, agreement with quiet time and storm time data from the two satellite programs, Spacecraft Charging at High Altitudes (SCATHA) and Combined Release Radiation Effects Satellite (CRRES), and computational requirements of these models are compared.

  13. Therapeutic activity of modified U1 core spliceosomal particles

    PubMed Central

    Rogalska, Malgorzata Ewa; Tajnik, Mojca; Licastro, Danilo; Bussani, Erica; Camparini, Luca; Mattioli, Chiara; Pagani, Franco

    2016-01-01

    Modified U1 snRNAs bound to intronic sequences downstream of the 5′ splice site correct exon skipping caused by different types of mutations. Here we evaluate the therapeutic activity and structural requirements of these exon-specific U1 snRNA (ExSpeU1) particles. In a severe spinal muscular atrophy, mouse model, ExSpeU1, introduced by germline transgenesis, increases SMN2 exon 7 inclusion, SMN protein production and extends life span. In vitro, RNA mutant analysis and silencing experiments show that while U1A protein is dispensable, the 70K and stem loop IV elements mediate most of the splicing rescue activity through improvement of exon and intron definition. Our findings indicate that precise engineering of the U1 core spliceosomal RNA particle has therapeutic potential in pathologies associated with exon-skipping mutations. PMID:27041075

  14. Phase Segregation of Passive Advective Particles in an Active Medium.

    PubMed

    Das, Amit; Polley, Anirban; Rao, Madan

    2016-02-12

    Localized contractile configurations or asters spontaneously appear and disappear as emergent structures in the collective stochastic dynamics of active polar actomyosin filaments. Passive particles which (un)bind to the active filaments get advected into the asters, forming transient clusters. We study the phase segregation of such passive advective scalars in a medium of dynamic asters, as a function of the aster density and the ratio of the rates of aster remodeling to particle diffusion. The dynamics of coarsening shows a violation of Porod behavior; the growing domains have diffuse interfaces and low interfacial tension. The phase-segregated steady state shows strong macroscopic fluctuations characterized by multiscaling and intermittency, signifying rapid reorganization of macroscopic structures. We expect these unique nonequilibrium features to manifest in the actin-dependent molecular clustering at the cell surface. PMID:26919022

  15. Phase Segregation of Passive Advective Particles in an Active Medium

    NASA Astrophysics Data System (ADS)

    Das, Amit; Polley, Anirban; Rao, Madan

    2016-02-01

    Localized contractile configurations or asters spontaneously appear and disappear as emergent structures in the collective stochastic dynamics of active polar actomyosin filaments. Passive particles which (un)bind to the active filaments get advected into the asters, forming transient clusters. We study the phase segregation of such passive advective scalars in a medium of dynamic asters, as a function of the aster density and the ratio of the rates of aster remodeling to particle diffusion. The dynamics of coarsening shows a violation of Porod behavior; the growing domains have diffuse interfaces and low interfacial tension. The phase-segregated steady state shows strong macroscopic fluctuations characterized by multiscaling and intermittency, signifying rapid reorganization of macroscopic structures. We expect these unique nonequilibrium features to manifest in the actin-dependent molecular clustering at the cell surface.

  16. Materials for Active Engagement in Nuclear and Particle Physics Courses

    NASA Astrophysics Data System (ADS)

    Loats, Jeff; Schwarz, Cindy; Krane, Ken

    2013-04-01

    Physics education researchers have developed a rich variety of research-based instructional strategies that now permeate many introductory courses. Carrying these active-engagement techniques to upper-division courses requires effort and is bolstered by experience. Instructors interested in these methods thus face a large investment of time to start from scratch. This NSF-TUES grant, aims to develop, test and disseminate active-engagement materials for nuclear and particle physics topics. We will present examples of these materials, including: a) Conceptual discussion questions for use with Peer Instruction; b) warm-up questions for use with Just in Time Teaching, c) ``Back of the Envelope'' estimation questions and small-group case studies that will incorporate use of nuclear and particle databases, as well as d) conceptual exam questions.

  17. Therapeutic activity of modified U1 core spliceosomal particles.

    PubMed

    Rogalska, Malgorzata Ewa; Tajnik, Mojca; Licastro, Danilo; Bussani, Erica; Camparini, Luca; Mattioli, Chiara; Pagani, Franco

    2016-01-01

    Modified U1 snRNAs bound to intronic sequences downstream of the 5' splice site correct exon skipping caused by different types of mutations. Here we evaluate the therapeutic activity and structural requirements of these exon-specific U1 snRNA (ExSpeU1) particles. In a severe spinal muscular atrophy, mouse model, ExSpeU1, introduced by germline transgenesis, increases SMN2 exon 7 inclusion, SMN protein production and extends life span. In vitro, RNA mutant analysis and silencing experiments show that while U1A protein is dispensable, the 70K and stem loop IV elements mediate most of the splicing rescue activity through improvement of exon and intron definition. Our findings indicate that precise engineering of the U1 core spliceosomal RNA particle has therapeutic potential in pathologies associated with exon-skipping mutations. PMID:27041075

  18. Energetic Electron Transport in the Inner Magnetosphere During Geomagnetic Storms and Substorms

    NASA Technical Reports Server (NTRS)

    McKenzie, D. L.; Anderson, P. C.

    2005-01-01

    We propose to examine the relationship of geomagnetic storms and substorms and the transport of energetic particles in the inner magnetosphere using measurements of the auroral X-ray emissions by PIXIE. PIXIE provides a global view of the auroral oval for the extended periods of time required to study stormtime phenomena. Its unique energy response and global view allow separation of stormtime particle transport driven by strong magnetospheric electric fields from substorm particle transport driven by magnetic-field dipolarization and subsequent particle injection. The relative importance of substorms in releasing stored magnetospheric energy during storms and injecting particles into the inner magnetosphere and the ring current is currently hotly debated. The distribution of particles in the inner magnetosphere is often inferred from measurements of the precipitating auroral particles. Thus, the global distributions of the characteristics of energetic precipitating particles during storms and substorms are extremely important inputs to any description or model of the geospace environment and the Sun-Earth connection. We propose to use PIXIE observations and modeling of the transport of energetic electrons to examine the relationship between storms and substorms.

  19. Internally Driven, Dynamical Behaviour of Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Pilkington, N. M.; Achilleos, N. A.; Arridge, C. S.; Guio, P.; Masters, A.; Sergis, N.; Coates, A. J.; Dougherty, M. K.

    2014-12-01

    We have used 7 years of in-situ magnetic and and particle data from the CAPS and MIMI instruments onboard the Cassini spacecraft to study Saturn's magnetopause boundary throughout the mission. In addition to the solar wind dynamic pressure, we find that magnetopause size is also strongly modulated by changing conditions inside the magnetosphere for which the usual scaling law (stand-off distance versus dynamic pressure) cannot account. At a fixed dynamic pressure, the stand-off distance can vary by 10-15 Saturn radii (Rs) depending on the plasma pressure inside the magnetosphere. We have quantified the variability in stand-off distance as a function of both dynamic pressure and interior plasma beta, both of which show considerable variability at Saturn. We modify the power law that is usually used to specify the size of a magnetosphere as a function of dynamic pressure by adding an additional dependency on plasma beta. We have also fitted empirical surfaces, using both 'old' and 'new' power laws, to observed magnetopause crossings. To describe the magnetopause shape and scale, we have used the original analytical form of Shue et al. (1997), as modified by Pilkington et al. (2014) to incorporate polar flattening. Using the new power law reduces the discrepancy between where the boundary is observed and where the model predicts it should be by ~1Rs on average, which is ~20% of the typical r.m.s. deviation between observed and modelled location. Hence, the internal variation in plasma beta strongly influences the magnetopause location at Saturn and, presumably, must also be taken into account for Jupiter and other magnetised planets with strong internal plasma sources.

  20. Dust in Jupiter's magnetosphere. I - Physical processes. II - Origin of the ring. III - Time variations. IV - Effect on magnetospheric electrons and ions

    NASA Technical Reports Server (NTRS)

    Morfill, G. E.; Gruen, E.; Johnson, T. V.

    1980-01-01

    The physical processes acting on charged microscopic dust grains in the Jovian atmosphere involve electromagnetic forces which dominate dust particle dynamics and diffusion across field lines resulting from random charge fluctuations of the dust grains. A model of the Jovian ring hypothesizes that the 'visible' ring particles are produced by erosive collisions between an assumed population of kilometer-sized parent bodies and submicron-sized magnetospheric dust particles. Fluctuations in the ring topology and intensity are determined over various time scales, showing that the ring is a quasipermanent and quasistable characteristic of the Jovian system. Finally, the interaction of the Jovian energetic belt electrons and the Jovian plasma with an ambient dust population is examined; the distribution of dust ejected from Io in the inner magnetosphere and losses of magnetospheric ions and electrons due to direct collisions with charged dust particles are calculated.

  1. RESISTIVE SOLUTIONS FOR PULSAR MAGNETOSPHERES

    SciTech Connect

    Li, Jason; Spitkovsky, Anatoly; Tchekhovskoy, Alexander

    2012-02-10

    The current state of the art in the modeling of pulsar magnetospheres invokes either the vacuum or force-free limits for the magnetospheric plasma. Neither of these limits can simultaneously account for both the plasma currents and the accelerating electric fields that are needed to explain the morphology and spectra of high-energy emission from pulsars. To better understand the structure of such magnetospheres, we combine accelerating fields and force-free solutions by considering models of magnetospheres filled with resistive plasma. We formulate Ohm's law in the minimal velocity fluid frame and construct a family of resistive solutions that smoothly bridges the gap between the vacuum and the force-free magnetosphere solutions. The spin-down luminosity, open field line potential drop, and the fraction of open field lines all transition between the vacuum and force-free values as the plasma conductivity varies from zero to infinity. For fixed inclination angle, we find that the spin-down luminosity depends linearly on the open field line potential drop. We consider the implications of our resistive solutions for the spin-down of intermittent pulsars and sub-pulse drift phenomena in radio pulsars.

  2. The Earth’s magnetosphere response to interplanetary medium conditions on January 21-22, 2005 and on December 14-15, 2006

    NASA Astrophysics Data System (ADS)

    Kalegaev, V. V.; Vlasova, N. A.

    2014-08-01

    The Earth’s magnetosphere response to interplanetary medium conditions on January 21-22, 2005 and on December 14-15, 2006 has been studied. The analysis of solar wind parameters measured by ACE spacecraft, of geomagnetic indices variations, of geomagnetic field measured by GOES 11, 12 satellites, and of energetic particle fluxes measured by POES 15, 16, 17 satellites was performed together with magnetospheric modeling based in terms of A2000 paraboloid model. We found the similar dynamics of three particle populations (trapped, quasi-trapped, and precipitating) during storms of different intensities developed under different external conditions: the maximal values of particle fluxes and the latitudinal positions of the isotropic boundaries were approximately the same. The main sources caused RC build-up have been determined for both magnetic storms. Global magnetospheric convection controlled by IMF and substorm activity driven magnetic storm on December 14-15, 2006. Extreme solar wind pressure pulse was mainly responsible for RC particle injection and unusual January 21, 2005 magnetic storm development under northward IMF during the main phase.

  3. Phase transition-like behavior of the magnetosphere during substorms

    NASA Astrophysics Data System (ADS)

    Sitnov, M. I.; Sharma, A. S.; Papadopoulos, K.; Vassiliadis, D.; Valdivia, J. A.; Klimas, A. J.; Baker, D. N.

    2000-06-01

    The behavior of substorms as sudden transitions of the magnetosphere is studied using the Bargatze et al. [1985] data set of the solar wind induced electric field vBs and the auroral electrojet index AL. The data set is divided into three subsets representing different levels of activity, and they are studied using the singular spectrum analysis. The points representing the evolution of the magnetosphere in the subspace of the eigenvectors corresponding to the three largest eigenvalues can be approximated by two-dimensional manifolds with a relative deviation of 10-20%. For the first two subsets corresponding to small and medium activity levels the manifolds have a pleated structure typical of the cusp catastrophe. The dynamics of the magnetosphere near these pleated structures resembles the hysteresis phenomenon typical of first-order phase transitions. The reconstructed manifold is similar to the ``temperature-pressure-density'' diagrams of equilibrium phase transitions. The singular spectra of vBs, AL, and combined data have the power law dependence typical of second-order phase transitions and self-organized criticality. The magnetosphere thus exhibits the signatures of both self-organization and self-organized criticality. It is concluded that the magnetospheric substorm is neither a pure catastrophe of the low-dimensional system nor a random set of avalanches of different scales described by the simple sandpile models. The substorms behave like nonequilibrium phase transitions, with features of both first- and second-order phase transitions.

  4. Measurements of meteor smoke particles during the ECOMA-2006 campaign: 1. Particle detection by active photoionization

    NASA Astrophysics Data System (ADS)

    Rapp, Markus; Strelnikova, Irina

    2009-03-01

    We present a new design of an in situ detector for the study of meteor smoke particles (MSPs) in the middle atmosphere. This detector combines a classical Faraday cup with a xenon-flashlamp for the active photoionization/photodetachment of MSPs and the subsequent detection of corresponding photoelectrons. This instrument was successfully launched in September 2006 from the Andøya Rocket Range in Northern Norway. A comparison of photocurrents measured during this rocket flight and measurements performed in the laboratory proves that observed signatures are truly due to photoelectrons. In addition, the observed altitude cut-off at 60 km (i.e., no signals were observed below this altitude) is fully understood in terms of the mean free path of the photoelectrons in the ambient atmosphere. This interpretation is also proven by a corresponding laboratory experiment. Consideration of all conceivable species which can be ionized by the photons of the xenon-flashlamp demonstrates that only MSPs can quantitatively explain the measured currents below an altitude of 90 km. Above this altitude, measured photocurrents are most likely due to photoionization of nitric oxide. In conclusion, our results demonstrate that the active photoionization and subsequent detection of photoelectrons provides a promising new tool for the study of MSPs in the middle atmosphere. Importantly, this new technique does not rely on the a priori charge of the particles, neither is the accessible particle size range severely limited by aerodynamical effects. Based on the analysis described in this study, the geophysical interpretation of our measurements is presented in the companion paper by Strelnikova, I., et al. [2008. Measurements of meteor smoke particles during the ECOMA-2006 campaign: 2. results. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.011].

  5. Magnetospheres of the outer planets. Progress report

    SciTech Connect

    Van Allen, J.A.

    1985-04-01

    The physical conditions that are necessary for the existence of a planetary magnetosphere are reviewed. These general considerations and some specific evidence are then combined to make forecasts of the probable existence and nature of magnetospheres of Uranus and Neptune.

  6. Antibacterial activity of carbon-coated zinc oxide particles.

    PubMed

    Sawai, Jun; Yamamoto, Osamu; Ozkal, Burak; Nakagawa, Zenbe-E

    2007-03-01

    Particles of ZnO coated with carbon (ZnOCC) were prepared and evaluated for their antibacterial activity. ZnO powder and poly(vinyl alcohol) (PVA) (polymerization degree: 2,000-95,000) were mixed at a mass ratio (ZnO/PVA) of 1, and then heated at 500-650 degree C for 3 h under argon gas with a flow rate of 50ml/min. Carbon deposited on the ZnOCC surface was amorphous as revealed by X-ray diffraction studies. The ZnOCC particles maintained their shape in water, even under agitation. The antibacterial activity of ZnOCC powder against Staphylococcus aureus was evaluated quantitatively by measuring the change in the electrical conductivity of the growth medium caused by bacterial metabolism (conductimetric assay). The conductivity curves obtained were analyzed using the growth inhibition kinetic model proposed by Takahashi for calorimetric evaluation, allowing the estimation of the antibacterial efficacy and kinetic parameters of ZnOCC. In a previous study, when ZnO was immobilized on materials, such as activated carbon, the amount of ZnO immobilized was approximately 10-50%, and the antibacterial activity markedly decreased compared to that of the original ZnO. On the other hand, the ZnOCC particles prepared in this study contained approximately 95% ZnO and possessed antibacterial activity similar to that of pure ZnO. The carbon-coating treatment could maintain the antibacterial efficacy of the ZnO and may be useful in the develop-ment of multifunctional antimicrobial materials. PMID:17408004

  7. International cooperation in magnetospheric physics.

    NASA Astrophysics Data System (ADS)

    Roederer, J. G.

    International scientific cooperation in the geosciences started long ago. The main driving force was the need to make measurements simultaneously at different points of the globe. Today, especially in magnetospheric physics, there are additional reasons, one of which is the need to marshal human resources on a world-wide scale to study and understand the ever-increasing complexities of the system. The solution of "global" problems of magnetospheric physics calls for a new mission-oriented mode of work, based on a carefully planned community approach. An internationally coordinated interplay between experiment, theory and computer simulation studies is necessary, as well as a new interactive mode of sharing information and data. In this age of endemically declining budgets for basic science, the international community of magnetospheric physicists must join in an all-out effort to chart their work according to consensus priorities and it must devise strategies to transmit the excitement of their science effectively to the world public.

  8. Emergent ultra-long-range interactions between active particles in hybrid active-inactive systems.

    PubMed

    Steimel, Joshua P; Aragones, Juan L; Hu, Helen; Qureshi, Naser; Alexander-Katz, Alfredo

    2016-04-26

    Particle-particle interactions determine the state of a system. Control over the range of such interactions as well as their magnitude has been an active area of research for decades due to the fundamental challenges it poses in science and technology. Very recently, effective interactions between active particles have gathered much attention as they can lead to out-of-equilibrium cooperative states such as flocking. Inspired by nature, where active living cells coexist with lifeless objects and structures, here we study the effective interactions that appear in systems composed of active and passive mixtures of colloids. Our systems are 2D colloidal monolayers composed primarily of passive (inactive) colloids, and a very small fraction of active (spinning) ferromagnetic colloids. We find an emergent ultra-long-range attractive interaction induced by the activity of the spinning particles and mediated by the elasticity of the passive medium. Interestingly, the appearance of such interaction depends on the spinning protocol and has a minimum actuation timescale below which no attraction is observed. Overall, these results clearly show that, in the presence of elastic components, active particles can interact across very long distances without any chemical modification of the environment. Such a mechanism might potentially be important for some biological systems and can be harnessed for newer developments in synthetic active soft materials. PMID:27071096

  9. Pseudobreakup and substorm growth phase in the ionosphere and magnetosphere

    NASA Technical Reports Server (NTRS)

    Koskinen, H. E. J.; Lopez, R. E.; Pellinen, R. J.; Pulkkinen, T. I.; Baker, D. N.; Bosinger, T.

    1993-01-01

    Observations made during the growth phase and the onset of a substorm on August 31, 1986 are presented. About 20 min after the epsilon parameter at the magnetopause had exceeded 10 exp 11 W, magnetic field dipolarization with an increase of energetic particle fluxes was observed by the AMPTE Charge Composition Explorer (CCE) spacecraft at the geocentric distance of 8.7 R(E) close to magnetic midnight. The event exhibited local signatures of a substorm onset at AMPTE CCE and a weak wedgelike current system in the midnight sector ionosphere, but did not lead to a full-scale substorm expansion; neither did it produce large particle injections at GEO. Only after another 20 min of continued growth phase could the entire magnetosphere-ionosphere system allow the onset of a regular substorm expansion. The initial activation is interpreted as a 'pseudobreakup'. We examine the physical conditions in the near-Earth plasma sheet and analyze the development in the ionosphere using ground-based magnetometers and electric field observations from the STARE radar.

  10. Behavior of outer radiation zone and a new model of magnetospheric substorm.

    NASA Technical Reports Server (NTRS)

    Parks, G. K.; Laval, G.; Pellat, R.

    1972-01-01

    This paper presents particle data obtained from synchronous altitudes and attempts to evaluate the origin and nature of particle flux variations observed during substorms. The correlated particle intensities, time variations, and energy spectrums are compared between the equatorial and auroral zones. The correlated particle and field observations during substorms are tied together and a model of magnetospheric substorms is derived. Among the features predicted by the model is the poleward expansion of visual auroras observed at the onset of magnetospheric substorms. The model also explains how substorms are triggered in a few minutes time scale during sudden commencements.

  11. Magnetospheric imaging with low-energy neutral atoms.

    PubMed Central

    McComas, D J; Barraclough, B L; Elphic, R C; Funsten, H O; Thomsen, M F

    1991-01-01

    Global imaging of the magnetospheric charged particle population can be achieved by remote measurement of the neutral atoms produced when magnetospheric ions undergo charge exchange with cold exospheric neutral atoms. Previously suggested energetic neutral atom imagers were only able to measure neutral atoms with energies typically greater than several tens of keV. A laboratory prototype has been built and tested for a different type of space plasma neutral imaging instrument, which allows neutral atoms to be imaged down to <1 keV. Such low-energy measurements provide greater sensitivity for imaging the terrestrial magnetosphere and allow the bulk of the magnetospheric ion distribution, typically centered below 10 keV, to be observed rather than just the high-energy tail of the distribution. The low-energy neutral atom measurements are made possible by utilizing charge state modifications that occur when an initially neutral atom passes through an ultrathin carbon foil. Oxygen, for example, is highly electronegative, and for energies of approximately 10-30 keV, the O- yield is approximately 30%, essentially independent of the charge state of the incident oxygen atom. These ions are energy per charge analyzed, and the UV background is rejected by using an electrostatic analyzer. Imaging of other ion species, such as hydrogen, could also be accomplished by using ultrathin foil-induced charge state modifications. The technique described in this paper provides a method for imaging charge exchange neutrals from the terrestrial magnetosphere and would also have applications for similar imaging in other planetary or cometary environs. The Inner Magnetosphere Imaging Mission, which the National Aeronautics and Space Administration is presently considering, would provide a nearly ideal platform for low-energy neutral atom imaging, and such measurements would substantially enhance the scientific yield of this mission. PMID:11607229

  12. Leakage of magnetospheric ions into the magnetosheath along reconnected field lines at the dayside magnetopause

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Hovestadt, D.; Klecker, B.; Ipavich, F. M.; Gloeckler, G.

    1981-01-01

    Strong evidence is presented for escape of magnetospheric particles along reconnected field lines into the magnetosheath, using observations of approximately 30 to approximately 120-keV/charge protons and alpha particles made by the Max-Planck-Institut/University of Maryland instrument on Isee 1. During three magnetopause crossings, which have been identified from tangential stress balance analysis as reconnection events, the magnetospheric particle distribution extends well into the magnetosheath, and the particles in the magnetosheath show a strong anisotropy along the magnetic field. The proton to alpha particle ratio in this layer as well as in distinct bursts within the magnetosheath is the same as this ratio within the magnetosphere (at equal energy per charge). It is concluded that the most likely explanation for these observations is that magnetospheric particles are escaping along reconnected field lines into the magnetosheath. It is argued that magnetospheric particles are seen in the magnetosheath up to the reconnection separatrix, and the magnetosheath bursts are interpreted as multiple encounters of this magnetosheath layer by the satellite due to boundary motions.

  13. Rare Suprathermal Heavy Ions in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Christon, S. P.; Hamilton, D. C.; Mitchell, D. G.; Krimigis, S. M.; DiFabio, R. D.

    2013-12-01

    The Cassini/MIMI/CHEMS ion spectrometer has measured suprathermal (~83-167 keV/e) ions in Saturn's magnetosphere since mid-2004. We report on three rare, heavy ion groups measured in Saturn's ~4-20 Rs magnetosphere at ~40, ~46, and ~56 amu/e, with the separation from other species best at higher mass. These masses suggest possible singly-charged ion identifications as Ar+, CO2+, and Fe+, respectively. The presence of these species or compounds containing them has been suggested in composition studies of Saturn's particle populations using data from other instruments on Cassini. The observed rare ion intensities are highly variable in time and space. Broad temporal and spatial averaging is needed to examine these rare ion groups because their detection levels are much lower than the dominant water ion group, W+ (which includes O+, OH+, H2O+, and H3O+). W+ itself can be quite variable. We show that these rare ions display unique spatial and temporal variations, with similarities and differences from the dominant ion group W+ as well as O2+ and M28+, all local origin ions. We compare and contrast these rare, heavy ion species to W+ and the recently characterized [Christon et al., 2013, 10.1002/jgra.50383] minor ions M28+ (C2H5+, HCNH+, N2+, and/or CO+) and O2+ (M32+).

  14. The Comprehensive Inner Magnetosphere-Ionosphere Model

    NASA Astrophysics Data System (ADS)

    Fok, M.-C.; Buzulukova, N. Y.; Chen, S.-H.; Glocer, A.; Nagai, T.; Valek, P.; Perez, J. D.

    2014-09-01

    Simulation studies of the Earth's radiation belts and ring current are very useful in understanding the acceleration, transport, and loss of energetic particles. Recently, the Comprehensive Ring Current Model (CRCM) and the Radiation Belt Environment (RBE) model were merged to form a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. CIMI solves for many essential quantities in the inner magnetosphere, including ion and electron distributions in the ring current and radiation belts, plasmaspheric density, Region 2 currents, convection potential, and precipitation in the ionosphere. It incorporates whistler mode chorus and hiss wave diffusion of energetic electrons in energy, pitch angle, and cross terms. CIMI thus represents a comprehensive model that considers the effects of the ring current and plasmasphere on the radiation belts. We have performed a CIMI simulation for the storm on 5-9 April 2010 and then compared our results with data from the Two Wide-angle Imaging Neutral-atom Spectrometers and Akebono satellites. We identify the dominant energization and loss processes for the ring current and radiation belts. We find that the interactions with the whistler mode chorus waves are the main cause of the flux increase of MeV electrons during the recovery phase of this particular storm. When a self-consistent electric field from the CRCM is used, the enhancement of MeV electrons is higher than when an empirical convection model is applied. We also demonstrate how CIMI can be a powerful tool for analyzing and interpreting data from the new Van Allen Probes mission.

  15. Magnetosphere, rings, and moons of Uranus

    SciTech Connect

    Cheng, A.F.

    1984-10-01

    The observation of an ultraviolet aurora on Uranus implies the existence of a magnetosphere. It is suggested that the magnetospheres of Uranus and Saturn may be very similar. Charged particle sputtering of water ice surfaces on the Uranian moons may maintain an oxygen ion plasma torus similar to the heavy ion plasma torus at Saturn. Atmospheric cosmic ray albedo neutron decay may sustain an inner radiation belt with omnidirectional proton fluxes. If the 100 keV ion fluxes near 7 RU are similar to Saturnian ion fluxes at such energies, the Uranian aurora may be maintained by ion precipitation from the radiation belts at nearly the strong diffusion rate. This mechanism predicts comparable aurorae over both magnetic poles of Uranus, in contrast with the Faraday disc dynamo mechanism, which powers an aurora only over the sunlit pole of uranus. If, however, the 100 kev ion fluxes at Uranus are comparable to those at Saturn, any exposed methane ice surfaces on the moons and rings of Uranus would be quickly transformed by ion impacts to a black, carbonaceous polymer.

  16. Simulations of double layers in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Fu, X.; Cowee, M.; Gary, S. P.; Winske, D.

    2015-12-01

    A double layer (DL) is a nonlinear electrostatic structure consisting of two layers of opposite charge in the plasma, with a characteristic potential jump and unipolar electric field. Previous observations and simulations of DLs in the auroral region showed that those DLs are closely related to ion acoustic waves and typically propagate at ion sound speed. However, recent observation of DLs in the magnetosphere near the equator shows that some DLs propagate at a speed much greater than ion sound speed, inferring a different type of DL that may be associated with electron acoustic waves. In this study, we investigate the formation of DLs in two scenarios in the magnetosphere using particle-in-cell simulations. First, in a current-carrying uniform plasma, we artificially change the ion to electron mass ratio to study the transition from ion-acoustic DLs to electron-acoustic structures. Second, we study the formation of DLs at the boundary of two electron populations with different temperatures. These results may explain recent observations of different types of nonlinear electrostatic structures by Van Allen Probes.

  17. The Inner Magnetosphere Imager mission

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.

    1994-01-01

    The Inner Magnetosphere Imager (IMI) mission will carry instruments to globally image energetic neutral atoms, far and extreme ultraviolet light, and X-rays. These imagers will see the ring current, inner plasmasheet, plasmasphere, aurora, and geocorona. With these observations it will be possible, for the first time, to develop an understanding of the global shape of the inner magnetosphere and the interrelationships between its parts. Seven instruments are currently envisioned on a single spinning spacecraft with a despun platform. IMI will be launched into an elliptical, polar orbit with an apogee of approximately 7 Earth radii altitude and perigee of 4800 km altitude.

  18. The Inner Magnetosphere Imager Mission

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.

    1994-01-01

    The Inner Magnetosphere Imager (IMI) mission will carry instruments to globally image energetic neutral atoms, far and extreme ultraviolet light, and X rays. These imagers will see the ring current inner plasmasheet, plasmasphere, aurora, and geocorona. With these observations it will be possible, for the first time, to develop an understanding of the global shape of the inner magnetosphere and the interrelationships between its parts. Seven instruments are currently envisioned on a single spinning spacecraft with a despun platform. IMI will be launched into an elliptical, polar orbit with an apogee of approximately 7 Earth radii altitude and perigee of 4800 km altitude.

  19. Precompaction irradiation effects: Particles from an early active sun?

    NASA Technical Reports Server (NTRS)

    Caffee, M. W.; Goswami, J. N.; Hohenberg, C. M.; Swindle, T. D.

    1986-01-01

    Two recent studies have shown that solar flare irradiated grains from Murchison and Kapoeta have excess spallogenic Ne-21 compared to unirradiated grains, indicating large precompaction particle irradiation effects. The quantity of cosmogenic neon in these grains presents serious difficulties for either galactic cosmic ray or normal solar flare sources. In the first study it was suggested that the effect might be the result of exposure to an early active sun. The more recent experiment both confirms the earlier results and provides constraints on the characteristic energy spectrum on the irradiation. The first results were obtained from Murchison olivines and Kapoeta pyroxenes by mass spectrometric analysis of sets of grains selected on the basis of the presence or absence of solar flare particle tracks. In the second work plagioclase feldspar grains from Kapoeta were studied.

  20. Magnetospheric electrostatic emissions and cold plasma densities

    NASA Technical Reports Server (NTRS)

    Hubbard, R. F.; Birmingham, T. J.

    1978-01-01

    A synoptic study of electric wave, magnetometer, and plasma data from IMP-6 was carried out for times when banded electrostatic waves are observed between harmonics of the electron gyrofrequency in the earth's outer magnetosphere. Four separate classes of such waves were previously identified. The spatial and temporal occurrences of waves in each class are summarized here, as are correlations of occurrence with geomagnetic activity. Most importantly, associations between the observations of waves of different classes and the relative portions of cold and hot electrons present at the position of the spacecraft are established. Finally, evidence for the signature of the loss cone is sought in the plasma data.

  1. The importance of gradients in particle activity during sediment transport: Insights from a probabilistic description of particle motions

    NASA Astrophysics Data System (ADS)

    Furbish, D. J.

    2009-04-01

    Sediment particles transported by rainsplash, by bioturbation, and as bedload in turbulent flows, undergo motions that are quasi-random in magnitude and direction. Moreover, these motions characteristically are intermittent, in that particles are mostly at rest most of the time, and heterogeneous, in that the volumetric or areal concentration of particles in motion at any instant is spatially patchy. These particle motions can be formulated as a stochastic processes involving both advective and dispersive parts. By taking into account the intermittent activity of particles, and separating this activity from the physics of motion in the parametric description of transport, the formulation indicates that gradients in particle activity can have a key role in transport. The formulation illustrates, for example, how the growth of soil mounds beneath desert shrubs involves differential rainsplash that initially causes more grains to be splashed inward beneath protective shrub canopies than outward. This ‘harvesting' of nearby soil material, including nutrients, means that shrubs locally participate in regulating the rate sediment transport down a hillslope. With soil bioturbation, spatial variations in the disturbance frequency strongly influence the mixing of soil constituents, including distinct particle fractions (such as specific size or mineral fractions, seeds, or debitage), or elements and compounds adsorbed to particles. The formulation also provides a probabilistic version of the Exner equation. During bedload transport, gradients in particle activity, through both advective and dispersive effects, may contribute importantly to the local divergence of the particle flux, thereby influencing initial bedform growth.

  2. The magnetosphere of uranus: hot plasma and radiation environment.

    PubMed

    Krimigis, S M; Armstrong, T P; Axford, W I; Cheng, A F; Gloeckler, G; Hamilton, D C; Keath, E P; Lanzerotti, L J; Mauk, B H

    1986-07-01

    The low-energy charged-particle (LECP) instrument on Voyager 2 measured lowenergy electrons and ions near and within the magnetosphere of Uranus. Initial analysis of the LECP measurements has revealed the following. (i) The magnetospheric particle population consists principally of protons and electrons having energies to at least 4 and 1.2 megaelectron volts, respectively, with electron intensities substantially excceding proton intensities at a given energy. (ii) The intensity profile for both particle species shows evidence that the particles were swept by planetry satellites out to at least the orbit of Titania. (iii) The ion and electron spectra may be described by a Maxwellian core at low energies (less than about 200 kiloelectron volts) and a power law at high energies (greater than about 590 kiloelectron volts; exponentmicro, 3 to 10) except inside the orbit of Miranda, where power-law spectra (micro approximately 1.1 and 3.1 for electrons and protons, respectively) are observed. (iv) At ion energies between 0.6 and 1 megaelectron volt per nucleon, the composition is dominated by protons with a minor fraction (about 10(-3)) of molecular hydrogen; the lower limit for the ratio of hydrogen to helium is greater than 10(4). (v) The proton population is sufficiently intense that fluences greater than 10(16) per square centimeter can accumulate in 10(4) to 10(') years; such fluences are sufficient to polymerize carbon monoxide and methane ice surfaces. The overall morphology of Uranus' magnetosphere resembles that of Jupiter, as evidenced by the fact that the spacecraft crossed the plasma sheet through the dawn magnetosheath twice per planetary rotation period (17.3 hours). Uranus' magnetosphere differs from that of Jupiter and of Saturn in that the plasma 1 is at most 0.1 rather than 1. Therefore, little distortion ofthe field is expected from particle loading at distances less than about 15 Uranus radii. PMID:17812897

  3. MESSENGER Observations of Reconnection and Its Effects on Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Boardsen, Scott A.; Gloeckler, George; Gold, Robert E.; Ho, George C.; Imber, Suzanne M.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Nittler, Larry R.; Raines, Jim M.; Sarantos, Menelaos; Schriver, David; Solomon, Sean C.; Starr, Richard D.; Travnicek, Pavel; Zurbuchen, Thomas H.

    2010-01-01

    During MESSENGER's second and third flybys of Mercury on October 6, 2008 and September 29, 2009, respectively, southward interplanetary magnetic fields produced very intense reconnection signatures in the dayside and nightside magnetosphere and very different systemlevel responses. The IMF during the second flyby was continuously southward and the magnetosphere appeared very active with very large magnetic fields normal to the magnetopause and the generation of flux transfer events at the magnetopause and plasmoids in the tail current sheet every 30 s to 90 s. However, the strength and direction of the tail magnetic field was very stable. In contrast the third flyby experienced a variable IMF with it varying from north to south on timescales of minutes. Although the MESSENGER measurements were limited this time to the nightside magnetosphere, numerous examples of plasmoid release in the tail were detected, but they were not periodic. Rather, plasmoid release was highly correlated with the four large enhancements of the tail magnetic field (i.e. by factors > 2) with durations of approx. 2 - 3 min. The increased flaring of the magnetic field during these intervals indicates that the enhancements were caused by loading of the tail with magnetic flux transferred from the dayside magnetosphere. New analyses of the second and third flyby observations of reconnection and its system-level effects will be presented. The results will be examined in light of what is known about the response of the Earth's magnetosphere to variable versus steady southward IMF.

  4. Twist-induced Magnetosphere Reconfiguration for Intermittent Pulsars

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Yu, Cong; Tong, Hao

    2016-08-01

    We propose that the magnetosphere reconfiguration induced by magnetic twists in the closed field line region can account for the mode switching of intermittent pulsars. We carefully investigate the properties of axisymmetric force-free pulsar magnetospheres with magnetic twists in closed field line regions around the polar caps. The magnetosphere with twisted closed lines leads to enhanced spin-down rates. The enhancement in spin-down rate depends on the size of the region with twisted closed lines. Typically, it is increased by a factor of ∼2, which is consistent with the intermittent pulsars’ spin-down behavior during the “off” and “on” states. We find that there is a threshold of maximal twist angle {{Δ }}{φ }{{thres}}∼ 1. The magnetosphere is stable only if the closed line twist angle is less than {{Δ }}{φ }{{thres}}. Beyond this value, the magnetosphere becomes unstable and gets untwisted. The spin-down rate would reduce to its off-state value. The quasi-periodicity in spin-down rate change can be explained by long-term activities in the star’s crust and the untwisting induced by MHD instability. The estimated duration of on-state is about 1 week, consistent with observations. Due to the MHD instability, there exists an upper limit for the spin-down ratio (f∼ 3) between the on-state and the off-state, if the Y-point remains at the light cylinder.

  5. Turbulent Fluctuations in the Magnetosheath and Magnetospheric Dynamics

    NASA Astrophysics Data System (ADS)

    Antonova, Elizaveta; Ovchinnikov, Ilya; Stepanova, Marina; Znatkova, Svetlana; Kirpichev, Igor; Pulinets, Maria

    2016-07-01

    One of the main problems of the magnetospheric dynamics is its rather limited predictability based on only solar wind and interplanetary magnetic field (IMF) parameters. This is connected as with the comparatively high level of the inner magnetospheric turbulence as with the great variability of the conditions at the magnetospheric boundary. The outer baundary conditions, which determine the magnetospheric dynamics, are formed in the magnetosheath near the magnetopause. The main property of the Earth's magnetosheath is a very high level of observed fluctuations of plasma and magnetic field parameters. These fluctuations are much larger than solar wind fluctuations. We argue that the comparatively low correlation of interplanetary magnetic field and magnetic field before the magnetopause can explane comparatively low correlation coefficients of geomagnetic indaxes with the solar wind and IMF parameters. One of the main difficulty of the analysis of magnetosheath properties is connected with using the frozen-in approximation. We analyze the applicability of such approximation taking into account the existence of high level of turbulence in the magnetosheath including electrostatic fluctuations. We show that the high level of turbulence creates the real difficulty for the suggestion of the validity of the frozen in condition. We analyze the condition of pressure balance at the magnetopause as the main condition determining the magnetosheath plasma penetration inside the magnetosphere and discuss its role in the formation of geomagnetic activity.

  6. Solar wind driving of asymmetries in the magnetosheath - magnetosphere system

    NASA Astrophysics Data System (ADS)

    Dimmock, Andrew; Pulkkinen, Tuija; Osmane, Adnane; Nykyri, Katariina

    2015-04-01

    Over the decades of in-situ measurements of the terrestrial magnetosphere it has been suggested and experimentally shown that various parameter dawn-dusk asymmetries arise. What is also apparent is that such asymmetries are delicately coupled to the properties of the solar wind. The IMF configuration has a considerable impact since its orientation dictates the shock geometry, thus driving different dawn-dusk plasma properties downstream. Magnetosheath asymmetries are notably important since the magnetosheath effectively modifies and reconfigures plasma before it enters the inner magnetosphere and therefore may play a role in driving asymmetries in the inner magnetosphere. We apply our existing statistical mapping tool which uses over 7 years of THEMIS and OMNI data to create statistical maps of plasma properties in the global magnetospheric system. We look at asymmetries of both steady state properties (e.g. B, V, n), and also transient/kinetic features such as mirror mode activity. We focus specifically on 1. solar wind dependence and 2. the co-dependence between the magnetosheath and magnetospheric regions.

  7. Twist-induced Magnetosphere Reconfiguration for Intermittent Pulsars

    NASA Astrophysics Data System (ADS)

    Huang, Lei; Yu, Cong; Tong, Hao

    2016-08-01

    We propose that the magnetosphere reconfiguration induced by magnetic twists in the closed field line region can account for the mode switching of intermittent pulsars. We carefully investigate the properties of axisymmetric force-free pulsar magnetospheres with magnetic twists in closed field line regions around the polar caps. The magnetosphere with twisted closed lines leads to enhanced spin-down rates. The enhancement in spin-down rate depends on the size of the region with twisted closed lines. Typically, it is increased by a factor of ˜2, which is consistent with the intermittent pulsars’ spin-down behavior during the “off” and “on” states. We find that there is a threshold of maximal twist angle {{Δ }}{φ }{{thres}}˜ 1. The magnetosphere is stable only if the closed line twist angle is less than {{Δ }}{φ }{{thres}}. Beyond this value, the magnetosphere becomes unstable and gets untwisted. The spin-down rate would reduce to its off-state value. The quasi-periodicity in spin-down rate change can be explained by long-term activities in the star’s crust and the untwisting induced by MHD instability. The estimated duration of on-state is about 1 week, consistent with observations. Due to the MHD instability, there exists an upper limit for the spin-down ratio (f˜ 3) between the on-state and the off-state, if the Y-point remains at the light cylinder.

  8. The inner magnetosphere ion composition and local time distribution over a solar cycle

    NASA Astrophysics Data System (ADS)

    Kistler, L. M.; Mouikis, C. G.

    2016-03-01

    Using the Cluster/Composition and Distribution Function (CODIF) analyzer data set from 2001 to 2013, a full solar cycle, we determine the ion distributions for H+, He+, and O+ in the inner magnetosphere (L < 12) over the energy range 40 eV to 40 keV as a function magnetic local time, solar EUV (F10.7), and geomagnetic activity (Kp). Concentrating on L = 6-7 for comparison with previous studies at geosynchronous orbit, we determine both the average flux at 90° pitch angle and the pitch angle anisotropy as a function of energy and magnetic local time. We clearly see the minimum in the H+ spectrum that results from the competition between eastward and westward drifts. The feature is weaker in O+ and He+, leading to higher O+/H+ and He+/H+ ratios in the affected region, and also to a higher pitch angle anisotropy, both features expected from the long-term effects of charge exchange. We also determine how the nightside L = 6-7 densities and temperatures vary with geomagnetic activity (Kp) and solar EUV (F10.7). Consistent with other studies, we find that the O+ density and relative abundance increase significantly with both Kp and F10.7. He+ density increases with F10.7, but not significantly with Kp. The temperatures of all species decrease with increasing F10.7. The O+ and He+ densities increase from L = 12 to L ~ 3-4, both absolutely and relative to H+, and then drop off sharply. The results give a comprehensive view of the inner magnetosphere using a contiguous long-term data set that supports much of the earlier work from GEOS, ISEE, Active Magnetospheric Particle Tracer Explorers, and Polar from previous solar cycles.

  9. Tracking the energy input form the magnetosphere to the ionosphere-thermosphere system

    NASA Astrophysics Data System (ADS)

    Zesta, E.; Connor, H.; Shi, Y.; Raeder, J.; Fedrizzi, M.; Fuller-Rowell, T. J.; Codrescu, M.

    2014-12-01

    During geomagnetically active times, the ionosphere - thermosphere (IT) system is strongly affected by magnetospheric energy that comes in the form of auroral particle precipitation and Poynting flux. This ultimately results in the increase of the thermospheric mass density, a critical parameter not only for determining and predicting air drag on satellites, but also for understanding the solar wind - magnetosphere- IT coupling. We use observations and model simulations to explore when, where and how energy transfers from the solar wind through the magnetosphere and is deposited into the IT system during solar wind disturbances. We observe and simulate dynamic pressure impacts on the magnetosphere and a magnetic storm main phase. We use thermospheric density observations from the CHAMP and GRACE satellites and Poynting flux measurements from Defense Meteorological Satellite Platform (DMSP) satellites. We show that the thermosphere density as well as the downward Poynting flux intensified shortly after (within ~20 min) the sudden enhancement of the solar wind dynamic pressure mostly in the dayside auroral zone and polar cap regions with the peaks in the vicinity of the cusp. Simulations from the two-way coupled OpenGGCM-CTIM magnetosphere-ionosphere-thermosphere model show that the ionospheric Joule heating also increases abruptly along with the sudden enhancement of the dynamic pressure in the same regions. The modeling results show that the pair of high-latitude localized cusp field-aligned currents (FACs) are intensified and extended azimuthally as a result of the enhanced dayside high-latitude reconnection caused by the sudden increase of the solar wind dynamic pressure. They are likely the source of the enhanced Joule heating and the ensuing thermospheric heating in that region. We also look at the first hours of a magnetic storm main phase where the picture is significantly more complex, but Poynting flux and thermospheric density first enhance at polar

  10. Magnetosphere-ionosphere interactions: Near Earth manifestations of the plasma universe

    NASA Technical Reports Server (NTRS)

    Faelthammar, Carl-Gunne

    1986-01-01

    As the universe consists almost entirely of plasma, the understanding of astrophysical phenomena must depend critically on the understanding of how matter behaves in the plasma state. In situ observations in the near Earth cosmical plasma offer an excellent opportunity of gaining such understanding. The near Earth cosmical plasma not only covers vast ranges of density and temperature, but is the site of a rich variety of complex plasma physical processes which are activated as a results of the interactions between the magnetosphere and the ionosphere. The geomagnetic field connects the ionosphere, tied by friction to the Earth, and the magnetosphere, dynamically coupled to the solar wind. This causes an exchange of energy an momentum between the two regions. The exchange is executed by magnetic-field-aligned electric currents, the so-called Birkeland currents. Both directly and indirectly (through instabilities and particle acceleration) these also lead to an exchange of plasma, which is selective and therefore causes chemical separation. Another essential aspect of the coupling is the role of electric fields, especially magnetic field aligned (parallel) electric fields, which have important consequences both for the dynamics of the coupling and, especially, for energization of charged particles.

  11. Kinetic models for space weather: from the solar wind to the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Pierrard, Viviane; Moschou, Sofia; Lopez Rosson, Graciela; Borremans, Kris

    2016-04-01

    Kinetic models for the solar wind and different regions of the inner magnetosphere have been developed at IASB-BIRA. The velocity distribution functions (VDF) of the particles are determined by solving the evolution equation. The moments are obtained by integration of the velocity distribution function on the velocity space. An exospheric model of the solar wind assuming a kappa VDF for the electrons has been developed in three dimensions for predictions at 1 AU. Photospheric magnetograms serve as observationally driven input and semi-empirical coronal models are used for the estimation of the plasma characteristics at the lower heliospheric distances to obtain the best comparison with available observations at the Earth's orbit. A 3D dynamic model of the plasmasphere has also been developed on similar kinetic assumptions and provides the position of the plasmapause, the number density and the temperature of the electrons and protons in the ionosphere as well as inside and outside the plasmasphere. During geomagnetic storms driven by solar wind parameters, the plasmasphere is eroded and structures like plasmaspheric plumes and shoulders can appear. The radiation belts as observed with the Energetic Particle Telescope on board the PROBA-V satellite are also very dynamic during geomagnetic storms and show some links with the plasmapause positions just after the storms. The year 2015 was very active and was especially instructive for studies of the dynamic properties in the inner magnetosphere during geomagnetic storms.

  12. Mucosal and systemic adjuvant activity of alphavirus replicon particles

    NASA Astrophysics Data System (ADS)

    Thompson, Joseph M.; Whitmore, Alan C.; Konopka, Jennifer L.; Collier, Martha L.; Richmond, Erin M. B.; Davis, Nancy L.; Staats, Herman F.; Johnston, Robert E.

    2006-03-01

    Vaccination represents the most effective control measure in the fight against infectious diseases. Local mucosal immune responses are critical for protection from, and resolution of, infection by numerous mucosal pathogens. Antigen processing across mucosal surfaces is the natural route by which mucosal immunity is generated, as peripheral antigen delivery typically fails to induce mucosal immune responses. However, we demonstrate in this article that mucosal immune responses are evident at multiple mucosal surfaces after parenteral delivery of Venezuelan equine encephalitis virus replicon particles (VRP). Moreover, coinoculation of null VRP (not expressing any transgene) with inactivated influenza virions, or ovalbumin, resulted in a significant increase in antigen-specific systemic IgG and fecal IgA antibodies, compared with antigen alone. Pretreatment of VRP with UV light largely abrogated this adjuvant effect. These results demonstrate that alphavirus replicon particles possess intrinsic systemic and mucosal adjuvant activity and suggest that VRP RNA replication is the trigger for this activity. We feel that these observations and the continued experimentation they stimulate will ultimately define the specific components of an alternative pathway for the induction of mucosal immunity, and if the activity is evident in humans, will enable new possibilities for safe and inexpensive subunit and inactivated vaccines. vaccine vector | Venezuelan equine encephalitis virus | viral immunology | RNA virus

  13. Plasma instabilities in the terrestrial magnetosphere - A review of recent theoretical research

    NASA Technical Reports Server (NTRS)

    Gary, S. Peter

    1987-01-01

    This paper reviews recent theoretical research on plasma instabilities in the terrestrial magnetosphere. This paper is organized with respect to particle free energies: electron-ion currents, electron beams, ion beams, electron anisotropies and ion anisotropies are successively considered. For each free energy, the associated instability properties are summarized, and their applications to magnetospheric physics are briefly described. Theory and simulations which have established close correlations with observations are emphasized.

  14. Chorus wave amplification: A free electron laser in the Earth's magnetosphere

    SciTech Connect

    Soto-Chavez, A. R.; Bhattacharjee, A.; Ng, C. S.

    2012-01-15

    A new theoretical model for whistler-mode chorus amplification in the Earth's magnetosphere is presented. We derive, based on the free-electron laser mechanism in a high-gain amplifier, a new closed set of self-consistent relativistic equations that couple the Hamiltonian equations for particles with Maxwell's equations. We demonstrate that these equations predict, through a cubic equation, whistler amplification levels in good agreement with those observed in the Earth's magnetosphere.

  15. Energetic Electron Populations in the Magnetosphere During Geomagnetic Storms and Substorms

    NASA Technical Reports Server (NTRS)

    McKenzie, David L.; Anderson, Phillip C.

    2002-01-01

    This report summarizes the scientific work performed by the Aerospace Corporation under NASA Grant NAG5-10278, 'Energetic Electron Populations in the Magnetosphere during Geomagnetic Storms and Subsisting.' The period of performance for the Grant was March 1, 2001 to February 28, 2002. The following is a summary of the Statement of Work for this Grant. Use data from the PIXIE instrument on the Polar spacecraft from September 1998 onward to derive the statistical relationship between particle precipitation patterns and various geomagnetic activity indices. We are particularly interested in the occurrence of substorms during storm main phase and the efficacy of storms and substorms in injecting ring-current particles. We will compare stormtime simulations of the diffuse aurora using the models of Chen and Schulz with stormtime PIXIE measurements.

  16. Cross-Scale Coupling in the Inner Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Galagher, D.; Spann, J.; Singh, N.

    2004-01-01

    Magnetosphere-ionosphere (MI) coupling has interested scientists for decades and, in spite of experimental and theoretical research efforts, is still one of the least well-known dynamic processes in space plasma. The reason for this is that the numerous physical processes associated with MI coupling occur over multiple spatial lengths and temporal scales. One typical example of MI coupling is small- and large-scale ring current (RC) electrodynamic coupling. In this talk, we will address the two primary issues of RC electrodynamic coupling: (1) RC self-consistent coupling with electromagnetic ion cyclotron (EMIC) waves (small-scale electrodynamic coupling) and (2) RC self-consistent MI coupling that includes calculation of the magnetospheric electric field (large-scale electrodynamic coupling). We also will emphasize the role of the heavy ions in the number of wave-particle interaction magnetospheric processes. In particular, we will discuss some of the experimental and theoretical studies that have investigated the role of the heavy ions (mainly He(+) and O(+)) in generation and propagation of electromagnetic ion cyclotron waves and their contribution to the heating of magnetospheric electrons and ions. The more recent studies have also shown that the heavy ions can greatly contribute to a generation of lower hybrid waves, ring current precipitation phenomena, and the overall energy redistribution in the inner magnetosphere. Using newly developed 2.5-dimensional particle-in-cell simulations, we study the energization and nonlinear coupling of different plasma waves in the presence of the heavy ions. We have shown that the high frequency wave modes critically depend on the heavy ion density and irrespective of the driven wave modes, both the light and heavy ions undergo significant transverse acceleration. But for the large heavy-ion densities, even the electrons are significantly accelerated in the parallel direction by the waves below the LH frequency.

  17. Morphology of Interchange-Driven Injections in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Paranicas, C.; Achilleos, N.; Andriopoulou, M.; Badman, S. V.; Hospodarsky, G. B.; Jia, X.; Jackman, C. M.; Khurana, K. K.; Krupp, N.; Louarn, P.; Roussos, E.; Sergis, N.; Thomsen, M. F.

    2014-12-01

    As Cassini passes close to Saturn during its regular orbits, evidence of particle injections can often be found in many different data sets (including MAG, CAPS, MIMI, and RPWS). One reason injections are easily visible in Saturn's inner magnetosphere is that the circumplanetary neutral gas distribution can reduce the intensities of some charged particles. For example, energetic ions can be lost from the system following charge exchange with neutrals and energetic electrons can lose energy in collisions with gas and dust. Injections in the inner magnetosphere are believed to be flux tube interchange events that are part of a larger circulation system in which cold dense plasma flows outward carrying magnetic flux with it. The closed magnetic flux is ultimately returned to the inner magnetosphere in the form of injections of rapidly moving hotter but lighter flux tubes from the middle magnetosphere. In this presentation, we will look at injections from the perspective of multiple Cassini data sets. Some features of these structures have already been identified in the literature from one or more data sets. For example, the tendency for injections to appear as enhancements (depressions) in magnetic field strength at low (high) magnetic latitude has been documented (Andre et al. 2007). Furthermore, that flux tube bundles seem to narrow in spatial extent in the equatorial plane in the higher magnetic field region has also been described. Here, we will look at selected structures distributed in radial distance and latitude as a step toward generalizing their characteristics at various locations. We will consider issues such as the magnetic signature in the field components, the typical wave signatures, the energy range of the injection, and the presence of isolated features versus multiple features occurring simultaneously. We will also discuss observational issues, such as when each instrument is optimally suited to detect injections, and how this relates to their

  18. Fluctuating magnetic fields in the magnetosphere. II - ULF waves.

    NASA Technical Reports Server (NTRS)

    Mcpherron, R. L.; Russell, C. T.; Coleman, P. J., Jr.

    1972-01-01

    At the present time the existing satellite observations of ULF waves suggest that the level of geomagnetic activity controls the types of waves which occur within the magnetosphere. Consequently, we consider separately quiet times, times of magnetospheric substorms, and times of magnetic storms. Within each of these categories, there are distinctly different wave modes distinguished by their polarization: either transverse or parallel to the ambient field. In addition, these wave phenomena occur in distinct frequency bands. In terms of the standard nomenclature of ground micropulsation studies ULF wave types observed in the magnetosphere include quiet time transverse - Pc 1, Pc 3, Pc 4, Pc 5; quiet time compressional - Pc 1 and Pi 1; substorm compressional Pi 1 and Pi 2; storm transverse - Pc 1; storm compressional Pc 4, 5.

  19. Wave emissions from planetary magnetospheres

    NASA Technical Reports Server (NTRS)

    Grabbe, Crockett L.

    1989-01-01

    An important development in the Earth magnetosphere was the discovery of the boundary of the plasma sheet and its apparent role in the dynamics of the magnetotails. Three instabilities (negative energy mode, counterstreaming, and the Buneman instability) were investigated through analytical and numerical studies of their frequency and growth rate as a function of the angle of propagation.

  20. Ion trajectories in Mercury's magnetosphere

    NASA Astrophysics Data System (ADS)

    Sarantos, M.; Reiff, P.; Killen, R.

    2003-04-01

    The atmosphere of Mercury is eroded quickly by photoionization and electron impact ionization. Resulting ions are affected by both magnetic and electric field forces due to their small energy. The escape flux of these ions from Mercury's magnetosphere is believed to respond to the degree of solar wind - Hermean magnetosphere interaction. We present the structure of the Hermean magnetosphere obtained by the Toffoletto-Hill (JGR 98, 1339, 1993) model of an open magnetosphere, and supplement it with the Ding et al. (Phys. Space Plasmas, 1996) potential solver to represent the convection electric field. We follow thousands of Na and K ions in a tight grid of magnetic and electric fields at Mercury. Ions are created with a spatial distribution given from the neutral distribution to cover the entire dayside, and are launched at the surface, with an isotropic angular distribution. The initial energy is taken to be ˜1eV. We calculate the loci of points where the ions reimpact the planetary surface. We conclude that the dawn-dusk asymmetry and high-latitude enhancements in the sodium atmosphere are perpetuated by the pattern of ion redistribution due to a predominant dawn to dusk electric field. The solar wind ion sputtering effect will further amplify atmospheric patchiness.