Magnetospheric and auroral plasmas - A short survey of progress

NASA Technical Reports Server (NTRS)

Frank, L. A.

1975-01-01

Important milestones in our researches of auroral and magnetospheric plasmas for the past quadrennium 1971-1975 are reviewed. Many exciting findings, including those of the polar cusp, the polar wind, the explosive disruptions of the magnetotail, the interactions of hot plasmas with the plasmapause, the auroral field-aligned currents, and the striking inverted V electron precipitation events, were reported during this period. Solutions to major questions concerning the origins and acceleration of these plasmas appear possible in the near future. A comprehensive bibliography of current research is appended to this brief survey of auroral and magnetospheric plasmas.

MHD Simulations of Magnetospheric Accretion, Ejection and Plasma-field Interaction

NASA Astrophysics Data System (ADS)

Romanova, M. M.; Lovelace, R. V. E.; Bachetti, M.; Blinova, A. A.; Koldoba, A. V.; Kurosawa, R.; Lii, P. S.; Ustyugova, G. V.

2014-01-01

We review recent axisymmetric and three-dimensional (3D) magnetohydrodynamic (MHD) numerical simulations of magnetospheric accretion, plasma-field interaction and outflows from the disk-magnetosphere boundary.

Imaging of laboratory magnetospheric plasmas using coherence imaging technique

NASA Astrophysics Data System (ADS)

Nishiura, Masaki; Takahashi, Noriki; Yoshida, Zensho; Nakamura, Kaori; Kawazura, Yohei; Kenmochi, Naoki; Nakatsuka, Masataka; Sugata, Tetsuya; Katsura, Shotaro; Howard, John

2017-10-01

The ring trap 1 (RT-1) device creates a laboratory magnetosphere for the studies on plasma physics and advanced nuclear fusion. A levitated superconducting coil produces magnetic dipole fields that realize a high beta plasma confinement that is motivated by self-organized plasmas in planetary magnetospheres. The electron cyclotron resonance heating (ECRH) with 8.2 GHz and 50 kW produces the plasmas with hot electrons in a few ten keV range. The electrons contribute to the local electron beta that exceeded 1 in RT-1. For the ion heating, ion cyclotron range of frequencies (ICRF) heating with 2-4 MHz and 10 kW has been performed in RT-1. The radial profile of ion temperature by a spectroscopic measurement indicates the signature of ion heating. In the holistic point of view, a coherence imaging system has been implemented for imaging the entire ion dynamics in the laboratory magnetosphere. The diagnostic system and obtained results will be presented.

Modeling the Enceladus Plasma and Neutral Torus in Saturn's Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Jia, Yingdong; Russell, C. T.; Khurana, K. K.; Gombosi, T. I.

2010-10-01

Saturn's moon Enceladus, produces hundreds of kilograms of water vapor every second. These water molecules form a neutral torus which is comparable to the Io torus in the Jovian system. These molecules become ionized producing a plasma disk in the inner magnetosphere of Saturn which exchanges momentum with the "corotating” magnetospheric plasma. To balance the centripetal force of this plasma disk, Saturn's magnetic field is stretched in the radial direction and to accelerate the azimuthal speed to corotational values, the field is stretched in the azimuthal direction. At Enceladus the massive pickup of new ions from its plume slows down the corotating flow and breaks this force balance, causing plasma flows in the radial direction. Such radial flows in the inner magnetosphere of Saturn are supported by Cassini observations using various particle and field instruments. In this study we develop a global model of the inner magnetosphere of Saturn in an attempt to reproduce such processes.

Plasma Drifts in the Intermediate Magnetosphere: Simulation Results

NASA Astrophysics Data System (ADS)

Lyon, J.; Zhang, B.

2016-12-01

One of the outstanding questions about the inner magnetosphere dynamics is how the ring current is populated. It is not clear how much is due to a general injection over longer time and spatial scales and how much due to more bursty events. One of the major uncertainties is the behavior of the plasma in the intermediate magnetosphere: the region where the magnetosphere changes from being tail-like to one where the dipole field dominates. This is also the region where physically the plasma behavior changes from MHD-like in the tail to one dominated by particle drifts in the inner magnetosphere. No of the current simulation models self-consistently handle the region where drifts are important but not dominant. We have recently developed a version of the multi-fluid LFM code that can self-consistently handle this situation. The drifts are modeled in a fashion similar to the Rice Convection Model in that a number of energy "channels" are explicitly simulated. However, the method is not limited to the "slow flow" region and both diamagnetic and inertial drifts are included. We present results from a number of idealized cases of the global magnetosphere interacting with a southward turning of the IMF. We discuss the relative importance of general convection and bursty flows to the transport of particles and energy across this region.

The Magnetospheric Multiscale Mission...Resolving Fundamental Processes in Space Plasmas

NASA Technical Reports Server (NTRS)

Curtis, S.

1999-01-01

The Magnetospheric Multiscale (MMS) mission is a multiple-spacecraft Solar-Terrestrial Probe designed to study the microphysics of magnetic reconnection, charged particle acceleration, and turbulence in key boundary regions of Earth's magnetosphere. These three processes, which control the flow of energy, mass, and momentum within and across plasma boundaries, occur throughout the universe and are fundamental to our understanding of astrophysical and solar system plasmas. Only in Earth's magnetosphere, however, are they readily accessible for sustained study through in-situ measurement. MMS will employ five co-orbiting spacecraft identically instrumented to measure electric and magnetic fields, plasmas, and energetic particles. The initial parameters of the individual spacecraft orbits will be designed so that the spacecraft formation will evolve into a three-dimensional configuration near apogee, allowing MMS to differentiate between spatial and temporal effects and to determine the three dimensional geometry of plasma, field, and current structures. In order to sample all of the magnetospheric boundary regions, MMS will employ a unique four-phase orbital strategy involving carefully sequenced changes in the local time and radial distance of apogee and, in the third phase, a change in orbit inclination from 10 degrees to 90 degrees. The nominal mission operational lifetime is two years. Launch is currently scheduled for 2006.

Penetration of Magnetosheath Plasma into Dayside Magnetosphere: 1. Density, Velocity, and Rotation

NASA Technical Reports Server (NTRS)

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

2016-01-01

In this study, we examine a large number of plasma structures (filaments), observed with the Cluster spacecraft during 2 years (2007-2008) in the dayside magnetosphere but consisting of magnetosheath plasma. To reduce the effects observed in the cusp regions and on magnetosphere flanks, we consider these events predominantly inside the narrow cone less than 30 about the subsolar point. Two important features of these filaments are (i) their stable antisunward (earthward) motion inside the magnetosphere, whereas the ambient magnetospheric plasma moves usually in the opposite direction (sunward), and (ii) between these filaments and the magnetopause, there is a region of magnetospheric plasma, which separates these filaments from the magnetosheath. The stable earthward motion of these magnetopause show the possible disconnection of these filaments from the magnetosheath, as suggested earlier by many researchers. The results also show that these events cannot be a result of back-and-forth motions of magnetopause position or surface waves propagating on the magnetopause. Another important feature of these filaments is their rotation about the filament axis, which might be a result of their passage through the velocity shear on magnetopause boundary. After crossing the velocity shear, the filaments get a rotational velocity, which has opposite directions in the noon-dusk and noon-dawn sectors. This rotation velocity may be an important factor, supporting the stability of these filaments and providing their motion into the magnetosphere.

Saturn's Magnetospheric Plasma Flow Encountered by Titan

NASA Astrophysics Data System (ADS)

Sillanpää, I.

2017-09-01

Titan has been a major target of the ending Cassini mission to Saturn. 126 flybys have sampled, measured and observed a variety of Titan's features and processes from the surface features to atmospheric composition and upper atmospheric processes. Titan's interaction with the magnetospheric plasma flow it is mostly embedded in is highly dependent on the characteristics of the ambient plasma. The density, velocity and even the composition of the plasma flow can have great variance from flyby to flyby. Our purpose is the present the plasma flow conditions for all over 70 flybys of which we have Cassini Plasma Spectrometer (CAPS) measurements.

Modeling of the Convection and Interaction of Ring Current, Plasmaspheric and Plasma Sheet Plasmas in the Inner Magnetosphere

NASA Technical Reports Server (NTRS)

Fok, Mei-Ching; Chen, Sheng-Hsien; Buzulukova, Natalia; Glocer, Alex

2010-01-01

Distinctive sources of ions reside in the plasmasphere, plasmasheet, and ring current regions at discrete energies constitute the major plasma populations in the inner/middle magnetosphere. They contribute to the electrodynamics of the ionosphere-magnetosphere system as important carriers of the global current system, in triggering; geomagnetic storm and substorms, as well as critical components of plasma instabilities such as reconnection and Kelvin-Helmholtz instability at the magnetospheric boundaries. Our preliminary analysis of in-situ measurements shoves the complexity of the plasmas pitch angle distributions at particularly the cold and warm plasmas, vary dramatically at different local times and radial distances from the Earth in response to changes in solar wind condition and Dst index. Using an MHD-ring current coupled code, we model the convection and interaction of cold, warm and energetic ions of plasmaspheric, plasmasheet, and ring current origins in the inner magnetosphere. We compare our simulation results with in-situ and remotely sensed measurements from recent instrumentation on Geotail, Cluster, THEMIS, and TWINS spacecraft.

Self-Consistent Magnetosphere-Ionosphere Coupling and Associated Plasma Energization Processes

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Six, N. Frank (Technical Monitor)

2002-01-01

Magnetosphere-Ionosphere (MI) coupling and associated with this process electron and ion energization processes have interested scientists for decades and, in spite of experimental and theoretical research efforts, are still ones of the least well known dynamic processes in space plasma physics. 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 large scale ring current (RC) electrodynamic coupling that includes calculation of the magnetospheric electric field that is consistent with the ring current (RC) distribution. A general scheme for numerical simulation of such large-scale magnetosphere-ionosphere coupling processes has been presented earlier in many works. The mathematical formulation of these models are based on "modified frozen-in flux theorem" for an ensemble of adiabatically drifting particles in the magnetosphere. By tracking the flow of particles through the inner magnetosphere, the bounce-averaged phase space density of the hot ions and electrons can be reconstructed and the magnetospheric electric field can be calculated such that it is consistent with the particle distribution in the magnetosphere. The new a self-consistent ring current model has been developed that couples electron and ion magnetospheric dynamics with calculation of electric field. Two new features were taken into account in addition to the RC ions, we solve an electron kinetic equation in our model, self-consistently including these results in the solution. Second, using different analytical relationships, we calculate the height integrated ionospheric conductances as the function of precipitated high energy magnetospheric electrons and ions as produced by our model. This results in fundamental changes to the electric potential pattern in the inner magnetosphere, with a smaller Alfven boundary than previous potential formulations would predict but

Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results

NASA Technical Reports Server (NTRS)

Ober, Daniel M.; Horwitz, J. L.

1998-01-01

We present initial results on the modeling of the circulation of plasmaspheric-origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X= -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

Fast Plasma Investigation for Magnetospheric Multiscale

NASA Technical Reports Server (NTRS)

Pollock, C.; Moore, T.; Coffey, V.; Dorelli J.; Giles, B.; Adrian, M.; Chandler, M.; Duncan, C.; Figueroa-Vinas, A.; Garcia, K.;

The role of plasma/neutral source and loss processes in shaping the giant planet magnetospheres

NASA Astrophysics Data System (ADS)

Delamere, P. A.

2014-12-01

The giant planet magnetospheres are filled with neutral and ionized gases originating from satellites orbiting deep within the magnetosphere. The complex chemical and physical pathways for the flow of mass and energy in this partially ionized plasma environment is critical for understanding magnetospheric dynamics. The flow of mass at Jupiter and Saturn begins, primarily, with neutral gases emanating from Io (~1000 kg/s) and Enceladus (~200 kg/s). In addition to ionization losses, the neutral gases are absorbed by the planet, its rings, or escape at high speeds from the magnetosphere via charge exchange reactions. The net result is a centrifugally confined torus of plasma that is transported radially outward, distorting the magnetic field into a magnetodisc configuration. Ultimately the plasma is lost to the solar wind. A critical parameter for shaping the magnetodisc and determining its dynamics is the radial plasma mass transport rate (~500 kg/s and ~50 kg/s for Jupiter and Saturn respectively). Given the plasma transport rates, several simple properties of the giant magnetodiscs can be estimated including the physical scale of the magnetosphere, the magnetic flux transport, and the magnitude of azimuthal magnetic field bendback. We will discuss transport-related magnetic flux conservation and the mystery of plasma heating—two critical issues for shaping the giant planet magnetospheres.

Rate of radial transport of plasma in Saturn’s inner magnetosphere

NASA Astrophysics Data System (ADS)

Chen, Y.; Hill, T. W.

2009-12-01

The Cassini Plasma Spectrometer (CAPS) and the Cassini Magnetospheric Imaging Instrument (MIMI) frequently observe longitudinally localized injection and drift dispersion of hot plasma in Saturn’s magnetosphere. These signatures provide direct evidence for the major convective process in the inner magnetosphere of a rapidly rotating planet, in which the radial transport of plasma comprises hot, tenuous plasma moving inward and cooler, denser plasma moving outward. These injection events have been found to occupy only a small fraction of the total available longitudinal space, indicating that the inflow speed is probably much larger than the outflow speed. We set the local corotation speed as the upper limit of inflow velocities, and deduce the corresponding radial velocities of the outflowing flux tubes by analyzing the width of injection structures and assuming that the total potential drop around a given L-shell is zero. We then estimate an upper limit to the plasma outward mass transport rate, which turns out to be somewhat larger than previous estimates of the Enceladus source rate (e.g., Pontius and Hill, 2006). An important assumption in this study is that the plasma is largely confined to a thin equatorial sheet, and we have applied a centrifugal scale height model developed by Hill and Michel [1976].

Plasma Sheet Injections into the Inner Magnetosphere: Two-way Coupled OpenGGCM-RCM model results

NASA Astrophysics Data System (ADS)

Raeder, J.; Cramer, W. D.; Toffoletto, F.; Gilson, M. L.; Hu, B.

2017-12-01

Plasma sheet injections associated with low flux tube entropy bubbles have been found to be the primary means of mass transport from the plasma sheet to the inner magnetosphere. A two-way coupled global magnetosphere-ring current model, where the magnetosphere is modeled by the OpenGGCM MHD model and the ring current is modeled by the Rice Convection Model (RCM), is used to determine the frequency of association of bubbles with injections and inward plasma transport, as well as typical injection characteristics. Multiple geomagnetic storms and quiet periods are simulated to track and characterize inward flow behavior. Dependence on geomagnetic activity levels or drivers is also examined.

The design and development of a space laboratory to conduct magnetospheric and plasma research

NASA Technical Reports Server (NTRS)

Rosen, A.

1974-01-01

A design study was conducted concerning a proposed shuttle-borne space laboratory for research on magnetospheric and plasma physics. A worldwide survey found two broad research disciplines of interest: geophysical studies of the dynamics and structure of the magnetosphere (including wave characteristics, wave-particle interactions, magnetospheric modifications, beam-plasma interactions, and energetic particles and tracers) and plasma physics studies (plasma physics in space, wake and sheath studies, and propulsion and devices). The Plasma Physics and Environmental Perturbation Laboratory (PPEPL) designed to perform experiments in these areas will include two 50-m booms and two maneuverable subsatellites, a photometer array, standardized proton, electron, and plasma accelerators, a high-powered transmitter for frequencies above 100 kHz, a low-power transmitter for VLF and below, and complete diagnostic packages. Problem areas in the design of a space plasma physics laboratory are indicated.

The Warm Plasma Composition in the Inner Magnetosphere during 2012–2015

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jahn, J. M.; Goldstein, J.; Reeves, Geoffrey D.

Ionospheric heavy ions play an important role in the dynamics of Earth's magnetosphere. The greater mass and gyro radius of ionospheric oxygen differentiates its behavior from protons at the same energies. Oxygen may have an impact on tail reconnection processes, and it can at least temporarily dominate the energy content of the ring current during geomagnetic storms. At sub-keV energies, multi-species ion populations in the inner magnetosphere form the warm plasma cloak, occupying the energy range between the plasmasphere and the ring current. Lastly, cold lighter ions from the mid-latitude ionosphere create the co-rotating plasmasphere whose outer regions can interactmore » with the plasma cloak, plasma sheet, ring current, and outer electron belt. Here in this paper we present a statistical view of warm, cloak-like ion populations in the inner magnetosphere, contrasting in particular the warm plasma composition during quiet and active times. We study the relative abundances and absolute densities of warm plasma measured by the Van Allen Probes, whose two spacecraft cover the inner magnetosphere from plasmaspheric altitudes close to Earth to just inside geostationary orbit. We observe that warm (>30 eV) oxygen is most abundant closer to the plasmasphere boundary whereas warm hydrogen dominates closer to geostationary orbit. Warm helium is usually a minor constituent, but shows a noticeable enhancement in the near-Earth dusk sector.« less

The Warm Plasma Composition in the Inner Magnetosphere during 2012–2015

DOE PAGES

Jahn, J. M.; Goldstein, J.; Reeves, Geoffrey D.; ...

2017-09-11

Ionospheric heavy ions play an important role in the dynamics of Earth's magnetosphere. The greater mass and gyro radius of ionospheric oxygen differentiates its behavior from protons at the same energies. Oxygen may have an impact on tail reconnection processes, and it can at least temporarily dominate the energy content of the ring current during geomagnetic storms. At sub-keV energies, multi-species ion populations in the inner magnetosphere form the warm plasma cloak, occupying the energy range between the plasmasphere and the ring current. Lastly, cold lighter ions from the mid-latitude ionosphere create the co-rotating plasmasphere whose outer regions can interactmore » with the plasma cloak, plasma sheet, ring current, and outer electron belt. Here in this paper we present a statistical view of warm, cloak-like ion populations in the inner magnetosphere, contrasting in particular the warm plasma composition during quiet and active times. We study the relative abundances and absolute densities of warm plasma measured by the Van Allen Probes, whose two spacecraft cover the inner magnetosphere from plasmaspheric altitudes close to Earth to just inside geostationary orbit. We observe that warm (>30 eV) oxygen is most abundant closer to the plasmasphere boundary whereas warm hydrogen dominates closer to geostationary orbit. Warm helium is usually a minor constituent, but shows a noticeable enhancement in the near-Earth dusk sector.« less

The kappa Distribution as Tool in Investigating Hot Plasmas in the Magnetospheres of Outer Planets

NASA Astrophysics Data System (ADS)

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

2014-12-01

The first use of a Maxwellian distribution with a high-energy tail (a κ-function) was made by Olbert (1968) and applied by Vasyliunas (1968) in analyzing electron data. The k-function combines aspects of both Maxwellian and power law forms to provide a reasonably complete description of particle density, temperature, pressure and convection velocity, all of which are key parameters of magnetospheric physics. Krimigis et al (1979) used it to describe flowing plasma ions in Jupiter's magnetosphere measured by Voyager 1, and obtained temperatures in the range of 20 to 35 keV. Sarris et al (1981) used the κ-function to describe plasmas in Earth's distant plasma sheet. The κ-function, in various formulations and names (e. g., γ-thermal distribution, Krimigis and Roelof, 1983) has been used routinely to parametrize hot, flowing plasmas in the magnetospheres of the outer planets, with typical kT ~ 10 to 50 keV. Using angular measurements, it has been possible to obtain pitch angle distributions and convective flow directions in sufficient detail for computations of temperatures and densities of hot particle pressures. These 'hot' pressures typically dominate the cold plasma pressures in the high beta (β > 1) magnetospheres of Jupiter and Saturn, but are of less importance in the relatively empty (β < 1) magnetospheres of Uranus and Neptune. Thus, the κ-function represents an effective tool in analyzing plasma behavior in planetary magnetospheres, but it is not applicable in all plasma environments. References Olbert, S., in Physics of the Magnetosphere, (Carovillano, McClay, Radoski, Eds), Springer-Verlag, New York, p. 641-659, 1968 Vasyliunas, V., J. Geophys. Res., 73(9), 2839-2884, 1968 Krimigis, S. M., et al, Science 204, 998-1003, 1979 Sarris, E., et al, Geophys. Res. Lett. 8, 349-352, 1981 Krimigis, S. M., and E. C. Roelof, Physics of the Jovian Magnetosphere, edited by A. J. Dessler, 106-156, Cambridge University Press, New York, 1983

X-ray observations from RT-1 magnetospheric plasmas

NASA Astrophysics Data System (ADS)

Sugata, Tetsuya; Masaki Nishiura Collaboration; Zensho Yoshida Collaboration; Naoki Kenmochi Collaboration; Shotaro Katsura Collaboration; Kaori Nakamura Collaboration

2017-10-01

Planetary magnetospheres like Earth and Jupiter realize stable confinement of high beta plasma. The RT-1 device produces a laboratory magnetosphere by using a levitated superconducting coil for dipole magnetic fields and 8.2 GHz electromagnetic wave for plasma production (ne 1017m-3) and electron heating. In the recent experiments, the RT-1 device has achieved the local beta that exceeds 1. It is considered that the high energy component of electrons contributes to the beta value. Therefore, Si(Li) detectors measured the X-ray spectra from the peripheral plasmas in the range from a few keV to a few ten keV. The density of a few keV component and a few ten keV component are comparable and a few ten keV component dominates the majority of the high beta value that is operated up to 0.8. We found that 150 keV component of electrons exists near the outer of the levitated dipole magnet by using a CdTe detector.

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.

Preliminary feasibility study of pallet-only mode for magnetospheric and plasmas in space payloads, volume 4

NASA Technical Reports Server (NTRS)

1976-01-01

Results of studies performed on the magnetospheric and plasma portion of the AMPS are presented. Magnetospheric and plasma in space experiments and instruments are described along with packaging (palletization) concepts. The described magnetospheric and plasma experiments were considered as separate entities. Instrumentation ospheric and plasma experiments were considered as separate entities. Instrumentation requirements and operations were formulated to provide sufficient data for unambiguous interpretation of results without relying upon other experiments of the series. Where ground observations are specified, an assumption was made that large-scale additions or modifications to existing facilities were not required.

Plasma depletions in the Jovian magnetosphere - Evidence of transport and solar wind interaction

NASA Technical Reports Server (NTRS)

Mcnutt, Ralph L., Jr.; Coppi, Paolo S.; Selesnick, Richard S.; Coppi, Bruno

1987-01-01

A series of plasma voids ('dropouts') was observed by the Plasma Science (PLS) experiment in Jupiter's magnetosphere during the Voyager 2 encounter with that planet. A reexamination of Voyager 2 data has led to the conclusion that the dropout phenomenon cannot be a manifestation of a plasma wake produced by Ganymede. Rather, the appearance of the dropouts is attributed to changes in the upstream solar wind conditions and the global state of the magnetosphere; the proximity of Voyager 2 to Ganymede at the time is considered to be coincidental. It is suggested that these dropouts are evidence of a state of 'bubbling' of the magnetosphere that alternates with 'laminar' states in which, as in the case of the Voyager 1 encounter with Jupiter, voids are not present and that these states correspond to different processes by which plasma is transported out of the system. The nature of these states is related to changes in the magnitude of the upstream solar wind ram pressure. In the bubbling state, this pressure is higher than in the laminar state and drives an intermittent instability. The analysis presented is one of the first attempts to introduce, in space physics, recently acquired theoretical notions of the physics of the finite-beta plasmas of which the Jovian magnetospheric plasma is an important example.

Transport and acceleration of plasma in the magnetospheres of Earth and Jupiter and expectations for Saturn

NASA Astrophysics Data System (ADS)

Kivelson, M. G.

The first comparative magnetospheres conference was held in Frascati, Italy thirty years ago this summer, less than half a year after the first spacecraft encounter with Jupiter's magnetosphere (Formisano, V. (Ed.), The Magnetospheres of the Earth and Jupiter, Proceedings of the Neil Brice Memorial Symposium held in Frascati, Italy, May 28-June 1, 1974. D. Reidel Publishing Co., Boston, USA, 1975). Disputes highlighted various issues still being investigated, such as how plasma transport at Jupiter deviates from the prototypical form of transport at Earth and the role of substorms in Jupiter's dynamics. Today there is a wealth of data on which to base the analysis, data gathered by seven missions that culminated with Galileo's 8-year orbital tour. We are still debating how magnetic flux is returned to the inner magnetosphere following its outward transport by iogenic plasma. We are still uncertain about the nature of sporadic dynamical disturbances at Jupiter and their relation to terrestrial substorms. At Saturn, the centrifugal stresses are not effective in distorting the magnetic field, so in some ways the magnetosphere appears Earthlike. Yet the presence of plasma sources in the close-in equatorial magnetosphere parallels conditions at Jupiter. This suggests that we need to study both Jupiter and Earth when thinking about what to anticipate from Cassini's exploration of Saturn's magnetosphere. This paper addresses issues relevant to plasma transport and acceleration in all three magnetospheres.

Magnetospheric space plasma investigations

NASA Technical Reports Server (NTRS)

Comfort, Richard H.; Horwitz, James L.

1995-01-01

Topics and investigations covering this period of this semiannual report period (August 1994 - January 1995) are as follows: (1) Generalized SemiKinetic (GSK) modeling of the synergistic interaction of transverse heating of ionospheric ions and magnetospheric plasma-driven electric potentials on the auroral plasma transport. Also, presentations of GSK modeling of auroral electron precipitation effects on ionospheric plasma outflows, of ExB effects on such outflow, and on warm plasma thermalization and other effects during refilling with pre-existing warm plasmas; (2) Referees' reports received on the statistical study of the latitudinal distributions of core plasmas along the L = 4.6 field line using DE-1/RIMS data. Other work is concerned in the same field, field-aligned flows and trapped ion distributions; and (3) A short study has been carried out on heating processes in low density flux tubes in the outer plasmasphere. The purpose was to determine whether the high ion temperatures observed in these flux tubes were due to heat sources operating through the thermal electrons or directly to the ions. Other investigations center along the same area of plasmasphere-ionosphere coupling. The empirical techniques and model, the listing of hardware calibrated, and/or tested, and a description of notable meetings attended is included in this report, along with a list of all present publication in submission or accepted and those reference papers that have resulted from this work thus far.

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.

Survey of thermal plasma ions in Saturn's magnetosphere utilizing a forward model

NASA Astrophysics Data System (ADS)

Wilson, R. J.; Bagenal, F.; Persoon, A. M.

2017-07-01

The Cassini Plasma Spectrometer instrument gathered thermal ion data at Saturn from 2004 to 2012, predominantly observing water group ions and protons. Plasma parameters, with uncertainties, for those two ion species are derived using a forward model of anisotropic convected Maxwellians moving at a shared velocity. The resulting data set is filtered by various selection criteria to produce a survey of plasma parameters derived within 10° of the equator at radial distances of 5.5 to 30 RS (1 RS = Saturn's radius). The previous 2008 work used a simpler method and had just 150 records over 5 orbits; this comprehensive survey has 9736 records over all 9 years. We present the results of this survey and compare them with a previous survey derived from numerical moments, highlighting the differences between the reported densities and temperatures from the two methods. Radial profiles of the plasma parameters in the inner and middle magnetospheres out to ≈22RS are stable year by year, but variable at distances larger than 23 RS near the magnetopause. New results include proton densities increasing in the near magnetopause region, suggestive of plasma mixing; evidence for the global electric field in Saturn's inner magnetosphere extends out to ≈15RS; no evidence for supercorotating plasma nor the middle magnetosphere "plasma cam" feature is present; the thermal plasma β is found to exceed unity at equatorial distances greater than 15 RS.

On the Azimuthal Variation of Core Plasma in the Equatorial Magnetosphere

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Craven, P. D.; Comfort, R. H.; Moore, T. E.

1995-01-01

Previous results of plasmapause position surveys have been synthesized into a description of the underlying global distribution of plasmasphere-like or core plasma densities unique to a steady state magnetosphere. Under these steady conditions, the boundary between high- and low-density regions is taken to represent the boundary between diurnal near-corotation and large-scale circulation streamlines that traverse the entire magnetosphere. Results indicate a boundary that has a pronounced bulge in the dusk sector that is rotated westward and markedly reduced in size at increased levels of geomagnetic activity (and presumably magnetospheric convection). The derived profile is empirical confirmation of an underlying 'tear drop' distribution of core plasma, which is valid only for prolonged steady conditions and is somewhat different from that associated with the simple superposition of sunward flow and corotation, both in its detailed shape and in its varying orientation. Variation away from the tear drop profile suggests that magnetospheric circulation departs from a uniform flow field, having a radial dependence with respect to the Earth that is qualitatively consistent with electrostatic shielding of the convection electric field and which is rotated westward at increased levels of geophysical activity.

Field and plasma periodicities in Saturn's equatorial middle magnetosphere: Links between the asymmetric ring current and plasma circulation

NASA Astrophysics Data System (ADS)

Kivelson, Margaret; Southwood, David

Superimposed on the predominantly dipolar field of Saturn's middle magnetosphere (here taken as between 5 and 10 RS) are perturbations of a few nT amplitude that vary with the SKR periodicity. Andrews and coworkers (2008) have determined that averages of the perturbations of the radial and azimuthal field components vary roughly sinusoidally and in quadrature, with the radial component leading. Thus these two components of the magnetic perturbations can be represented as an approximately uniform field rotating in the sense of Saturn's rotation (Espinosa et al., 2003). This perturbation field is referred to by Southwood and Kivelson (2007) as the cam field. Andrews et al. (2008) show that perturbation of the theta component, (theta is colatitude) is also nearly sinusoidal and in-phase with the radial perturbations. It follows that near the equator variations of the field magnitude are also in phase with the radial perturbations. Provan et al. (2009) and Khurana et al. (2009) have attributed the periodicity of the field magnitude to an asymmetric ring current. Saturn's asymmetric ring current is not fixed in local time,as it is at Earth, but rotates quasi-rigidly at the SKR period. A distributed, rotating field-aligned current (FAC) system must develop between regions with an excess of or a dearth of azimuthal current but, because those FACs spread over a large spatial region, the associated current density will be smaller than the current density of the more localized cam current system. Thus, it is the electrons associated with the latter currents that are likely to drive the periodically modulated SKR signals. The ring current of the middle magnetosphere is dominated by inertial currents carried by the thermal plasma (Sergis et al., 2010), but the variation of azimuthal current may arise either from density variations or variations of plasma beta. In either case, the current pattern must drive a circulation of the plasma in the middle magnetosphere. [A circulating

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 ellipticalmore » 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.« less

Plasma Distribution in Mercury's Magnetosphere Derived from MESSENGER Magnetometer and Fast Imaging Plasma Spectrometer Observations

NASA Technical Reports Server (NTRS)

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

2014-01-01

We assess the statistical spatial distribution of plasma in Mercury's magnetosphere from observations of magnetic pressure deficits and plasma characteristics by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The statistical distributions of proton flux and pressure were derived from 10months of Fast Imaging Plasma Spectrometer (FIPS) observations obtained during the orbital phase of the MESSENGER mission. The Magnetometer-derived pressure distributions compare favorably with those deduced from the FIPS observations at locations where depressions in the magnetic field associated with the presence of enhanced plasma pressures are discernible in the Magnetometer data. The magnitudes of the magnetic pressure deficit and the plasma pressure agree on average, although the two measures of plasma pressure may deviate for individual events by as much as a factor of approximately 3. The FIPS distributions provide better statistics in regions where the plasma is more tenuous and reveal an enhanced plasma population near the magnetopause flanks resulting from direct entry of magnetosheath plasma into the low-latitude boundary layer of the magnetosphere. The plasma observations also exhibit a pronounced north-south asymmetry on the nightside, with markedly lower fluxes at low altitudes in the northern hemisphere than at higher altitudes in the south on the same field line. This asymmetry is consistent with particle loss to the southern hemisphere surface during bounce motion in Mercury's offset dipole magnetic field.

Plasma circulation in Jupiter's magnetosphere

NASA Astrophysics Data System (ADS)

Chané, E.

2017-12-01

We are using our three-dimensional global MHD model of Jupiter's magnetosphere to study the plasma circulation in the magnetodisk. We show that the Iogenic plasma does not travel outward axisymmetrically but rather forms a long spiral arm of high density corotating with the planet. This leads to periodic phenomena in the magnetodisk: for instance, every rotation period, a region of high density is rapidly moving outward on the pre-noon sector. This leads to shearing motions that generate field aligned currents and periodically affect the main oval in this sector.We will also show how the interplanetary magnetic field influences the position of the magnetodisk in our simulations, displacing the current sheet above and below the equatorial plan. We will discuss how this is affecting the depleted flux-tubes returning from the night-side after unloading most of their plasma in the magnetotail (Vasyliunas cycle) and see how they can then move above or below the magnetodisk when arriving at dawn and then reconnect with the interplanetary magnetic field on the day-side.

Electrostatic and electromagnetic gyroharmonic emissions due to energetic electrons in magnetospheric plasma

NASA Technical Reports Server (NTRS)

Curtis, S. A.; Wu, C. S.

1979-01-01

The paper derives the growth rates and growth lengths of the electrostatic emission for spatially homogeneous and inhomogeneous energetic electrons, and numerically evaluates the growth rate and growth length spectra for several parameter sets representative of magnetospheric plasmas. In addition, the growth rates are derived for the case of electromagnetic emission modeled by the ordinary mode. The numerical results of the electromagnetic and electrostatic cases are compared with observations made by satellites in the earth's magnetosphere. It is concluded that the electrostatic gyroharmonic excitation is possible without the cold composition of plasma which is often postulated in the existing literature.

Can Steady Magnetospheric Convection Events Inject Plasma into the Ring Current?

NASA Astrophysics Data System (ADS)

Lemon, C.; Chen, M. W.; Guild, T. B.

2009-12-01

Steady Magnetospheric Convection (SMC) events are characterized by several-hour periods of enhanced convection that are devoid of substorm signatures. There has long been a debate about whether substorms are necessary to inject plasma into the ring current, or whether enhanced convection is sufficient. If ring current injections occur during SMC intervals, this would suggest that substorms are unnecessary. We use a combination of simulations and data observations to examine this topic. Our simulation model computes the energy-dependent plasma drift in a self-consistent electric and magnetic field, which allows us to accurately model the transport of plasma from the plasma sheet (where the plasma pressure is much larger than the magnetic pressure) into the inner magnetosphere (where plasma pressure is much less than the magnetic pressure). In regions where the two pressures are comparable (i.e. the inner plasma sheet), feedback between the plasma and magnetic field is critical for accurately modeling the physical evolution of the system. Our previous work has suggested that entropy losses in the plasma sheet (such as caused by substorms) may be necessary to inject a ring current. However, it is not yet clear whether other small-scale processes (e.g. bursty bulk flows) can provide sufficient entropy loss in the plasma sheet to allow for the penetration of plasma into the ring current. We combine our simulation results with data observations in order to better understand the physical processes required to inject a ring current.

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.

Physics of the Jovian Magnetosphere

NASA Astrophysics Data System (ADS)

Dessler, A. J.

2002-08-01

List of tables; Foreword James A. Van Allen; Preface; 1. Jupiter's magnetic field and magnetosphere Mario H. Acuña, Kenneth W. Behannon and J. E. P. Connerney; 2. Ionosphere Darrell F. Strobel and Sushil K. Atreya; 3. The low-energy plasma in the Jovian magnetosphere J. W. Belcher; 4. Low-energy particle population S. M. Krimigis and E. C. Roelof; 5. High-energy particles A. W. Schardt and C. K. Goertz; 6. Spectrophotometric studies of the Io torus Robert A. Brown, Carl B. Pilcher and Darrell F. Strobel; 7. Phenomenology of magnetospheric radio emissions T. D. Carr, M. D. Desch and J. K. Alexander; 8. Plasma waves in the Jovian magnetosphere D. A. Gurnett and F. L. Scarf; 9. Theories of radio emissions and plasma waves Melvyn L. Goldstein and C. K. Goertz; 10. Magnetospheric models T. W. Hill, A. J. Dessler and C. K. Goertz; 11. Plasma distribution and flow Vytenis M. Vasyliunas; 12. Microscopic plasma processes in the Jovian magnetosphere Richard Mansergh Thorne; Appendixes; References; Index.

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

Neutral and Plasma Sources in the Saturn's Magnetosphere

NASA Astrophysics Data System (ADS)

Jurac, S.; Johnson, R. E.

1999-05-01

The heavy ion plasma in Saturnian inner magnetosphere is derived from the icy satellites and ring particles imbedded in the plasma. Recent Hubble Space Telescope measurements of the densities of neutral OH molecules which co-exist with and are precursors of the plasma ions have constrained models for the plasma sources. Richardson et al (1998) considered all existing HST observations and derived water-like neutral densities and estimated required sources to maintain equilibrium. Their neutral densities show maximum close to Enceladus (where the E-ring density peaks) and their total neutral source rate needed to maintain neutrals in steady state is for an order of magnitude larger than source rate given by Shi et al (1995). We model the sputtering of water-ice using the recently developed Monte-Carlo collisional transport code, and calculate neutral supply rates from sputtering of Enceladus and the E-ring. This collisional code, used previously to evaluate sputtering from the interstellar grains (Jurac et al, 1998) is modified to include electronic processes relevant to water-ice sputtering, and then applied to the E-ring grains. It is shown that the grain erosion rate increases substantially when the ion penetration depth becomes comparable to the grain radius. The sputtering and collection rates for plasma ions and neutrals are evaluated and it is shown that the E-ring might be the dominant source of water-like neutrals in the Saturnian magnetosphere. We also describe competition between grain growth and erosion and discuss implications to the existing E-ring evolutionary models. References: Jurac S., R. E. Johnson, B. Donn; Astroph. J. 503, 247, 1998 Richardson, J. D., A. Eviatar, M. A. McGrath, V. M. Vasyliunas; J. Geophys. Res., 103, 20245, 1998 Shi, M., R.A. Baragiola, D.E. Grosjean, R.E. Johnson, S. Jurac and J. Schou; J. Geophys. Res., 100, 26387, 1995.

Plasma convection in Saturn's magnetosphere: A diagnosis using Cassini observations of the magnetic field spiral

NASA Astrophysics Data System (ADS)

Smith, Edward; Dougherty, Michele K.

The global distribution of plasma and its flows inside Saturn's magnetosphere is complex. The large satellites in the inner magnetosphere are a persistent source of plasma that must make its way into the outer magnetosphere and exit through the magnetotail. The mass loaded into the magnetic field stretches the field lines outward resulting in the formation of the equatorial current sheet. The outward radial flow causes the closed stretched fields to spiral out of magnetic meridian planes. The angle associated with the spiralling is given by the ratio of the azimuthal field component, B , to the radial component Br : tan = B / Br . The magnetic spiral is directly related to the corresponding components of plasma velocity, v and v r, provided the conductivity of the ionosphere, , is high enough to enforce co-rotation of the field lines. If, as has been inferred, the conductivity is low, the field and plasma do not co-rotate and the conductivity also enters the expression for . Conditions are more uncertain further out in the magnetosphere where convective motions associated with magnetic reconnection between planetary and interplanetary fields and the motion of the shocked solar wind become dominant. The prevailing model is a superposition of two modes of plasma circulation inside the magnetosphere and magnetotail, the Dungey and Vasyliunas cycles, that depend on radial distance and local time with an x-line in the midnight sector that separates the two cycles. The measured spiral angle will be affected by this complexity and holds the promise of distinguishing the relative influences of v ,v r and . The two field components that define the spiral angle are also involved in the transfer of angular momentum from the ionosphere to the magnetospheric plasma and the outward mass flux. The spiral should also contain evidence, especially at high latitudes, of the return of the current to the ionosphere from the current sheet. Our major objective, therefore, is to

Plasma in Saturn's Nightside Magnetosphere and the Implications for Global Circulation

NASA Technical Reports Server (NTRS)

McAndrews, H.J.; Thomsen, M.F.; Arridge, C.S.; Jackman, C.M.; Wilson, R.J.; Henderson, M.G.; Tokar, R.L.; Khurana, K.K.; Sittler, E. C.; Coates, A.J.;

PC-5 Waves and Low Energy Plasma in the Outer Magnetosphere

NASA Technical Reports Server (NTRS)

Gallanger, Dennis L.; Vaisberg, Oleg L.; Coffey, Victoria N.

1999-01-01

The Interball Tail Probe crosses the dayside magnetopause at low latitudes where it frequently measures low energy ion plasma (<100 eV) in the outer magnetosphere. We present the wave characteristics associated with this cold component.

Ganymede's magnetosphere: Magnetometer overview

NASA Astrophysics Data System (ADS)

Kivelson, M. G.; Warnecke, J.; Bennett, L.; Joy, S.; Khurana, K. K.; Linker, J. A.; Russell, C. T.; Walker, R. J.; Polanskey, C.

1998-09-01

Ganymede presents a unique example of an internally magnetized moon whose intrinsic magnetic field excludes the plasma present at its orbit, thereby forming a magnetospheric cavity. We describe some of the properties of this mini-magnetosphere, embedded in a sub-Alfvénic flow and formed within a planetary magnetosphere. A vacuum superposition model (obtained by adding the internal field of Ganymede to the field imposed by Jupiter) organizes the data acquired by the Galileo magnetometer on four close passes in a useful, intuitive fashion. The last field line that links to Ganymede at both ends extends to ~2 Ganymede radii, and the transverse scale of the magnetosphere is ~5.5 Ganymede radii. Departures from this simple model arise from currents flowing in the Alfvén wings and elsewhere on the magnetopause. The four passes give different cuts through the magnetosphere from which we develop a geometric model for the magnetopause surface as a function of the System III location of Ganymede. On one of the passes, Ganymede was located near the center of Jupiter's plasma disk. For this pass we identify probable Kelvin-Helmholtz surface waves on the magnetopause. After entering the relatively low-latitude upstream magnetosphere, Galileo apparently penetrated the region of closed field lines (ones that link to Ganymede at both ends), where we identify predominantly transverse fluctuations at frequencies reasonable for field line resonances. We argue that magnetic field measurements, when combined with flow measurements, show that reconnection is extremely efficient. Downstream reconnection, consequently, may account for heated plasma observed in a distant crossing of Ganymede's wake. We note some of the ways in which Ganymede's unusual magnetosphere corresponds to familiar planetary magnetospheres (viz., the magnetospheric topology and an electron ring current). We also comment on some of the ways in which it differs from familiar planetary magnetospheres (viz., relative

Fifty-one years of Los Alamos Spacecraft

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenimore, Edward E.

2014-09-04

From 1963 to 2014, the Los Alamos National Laboratory was involved in at least 233 spacecraft. There are probably only one or two institutions in the world that have been involved in so many spacecraft. Los Alamos space exploration started with the Vela satellites for nuclear test detection, but soon expanded to ionospheric research (mostly barium releases), radioisotope thermoelectric generators, solar physics, solar wind, magnetospheres, astrophysics, national security, planetary physics, earth resources, radio propagation in the ionosphere, and cubesats. Here, we present a list of the spacecraft, their purpose, and their launch dates for use during RocketFest

Magnetospheric and auroral plasmas: A short survey of progress, 1971 - 1975

NASA Technical Reports Server (NTRS)

Frank, L. A.

1975-01-01

Milestones in researches of auroral and magnetospheric plasmas for the past quadrennium 1971 - 1975 are reviewed. Findings, including those of the polar cusp, the polar wind, the explosive disruptions of the magnetotail, the interactions of hot plasmas with the plasmapause, the auroral field-aligned currents, and the striking 'inverted-V' electron precipitation events, are reported. Solutions to major questions concerning the origins and acceleration of these plasmas are discussed. A comprehensive bibliography of current research is included.

Magnetospheric Multiscale Mission Observations of Magnetic Flux Ropes in the Earth's Plasma Sheet

NASA Astrophysics Data System (ADS)

Slavin, J. A.; Akhavan-Tafti, M.; Poh, G.; Le, G.; Russell, C. T.; Nakamura, R.; Baumjohann, W.; Torbert, R. B.; Gershman, D. J.; Pollock, C. J.; Giles, B. L.; Moore, T. E.; Burch, J. L.

2017-12-01

A major discovery by the Cluster mission and the previous generation of science missions is the presence of earthward and tailward moving magnetic flux ropes in the Earth's plasma sheet. However, the lack of high-time resolution plasma measurements severely limited progress concerning the formation and evolution of these reconnection generated structures. We use high-time resolution magnetic and electric field and plasma measurements from the Magnetospheric Multiscale mission's first tail season to investigate: 1) the distribution of flux rope diameters relative to the local ion and electron inertial lengths; 2) the internal force balance sustaining these structures; and 3) the magnetic connectivity of the flux ropes to the Earth and/or the interplanetary medium; 4) the specific entropy of earthward moving flux ropes and the possible effect of "buoyancy" on how deep they penetrate into the inner magnetosphere; and 5) evidence for coalescence of adjacent flux ropes and/or the division of existing flux ropes through the formation of secondary X-lines. The results of these initial analyses will be discussed in terms of their implications for reconnection-driven magnetospheric dynamics and substorms.

Plasma bulk flow in Jupiter's dayside middle magnetosphere

NASA Technical Reports Server (NTRS)

Sands, Mark R.; Mcnutt, Ralph L., Jr.

1988-01-01

Using the plasma data obtained during the Voyager 1 encounter and the full response function of the Plasma Science (PLS) experiment, convective plasma velocities have been determined in the dayside middle magnetosphere of Jupiter (r = 10-25 Jupiter radii). It is found that temperature anisotropies have very little effect on plasma velocity determination and that the plasma data are well approximated by convected, isotropic Maxwellian ion distribution functions. The insensitivity of the analysis to any thermal anisotropies which may exist allows a good determination of the bulk plasma flow velocity. In addition to the subcorotational azimuthal flow, there exists a substantial nonazimuthal component of plasma flow. This nonazimuthal flow is mostly aligned (antialigned) with the local magnetic field but also exhibits a cross-field component. The velocity pattern is inconsistent with enhanced plasma outflow in the active sector, as suggested by the corotating convection model of plasma transport. The contribution of field-aligned flow along the curved magnetic field lines to the stress on the magnetic field is evaluated. In the region studied, such flow contributes up to one half the stress produced by the azimuthal plasma flow.

Giant planet magnetospheres

NASA Technical Reports Server (NTRS)

Bagenal, Fran

1992-01-01

The classification of the giant planet magnetospheres into two varieties is examined: the large symmetric magnetospheres of Jupiter and Saturn and the smaller irregular ones of Uranus and Neptune. The characteristics of the plasma and the current understanding of the magnetospheric processes are considered for each planet. The energetic particle populations, radio emissions, and remote sensing of magnetospheric processes in the giant planet magneotospheres are discussed.

The Transport of Plasma and Magnetic Flux in Giant Planet Magnetospheres

NASA Astrophysics Data System (ADS)

Russell, C. T.

2013-05-01

Both Jupiter and Saturn have moons that add significant quantities of neutrals and/or dust beyond geosynchronous orbit. This material becomes charged and interacts with the planetary plasma that is "orbiting" the planets at near corotational speeds, driven by the planetary ionospheres. Since this speed is greater than the keplerian orbital speed at these distances, the net force on the newly added charged mass is outward. The charged material is held in place by the magnetic field which stretches to the amount needed to balance centripetal and centrifugal forces. The currents involved in this process close in the ionosphere which is an imperfect conductor and the feet of the field lines hence slip poleward and the material near the equator moves outward. This motion allows the magnetosphere to divest itself of the added mass by transferring it to the magnetotail. The magnetotail in turn can rid itself of the newly added mass by the process of reconnection, interior to the region of added mass, freeing an island of magnetized plasma which then moves down the magnetotail no longer connected to the magnetosphere. This maintains a quasi-stationary conservation of mass in the magnetosphere with roughly constant mass and "periodic" disturbances. However, there is one other steady state the magnetosphere needs to maintain. It needs to replace the mass loaded flux tubes with emptied flux tubes. Thus the "emptied" flux tubes in the tail must move inward against the outgoing mass-loaded flux tubes. That they are buoyant is a help in this regard but it appears also to be helpful if the returning flux separates into thin flux tubes, just like air bubbles rising in a container with a leak in the bottom. In this way the magnetospheres of Jupiter and Saturn maintain their dynamic, steady-state convection patterns.

Evidence of m = 1 density mode (plasma cam) in Saturn's rotating magnetosphere

NASA Astrophysics Data System (ADS)

Goldstein, J.; Waite, J. H.; Burch, J. L.; Livi, R.

2016-03-01

Cassini field and plasma data measured in the rotating Saturn Longitude System 3 (SLS3) coordinate system show positive evidence of structure whose dominant azimuthal wave number is m = 1: a long-lived, nonaxisymmetric, cam-shaped, global plasma distribution in Saturn's magnetosphere. Previous studies have identified evidence of this plasma cam in wave-derived electron density data and in Cassini Plasma Spectrometer (CAPS) W+ ion counts data. In this paper we report the first comprehensive analysis of CAPS ion moments data to identify the m = 1 density cam. We employ a multiyear, multispecies database of 685,678 CAPS density values, binned into a 1 RS by 4.8° discretized grid, spanning 4-19 RS. Fourier (harmonic) analysis shows that at most radial distances the dominant azimuthal mode is m = 1, for both W+ and H+ ion distributions. The majority (63%) of m = 1 ion peaks are clustered in an SLS3 quadrant centered at 330°. The plasma cam's existence has important implications for the global interchange-driven convection cycle and is a clue to solving the mystery of the rotational periodicities in Saturn's magnetosphere.

Circulation of Plasma in the Jovian Magnetosphere as Inferred from the Galileo Magnetometer Observations

NASA Astrophysics Data System (ADS)

Yu, Z. J.; Russell, C. T.; Kivelson, M. G.; Khurana, K. K.

2000-10-01

Massloading of the jovian magnetosphere by the addition of ions at the moon Io is the ultimate engine of the circulation of the magnetospheric plasma. In steady state the radial density profile enables the radial outflow velocity to be calculated from the mass addition rate. Some of these ions are lost from the field lines through pitch angle diffusion. Expected loss rates can be calculated from the fluctuation level in the magnetic field. Radial velocities can be calculated from observations of the Europa wake and force balance in the magnetodisk. The resulting transport times are shorter than the pitch angle scattering loss times so that most of the plasma is transported to the tail and lost by magnetic island formation. In turn the island formation process (reconnection) depletes magnetic field lines making them buoyant and allowing them to "float" back to the inner magnetosphere. In the torus these depleted flux tubes can be seen as thin tubes with stronger than the ambient field strength, implying plasma pressures about 2% of the magnetic field and ion temperatures principally in the range 30-150 eV. When the depleted flux tubes reach the orbit of Io where the energy density of the plasma drops these depleted flux tubes become indistinguishable from the ambient plasma, completing the circulation loop.

Mercury's Solar Wind Interaction as Characterized by Magnetospheric Plasma Mantle Observations With MESSENGER

NASA Astrophysics Data System (ADS)

Jasinski, Jamie M.; Slavin, James A.; Raines, Jim M.; DiBraccio, Gina A.

2017-12-01

We analyze 94 traversals of Mercury's southern magnetospheric plasma mantle using data from the MESSENGER spacecraft. The mean and median proton number densities in the mantle are 1.5 and 1.3 cm-3, respectively. For sodium number density these values are 0.004 and 0.002 cm-3. Moderately higher densities are observed on the magnetospheric dusk side. The mantle supplies up to 1.5 × 108 cm-2 s-1 and 0.8 × 108 cm-2 s-1 of proton and sodium flux to the plasma sheet, respectively. We estimate the cross-electric magnetospheric potential from each observation and find a mean of 19 kV (standard deviation of 16 kV) and a median of 13 kV. This is an important result as it is lower than previous estimations and shows that Mercury's magnetosphere is at times not as highly driven by the solar wind as previously thought. Our values are comparable to the estimations for the ice giant planets, Uranus and Neptune, but lower than Earth. The estimated potentials do have a very large range of values (1-74 kV), showing that Mercury's magnetosphere is highly dynamic. A correlation of the potential is found to the interplanetary magnetic field (IMF) magnitude, supporting evidence that dayside magnetic reconnection can occur at all shear angles at Mercury. But we also see that Mercury has an Earth-like magnetospheric response, favoring -BZ IMF orientation. We find evidence that -BX orientations in the IMF favor the southern cusp and southern mantle. This is in agreement with telescopic observations of exospheric emission, but in disagreement with modeling.

Mercury's solar wind interaction as characterized by magnetospheric plasma mantle observations with MESSENGER

NASA Astrophysics Data System (ADS)

Jasinski, J. M.; Slavin, J. A.; Raines, J. M.; DiBraccio, G. A.

2017-12-01

We analyze 94 traversals of Mercury's magnetospheric plasma mantle using data from the MESSENGER spacecraft. The mean and median proton number density in the mantle are 1.5 and 1.3 cm-3, respectively. For sodium number density these values are 0.004 and 0.002 cm-3. Moderately higher densities are observed on the magnetospheric dusk side. The mantle supplies up to 1.5 x 108 cm-2 s-1 and 0.8 x 108cm-2 s-1 of proton and sodium flux to the plasma sheet, respectively. We estimate the cross-electric magnetospheric potential from each observation and find a mean of 19 kV (standard deviation of 16 kV) and a median of 13 kV. This is an important result as it is lower than previous estimations and shows that Mercury's magnetosphere is at times not as highly driven by the solar wind as previously thought. Our values are comparable to the estimations for the ice giant planets, Uranus and Neptune, but lower than Earth. The estimated potentials do have a very large range of values (1 - 74 kV), showing that Mercury's magnetosphere is highly dynamic. A correlation of the potential is found to the interplanetary magnetic field (IMF) magnitude, supporting evidence that dayside magnetic reconnection can occur at all shear angles at Mercury. But we also see that Mercury has an Earth-like magnetospheric response, favoring -BZ IMF orientation. We find evidence that -BX orientations in the IMF favor the southern cusp and southern mantle. This is in agreement with telescopic observations of exospheric emission, but in disagreement with modeling.

Conductance Effects on Inner Magnetospheric Plasma Morphology: Model Comparisons with IMAGE EUV, MENA, and HENA Data

NASA Technical Reports Server (NTRS)

Liemohn, M.; Ridley, A. J.; Kozyra, J. U.; Gallagher, D. L.; Brandt, P. C.; Henderson, M. G.; Denton, M. H.; Jahn, J. M.; Roelof, E. C.; DeMajistre, R. M.

2004-01-01

Modeling results of the inner magnetosphere showing the influence of the ionospheric conductance on the inner magnetospheric electric fields during the April 17, 2002 magnetic storm are presented. Kinetic plasma transport code results are analyzed in combination with observations of the inner magnetospheric plasma populations, in particular those from the IMAGE satellite. Qualitative and quantitative comparisons are made with the observations from EW, MENA, and HENA, covering the entire energy range simulated by the model (0 to 300 keV). The electric field description, and in particular the ionospheric conductance, is the only variable between the simulations. Results from the data-model comparisons are discussed, detailing the strengths and weaknesses of each conductance choice for each energy channel.

HOPE Survey of the Near-Equatorial Magnetosphere Plasma Environment

NASA Astrophysics Data System (ADS)

Fernandes, P. A.; Larsen, B.; Skoug, R. M.; Reeves, G. D.; Denton, M.; Thomsen, M. F.; Funsten, H. O.; Jahn, J. M.; MacDonald, E.

2016-12-01

The twin Van Allen Probes spacecraft have completed over four years on-orbit resulting in more than 2 full precessions in local time. We present for the first time a summary of the plasma environment at the near-equatorial magnetosphere inside geostationary orbit from the HOPE (Helium-Oxygen-Proton-Electron) spectrometer. This rich data set is comprised of 48 months of release 3 particle data for electrons, protons, helium ions, and oxygen ions for energies from 15 eV to 50 keV. For each species we calculate median fluxes and flux distributions over the instrument energy range. We present the L and MLT (magnetic local time) distributions of these fluxes, percentiles, and flux ratios. This full-coverage survey, over an extended duration and range of energies and L-shells, examines the ion and electron fluxes and their ratios as a function of solar and geomagnetic activity. This detailed observation of the near-equatorial plasma environment reproduces well-known phenomenology in the energy ranges of overlap, and interpretation focuses on the structure, composition, and dynamics of the inner magnetosphere for various degrees of geomagnetic activity.

Plasma precipitation on Mercury's nightside and its implications for magnetospheric convection and exosphere generation.

NASA Astrophysics Data System (ADS)

Raines, J. M.; Slavin, J. A.; Tracy, P.; Gershman, D. J.; Zurbuchen, T.; Korth, H.; Anderson, B. J.; Solomon, S. C.

2015-12-01

Plasma impact onto Mercury's surface can be an important contributor to Mercury's exosphere through the process of ion sputtering. Under some circumstances, this process can produce a substantial fraction of the exosphere. When the impacting plasma originates from the magnetosphere itself, this sputtering process can conversely be considered as a sink for the plasma of the Mercury magnetosphere, providing evidence for the processes at work in that system. One such process is reconnection in Mercury's magnetotail, which can accelerate ions and electrons from the central plasma sheet toward the nightside of the planet. By analogy with processes at Earth, it is hypothesized that as these flows approach the planet, much of the plasma is diverted from impact onto the surface by the increasingly strong planetary magnetic field closer to the planet. The remainder of the plasma is expected to follow nearly dipolar field lines, impacting the nightside surface and potentially contributing to field-aligned currents. We present the first direct evidence that this process is operating at Mercury. We examine ion precipitation events on Mercury's nightside with the Fast Imaging Plasma Spectrometer (FIPS) on the MESSENGER spacecraft, which orbited Mercury from 2011 to 2015. We characterize the energy distributions of these events and their extent in latitude and local time. We use these observations to predict the precipitating proton flux from altitudes as low as 11 km. We use this information to bound the region of Mercury's surface that remains protected from plasma bombardment by the planetary dipole magnetic field, and to explore the implications of this information for magnetospheric convection and exosphere generation at Mercury.

Plasma precipitation on Mercury's nightside and its implications for magnetospheric convection and exosphere generation.

NASA Astrophysics Data System (ADS)

Raines, J. M.; Slavin, J. A.; Tracy, P.; Gershman, D. J.; Zurbuchen, T.; Dewey, R. M.; Sarantos, M.

2016-12-01

Plasma impact onto Mercury's surface can be an important contributor to Mercury's exosphere through the process of ion sputtering. Under some circumstances, this process can produce a substantial fraction of the exosphere. When the impacting plasma originates from the magnetosphere itself, this sputtering process can conversely be considered as a sink for the plasma of the Mercury magnetosphere, providing evidence for the processes at work in that system. One such process is reconnection in Mercury's magnetotail, which can accelerate ions and electrons from the central plasma sheet toward the nightside of the planet. By analogy with processes at Earth, it is hypothesized that as these flows approach the planet, much of the plasma is diverted from impact onto the surface by the increasingly strong planetary magnetic field closer to the planet. The remainder of the plasma is expected to follow nearly dipolar field lines, impacting the nightside surface and potentially contributing to field-aligned currents. We present the first direct evidence that this process is operating at Mercury. We examine ion precipitation events on Mercury's nightside with the Fast Imaging Plasma Spectrometer (FIPS) on the MESSENGER spacecraft, which orbited Mercury from 2011 to 2015. We characterize the energy distributions of these events and their extent in latitude and local time. We use these observations to predict the precipitating proton flux from altitudes as low as 11 km. We use this information to bound the region of Mercury's surface that remains protected from plasma bombardment by the planetary dipole magnetic field, and to explore the implications of this information for magnetospheric convection and exosphere generation at Mercury.

Fine structure of striations observed in barium plasma injections in the magnetospheric cleft

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simons, D.J.; Eastman, T.E.; Pongratz, M.B.

1976-01-01

In January and November of 1975, the Los Alamos Scientific Laboratory sponsored four high altitude shaped charge barium plasma injections in the magnetospheric cleft region. These experiments were TORDO UNO (January 6), TORDO DOS (January 11), PERIQUITO UNO (November 25), and PERIQUITO DOS (November 28). All four injections took place near 500 km altitude, and optical data were taken from two aircraft and a ground station. The TORDO DOS and the PERIQUITO experiments showed rapid formation of striations (within one minute after injection), and fast horizontal spreading in contrast with TORDO UNO. In PERIQUITO DOS, the debris cloud spread magneticallymore » east-west with a small net northerly motion. TORDO UNO shows very rapid poleward motion, and the remaining two events resulted in magnetically east-west horizontal spreading, with no noticeable poleward motion. Striations observed in the PERIQUITO DOS experiment separate in opposite directions with relative velocities of up to 3 km/sec. These field-aligned structures appear to form in sheets of approximately constant magnetic latitude. Significant spatial variations occur on a scale of less than 200 meters. Spatial frequency power spectra across these striations have been determined at various times. Observations of the debris cloud and the fast barium streak show strong field-aligned coherency of striation fine structure, indicating a field line mapping of transverse electric fields and gradients.« less

Plasma composition in Jupiter's magnetosphere - Initial results from the Solar Wind Ion Composition Spectrometer

NASA Technical Reports Server (NTRS)

Geiss, J.; Gloeckler, G.; Balsiger, H.; Fisk, L. A.; Galvin, A. B.; Gliem, F.; Hamilton, D. C.; Ipavich, F. M.; Livi, S.; Mall, U.

1992-01-01

The ion composition in the Jovian environment was investigated with the Solar Wind Ion Composition Spectrometer on board Ulysses. A hot tenuous plasma was observed throughout the outer and middle magnetosphere. In some regions two thermally different components were identified. Oxygen and sulfur ions with several different charge states, from the volcanic satellite Io, make the largest contribution to the mass density of the hot plasma, even at high latitude. Solar wind particles were observed in all regions investigated. Ions from Jupiter's ionosphere were abundant in the middle magnetosphere, particularly in the high-latitude region on the dusk side, which was traversed for the first time.

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.

Simulating the interplay between plasma transport, electric field, and magnetic field in the near-earth nightside magnetosphere

NASA Astrophysics Data System (ADS)

Gkioulidou, Malamati

The convection electric field resulting from the coupling of the Earth's magnetosphere with the solar wind and interplanetary magnetic field (IMF) drives plasma in the tail plasma sheet earthward. This transport and the resulting energy storage in the near Earth plasma sheet are important for setting up the conditions that lead to major space weather disturbances, such as storms and substorms. Penetration of plasma sheet particles into the near-Earth magnetosphere in response to enhanced convection is crucial to the development of the Region 2 field-aligned current system and large-scale magnetosphere-ionosphere (M-I) coupling, which results in the shielding of the convection electric field. In addition to the electric field, plasma transport is also strongly affected by the magnetic field, which is distinctly different from dipole field in the inner plasma sheet and changes with plasma pressure in maintaining force balance. The goal of this dissertation is to investigate how the plasma transport into the inner magnetosphere is affected by the interplay between plasma, electric field and magnetic field. For this purpose, we conduct simulations using the Rice Convection Model (RCM), which self-consistently calculates the electric field resulting from M-I coupling. In order to quantitatively evaluate the interplay, we improved the RCM simulations by establishing realistic plasma sheet particle sources, by incorporating it with a modified Dungey force balance magnetic field solver (RCM-Dungey runs), and by adopting more realistic electron loss rates. We found that plasma sheet particle sources strongly affect the shielding of the convection electric field, with a hotter and more tenuous plasma sheet resulting in less shielding than a colder and denser one and thus in more earthward penetration of the plasma sheet. The Harang reversal, which is closely associated with the shielding of the convection electric field and the earthward penetration of low-energy protons, is

Particle transport characteristics of the RT-1 magnetospheric plasma using gas-puffing modulation technique

NASA Astrophysics Data System (ADS)

Kenmochi, Naoki; Nishiura, Masaki; Yoshida, Zensho; Sugata, Tetsuya; Nakamura, Kaori; Katsura, Shotaro

2017-10-01

The Ring Trap 1 (RT-1) device creates a laboratory magnetosphere that is realized by a levitated superconducting ring magnet in vacuum. The RT-1 experiment has demonstrated the self-organization of a plasma clump with a steep density gradient; a peaked density distribution is spontaneously created through `inward diffusion'. In order to evaluate particle transport characteristics in the RT-1 magnetospheric plasmas which cause these inward diffusion, density modulation experiments were performed in the RT-1. Density modulation is a powerful method for estimating a diffusion coefficient D and a convection velocity V by puffing a periodic neutral gas. The gas puff modulation causes the change in the electron density measured by two chords of microwave interferometer (the radial positions r = 60 and 70 cm, vertical chord). In the case of 2 Hz gas puff modulation, the phase delay and the modulation-amplitude decay at the chord r = 60 cm are obtained with 15 degree and 0.8, respectively, with respect to the phase and the amplitude at r = 70 cm. The particle balance equations are solved on the assumption of profile shapes for D to evaluate D, V and particle source rate. The result suggests the inward convection in high beta magnetospheric plasmas.

The spatial structure of magnetospheric plasma disturbance estimated by using magnetic data obtained by SWARM satellites.

NASA Astrophysics Data System (ADS)

Yokoyama, Y.; Iyemori, T.; Aoyama, T.

2017-12-01

Field-aligned currents with various spatial scales flow into and out from high-latitude ionosphere. The magnetic fluctuations observed by LEO satellites along their orbits having period longer than a few seconds can be regarded as the manifestations of spatial structure of field aligned currents.This has been confirmed by using the initial orbital characteristics of 3 SWARM-satellites. From spectral analysis, we evaluated the spectral indices of these magnetic fluctuations and investigated their dependence on regions, such as magnetic latitude and MLT and so on. We found that the spectral indices take quite different values between the regions lower than the equatorward boundary of the auroral oval (around 63 degrees' in magnetic latitude) and the regions higher than that. On the other hands, we could not find the clear MLT dependence. In general, the FACs are believed to be generated in the magnetiospheric plasma sheet and boundary layer, and they flow along the field lines conserving their currents.The theory of FAC generation [e.g., Hasegawa and Sato ,1978] indicates that the FACs are strongly connected with magnetospheric plasma disturbances. Although the spectral indices above are these of spatial structures of the FACs over the ionosphere, by using the theoretical equation of FAC generation, we evaluate the spectral indices of magnetospheric plasma disturbance in FAC's generation regions. Furthermore, by projecting the area of fluctuations on the equatorial plane of magnetosphere (i.e. plasma sheet), we can estimate the spatial structure of magnetospheric plasma disturbance. In this presentation, we focus on the characteristics of disturbance in midnight region and discuss the relations to the substorm.

Whistlers in space plasma, their role for particle populations in the inner magnetosphere

NASA Astrophysics Data System (ADS)

Shklyar, David

Of many wave modes, which propagate in the plasmaspheric region of the magnetosphere, whistler waves play the most important role in the dynamics of energetic particles (chiefly elec-trons, but not excepting protons), as their resonant interactions are very efficient. There are three main sources of whistler mode waves in the magnetosphere, namely, lightning strokes, VLF transmitter signals, and far and away various kinds of kinetic instabilities leading to generation of whistler mode waves. Resonant interactions of energetic electrons with whistlers may lead to electron acceleration, scattering into loss-cone, and consequent precipitation into the iono-sphere and atmosphere. While electron resonant interaction with lightning-induced whistlers and VLF transmitter signals may, to a certain approximation, be considered as particle dy-namics in given electromagnetic fields, resonant wave-particle interaction in the case of plasma instability is intrinsically a self-consistent process. An important aspect of whistler-electron interactions (particularly in the case of plasma instability) is the possibility of energy exchange between different energetic electron populations. Thus, in many cases, whistler wave growth rate is determined by "competition" between the first cyclotron and Cerenkov resonances, one (depending on energetic electron distribution) leading to wave growth and the other one to wave damping. Since particles which give rise to wave growth loose their energy, while parti-cles which lead to wave damping gain energy at the expense of the wave, and since the first cyclotron and Cerenkov resonances correspond to different particle energies, wave generation as the result of plasma instability may lead, at the same time, to energy exchange between two populations of energetic particles. While the role of whistlers in dynamics of energetic electrons in the magnetosphere is gener-ally recognized, their role for protons seems to be underestimated. At the same

A Model for Plasma Transport in a Corotation-Dominated Magnetosphere.

NASA Astrophysics Data System (ADS)

Pontius, Duane Henry, Jr.

1988-06-01

The gross structures of the magnetospheres of the outer planets are decided by processes quite different from those predominant in that of the earth. The terrestrial plasmapause, the boundary beyond which plasma motion is principally determined by magnetospheric interaction with the solar wind, is typically inside geosynchronous orbit. Within the plasmasphere, rotational effects are present, but gravity exceeds the centrifugal force of corotation. In contrast, the Jovian plasmasphere extends to a distance at least twenty times farther than synchronous orbit, affording a large region where rotational effects are expected to he clearly manifest (Brice and Ioannidis, 1970). The goal of this thesis is to develop an appropriate theoretical model for treating the problem of plasma transport in a corotation dominated plasmasphere. The model presented here is intended to describe the radial transport of relatively cold plasma having an azimuthally uniform distribution in a dipolar magnetic field. The approach is conceptually similar to that of the radial diffusion model in that small scale motions are examined to infer global consequences, but the physical understanding of those small scale motions is quite different. In particular, discrete flux tubes of small cross section are assumed to move over distances large compared to their widths. The present model also differs from the corotating convection model by introducing a mechanism whereby the conservation of flux tube content along flowlines is violated. However, it is quite possible that a global convection pattern co -exists with the motions described here, leading to longitudinal asymmetries in the plasma distribution.

Identifying Cassini's Magnetospheric Location Using Magnetospheric Imaging Instrument (MIMI) Data and Machine Learning

NASA Astrophysics Data System (ADS)

Vandegriff, J. D.; Smith, G. L.; Edenbaum, H.; Peachey, J. M.; Mitchell, D. G.

2017-12-01

We analyzed data from Cassini's Magnetospheric Imaging Instrument (MIMI) and Magnetometer (MAG) and attempted to identify the region of Saturn's magnetosphere that Cassini was in at a given time using machine learning. MIMI data are from the Charge-Energy-Mass Spectrometer (CHEMS) instrument and the Low-Energy Magnetospheric Measurement System (LEMMS). We trained on data where the region is known based on a previous analysis of Cassini Plasma Spectrometer (CAPS) plasma data. Three magnetospheric regions are considered: Magnetosphere, Magnetosheath, and Solar Wind. MIMI particle intensities, magnetic field values, and spacecraft position are used as input attributes, and the output is the CAPS-based region, which is available from 2004 to 2012. We then use the trained classifier to identify Cassini's magnetospheric regions for times after 2012, when CAPS data is no longer available. Training accuracy is evaluated by testing the classifier performance on a time range of known regions that the classifier has never seen. Preliminary results indicate a 68% accuracy on such test data. Other techniques are being tested that may increase this performance. We present the data and algorithms used, and will describe the latest results, including the magnetospheric regions post-2012 identified by the algorithm.

A DE-1/whistler study of the thermal plasma structure and dynamics in the dusk bulge sector of the magnetosphere

NASA Technical Reports Server (NTRS)

Carpenter, D. L.

1992-01-01

The objective of this research was to obtain new understanding of the thermal plasma structure and dynamics of the plasmasphere bulge region of the magnetosphere, with special emphasis on the erosion process that results in a reduction in plasmasphere size and on the manner in which erosion leads to the presence of patches of dense plasma in the middle and outer afternoon-dusk magnetosphere. Case studies involving data from the DE 1, GEOS 2, and ISEE 1 satellites and from ground whistler stations Siple, Halley, and Kerguelen were used. A copy of the published paper entitled 'A case study of plasma structure in the dusk sector associated with enhanced magnetospheric convection,' is included.

Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

NASA Technical Reports Server (NTRS)

Sittler, E.; Cooper, J.; Simpson, D.; Paterson, W.

2012-01-01

We present the present status of an investigation of the rotation rate of Saturn 's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. (2005) [1] for SOI and similar to that used by Thomsen et al. (2010). This technique allows one to nearly cover the full energy range of the CAPS IMS from 1 V less than or equal to E/Q less than 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll manoeuvres. We have made comparisons with Wilson et al. (2008) [2] (2005-358 and 2005-284) who performs a bi-Maxwellian fit to the ion singles data and our results are nearly identical. We will also make comparisons with results by Thomsen et al. (2010) [3]. Our analysis uses ion composition data to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. Since our analysis is a velocity moments technique it will work within the inner magnetosphere where pickup ions are important and velocity distributions are non-Maxwellian. So, we will present results inside Enceladus' L shell and determine if mass loading is important. In the future we plan to make comparisons with magnetic field observations, use Saturn ionosphere conductivities as

Inner Magnetospheric Superthermal Electron Transport: Photoelectron and Plasma Sheet Electron Sources

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Liemohn, M. W.; Kozyra, J. U.; Moore, T. E.

1998-01-01

Two time-dependent kinetic models of superthermal electron transport are combined to conduct global calculations of the nonthermal electron distribution function throughout the inner magnetosphere. It is shown that the energy range of validity for this combined model extends down to the superthermal-thermal intersection at a few eV, allowing for the calculation of the en- tire distribution function and thus an accurate heating rate to the thermal plasma. Because of the linearity of the formulas, the source terms are separated to calculate the distributions from the various populations, namely photoelectrons (PEs) and plasma sheet electrons (PSEs). These distributions are discussed in detail, examining the processes responsible for their formation in the various regions of the inner magnetosphere. It is shown that convection, corotation, and Coulomb collisions are the dominant processes in the formation of the PE distribution function and that PSEs are dominated by the interplay between the drift terms. Of note is that the PEs propagate around the nightside in a narrow channel at the edge of the plasmasphere as Coulomb collisions reduce the fluxes inside of this and convection compresses the flux tubes inward. These distributions are then recombined to show the development of the total superthermal electron distribution function in the inner magnetosphere and their influence on the thermal plasma. PEs usually dominate the dayside heating, with integral energy fluxes to the ionosphere reaching 10(exp 10) eV/sq cm/s in the plasmasphere, while heating from the PSEs typically does not exceed 10(exp 8) eV/sq cm/s. On the nightside, the inner plasmasphere is usually unheated by superthermal electrons. A feature of these combined spectra is that the distribution often has upward slopes with energy, particularly at the crossover from PE to PSE dominance, indicating that instabilities are possible.

Currents and Flows in Distant Magnetospheres

NASA Technical Reports Server (NTRS)

Kivelson, Margaret Galland

2000-01-01

Space scientists have explored, described, and explained the terrestrial magnetosphere for four decades. Rarely do they point out that the planetary and solar wind parameters controlling the size, shape, and activity of Earth's magnetosphere map out only a small portion of the space of dimensionless parameters that govern magnetospheric properties. With the discovery of Ganymede's magnetosphere, the range of parameters relevant to magnetospheric studies has grown by orders of magnitude. Consider the extremes of Ganymede's and Jupiter's magnetospheres. Jupiter's magnetosphere forms within a plasma flowing at super-Alfvenic speed, whereas Ganymede's forms in a sub-Alfvenic flow. The scale sizes of these magnetospheres, characterized by distances to the magnetopause of order 7x10(exp 6) km and 5x10(exp 3) km, respectively, differ by three orders of magnitude, ranging from 100 to 0.1 times the scale of Earth's magnetosphere. The current systems that control the structure and dynamics of a magnetosphere depend on specific plasma and field properties. Magnetopause currents at Ganymede differ greatly from the forms familiar for Earth and Jupiter, principally because the Mach number of the ambient plasma flow greatly influences the shape of the magnetosphere. A magnetodisk current, present at Jupiter because of its rapid rotation, is absent at Earth and Ganymede. The ring current, extensively investigated at Earth, is probably unimportant at Ganymede because the dynamical variations of the external flow are slow. The ring current is subsumed within the magnetodisk current at Jupiter. This paper describes and contrasts aspects of these and other current systems for the three bodies.

Pressure balance inconsistency exhibited in a statistical model of magnetospheric plasma

NASA Astrophysics Data System (ADS)

Garner, T. W.; Wolf, R. A.; Spiro, R. W.; Thomsen, M. F.; Korth, H.

2003-08-01

While quantitative theories of plasma flow from the magnetotail to the inner magnetosphere typically assume adiabatic convection, it has long been understood that these convection models tend to overestimate the plasma pressure in the inner magnetosphere. This phenomenon is called the pressure crisis or the pressure balance inconsistency. In order to analyze it in a new and more detailed manner we utilize an empirical model of the proton and electron distribution functions in the near-Earth plasma sheet (-50 RE < X < -10 RE), which uses the [1989] magnetic field model and a plasma sheet representation based upon several previously published statistical studies. We compare our results to a statistically derived particle distribution function at geosynchronous orbit. In this analysis the particle distribution function is characterized by the isotropic energy invariant λ = EV2/3, where E is the particle's kinetic energy and V is the magnetic flux tube volume. The energy invariant is conserved in guiding center drift under the assumption of strong, elastic pitch angle scattering. If, in addition, loss is negligible, the phase space density f(λ) is also conserved along the same path. The statistical model indicates that f(λ, ?) is approximately independent of X for X ≤ -35 RE but decreases with increasing X for X ≥ -35 RE. The tailward gradient of f(λ, ?) might be attributed to gradient/curvature drift for large isotropic energy invariants but not for small invariants. The tailward gradient of the distribution function indicates a violation of the adiabatic drift condition in the plasma sheet. It also confirms the existence of a "number crisis" in addition to the pressure crisis. In addition, plasma sheet pressure gradients, when crossed with the gradient of flux tube volume computed from the [1989] magnetic field model, indicate Region 1 currents on the dawn and dusk sides of the outer plasma sheet.

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 (?)

Cassini/MIMI Measurements in Saturn's Magnetosphere and their Implications for Magnetospheric Dynamics

NASA Astrophysics Data System (ADS)

Mitchell, D. G.

2016-12-01

The Cassini spacecraft has been in orbit about Saturn since early July, 2004. In less than a year, on September 15, 2017, Cassini will plunge into Saturn's atmosphere, ending what has been a highly successful and interesting mission. As befitting a Planetary Division Flagship Mission, Cassini's science payload included instrumentation designed for a multitude of science objectives, from surfaces of moons to rings to atmospheres to Saturn's vast, fast-rotating magnetosphere. Saturn's magnetosphere exhibits considerable variability, both from inner magnetosphere to outer, and over time. Characterizing the dynamics of the magnetosphere has required the full range of energetic particles (measured by the magnetospheric imaging instrument, MIMI - https://saturn.jpl.nasa.gov/magnetospheric-imaging-instrument/), plasma (provided by the Cassini plasma spectrometer, CAPS), gas (ion and neutral mass spectrometer, INMS), magnetic fields (Cassini magnetometer, MAG), radio and plasma waves (radio and plasma wave science, RPWS), dust (Cassini Dust Analyzer, CDA), as well as ultraviolet, visible and infrared imaging (ultraviolet imaging spectrograph, UVIS; Cassini imaging subsystem ISS; visible and infrared mapping spectrometer, VIMS; Cassini composite infrared spectrometer, CIRS) and ionospheric sounding by the Cassini radio science subsystem (RSS). It has also required the full range of orbital geometries from equatorial to high inclination and all local times, as well as the full range of solar wind conditions, seasonal sun-Saturn configurations. In this talk we focus on the contributions of the MIMI instrument suite (CHEMS, LEMMS, and INCA) to our understanding of the dynamics of Saturn's magnetosphere. We will both review past work, and present recent observations from the high inclination orbits that precede the final stages of the Cassini mission, the sets of high inclination orbits that cross the equator just beyond the edge of the main ring system, and later cross between

Statistical study of phase relationships between magnetic and plasma thermal pressures in the near-earth magnetosphere using the THEMIS satellites

NASA Astrophysics Data System (ADS)

Nishi, K.; Kazuo, S.

2017-12-01

The auroral finger-like structures appear in the equatorward part of the auroral oval in the diffuse auroral region, and contribute to the auroral fragmentation into patches during substorm recovery phase. In our previous presentations, we reported the first conjugate observation of auroral finger-like structures using the THEMIS GBO cameras and the THEMIS satellites, which was located at a radial distance of 9 Re in the dawnside plasma sheet. In this conjugate event, we found anti-phase fluctuation of plasma pressure and magnetic pressure with a time scale of 5-20 min in the plasma sheet. This observational fact is consistent with the idea that the finger-like structures are caused by a pressure-driven instability in the balance of plasma and magnetic pressures in the magnetosphere. Then we also searched simultaneous observation events of auroral finger-like structures with the RBSP satellites which have an apogee of 5.8 Re in the inner magnetosphere. Contrary to the first result, the observed variation of plasma and magnetic pressures do not show systematic phase relationship. In order to investigate these phase relationships between plasma and magnetic pressures in the magnetosphere, we statistically analyzed these pressure data using the THEMIS-E satellite for one year in 2011. In the preliminary analysis of pressure variation spectra, we found that out of phase relationship between magnetic and plasma pressures occupied 40 % of the entire period of study. In the presentation, we will discuss these results in the context of relationships between the pressure fluctuations and the magnetospheric instabilities that can cause auroral finger-like structures.

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.

Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

NASA Technical Reports Server (NTRS)

Sittler, E.; Cooper, J.; Hartle, R.; Simpson, D.; Johnson, R.; Thomsen, M.; Arridge, C.

2011-01-01

We present the present status of an investigation of the rotation rate of Saturn's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. for SOI and similar to that used by Thomsen et al.. This technique allows one to nearly cover the full energy range of the Cassini Plasma Spectrometer (CAPS) IMS from 1 V . E/Q < 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll maneuvers. We make comparisons with the bi-Maxwellian fitting technique developed by Wilson et al. and the similar velocity moment technique by Thomsen et al. . We concentrate our analysis when ion composition data is available, which is used to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The chosen periods have high enough telemetry rates (4 kbps or higher) so that coincidence ion data, similar to that used by Sittler et al. for SOI is available. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. In the future we will then make comparisons with magnetic field observations, Saturn ionosphere conductivities as presently known and the field aligned currents necessary for the planet to enforce corotation of the rotating plasma.

Titan Ion Composition at Magnetosphere-Ionosphere Transition Region

NASA Technical Reports Server (NTRS)

Sittler, Edward C.; Hartle, R. E.; Shappirio, M.; Simpson, D. J.; COoper, J. F.; Burger, M. H.; Johnson, R. E.; Bertucci, C.; Luhman, J. G.; Ledvina, S. A.;

Coupled low-energy - ring current plasma diffusion in the Jovian magnetosphere

NASA Technical Reports Server (NTRS)

Summers, D.; Siscoe, G. L.

1985-01-01

The outwardly diffusing Iogenic plasma and the simultaneously inwardly diffusing ring current plasma in the Jovian magnetosphere are described using a coupled diffusion model which incorporates the effects of the pressure gradient of the ring current into the cross-L diffusion coefficient. The coupled diffusion coefficient is derived by calculating the total energy available to drive the diffusion process. The condition is imposed that the diffusion coefficient takes on a local minimum value at some point in the region L = 7-8, at which point the gradient of the Io plasma density is specified as ramp value given by Siscoe et al. (1981). The hypothesis that the pressure gradient of the ring current causes the diminution of radial plasma transport is tested, and solution profiles for the Iogenic and ring current plasma densities are obtained which imply that the Io plasma ramp is caused by a high-density, low-energy component of the ring current hitherto unobserved directly.

Control of ULF Wave Accessibility to the Inner Magnetosphere by the Convection of Plasma Density

NASA Astrophysics Data System (ADS)

Degeling, A. W.; Rae, I. J.; Watt, C. E. J.; Shi, Q. Q.; Rankin, R.; Zong, Q.-G.

2018-02-01

During periods of storm activity and enhanced convection, the plasma density in the afternoon sector of the magnetosphere is highly dynamic due to the development of plasmaspheric drainage plume (PDP) structure. This significantly affects the local Alfvén speed and alters the propagation of ULF waves launched from the magnetopause. Therefore, it can be expected that the accessibility of ULF wave power for radiation belt energization is sensitively dependent on the recent history of magnetospheric convection and the stage of development of the PDP. This is investigated using a 3-D model for ULF waves within the magnetosphere in which the plasma density distribution is evolved using an advection model for cold plasma, driven by a (VollandStern) convection electrostatic field (resulting in PDP structure). The wave model includes magnetic field day/night asymmetry and extends to a paraboloid dayside magnetopause, from which ULF waves are launched at various stages during the PDP development. We find that the plume structure significantly alters the field line resonance location, and the turning point for MHD fast waves, introducing strong asymmetry in the ULF wave distribution across the noon meridian. Moreover, the density enhancement within the PDP creates a waveguide or local cavity for MHD fast waves, such that eigenmodes formed allow the penetration of ULF wave power to much lower L within the plume than outside, providing an avenue for electron energization.

Physics of Magnetospheric Variability

NASA Astrophysics Data System (ADS)

Vasyliūnas, Vytenis M.

2011-01-01

Many widely used methods for describing and understanding the magnetosphere are based on balance conditions for quasi-static equilibrium (this is particularly true of the classical theory of magnetosphere/ionosphere coupling, which in addition presupposes the equilibrium to be stable); they may therefore be of limited applicability for dealing with time-variable phenomena as well as for determining cause-effect relations. The large-scale variability of the magnetosphere can be produced both by changing external (solar-wind) conditions and by non-equilibrium internal dynamics. Its developments are governed by the basic equations of physics, especially Maxwell's equations combined with the unique constraints of large-scale plasma; the requirement of charge quasi-neutrality constrains the electric field to be determined by plasma dynamics (generalized Ohm's law) and the electric current to match the existing curl of the magnetic field. The structure and dynamics of the ionosphere/magnetosphere/solar-wind system can then be described in terms of three interrelated processes: (1) stress equilibrium and disequilibrium, (2) magnetic flux transport, (3) energy conversion and dissipation. This provides a framework for a unified formulation of settled as well as of controversial issues concerning, e.g., magnetospheric substorms and magnetic storms.

Self-consistent electrostatic potential due to trapped plasma in the magnetosphere

NASA Technical Reports Server (NTRS)

Miller, Ronald H.; Khazanov, George V.

1993-01-01

A steady state solution for the self-consistent electrostatic potential due to a plasma confined in a magnetic flux tube is considered. A steady state distribution function is constructed for the trapped particles from the constants of the motion, in the absence of waves and collisions. Using Liouville's theorem, the particle density along the geomagnetic field is determined and found to depend on the local magnetic field, self-consistent electric potential, and the equatorial plasma distribution function. A hot anisotropic magnetospheric plasma in steady state is modeled by a bi-Maxwellian at the equator. The self-consistent electric potential along the magnetic field is calculated assuming quasineutrality, and the potential drop is found to be approximately equal to the average kinetic energy of the equatorially trapped plasma. The potential is compared with that obtained by Alfven and Faelthammar (1963).

Unresolved Issues With Inner Magnetosphere-Ionosphere Coupling

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Khazanov, G.

2004-01-01

Dipolarization and the release of stored magnetic energy is strongly evident in the energized plasma sheet electrons and ions injected earthward from the magnetotail. While some of these plasma are presumed lost into the dayside magnetosheath, much of the energy is dissipated into the ionosphere through electric currents, through collisions into low energy plasma, and into plasma waves, which then go on to heat and energize plasma of the inner magnetosphere. Many mechanisms for the transfer of energy and the consequences to inner magnetospheric plasma populations have been proposed. The sophistication of theoretical models to represent the interdependencies between plasma populations is rapidly increasing. However without the restraint and reality imposed on theory by relevant measurements, the degree to which specific mechanisms participate in the exchange of energy as a function of location and time cannot be known. ORBITALS offers this capability. Some of the outstanding problems in inner magnetospheric physics and the opportunities presented by the ORBITAL concept to solve problems will be discussed.

Radial energy transport by magnetospheric ULF waves: Effects of magnetic curvature and plasma pressure

NASA Technical Reports Server (NTRS)

Kouznetsov, Igor; Lotko, William

1995-01-01

The 'radial' transport of energy by internal ULF waves, stimulated by dayside magnetospheric boundary oscillations, is analyzed in the framework of one-fluid magnetohydrodynamics. (the term radial is used here to denote the direction orthogonal to geomagnetic flux surfaces.) The model for the inhomogeneous magnetospheric plasma and background magnetic field is axisymmetric and includes radial and parallel variations in the magnetic field, magnetic curvature, plasma density, and low but finite plasma pressure. The radial mode structure of the coupled fast and intermediate MHD waves is determined by numerical solution of the inhomogeneous wave equation; the parallel mode structure is characterized by a Wentzel-Kramer-Brillouin (WKB) approximation. Ionospheric dissipation is modeled by allowing the parallel wave number to be complex. For boudnary oscillations with frequencies in the range from 10 to 48 mHz, and using a dipole model for the background magnetic field, the combined effects of magnetic curvature and finite plasma pressure are shown to (1) enhance the amplitude of field line resonances by as much as a factor of 2 relative to values obtained in a cold plasma or box-model approximation for the dayside magnetosphere; (2) increase the energy flux delivered to a given resonance by a factor of 2-4; and (3) broaden the spectral width of the resonance by a factor of 2-3. The effects are attributed to the existence of an 'Alfven buoyancy oscillation,' which approaches the usual shear mode Alfven wave at resonance, but unlike the shear Alfven mode, it is dispersive at short perpendicular wavelengths. The form of dispersion is analogous to that of an internal atmospheric gravity wave, with the magnetic tension of the curved background field providing the restoring force and allowing radial propagation of the mode. For nominal dayside parameters, the propagation band of the Alfven buoyancy wave occurs between the location of its (field line) resonance and that of the

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?

The mirage of Mars magnetosphere

NASA Astrophysics Data System (ADS)

Mordovskaya, V.

The spacecraft Phobos 2 has been on the circular orbit around Mars at the distance of 2 Mars's radiuses for a whole month. There are a lot of data and so we can speak about some statistics. The dependence of the perturbed magnetic field in the Mars wake on the density of the ambient solar wind plasma is traced but the same dependence from the velocity is absent. The picture of the solar wind interaction with Martian obstacle is not typical for magnetosphere. For high plasma density the value of the perturbed magnetic field in the wake of Mars and its size increase considerably and the perturbed region swells. The magnetosphere of Earth is compressed in the same cases. This points out that Mars has the weak protective magnetic screen. The estimation of its size gives the value about 160-220 km. Because of the lack of the protective magnetic screen, it seems, the solar wind with the density lower than 1 cm-3 interacts with the Martian atmosphere directly. The density of the ambient plasma is usually about 1 cm-3 and the thickness of the skin layers exceeds the scale of the Martian protective magnetic screen, the field freely passes over. The magnetosphere of Mars "disappears". The existence of the regions of the rarefied plasma behind Mars, due to a shading of particles of the solar wind plasma is an argument in favors of the disappearance of the Martian magnetosphere.

Inner Magnetospheric Physics

NASA Technical Reports Server (NTRS)

Gallagher, Dennis

2018-01-01

Outline - Inner Magnetosphere Effects: Historical Background; Main regions and transport processes: Ionosphere, Plasmasphere, Plasma sheet, Ring current, Radiation belt; Geomagnetic Activity: Storms, Substorm; Models.

Instrument technology for magnetosphere plasma imaging from high Earth orbit. Design of a radio plasma sounder

NASA Technical Reports Server (NTRS)

Haines, D. Mark; Reinisch, Bodo W.

1995-01-01

The use of radio sounding techniques for the study of the ionospheric plasma dates back to G. Briet and M. A. Tuve in 1926. Ground based swept frequency sounders can monitor the electron number density (N(sub e)) as a function of height (the N(sub e) profile). These early instruments evolved into a global network that produced high-resolution displays of echo time delay vs frequency on 35-mm film. These instruments provided the foundation for the success of the International Geophysical Year (1958). The Alouette and International Satellites for Ionospheric Studies (ISIS) programs pioneered the used of spaceborne, swept frequency sounders to obtain N(sub e) profiles of the topside of the ionosphere, from a position above the electron density maximum. Repeated measurements during the orbit produced an orbital plane contour which routinely provided density measurements to within 10%. The Alouette/ISIS experience also showed that even with a high powered transmitter (compared to the low power sounder possible today) a radio sounder can be compatible with other imaging instruments on the same satellite. Digital technology was used on later spacecraft developed by the Japanese (the EXOS C and D) and the Soviets (Intercosmos 19 and Cosmos 1809). However, a full coherent pulse compression and spectral integrating capability, such as exist today for ground-based sounders (Reinisch et al., 1992), has never been put into space. NASA's 1990 Space Physics Strategy Implementation Study "The NASA Space Physics Program from 1995 to 2010" suggested using radio sounders to study the plasmasphere and the magnetopause and its boundary layers (Green and Fung, 1993). Both the magnetopause and plasmasphere, as well as the cusp and boundary layers, can be observed by a radio sounder in a high-inclination polar orbit with an apogee greater than 6 R(sub e) (Reiff et al., 1994; Calvert et al., 1995). Magnetospheric radio sounding from space will provide remote density measurements of

Magnetospheric Multiscale (MMS)

NASA Image and Video Library

2017-12-08

MMS Spacecraft Animation The Magnetospheric Multiscale (MMS) mission is a Solar Terrestrial Probes mission comprising four identically instrumented spacecraft that will use Earth's magnetosphere as a laboratory to study the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence. These processes occur in all astrophysical plasma systems but can be studied in situ only in our solar system and most efficiently only in Earth's magnetosphere, where they control the dynamics of the geospace environment and play an important role in the processes known as "space weather." Learn more about MMS at www.nasa.gov/mms Learn more about MMS at www.nasa.gov/mms Credit NASA/Chris Gunn The Magnetospheric Multiscale, or MMS, will study how the sun and the Earth's magnetic fields connect and disconnect, an explosive process that can accelerate particles through space to nearly the speed of light. This process is called magnetic reconnection and can occur throughout all space. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Ionospheric Outflow in the Magnetosphere: Circulation and Consequences

NASA Astrophysics Data System (ADS)

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

2017-12-01

Including ionospheric outflow in global magnetohydrodynamic models of near-Earth outer space has become an important step towards understanding the role of this plasma source in the magnetosphere. Such simulations have revealed the importance of outflow in populating the plasma sheet and inner magnetosphere as a function of outflow source characteristics. More importantly, these experiments have shown how outflow can control global dynamics, including tail dynamics and dayside reconnection rate. The broad impact of light and heavy ion outflow can create non-linear feedback loops between outflow and the magnetosphere. This paper reviews some of the most important revelations from global magnetospheric modeling that includes ionospheric outflow of light and heavy ions. It also introduces new advances in outflow modeling and coupling outflow to the magnetosphere.

Mini-Magnetospheres at the Moon in the Solar Wind and the Earth's Plasma Sheet

NASA Astrophysics Data System (ADS)

Harada, Y.; Futaana, Y.; Barabash, S. V.; Wieser, M.; Wurz, P.; Bhardwaj, A.; Asamura, K.; Saito, Y.; Yokota, S.; Tsunakawa, H.; Machida, S.

2014-12-01

Lunar mini-magnetospheres are formed as a consequence of solar-wind interaction with remanent crustal magnetization on the Moon. A variety of plasma and field perturbations have been observed in a vicinity of the lunar magnetic anomalies, including electron energization, ion reflection/deflection, magnetic field enhancements, electrostatic and electromagnetic wave activities, and low-altitude ion deceleration and electron acceleration. Recent Chandrayaan-1 observations of the backscattered energetic neutral atoms (ENAs) from the Moon in the solar wind revealed upward ENA flux depletion (and thus depletion of the proton flux impinging on the lunar surface) in association with strongly magnetized regions. These ENA observations demonstrate that the lunar surface is shielded from the solar wind protons by the crustal magnetic fields. On the other hand, when the Moon was located in the Earth's plasma sheet, no significant depletion of the backscattered ENA flux was observed above the large and strong magnetic anomaly. It suggests less effective magnetic shielding of the surface from the plasma sheet protons than from the solar wind protons. We conduct test-particle simulations showing that protons with a broad velocity distribution are more likely to reach a strongly magnetized surface than those with a beam-like velocity distribution. The ENA observations together with the simulation results suggest that the lunar crustal magnetic fields are no longer capable of standing off the ambient plasma when the Moon is immersed in the hot magnetospheric plasma.

The Earth's magnetosphere as a sample of the plasma universe

NASA Technical Reports Server (NTRS)

Faelthammar, Carl-Gunne

1986-01-01

Plasma processes in the Earth's neighborhood determine the environmental conditions under which space-based equipment for science or technology must operate. These processes are peculiar to a state of matter that is rare on Earth but dominates the universe as whole. The physical, and especially the electrodynamic, properties of this state of matter is still far from well understood. By fortunate circumstances, the magnetosphere-ionosphere system of the Earth provides a rich sample of widely different plasma populations, and, even more importantly, it is the site of a remarkable variety of plasma processes. In different combinations such processes must be important throughout the universe, which is overwhelmingly dominated by matter in the plasma state. Therefore, observations and experiments in the near-Earth plasma serve a multitude of purposes. They will not only (1) clarify the dynamics of the space environment but also (2) widen the understanding of matter, (3) form a basis for interpretating remote observations of astrophysical objects, thereby even (4) help to reconstruct events that led to the evolution of the solar system. Last but not least they will (5) provide know-how required for adapting space-based technology to the plasma environment. Such observations and experiments will require a close mutual interplay between science and technology.

The Effect of Background Plasma Temperature on Growth and Damping of Whistler Mode Wave Power in the Earth's Magnetosphere

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; Malaspina, D.; Jaynes, A. N.

2017-12-01

Whistler mode waves play a dominant role in the energy dynamics of the Earth's magnetosphere. Trajectory of whistler mode waves can be predicted by raytracing. Raytracing is a numerical method which solves the Haselgrove's equations at each time step taking the background plasma parameters in to account. The majority of previous raytracing work was conducted assuming a cold (0 K) background magnetospheric plasma. Here we perform raytracing in a finite temperature plasma with background electron and ion temperatures of a few eV. When encountered with a high energy (>10 keV) electron distribution, whistler mode waves can undergo a power attenuation and/or growth, depending on resonance conditions which are a function of wave frequency, wave normal angle and particle energy. In this work we present the wave power attenuation and growth analysis of whistler mode waves, during the interaction with a high energy electron distribution. We have numerically modelled the high energy electron distribution as an isotropic velocity distribution, as well as an anisotropic bi-Maxwellian distribution. Both cases were analyzed with and without the temperature effects for the background magnetospheric plasma. Finally we compare our results with the whistler mode energy distribution obtained by the EMFISIS instrument hosted at the Van Allen Probe spacecraft.

Effect of tail plasma sheet conditions on the penetration of the convection electric field in the inner magnetosphere: RCM simulations with self-consistent magnetic field

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Wang, C.; Lyons, L. R.; Wolf, R.

2009-12-01

Transport of plasma sheet particles into the inner magnetosphere is strongly affected by the penetration of the convection electric field, which is the result of the large-scale magnetosphere ionosphere electromagnetic coupling. This transport, on the other hand, results in plasma heating and magnetic field stretching, which become very significant in the inner plasma sheet (inside 20 RE). We have previously run simulations with the Rice Convection Model (RCM), using the Tsyganenko 96 magnetic field model, to investigate how the earthward penetration of electric field depends on plasma sheet conditions. Outer proton and electron sources at r ~20 RE, are based on 11 years of Geotail data, and realistically represent the mixture of cold and hot plasma sheet population as a function of MLT and interplanetary conditions. We found that shielding of the inner magnetosphere electric field is more efficient for a colder and denser plasma sheet, which is found following northward IMF, than for the hotter and more tenuous plasma sheet found following southward IMF. Our simulation results so far indicate further earthward penetration of plasma sheet particles in response to enhanced convection if the preceding IMF is southward, which leads to weaker electric field shielding. Recently we have integrated the RCM with a magnetic field solver to obtain magnetic fields that are in force balance with given plasma pressures in the equatorial plane. We expect the self-consistent magnetic field to have a pronounced dawn dusk asymmetry due to the asymmetric inner magnetospheric pressure. This should affect the radial distance and MLT of plasma sheet penetration into the inner magnetosphere. We are currently using this force-balanced and self-consistent model with our realistic boundary conditions to evaluate the dependence of the shielding timescale on pre-existing plasma sheet number density and temperature and to more quantitatively determine the correlation between the plasma sheet

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.

The magnetosphere of Neptune - Its response to daily rotation

NASA Technical Reports Server (NTRS)

Voigt, Gerd-Hannes; Ness, Norman F.

1990-01-01

The Neptunian magnetosphere periodically changes every eight hours between a pole-on magnetosphere with only one polar cusp and an earth-type magnetosphere with two polar cusps. In the pole-on configuration, the tail current sheet has an almost circular shape with plasma currents closing entirely within the magnetosphere. Eight hours later the tail current sheet assumes an almost flat shape with plasma currents touching the magnetotail boundary and closing over the tail magnetopause. Magnetic field and tail current sheet configurations have been calculated in a three-dimensional model, but the plasma- and thermodynamic conditions were investigated in a simplified two-dimensional MHD equilibrium magnetosphere. It was found that the free energy in the tail region of the two-dimensional model becomes independent of the dipole tilt angle. It is conjectured that the Neptunian magnetotail might assume quasi-static equilibrium states that make the free energy of the system independent of its daily rotation.

Plasma Entry from Tail into the Dipolar Magnetosphere During Substorms

NASA Astrophysics Data System (ADS)

Haerendel, Gerhard

Plasma entering the dipolar magnetosphere from the tail has to overcome the obstacle presented by the conductivity enhancements caused by the poleward arc(s). While the arcs move poleward, the plasma proceeds equatorward as testified by the existence of a westward electric field. The arcs break into smaller-scale structures and loops with a tendency of eastward growth and expansion, although the basic driving force is directed earthward/equatorward. The likely reason is that the arc-related conductivity enhancements act as flow barriers and convert normal into shear stresses. The energy derived from the release of the shear stresses and dissipated in the arcs lowers the entropy content of the flux tubes and enables their earthward progression. In addition, poleward jumps of the breakup arcs are quite common. They result from refreshments of the generator plasma by the sequential arrival of flow bursts from the near-Earth neutral line. Once inside the oval, the plasma continues to move equatorward as manifested through north-south aligned auroral forms. Owing to the existence of an inner border of the oval, marked by the Region 2 currents, all flows are eventually diverted sunward.

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.

AMPS sciences objectives and philosophy. [Atmospheric, Magnetospheric and Plasmas-in-Space project on Spacelab

NASA Technical Reports Server (NTRS)

Schmerling, E. R.

1975-01-01

The Space Shuttle will open a new era in the exploration of earth's near-space environment, where the weight and power capabilities of Spacelab and the ability to use man in real time add important new features. The Atmospheric, Magnetospheric, and Plasmas-in-Space project (AMPS) is conceived of as a facility where flexible core instruments can be flown repeatedly to perform different observations and experiments. The twin thrusts of remote sensing of the atmosphere below 120 km and active experiments on the space plasma are the major themes. They have broader implications in increasing our understanding of plasma physics and of energy conversion processes elsewhere in the universe.

Concepts of magnetospheric convection

NASA Technical Reports Server (NTRS)

Vasyliunas, V. M.

1975-01-01

The paper describes the basic theoretical notions of convection applicable to magnetospheres in general and discusses the relative importance of convective and corrotational motions, with particular reference to the comparison of the earth and Jupiter. The basic equations relating the E, B, and J fields and the bulk plasma velocity are given for the three principal regions in magnetosphere dynamics, namely, the central object and its magnetic field, the space surrounding the central object, and the external medium outside the magnetosphere. The notion of driving currents of magnetospheric convection and their closure is explained, while consideration of the added effects of the rotation of the central body completes the basic theoretical picture. Flow topology is examined for the two cases where convection dominates over corotation and vice versa.

Magnetosphere imager science definition team: Executive summary

NASA Technical Reports Server (NTRS)

Armstrong, T. P.; Gallagher, D. L.; Johnson, C. L.

1995-01-01

For three decades, magnetospheric field and plasma measurements have been made by diverse instruments flown on spacecraft in many different orbits, widely separated in space and time, and under various solar and magnetospheric conditions. Scientists have used this information to piece together an intricate, yet incomplete view of the magnetosphere. A simultaneous global view, using various light wavelengths and energetic neutral atoms, could reveal exciting new data and help explain complex magnetospheric processes, thus providing a clear picture of this region of space. This report summarizes the scientific rationale for such a magnetospheric imaging mission and outlines a mission concept for its implementation.

Magnetosphere imager science definition team interim report

NASA Technical Reports Server (NTRS)

Armstrong, T. P.; Johnson, C. L.

1995-01-01

For three decades, magnetospheric field and plasma measurements have been made by diverse instruments flown on spacecraft in may different orbits, widely separated in space and time, and under various solar and magnetospheric conditions. Scientists have used this information to piece together an intricate, yet incomplete view of the magnetosphere. A simultaneous global view, using various light wavelengths and energetic neutral atoms, could reveal exciting new data nd help explain complex magnetospheric processes, thus providing a clear picture of this region of space. This report documents the scientific rational for such a magnetospheric imaging mission and provides a mission concept for its implementation.

Magnetospheric Multiscale (MMS) [video

NASA Image and Video Library

2014-05-09

MMS Spacecraft Animation The Magnetospheric Multiscale (MMS) mission is a Solar Terrestrial Probes mission comprising four identically instrumented spacecraft that will use Earth's magnetosphere as a laboratory to study the microphysics of three fundamental plasma processes: magnetic reconnection, energetic particle acceleration, and turbulence. These processes occur in all astrophysical plasma systems but can be studied in situ only in our solar system and most efficiently only in Earth's magnetosphere, where they control the dynamics of the geospace environment and play an important role in the processes known as "space weather." Learn more about MMS at www.nasa.gov/mms Learn more about MMS at www.nasa.gov/mms Credit NASA/Goddard The Magnetospheric Multiscale, or MMS, will study how the sun and the Earth's magnetic fields connect and disconnect, an explosive process that can accelerate particles through space to nearly the speed of light. This process is called magnetic reconnection and can occur throughout all space. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Electromagnetic radiation trapped in the magnetosphere above the plasma frequency

NASA Technical Reports Server (NTRS)

Gurnett, D. A.; Shaw, R. R.

1973-01-01

An electromagnetic noise band is frequently observed in the outer magnetosphere by the Imp 6 spacecraft at frequencies from about 5 to 20 kHz. This noise band generally extends throughout the region from near the plasmapause boundary to near the magnetopause boundary. The noise typically has a broadband field strength of about 5 microvolts/meter. The noise band often has a sharp lower cutoff frequency at about 5 to 10 kHz, and this cutoff has been identified as the local electron plasma frequency. Since the plasma frequency in the plasmasphere and solar wind is usually above 20 kHz, it is concluded that this noise must be trapped in the low-density region between the plasmapause and magnetopause boundaries. The noise bands often contain a harmonic frequency structure which suggests that the radiation is associated with harmonics of the electron cyclotron frequency.

Magnetospheric Multiscale Observation of Plasma Velocity-Space Cascade: Hermite Representation and Theory.

PubMed

Servidio, S; Chasapis, A; Matthaeus, W H; Perrone, D; Valentini, F; Parashar, T N; Veltri, P; Gershman, D; Russell, C T; Giles, B; Fuselier, S A; Phan, T D; Burch, J

2017-11-17

Plasma turbulence is investigated using unprecedented high-resolution ion velocity distribution measurements by the Magnetospheric Multiscale mission (MMS) in the Earth's magnetosheath. This novel observation of a highly structured particle distribution suggests a cascadelike process in velocity space. Complex velocity space structure is investigated using a three-dimensional Hermite transform, revealing, for the first time in observational data, a power-law distribution of moments. In analogy to hydrodynamics, a Kolmogorov approach leads directly to a range of predictions for this phase-space transport. The scaling theory is found to be in agreement with observations. The combined use of state-of-the-art MMS data sets, novel implementation of a Hermite transform method, and scaling theory of the velocity cascade opens new pathways to the understanding of plasma turbulence and the crucial velocity space features that lead to dissipation in plasmas.

Turbulent mass transfer caused by vortex induced reconnection in collisionless magnetospheric plasmas.

PubMed

Nakamura, T K M; Hasegawa, H; Daughton, W; Eriksson, S; Li, W Y; Nakamura, R

2017-11-17

Magnetic reconnection is believed to be the main driver to transport solar wind into the Earth's magnetosphere when the magnetopause features a large magnetic shear. However, even when the magnetic shear is too small for spontaneous reconnection, the Kelvin-Helmholtz instability driven by a super-Alfvénic velocity shear is expected to facilitate the transport. Although previous kinetic simulations have demonstrated that the non-linear vortex flows from the Kelvin-Helmholtz instability gives rise to vortex-induced reconnection and resulting plasma transport, the system sizes of these simulations were too small to allow the reconnection to evolve much beyond the electron scale as recently observed by the Magnetospheric Multiscale (MMS) spacecraft. Here, based on a large-scale kinetic simulation and its comparison with MMS observations, we show for the first time that ion-scale jets from vortex-induced reconnection rapidly decay through self-generated turbulence, leading to a mass transfer rate nearly one order higher than previous expectations for the Kelvin-Helmholtz instability.

On the Magnetospheric Heating Problem

NASA Astrophysics Data System (ADS)

Nykyri, K.; Moore, T.; Dimmock, A. P.; Ma, X.; Johnson, J.; Delamere, P. A.

2016-12-01

In the Earth's magnetosphere the specific entropy, increases by approximately two orders of magnitude when transitioning from the magnetosheath into the magnetosphere. However, the origin of this non-adiabatic heating is not well understood. In addition, there exists a dawn-dusk temperature asymmetry in the flanks of the plasma sheet - the cold component ions are hotter by 30-40% at the dawnside plasma sheet compared to the duskside plasma sheet. Our recent statistical study of magnetosheath temperatures using 7 years of THEMIS data indicates that ion magnetosheath temperatures downstream of quasi-parallel (dawn-flank for the Parker-Spiral IMF) bow shock are only 15 percent higher than downstream of the quasi-perpendicular shock. This magnetosheath temperature asymmetry is therefore inadequate to cause the observed level of the plasma sheet temperature asymmetry. In this presentation we address the origin of non-adiabatic heating from the magnetosheath into the plasma sheet by utilizing small Cluster spacecraft separations, 9 years of statistical THEMIS data as well as Hall-MHD and hybrid simulations. We present evidence of a new physical mechanism capable of cross-scale energy transport at the flank magnetopause with strong contributions to the non-adiabatic heating observed between the magnetosheath and plasma sheet. This same heating mechanism may occur and drive asymmetries also in the magnetospheres of gas giants: Jupiter and Saturn, as well as play role elsewhere in the universe where significant flow shears are present such as in the solar corona, and other astrophysical and laboratory plasmas.

Magnetospheric turbulence and substorm expansion phase onset

NASA Astrophysics Data System (ADS)

Antonova, Elizaveta; Stepanova, Marina; Kirpichev, Igor; Pulinets, Maria; Znatkova, Svetlana; Ovchinnikov, Ilya; Kornilov, Ilya; Kornilova, Tatyana

Magnetosphere of the Earth is formed in the process of turbulent solar wind flow around the obstacle -magnetic field of the Earth. The level of turbulence in the magnetosheath and geo-magnetic tail is very high even during periods of comparatively stable solar wind parameters. Such situation requires checking of the most popular concepts of the nature of magnetospheric activity. Properties of magnetosheath and magnetospheric turbulence are analyzed in connec-tion with the problem of the nature of substorms and localization of substorm onset. The large-scale picture of the plasma velocity fluctuations obtained using data of INTERBALL and Geotail observations is analyzed. It is shown that it is possible to select surrounding the Earth at geocentric distances from 7Re till 10Re plasma ring with comparatively low level of fluctuations. Results of observations demonstrating isolated substorm onset inside this ring are summarized. It is shown that the non-contradictory picture of large-scale magnetospheric convection and substorm dynamics can be obtained taking into account high level of magne-tosheath and magnetospheric turbulence.

Does Solar Wind also Drive Convection in Jupiter's Magnetosphere?

NASA Astrophysics Data System (ADS)

Khurana, K. K.

2001-05-01

Using a simple model of magnetic field and plasma velocity, Brice and Ioannidis [1970] showed that the corotation electric field exceeds convection electric field throughout the Jovian magnetosphere. Since that time it has been tacitly assumed that Jupiter's magnetosphere is driven from within. If Brice and Ioannidis conjecture is correct then one would not expect major asymmetries in the field and plasma parameters in the middle magnetosphere of Jupiter. Yet, new field and plasma observations from Galileo and simultaneous auroral observations from HST show that there are large dawn/dusk and day/night asymmetries in many magnetospheric parameters. For example, the magnetic observations show that a partial ring current and an associated Region-2 type field-aligned current system exist in the magnetosphere of Jupiter. In the Earth's magnetosphere it is well known that the region-2 current system is created by the asymmetries imposed by a solar wind driven convection. Thus, we are getting first hints that the solar wind driven convection is important in Jupiter's magnetosphere as well. Other in-situ observations also point to dawn-dusk asymmetries imposed by the solar wind. For example, first order anisotropies in the Energetic Particle Detector show that the plasma is close to corotational on the dawn side but lags behind corotation in the dusk sector. Magnetic field data show that the current sheet is thin and highly organized on the dawn side but thick and disturbed on the dusk side. I will discuss the reasons why Brice and Ioannidis calculation may not be valid. I will show that both the magnetic field and plasma velocity estimates used by Brice and Ioannidis were rather excessive. Using more modern estimates of the field and velocity values I show that the solar wind convection can penetrate as deep as 40 RJ on the dawnside. I will present a new model of convection that invokes in addition to a distant neutral line spanning the whole magnetotail, a near

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.

Developing a global model of magnetospheric substorms

NASA Astrophysics Data System (ADS)

Kan, J. R.

1990-09-01

Competing models of magnetospheric substorms are discussed. The definitions of the three substorm phases are presented, and the advantages and drawbacks of the near-earth X-line model, magnetosphere-ionosphere coupling model, low-latitude boundary layer model, and thermal catastrophe model are examined. It is shown that the main challenge to achieving a quantitative understanding of the magnetospheric signatures of substorms is to understand the anomalous dissipation processes in collisionless plasmas.

AXIOM: Advanced X-ray Imaging of the Magnetosphere

NASA Technical Reports Server (NTRS)

Branduardi-Raymont, G.; Sembay, S. F.; Eastwood, J. P.; Sibeck, D. G.; Abbey, A.; Brown, P.; Carter, J. A.; Carr, C. M.; Forsyth, C.; Kataria, D.;

AXIOM: Advanced X-Ray Imaging of the Magnetosphere

NASA Technical Reports Server (NTRS)

Branduardi-Raymont, G.; Sembay, S. F.; Eastwood, J. P.; Sibeck, D. G.; Abbey, A.; Brown, P.; Carter, J. A.; Carr, C. M.; Forsyth, C.; Kataria, D.;

The Return of Magnetic Flux to the Inner Saturnian Magnetosphere

NASA Astrophysics Data System (ADS)

Lai, Hairong; Russell, Christopher T.; Jia, Yingdong; Masters, Adam; Dougherty, Michele K.

2017-04-01

The addition of plasma to the rotating inner Saturnian magnetosphere drives the circulation of the magnetic flux. The magnetic flux is loaded with cold plasma originating from Enceladus and its plasma torus. It then convects outward to the tail region, is emptied of plasma during reconnection events, and returns buoyantly to the inner magnetosphere. Returning flux tubes carry hot and tenuous plasma that serves as a marker of this type of flux tube. The plasma inside the tubes drifts at different rates depending on energy in the curved and inhomogeneous magnetosphere when the tubes convect inward. This energy dispersion can be used to track the flux tube. With data from MAG and CAPS, we model the energy dispersion of the electrons to determine the age and the point of return of the 'empty' flux tubes. The results show that even the 'fresh' flux tubes are several hours old when seen and they start to return at 19 Saturn radii, near Titan's orbit. This supports the hypothesis that returning flux tubes generated by reconnection in the far-tail region are injected directly into the inner magnetosphere.

Differential drift of plasma clouds in the magnetosphere: an update

NASA Astrophysics Data System (ADS)

Lemaire, J. F.

2001-07-01

First, Brice's (Journal of Geophysical Research 72 (1967) 5193) original theory for the formation of the plasmapause is recalled. Next, the motivation for writing a modification to this early theory is pointed out. The key aspects of Brice's manuscript are outlined and discussed. The mechanism of interchange driven by gravitational forces, centrifugal effects and kinetic pressure is considered in the cases when the integrated Pedersen conductivity is (i) negligibly small (as in Chandrasekhar's, Plasma Physics, University of Chicago Press, Chicago, 1960, 217 pp. and Longmire's, Elementary Plasma Physics, Wiley Interscience, New York, 1963, 296 pp., textbooks), (ii) infinitely large (as in many magnetospheric convection models), or (iii) has a finite value of the order of 0.2 mho, as in the Earth's ionosphere. Updates of this theory of interchange resulting from the existence of weak double layers, from quasi-interchange, or from the effects of an additional population of energetic ring-current particles forming the extended tail of the velocity distribution function, have also been reexamined.

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.

Wave particle interactions in Jupiter's magnetosphere: Implications for auroral and magnetospheric particle distributions

NASA Astrophysics Data System (ADS)

Saur, Joachim; Schreiner, Anne; Barry, Mauk; Clark, George; Kollman, Peter

2017-04-01

We investigate the occurrence and the role of wave particle interaction processes, i.e., Landau and cyclotron damping, in Jupiter's magnetosphere. Therefore we calculate kinetic length and temporal scales, which we cross-compare at various regions within Jupiter's magnetosphere. Based on these scales, we investigate the roles of possible wave particle mechanisms in each region, e.g., Jupiter's plasma sheet, the auroral acceleration region and the polar ionosphere. We thereby consider that the magnetospheric regions are coupled through convective transport, Alfven and other wave modes. We particularly focus on the role of kinetic Alfven waves in contributing to Jupiter's aurora. Our results will aid the interpretation of particle distribution functions measured by the JEDI instrument onboard the JUNO spacecraft.

Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

NASA Astrophysics Data System (ADS)

Horton, W.; Ditmire, T.; Zakharov, Yu. P.

2010-06-01

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

Seasonal variation and dynamics of Saturn's magnetospheric plasma, after 8 years of Cassini in orbit.

NASA Astrophysics Data System (ADS)

Sergis, N.

2012-12-01

Saturn orbits the Sun with a period of nearly 29.5 years and has an obliquity of 26.73°. As a result, Saturn presents seasonal variations similar to Earth's, but with much longer seasons, as the tilt between the planet's spin axis and the solar wind vary (approximately sinusoidally) with time between solstices. Saturn was close to its equinox (tilt below 8.1°) during the Pioneer 11 and Voyager 1 and 2 flybys that took place between September 1979 and August 1981, so any seasonal effects would have been relatively hard to see in the limited data from these missions. More than 2 decades later, on July 4, 2004, Cassini began orbiting Saturn, returning a variety of in situ and remote measurements. During the last 8 years, Cassini covered a large part of the Saturnian system and offered the opportunity of sampling the planetary magnetosphere not just at different seasons, but also at seasonal phases that are symmetric to the Saturnian equinox (August 2009). In this talk, we focus on the seasonal effects seen in the magnetosphere of Saturn as the angle between the solar wind flow and the Saturn-Sun direction changes from +23.7° (northern hemisphere winter) at the arrival of Cassini, to -14.9° (northern hemisphere summer) on July 2012. Particle and magnetic field data taken from a extensive set of equatorial and high latitude orbits of Cassini, at various distances and local times, show that: (a) the plasma sheet of Saturn has the form of a magnetodisk, with an energy-dependent vertical structure, being thicker by a factor of ~2 in the energetic particle range than in the electron plasma, and (b) it exhibits intense dynamical behavior, evident in in-situ particle measurements but also in energetic neutral atom (ENA) emissions. The study of the pre-equinox high latitude orbits revealed that the night side plasma sheet was tilted northward beyond a radial distance of ~15 Rs (1Rs=60,258 km). As equinox approached, Cassini observed a clear decrease in the tilt of the

Magnetospheric electrons

NASA Technical Reports Server (NTRS)

Coroniti, F. V.; Thorne, R. M.

1972-01-01

Coupling of source, transport, and sink processes produces a fairly accurate model for the macroscopic structure and dynamics of magnetospheric electrons. Auroral electrons are controlled by convective transport from a plasma sheet source coupled with a precipitation loss due to whistler and electrostatic plasma turbulence. Outer and inner zone electrons are governed by radial diffusion transport from convection and acceleration sources external to the plasmapause and by parasitic precipitation losses arising from cyclotron and Landau interactions with whistler and ion cyclotron turbulence.

Magnetosphere-ionosphere coupling: processes and rates

NASA Astrophysics Data System (ADS)

Lotko, W.

Magnetosphere-ionosphere coupling describes the interaction between the collisionless plasma of the magnetosphere and the ionized and neutral collisional gases of the ionosphere and thermosphere. This coupling introduces feedback and scale interactivity in the form of a time-variable mass flux, electron energy flux and Poynting flux flowing between the two regions. Although delineation of an MI coupling region is somewhat ambiguous, at mid and high latitudes it may be considered as the region of the topside ionosphere and low-altitude magnetosphere where electromagnetic energy is converted to plasma beams and heat via collisionless dissipation processes. Above this region the magnetically guided transmission of electromagnetic power from distant magnetospheric dynamos encounters only weak attenuation. The ionospheric region below it is dominated by ionization processes and collisional cross-field transport and current closure. This tutorial will use observations, models and theory to characterize three major issues in MI coupling: (1) the production of plasma beams and heat in the coupling region; (2) the acceleration of ions leading to massive outflows; and (3) the length and time scale dependence of electromagnetic energy deposition at low altitude. Our success in identifying many of the key processes is offset by a lack of quantitative understanding of the factors controlling the rates of energy deposition and of the production of particle energy and mass fluxes.

Inner Magnetospheric Electric Fields Derived from IMAGE EUV

NASA Technical Reports Server (NTRS)

Gallagher, D. L.; Adrian, M. L.

2007-01-01

The local and global patterns of plasmaspheric plasma transport reflect the influence of electric fields imposed by all sources in the inner magnetosphere. Image sequences of thermal plasma G:istribution obtained from the IMAGE Mission Extreme Ultraviolet Imager can be used to derive plasma motions and, using a magnetic field model, the corresponding electric fields. These motions and fields directly reflect the dynamic coupling of injected plasmasheet plasma and the ionosphere, in addition to solar wind and atmospheric drivers. What is being learned about the morphology of inner magnetospheric electric fields during storm and quite conditions from this new empirical tool will be presented and discussed.

Turbulent mass transfer caused by vortex induced reconnection in collisionless magnetospheric plasmas

DOE PAGES

Nakamura, T. K. M.; Hasegawa, H.; Daughton, William Scott; ...

2017-11-17

Magnetic reconnection is believed to be the main driver to transport solar wind into the Earth’s magnetosphere when the magnetopause features a large magnetic shear. However, even when the magnetic shear is too small for spontaneous reconnection, the Kelvin–Helmholtz instability driven by a super-Alfvénic velocity shear is expected to facilitate the transport. Although previous kinetic simulations have demonstrated that the non-linear vortex flows from the Kelvin–Helmholtz instability gives rise to vortex-induced reconnection and resulting plasma transport, the system sizes of these simulations were too small to allow the reconnection to evolve much beyond the electron scale as recently observed bymore » the Magnetospheric Multiscale (MMS) spacecraft. Here in this paper, based on a large-scale kinetic simulation and its comparison with MMS observations, we show for the first time that ion-scale jets from vortex-induced reconnection rapidly decay through self-generated turbulence, leading to a mass transfer rate nearly one order higher than previous expectations for the Kelvin–Helmholtz instability.« less

Turbulent mass transfer caused by vortex induced reconnection in collisionless magnetospheric plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, T. K. M.; Hasegawa, H.; Daughton, William Scott

Magnetic reconnection is believed to be the main driver to transport solar wind into the Earth’s magnetosphere when the magnetopause features a large magnetic shear. However, even when the magnetic shear is too small for spontaneous reconnection, the Kelvin–Helmholtz instability driven by a super-Alfvénic velocity shear is expected to facilitate the transport. Although previous kinetic simulations have demonstrated that the non-linear vortex flows from the Kelvin–Helmholtz instability gives rise to vortex-induced reconnection and resulting plasma transport, the system sizes of these simulations were too small to allow the reconnection to evolve much beyond the electron scale as recently observed bymore » the Magnetospheric Multiscale (MMS) spacecraft. Here in this paper, based on a large-scale kinetic simulation and its comparison with MMS observations, we show for the first time that ion-scale jets from vortex-induced reconnection rapidly decay through self-generated turbulence, leading to a mass transfer rate nearly one order higher than previous expectations for the Kelvin–Helmholtz instability.« less

Magnetosphere of Mercury : Observations and Insights from MESSENGER

NASA Astrophysics Data System (ADS)

Krimigis, Stamatios

The MESSENGER spacecraft executed three flyby encounters with Mercury in 2008 and 2009, was inserted into orbit about Mercury on 18 March 2011, and has returned a wealth of data on the magnetic field, plasma, and energetic particle environment of Mercury. These observations reveal a profoundly dynamic and active solar wind interaction. In addition to establishing the average structures of the bow shock, magnetopause, northern cusp, and tail plasma sheet, MESSENGER measurements document magnetopause boundary processes (reconnection and surface waves), global convection and dynamics (tail loading and unloading, magnetic flux transport, and Birkeland currents), surface precipitation of particles (protons and electrons), particle heating and acceleration, and wave generation processes (ions and electrons). Mercury’s solar wind interaction presents new challenges to our understanding of the physics of magnetospheres. The offset of the planetary moment relative to the geographic equator creates a larger hemispheric asymmetry relative to magnetospheric dimensions than at any other planet. The prevalence, magnitude, and repetition rates of flux transfer events at the magnetopause as well as plasmoids in the magnetotail indicate that, unlike at Earth, episodic convection may dominate over steady-state convection. The magnetopause reconnection rate is not only an order of magnitude greater than at Earth, but reconnection occurs over a much broader range of interplanetary magnetic field orientations than at Earth. Finally, the planetary body itself plays a significant role in Mercury’s magnetosphere. Birkeland currents close through the planet, induction at the planetary core-mantle boundary modifies the magnetospheric response to solar wind pressure excursions, the surface in darkness exhibits sporadic X-ray fluorescence consistent with precipitation of 10 to 100 keV electrons, magnetospheric plasmas precipitate directly onto the planetary surface and contribute to

Global Particle-in-Cell Simulations of Mercury's Magnetosphere

NASA Astrophysics Data System (ADS)

Schriver, D.; Travnicek, P. M.; Lapenta, G.; Amaya, J.; Gonzalez, D.; Richard, R. L.; Berchem, J.; Hellinger, P.

2017-12-01

Spacecraft observations of Mercury's magnetosphere have shown that kinetic ion and electron particle effects play a major role in the transport, acceleration, and loss of plasma within the magnetospheric system. Kinetic processes include reconnection, the breakdown of particle adiabaticity and wave-particle interactions. Because of the vast range in spatial scales involved in magnetospheric dynamics, from local electron Debye length scales ( meters) to solar wind/planetary magnetic scale lengths (tens to hundreds of planetary radii), fully self-consistent kinetic simulations of a global planetary magnetosphere remain challenging. Most global simulations of Earth's and other planet's magnetosphere are carried out using MHD, enhanced MHD (e.g., Hall MHD), hybrid, or a combination of MHD and particle in cell (PIC) simulations. Here, 3D kinetic self-consistent hybrid (ion particle, electron fluid) and full PIC (ion and electron particle) simulations of the solar wind interaction with Mercury's magnetosphere are carried out. Using the implicit PIC and hybrid simulations, Mercury's relatively small, but highly kinetic magnetosphere will be examined to determine how the self-consistent inclusion of electrons affects magnetic reconnection, particle transport and acceleration of plasma at Mercury. Also the spatial and energy profiles of precipitating magnetospheric ions and electrons onto Mercury's surface, which can strongly affect the regolith in terms of space weathering and particle outflow, will be examined with the PIC and hybrid codes. MESSENGER spacecraft observations are used both to initiate and validate the global kinetic simulations to achieve a deeper understanding of the role kinetic physics play in magnetospheric dynamics.

The magnetic geometry of Titan's induced magnetosphere

NASA Astrophysics Data System (ADS)

Bertucci, C.; Achilleos, N.; Dougherty, M. K.

2011-12-01

As a result of the virtual absence of an intrinsic field at Titan, an induced magnetosphere is formed from the direct interaction between its atmosphere and the plasma environment. Observations at unmagnetized objects such as comets, or planets like Venus and Mars, have shown that the orientation of the magnetic field within an induced magnetosphere is, on average, symmetric with respect to the plane generated by the upstream magnetic field and plasma velocity vectors. Analyses of Voyager and early Cassini magnetometer data around Titan confirm this feature. In this work, we study the efficiency of the background magnetic field-based 'draping coordinate system' (DRAP) introduced in Neubauer et al., [2006] to organize Cassini magnetometer (MAG) measurements within the induced magnetosphere of Titan for all the close flybys of the Prime Mission where MAG data is available. We find that, in general, DRAP coordinates are efficient in organizing the orientation of the draped magnetic field according to the pattern expected for an induced magnetosphere, suggesting that the same system could be used to spatially organize plasma measurements. Departures from this picture are likely related to non stationarity in the upstream flow, fossil fields and, induced currents within Titan's ionosphere and, probably, its interior. REFERENCES: Neubauer, F. M., et al. (2006). Titan's near magnetotail from magnetic field and electron plasma observations and modeling: Cassini flybys TA, TB, and T3. Journal of Geophysical Research, 111(A10), 1-15. doi: 10.1029/2006JA011676.

Auroral magnetosphere-ionosphere coupling: A brief topical review

NASA Technical Reports Server (NTRS)

Chiu, Y. T.; Schulz, M.; Cornwall, J. M.

1979-01-01

Auroral arcs result from the acceleration and precipitation of magnetospheric plasma in narrow regions characterized by strong electric fields both perpendicular and parallel to the earth's magnetic field. The various mechanisms that were proposed for the origin of such strong electric fields are often complementary Such mechanisms include: (1) electrostatic double layers; (2) double reverse shock; (3) anomalous resistivity; (4) magnetic mirroring of hot plasma; and (5) mapping of the magnetospheric-convection electric field through an auroral discontinuity.

Poker flat radar observations of the magnetosphere-ionosphere coupling electrodynamics of the earthward penetrating plasma sheet following convection enhancements

NASA Astrophysics Data System (ADS)

Lyons, L. R.; Zou, S.; Heinselman, C. J.; Nicolls, M. J.; Anderson, P. C.

2009-05-01

The plasma sheet moves earthward (equatorward in the ionosphere) after enhancements in convection, and the electrodynamics of this response is strongly influenced by Region 2 magnetosphere-ionosphere coupling. We have used Poker Flat Advanced Modular Incoherent Scatter Radar (PFISR) observations associated with two relatively abrupt southward turnings of the IMF to provide an initial evaluation of aspects of this response. The observations show that strong westward sub-auroral polarization streams (SAPS) flow regions moved equatorward as the plasma sheet electron precipitation (the diffuse aurora) penetrated equatorward following the IMF southward turnings. Consistent with our identification of these flows as SAPS, concurrent DMSP particle precipitation measurements show the equatorial boundary of ion precipitation equatorward of the electron precipitation boundary and that westward flows lie within the low-conductivity region between the two boundaries where the plasma sheet ion pressure gradient is expected to drive downward R2 currents. Evidence for these downward currents is seen in the DMSP magnetometer observations. Preliminary examination indicates that the SAPS response seen in the examples presented here may be common. However, detailed analysis will be required for many more events to reliably determine if this is the case. If so, it would imply that SAPS are frequently an important aspect of the inner magnetospheric electric field distribution, and that they are critical for understanding the response of the magnetosphere-ionosphere system to enhancements in convection, including understanding the earthward penetration of the plasma sheet. This earthward penetration is critical to geomagnetic disturbance phenomena such as the substorm growth phase and the formation of the stormtime ring current. Additionally, for one example, a prompt electric field response to the IMF southward turnings is seen within the inner plasma sheet.

Magnetic Dipole Inflation with Cascaded ARC and Applications to Mini-Magnetospheric Plasma Propulsion

NASA Technical Reports Server (NTRS)

Giersch, L.; Winglee, R.; Slough, J.; Ziemba, T.; Euripides, P.

2003-01-01

Mini-Magnetospheric Plasma Propulsion (M2P2) seeks to create a plasma-inflated magnetic bubble capable of intercepting significant thrust from the solar wind for the purposes of high speed, high efficiency spacecraft propulsion. Previous laboratory experiments into the M2P2 concept have primarily used helicon plasma sources to inflate the dipole magnetic field. The work presented here uses an alternative plasma source, the cascaded arc, in a geometry similar to that used in previous helicon experiments. Time resolved measurements of the equatorial plasma density have been conducted and the results are discussed. The equatorial plasma density transitions from an initially asymmetric configuration early in the shot to a quasisymmetric configuration during plasma production, and then returns to an asymmetric configuration when the source is shut off. The exact reasons for these changes in configuration are unknown, but convection of the loaded flux tube is suspected. The diffusion time was found to be an order of magnitude longer than the Bohm diffusion time for the period of time after the plasma source was shut off. The data collected indicate the plasma has an electron temperature of approximately 11 eV, an order of magnitude hotter than plasmas generated by cascaded arcs operating under different conditions. In addition, indirect evidence suggests that the plasma has a beta of order unity in the source region.

Effect of an MLT dependent electron loss rate on the inner magnetosphere electrodynamics and plasma sheet penetration to the ring current region

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Wang, C.; Wing, S.; Lyons, L. R.; Wolf, R. A.; Hsu, T.

2012-12-01

Transport of plasma sheet particles into the ring current region is strongly affected by the penetrating convection electric field, which is the result of the large-scale magnetosphere-ionosphere (M-I) electromagnetic coupling. One of the main factors controlling this coupling is the ionospheric conductance. As plasma sheet electrons drift earthward, they get scattered into the loss cone due to wave-particle interactions and precipitate to the ionosphere, producing auroral conductance. Realistic electron loss is thus important for modeling the (M-I) coupling and penetration of plasma sheet into the inner magnetosphere. To evaluate the significance of electron loss rate, we used the Rice Convection Model (RCM) coupled with a force-balanced magnetic field to simulate plasma sheet transport under different electron loss rates and under self-consistent electric and magnetic field. The plasma sheet ion and electron sources for the simulations are based on the Geotail observations. Two major rates are used: different portions of i) strong pitch-angle diffusion everywhere electron loss rate (strong rate) and ii) a more realistic loss rate with its MLT dependence determined by wave activity (MLT rate). We found that the dawn-dusk asymmetry in the precipitating electron energy flux under the MLT rate, with much higher energy flux at dawn than at dusk, agrees better with statistical DMSP observations. Electrons trapped inside L ~ 8 RE can remain there for many hours under the MLT rate, while those under the strong rate get lost within minutes. Compared with the strong rate, the remaining electrons under the MLT rate cause higher conductance at lower latitudes, allowing for less efficient electric field shielding to convection enhancement, thus further earthward penetration of the plasma sheet into the inner magnetosphere. Therefore, our simulation results indicate that the electron loss rate can significantly affect the electrodynamics of the ring current region. Development

A mechanism for magnetospheric substorms

NASA Technical Reports Server (NTRS)

Erickson, G. M.; Heinemann, M.

1994-01-01

Energy-principle analysis performed on two-dimensional, self-consistent solutions for magnetospheric convection indicates that the magnetosphere is unstable to isobaric (yet still frozen-in) fluctuations of plasma-sheet flux tubes. Normally, pdV work associated with compression maintains stability of the inward/outward oscillating normal mode. However, if Earth's ionosphere can provide sufficient mass flux, isobaric expansion of flux tubes can occur. The growth of a field-aligned potential drop in the near-Earth, midnight portion of the plasma sheet, associated with upward field-aligned currents responsible for the Harang discontinuity, redistributes plasma along field lines in a manner that destabilizes the normal mode. The growth of this unstable mode results in an out-of-equilibrium situation near the inner edge. When this occurs over a downtail extent comparable to the half-thickness of the plasma sheet, collapse ensues and forces thinning of the plasma sheet whereby conditions favorable to reconnection occur. This scenario for substorm onset is consistent with observed upward fluxes of ions, parallel potential drops, and observations of substorm onset. These observations include near Earth onset, pseudobreakups, the substorm current wedge, and local variations of plasma-sheet thickness.

Composition of hot ions /0.1-16 keV/e/ as observed by the GEOS and ISEE mass spectrometers and inferences for the origin and circulation of magnetospheric plasmas

NASA Technical Reports Server (NTRS)

Balsiger, H.

1981-01-01

The composition of hot magnetospheric plasma through different regions of the magnetosphere is described on the basis of mass spectrometer measurements by the GEOS 1, GEOS 2, and ISEE-1 spacecraft. Coordinated composition measurements on the different spacecraft also provide information on the spatial and temporal characteristics of the plasma during storms. Data on ion origins are also provided.

In-situ Plasma Analysis of Ion Kinetics in the Solar Wind and Hermean Magnetosphere

NASA Astrophysics Data System (ADS)

Tracy, Patrick J.

The heating of the solar wind and its interaction with the unique planetary magnetosphere of Mercury is the primary focus of this work. The first aspect of this study focused on the heavy ion population of the solar wind (A > 4 amu), and how well the signature of the heating process responsible for creating the solar wind is preserved in this heavy ion population. We found that this signature in the heavy ion population is primarily erased (thermalized) via Coulomb collisional interactions with solar wind protons. The heavy ions observed in collisionally young solar wind reveal a clear, stable dependence on mass, along with non-thermal heating that is not in agreement with current predictions based on turbulent transport and kinetic dissipation. Due to its weak magnetic dipole, the solar wind can impinge on the surface of Mercury, one of the processes contributing to the desorption of neutrals and, through ionization, ions that make up the planet's exosphere. Differentiating between surface mechanisms and analyzing magnetospheric plasma dynamics requires the quantification of a variety of ion species. A detailed forward model and a robust statistical method were created to identify new ion signatures in the measurement space of the FIPS instrument, formerly orbiting Mercury onboard the MESSENGER spacecraft. The recovery of new heavy ions species, including Al, Ne, Si, and Mg, along with tentative recoveries of S, Ar, K, and C, enable in depth studies of the plasma dynamics in the Hermean magnetosphere. The interaction of the solar wind with the bow shock of the Hermean magnetosphere leads to the creation of a foreshock region. New tools and methods were created to enable the analysis of the diffuse and Field Aligned Beam (FAB) populations in unique parameter regime of the Hermean foreshock. One result suggests that the energization process for the observed FABs can be explained by Shock Drift Acceleration, and not limited by the small spatial size of Mercury's bow

Possibility of magnetospheric VLF response to atmospheric infrasonic waves

NASA Astrophysics Data System (ADS)

Bespalov, P. A.; Savina, O. N.

2012-06-01

In this paper, we consider a model of the influence of atmospheric infrasonic waves on VLF magnetospheric whistler wave excitation. This excitation occurs as a result of a succession of processes: a modulation of the plasma density by acoustic-gravity waves in the ionosphere, a reflection of the whistlers by ionosphere modulation, and a modification of whistler wave generation in the magnetospheric resonator. A variation of the magnetospheric resonator Q-factor has an influence on the operation of the plasma magnetospheric maser, where the active substances are radiation belt particles, and the working modes are electromagnetic whistler waves. The magnetospheric maser is an oscillating system which can be responsible for the excitation of self-oscillations. These self-oscillations are frequently characterized by alternating stages of accumulation and precipitation of energetic particles into the ionosphere during a pulse of whistler emissions. Numerical and analytical investigations of the response of self-oscillations to harmonic oscillations of the whistler reflection coefficient shows that even a small modulation rate can significantly change magnetospheric VLF emissions. Our results can explain the causes of the modulation of energetic electron fluxes and whistler wave intensity with a time scale from 10 to 150 s in the day-side magnetosphere. Such quasi-periodic VLF emissions are often observed in the sub-auroral and auroral magnetosphere and have a noticeable effect on the formation of space weather phenomena.

Jupiter's magnetosphere and radiation belts

NASA Technical Reports Server (NTRS)

Kennel, C. F.; Coroniti, F. V.

1979-01-01

Radioastronomy and Pioneer data reveal the Jovian magnetosphere as a rotating magnetized source of relativistic particles and radio emission, comparable to astrophysical cosmic ray and radio sources, such as pulsars. According to Pioneer data, the magnetic field in the outer magnetosphere is radially extended into a highly time variable disk-shaped configuration which differs fundamentally from the earth's magnetosphere. The outer disk region, and the energetic particles confined in it, are modulated by Jupiter's 10 hr rotation period. The entire outer magnetosphere appears to change drastically on time scales of a few days to a week. In addition to its known modulation of the Jovian decametric radio bursts, Io was found to absorb some radiation belt particles and to accelerate others, and most importantly, to be a source of neutral atoms, and by inference, a heavy ion plasma which may significantly affect the hydrodynamic flow in the magnetosphere. Another important Pioneer finding is that the Jovian outer magnetosphere generates, or permits to escape, fluxes of relativistic electrons of such intensities that Jupiter may be regarded as the dominant source of 1 to 30 MeV cosmic ray electrons in the heliosphere.

Two Dual Ion Spectrometer Flight Units of the Fast Plasma Instrument Suite (FPI) for the Magnetospheric Multiscale Mission (MMS)

NASA Technical Reports Server (NTRS)

Adams, Mitzi

2014-01-01

Two Dual Ion Spectrometer flight units of the Fast Plasma Instrument Suite (FPI) for the Magnetospheric Multiscale Mission (MMS) have returned to MSFC for flight testing. Anticipated to begin on June 30, tests will ensue in the Low Energy Electron and Ion Facility of the Heliophysics and Planetary Science Office (ZP13), managed by Dr. Victoria Coffey of the Natural Environments Branch of the Engineering Directorate (EV44). The MMS mission consists of four identical spacecraft, whose purpose is to study magnetic reconnection in the boundary regions of Earth's magnetosphere.

Nonlinear electric field structures in the inner magnetosphere

DOE PAGES

Malaspina, D. M.; Andersson, L.; Ergun, R. E.; ...

2014-08-28

Recent observations by the Van Allen Probes spacecraft have demonstrated that a variety of electric field structures and nonlinear waves frequently occur in the inner terrestrial magnetosphere, including phase space holes, kinetic field-line resonances, nonlinear whistler-mode waves, and several types of double layer. However, it is nuclear whether such structures and waves have a significant impact on the dynamics of the inner magnetosphere, including the radiation belts and ring current. To make progress toward quantifying their importance, this study statistically evaluates the correlation of such structures and waves with plasma boundaries. A strong correlation is found. These statistical results, combinedmore » with observations of electric field activity at propagating plasma boundaries, are consistent with the identification of these boundaries as the source of free energy responsible for generating the electric field structures and nonlinear waves of interest. Therefore, the ability of these structures and waves to influence plasma in the inner magnetosphere is governed by the spatial extent and dynamics of macroscopic plasma boundaries in that region.« less

Ionosphere-Magnetosphere Energy Interplay in the Regions of Diffuse Aurora

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Glocer, A.; Sibeck, D. G.; Tripathi, A. K.; Detweiler, L.G.; Avanov, L. A.; Singhal, R. P.

2016-01-01

Both electron cyclotron harmonic (ECH) waves and whistler mode chorus waves resonate with electrons of the Earths plasma sheet in the energy range from tens of eV to several keV and produce the electron diffuse aurora at ionospheric altitudes. Interaction of these superthermal electrons with the neutral atmosphere leads to the production of secondary electrons (E500600 eV) and, as a result, leads to the activation of lower energy superthermal electron spectra that can escape back to the magnetosphere and contribute to the thermal electron energy deposition processes in the magnetospheric plasma. The ECH and whistler mode chorus waves, however, can also interact with the secondary electrons that are coming from both of the magnetically conjugated ionospheres after they have been produced by initially precipitated high-energy electrons that came from the plasma sheet. After their degradation and subsequent reflection in magnetically conjugate atmospheric regions, both the secondary electrons and the precipitating electrons with high (E600 eV) initial energies will travel back through the loss cone, become trapped in the magnetosphere, and redistribute the energy content of the magnetosphere-ionosphere system. Thus, scattering of the secondary electrons by ECH and whistler mode chorus waves leads to an increase of the fraction of superthermal electron energy deposited into the core magnetospheric plasma.

Observation of magnetic fluctuations and rapid density decay of magnetospheric plasma in Ring Trap 1

NASA Astrophysics Data System (ADS)

Saitoh, H.; Yoshida, Z.; Morikawa, J.; Yano, Y.; Mikami, H.; Kasaoka, N.; Sakamoto, W.

2012-06-01

The Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet, has created high-β (local β ˜ 70%) plasma by using electron cyclotron resonance heating (ECH). When a large population of energetic electrons is generated at low neutral gas pressure operation, high frequency magnetic fluctuations are observed. When the fluctuations are strongly excited, rapid loss of plasma was simultaneously observed especially in a quiet decay phase after the ECH microwave power is turned off. Although the plasma is confined in a strongly inhomogeneous dipole field configuration, the frequency spectra of the fluctuations have sharp frequency peaks, implying spatially localized sources of the fluctuations. The fluctuations are stabilized by decreasing the hot electron component below approximately 40%, realizing stable high-β confinement.

Linking Plasma Conditions in the Magnetosphere with Ionospheric Signatures

NASA Technical Reports Server (NTRS)

Rastaetter, Lutz; Kozyra, Janet; Kuznetsova, Maria M.; Berrios, David H.

2012-01-01

Modeling of the full magnetosphere, ring current and ionosphere system has become an indispensable tool in analyzing the series of events that occur during geomagnetic storms. The CCMC has a full model suite available for the magnetosphere, together with visualization tools that allow a user to perform a large variety of analyses. The January, 21, 2005 storm was a moderate-size storm that has been found to feature a large penetration electric field and unusually large polar caps (low-latitude precipitation patterns) that are otherwise found in super storms. Based on simulations runs at CCMC we can outline the likely causes of this behavior. Using visualization tools available to the online user we compare results from different magnetosphere models and present connections found between features in the magnetosphere and the ionosphere that are connected magnetically. The range of magnetic mappings found with different models can be compared with statistical models (Tsyganenko) and the model's fidelity can be verified with observations from low earth orbiting satellites such as DMSP and TIMED.

Effects of Energetic Ion Outflow on Magnetospheric Dynamics

NASA Astrophysics Data System (ADS)

Kistler, L. M.; Mouikis, C.; Lund, E. J.; Menz, A.; Nowrouzi, N.

2016-12-01

There are two dominant regions of energetic ion outflow: the nightside auroral region and the dayside cusp. Processes in these regions can accelerate ions up to keV energies. Outflow from the nightside has direct access to the plasma sheet, while outflow from the cusp is convected over the polar cap and into the lobes. The cusp population can enter the plasma sheet from the lobe, with higher energy ions entering further down the tail than lower energy ions. During storm times, the O+ enhanced plasma sheet population is convected into the inner magnetosphere. The plasma that does not get trapped in the inner magnetosphere convects to the magnetopause where reconnection is taking place. An enhanced O+ population can change the plasma mass density, which may have the effect of decreasing the reconnection rate. In addition O+ has a larger gyroradius than H+ at the same velocity or energy. Because of this, there are larger regions where the O+ is demagnetized, which can lead to larger acceleration because the O+ can move farther in the direction of the electric field. In this talk we will review results from Cluster, Van Allen Probes, and MMS, on how outflow from the two locations affects magnetospheric dynamics. We will discuss whether enhanced O+ from either population has an effect on the reconnection rate in the tail or at the magnetopause. We will discuss how the two populations impact the inner magnetosphere during storm times. And finally, we will discuss whether either population plays a role in triggering substorms, particularly during sawtooth events.

Europa's Interaction with Jupiter's Magnetosphere: Galileo Plasma Observations Revisited.

NASA Astrophysics Data System (ADS)

Heuer, S. V.; Rymer, A. M.; Westlake, J. H.; Paterson, W. R.; Collinson, G.

2017-12-01

The Galileo spacecraft was active at Jupiter from December 1995 to September 2003, carrying the Galileo Plasma Science Instrument (PLS), an electrostatic analyzer with three spherical-segment plates which directed energy selected particles into one of seven electron sensors or seven ion channels with field-of-views which combined to cover 80% of the 4pi-sr unit sphere (Frank et al., 1992). While Galileo accomplished most of its primary scientific objectives, the mission did not reach its full potential due to a failed high-gain antenna deployment which severely limited the available bandwidth for data transmission. Consequently, the PLS was limited by bandwidth availability, and only collected data with high temporal and energy resolution for short periods of time (e.g. review by Bagenal et al., 2016). The electron sensors were also negatively affected by the gaseous environment around Jupiter, which is suspected to have deposited a layer of contaminants on the detectors, raising the threshold energy required to pass through the aperture and effectively preventing the measurement of electrons below 1keV (Frank et al., 2002). As a result, data from the PLS is challenging to process and interpret. Ion plasma moments have been computed (and published on the PDS) in the magnetosphere, but moon flybys were excluded (Bagenal et al., 2016). In anticipation of future in-situ exploration of the Europa plasma environment, we present analysis of full-resolution plasma data acquired by the PLS during the nine Europa flybys and compare our results with existing data in order to further inform designs currently being worked for the Europa Clipper and JUICE missions.

Magnetospheric equilibrium configurations and slow adiabatic convection

NASA Technical Reports Server (NTRS)

Voigt, Gerd-Hannes

1986-01-01

This review paper demonstrates how the magnetohydrostatic equilibrium (MHE) theory can be used to describe the large-scale magnetic field configuration of the magnetosphere and its time evolution under the influence of magnetospheric convection. The equilibrium problem is reviewed, and levels of B-field modelling are examined for vacuum models, quasi-static equilibrium models, and MHD models. Results from two-dimensional MHE theory as they apply to the Grad-Shafranov equation, linear equilibria, the asymptotic theory, magnetospheric convection and the substorm mechanism, and plasma anisotropies are addressed. Results from three-dimensional MHE theory are considered as they apply to an intermediate analytical magnetospheric model, magnetotail configurations, and magnetopause boundary conditions and the influence of the IMF.

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.

Laboratory Experiments Enabling Electron Beam use in Tenuous Space Plasmas

NASA Astrophysics Data System (ADS)

Miars, G.; Leon, O.; Gilchrist, B. E.; Delzanno, G. L.; Castello, F. L.; Borovsky, J.

2017-12-01

A mission concept is under development which involves firing a spacecraft-mounted electron beam from Earth's magnetosphere to connect distant magnetic field lines in real time. To prevent excessive spacecraft charging and consequent beam return, the spacecraft must be neutralized in the tenuous plasma environment of the magnetosphere. Particle-In-Cell (PIC) simulations suggest neutralization can be accomplished by emitting a neutral plasma with the electron beam. Interpretation of these simulations also led to an ion emission model in which ion current is emitted from a quasi-neutral plasma as defined by the space charge limit [1,2]. Experiments were performed at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL) to help validate the ion emission model. A hollow cathode plasma contactor was used as a representative spacecraft and charged with respect to the chamber walls to examine the effect of spacecraft charging on ion emission. Retarding Potential Analyzer (RPA) measurements were performed to understand ion flow velocity as this parameter relates directly to the expected space charge limit. Planar probe measurements were also made to identify where ion emission primarily occurred and to determine emission current density levels. Evidence of collisions within the plasma (particularly charge exchange collisions) and a simple model predicting emitted ion velocities are presented. While a detailed validation of the ion emission model and of the simulation tools used in [1,2] is ongoing, these measurements add to the physical understanding of ion emission as it may occur in the magnetosphere. 1. G.L. Delzanno, J.E. Borovsky, M.F. Thomsen, J.D. Moulton, and E.A. MacDonald, J. Geophys. Res. Space Physics 120, 3647, 2015. 2. G.L. Delzanno, J.E. Borovsky, M.F. Thomsen, and J.D. Moulton, J. Geophys. Res. Space Physics 120, 3588, 2015. ________________________________ * This work is supported by Los Alamos National Laboratory.

Simulation of Mini-Magnetospheric Plasma Propulsion (M2P2) Interacting with an External Plasma Wind

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Euripides, P.; Ziemba, T.; Slough, J.; Giersch, L.

2003-01-01

Substantial progress has been made over the last year in the development of the laboratory Mini-Magnetospheric Plasma Propulsion (M2P2) prototype. The laboratory testing has shown that that the plasma can be produced at high neutral gas efficiency, at high temperatures (a few tens of eV) with excellent confinement up to the point where chamber wall interactions dominate the physics. This paper investigates the performance of the prototype as it is opposed by an external plasma acting as a surrogate for the solar wind. The experiments were performed in 5ft diameter by 6ft long vacuum chamber at the University of Washington. The solar wind source comprised of a 33 kWe arc jet attached to a 200 kWe inductively generated plasma source. The dual plasma sources allow the interaction to be studied for different power levels, shot duration and production method. It is shown that plasma from the solar wind source (SWS) is able to penetrate the field of the M2P2 magnetic when no plasma is present. With operation of the M2P2 plasma source at only 1.5 kWe, the penetration of the SWS even at the highest power of operation at 200 kWe is stopped. This deflection is shown to be greatly enhanced over that produced by the magnet alone. In addition it is shown that with the presence of the SWS, M2P2 is able to produce enhanced magnetized plasma production out to at least 10 magnet radii where the field strength is only marginally greater than the terrestrial field. The results are consistent with the initial predictions that kWe M2P2 systems would be able to deflect several hundred kWe plasma winds to produce enhanced propulsion for a spacecraft.

Generation of region 1 current by magnetospheric pressure gradients

NASA Technical Reports Server (NTRS)

Yang, Y. S.; Spiro, R. W.; Wolf, R. A.

1994-01-01

The Rice Convection Model (RCM) is used to illustrate theoretical possibilities for generating region 1 Birkeland currents by pressure gradients on closed field lines in the Earth's magnetosphere. Inertial effects and viscous forces are neglected. The RCM is applied to idealized cases, to emphasize the basic physical ideas rather than realistic representation of the actual magnetosphere. Ionospheric conductance is taken to be uniform, and the simplest possible representations of the magnetospheric plasma are used. Three basic cases are considered: (1) the case of pure northward Interplanetary Magnetic Field (IMF), with cusp merging assumed to create new closed field lines near the nose of the magnetosphere, following the suggestion by Song and Russell (1992); (2) the case where Dungey-type reconnection occurs at the nose, but magnetosheath plasma somehow enters closed field lines on the dawnside and duskside of the merging region, causing a pressure-driven low-latitude boundary layer; and (3) the case where Dungey-type reconnection occurs at the nose, but region 1 currents flow on sunward drifting plasma sheet field lines. In case 1, currents of region 1 sense are generated by pressure gradients, but those currents do not supply the power for ionospheric convection. Results for case 2 suggest that pressure gradients at the inner edge of the low-latitude boundary layer might generate a large fraction of the region 1 Birkeland currents that drive magnetospheric convection. Results for case 3 indicate that pressure gradients in the plasma sheet could provide part of the region 1 current.

Modeling Enceladus and its torus in Saturn's magnetosphere (Invited)

NASA Astrophysics Data System (ADS)

Jia, Y.; Russell, C. T.; Khurana, K. K.; Gombosi, T. I.

2010-12-01

The dynamics of the saturnian magnetosphere is controlled by the planetary spin at a rate of about 10.5 hours. The second icy moon of Saturn, Enceladus, orbits at 4 planetary radii deep in the inner magnetosphere. Enceladus creates neutrals at a rate of hundreds of kilograms per second. These neutrals are ionized and picked up by the ambient plasma and spun up to the corotational velocity to form a plasma disk. Consequently, the gas and plasma density peak close to the Enceladus orbit. In the gas torus, the majority of the gas particles travel at their keplerian speed of 14 km/s, while the bulk of the plasma rotates at 30-40 km/s as a response to the rigid spinning of the saturnian magnetic field. The corotating plasma torus feels a centrifugal force that is balanced by the magnetic tension force. To balance the centripetal force of this plasma disk, Saturn’s magnetic field is stretched in both radial and azimuthal directions. At Enceladus the massive pickup of new ions from its plume slows down the corotating flow and breaks this force balance to cause plasma flows in the radial direction of Saturn. Such radial flows in the inner magnetosphere of Saturn are supported by Cassini observations using various particle and field instruments. In this study we summarize the lessons learned from recent Cassini observations and our numerical simulation effort of the local interactions at Enceladus, and model the inner magnetosphere of Saturn to reproduce the force balance processes. The neutral torus is treated as a background in this axis-symmetric model.

Plasma physics and environmental perturbation laboratory. [magnetospheric experiments from space shuttle

NASA Technical Reports Server (NTRS)

Vogl, J. L.

1973-01-01

Current work aimed at identifying the active magnetospheric experiments that can be performed from the Space Shuttle, and designing a laboratory to carry out these experiments is described. The laboratory, known as the PPEPL (Plasma Physics and Environmental Perturbation Laboratory) consists of 35-ft pallet of instruments connected to a 25-ft pressurized control module. The systems deployed from the pallet are two 50-m booms, two subsatellites, a high-power transmitter, a multipurpose accelerator, a set of deployable canisters, and a gimbaled instrument platform. Missions are planned to last seven days, during which two scientists will carry out experiments from within the pressurized module. The type of experiments to be performed are outlined.

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

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.

Moon-Magnetosphere Interactions at Saturn: Recent Highlights from Cassini Observations and Modelling

NASA Astrophysics Data System (ADS)

Simon, S.; Kriegel, H.; Saur, J.; Neubauer, F. M.; Wennmacher, A.; Motschmann, U.; Dougherty, M. K.

2012-09-01

Since the arrival of the Cassini spacecraft at Saturn in July 2004, newly collected plasma and magnetic field data have greatly expanded our knowledge on the giant planet's magnetosphere and its multifaceted family of moons. More than 160 orbits around the planet have already been accomplished by Cassini, encompassing 85 close flybys of Saturn's largest satellite Titan as well as 20 encounters of Enceladus. This small icy moon had been identified as the major source of magnetospheric plasma and neutral particles during the first year of Cassini's tour in the Saturnian system. In addition, the spacecraft has paid visits to several of the other icy satellites in the inner and middle magnetosphere: Rhea (3 flybys), Dione (3 flybys) and Tethys (1 flyby). The inner icy satellites and Titan are located within Saturn's magnetosphere for average solar wind conditions, revolving around the giant planet on prograde orbits in its equatorial plane. Since their orbital velocities are clearly exceeded by the speed of the at least partially corotating magnetospheric plasma, the moons are continuously "overtaken" by the magnetospheric flow. Thus, their trailing hemispheres are permanently exposed to a bombardment with thermal magnetospheric plasma. The characteristics of the resulting plasma interaction process depend on the properties of the moon itself as well as on the parameters (density, velocity, temperature, magnetic field strength) of the incident magnetospheric flow and the energetic particle population. In this presentation, we shall review some recent advances in our understanding of the interaction between Saturn's moons and their plasma environment: Enceladus: Electron absorption by submicron dust grains within the plume gives rise to a negative sign of the Hall conductance in Enceladus' plume. The resulting twist of the magnetic field, referred to as the Anti-Hall effect, has been observed during all targeted Enceladus flybys accomplished to date. We present an

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.

Modelling the Auroral Magnetosphere-Ionosphere Coupling System at Jupiter

NASA Astrophysics Data System (ADS)

Bunce, E. J.; Cowley, S.; Provan, G.

2016-12-01

The magnetosphere-ionosphere coupling system at Jupiter is a topic of central significance in understanding the fundamental properties of its large-scale plasma environment. Theoretical discussion of this topic typically considers the properties of the field-aligned current systems that form part of a large-scale magnetosphere-ionosphere coupling current system associated with momentum exchange between the ionosphere and the magnetosphere, communicated via the magnetic field. The current system associated with the main oval is believed to be related to centrifugally-driven outward radial transport of iogenic plasma that leads to sub-corotation in the middle magnetosphere. In addition to the magnetosphere-ionosphere coupling current system, upward-directed field-aligned currents may flow at the open-closed field line boundary due to the shear between outer closed field lines and open field lines, which may relate to emission poleward of the main oval. An axi-symmetric model of the plasma flow in the jovian system, the related coupling currents, and the consequent auroral precipitation based on these combined ideas was initially devised to represent typical steady-state conditions for the system and later extended to consider auroral effects resulting from sudden compressions of the magnetosphere. More recently, the model has been extended along model magnetic field lines into the magnetosphere in order to relate them to in situ observations from the NASA Juno spacecraft at Jupiter. The field-aligned coupling currents associated with the modelled current systems produce a readily-observable azimuthal field signature that bends the field lines out of magnetic meridians. Here we show the computed azimuthal fields produced by our model auroral current system throughout the region between the ionosphere and the magnetic equator, and illustrate the results by evaluation of various model parameters (e.g. field-aligned current density, accelerating voltages, accelerated

Observations & modeling of solar-wind/magnetospheric interactions

NASA Astrophysics Data System (ADS)

Hoilijoki, Sanni; Von Alfthan, Sebastian; Pfau-Kempf, Yann; Palmroth, Minna; Ganse, Urs

2016-07-01

The majority of the global magnetospheric dynamics is driven by magnetic reconnection, indicating the need to understand and predict reconnection processes and their global consequences. So far, global magnetospheric dynamics has been simulated using mainly magnetohydrodynamic (MHD) models, which are approximate but fast enough to be executed in real time or near-real time. Due to their fast computation times, MHD models are currently the only possible frameworks for space weather predictions. However, in MHD models reconnection is not treated kinetically. In this presentation we will compare the results from global kinetic (hybrid-Vlasov) and global MHD simulations. Both simulations are compared with in-situ measurements. We will show that the kinetic processes at the bow shock, in the magnetosheath and at the magnetopause affect global dynamics even during steady solar wind conditions. Foreshock processes cause an asymmetry in the magnetosheath plasma, indicating that the plasma entering the magnetosphere is not symmetrical on different sides of the magnetosphere. Behind the bow shock in the magnetosheath kinetic wave modes appear. Some of these waves propagate to the magnetopause and have an effect on the magnetopause reconnection. Therefore we find that kinetic phenomena have a significant role in the interaction between the solar wind and the magnetosphere. While kinetic models cannot be executed in real time currently, they could be used to extract heuristics to be added in the faster MHD models.

The Plasmaspheric Role in Coupled Inner Magnetospheric Dynamics

NASA Astrophysics Data System (ADS)

Goldstein, J.

2006-05-01

The plasmasphere is a near-Earth cold, dense, corotating plasma region that plays both passive and active roles in inner magnetospheric coupling. The plasmasphere plays a passive role with respect to electrodynamic coupling associated with enhanced magnetospheric convection; i.e., zero-order plasmaspheric dynamics result from convection. Following extended periods of quiet geomagnetic conditions, the equatorial extent of the plasmasphere can be several Earth radii (RE), with an internal density distribution that contains a great deal of fine-scale (under 0.1 RE) and meso-scale (0.1 to 1 RE) density structure. Enhanced geomagnetic activity causes erosion of the plasmasphere, in which the outer plasma-filled flux tubes are caught up in the convection field and carried sunward, forming plumes of dense plasmaspheric material on the dayside. The electrodynamic coupling between the ring current and ionosphere (leading to shielding and sub-auroral polarization stream, or SAPS) can either reduce or intensify the global convection field that arises from solar-wind-magnetosphere coupling, and the plasmasphere is subject to the variations of this convection. There is also good evidence that ionosphere-thermosphere coupling plays an important role in determination of the convection field during quiet conditions. The plasmasphere plays an active role in determining the global distribution of warmer inner magnetospheric plasmas (ring current and radiation belts), by providing plasma conditions that can favor or discourage the growth of waves such as whistler, chorus, and electromagnetic ion-cyclotron (EMIC) waves, all of which are believed to be crucial in the various acceleration and loss processes that affect warmer particles. Thus, knowledge of the global plasmasphere configuration and composition is critical for understanding and predicting the behavior of the inner magnetosphere.

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.

Buoyancy Waves in Earth's Magnetosphere: Calculations for a 2-D Wedge Magnetosphere

NASA Astrophysics Data System (ADS)

Wolf, R. A.; Toffoletto, F. R.; Schutza, A. M.; Yang, J.

2018-05-01

To improve theoretical understanding of the braking oscillations observed in Earth's inner plasma sheet, we have derived a theoretical model that describes k∥ = 0 magnetohydrodynamic waves in an idealized magnetospheric configuration that consists of a 2-D wedge with circular-arc field lines. The low-frequency, short-perpendicular-wavelength mode obeys a differential equation that is often used to describe buoyancy oscillations in a neutral atmosphere, so we call those waves "buoyancy waves," though the magnetospheric buoyancy force results from magnetic tension rather than gravity. Propagation of the wave is governed mainly by a position-dependent frequency ωb, the "buoyancy frequency," which is a fundamental property of the magnetosphere. The waves propagate if ωb > ω but otherwise evanesce. In the wedge magnetosphere, ωb turns out to be exactly the fundamental oscillation frequency for poloidal oscillations of a thin magnetic filament, and we assume that the same is true for the real magnetosphere. Observable properties of buoyancy oscillations are discussed, but propagation characteristics vary considerably with the state of the magnetosphere. For a given event, the buoyancy frequency and propagation characteristics can be determined from pressure and density profiles and a magnetic field model, and these characteristics have been worked out for one typical configuration. A localized disturbance that initially resembles a dipolarizing flux bundle spreads east-west and also penetrates into the plasmasphere to some extent. The calculated amplitude near the center of the original wave packet decays in a few oscillation periods, even though our calculation includes no dissipation.

Highlights of theoretical progress related to the International Magnetospheric Study

NASA Technical Reports Server (NTRS)

Hill, T. W.

1982-01-01

U.S. theoretical research efforts have addressed three areas within the International Magnetospheric Study. The first, solar wind/magnetosphere interaction, is presently concerned with the suggestion that magnetic merging may predominantly occur near the polar cusps rather than near the subsolar point. Mechanisms have been proposed for noncollisional diffusion of solar wind plasma across the closed magnetopause entailed by such a phenomenon. The second area considers the importance to magnetotail dynamics of a continuous source of solar wind plasma, and of sporadic plasma loss associated with an unsteady convection cycle. In the third area, the electrodynamic magnetosphere/ionosphere interaction, an advanced state has been reached in the understanding of the relevant physics, with respect both to coupling in the subauroral region and the large scale structure of auroral zone electric fields parallel, and perpendicular to, the magnetic field.

Outstanding Issues and Future Directions of Inner Magnetospheric Research (Invited)

NASA Astrophysics Data System (ADS)

Brandt, P. C.

2009-12-01

Several research areas of the inner magnetosphere and ionosphere (MI) system have reached a state, where the coupling mechanisms can no longer be treated as boundary conditions or ad-hoc assumptions in our physical models. It is nothing new that our community has become increasingly aware of the necessity to use global measurements from multiple observation platforms and missions, in order to understand both the system as a whole as well as its individual subsystems. In this presentation we briefly review the current status and outstanding issues of inner MI research. We attempt to establish a working definition of the term "Systems Approach", then present observational tools and techniques that enable such an approach. Physical modeling plays a central role not only in understanding the mechanisms at work, but also in determining the key quantities to be measured. We conclude by discussing questions relevant to future directions. Are there new techniques that need more attention? Should multi-platform observations be included as a default component already at the mission-level in the future? Is solar minimum uninteresting from an MI perspective? Should we actively compare to magnetospheres of other planets? Examples of outstanding issues in inner MI research include the circulation of ionospheric plasma from low to high latitudes and its escape to the magnetosphere, where it is energized by magnetospheric processes and becomes a part of the plasma pressure that in turn affects the ionospheric and magnetospheric electric field. The electric field, in turn, plays a controlling role in the transport of both magnetospheric and ionospheric plasma, which is intimately linked with ionospheric conductance. The conductance, in turn, is controlled by thermospheric chemistry coupled with plasma flow and heating and magnetospheric precipitation and Joule heating. Several techniques have emerged as important tools: auroral imaging, inversions of ENA images to retrieve the

A Voyager Perspective of Ice Giant Magnetospheres: What Next?

NASA Astrophysics Data System (ADS)

Kurth, W. S.; Hospodarsky, G. B.

2017-12-01

Voyager 2 provided our only in situ observations of the magnetospheres of Uranus (in 1986) and Neptune (in 1989). And, given that Earth-based radio observations have not acquired auroral radio emissions from these planets, the only remote observations of magnetospheric phenomena at these planets are of their auroras. This paper provides an overview of the Voyager observations of these ice giant magnetospheres as a stepping off point for the possibility of missions launching to one or both of these planets in the next decade or so. Both of these magnetospheres are rich in phenomena found in other planetary magnetospheres including plasmas and energetic particles, currents, radio and plasma waves, auroras, and dust. Perhaps the thing that sets these magnetospheres off from those of Earth, Jupiter, and Saturn are the very large tilt of their magnetic moments with respect to their rotation axes. With such tilts, the magnetospheres can be reconfigured every rotation as the magnetic configuration with respect to the impinging solar wind continually changes. The Voyager flybys provided only hints of how these reconfigurations work. Certainly even another flyby mission would effectively double the range of states observed for them. But, a mission including an orbiter would provide an amazing opportunity to observe these dramatic changes through not only a cycle, but repeatedly. A suitably instrumented spacecraft could provide understanding for how these planets work as systems including satellites, rings, and magnetic fields tying them to the ice giant.

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.

Ion energization in Ganymede's magnetosphere: Using multifluid simulations to interpret ion energy spectrograms

NASA Astrophysics Data System (ADS)

Paty, C.; Paterson, W.; Winglee, R.

2008-06-01

We investigate the ion population and energy distribution within Ganymede's magnetosphere by examining Ganymede's ionospheric outflow as a source of heavy (O+) and light (H+) ions and the Jovian magnetospheric plasma as an external source of heavy ions. We develop a method for examining the energy distributions of each ion species in a three-dimensional multifluid simulation in a way directly comparable to the observations of the Plasma Experiment on the Galileo spacecraft. This is used to provide new insight to the existing controversy over the composition of Ganymede's observed ionospheric outflow, and enables further examination of the energetic signatures of the ion population trapped within Ganymede's magnetosphere. The model-predicted ionospheric outflow is consistent with the in situ ion energy spectrograms observed by the Galileo Plasma Experiment at closest approach, and requires that both ionospheric H+ and O+ are present in the population of ions exiting Ganymede's ionosphere over the polar cap. The outward flux of ionospheric ions was calculated to be ~1026 ions/cm2/s, which is in agreement with independently calculated sputtering rates of Ganymede's icy surface. The modeled spectrograms define characteristic energy signatures and populations for various regions of Ganymede's magnetosphere, which illustrate the major sources of ions trapped within the magnetosphere are Ganymede's ionospheric O+ and H+. The fact that very little plasma was observed inside Ganymede's magnetosphere during the G8 flyby is attributed to the region being shadowed from the sun for ~60 h, which may indicate the importance of photoionization for sustaining Ganymede's ionospheric plasma source.

Nonlinear dynamics of 3D beams of fast magnetosonic waves propagating in the ionospheric and magnetospheric plasma

NASA Astrophysics Data System (ADS)

Belashov, V. Yu.; Belashova, E. S.

2016-11-01

On the basis of the model of the three-dimensional (3D) generalized Kadomtsev-Petviashvili equation for magnetic field h = B / B the formation, stability, and dynamics of 3D soliton-like structures, such as the beams of fast magnetosonic (FMS) waves generated in ionospheric and magnetospheric plasma at a low-frequency branch of oscillations when β = 4 πnT/ B 2 ≪ 1 and β > 1, are studied. The study takes into account the highest dispersion correction determined by values of the plasma parameters and the angle θ = ( B, k), which plays a key role in the FMS beam propagation at those angles to the magnetic field that are close to π/2. The stability of multidimensional solutions is studied by an investigation of the Hamiltonian boundness under its deformations on the basis of solving of the corresponding variational problem. The evolution and dynamics of the 3D FMS wave beam are studied by the numerical integration of equations with the use of specially developed methods. The results can be interpreted in terms of the self-focusing phenomenon, as the formation of a stationary beam and the scattering and self-focusing of the solitary beam of FMS waves. These cases were studied with a detailed investigation of all evolutionary stages of the 3D FMS wave beams in the ionospheric and magnetospheric plasma.

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.

The Magnetosphere Imager Mission Concept Definition Study

NASA Technical Reports Server (NTRS)

Johnson, L.; Herrmann, M.; Alexander, Reggie; Beabout, Brent; Blevins, Harold; Bridge, Scott; Burruss, Glenda; Buzbee, Tom; Carrington, Connie; Chandler, Holly;

Physics of magnetospheric boundary layers

NASA Technical Reports Server (NTRS)

Cairns, I. H.

1993-01-01

The central ideas of this grant are that the magnetospheric boundary layers link disparate regions of the magnetosphere together, and the global behavior of the magnetosphere can be understood only by understanding the linking mechanisms. Accordingly the present grant includes simultaneous research on the global, meso-, and micro-scale physics of the magnetosphere and its boundary layers. These boundary layers include the bow shock, magnetosheath, the plasma sheet boundary layer, and the ionosphere. Analytic, numerical and simulation projects have been performed on these subjects, as well as comparison of theoretical results with observational data. Very good progress has been made, with four papers published or in press and two additional papers submitted for publication during the six month period 1 June - 30 November 1993. At least two projects are currently being written up. In addition, members of the group have given papers at scientific meetings. The further structure of this report is as follows: section two contains brief accounts of research completed during the last six months, while section three describes the research projects intended for the grant's final period.

An RCM-E simulation of a steady magnetospheric convection event

NASA Astrophysics Data System (ADS)

Yang, J.; Toffoletto, F.; Wolf, R.; Song, Y.

2009-12-01

We present simulation results of an idealized steady magnetospheric convection (SMC) event using the Rice Convection Model coupled with an equilibrium magnetic field solver (RCM-E). The event is modeled by placing a plasma distribution with substantially depleted entropy parameter PV5/3 on the RCM's high latitude boundary. The calculated magnetic field shows a highly depressed configuration due to the enhanced westward current around geosynchronous orbit where the resulting partial ring current is stronger and more symmetric than in a typical substorm growth phase. The magnitude of BZ component in the mid plasma sheet is large compared to empirical magnetic field models. Contrary to some previous results, there is no deep BZ minimum in the near-Earth plasma sheet. This suggests that the magnetosphere could transfer into a strong adiabatic earthward convection mode without significant stretching of the plasma-sheet magnetic field, when there are flux tubes with depleted plasma content continuously entering the inner magnetosphere from the mid-tail. Virtual AU/AL and Dst indices are also calculated using a synthetic magnetogram code and are compared to typical features in published observations.

Inner Magnetosphere Imager (IMI) instrument heritage

NASA Technical Reports Server (NTRS)

Wilson, G. R.

1993-01-01

This report documents the heritage of instrument concepts under consideration for the Inner Magnetosphere Imager (IMI) mission. The proposed IMI will obtain the first simultaneous images of the component regions of the inner magnetosphere and will enable scientists to relate these global images to internal and external influences as well as local observations. To obtain simultaneous images of component regions of the inner magnetosphere, measurements will be made of: (1) the ring current and inner plasma sheet using energetic neutral atoms; (2) the plasmasphere using extreme ultraviolet; (3) the electron and proton auroras using far ultraviolet and x rays; and (4) the geocorona using FUV. Instrument concepts that show heritage and traceability to those that will be required to meet the IMI measurement objectives are described.

Magnetic Reconnection and Associated Transient Phenomena Within the Magnetospheres of Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Louarn, Philippe; Andre, Nicolas; Jackman, Caitriona M.; Kasahara, Satoshi; Kronberg, Elena A.; Vogt, Marissa F.

2015-04-01

We review in situ observations made in Jupiter and Saturn's magnetosphere that illustrate the possible roles of magnetic reconnection in rapidly-rotating magnetospheres. In the Earth's solar wind-driven magnetosphere, the magnetospheric convection is classically described as a cycle of dayside opening and tail closing reconnection (the Dungey cycle). For the rapidly-rotating Jovian and Kronian magnetospheres, heavily populated by internal plasma sources, the classical concept (the Vasyliunas cycle) is that the magnetic reconnection plays a key role in the final stage of the radial plasma transport across the disk. By cutting and closing flux tubes that have been elongated by the rotational stress, the reconnection process would lead to the formation of plasmoids that propagate down the tail, contributing to the final evacuation of the internally produced plasma and allowing the return of the magnetic flux toward the planet. This process has been studied by inspecting possible `local' signatures of the reconnection, as magnetic field reversals, plasma flow anisotropies, energetic particle bursts, and more global consequences on the magnetospheric activity. The investigations made at Jupiter support the concept of an `average' X-line, extended in the dawn/dusk direction and located at 90-120 Jovian radius (RJ) on the night side. The existence of a similar average X-line has not yet been established at Saturn, perhaps by lack of statistics. Both at Jupiter and Saturn, the reconfiguration signatures are consistent with magnetospheric dipolarizations and formation of plasmoids and flux ropes. In several cases, the reconfigurations also appear to be closely associated with large scale activations of the magnetosphere, seen from the radio and auroral emissions. Nevertheless, the statistical study also suggests that the reconnection events and the associated plasmoids are not frequent enough to explain a plasma evacuation that matches the mass input rate from the

The Nonlinear Magnetosphere: Expressions in MHD and in Kinetic Models

NASA Technical Reports Server (NTRS)

Hesse, Michael; Birn, Joachim

2011-01-01

Like most plasma systems, the magnetosphere of the Earth is governed by nonlinear dynamic evolution equations. The impact of nonlinearities ranges from large scales, where overall dynamics features are exhibiting nonlinear behavior, to small scale, kinetic, processes, where nonlinear behavior governs, among others, energy conversion and dissipation. In this talk we present a select set of examples of such behavior, with a specific emphasis on how nonlinear effects manifest themselves in MHD and in kinetic models of magnetospheric plasma dynamics.

Kinetic models for space plasmas: Recent progress for the solar wind and the Earth's magnetosphere

NASA Astrophysics Data System (ADS)

Pierrard, V.; Moschou, S. P.; Lazar, M.; Borremans, K.; Rosson, G. Lopez

2016-11-01

Recent models for the solar wind and the inner magnetosphere have been developed using the kinetic approach. The solution of the evolution equation is used to determine the velocity distribution function of the particles and their moments. The solutions depend on the approximations and assumptions made in the development of the models. Effects of suprathermal particles often observed in space plasmas are taken into account to show their influence on the characteristics of the plasma, with specific applications for coronal heating and solar wind acceleration. We describe in particular the results obtained with the collisionless exospheric approximation based on the Lorentzian velocity distribution function for the electrons and its recent progress in three dimensions. The effects of Coulomb collisions obtained by using a Fokker-Planck term in the evolution equation were also investigated, as well as effects of the whistler wave turbulence at electron scale and the kinetic Alfven waves at the proton scale. For solar wind especially, modelling efforts with both magnetohydrodynamic and kinetic treatments have been compared and combined in order to improve the predictions in the vicinity of the Earth. Photospheric magnetograms serve as observational input in semi-empirical coronal models used for estimating the plasma characteristics up to coronal heliocentric distances taken as boundary conditions in solar wind models. The solar wind fluctuations may influence the dynamics of the space environment of the Earth and generate geomagnetic storms. In the magnetosphere of the Earth, the trajectories of the particles are simulated to study the plasmasphere, the extension of the ionosphere along closed magnetic field lines and to better understand the physical mechanisms involved in the radiation belts dynamics.

Electromagnetic and Radiative Properties of Neutron Star Magnetospheres

NASA Astrophysics Data System (ADS)

Li, Jason G.

2014-05-01

Magnetospheres of neutron stars are commonly modeled as either devoid of plasma in "vacuum'' models or filled with perfectly conducting plasma with negligible inertia in "force-free'' models. While numerically tractable, neither of these idealized 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. In this work we improve upon these models by considering the structure of magnetospheres filled with resistive plasma. We formulate Ohm's Law in the minimal velocity fluid frame and implement a time-dependent numerical code to construct a family of resistive solutions that smoothly bridges the gap between the vacuum and force-free magnetosphere solutions. We further apply our method to create a self-consistent model for the recently discovered intermittent pulsars that switch between two distinct states: an "on'', radio-loud state, and an "off'', radio-quiet state with lower spin-down luminosity. Essentially, we allow plasma to leak off open field lines in the absence of pair production in the "off'' state, reproducing observed differences in spin-down rates. Next, we examine models in which the high-energy emission from gamma-ray pulsars comes from reconnecting current sheets and layers near and beyond the light cylinder. The reconnected magnetic field provides a reservoir of energy that heats particles and can power high-energy synchrotron radiation. Emitting particles confined to the sheet naturally result in a strong caustic on the skymap and double peaked light curves for a broad range of observer angles. Interpulse bridge emission likely arises from interior to the light cylinder, along last open field lines that traverse the space between the polar caps and the current sheet. Finally, we apply our code to solve for the magnetospheric structure of merging neutron star binaries. We find that the scaling of electromagnetic

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.

Relativistic Dynamos in Magnetospheres of Rotating Compact Objects

NASA Astrophysics Data System (ADS)

Tomimatsu, Akira

2000-01-01

The kinematic evolution of axisymmetric magnetic fields in rotating magnetospheres of relativistic compact objects is analytically studied, based on relativistic Ohm's law in stationary axisymmetric geometry. By neglecting the poloidal flows of plasma in simplified magnetospheric models, we discuss a self-excited dynamo due to the frame-dragging effect (originally pointed out by Khanna & Camenzind) and propose alternative processes to generate axisymmetric magnetic fields against ohmic dissipation. The first process (which may be called ``induced excitation'') is caused by the help of a background uniform magnetic field in addition to the dragging of inertial frames. It is shown that excited multipolar components of poloidal and azimuthal fields are sustained as stationary modes, and outgoing Poynting flux converges toward the rotation axis. The second process is a self-excited dynamo through azimuthal convection current, which is found to be effective if plasma rotation becomes highly relativistic with a sharp gradient in the angular velocity. In this case, no frame-dragging effect is needed, and the coupling between charge separation and plasma rotation becomes important. We discuss briefly the results in relation to active phenomena in the relativistic magnetospheres.

A magnetospheric signature of some F layer positive storms

NASA Technical Reports Server (NTRS)

Miller, N. J.; Mayr, H. G.; Grebowsky, J. M.; Harris, I.; Tulunay, Y. K.

1981-01-01

Calculations of electron density distributions in the global thermosphere-ionosphere system perturbed by high-latitude thermospheric heating are presented which indicate a link between the heating and magnetospheric plasma disturbances near the equator. The calculations were made using a self-consistent model of the global sunlit thermosphere-ionosphere system describing the evolution of equatorial plasma disturbances. The heat input is found to cause electron density enhancements that propagate along magnetic field lines from the F2 maximum over mid-latitudes to the equator in the magnetosphere and which correspond to the positive phase of an F layer storm. The positive phase is shown to be generated by the induction of equatorward winds that raise the mid-latitude F layer through momentum transfer from neutral atoms to ionospheric ions, which ions pull electrons with them. Model results are used to identify plasma signatures of equatorward winds and an intensified magnetospheric electric field in Explorer 45 and Arial 4 measurements taken during the positive phase of an F layer storm.

Circulation of Heavy Ions and Their Dynamical Effects in the Magnetosphere: Recent Observations and Models

NASA Astrophysics Data System (ADS)

Kronberg, Elena A.; Ashour-Abdalla, Maha; Dandouras, Iannis; Delcourt, Dominique C.; Grigorenko, Elena E.; Kistler, Lynn M.; Kuzichev, Ilya V.; Liao, Jing; Maggiolo, Romain; Malova, Helmi V.; Orlova, Ksenia G.; Peroomian, Vahe; Shklyar, David R.; Shprits, Yuri Y.; Welling, Daniel T.; Zelenyi, Lev M.

2014-11-01

Knowledge of the ion composition in the near-Earth's magnetosphere and plasma sheet is essential for the understanding of magnetospheric processes and instabilities. The presence of heavy ions of ionospheric origin in the magnetosphere, in particular oxygen (O+), influences the plasma sheet bulk properties, current sheet (CS) thickness and its structure. It affects reconnection rates and the formation of Kelvin-Helmholtz instabilities. This has profound consequences for the global magnetospheric dynamics, including geomagnetic storms and substorm-like events. The formation and demise of the ring current and the radiation belts are also dependent on the presence of heavy ions. In this review we cover recent advances in observations and models of the circulation of heavy ions in the magnetosphere, considering sources, transport, acceleration, bulk properties, and the influence on the magnetospheric dynamics. We identify important open questions and promising avenues for future research.

Effect of self-consistent magnetic field on plasma sheet penetration to the inner magnetosphere under enhanced convection: RCM simulations combined with force-balance magnetic field solver

NASA Astrophysics Data System (ADS)

Gkioulidou, M.; Wang, C.; Lyons, L. R.; Wolf, R. A.

2010-12-01

Transport of plasma sheet particles into the inner magnetosphere is strongly affected by the penetration of the convection electric field, which is the result of the large-scale magnetosphere-ionosphere electromagnetic coupling. This transport, on the other hand, results in plasma heating and magnetic field stretching, which become very significant in the inner plasma sheet (inside 20 RE). We have previously run simulations with the Rice Convection Model (RCM) to investigate how the earthward penetration of convection electric field, and therefore plasma sheet population, depends on plasma sheet boundary conditions. Outer boundary conditions at r ~20 RE are a function of MLT and interplanetary conditions based on 11 years of Geotail data. In the previous simulations, Tsyganenko 96 magnetic field model (T96) was used so force balance between plasma pressure and magnetic fields was not maintained. We have now integrated the RCM with a magnetic field solver (Liu et al., 2006) to obtain the required force balance in the equatorial plane. We have run the self-consistent simulations under enhanced convection with different boundary conditions in which we kept different parameters (flux tube particle content, plasma pressure, plasma beta, or magnetic fields) at the outer boundary to be MLT-dependent but time independent. Different boundary conditions result in qualitatively similar plasma sheet profiles. The results show that magnetic field has a dawn dusk asymmetry with field lines being more stretched in the pre-midnight sector, due to relatively higher plasma pressure there. The asymmetry in the magnetic fields in turn affects the radial distance and MLT of plasma sheet penetration into the inner magnetosphere. In comparison with results using the T96, plasma transport under self-consistent magnetic field results in proton and electron plasma sheet inner edges that are located in higher latitudes, weaker pressure gradients, and more efficient shielding of the near

A parametric study of the linear growth of magnetospheric EMIC waves in a hot plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qi; Cao, Xing; Gu, Xudong, E-mail: guxudong@whu.edu.cn, E-mail: bbni@whu.edu.cn

2016-06-15

Since electromagnetic ion cyclotron (EMIC) waves in the terrestrial magnetosphere play a crucial role in the dynamic losses of relativistic electrons and energetic protons and in the ion heating, it is important to pursue a comprehensive understanding of the EMIC wave dispersion relation under realistic circumstances, which can shed significant light on the generation, amplification, and propagation of magnetospheric EMIC waves. The full kinetic linear dispersion relation is implemented in the present study to evaluate the linear growth of EMIC waves in a multi-ion (H{sup +}, He{sup +}, and O{sup +}) magnetospheric plasma that also consists of hot ring currentmore » protons. Introduction of anisotropic hot protons strongly modifies the EMIC wave dispersion surface and can result in the simultaneous growth of H{sup +}-, He{sup +}-, and O{sup +}-band EMIC emissions. Our parametric analysis demonstrates that an increase in the hot proton concentration can produce the generation of H{sup +}- and He{sup +}-band EMIC waves with higher possibility. While the excitation of H{sup +}-band emissions requires relatively larger temperature anisotropy of hot protons, He{sup +}-band emissions are more likely to be triggered in the plasmasphere or plasmaspheric plume where the background plasma is denser. In addition, the generation of He{sup +}-band waves is more sensitive to the variation of proton temperature than H{sup +}-band waves. Increase of cold heavy ion (He{sup +} and O{sup +}) density increases the H{sup +} cutoff frequency and therefore widens the frequency coverage of the stop band above the He{sup +} gyrofrequency, leading to a significant damping of H{sup +}-band EMIC waves. In contrast, O{sup +}-band EMIC waves characteristically exhibit the temporal growth much weaker than the other two bands, regardless of all considered variables, suggesting that O{sup +}-band emissions occur at a rate much lower than H{sup +}- and He{sup +}-band emissions, which is

The impact of comet Shoemaker-Levy 9 on the Jovian magnetosphere

NASA Technical Reports Server (NTRS)

Herbert, Floyd

1994-01-01

By the time of the impact of comet P/Shoemaker-Levy 9 with Jupiter, the freshly-broken surfaces of the accompanying rubble will have been outgassing for about two years, and will have produced an expanding and co-moving cloud of gas hundreds of R(sub J) across. Much of this gas, escaping from the cometary fragments at low (equal to or less than 1 km/s) speed, will arrive in the Jovian magnetopshere contemporaneously with the comet and drift through the magnetosphere. This gas, as it is photoionized, will be picked up primarily in the outer magnetosphere and the resulting high-energy ions should intensify magnetospheric processes, such as Io plasma torus and auroral emissions, that are thought to be powered by outer magnetospheric mass loading. If the composition of the comet is similar to that of P/Halley, the power available from mass loading should be comparable to that driving the aurora (10(exp 14) W) and at least an order of magnitude larger than that exciting the plasma torus for several weeks or months. Measurement of these emissions during and after the cometary encounter may constrain the mechanisms for energization of magnetospheric charged particle populations and magnetospheric transport processes.

Energy coupling in the magnetospheres of earth and Mercury

NASA Technical Reports Server (NTRS)

Baker, D. N.

1990-01-01

The mechanisms involved in the dissipation of solar-wind energy during magnetospheric substorms are considered theoretically, comparing models for earth and Mercury. In the model for terrestrial substorms, IMF lines interconnect with terrestrial field lines near the front of the magnetosphere and are dragged back, carrying plasma and energy, to form tail lobes; a magnetic neutral region is then formed by reconnection of the open lines as the plasma sheet thins, and reconnective heating and acceleration of tail plasma lead to plasma inflow at the poles and formation of a plasmoid flowing down the tail at high velocity. Analogous phenomena on Mercury could produce precipitation of particles carrying 10-1000 GW of power into 'auroral zones' on the dark side of the planet. The feasibility of remote or in situ observations to detect such processes is discussed.

Dawn-dusk asymmetries in rotating magnetospheres: Lessons from modeling Saturn

NASA Astrophysics Data System (ADS)

Jia, Xianzhe; Kivelson, Margaret G.

2016-02-01

Spacecraft measurements reveal perplexing dawn-dusk asymmetries of field and plasma properties in the magnetospheres of Saturn and Jupiter. Here we describe a previously unrecognized source of dawn-dusk asymmetry in a rapidly rotating magnetosphere. We analyze two magnetohydrodynamic simulations, focusing on how flows along and across the field vary with local time in Saturn's dayside magnetosphere. As plasma rotates from dawn to noon on a dipolarizing flux tube, it flows away from the equator along the flux tube at roughly half of the sound speed (Cs), the maximum speed at which a bulk plasma can flow along a flux tube into a lower pressure region. As plasma rotates from noon to dusk on a stretching flux tube, the field-aligned component of its centripetal acceleration decreases and it flows back toward the equator at speeds typically smaller than 1/2 Cs. Correspondingly, the plasma sheet remains far thicker and the field less stretched in the afternoon than in the morning. Different radial force balance in the morning and afternoon sectors produce asymmetry in the plasma sheet thickness and a net dusk-to-dawn flow inside of L = 15 or equivalently, a large-scale electric field (E) oriented from postnoon to premidnight, as reported from observations. Morning-afternoon asymmetry analogous to that found at Saturn has been observed at Jupiter, and a noon-midnight component of E cannot be ruled out.

REVIEWS OF TOPICAL PROBLEMS: Magnetospheres of planets with an intrinsic magnetic field

NASA Astrophysics Data System (ADS)

Belenkaya, Elena S.

2009-08-01

This review presents modern views on the physics of magnetospheres of Solar System planets having an intrinsic magnetic field, and on the structure of magnetospheric magnetic fields. Magnetic fields are generated in the interiors of Mercury, Earth, Jupiter, Saturn, Uranus, and Neptune via the dynamo mechanism. These fields are so strong that they serve as obstacles for the plasma stream of the solar wind. A magnetosphere surrounding a planet forms as the result of interaction between the solar wind and the planetary magnetic field. The dynamics of magnetospheres are primary enforced by solar wind variations. Each magnetosphere is unique. The review considers common and individual sources of magnetic fields and the properties of planetary magnetospheres.

Energetic particle pressure in Saturn's magnetosphere measured with the Magnetospheric Imaging Instrument on Cassini

NASA Astrophysics Data System (ADS)

Sergis, N.; Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Krupp, N.; Mauk, B. H.; Roelof, E. C.; Dougherty, M. K.

2009-02-01

The Magnetospheric Imaging Instrument on board Cassini has been providing measurements of energetic ion intensities, energy spectra, and ion composition, combining the Charge Energy Mass Spectrometer over the range 3 to 236 keV/e, the Low Energy Magnetospheric Measurements System for ions in the range 0.024 to 18 MeV, and the Ion and Neutral Camera for ions and energetic neutral atoms in the range 3 to > 200 keV. Results of the energetic (E > 3 keV) particle pressure distribution throughout the Saturnian magnetosphere and comparison with in situ measurements of the magnetic pressure are presented. The study offers a comprehensive depiction of the average, steady state hot plasma environment of Saturn over the 3 years since orbit insertion on 1 July 2004, with emphasis on ring current characteristics. The results may be summarized as follows: (1) The Saturnian magnetosphere possesses a dynamic, high-beta ring current located approximately between 8 and ~15 RS, primarily composed of O+ ions, and characterized by suprathermal (E > 3 keV) particle pressure, with typical values of 10-9 dyne/cm2. (2) The planetary plasma sheet shows significant asymmetries, with the dayside region being broadened in latitude (+/-50°) and extending to the magnetopause, and the nightside appearing well confined, with a thickness of ~10 RS and a northward tilt of some 10° with respect to the equatorial plane beyond ~20 RS. (3) The average radial suprathermal pressure gradient appears sufficient to modify the radial force balance and subsequently the azimuthal currents. (4) The magnetic perturbation due to the trapped energetic particle population is ~7 nT, similar to values from magnetic field-based studies (9 to 13 nT).

Plasma Turbulence in Earth's Magnetotail Observed by the Magnetospheric Multiscale Mission

NASA Astrophysics Data System (ADS)

Mackler, D. A.; Avanov, L. A.; Boardsen, S. A.; Pollock, C. J.

2017-12-01

Magnetic reconnection, a process in which the magnetic topology undergoes multi-scale changes, is a significant mechanism for particle energization as well as energy dissipation. Reconnection is observed to occur in thin current sheets generated between two regions of magnetized plasma merging with a non-zero shear angle. Within a thinning current sheet, the dominant scale size approaches first the ion and then electron kinetic scale. The plasma becomes demagnetized, field lines transform, then once again the plasma becomes frozen-in. The reconnection process accelerates particles, leading to heated jets of plasma. Turbulence is another fundamental process in collision less plasmas. Despite decades of turbulence studies, an essential science question remains as to how turbulent energy dissipates at small scales by heating and accelerating particles. Turbulence in both plasmas and fluids has a fundamental property in that it follows an energy cascade into smaller scales. Energy introduced into a fluid or plasma can cause large scale motion, introducing vorticity, which merge and interact to make increasingly smaller eddies. It has been hypothesized that turbulent energy in magnetized plasmas may be dissipated by magnetic reconnection, just as viscosity dissipates energy in neutral fluid turbulence. The focus of this study is to use the new high temporal resolution suite of instruments on board the Magnetospheric MultiScale (MMS) mission to explore this hypothesis. An observable feature of the energy cascade in a turbulent magnetized plasma is its similarity to classical hydrodynamics in that the Power Spectral Density (PSD) of turbulent fluctuations follows a Kolmogorov-like power law (Image-5/3). We use highly accurate (0.1 nT) Flux Gate Magnetometer (FGM) data to derive the PSD as a function of frequency in the magnetic fluctuations. Given that we are able to confirm the turbulent nature of the flow field; we apply the method of Partial Variance of Increments (PVI

A Census of Plasma Waves and Structures Associated With an Injection Front in the Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Malaspina, David M.; Ukhorskiy, Aleksandr; Chu, Xiangning; Wygant, John

2018-04-01

Now that observations have conclusively established that the inner magnetosphere is abundantly populated with kinetic electric field structures and nonlinear waves, attention has turned to quantifying the ability of these structures and waves to scatter and accelerate inner magnetospheric plasma populations. A necessary step in that quantification is determining the distribution of observed structure and wave properties (e.g., occurrence rates, amplitudes, and spatial scales). Kinetic structures and nonlinear waves have broadband signatures in frequency space, and consequently, high-resolution time domain electric and magnetic field data are required to uniquely identify such structures and waves as well as determine their properties. However, most high-resolution fields data are collected with a strong bias toward high-amplitude signals in a preselected frequency range, strongly biasing observations of structure and wave properties. In this study, an ˜45 min unbroken interval of 16,384 samples/s field burst data, encompassing an electron injection event, is examined. This data set enables an unbiased census of the kinetic structures and nonlinear waves driven by this electron injection, as well as determination of their "typical" properties. It is found that the properties determined using this unbiased burst data are considerably different than those inferred from amplitude-biased burst data, with significant implications for wave-particle interactions due to kinetic structures and nonlinear waves in the inner magnetosphere.

An Introduction to Magnetospheric Physics by Means of Simple Models

NASA Technical Reports Server (NTRS)

Stern, D. P.

1981-01-01

The large scale structure and behavior of the Earth's magnetosphere is discussed. The model is suitable for inclusion in courses on space physics, plasmas, astrophysics or the Earth's environment, as well as for self-study. Nine quantitative problems, dealing with properties of linear superpositions of a dipole and a constant field are presented. Topics covered include: open and closed models of the magnetosphere; field line motion; the role of magnetic merging (reconnection); magnetospheric convection; and the origin of the magnetopause, polar cusps, and high latitude lobes.

Particle-in-Cell Simulations of the Twisted Magnetospheres of Magnetars. I.

NASA Astrophysics Data System (ADS)

Chen, Alexander Y.; Beloborodov, Andrei M.

2017-08-01

The magnetospheres of magnetars are believed to be filled with electron-positron plasma generated by electric discharge. We present a first numerical experiment demonstrating this process in an axisymmetric magnetosphere with a simple threshold prescription for pair creation, which is applicable to the inner magnetosphere with an ultrastrong field. The {e}+/- discharge occurs in response to the twisting of the closed magnetic field lines by a shear deformation of the magnetar surface, which launches electric currents into the magnetosphere. The simulation shows the formation of an electric “gap” with an unscreened electric field ({\\boldsymbol{E}}\\cdot {\\boldsymbol{B}}\

Origin and maintenance of the oxygen torus in Saturn's magnetosphere

NASA Technical Reports Server (NTRS)

Morfill, G. E.; Havnes, O.; Goertz, C. K.

1993-01-01

Observations of thermal ions in Saturn's inner magnetosphere suggest distributed local sources rather than diffusive mass loading from a source located further out. We suggest that the plasma is produced and maintained mainly by 'self-sputtering' of E ring dust. Sputtered particles are 'picked up' by the planetary magnetospheric field and accelerated to corotation energies (of the order of 8 eV/amu). The sputter yield for oxygen on ice at, for example, 120 eV is about 5, which implies that an avalanche of self-sputtering occurs. The plasma density is built up until it is balanced by local losses, presumably pitch angle scattering into the loss cone and absorption in the planet's ionosphere. The plasma density determines the distribution of dust in the E ring through plasma drag. Thus a feedback mechanism between the plasma and the E ring dust is established. The model accounts for the principal plasma observations and simultaneously the radial optical depth profile of the E ring.

History of Los Alamos Participation in Active Experiments in Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pongratz, Morris B.

Beginning with the Teak nuclear test in 1958, Los Alamos has a long history of participation in active experiments in space. The last pertinent nuclear tests were the five explosions as part of the Dominic series in 1962. The Partial Test Ban Treaty signed in August 1963 prohibited all test detonations of nuclear weapons except for those conducted underground. Beginning with the “Apple” thermite barium release in June 1968 Los Alamos has participated in nearly 100 non-nuclear experiments in space, the last being the NASA-sponsored “AA-2” strontium and europium doped barium thermite releases in the Arecibo beam in July ofmore » 1992. The rationale for these experiments ranged from studying basic plasma processes such as gradientdriven structuring and velocity-space instabilities to illuminating the convection of plasmas in the ionosphere and polar cap to ionospheric depletion experiments to the B.E.A.R. 1-MeV neutral particle beam test in 1989. This report reviews the objectives, techniques and diagnostics of Los Alamos participation in active experiments in space.« less

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.

Large-scale solar wind flow around Saturn's nonaxisymmetric magnetosphere

NASA Astrophysics Data System (ADS)

Sulaiman, A. H.; Jia, X.; Achilleos, N.; Sergis, N.; Gurnett, D. A.; Kurth, W. S.

2017-09-01

The interaction between the solar wind and a magnetosphere is central to the dynamics of a planetary system. Here we address fundamental questions on the large-scale magnetosheath flow around Saturn using a 3-D magnetohydrodynamic (MHD) simulation. We find Saturn's polar-flattened magnetosphere to channel 20% more flow over the poles than around the flanks at the terminator. Further, we decompose the MHD forces responsible for accelerating the magnetosheath plasma to find the plasma pressure gradient as the dominant driver. This is by virtue of a high-β magnetosheath and, in turn, the high-MA bow shock. Together with long-term magnetosheath data by the Cassini spacecraft, we present evidence of how nonaxisymmetry substantially alters the conditions further downstream at the magnetopause, crucial for understanding solar wind-magnetosphere interactions such as reconnection and shear flow-driven instabilities. We anticipate our results to provide a more accurate insight into the global conditions upstream of Saturn and the outer planets.

Solar wind and magnetosphere interactions

NASA Technical Reports Server (NTRS)

Russell, C. T.; Allen, J. H.; Cauffman, D. P.; Feynman, J.; Greenstadt, E. W.; Holzer, R. E.; Kaye, S. M.; Slavin, J. A.; Manka, R. H.; Rostoker, G.

1979-01-01

The relationship between the magnetosphere and the solar wind is addressed. It is noted that this interface determines how much of the solar plasma and field energy is transferred to the Earth's environment, and that this coupling not only varies in time, responding to major solar disturbances, but also to small changes in solar wind conditions and interplanetary field directions. It is recommended that the conditions of the solar wind and interplanetary medium be continuously monitored, as well as the state of the magnetosphere. Other recommendations include further study of the geomagnetic tail, tests of Pc 3,4 magnetic pulsations as diagnostics of the solar wind, and tests of kilometric radiation as a remote monitor of the auroral electrojet.

The influence of centrifugal forces on the B field structure of an axially symmetric equilibrium magnetosphere

NASA Technical Reports Server (NTRS)

Ye, Gang; Voigt, Gerd-Hannes

1989-01-01

A model is presented of an axially symmetric pole-on magnetosphere in MHD force balance, in which both plasma thermal pressure gradients and centrifugal force are taken into account. Assuming that planetary rotation leads to differentially rotating magnetotail field lines, the deformation of magnetotail field lines under the influence of both thermal plasma pressure and centrifugal forces was calculated. Analytic solutions to the Grad-Shafranov equation are presented, which include the centrifugal force term. It is shown that the nonrotational magnetosphere with hot thermal plasma leads to a field configuration without a toroidal B(phi) component and without field-aligned Birkeland currents. The other extreme, a rapidly rotating magnetosphere with cold plasma, leads to a configuration in which plasma must be confined within a thin disk in a plane where the radial magnetic field component B(r) vanishes locally.

Toward a closer integration of magnetospheric research: Magnetospheric currents inferred from ground-based magnetic data

NASA Astrophysics Data System (ADS)

Akasofu, S.-I.; Kamide, Y.

1998-07-01

A new approach is needed to advance magnetospheric physics in the future to achieve a much closer integration than in the past among satellite-based researchers, ground-based researchers, and theorists/modelers. Specifically, we must find efficient ways to combine two-dimensional ground-based data and single points satellite-based data to infer three-dimensional aspects of magnetospheric disturbances. For this particular integration purpose, we propose a new project. It is designed to determine the currents on the magnetospheric equatorial plane from the ionospheric current distribution which has become available by inverting ground-based magnetic data from an extensive, systematic network of observations, combined with ground-based radar measurements of ionospheric parameters, and satellite observations of auroras, electric fields, and currents. The inversion method is based on the KRM/AMIE algorithms. In the first part of the paper, we extensively review the reliability and accuracy of the KRM and AMIE algorithms and conclude that the ionospheric quantities thus obtained are accurate enough for the next step. In the second part, the ionospheric current distribution thus obtained is projected onto the equatorial plane. This process requires a close cooperation with modelers in determining an accurate configuration of the magnetospheric field lines. If we succeed in this projection, we should be able to study the changing distribution of the currents in a vast region of the magnetospheric equatorial plane for extended periods with a time resolution of about 5 min. This process requires a model of the magnetosphere for the different phases of the magnetospheric substorm. Satellite-based observations are needed to calibrate the projection results. Agreements and disagreements thus obtained will be crucial for theoretical studies of magnetospheric plasma convection and dynamics, particularly in studying substorms. Nothing is easy in these procedures. However, unless

The UAH Spinning Terrella Experiment: A Laboratory Analog for the Earth's Magnetosphere

NASA Technical Reports Server (NTRS)

Sheldon, R. B.; Gallagher, D. L.; Craven, P. D.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The UAH Spinning Terrella Experiment has been modified to include the effect of a second magnet. This is a simple laboratory demonstration of the well-known double-dipole approximation to the Earth's magnetosphere. In addition, the magnet has been biassed $\\sim$-400V which generates a DC glow discharge and traps it in a ring current around the magnet. This ring current is easily imaged with a digital camera and illustrates several significant topological properties of a dipole field. In particular, when the two dipoles are aligned, and therefore repel, they emulate a northward IMF Bz magnetosphere. Such a geometry traps plasma in the high latitude cusps as can be clearly seen in the movies. Likewise, when the two magnets are anti-aligned, they emulate a southward IMF Bz magnetosphere with direct feeding of plasma through the x-line. We present evidence for trapping and heating of the plasma, comparing the dipole-trapped ring current to the cusp-trapped population. We also present a peculiar asymmetric ring current produced in by the plasma at low plasma densities. We discuss the similarities and dissimilarities of the laboratory analog to the collisionless Earth plasma, and implications for the interpretation of IMAGE data.

MAVEN Observations of Magnetic Reconnection on the Dayside Martian Magnetosphere

NASA Astrophysics Data System (ADS)

DiBraccio, Gina A.; Espley, Jared R.; Connerney, John E. P.; Brain, David A.; Halekas, Jasper S.; Mitchell, David L.; Harada, Yuki; Hara, Takuya

2015-04-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission offers a unique opportunity to investigate the complex solar wind-planetary interaction at Mars. The Martian magnetosphere is formed as the interplanetary magnetic field (IMF) drapes around the planet's ionosphere and localized crustal magnetic fields. As the solar wind interacts with this induced magnetosphere, magnetic reconnection can occur at any location where a magnetic shear is present. Reconnection between the IMF and the induced and crustal fields facilitates a direct plasma exchange between the solar wind and the Martian ionosphere. Here we address the occurrence of magnetic reconnection on the dayside magnetosphere of Mars using MAVEN magnetic field and plasma data. When reconnection occurs on the dayside, a non-zero magnetic field component normal to the obstacle, B_N, will result. Using minimum variance analysis, we measure BN by transforming Magnetometer data into boundary-normal coordinates. Selected events are then further examined to identify plasma heating and energization, in the form of Alfvénic outflow jets, using Solar Wind Ion Analyzer measurements. Additionally, the topology of the crustal fields is validated from electron pitch angle distributions provided by the Solar Wind Electron Analyzer. To understand which parameters are responsible for the onset of reconnection, we test the dependency of the dimensionless reconnection rate, calculated from BN measurements, on magnetic field shear angle and plasma beta (the ratio of plasma pressure to magnetic pressure). We assess the global impact of reconnection on Mars' induced magnetosphere by combining analytical models with MAVEN observations to predict the regions where reconnection may occur. Using this approach we examine how IMF orientation and magnetosheath parameters affect reconnection on a global scale. With the aid of analytical models we are able to assess the role of reconnection on a global scale to better understand which

The outer magnetosphere. [composition and comparison with earth

NASA Technical Reports Server (NTRS)

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

1984-01-01

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.

Energy and Mass Transport of Magnetospheric Plasmas during the November 2003 Magnetic Storm

NASA Technical Reports Server (NTRS)

Fok, Mei-Chging; Moore, Thomas

2008-01-01

Intensive energy and mass transport from the solar wind across the magnetosphere boundary is a trigger of magnetic storms. The storm on 20-21 November 2003 was elicited by a high-speed solar wind and strong southward component of interplanetary magnetic field. This storm attained a minimum Dst of -422 nT. During the storm, some of the solar wind particles enter the magnetosphere and eventually become part of the ring current. At the same time, the fierce solar wind powers strong outflow of H+ and O+ from the ionosphere, as well as from the plasmasphere. We examine the contribution of plasmas from the solar wind, ionosphere and plasmasphere to the storm-time ring current. Our simulation shows, for this particular storm, ionospheric O+ and solar wind ions are the major sources of the ring current particles. The polar wind and plasmaspheric H+ have only minor impacts. In the storm main phase, the strong penetration of solar wind electric field pushes ions from the geosynchronous orbit to L shells of 2 and below. Ring current is greatly intensified during the earthward transport and produces a large magnetic depression in the surface field. When the convection subsides, the deep penetrating ions experience strong charge exchange loss, causing rapid decay of the ring current and fast initial storm recovery. Our simulation reproduces very well the storm development indicated by the Dst index.

Modelling of auroral electrodynamical processes: Magnetosphere to mesosphere

NASA Technical Reports Server (NTRS)

Chiu, Y. T.; Gorney, D. J.; Kishi, A. M.; Newman, A. L.; Schulz, M.; Walterscheid, R. L.; CORNWALL; Prasad, S. S.

1982-01-01

Research conducted on auroral electrodynamic coupling between the magnetosphere and ionosphere-atmosphere in support of the development of a global scale kinetic plasma theory is reviewed. Topics covered include electric potential structure in the evening sector; morning and dayside auroras; auroral plasma formation; electrodynamic coupling with the thermosphere; and auroral electron interaction with the atmosphere.

Particle-in-cell Simulations of Waves in a Plasma Described by Kappa Velocity Distribution as Observed in the Saturńs Magnetosphere

NASA Astrophysics Data System (ADS)

Alves, M. V.; Barbosa, M. V. G.; Simoes, F. J. L., Jr.

2016-12-01

Observations have shown that several regions in space plasmas exhibit non-Maxwellian distributions with high energy superthermal tails. Kappa velocity distribution functions can describe many of these regions and have been used since the 60's. They suit well to represent superthermal tails in solar wind as well as to obtain plasma parameters of plasma within planetary magnetospheres. A set of initial velocities following kappa distribution functions is used in KEMPO1 particle simulation code to analyze the normal modes of wave propagation. Initial conditions are determined using observed characteristics for Saturńs magnetosphere. Two electron species with different temperatures and densities and ions as a third species are used. Each electron population is described by a different kappa index. Particular attention is given to perpendicular propagation, Bernstein modes, and parallel propagation, Langmuir and electron-acoustic modes. The dispersion relation for the Bernstein modes is strongly influenced by the shape of the velocity distribution and consequently by the value of kappa index. Simulation results are compared with numerical solutions of the dispersion relation obtained in the literature and they are in good agreement.

Self-Consistent Large-Scale Magnetosphere-Ionosphere Coupling: Computational Aspects and Experiments

NASA Technical Reports Server (NTRS)

Newman, Timothy S.

2003-01-01

Both external and internal phenomena impact the terrestrial magnetosphere. For example, solar wind and particle precipitation effect the distribution of hot plasma in the magnetosphere. Numerous models exist to describe different aspects of magnetosphere characteristics. For example, Tsyganenko has developed a series of models (e.g., [TSYG89]) that describe the magnetic field, and Stern [STER75] and Volland [VOLL73] have developed an analytical model that describes the convection electric field. Over the past several years, NASA colleague Khazanov, working with Fok and others, has developed a large-scale coupled model that tracks particle flow to determine hot ion and electron phase space densities in the magnetosphere. This model utilizes external data such as solar wind densities and velocities and geomagnetic indices (e.g., Kp) to drive computational processes that evaluate magnetic, electric field, and plasma sheet models at any time point. These models are coupled such that energetic ion and electron fluxes are produced, with those fluxes capable of interacting with the electric field model. A diagrammatic representation of the coupled model is shown.

Electromagnetic and electrostatic emissions at the cusp-magnetosphere interface during substorms

NASA Technical Reports Server (NTRS)

Curtis, S. A.; Fairfield, D. H.; Wu, C. S.

1979-01-01

Strongly peaked electrostatic emissions near 10.0 kHz and electromagnetic emissions near 0.56 kHz have been observed by the VLF wave detector on board Imp 6 on crossings from the earth's magnetosphere into the polar cusp during the occurrence of large magnetospheric substorms. The electrostatic emissions were observed to be closely confined to the cusp-magnetosphere interface. The electromagnetic emissions were of somewhat broader spatial extent and were seen on higher-latitude field lines within the cusp. Using these plasma wave observations and additional information provided by plasma, magnetometer and particle measurements made simultaneously on Imp 6, theories are constructed to explain each of the two classes of emission. The electromagnetic waves are modeled as whistlers, and the electrostatic waves as electron-cyclotron harmonics. The resulting growth rates predict power spectra similar to those observed for both emission classes. The electrostatic waves may play a significant role via enhanced diffusion in the relaxation of the sharp substorm time cusp-magnetosphere boundary to a more diffuse quiet time boundary.

Multi-Fluid Simulations of a Coupled Ionosphere-Magnetosphere System

NASA Astrophysics Data System (ADS)

Gombosi, T. I.; Glocer, A.; Toth, G.; Ridley, A. J.; Sokolov, I. V.; de Zeeuw, D. L.

2008-05-01

In the last decade we have developed the Space Weather Modeling Framework (SWMF) that efficiently couples together different models describing the interacting regions of the space environment. Many of these domain models (such as the global solar corona, the inner heliosphere or the global magnetosphere) are based on MHD and are represented by our multiphysics code, BATS-R-US. BATS-R-US can solve the equations of "standard" ideal MHD, but it can also go beyond this first approximation. It can solve resistive MHD, Hall MHD, semi-relativistic MHD (that keeps the displacement current), multispecies (different ion species have different continuity equations) and multifluid (all ion species have separate continuity, momentum and energy equations) MHD. Recently we added two-fluid Hall MHD (solving the electron and ion energy equations separately) and are working on an extended magnetohydrodynamics model with anisotropic pressures. Ionosheric outflow can be a significant contributor to the plasma population of the magnetosphere during active geomagnetic conditions. This talk will present preliminary results of our simulations when we couple a new field- aligned multi-fluid polar wind code to the Ionosphere Electrodynamics (IE), and Global Magnetosphere (GM) components of the SWMF. We use multi-species and multi-fluid MHD to track the resulting plasma composition in the magnetosphere.

Existence of steady gap solutions in rotating black hole magnetospheres

NASA Astrophysics Data System (ADS)

Levinson, Amir; Segev, Noam

2017-12-01

Under conditions prevailing in certain classes of compact astrophysical systems, the active magnetosphere of a rotating black hole becomes charge starved, giving rise to the formation of a spark gap in which plasma is continuously produced. The plasma production process is accompanied by curvature and inverse Compton emission of gamma rays in the GeV-TeV band, which may be detectable by current and future experiments. The properties of the gap emission have been studied recently using a fully general-relativistic model of a local steady gap. However, this model requires artificial adjustment of the electric current which is determined, in reality, by the global properties of the magnetosphere. In this paper we map the parameter regime in which steady gap solutions exist, using a steady-state gap model in Kerr geometry, and show that such solutions are allowed only under restrictive conditions that may not apply to most astrophysical systems. We further argue that even the allowed solutions are inconsistent with the global magnetospheric structure. We conclude that magnetospheric gaps are inherently intermittent, and point out that this may drastically change their emission properties.

Shape of the terrestrial plasma sheet in the near-Earth magnetospheric tail as imaged by the Interstellar Boundary Explorer

DOE PAGES

Dayeh, M. A.; Fuselier, S. A.; Funsten, H. O.; ...

2015-04-11

We present remote, continuous observations from the Interstellar Boundary Explorer of the terrestrial plasma sheet location back to -16 Earth radii (R E) in the magnetospheric tail using energetic neutral atom emissions. The time period studied includes two orbits near the winter and summer solstices, thus associated with large negative and positive dipole tilt, respectively. Continuous side-view images reveal a complex shape that is dominated mainly by large-scale warping due to the diurnal motion of the dipole axis. Superposed on the global warped geometry are short-time fluctuations in plasma sheet location that appear to be consistent with plasma sheet flappingmore » and possibly twisting due to changes in the interplanetary conditions. We conclude that the plasma sheet warping due to the diurnal motion dominates the average shape of the plasma sheet. Over short times, the position of the plasma sheet can be dominated by twisting and flapping.« less

Plasma Sheet Circulation Pathways

NASA Technical Reports Server (NTRS)

Moore, Thomas E.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A.; Damiano, P.; Lotko, W.

2008-01-01

Global simulations of Earth's magnetosphere in the solar wind compute the pathways of plasma circulation through the plasma sheet. We address the pathways that supply and drain the plasma sheet, by coupling single fluid simulations with Global Ion Kinetic simulations of the outer magnetosphere and the Comprehensive Ring Current Model of the inner magnetosphere, including plasmaspheric plasmas. We find that the plasma sheet is supplied with solar wind plasmas via the magnetospheric flanks, and that this supply is most effective for northward IMF. For southward IMF, the innermost plasma sheet and ring current region are directly supplied from the flanks, with an asymmetry of single particle entry favoring the dawn flank. The central plasma sheet (near midnight) is supplied, as expected, from the lobes and polar cusps, but the near-Earth supply consists mainly of slowly moving ionospheric outflows for typical conditions. Work with the recently developed multi-fluid LFM simulation shows transport via plasma "fingers" extending Earthward from the flanks, suggestive of an interchange instability. We investigate this with solar wind ion trajectories, seeking to understand the fingering mechanisms and effects on transport rates.

One ring to rule them all: storm time ring current and its influence on radiation belts, plasmasphere and global magnetosphere electrodynamics

NASA Astrophysics Data System (ADS)

Buzulukova, Natalia; Fok, Mei-Ching; Glocer, Alex; Moore, Thomas E.

2013-04-01

We report studies of the storm time ring current and its influence on the radiation belts, plasmasphere and global magnetospheric dynamics. The near-Earth space environment is described by multiscale physics that reflects a variety of processes and conditions that occur in magnetospheric plasma. For a successful description of such a plasma, a complex solution is needed which allows multiple physics domains to be described using multiple physical models. A key population of the inner magnetosphere is ring current plasma. Ring current dynamics affects magnetic and electric fields in the entire magnetosphere, the distribution of cold ionospheric plasma (plasmasphere), and radiation belts particles. To study electrodynamics of the inner magnetosphere, we present a MHD model (BATSRUS code) coupled with ionospheric solver for electric field and with ring current-radiation belt model (CIMI code). The model will be used as a tool to reveal details of coupling between different regions of the Earth's magnetosphere. A model validation will be also presented based on comparison with data from THEMIS, POLAR, GOES, and TWINS missions. INVITED TALK

System design and instrument development for future formation-flying magnetospheric satellite mission SCOPE

NASA Astrophysics Data System (ADS)

Saito, Y.; Fujimoto, M.; Maezawa, K.; Kojima, H.; Takashima, T.; Matsuoka, A.; Shinohara, I.; Tsuda, Y.; Higuchi, K.; Toda, T.

Japan Aerospace Exploration Agency JAXA is currently planning a next generation magnetosphere observation mission called SCOPE cross-Scale COupling in the Plasma universE The main purpose of this mission is to investigate the dynamic behaviors of plasmas in the Terrestrial magnetosphere that range over various time and spatial scales The basic idea of the SCOPE mission is to distinguish temporal and spatial variations of physical processes by putting five formation flying spacecraft into the key region of the Terrestrial magnetosphere The orbit of SCOPE is a highly elliptical orbit with its apogee 30Re from the Earth center SCOPE consists of one 450kg mother satellite and four 90kg daughter satellites flying 5 to 5000km apart from each other The inter-satellite link is used for telemetry command operation as well as ranging to determine the relative orbit of 5 satellites in a small distance which cannot be resolved by the ground-based orbit determination The SCOPE mission is designed such that observational studies from the new perspective that is the cross-scale coupling viewpoint are enabled The orbit is so designed that the spacecraft will visit most of the key regions in the magnetosphere that is the bow shock the magnetospheric boundary the inner-magnetosphere and the near-Earth magnetotail In order to realize the science objectives high performance Plasma Particle sensors DC AC Magnetic and Electric field sensors and Wave Particle Correlator are planned to be onboard the SCOPE satellite All the SCOPE satellites have two 5m spin-axis antenna

Imaging Magnetospheric Boundries at Ionospheric Heights

NASA Astrophysics Data System (ADS)

Baumgardner, J.; Nottingham, D.; Wroten, J.; Mendillo, M.

2001-12-01

Stable auroral red (SAR) arcs are excited by a downward heat flux within a narrow range of fluxtubes that define the plasmapause-ring current interaction region. Ambient F-region electrons near and above the peak height (300-500 km) are heated and collisionally excite atomic oxygen to the O(1D) state, thereby emitting 6300 A photons. At the same time, the diffuse aurora at 6300 A is excited by the precipitation of plasma sheet electrons into the lower thermosphere, exciting O(1D) to emit near 200 km. An all-sky imaging system operating at a sub-auroral site (e.g., at Millstone Hill) can readily record the SAR arc centroid location and the equatorial edge of the diffuse aurora in the same 6300 A image. We have analyzed 75 such cases showing where both stuctures occur in the ionosphere and then conducted field-line mapping to define the L-shell domains of origin in the equatorial plane of the inner magnetosphere (L ~ 2.5 - 4). To within the measurement and mapping accuracies, both boundaries coincide, i.e., the inner edge of the plasma sheet essentially falls along the plasmapause. Since the O(1D) 6300 A emission corresponds to ~2 ev of excitation by magnetospheric processes, this technique defines ELENA (Extremely Low Energetic Neutral Atom) imaging of magnetospheric structures.

Corotating Magnetic Reconnection Site in Saturn’s Magnetosphere

NASA Astrophysics Data System (ADS)

Yao, Z. H.; Coates, A. J.; Ray, L. C.; Rae, I. J.; Grodent, D.; Jones, G. H.; Dougherty, M. K.; Owen, C. J.; Guo, R. L.; Dunn, W. R.; Radioti, A.; Pu, Z. Y.; Lewis, G. R.; Waite, J. H.; Gérard, J.-C.

2017-09-01

Using measurements from the Cassini spacecraft in Saturn’s magnetosphere, we propose a 3D physical picture of a corotating reconnection site, which can only be driven by an internally generated source. Our results demonstrate that the corotating magnetic reconnection can drive an expansion of the current sheet in Saturn’s magnetosphere and, consequently, can produce Fermi acceleration of electrons. This reconnection site lasted for longer than one of Saturn’s rotation period. The long-lasting and corotating natures of the magnetic reconnection site at Saturn suggest fundamentally different roles of magnetic reconnection in driving magnetospheric dynamics (e.g., the auroral precipitation) from the Earth. Our corotating reconnection picture could also potentially shed light on the fast rotating magnetized plasma environments in the solar system and beyond.

Understanding Turbulence using Active and Passive Multipoint Measurements in Laboratory Magnetospheres

NASA Astrophysics Data System (ADS)

Mauel, M. E.; Abler, M. C.; Qian, T. M.; Saperstein, A.; Yan, J. R.

2017-10-01

In a laboratory magnetosphere, plasma is confined by a strong dipole magnet, and interchange and entropy mode turbulence can be studied and controlled in near steady-state conditions. Turbulence is dominated by long wavelength modes exhibiting chaotic dynamics, intermitency, and an inverse spectral cascade. Here, we summarize recent results: (i) high-resolution measurement of the frequency-wavenumber power spectrum using Capon's ``maximum likelihood method'', and (ii) direct measurement of the nonlinear coupling of interchange/entropy modes in a turbulent plasma through driven current injection at multiple locations and frequencies. These observations well-characterize plasma turbulence over a broad band of wavelengths and frequencies. Finally, we also discuss the application of these techniques to space-based experiments and observations aimed to reveal the nature of heliospheric and magnetospheric plasma turbulence. Supported by NSF-DOE Partnership in Plasma Science Grant DE-FG02-00ER54585.

A numerical code for a three-dimensional magnetospheric MHD equilibrium model

NASA Technical Reports Server (NTRS)

Voigt, G.-H.

1992-01-01

Two dimensional and three dimensional MHD equilibrium models were begun for Earth's magnetosphere. The original proposal was motivated by realizing that global, purely data based models of Earth's magnetosphere are inadequate for studying the underlying plasma physical principles according to which the magnetosphere evolves on the quasi-static convection time scale. Complex numerical grid generation schemes were established for a 3-D Poisson solver, and a robust Grad-Shafranov solver was coded for high beta MHD equilibria. Thus, the effects were calculated of both the magnetopause geometry and boundary conditions on the magnetotail current distribution.

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

The Source of Planetary Period Oscillations in Saturn's Magnetosphere

NASA Astrophysics Data System (ADS)

Khurana, Krishan K.; Mitchell, Jonathan L.; Mueller, Ingo C. F.

2017-04-01

In this presentation, we resolve a three-decades old mystery of how Saturn is able to modulate its kilometric wave radiation and many field and plasma parameters at the planetary rotation period even though its magnetic field is extremely axisymmetric. Such waves emanating from the auroral regions of planets lacking solid surfaces have been used as clocks to measure the lengths of their days, because asymmetric internal magnetic fields spin-modulate wave amplitudes. A review by Carbary and Mitchell (2013, Periodicities in Saturn's magnetosphere, Reviews of Geophysics, 51, 1-30) on the topic summarized findings from over 200 research articles, on what the phenomena is, how it is manifested in a host of magnetospheric and auroral parameters; examined several proposed models and pointed out their shortcomings. The topic has now been explored in several topical international workshops, but the problem has remained unsolved so far. By quantitatively modeling the amplitudes and phases of these oscillations in the magnetic field observed by the Cassini spacecraft, we have now uncovered the generation mechanism responsible for these oscillations. We show that the observed oscillations are the manifestations of two global convectional conveyor belts excited in Saturn's upper atmosphere by auroral heating below its northern and southern auroral belts. We demonstrate that a feedback process develops in Saturn system such that the magnetosphere expends energy to drive convection in Saturn's upper stratosphere but gains back an amplified share in the form of angular momentum that it uses to enforce corotation in the magnetosphere and power its aurorae and radio waves. In essence, we have uncovered a new mechanism (convection assisted loss of angular momentum in an atmosphere) by which gaseous planets lose their angular momentum to their magnetospheres and outflowing plasma at rates far above previous predictions. We next show how the m = 1 convection system in the upper

Jovian Substorms: A Study of Processes Leading to Transient Behavior in the Jovian Magnetosphere

NASA Technical Reports Server (NTRS)

Russell, C. T.

2000-01-01

Solar system magnetospheres can be divided into two groups: induced and intrinsic. The induced magnetospheres are produced in the solar wind interaction of the magnetized solar wind with planetary obstacles. Examples of these magnetospheres are those of comets, Venus and Mars. Intrinsic magnetospheres are the cavities formed in the solar wind by the magnetic fields produced by dynamo current systems inside the planets: Mercury, Earth, Jupiter, Saturn, Uranus and Neptune are known to have intrinsic magnetospheres. Intrinsic magnetospheres can be further subdivided as to how the circulating plasma is driven by external or internal processes. The magnetospheres of Mercury and Earth are driven by the solar wind. The magnetospheres of Jupiter and possibly of Saturn are principally driven by internal processes. These processes provide the energy for the powerful jovian radio signals that can be detected easily on the surface of the Earth.

Statistical Mapping of Bursty Bulk Flows in the Magnetosphere Supported by the Virtual Magnetospheric Observatory

NASA Astrophysics Data System (ADS)

Merka, J.; Sibeck, D. G.; Narock, T. W.

2011-12-01

Fast transient plasma flows in the magnetosphere are usually associated with magnetic reconnection and/or rapid changes in the magnetospheric configuration. Using a common methodology to analyze data from the THEMIS satellites we map the statistical occurrence rate of bursty bulk flows (BBFs) in the magnetosphere. Such a task involves obtaining and processing of large amount of data (5 THEMIS satellites provide measurements since spring of 2007), then writing custom code and searching for intervals of interests. The existence of a Virtual Magnetospheric Observatory (VMO) offers, however, a less laborious alternative. We discuss how the VMO made our research faster and easier and also point out the inherent limitations of the VMO use. The VMO's goal is to help researches by creating a single point of uniform discovery, access, and use of magnetospheric data. Available data can be searched based on various criteria as, for example, spatial location, time of observation, measurement type, parameter values, etc. The results can then be saved, downloaded or displayed as, for example, spatial-temporal plots that quickly reveal where and how often was the searched-for phenomenon observed. Our analysis revealed that the BBFs were found more frequently with increasing distance from Earth and the peak occurrence rate of earthward BBFs was at Xgsm = 29 Re and Ygsm = -2 Re. The tailward BBFs were very rarely observed even between Xgsm = -20 and -30 Re but they occurred over a wide range of local times. The positions with highest BBF occurrence rates differ from previous reports that used IRM and ISEE2 data.

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

Preliminary results on the plasma environment of saturn from the pioneer 11 plasma analyzer experiment.

PubMed

Wolfe, J H; Mihalov, J D; Collard, H R; McKibbin, D D; Frank, L A; Intriligator, D S

1980-01-25

The Ames Research Center Pioneer 11 plasma analyzer experiment provided measurements of the solar wind interaction with Saturn and the character of the plasma environment within Saturn's magnetosphere. It is shown that Saturn has a detached bow shock wave and magnetopause quite similar to those at Earth and Jupiter. The scale size of the interaction region for Saturn is roughly one-third that at Jupiter, but Saturn's magnetosphere is equally responsive to changes in the solar wind dynamic pressure. Saturn's outer magnetosphere is inflated, as evidenced by the observation of large fluxes of corotating plasma. It is postulated that Saturn's magnetosphere may undergo a large expansion when the solar wind pressure is greatly diminished by the presence of Jupiter's extended magnetospheric tail when the two planets are approximately aligned along the same solar radial vector.

SCOPE : Future Formation-Flying Magnetospheric Satellite Mission

NASA Astrophysics Data System (ADS)

Saito, Yoshifumi

A formation flight satellite mission "SCOPE" is now under study aiming at launching in 2017. "SCOPE" stands for ‘cross Scale COupling in the Plasma universE'. The main purpose of this mission is to investigate the dynamic behaviors of plasma in the terrestrial magnetosphere that range over magnitudes of both temporal and spatial scales. The basic idea of the SCOPE mission is to distinguish temporal and spatial variations of physical processes by putting five formation flight spacecraft into the key regions of the Earth's magnetosphere. The formation consists of one large mother satellite and four small daughter satellites. Three of the four daughter satellites surround the mother satellite 3-dimensionally maintaining the mutual distances of variable ranges between 5 km and 5000 km. The fourth daughter satellite stays near the mother satellite with the distance between 5 km and 100 km. By this configuration, we can obtain both the macro-scale (1000 km - 5000 km) and micro-scale (¡ 100 km) information about the plasma disturbances at the same time. The launcher for SCOPE has been assumed to be M-V rocket (or its succession rocket) of JAXA. However, due to the termination of M-V rocket, we are now considering to use HIIA. The orbits of SCOPE satellites are all highly elliptical with its apogee 30Re from the Earth center. The inter-satellite link is used for telemetry/command operation as well as ranging to determine the relative orbits of the 5 satellites in small distances. The SCOPE mission is designed such that observational studies from the new perspective, the crossscale coupling, should be conducted. The orbit of the formation flight are designed such that the spacecraft will visit most of the key regions in the magnetosphere, including the bow shock, the magnetospheric boundary, the inner-magnetosphere, and the near-Earth magnetotail. The key issues for the realization of this mission are: (1) The need for high temporal resolution of electron measurements

Global fully kinetic models of planetary magnetospheres with iPic3D

NASA Astrophysics Data System (ADS)

Gonzalez, D.; Sanna, L.; Amaya, J.; Zitz, A.; Lembege, B.; Markidis, S.; Schriver, D.; Walker, R. J.; Berchem, J.; Peng, I. B.; Travnicek, P. M.; Lapenta, G.

2016-12-01

We report on the latest developments of our approach to model planetary magnetospheres, mini magnetospheres and the Earth's magnetosphere with the fully kinetic, electromagnetic particle in cell code iPic3D. The code treats electrons and multiple species of ions as full kinetic particles. We review: 1) Why a fully kinetic model and in particular why kinetic electrons are needed for capturing some of the most important aspects of the physics processes of planetary magnetospheres. 2) Why the energy conserving implicit method (ECIM) in its newest implementation [1] is the right approach to reach this goal. We consider the different electron scales and study how the new IECIM can be tuned to resolve only the electron scales of interest while averaging over the unresolved scales preserving their contribution to the evolution. 3) How with modern computing planetary magnetospheres, mini magnetosphere and eventually Earth's magnetosphere can be modeled with fully kinetic electrons. The path from petascale to exascale for iPiC3D is outlined based on the DEEP-ER project [2], using dynamic allocation of different processor architectures (Xeon and Xeon Phi) and innovative I/O technologies.Specifically results from models of Mercury are presented and compared with MESSENGER observations and with previous hybrid (fluid electrons and kinetic ions) simulations. The plasma convection around the planets includes the development of hydrodynamic instabilities at the flanks, the presence of the collisionless shocks, the magnetosheath, the magnetopause, reconnection zones, the formation of the plasma sheet and the magnetotail, and the variation of ion/electron plasma flows when crossing these frontiers. Given the full kinetic nature of our approach we focus on detailed particle dynamics and distribution at locations that can be used for comparison with satellite data. [1] Lapenta, G. (2016). Exactly Energy Conserving Implicit Moment Particle in Cell Formulation. arXiv preprint ar

Ion Composition and Energization in the Earth's Inner Magnetosphere and the Effects on Ring Current Buildup

NASA Astrophysics Data System (ADS)

Keika, K.; Kistler, L. M.; Brandt, P. C.

2014-12-01

In-situ observations and modeling work have confirmed that singly-charged oxygen ions, O+, which are of Earth's ionospheric origin, are heated/accelerated up to >100 keV in the magnetosphere. The energetic O+ population makes a significant contribution to the plasma pressure in the Earth's inner magnetosphere during magnetic storms, although under quiet conditions H+ dominates the plasma pressure. The pressure enhancements, which we term energization, are caused by adiabatic heating through earthward transport of source population in the plasma sheet, local acceleration in the inner magnetosphere and near-Earth plasma sheet, and enhanced ion supply from the topside ionosphere. The key issues regarding stronger O+ energization than H+ are non-adiabatic local acceleration, responsible for increase in O+ temperature, and more significant O+ supply than H+, responsible for increase in O+ density. Although several acceleration mechanisms and O+ supply processes have been proposed, it remains an open question what mechanism(s)/process(es) play the dominant role in stronger O+ energization. In this paper we summarize important spacecraft observations including those from Van Allen Probes, introduces the proposed mechanisms/processes that generate O+-rich energetic plasma population, and outlines possible scenarios of O+ pressure abundance in the Earth's inner magnetosphere.

Energy-banded ions in Saturn's magnetosphere

NASA Astrophysics Data System (ADS)

Thomsen, M. F.; Badman, S. V.; Jackman, C. M.; Jia, X.; Kivelson, M. G.; Kurth, W. S.

2017-05-01

Using data from the Cassini Plasma Spectrometer ion mass spectrometer, we report the first observation of energy-banded ions at Saturn. Observed near midnight at relatively high magnetic latitudes, the banded ions are dominantly H+, and they occupy the range of energies typically associated with the thermal pickup distribution in the inner magnetosphere (L < 10), but their energies decline monotonically with increasing radial distance (or time or decreasing latitude). Their pitch angle distribution suggests a source at low (or slightly southern) latitudes. The band energies, including their pitch angle dependence, are consistent with a bounce-resonant interaction between thermal H+ ions and the standing wave structure of a field line resonance. There is additional evidence in the pitch angle dependence of the band energies that the particles in each band may have a common time of flight from their most recent interaction with the wave, which may have been at slightly southern latitudes. Thus, while the particles are basically bounce resonant, their energization may be dominated by their most recent encounter with the standing wave.