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Sample records for energetic particle instability

  1. Energetic particle instabilities in fusion plasmas

    NASA Astrophysics Data System (ADS)

    Sharapov, S. E.; Alper, B.; Berk, H. L.; Borba, D. N.; Breizman, B. N.; Challis, C. D.; Classen, I. G. J.; Edlund, E. M.; Eriksson, J.; Fasoli, A.; Fredrickson, E. D.; Fu, G. Y.; Garcia-Munoz, M.; Gassner, T.; Ghantous, K.; Goloborodko, V.; Gorelenkov, N. N.; Gryaznevich, M. P.; Hacquin, S.; Heidbrink, W. W.; Hellesen, C.; Kiptily, V. G.; Kramer, G. J.; Lauber, P.; Lilley, M. K.; Lisak, M.; Nabais, F.; Nazikian, R.; Nyqvist, R.; Osakabe, M.; Perez von Thun, C.; Pinches, S. D.; Podesta, M.; Porkolab, M.; Shinohara, K.; Schoepf, K.; Todo, Y.; Toi, K.; Van Zeeland, M. A.; Voitsekhovich, I.; White, R. B.; Yavorskij, V.; TG, ITPA EP; Contributors, JET-EFDA

    2013-10-01

    Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfvén instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomena. A multi-machine comparison is presented giving information on the performance of both diagnostics and modelling tools for different plasma conditions outlining expectations for ITER based on our present knowledge.

  2. Suppression of energetic particle driven instabilities with HHFW heating

    SciTech Connect

    Fredrickson, E. D.; Taylor, G.; Bertelli, N.; Darrow, D. S.; Gorelenkov, N.; Kramer, G.; Liu, D.; Crocker, N. A.; Kubota, S.; White, R.

    2015-01-01

    In plasmas in the National Spherical Torus Experiment (NSTX) [Ono et al., Nucl. Fusion 40 (2000) 557] heated with neutral beams, the beam ions typically excite Energetic Particle Modes (EPMs or fishbones), and Toroidal, Global or Compressional Alfvén Eigenmodes (TAE, GAE, CAE). These modes can redistribute the energetic beam ions, altering the beam driven current profile and the plasma heating profile, or they may affect electron thermal transport or cause losses of the beam ions. In this paper we present experimental results where these instabilities, driven by the super-thermal beam ions, are suppressed with the application of High Harmonic Fast Wave heating.

  3. Suppression of energetic particle driven instabilities with HHFW heating

    DOE PAGESBeta

    Fredrickson, E. D.; Taylor, G.; Bertelli, N.; Darrow, D. S.; Gorelenkov, N.; Kramer, G.; Liu, D.; Crocker, N. A.; Kubota, S.; White, R.

    2015-01-01

    In plasmas in the National Spherical Torus Experiment (NSTX) [Ono et al., Nucl. Fusion 40 (2000) 557] heated with neutral beams, the beam ions typically excite Energetic Particle Modes (EPMs or fishbones), and Toroidal, Global or Compressional Alfvén Eigenmodes (TAE, GAE, CAE). These modes can redistribute the energetic beam ions, altering the beam driven current profile and the plasma heating profile, or they may affect electron thermal transport or cause losses of the beam ions. In this paper we present experimental results where these instabilities, driven by the super-thermal beam ions, are suppressed with the application of High Harmonic Fastmore » Wave heating.« less

  4. Theory of resistive magnetohydrodynamic instabilities excited by energetic-trapped particles in large-size tokamaks

    SciTech Connect

    Biglari, H.; Chen, L.; White, R.B.

    1987-02-01

    It is shown that, in present-day large-size tokamaks, finite resistivity modifies qualitatively the stability properties of magnetohydrodynamic instabilities resonantly excited by the unfavorable processional drift of energetic-trapped particles, i.e., the so-called ''fishbone''-type instabilities. Specifically, it is found that (1) the n = 1 energetic-trapped particle-induced internal kink (''fishbone'') instability is strongly stabilized by resistive dissipation and (2) finite resistivity lowers considerably the threshold conditions for resonant excitations of high-n ballooning/interchange modes. The possibility of exciting fishbones by alpha particles in ignition experiments is also considered.

  5. Basic physics of Alfven instabilities driven by energetic particles in toroidally confined plasmas

    SciTech Connect

    Heidbrink, W. W.

    2008-05-15

    Superthermal energetic particles (EP) often drive shear Alfven waves unstable in magnetically confined plasmas. These instabilities constitute a fascinating nonlinear system where fluid and kinetic nonlinearities can appear on an equal footing. In addition to basic science, Alfven instabilities are of practical importance, as the expulsion of energetic particles can damage the walls of a confinement device. Because of rapid dispersion, shear Alfven waves that are part of the continuous spectrum are rarely destabilized. However, because the index of refraction is periodic in toroidally confined plasmas, gaps appear in the continuous spectrum. At spatial locations where the radial group velocity vanishes, weakly damped discrete modes appear in these gaps. These eigenmodes are of two types. One type is associated with frequency crossings of counterpropagating waves; the toroidal Alfven eigenmode is a prominent example. The second type is associated with an extremum of the continuous spectrum; the reversed shear Alfven eigenmode is an example of this type. In addition to these normal modes of the background plasma, when the energetic particle pressure is very large, energetic particle modes that adopt the frequency of the energetic particle population occur. Alfven instabilities of all three types occur in every toroidal magnetic confinement device with an intense energetic particle population. The energetic particles are most conveniently described by their constants of motion. Resonances occur between the orbital frequencies of the energetic particles and the wave phase velocity. If the wave resonance with the energetic particle population occurs where the gradient with respect to a constant of motion is inverted, the particles transfer energy to the wave, promoting instability. In a tokamak, the spatial gradient drive associated with inversion of the toroidal canonical angular momentum P{sub {zeta}} is most important. Once a mode is driven unstable, a wide variety

  6. Edge plasma responses to energetic-particle-driven MHD instability in Heliotron J

    NASA Astrophysics Data System (ADS)

    Ohshima, S.; Kobayashi, S.; Yamamoto, S.; Nagasaki, K.; Mizuuchi, T.; Okada, H.; Minami, T.; Hashimoto, K.; Shi, N.; Zang, L.; Kasajima, K.; Kenmochi, N.; Ohtani, Y.; Nagae, Y.; Mukai, K.; Lee, H. Y.; Matsuura, H.; Takeuchi, M.; Konoshima, S.; Sano, F.

    2016-01-01

    Two different responses to an energetic-particle-driven magnetohydrodynamic (MHD) instability, modulation of the turbulence amplitude associated with the MHD instability and dynamical changes in the radial electric field (Er) synchronized with bursting MHD activities, are found around the edge plasma in neutral beam injection (NBI) heated plasmas of the Heliotron J device using multiple Langmuir probes. The nonlinear phase relationship between the MHD activity and broadband fluctuation is found from bicoherence and envelope analysis applied to the probe signals. The structural changes of the Er profile appear in perfect synchronization with the periodic MHD activities, and radial transport of fast ions are observed around the last closed flux surface as a radial delay of the ion saturation current signals. Moreover, distortion of the MHD mode structure is clarified in each cycle of the MHD activities using beam emission spectroscopy diagnostics, suggesting that the fast ion distribution in real and/or velocity spaces is distorted in the core plasma, which can modify the radial electric field structure through a redistribution process of the fast ions. These observations suggest that such effects as a nonlinear coupling with turbulence and/or the modification of radial electric field profiles are important and should be incorporated into the study of energetic particle driven instabilities in burning plasma physics.

  7. Effect of Energetic Trapped Particles Produced by ICRF Wave Heating on Sawtooth Instability in the DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Choi, M.; Chan, V. S.; Chu, M. S.; Jeon, Y. M.; Lao, L. L.; Li, G.; Pinsker, R. I.; Ren, Q.; Turnbull, A. D.

    2007-09-01

    We evaluate the accuracy of the Porcelli sawtooth model using more realistic numerical models from the ORBIT-RF and GATO codes in DIII-D fast wave heating experiments. Simulation results confirm that the fast wave-induced energetic trapped particles may stabilize the sawtooth instability. The crucial kinetic stabilizing contribution strongly depends on both the experimentally reconstructed magnetic shear at the q = 1 surface and the calculated poloidal beta of energetic trapped particles inside the q = 1 surface.

  8. Global gyrokinetic models for energetic particle driven Alfvén instabilities in 3D equilibria

    NASA Astrophysics Data System (ADS)

    Spong, Don; Holod, Ihor

    2015-11-01

    The GTC global gyrokinetic PIC model has been adapted to 3D VMEC equilibria and provides a new method for the analysis of Alfvénic instabilities in stellarators, 3D tokamaks, and helical RFP states. The gyrokinetic orderings (k||/k⊥ << 1, ω/Ωci << 1, ρEP/L << 1) are applicable to a range of energetic particle driven instabilities that have been observed in 3D configurations. Applications of this model to stellarators have indicated that a variety of different Alfvén instabilities can be excited, depending on the toroidal mode number, fast ion average energy and fast ion density profile. Both an LHD discharge where bursting n = 1 Alfvén activity in the TAE gap was observed and a W7-X case have been examined. TAE,/EAE/GAE modes have been found in the simulations, depending on the mode family and fast ion profiles used. The dynamical evolution of the instabilities shows the field period coupling between n and n + Nfp expected for a stellarator. The development of gyrofluid reduced models that can capture relevant physics aspects of the gyrokinetic models will also be discussed. Research sponsored by the U.S. Department of Energy under Contract DE-AC05-00OR22725 with UT-Battelle, LLC and the GSEP SciDAC Center.

  9. One-dimensional energetic particle quasilinear diffusion for realistic TAE instabilities

    NASA Astrophysics Data System (ADS)

    Duarte, Vinicius; Ghantous, Katy; Berk, Herbert; Gorelenkov, Nikolai

    2014-10-01

    Owing to the proximity of the characteristic phase (Alfvén) velocity and typical energetic particle (EP) superthermal velocities, toroidicity-induced Alfvén eigenmodes (TAEs) can be resonantly destabilized endangering the plasma performance. Thus, it is of ultimate importance to understand the deleterious effects on the confinement resulting from fast ion driven instabilities expected in fusion-grade plasmas. We propose to study the interaction of EPs and TAEs using a line broadened quasilinear model, which captures the interaction in both regimes of isolated and overlapping modes. The resonance particles diffuse in the phase space where the problem essentially reduces to one dimension with constant kinetic energy and the diffusion mainly along the canonical toroidal angular momentum. Mode structure and wave particle resonances are computed by the NOVA code and are used in a quasilinear diffusion code that is being written to study the evolution of the distribution function, under the assumption that they can be considered virtually unalterable during the diffusion. A new scheme for the resonant particle diffusion is being proposed that builds on the 1-D nature of the diffusion from a single mode, which leads to a momentum conserving difference scheme even when there is mode overlap.

  10. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pinch

    SciTech Connect

    Lin, L.; Brower, D. L.; Ding, W. X.; Anderson, J. K.; Capecchi, W.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Nornberg, M. D.; Reusch, J.; Sarff, J. S.; Liu, D.

    2014-05-15

    Multiple bursty energetic-particle (EP) driven modes with fishbone-like structure are observed during 1 MW tangential neutral-beam injection in a reversed field pinch (RFP) device. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of EP instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport. Density fluctuations exhibit a dynamically evolving, inboard-outboard asymmetric spatial structure that peaks in the core where fast ions reside. The measured mode frequencies are close to the computed shear Alfvén frequency, a feature consistent with continuum modes destabilized by strong drive. The frequency pattern of the dominant mode depends on the fast-ion species. Multiple frequencies occur with deuterium fast ions compared to single frequency for hydrogen fast ions. Furthermore, as the safety factor (q) decreases, the toroidal mode number of the dominant EP mode transits from n=5 to n=6 while retaining the same poloidal mode number m=1. The transition occurs when the m=1, n=5 wave-particle resonance condition cannot be satisfied as the fast-ion safety factor (q{sub fi}) decreases. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growth phase arising from the beam fueling followed by a rapid drop when the EP modes peak, indicating that the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced with the onset of multiple EP modes.

  11. Global Hybrid Simulations of Energetic Particle Effects on the n=1 Mode in Tokamaks: Internal Kink and Fishbone Instability

    SciTech Connect

    G.Y. Fu; W. Park; H.R. Strauss; J. Breslau; J. Chen; S. Jardin; L.E. Sugiyama

    2005-08-09

    Global hybrid simulations of energetic particle effects on the n=1 internal kink mode have been carried out for tokamaks. For the International Thermonuclear Experimental Reactor (ITER) [ITER Physics Basis Editors et al., Nucl. Fusion 39:2137 (1999)], it is shown that alpha particle effects are stabilizing for the internal kink mode. However, the elongation of ITER reduces the stabilization effects significantly. Nonlinear simulations of the precessional drift fishbone instability for circular tokamak plasmas show that the mode saturates due to flattening of the particle distribution function near the resonance region. The mode frequency chirps down rapidly as the flattening region expands radially outward. Fluid nonlinearity reduces the saturation level.

  12. Nonlinear physics and energetic particle transport features of the beam-plasma instability

    NASA Astrophysics Data System (ADS)

    Carlevaro, Nakia; Falessi, Matteo V.; Montani, Giovanni; Zonca, Fulvio

    2015-10-01

    > In this paper we study transport features of a one-dimensional beam-plasma system in the presence of multiple resonances. As a model description of the general problem of a warm energetic particle beam, we assume cold supra-thermal beams and investigate the self-consistent evolution in the presence of the complete spectrum of nearly degenerate Langmuir modes. A qualitative transport estimation is obtained by computing the Lagrangian Coherent Structures of the system on given temporal scales. This leads to the splitting of the phase space into regions where the local transport processes are relatively faster. The general theoretical framework is applied to the case of the nonlinear dynamics of two cold beams, for which numerical simulation results are illustrated and analysed.

  13. The Energetics of Centrifugal Instability

    NASA Astrophysics Data System (ADS)

    Dewar, W. K.; Jiao, Y.

    2014-12-01

    A recent study has argued that the California Undercurrent, and poleward eastern boundary currents in general, generate mixing events through centrifugal instability (CI). Conditions favorable for CI are created by the strong horizontal shears developed in turbulent bottom layers of currents flowing in the direction of topographic waves. At points of abrupt topographic change, like promontories and capes, the coastal current separates from the boundary and injects gravitationally stable but dynamically unstable flow into the interior. The resulting finite amplitude development of the instability involves overturnings and diabatic mixing. The purpose of this study is to examine the energetics of CI in order to characterize it as has been done for other instabilities and develop a framework in which to estimate its regional and global impacts. We argue that CI is roughly twice as efficient at mixing as is Kelvin-Helmholtz instability, and that roughly 10% of the initial energy in a CUC-like current is lost to either local mixing or the generation of unbalanced flows. The latter probably leads to non-local mixing. Thus centrifugal instability is an effective process by which energy is lost from the balanced flow and spent in mixing neighboring water masses. We argue the importance of the mixing is regional in nature, but of less importance to the global budgets given its regional specificity.

  14. Onset condition of the subcritical geodesic acoustic mode instability in the presence of energetic-particle-driven geodesic acoustic mode

    NASA Astrophysics Data System (ADS)

    Itoh, K.; Itoh, S.-I.; Kosuga, Y.; Lesur, M.; Ido, T.

    2016-05-01

    An analytic model is developed for understanding the abrupt onset of geodesic acoustic mode (GAM) in the presence of chirping energetic-particle-driven GAM (EGAM). This abrupt excitation phenomenon has been observed on LHD plasma. Threshold conditions for the onset of abrupt growth of GAM are derived, and the period doubling phenomenon is explained. The phase relation between the mother mode (EGAM) and the daughter mode (GAM) is also discussed. This result contributes to the understanding of "trigger problems" of laboratory and nature plasmas.

  15. Energetic particles at Uranus

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  16. Solar Energetic Particle Variations

    NASA Technical Reports Server (NTRS)

    Reames, D. V.

    2003-01-01

    In the largest solar energetic-particle (SEP) events, acceleration occurs at shock waves driven out from the Sun by coronal mass ejections (CMEs). In fact, the highest proton intensities directly measured near Earth at energies up to approximately 1 GeV occur at the time of passage of shocks, which arrive about a day after the CMEs leave the Sun. CME-driven shocks expanding across magnetic fields can fill over half of the heliosphere with SEPs. Proton-generated Alfven waves trap particles near the shock for efficient acceleration but also throttle the intensities at Earth to the streaming limit early in the events. At high energies, particles begin to leak from the shock and the spectrum rolls downward to form an energy-spectral 'knee' that can vary in energy from approximately 1 MeV to approximately 1 GeV in different events. All of these factors affect the radiation dose as a function of depth and latitude in the Earth's atmosphere and the risk to astronauts and equipment in space. SEP ionization of the polar atmosphere produces nitrates that precipitate to become trapped in the polar ice. Observations of nitrate deposits in ice cores reveal individual large SEP events and extend back approximately 400 years. Unlike sunspots, SEP events follow the approximately 80-100-year Gleissberg cycle rather faithfully and are now at a minimum in that cycle. The largest SEP event in the last 400 years appears to be related to the flare observed by Carrington in 1859, but the probability of SEP events with such large fluences falls off sharply because of the streaming limit.

  17. Energetic particle physics with applications in fusion and space plasmas

    SciTech Connect

    Cheng, C.Z.

    1997-05-01

    Energetic particle physics is the study of the effects of energetic particles on collective electromagnetic (EM) instabilities and energetic particle transport in plasmas. Anomalously large energetic particle transport is often caused by low frequency MHD instabilities, which are driven by these energetic particles in the presence of a much denser background of thermal particles. The theory of collective energetic particle phenomena studies complex wave-particle interactions in which particle kinetic physics involving small spatial and fast temporal scales can strongly affect the MHD structure and long-time behavior of plasmas. The difficulty of modeling kinetic-MHD multiscale coupling processes stems from the disparate scales which are traditionally analyzed separately: the macroscale MHD phenomena are studied using the fluid MHD framework, while microscale kinetic phenomena are best described by complicated kinetic theories. The authors have developed a kinetic-MHD model that properly incorporates major particle kinetic effects into the MHD fluid description. For tokamak plasmas a nonvariational kinetic-MHD stability code, the NOVA-K code, has been successfully developed and applied to study problems such as the excitation of fishbone and Toroidal Alfven Eigenmodes (TAE) and the sawtooth stabilization by energetic ions in tokamaks. In space plasmas the authors have employed the kinetic-MHD model to study the energetic particle effects on the ballooning-mirror instability which explains the multisatellite observation of the stability and field-aligned structure of compressional Pc 5 waves in the magnetospheric ring current plasma.

  18. Solar Eruptions and Energetic Particles

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Natchimuthukonar; Mewaldt, Richard; Torsti, Jarmo

    Coronal mass ejections (CMEs) are the most energetic events in the heliosphere. During solar cycle 23, the close connection between CMEs and solar energetic particles (SEPs) was studied in much greater detail than was previously possible, including effects on space weather. This book reviews extensive observations of solar eruptions and SEPs from orbiting and ground-based systems. From SOHO and ACE to RHESSI and TRACE, we now have measurements of unprecedented sensitivity by which to test assumptions and refine models. Discussion and analysis of: • Coronal mass ejections and energetic particles over one solar cycle • Implications of solar eruptions for space weather and human space exploration • The elemental, isotopic, and ionic charge state composition of accelerated particles • Complex interconnections among CMEs, flares, shocks, and energetic particles will make this book an indispensable resource for scientists working on the Sun-Earth connection, including space physicists, magnetospheric physicists, atmospheric physicists, astrophysicists, and aeronomists.

  19. Solar flares and energetic particles.

    PubMed

    Vilmer, Nicole

    2012-07-13

    Solar flares are now observed at all wavelengths from γ-rays to decametre radio waves. They are commonly associated with efficient production of energetic particles at all energies. These particles play a major role in the active Sun because they contain a large amount of the energy released during flares. Energetic electrons and ions interact with the solar atmosphere and produce high-energy X-rays and γ-rays. Energetic particles can also escape to the corona and interplanetary medium, produce radio emissions (electrons) and may eventually reach the Earth's orbit. I shall review here the available information on energetic particles provided by X-ray/γ-ray observations, with particular emphasis on the results obtained recently by the mission Reuven Ramaty High-Energy Solar Spectroscopic Imager. I shall also illustrate how radio observations contribute to our understanding of the electron acceleration sites and to our knowledge on the origin and propagation of energetic particles in the interplanetary medium. I shall finally briefly review some recent progress in the theories of particle acceleration in solar flares and comment on the still challenging issue of connecting particle acceleration processes to the topology of the complex magnetic structures present in the corona. PMID:22665901

  20. EDITORIAL: Energetic particles in magnetic confinement systems

    NASA Astrophysics Data System (ADS)

    Toi, K.

    2006-10-01

    Energetic alpha particle physics plays an obviously crucial role in burning fusion plasmas. Good confinement of them is required to sustain fusion burn and to avoid damage of the first wall. Because of this importance for nuclear fusion research, Y. Kolesnichenko and the late D. Sigmar initiated a series of IAEA technical (committee) meetings (TCM, since the 8th meeting TM) in order to exchange information on the behaviour of energetic particles in magnetic confinement devices. The role of the TMs has become increasingly important since burning plasma projects such as ITER are in preparation. After every TM, invited speakers are encouraged to publish an adapted and extended version of their contributions to the meeting as an article in a special issue of Nuclear Fusion. An exception was the 8th TM the articles of which were published in a special issue of Plasma Physics and Controlled Fusion (2004 46 S1-118). These special issues attract much interest in the subject. The 9th IAEA TM of this series was held in Takayama, Japan, 9-11 November 2005, and 53 papers including 16 invited talks were presented. A total of 11 papers based on these invited talks are included in this special issue of Nuclear Fusion and are preceded by a conference summary. Experimental results of energetic ion driven global instabilities such as Alfvén eigenmodes (AEs), energetic particle modes (EPMs) and fishbone instabilities were presented from several tokamaks (JET, JT-60U, DIII-D and ASDEX Upgrade), helical/stellarator devices (LHD and CHS) and spherical tori (NSTX and MAST). Experimental studies from JET and T-10 tokamaks on the interaction of ion cyclotron waves with energetic ions and runaway electrons were also presented. Theoretical works on AEs, EPMs and nonlinear phenomena induced by energetic particles were presented and compared with experimental data. Extensive numerical codes have been developed and applied to obtain predictions of energetic particle behaviour in future ITER

  1. The Giotto Energetic Particle Experiment.

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Thompson, A.; O'Sullivan, D.; Kirsch, E.; Melrose, D.; Wenzel, K.-P.

    The Energetic Particle Experiment (EPA) onboard Giotto will measure the energy distribution of electrons, protons and heavier nuclei with E ≥ 20 keV during the cruise phase and in the cometary environment during Halley encounter. The detector system and the main scientific objectives of EPA are described.

  2. Energetic particle effects on global MHD modes

    SciTech Connect

    Cheng, C.Z.

    1990-01-01

    The effects of energetic particles on MHD type modes are studied by analytical theories and the nonvariational kinetic-MHD stability code (NOVA-K). In particular we address the problems of (1) the stabilization of ideal MHD internal kink modes and the excitation of resonant fishbone'' internal modes and (2) the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral-beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n=1 internal kink mode in the hot particle beat space exists even in the absence of core ion finite Larmor radius effect (finite {omega}{sub *i}). On the other hand, the trapped alpha particles are found to resonantly excite instability of the n=1 internal mode and can lower the critical beta threshold. The circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 23 refs., 5 figs.

  3. Virtual Energetic Particle Observatory (VEPO)

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Lal, Nand; McGuire, Robert E.; Szabo, Adam; Narock, Thomas W.; Armstrong, Thomas P.; Manweiler, Jerry W.; Patterson, J. Douglas; Hill, Matthew E.; Vandergriff, Jon D.; McKibben, Robert B.; Lopate, Clifford; Tranquille, Cecil

    2008-01-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events. acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  4. Virtual Energetic Particle Observatory (VEPO)

    NASA Astrophysics Data System (ADS)

    Cooper, J. F.; Lal, N.; McGuire, R. E.; Szabo, A.; Narock, T. W.; Armstrong, T. P.; Manweiler, J. W.; Patterson, J. D.; Hill, M. E.; Vandergriff, J. D.; McKibben, R. B.; Lopate, C.; Tranquille, C.

    2008-12-01

    The Virtual Energetic Particle Observatory (VEPO) focuses on improved discovery, access, and usability of heliospheric energetic particle and ancillary data products from selected spacecraft and sub-orbital instruments of the heliophysics data environment. The energy range of interest extends over the full range of particle acceleration from keV energies of suprathermal seed particles to GeV energies of galactic cosmic ray particles. Present spatial coverage is for operational and legacy spacecraft operating from the inner to the outer heliosphere, e.g. from measurements by the two Helios spacecraft to 0.3 AU to the inner heliosheath region now being traversed by the two Voyager spacecraft. This coverage will eventually be extended inward to ten solar radii by the planned NASA solar probe mission and at the same time beyond the heliopause into the outer heliosheath by continued Voyager operations. The geospace fleet of spacecraft providing near-Earth interplanetary measurements, selected magnetospheric spacecraft providing direct measurements of penetrating interplanetary energetic particles, and interplanetary cruise measurements from planetary spacecraft missions further extend VEPO resources to the domain of geospace and planetary interactions. Ground-based (e.g., neutron monitor) and high-altitude suborbital measurements can expand coverage to the highest energies of galactic cosmic rays affected by heliospheric interaction and of solar energetic particles. Science applications include investigation of solar flare and coronal mass ejection events, acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. Robotic and human exploration, and eventual habitation, of planetary and space environments beyond the Earth require knowledge of radiation

  5. Multiphase Instabilities in Explosive Dispersal of Particles

    NASA Astrophysics Data System (ADS)

    Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S. ``Bala''

    2015-11-01

    Explosive dispersal of particles is a complex multiphase phenomenon that can be observed in volcanic eruptions or in engineering applications such as multiphase explosives. As the layer of particles moves outward at high speed, it undergoes complex interactions with the blast-wave structure following the reaction of the energetic material. Particularly in this work, we are interested in the multiphase flow instabilities related to Richmyer-Meshkov (RM) and Rayleigh-Taylor (RM) instabilities (in the gas phase and particulate phase), which take place as the particle layer disperses. These types of instabilities are known to depend on initial conditions for a relatively long time of their evolution. Using a Eulerian-Lagrangian approach, we study the growth of these instabilities and their dependence on initial conditions related to the particulate phase - namely, (i) particle size, (ii) initial distribution, and (iii) mass ratio (particles to explosive). Additional complexities associated with compaction of the layer of particles are avoided here by limiting the simulations to modest initial volume fraction of particles. A detailed analysis of the initial conditions and its effects on multiphase RM/RT-like instabilities in the context of an explosive dispersal of particles is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

  6. Geodesic Acoustic Modes Induced by Energetic Particles

    NASA Astrophysics Data System (ADS)

    Zhou, Tianchun; Berk, Herbert

    2009-11-01

    A global geodesic acoustic mode driven by energetic particles (EGAM) has been observed in JET[1, 2] and DIII D[3, 4]. The mode is to be treated fully kinetically. The descriptions of the background electrons and ions are based on standard high and low bounce frequency expansion respectively with respect to the mode frequency. However, the energetic ions must be treated without any expansion of ratio between their bounce frequency and the mode frequency since they are comparable. Under electrostatic perturbation, we construct a quadratic form for the wave amplitude, from which an integro-differential equation is derived. In the limit where the drift orbit width is small comparison with the mode width, a differential equation for perturbed electrostatic field is obtained. Solution is obtained both analytically and numerically. We find that beam counterinjection enhances the instability of the mode. Landau damping due to thermal species is investigated.

  7. Geodesic Acoustic Modes Induced by Energetic Particles

    NASA Astrophysics Data System (ADS)

    Zhou, Tianchun; Berk, Herbert

    2009-05-01

    A global geodesic acoustic mode driven by energetic particles (EGAM) has been observed in JET[1, 2] and DIII D[3, 4]. The mode is to be treated fully kinetically. The descriptions of the background electrons and ions are based on standard high and low bounce frequency expansion respectively with respect to the mode frequency. However, the energetic ions must be treated without any expansion of ratio between their bounce frequency and the mode frequency since they are comparable. Under electrostatic perturbation, we construct a quadratic form for the wave amplitude, from which an integro-differential equation is derived. In the limit where the drift orbit width is small comparison with the mode width, a differential equation for perturbed electrostatic field is obtained. Solution is obtained both analytically and numerically. We find that beam counterinjection enhances the instability of the mode

  8. The Giotto energetic particle experiment

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Thompson, A.; Sullivan, D.; Kirsch, E.; Melrose, D.; Wenzel, K. P.

    1986-03-01

    The Energetic Particle Experiment (EPA) onboard Giotto will measure the energy distribution of electrons, protons, and heavier nuclei (E is greater than 20 keV) during the cruise phase and in the cometary environment during the Halley encounter. The detector system consists of three particle telescopes each incorporating totally depleted silicon surface barrier layer detectors, and employing active and passive background shielding. In-situ measurements will be made of the flux and spatial distribution of energetic electrons and cometary ions in the Halley environment. Particle acceleration due to magnetic-field-line reconnection processes will, if present, be detected. The occurrence of a solar-particle event during the encounter would provide special opportunities to study the comet/solar-wind interaction and dust distribution around the comet, while the EPA would act as a reference for onboard instruments that are sensitive to particle radiation. Cruise-phase studies provide interplanetary particle flux levels since switch-on, and flare-related particle enhancements are detected.

  9. Solar Energetic Particle Spectrometer (SEPS)

    NASA Technical Reports Server (NTRS)

    Christl, Mark J.

    2009-01-01

    An outstanding problem of solar and heliospheric physics is the transport of solar energetic particles. The more energetic particles arriving early in the event can be used to probe the transport processes. The arrival direction distribution of these particles carries information about scattering during their propagation to Earth that can be used to test models of interplanetary transport. Also, of considerable importance to crewed space missions is the level of ionizing radiation in the interplanetary medium, and the dose that the crew experiences during an intense solar particle event, as well as the risk to space systems. A recent study concludes that 90% of the absorbed dose results from particles in the energy range 20-550 MeV. We will describe a new compact instrument concept, SEPS, that can cover the energy range from 50-600 MeV with a single compact detector. This energy range has been difficult to cover. There are only limited data, generally available only in broad energy bins, from a few past and present instruments outside Earth s magnetosphere. The SEPS concept can provide improved measurements for this energy range and its simple light-weight design could be easily accommodated on future missions.

  10. Extreme solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Vainio, Rami; Afanasiev, Alexandr; Battarbee, Markus

    2016-04-01

    Properties of extreme solar energetic particle (SEP) events, here defined as those leading to ground level enhancements (GLEs) of cosmic rays, are reviewed. We review recent efforts on modeling SEP acceleration to relativistic energies and present simulation results on particle acceleration at shocks driven by fast coronal mass ejections (CMEs) in different types of coronal magnetic structures and turbulent downstream compression regions. Based on these modeling results, we discuss the possible role of solar and CME parameters in the lack of GLEs during the present sunspot cycle. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA). The Academy of Finland is thanked for financial support.

  11. The Energetic Assessment of Frictional Instability Based on Rowe's Theory

    NASA Astrophysics Data System (ADS)

    Hirata, M.; Muto, J.; Nagahama, H.

    2015-12-01

    Frictional instability that controls the occurrence of unstable slips has been related to (1) rate and state dependent friction law (Dieterich, 1979; Ruina, 1983) and (2) shear localization in a gouge layer (e.g., Byerlee et al., 1978; Logan et al., 1979). Ikari et al. (2011) indicated that the transitions of frictional parameters obtained from the rate and state dependent friction law involve shear localization. However, the underlining theoretical background for their link has been unknown. Therefore, in this study, we investigate their relation theoretically and experimentally based on Rowe's theory on constant minimum energy ratio (Rowe, 1962) describing particle deformations quantitatively by energetic analysis. In theoretical analysis using analytical dynamics and irreversible thermodynamics, the energetic criterion about frictional instability is obtained; unstable slip occurs at energy ratios below 1. In friction experiments using a gas medium apparatus, simulated fault gouge deforms obeying the Rowe's theory. Additionally, the energy ratios change gradually with shear and show below 1 before the occurrence of unstable slip. Moreover, energy ratios are derived from volume changes. Transition of energy ratios from increase to decrease, which has been confirmed at the end of compaction, indicates the onset of volume increase toward the occurrence of unstable slip. The volume increases likely correspond to the formation of R1-shears with open mode character, which occurs prior to the unstable slip. Shear localization leads to a change in internal friction angle which is a statistical parameter to constitute a energy ratio. In short, changes in internal friction angle play an important role in evolving from being frictionally stable to unstable. From these results, the physical and energetic background for their link between the frictional parameter and shear localization becomes clear.

  12. Quasilinear Model for Energetic Particles Interacting with TAE Modes

    NASA Astrophysics Data System (ADS)

    Ghantous, Katy; Gorelenkov, Nikolai; Berk, Herbert

    2010-11-01

    TAE instabilities are thought to be a major source of Energetic Particle transport which could set limits on operational scenarios, especially for burning plasmas, and causes damage to the first wall. The quasilinear model proposed by Berk et al.ootnotetextH. L. Berk et al, Nucl. Fusion, 35:1661, 1995. relies on diffusion mechanisms for particle dynamics to captures the evolution of the energetic particle distribution function and the associated mode amplitude. Using the bump-on-tail as a paradigm, we analyze the dynamics near the resonances for accurate diffusion coefficient representation. We verify the model to get the predicted single mode saturation levels and benchmark the case of multimode overlap against particle codes. Using the TAE mode structures computed by the ideal MHD code NOVA, we generalize this method to relax energetic particles' profiles in the full 3D phase space.

  13. The Galileo Energetic Particles Detector

    NASA Technical Reports Server (NTRS)

    Williams, D. J.; Mcentire, R. W.; Jaskulek, S.; Wilken, B.

    1992-01-01

    Amongst its complement of particles and fields instruments, the Galileo spacecraft carries an Energetic Particles Detector (EPD) designed to measure the characteristics of particle populations important in determining the size, shape, and dynamics of the Jovian magnetosphere. To do this the EPD provides 4pi angular coverage and spectral measurements for Z greater than or equal to 1 ions from 20 keV to 55 MeV, for electrons from 15 keV to greater than 11 MeV, and for the elemental species helium through iron from approximately 10 keV/nucl to 15 MeV/nucl. Two bidirectional telescopes, mounted on a stepping platform, employ magnetic deflection, energy loss versus energy, and time-of-flight techniques to provide 64 rate channels and pulse height analysis of priority selected events. The EPD data system provides a large number of possible operational modes from which a small number will be selected to optimize data collection during the many encounter and cruise phases of the mission. The EPD employs a number of safeing algorithms that are to be used in the event that its self-checking procedures indicate a problem. The instrument and its operation are described.

  14. Energetic particle influences in Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Aplin, Karen; Harrison, R. Giles; Nicoll, Keri; Rycroft, Michael; Briggs, Aaron

    2016-04-01

    Energetic particles from outer space, known as galactic cosmic rays, constantly ionise the entire atmosphere. During strong solar storms, solar energetic particles can also reach the troposphere and enhance ionisation. Atmospheric ionisation generates cluster ions. These facilitate current flow in the global electric circuit, which arises from charge separation in thunderstorms driven by meteorological processes. Energetic particles, whether solar or galactic in origin, may influence the troposphere and stratosphere through a range of different mechanisms, each probably contributing a small amount. Some of the suggested processes potentially acting over a wide spatial area in the troposphere include enhanced scavenging of charged aerosol particles, modification of droplet or droplet-droplet behavior by charging, and the direct absorption of infra-red radiation by the bending and stretching of hydrogen bonds inside atmospheric cluster-ions. As well as reviewing the proposed mechanisms by which energetic particles modulate atmospheric properties, we will also discuss new instrumentation for measurement of energetic particles in the atmosphere.

  15. Observations and Modeling of Geospace Energetic Particles

    NASA Astrophysics Data System (ADS)

    Li, Xinlin

    2016-07-01

    Comprehensive measurements of energetic particles and electric and magnetic fields from state-of-art instruments onboard Van Allen Probes, in a geo-transfer-like orbit, revealed new features of the energetic particles and the fields in the inner magnetosphere and impose new challenges to any quantitative modeling of the physical processes responsible for these observations. Concurrent measurements of energetic particles by satellites in highly inclined low Earth orbits and plasma and fields by satellites in farther distances in the magnetospheres and in the up stream solar wind are the critically needed information for quantitative modeling and for leading to eventual accurate forecast of the variations of the energetic particles in the magnetosphere. In this presentation, emphasis will be on the most recent advance in our understanding of the energetic particles in the magnetosphere and the missing links for significantly advance in our modeling and forecasting capabilities.

  16. Energetic Particle-induced Geodesic Acoustic Mode

    SciTech Connect

    Fu, G.Y.

    2008-09-12

    A new energetic particle-induced Geodesic Acoustic Mode (EGAM) is shown to exist. The mode frequency, mode structure, and mode destabilization are determined non-perturbatively by energetic particle kinetic effects. In particular the EGAM frequency is found to be substantially lower than the standard GAM frequency. The radial mode width is determined by the energetic particle drift orbit width and can be fairly large for high energetic particle pressure and large safety factor. These results are consistent with the recent experimental observation of the beam- driven n=0 mode in DIII-D. The new mode is important since it can degrade energetic particle confinement as shown in the DIII-D experiments. The new mode may also affect the thermal plasma confinement via its interaction with plasma micro-turbulence.

  17. Energetic Particle Influence on the Earth's Atmosphere

    NASA Astrophysics Data System (ADS)

    Mironova, Irina A.; Aplin, Karen L.; Arnold, Frank; Bazilevskaya, Galina A.; Harrison, R. Giles; Krivolutsky, Alexei A.; Nicoll, Keri A.; Rozanov, Eugene V.; Turunen, Esa; Usoskin, Ilya G.

    2015-11-01

    This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth's atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere.

  18. Subsatellite measurements of plasma and energetic particles

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.; Chase, L. M.; Lin, R. P.; Mccoy, J. E.; Mcguire, R. E.

    1972-01-01

    The Apollo 16 particles and fields subsatellite is instrumented to measure (1) plasma and energetic-particle fluxes, (2) vector magnetic fields, and (3) velocity of the subsatellite to a high precision for the purpose of determining lunar gravitational anomalies. Results from the magnetic-field and gravitational-field experiments are discussed. The results obtained from the plasma and energetic-particle detectors are discussed briefly. The plasma and energetic-particles experiment describes the various plasma regimes in which the moon moves, and determines how the moon interacts with the plasma and magnetic fields in the environment.

  19. Marginal Stability Dynamics for Energetic Particles

    NASA Astrophysics Data System (ADS)

    Berk, Herbert

    2009-11-01

    Marginal stability in plasmas characteristically sets a stiff limit to the range of that can be achieved. Below this limit, the system is governed by classical. Near marginal stability, however, plasmas may be subject to rapid processes, resulting in a system that hovers near marginality. This scenario emerged from nonlinear studies of energetic particle relaxation and may be to more general plasma transport. We describe results from several such which include. [1] Avalanches---Near marginal stability, an important point is whether an instability driven by resonant particles where the distribution function has ``free energy'' will cause global radial diffusion. For that,modes need to overlap. This process can be continuous or bursty, the latter having been recently observed in NSTX and DIII-D. [2] Frequency chirping---Recent simulations by Vann showed that marginal stability can be sustained when there is only one unstable linear mode, due to the mechanism of spontaneous frequency sweeping. Although a single mode near stability should not cause dramatic relaxation, nevertheless in the Vann simulations, the achievement of marginal stability induced a continual chirping of that had removed energy from the bulk of the region where the external beam to deposit free energy. The distribution was then found to hover near stability. This mechanism may apply to the n=0 GAM where frequency sweeping might be a mechanism for extracting energy from alpha particles in a burning plasma, thereby reducing the stored alpha particle pressure. One way to implement this is to have the n=0 geodesic acoustic modes (GAM) be preferentially excited, since energy rather than momentum (leading to spatial diffusion) is then primarily extracted from alpha particles.

  20. Nuclear gamma rays from energetic particle interactions

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Kozlovsky, B.; Lingenfelter, R. E.

    1978-01-01

    Gamma ray line emission from nuclear deexcitation following energetic particle reactions is evaluated. The compiled nuclear data and the calculated gamma ray spectra and intensities can be used for the study of astrophysical sites which contain large fluxes of energetic protons and nuclei. A detailed evaluation of gamma ray line production in the interstellar medium is made.

  1. Size distributions of solar energetic particle events

    NASA Technical Reports Server (NTRS)

    Cliver, E.; Reames, D.; Kahler, S.; Cane, H.

    1991-01-01

    NASA particle detectors on the IMP-8 are employed to determine the size distributions of the peak fluxes of events related to solar-energetic particles including protons and electrons. The energetic proton events show a flatter size distribution which suggests that not all flares are proton flares. Both the electron and proton events are classified as either 'impulsive' or 'gradual', and the impulsive events tend to have a steeper power-law distribution.

  2. Fast excitation of geodesic acoustic mode by energetic particle beams

    SciTech Connect

    Cao, Jintao; Qiu, Zhiyong; Zonca, Fulvio

    2015-12-15

    A new mechanism for geodesic acoustic mode (GAM) excitation by a not fully slowed down energetic particle (EP) beam is analyzed to explain experimental observations in Large Helical Device. It is shown that the positive velocity space gradient near the lower-energy end of the EP distribution function can strongly drive the GAM unstable. The new features of this EP-induced GAM (EGAM) are: (1) no instability threshold in the pitch angle; (2) the EGAM frequency can be higher than the local GAM frequency; and (3) the instability growth rate is much larger than that driven by a fully slowed down EP beam.

  3. Migrational Instabilities in Particle Suspensions

    NASA Technical Reports Server (NTRS)

    Goddard, Joe D.

    1996-01-01

    This work deals with an instability arising from the shear-induced migration of particles in dense suspensions coupled with a dependence of viscosity on particle concentration. The analysis summarized here treats the inertialess (Re = O) linear stability of homogeneous simple shear flows for a Stokesian suspension model of the type proposed by Leighton and Acrivos (1987). Depending on the importance of shear-induced migration relative to concentration-driven diffusion, this model admits short-wave instability arising from wave-vector stretching by the base flow and evolving into particle-depleted shear bands. Moreover, this instability in the time-dependent problem corresponds to loss of ellipticity in the associated static problem (Re = O, Pe = O). While the isotropic version of the Leighton-Acrivos model is found to be stable with their experimentally determined parameters for simple shear, it is known that the stable model does not give a good quantitative description of particle clustering in the core of pipe flow (Nott and Brady 1994). This leads to the conjecture that an appropriate variant on the above model could explain such clustering as a two-phase bifurcation in the base flow.

  4. The MAVEN Solar Energetic Particle Investigation

    NASA Astrophysics Data System (ADS)

    Larson, Davin E.; Lillis, Robert J.; Lee, Christina O.; Dunn, Patrick A.; Hatch, Kenneth; Robinson, Miles; Glaser, David; Chen, Jianxin; Curtis, David; Tiu, Christopher; Lin, Robert P.; Luhmann, Janet G.; Jakosky, Bruce M.

    2015-12-01

    The MAVEN Solar Energetic Particle (SEP) instrument is designed to measure the energetic charged particle input to the Martian atmosphere. SEP consists of two sensors mounted on corners of the spacecraft deck, each utilizing a dual, double-ended solid-state detector telescope architecture to separately measure fluxes of electrons from 20 to 1000 keV and ions from 20-6000 keV, in four orthogonal look directions, each with a field of view of 42° by 31°. SEP, along with the rest of the MAVEN instrument suite, allows the effects of high energy solar particle events on Mars' upper atmospheric structure, temperatures, dynamics and atmospheric escape rates, to be quantified and understood. Given that solar activity was likely substantially higher in the early solar system, understanding the relationship between energetic particle input and atmospheric loss today will enable more confident estimates of total atmospheric loss over Mars' history.

  5. Isomon instabilities driven by energetic ions in Wendelstein 7-X

    NASA Astrophysics Data System (ADS)

    Kolesnichenko, Ya. I.; Könies, A.; Lutsenko, V. V.; Drevlak, M.; Turkin, Yu.; Helander, P.

    2016-06-01

    It is found that modes of Alfvénic character affected by plasma compressibility and having equal poloidal and toroidal mode numbers (named ‘isomon modes’) can exist in W7-X. These modes, and the conditions under which they arise, are sensitive to the magnitude of the rotational transform of the field lines and the presence of energetic ions. The energetic ions produced by neutral-beam injection (having the energy 55–60 keV) interact resonantly with large-scale isomon modes (m=n\\ll 10 ), which tends to lead to instabilities extending over a large part of the plasma cross section.

  6. Numerical Analyses of Energetic Particles in LHD

    SciTech Connect

    Todo, Yasushi; Murakami, S.; Yamamoto, T.; Fukuyama, A.; Spong, Donald A; Yamamoto, S.; Osakabe, M.; Nakajima, N.

    2010-01-01

    The confinement of energetic ions generated by neutral beam injection (NBI) and ion cyclotron resonance frequency heating is studied using GNET simulation code, in which the drift kinetic equation is solved in five-dimensional phase-space. The steady-state distributions of the energetic ions are obtained, and characteristics of the energetic-ion distribution depending on the plasma heating method are shown. The magnetic configuration effect on the energetic-ion confinement is also investigated, and it is found that the energetic-ion confinement is improved by a strong inward shift of the magnetic axis position in the major radius direction. The interaction between energetic particles and Alfven eigenmodes are investigated using the MEGA code and the AE3D code. A reduced version of the MEGA code has been developed to simulate the Alfven eigenmode (AE) evolution in the Large Helical Device (LHD) plasma with NBI and collisions taken into account. The spatial profile and frequency of the AE modes in the LHD plasma are analyzed with the AE3D code. The evolution of energetic particles and AE mode amplitude and phase are followed in a self-consistent way, while the AE spatial profiles are assumed to be constant. It is demonstrated that the AE bursts can be simulated with the new code.

  7. Energetic particle pressure in intense ESP events

    NASA Astrophysics Data System (ADS)

    Lario, D.; Decker, R. B.; Roelof, E. C.; Viñas, A.-F.

    2015-09-01

    We study three intense energetic storm particle (ESP) events in which the energetic particle pressure PEP exceeded both the pressure of the background thermal plasma Pth and the pressure of the magnetic field PB. The region upstream of the interplanetary shocks associated with these events was characterized by a depression of the magnetic field strength coincident with the increase of the energetic particle intensities and, when plasma measurements were available, a depleted solar wind density. The general feature of cosmic-ray mediated shocks such as the deceleration of the upstream background medium into which the shock propagates is generally observed. However, for those shocks where plasma parameters are available, pressure balance is not maintained either upstream of or across the shock, which may result from the fact that PEP is not included in the calculation of the shock parameters.

  8. Energetic solar particle behaviour in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Scholer, M.

    1979-01-01

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

  9. Physics of Alfvén waves and energetic particles in burning plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Liu; Zonca, Fulvio

    2016-01-01

    Dynamics of shear Alfvén waves and energetic particles are crucial to the performance of burning fusion plasmas. This article reviews linear as well as nonlinear physics of shear Alfvén waves and their self-consistent interaction with energetic particles in tokamak fusion devices. More specifically, the review on the linear physics deals with wave spectral properties and collective excitations by energetic particles via wave-particle resonances. The nonlinear physics deals with nonlinear wave-wave interactions as well as nonlinear wave-energetic particle interactions. Both linear as well as nonlinear physics demonstrate the qualitatively important roles played by realistic equilibrium nonuniformities, magnetic field geometries, and the specific radial mode structures in determining the instability evolution, saturation, and, ultimately, energetic-particle transport. These topics are presented within a single unified theoretical framework, where experimental observations and numerical simulation results are referred to elucidate concepts and physics processes.

  10. Energetic Particles Dynamics in Mercury's Magnetosphere

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  11. SIMULATION OF ENERGETIC NEUTRAL ATOMS FROM SOLAR ENERGETIC PARTICLES

    SciTech Connect

    Wang, Linghua; Li, Gang; Shih, Albert Y.; Lin, Robert P.; Wimmer-Schweingruber, Robert F.

    2014-10-01

    Energetic neutral atoms (ENAs) provide the only way to observe the acceleration site of coronal-mass-ejection-driven (CME-driven) shock-accelerated solar energetic particles (SEPs). In gradual SEP events, energetic protons can charge exchange with the ambient solar wind or interstellar neutrals to become ENAs. Assuming a CME-driven shock with a constant speed of 1800 km s{sup –1} and compression ratio of 3.5, propagating from 1.5 to 40 R{sub S} , we calculate the accelerated SEPs at 5-5000 keV and the resulting ENAs via various charge-exchange interactions. Taking into account the ENA losses in the interplanetary medium, we obtain the flux-time profiles of these solar ENAs reaching 1 AU. We find that the arriving ENAs at energies above ∼100 keV show a sharply peaked flux-time profile, mainly originating from the shock source below 5 R{sub S} , whereas the ENAs below ∼20 keV have a flat-top time profile, mostly originating from the source beyond 10 R{sub S} . Assuming the accelerated protons are effectively trapped downstream of the shock, we can reproduce the STEREO ENA fluence observations at ∼2-5 MeV/nucleon. We also estimate the flux of ENAs coming from the charge exchange of energetic storm protons, accelerated by the fast CME-driven shock near 1 AU, with interstellar hydrogen and helium. Our results suggest that appropriate instrumentation would be able to detect ENAs from SEPs and to even make ENA images of SEPs at energies above ∼10-20 keV.

  12. Composition of energetic particles from solar flares

    NASA Technical Reports Server (NTRS)

    Garrard, T. L.; Stone, E. C.

    1994-01-01

    We present a model for composition of heavy ions in the Solar Energetic Particles (SEP). The SEP composition in a typical large solar particle event reflects the composition of the Sun, with adjustments due to fractionation effects which depend on the First Ionization Potential (FIP) of the ion and on the ratio of ionic charge to mass (Q/M). Flare-to flare variations in composition are represented by parameters describing these fractionation effects and the distributions of these parameters are presented.

  13. Excitation of external kink mode by trapped energetic particles

    NASA Astrophysics Data System (ADS)

    Guo, S. C.; Xu, X. Y.; Liu, Y. Q.; Wang, Z. R.

    2016-05-01

    An unstable fishbone-like non-resonant external kink mode (FLEM) is numerically found to be driven by the precessional drift motion of trapped energetic particles (EPs) in both reversed-field pinch (RFP) and tokamak plasmas, even under the ideal wall boundary condition. In the presence of a sufficiently large fraction of trapped energetic ions in high beta plasmas, the FLEM instability may occur. The excitation condition is discussed in detail. The frequency of the FLEM is linked to the precessional drift frequency of EPs, and varies with the plasma flow speed. Therefore, it is usually much higher than that of the typical resistive wall mode (RWM). In general, the growth rate of FLEM does not depend on the wall resistivity. However, the wall position can significantly affect the mode’s property. The drift kinetic effects from thermal particles (mainly due to the transit resonance of passing particles) play a stabilizing role on FLEMs. In the presence of EPs, the FLEM and the RWM can co-exist or even couple to each other, depending on the plasma parameters. The FLEM instabilities in RFP and tokamaks have rather similar physics nature, although certain sub-dominant characters appear differently in the two configurations.

  14. Access of energetic particles to Titan's exobase

    NASA Astrophysics Data System (ADS)

    Regoli, L.; Roussos, E.; Feyerabend, M.; Jones, G.; Krupp, N.; Coates, A.; Simon, S.; Motschmann, U.

    2015-10-01

    In this contribution we use a particle tracing code to trace energetic particles close to Titan in the specific magnetospheric conditions of the Cassini T9 flyby. The particles simulated are H+and O+ions with energies ranging from 1 keV to 1 MeV and the background electromagnetic field is represented by the output of the A.I.K.E.F. hybrid code for that specific flyby. These tools are used to generate 2D maps showing the access of the particles to the moon's exobase and those maps are subsequently used to normalize the fluxes measured by the Cassini MIMI/CHEMS instrument and estimate the energy deposition at specific positions around the moon.With this, we are able to estimate the importance that the asymmetries in the access of particles to the exobase has in the dynamics of Titan's ionosphere.

  15. Ring current instabilities excited by the energetic oxygen ions

    SciTech Connect

    Kakad, A. P.; Singh, S. V.; Lakhina, G. S.

    2007-09-15

    The ring current instabilities driven by the energetic oxygen ions are investigated during the magnetic storm. The electrons and protons are considered to have Maxwellian distributions, while energetic oxygen ions are having loss-cone distribution. Dispersion relation for the quasielectrostatic modes with frequencies {omega}>{omega}{sub cp} (proton cyclotron frequency) and propagating obliquely to the magnetic field is obtained. Dispersion relation is studied numerically for the storm time ring current parameters and it is found that these instabilities are most prominent during intense storms when the oxygen ions become the dominant constituents of the ring current plasma. For some typical storm-time ring current parameters, these modes can produce quasielectrostatic noise in the range of 17-220 Hz, thus providing a possible explanation of the electrostatic noise observed at the inner boundary of the ring current during magnetic storms. Further, these modes can attain saturation electric fields of the order of 100-500 {mu}V/m, and therefore, are expected to scatter O{sup +} ions into the loss-cone giving rise to their precipitation into the atmosphere, thus contributing to the ring current decay.

  16. Solar Energetic Particle Studies with PAMELA

    NASA Technical Reports Server (NTRS)

    Bravar, U.; Christian, E. R.; deNolfo, Georgia; Ryan, J. M.; Stochaj, S.

    2011-01-01

    The origin of the high-energy solar energetic particles (SEPs) may conceivably be found in composition signatures that reflect the elemental abundances of the low corona and chromosphere vs. the high corona and solar wind. The presence of secondaries, such as neutrons and positrons, could indicate a low coronal origin of these particles. Velocity dispersion of different species and over a wide energy range can be used to determine energetic particle release times at the Sun. Together with multi-wavelength imaging, in- situ observations of a variety of species, and coverage over a wide energy range provide a critical tool in identifying the origin of SEPs, understanding the evolution of these events within the context of solar active regions, and constraining the acceleration mechanisms at play. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA)instrument, successfully launched in 2006 and expected to remain operational until at least the beginning of 2012, measures energetic particles in the same energy range as ground-based neutron monitors, and lower energies as well. It thus bridges the gap between low energy in-situ observations and ground-based Ground Level Enhancements (GLE) observations. It can measure the charge (up to Z=6) and atomic number of the detected particles, and it can identify and measure positrons and detect neutrons-an unprecedented array of data channels that we can bring to bear on the origin of high-energy SEPs. We present prelimiary results on the for the 2006 December 13 solar flare and GLE and the 2011 March 21 solar flare, both registering proton and helium enhancements in PAMELA. Together with multi- spacecraft contextual data and modeling, we discuss the PAMELA results in the context of the different acceleration mechanisms at play.

  17. Solar energetic particle transport in the heliosphere

    NASA Astrophysics Data System (ADS)

    Pei, Chunsheng

    2007-08-01

    The transport of solar energetic particles (SEPs) in the inner heliosphere is a very important issue which can affect our daily life. For example, large SEP events can lead to the failure of power grids, interrupt communications, and may participate in global climate change. The SEPS also can harm humans in space and destroy the instruments on board spacecraft. Studying the transport of SEPs also helps us understand remote regions of space which are not visible to us because there are not enough photons in those places. The interplanetary magnetic field is the medium in which solar energetic particles travel. The Parker Model of the solar wind and its successor, the Weber and Davis model, have been the dominant models of the solar wind and the interplanetary magnetic field since 1960s. In this thesis, I have reviewed these models and applied an important correction to the Weber and Davis model Various solar wind models and their limitations are presented. Different models can affect the calculation of magnetic field direction at 1 AU by as much as about 30%. Analysis of the onset of SEP events could be used to infer the release time of solar energetic particles and to differentiate between models of particle acceleration near the Sun. It is demonstrated that because of the nature of the stochastic heliospheric magnetic field, the path length measured along the line of force can be shorter than that of the nominal Parker spiral. These results help to explain recent observations. A two dimensional model and a fully three dimensional numerical model for the transport of SEPs has been developed based on Parker's transport equation for the first time. ''Reservoir'' phenomenon, which means the inner heliosphere works like a reservoir for SEPs during large SEP events, and multi-spacecraft observation of peak intensities are explained by this numerical model.

  18. Dose spectra from energetic particles and neutrons

    NASA Astrophysics Data System (ADS)

    Schwadron, Nathan; Bancroft, Chris; Bloser, Peter; Legere, Jason; Ryan, James; Smith, Sonya; Spence, Harlan; Mazur, Joe; Zeitlin, Cary

    2013-10-01

    spectra from energetic particles and neutrons (DoSEN) are an early-stage space technology research project that combines two advanced complementary radiation detection concepts with fundamental advantages over traditional dosimetry. DoSEN measures not only the energy but also the charge distribution (including neutrons) of energetic particles that affect human (and robotic) health in a way not presently possible with current dosimeters. For heavy ions and protons, DoSEN provides a direct measurement of the lineal energy transfer (LET) spectra behind shielding material. For LET measurements, DoSEN contains stacks of thin-thick Si detectors similar in design to those used for the Cosmic Ray Telescope for the Effects of Radiation. With LET spectra, we can now directly break down the observed spectrum of radiation into its constituent heavy-ion components and through biologically based quality factors that provide not only doses and dose rates but also dose equivalents, associated rates, and even organ doses. DoSEN also measures neutrons from 10 to 100 MeV, which requires enough sensitive mass to fully absorb recoil particles that the neutrons produce. DoSEN develops the new concept of combining these independent measurements and using the coincidence of LET measurements and neutron detection to significantly reduce backgrounds in each measurement. The background suppression through the use of coincidence allows for significant reductions in size, mass, and power needed to provide measurements of dose, neutron dose, dose equivalents, LET spectra, and organ doses. Thus, we introduce the DoSEN concept: a promising low-mass instrument that detects the full spectrum of energetic particles, heavy ions, and neutrons to determine biological impact of radiation in space.

  19. Coronal abundances determined from energetic particles

    NASA Technical Reports Server (NTRS)

    Reames, D. V.

    1995-01-01

    Solar energetic particles (SEPs) provide a measurement of coronal element abundances that is highly independent of the ionization states and temperature of the ions in the source plasma. The most complete measurements come from large 'gradual' events where ambient coronal plasma is swept up by the expanding shock wave from a coronal mass ejection. Particles from 'impulsive' flares have a pattern of acceleration-induced enhancements superimposed on the coronal abundances. Particles accelerated from high-speed solar wind streams at corotating shocks show a different abundance pattern corresponding to material from coronal holes. Large variations in He/O in coronal material are seen for both gradual and impulsive-flare events but other abundance ratios, such as Mg/Ne, are remarkably constant. SEP measurements now include hundreds of events spanning 15 years of high-quality measurement.

  20. ENERGETIC PARTICLE ANISOTROPIES AT THE HELIOSPHERIC BOUNDARY

    SciTech Connect

    Florinski, V.; Le Roux, J. A.; Jokipii, J. R.; Alouani-Bibi, F.

    2013-10-20

    In 2012 August the Voyager 1 space probe entered a distinctly new region of space characterized by a virtual absence of heliospheric energetic ions and magnetic fluctuations, now interpreted as a part of the local interstellar cloud. Prior to their disappearance, the ion distributions strongly peaked at a 90° pitch angle, implying rapid escape of streaming particles along the magnetic field lines. Here we investigate the process of particle crossing from the heliosheath into the interstellar space, using a kinetic approach that resolves scales of the particle's cyclotron radius and smaller. It is demonstrated that a 'pancake' pitch-angle distribution naturally arises at a tangential discontinuity separating a weakly turbulent plasma from a laminar region with a very low pitch-angle scattering rate. The relatively long persistence of gyrating ions is interpreted in terms of field line meandering facilitating their cross-field diffusion within the depletion region.

  1. SAMPEX: New Insights into Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Klecker, B.

    2012-12-01

    One of the scientific objectives of SAMPEX (Solar, Anomalous, Magnetospheric Particle EXplorer) was the study of solar energetic particles (SEPs). The low altitude high inclination (82°) orbit of SAMPEX was selected in part to measure SEPs and interplanetary particles (e.g. related to corotating interaction regions) over the polar caps, and to provide the unique capability of determining their charge states, utilizing the rigidity dependent cutoff of the magnetic field of the Earth. The four instruments onboard SAMPEX were novel ion and electron detectors with unprecedented sensitivity, with geometric factors of up to 100 cm2 sr, providing measurements of solar and interplanetary particles with elemental and isotopic resolution over a wide energy range (~0.3 to 70 MeV/nuc for Fe). The high sensitivity of the SAMPEX instrumentation combined with using Earth's magnetic field as a M/Q spectrometer provided the first (and so far only) direct SEP ionic charge measurements at energies up to 10s of MeV/nuc. These measurements showed for the first time evidence of an energy dependence of the mean charge of solar energetic particles, suggesting multiple sources in large SEP events and ion stripping in the low corona. The high sensitivity of the SAMPEX instruments also allowed the measurement of energy spectra over a wide energy range, showing characteristic differences in spectral breaks in large SEP events, and systematic enrichment of heavy isotopes in 3He-rich events. Furthermore, the high time resolution SEP measurements from the polar cap to low latitudes provided an ideal tool to study dynamic variations of the Earth's large scale magnetic field, by measuring cutoff variations during large SEP events. This talk will give an overview of the contributions of SAMPEX to our present understanding of SEPs and also summarize related SAMPEX highlights.

  2. Solar Energetic Particles: Sampling Coronal Abundances

    NASA Astrophysics Data System (ADS)

    Reames, Donald V.

    1998-05-01

    In the large solar energetic particle (SEP) events, coronal mass ejections (CMEs) drive shock waves out through the corona that accelerate elements of the ambient material to MeV energies in a fairly democratic, temperature-independent manner. These events provide the most complete source of information on element abundances in the corona. Relative abundances of 22 elements from H through Zn display the well-known dependence on the first ionization potential (FIP) that distinguishes coronal and photospheric material. For most elements, the main abundance variations depend upon the gyrofrequency, and hence on the charge-to-mass ratio, Q/A, of the ion. Abundance variations in the dominant species, H and He, are not Q/A dependent, presumably because of non-linear wave-particle interactions of H and He during acceleration. Impulsive flares provide a different sample of material that confirms the Ne:Mg:Si and He/C abundances in the corona.

  3. Solar Energetic Particle Events Observed by MAVEN

    NASA Astrophysics Data System (ADS)

    Lee, C. O.; Larson, D. E.; Lillis, R. J.; Luhmann, J. G.; Halekas, J. S.; Brain, D.; Connerney, J. E. P.; Espley, J. R.; Epavier, F.; Thiemann, E.; Zeitlin, C.; Jakosky, B. M.

    2015-12-01

    We present observations of solar energetic particle (SEP) events made by the Mars Atmosphere and Volatile EvolutioN (MAVEN) SEP instrument, which measures energetic ions and electrons impacting the upper Martian atmosphere. Since the arrival of the MAVEN spacecraft at Mars, a large number of solar flares and a few major coronal mass ejections (CMEs) erupted from the Sun. The SEPs are accelerated by the related shock in the solar corona or by the propagating interplanetary shock ahead of the CME ejecta. Mixed in with these SEPs are particles accelerated by the shocks of corotating streams, some of which have recurred for several solar cycles due to the persistent coronal hole sources. The SEP events are analyzed together with the upstream solar wind observations from the MAVEN Solar Wind Ion Analyzer (SWIA) and magnetometer (MAG). The sources of the SEP events are determined from Earth-based solar imagery and the MAVEN Extreme Ultra-violet Monitor (EUVM) together with numerical simulations of the inner heliospheric conditions. A comparison with the radiation dose rate measurements from the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD) reveals a lack of ground signatures during the onset of the highest energy SEPs for the events observed by MAVEN, indicating that the SEPs fully deposit their energies into the Martian atmosphere. Using measurements made from the ensemble of instruments onboard MAVEN, we investigate the consequences of SEPs at Mars for a number of events observed during the primary science mapping phase of the MAVEN mission.

  4. Baseline composition of solar energetic particles

    SciTech Connect

    Meyer, J.

    1985-01-01

    We analyze all existing spacecraft observations of the highly variable heavy element composition of solar energetic particles (SEP) during non-/sup 3/He-rich events. All data show the imprint of an ever-present basic composition pattern (dubbed ''mass-unbiased baseline'' SEP composition) that differs from the photospheric composition by a simple bias related to first ionization potential (FIP). In each particular observation, this mass-unbiased baseline composition is being distorted by an additional bias, which is always a monotonic function of mass (or Z). This latter bias varies in amplitude and even sign from observation to observation. To first order, it seems related to differences in the A/Z* ratio between elements (Z* = mean effective charge).

  5. STEREO Observations of Solar Energetic Particles

    NASA Technical Reports Server (NTRS)

    vonRosenvinge, Tycho; Christian, Eric; Cohen, Christina; Leske, Richard; Mewaldt, Richard; Stone, Edward; Wiedenbeck, Mark

    2011-01-01

    We report on observations of Solar Energetic Particle (SEP) events as observed by instruments on the STEREO Ahead and Behind spacecraft and on the ACE spacecraft. We will show observations of an electron event observed by the STEREO Ahead spacecraft on June 12, 2010 located at W74 essentially simultaneously with electrons seen at STEREO Behind at E70. Some similar events observed by Helios were ascribed to fast electron propagation in longitude close to the sun. We will look for independent verification of this possibility. We will also show observations of what appears to be a single proton event with very similar time-history profiles at both of the STEREO spacecraft at a similar wide separation. This is unexpected. We will attempt to understand all of these events in terms of corresponding CME and radio burst observations.

  6. Energetic particles in the jovian magnetotail.

    PubMed

    McNutt, R L; Haggerty, D K; Hill, M E; Krimigis, S M; Livi, S; Ho, G C; Gurnee, R S; Mauk, B H; Mitchell, D G; Roelof, E C; McComas, D J; Bagenal, F; Elliott, H A; Brown, L E; Kusterer, M; Vandegriff, J; Stern, S A; Weaver, H A; Spencer, J R; Moore, J M

    2007-10-12

    When the solar wind hits Jupiter's magnetic field, it creates a long magnetotail trailing behind the planet that channels material out of the Jupiter system. The New Horizons spacecraft traversed the length of the jovian magnetotail to >2500 jovian radii (RJ; 1 RJ identical with 71,400 kilometers), observing a high-temperature, multispecies population of energetic particles. Velocity dispersions, anisotropies, and compositional variation seen in the deep-tail (greater, similar 500 RJ) with a approximately 3-day periodicity are similar to variations seen closer to Jupiter in Galileo data. The signatures suggest plasma streaming away from the planet and injection sites in the near-tail region (approximately 200 to 400 RJ) that could be related to magnetic reconnection events. The tail structure remains coherent at least until it reaches the magnetosheath at 1655 RJ. PMID:17932283

  7. Solar Energetic Particles Trapping in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Engel, M.; Larsen, B. A.

    2011-12-01

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

  8. CUSP Energetic Particles: Confinement, Acceleration and Implications

    NASA Technical Reports Server (NTRS)

    Chen, Jiasheng

    1999-01-01

    The cusp energetic particle (CEP) event is a new magnetospheric phenomenon. The events were detected in the dayside cusp for hours, in which the measured helium ions had energies up to 8 MeV. All of these events were associated with a dramatic decrease and large fluctuations in the local magnetic field strength. During January 1999 - December 1999 covered by this report, I have studied the CEP events by analyzing the POLAR, GEOTAIL, and WIND particle and magnetic field data measured during the geomagnetic quiet periods in 1996 and one geomagnetic storm period in 1998. The simultaneous observations indicated that the ion fluxes in the CEP events were higher than that in both the upstream and the downstream from the bow shock. The pitch angle distribution of the helium ions in the CEP events was found to peak around 90 deg. It was found that the mirror parameter, defined as the ratio of the square root of the integration of the parallel turbulent power spectral component over the ultra-low frequency (ULF) ranges to the mean field in the cusp, is correlated with the intensity of the cusp MeV helium flux, which is a measure of the influence of mirroring interactions and an indication of local effect. It was also found that the turbulent power of the local magnetic field in the ultra-low frequency (ULF) ranges is correlated with the intensity of the cusp energetic helium ions. Such ULF ranges correspond to periods of about 0.33-500 seconds that cover the gyroperiods, the bounce periods, and the drift periods of the tens keV to MeV charged particles when they are temporarily confined in the high-altitude dayside cusp. These observations represent a discovery that the high-altitude dayside cusp is a new acceleration and dynamic trapping region of the magnetosphere. The cusp geometry is connected via gradient and curvature drift of these energized ions to the equatorial plasma sheet as close as the geostationary orbit at local midnight. It implies that the dayside cusp is

  9. Solar Energetic Particles and Space Weather

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.; Tylka, Allan J.; Ng, Chee K.

    2001-01-01

    The solar energetic particles (SEPs) of consequence to space weather are accelerated at shock waves driven out from the Sun by fast coronal mass ejections (CMEs). In the large events, these great shocks fill half of the heliosphere. SEP intensity profiles change appearance with longitude. Events with significant intensities of greater than ten MeV protons occur at an average rate of approx. 13 per year near solar maximum and several events with high intensities of > 100 McV protons occur each decade. As particles stream out along magnetic field lines from a shock near the Sun, they generate waves that scatter subsequent particles. At high intensities, wave growth throttles the flow below the 'streaming limit.' However, if the shock maintains its strength, particle intensities can rise above this limit to a peak when the shock itself passes over the observer creating a 'delayed' radiation hazard, even for protons with energies up to approx. one GeV. The streaming limit makes us blind to the intensities at the oncoming shock, however, heavier elements such as He, O, and Fe probe the shape of the wave spectrum, and variation in abundances of these elements allow us to evade the limit and probe conditions at the shock, with the aid of detailed modeling. At high energies, spectra steepen to form a spectral 'knee'. The location of the proton spectral knee can vary from approx. ten MeV to approx. one GeV, depending on shock conditions, greatly affecting the radiation hazard. Hard spectra are a serious threat to astronauts, placing challenging requirements for shielding, especially on long-duration missions to the moon or Mars.

  10. Energetic Particle Observations Near the Termination Shock

    SciTech Connect

    Krimigis, Stamatios M.; Decker, Robert B.; Roelof, Edmond C.; Hill, Matthew E.

    2004-09-15

    The most recent data from Voyager 1 (V1) show that a second event (TS2), apparently associated with the termination shock (TS), is in progress, with spectral characteristics similar to the energetic particle increase observed from 2002.4-2003.1 (TS1). We concentrate on the pressure, composition, and anisotropy profiles of TS1. The magnetic field pressure is significantly smaller than the particle pressure perpendicular to the interplanetary magnetic field (IMF) in the 40-4000 keV range. The composition during the interplanetary shock event (ISE) observed by V1 during 1991 is drastically different from that during TS1 (C/O {approx}0.2 for ISE, {approx}0.02 for TS1). The dominant anisotropy during TS1 is azimuthally in the outward direction for a Parker spiral field, suggesting a source inward of the spacecraft, while the radial anisotropy is consistent with zero (-0.024 {+-} 0.02), implying a slow (<50 km/s) plasma flow speed. We conclude that the totality of the data is consistent with V1 being in the heliosheath during TS1.

  11. Kinetic transport simulation of energetic particles

    NASA Astrophysics Data System (ADS)

    Sheng, He; Waltz, R. E.

    2016-05-01

    A kinetic transport code (EPtran) is developed for the transport of the energetic particles (EPs). The EPtran code evolves the EP distribution function in radius, energy, and pitch angle phase space (r, E, λ) to steady state with classical slowing down, pitch angle scattering, as well as radial and energy transport of the injected EPs (neutral beam injection (NBI) or fusion alpha). The EPtran code is illustrated by treating the transport of NBI fast ions from high-n ITG/TEM micro-turbulence and EP driven unstable low-n Alfvén eigenmodes (AEs) in a well-studied DIII-D NBI heated discharge with significant AE central core loss. The kinetic transport code results for this discharge are compared with previous study using a simple EP density moment transport code ALPHA (R.E. Waltz and E.M. Bass 2014 Nucl. Fusion 54 104006). The dominant EP-AE transport is treated with a local stiff critical EP density (or equivalent pressure) gradient radial transport model modified to include energy-dependence and the nonlocal effects EP drift orbits. All previous EP transport models assume that the EP velocity space distribution function is not significantly distorted from the classical ‘no transport’ slowing down distribution. Important transport distortions away from the slowing down EP spectrum are illustrated by a focus on the coefficient of convection: EP energy flux divided by the product of EP average energy and EP particle flux.

  12. PLASMA ENERGETIC PARTICLES SIMULATION CENTER (PEPSC)

    SciTech Connect

    Berk, Herbert L.

    2014-05-23

    The main effort of the Texas group was to develop theoretical and simplified numerical models to understand chirping phenomena often seen for Alfven and geodesic acoustic waves in experimental plasmas such as D-III-D, NSTX and JET. Its main numerical effort was to modify the AEGIS code, which was originally developed as an eigenvalue solver. To apply to the chirping problem this code has to be able to treat the linear response to the continuum and the response of the plasma to external drive or to an internal drive that comes from the formation of phase space chirping structures. The theoretical underpinning of this investigation still needed to be more fully developed to understand how to best formulate the theoretical problem. Considerable progress was made on this front by B.N. Breizman and his collaborators and a new reduced model was developed by H. L. Berk and his PhD student, G. Wang which can be uses as simplified model to describe chirping in a large aspect ratio tokamak. This final report will concentrate on these two directions that were developed as well as results that were found in the work with the AEGIS code and in the progress in developing a novel quasi-linear formulation for a description of Alfvenic modes destabilized by energetic particles, such as alpha particles in a burning plasma.

  13. The energy spectra of solar energetic particles

    NASA Technical Reports Server (NTRS)

    Mcguire, R. E.; Von Rosenvinge, T. T.

    1984-01-01

    A survey of recent results on the shapes and relative slopes of the spectra of various solar energetic particle populations is presented, with emphasis on the more extensive results currently available for protons, alphas and electrons. From previous work, it is found that proton spectra 0.8 to more than 400 MeV and alpha spectra 1.4 to 80 MeV/nucleon are best characterized, on average, by a functional form involving a Bessel function in momentum/nucleon. However, proton and alpha spectral slopes using this form are not equal, and there is significant variation from event to event. From other studies, electrons 0.02 to 20 MeV are also found to have curved spectra, but seem to be better fit with a double power law in energy. The spectral properties in both cases correlate with other measures of solar particle acceleration; e.g. gamma-ray line production, hard X-ray burst spectra and microwave fluxes.

  14. Effect of dynamical friction on nonlinear energetic particle modes

    SciTech Connect

    Lilley, M. K.; Breizman, B. N.; Sharapov, S. E.

    2010-09-15

    A fully nonlinear model is developed for the bump-on-tail instability including the effects of dynamical friction (drag) and velocity space diffusion on the energetic particles driving the wave. The results show that drag provides a destabilizing effect on the nonlinear evolution of waves. Specifically, in the early nonlinear phase of the instability, the drag facilitates the explosive scenario of the wave evolution, leading to the creation of phase space holes and clumps that move away from the original eigenfrequency. Later in time, the electric field associated with a hole is found to be enhanced by the drag, whereas for a clump it is reduced. This leads to an asymmetry of the frequency evolution between holes and clumps. The combined effect of drag and diffusion produces a diverse range of nonlinear behaviors including hooked frequency chirping, undulating, and steady state regimes. An analytical model is presented, which explains the aforementioned diversity. A continuous production of hole-clump pairs in the absence of collisions is also observed.

  15. Rocket measurements of energetic particles in the midlatitude precipitation zone

    NASA Technical Reports Server (NTRS)

    Voss, H. D.; Smith, L. G.; Braswell, F. M.

    1980-01-01

    Measurements of energetic ion and electron properties as a function of altitude in the midlatitude zone of nighttime energetic particle precipitation are reported. The measurements of particle fluxes, energy spectra and pitch angle distributions were obtained by a Langmuir probe, six energetic particle spectrometers and an electrostatic analyzer on board a Nike Apache rocket launched near the center of the midlatitude zone during disturbed conditions. It is found that the incident flux was primarily absorbed rather than backscattered, and consists of mainly energetic hydrogen together with some helium and a small energetic electron component. Observed differential energy spectra of protons having an exponential energy spectrum, and pitch angle distributions at various altitudes indicate that the energetic particle flux decreases rapidly for pitch angles less than 70 deg. An energetic particle energy flux of 0.002 ergs/sq cm per sec is calculated which indicates the significance of energetic particles as a primary nighttime ionization source for altitudes between 120 and 200 km in the midlatitude precipitation zone.

  16. Intensity Variation of Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2011-01-01

    This paper updates the influence of environmental and source factors of shocks driven by corona) mass ejections (CMEs) that are likely to influence the intensity of solar energetic particle (SEP) events. The intensity variation due to CME interaction reported in Gopalswamy et al. (2004, JGR 109, Al2105) is confirmed by expanding the investigation to all the large SEP events of solar cycle 23. The large SEP events are separated into two groups, one associated with CMEs running into other CMEs, and the other with CMEs running into the ambient solar wind. SEP events with CME interaction generally have a higher intensity. New possibilities such as the influence of corona) holes on the SEP intensity are also discussed. For example, the presence of a large coronal hole between a well-connected eruption and the solar disk center may render the shock poorly connected because of the interaction between the CME and the coronal hole. This point is illustrated using the 2004 December 3 SEP event delayed by about 12 hours from the onset of the associated CME. There is no other event at the Sun that can be associated with the SEP onset. This event is consistent with the possibility that the coronal hole interaction influences the connectivity of the CMEs that produce SEPs, and hence the intensity of the SEP event.

  17. Elemental composition of solar energetic particles

    NASA Technical Reports Server (NTRS)

    Cook, W. R.; Stone, E. C.; Vogt, R. E.

    1984-01-01

    The Low Energy Telescopes on the Voyager spacecraft have been used to measure the elemental composition (Z = 2-28) and energy spectra (5-15 MeV per nucleon) of solar energetic particles (SEPs) in seven large flare events. Four flare events were selected which have SEP abundance ratios approximately independent of energy per nucleon. For these selected flare events, SEP composition results may be described by an average composition plus a systematic flare-to-flare deviation about the average. The four-flare average SEP composition is systematically different from the solar composition determined by photospheric spectroscopy. These systematic composition differences are apparently not due to SEP propagation or acceleration effects. In contrast, the four-flare average SEP composition is in agreement with measured solar wind abundances and with a number of recent spectroscopic coronal abundance measurements. These findings suggest that SEPs originate in the corona, and that both SEPs and the solar wind sample a coronal composition which is significantly and persistently different from that measured for the photosphere.

  18. Energetic Particles Events inside Magnetic Clouds

    NASA Astrophysics Data System (ADS)

    Medina, Jose; Hidalgo, Miguel Angel; Blanco, Juan Jose; Rodriguez-Pacheco, Javier

    The effect of the magnetic topology of the Magnetic Clouds (MCs) over the energetic particle event (EPe) fluxes (0.5-100 MeV) have been simulated. In the data corresponding to the ion and electron fluxes, a depression after a strong maximum is observed when a EPe passes through a MC. Using our cross-section circular and elliptical MC models (Journal of Geophysical Research 107(1), doi:10.1029/2001JA900100 (2002) and Solar Physics 207(1), 187-198 (2002)) we have tried to explain that effect, understanding the importance of the topology of the MC. In sight of the results of the preliminary analysis we conclude that the magnitude of the magnetic field seems not to play a significant role but the helicoidal topology associated with topology of the MCs. This work has been supported by the Spanish Comisín Internacional de o Ciencia y Tecnoloǵ (CICYT), grant ESP2005-07290-C02-01 and ESP2006-08459. This work ıa is performed inside COST Action 724.

  19. Energetic particle abundances in solar electron events

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Cane, H. V.; Von Rosenvinge, T. T.

    1990-01-01

    The results of a comprehensive search of the ISEE 3 energetic particle data for solar electron events with associated increases in elements with atomic number Z = 6 or greater are reported. A sample of 90 such events was obtained. The events support earlier evidence of a bimodal distribution in Fe/O or, more clearly, in Fe/C. Most of the electron events belong to the group that is Fe-rich in comparison with the coronal abundance. The Fe-rich events are frequently also He-3-rich and are associated with type III and type V radio bursts and impulsive solar flares. Fe-poor events are associated with type IV bursts and with interplanetary shocks. With some exceptions, event-to-event enhancements in the heavier elements vary smoothly with Z and with Fe/C. In fact, these variations extend across the full range of events despite inferred differences in acceleration mechanism. The origin of source material in all events appears to be coronal and not photospheric.

  20. Temporal Evolution of Solar Energetic Particle Spectra

    NASA Astrophysics Data System (ADS)

    Doran, Donald J.; Dalla, Silvia

    2016-08-01

    During solar flares and coronal mass ejections, Solar Energetic Particles (SEPs) may be released into the interplanetary medium and near-Earth locations. The energy spectra of SEP events at 1 AU are typically averaged over the entire event or studied in a few snapshots. In this article we analyze the time evolution of the energy spectra of four large selected SEP events using a large number of snapshots. We use a multi-spacecraft and multi-instrument approach for the observations, obtained over a wide SEP energy range. We find large differences in the spectra at the beginning of the events as measured by different instruments. We show that over time, a wave-like structure is observed traveling through the spectra from the highest energies to the lowest energies, creating an "arch" shape that then straightens into a power law later in the event, after times on the order of 10 hours. We discuss the processes that determine SEP intensities and their role in shaping the spectral time evolution.

  1. The Two Sources of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Reames, Donald V.

    2012-05-01

    The identification of two different physical mechanisms for acceleration of solar energetic particles (SEPs) began nearly 50 years ago with the radio observations of type III bursts produced by outward streaming electrons and type II bursts from coronal (and interplanetary) shock waves. Since that time we have found that the former are related to “impulsive” SEP events from flares or jets where resonant stochastic acceleration, probably related to magnetic reconnection, can produce 1000-fold enhancements of 3He/4He and of (Z>50)/O, for example, while the latter “gradual” SEP events sample ion abundances democratically and are used to measure the coronal abundances of the elements. Sometimes, unfortunately, residual impulsive suprathermal ions can also contribute to the seed population for shock acceleration, complicating the picture, but this process can now be modeled theoretically. Initially, impulsive events behave like a point source on the Sun, while multi-spacecraft observations of gradual events show extensive acceleration that can span half of the inner heliosphere, beginning when the shock reaches 2 solar radii. Acceleration occurs as ions are scattered back and forth across the shock by proton-generated resonant Alfven waves. These waves also define a streaming-limited maximum intensity or plateau region prior to arrival of the shock. Behind the shock lies an extensive “reservoir” region of spatially uniform SEP intensity that decreases with time as the “magnetic bottle” enclosing it expands.

  2. Energetic Particles in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

    Malandraki, Olga

    2016-07-01

    Solar Energetic Particle (SEP) events are a key ingredient of Solar-Terrestrial Physics both for fundamental research and space weather applications. SEP events are the defining component of solar radiation storms, contribute to radio blackouts in polar regions and are related to many of the fastest Coronal Mass Ejections (CMEs) driving major geomagnetic storms. In addition to CMEs, SEPs are also related to flares. In this work, the current state of knowledge on the SEP field will be reviewed. Key issues to be covered and discussed include: the current understanding of the origin, acceleration and transport processes of SEPs at the Sun and in the inner heliosphere, lessons learned from multi-spacecraft SEP observations, statistical quantification of the comparison of solar events and SEP events of the current solar cycle 24 with previous solar cycles, causes of the solar-cycle variations in SEP fluencies and composition, theoretical work and current SEP acceleration models. Furthermore, the outstanding issues that constitute a knowledge gap in the field will be presented and discussed, as well as future directions and expected advances from the observational and modeling perspective, also in view of the unique observations provided by the upcoming Solar Orbiter and Solar Probe Plus missions. Acknowledgement: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.

  3. Solar Energetic Particle Events: Phenomenology and Prediction

    NASA Astrophysics Data System (ADS)

    Gabriel, S. B.; Patrick, G. J.

    2003-04-01

    Solar energetic particle events can cause major disruptions to the operation of spacecraft in earth orbit and outside the earth's magnetosphere and have to be considered for EVA and other manned activities. They may also have an effect on radiation doses received by the crew flying in high altitude aircraft over the polar regions. The occurrence of these events has been assumed to be random, but there would appear to be some solar cycle dependency with a higher annual fluence occuring during a 7 year period, 2 years before and 4 years after the year of solar maximum. Little has been done to try to predict these events in real-time with nearly all of the work concentrating on statistical modelling. Currently our understanding of the causes of these events is not good. But what are the prospects for prediction? Can artificial intelligence techniques be used to predict them in the absence of a more complete understanding of the physics involved? The paper examines the phenomenology of the events, briefly reviews the results of neural network prediction techniques and discusses the conjecture that the underlying physical processes might be related to self-organised criticality and turblent MHD flows.

  4. Cavitation Bubble Nucleation by Energetic Particles

    SciTech Connect

    West, C.D.

    1998-12-01

    In the early sixties, experimental measurements using a bubble chamber confirmed quantitatively the thermal spike theory of bubble nucleation by energetic particles: the energy of the slow, heavy alpha decay recoils used in those experiments matched the calculated bubble nucleation energy to within a few percent. It was a triumph, but was soon to be followed by a puzzle. Within a couple of years, experiments on similar liquids, but well below their normal boiling points, placed under tensile stress showed that the calculated bubble nucleation energy was an order of magnitude less than the recoil energy. Why should the theory work so well in the one case and so badly in the other? How did the liquid, or the recoil particle, "know" the difference between the two experiments? Another mathematical model of the same physical process, introduced in 1967, showed qualitatively why different analyses would be needed for liquids with high and low vapor pressures under positive or negative pressures. But, the quantitative agreement between the calculated nucleation energy and the recoil energy was still poor--the former being smaller by a factor of two to three. In this report, the 1967 analysis is extended and refined: the qualitative understanding of the difference between positive and negative pressure nucleation, "boiling" and "cavitation" respectively, is retained, and agreement between the negative pressure calculated to be needed for nucleation and the energy calculated to be available is much improved. A plot of the calculated negative pressure needed to induce bubble formation against the measured value now has a slope of 1.0, although there is still considerable scatter in the individual points.

  5. Energetic particles over Io's polar caps

    NASA Astrophysics Data System (ADS)

    Williams, D. J.; Thorne, R. M.

    2003-11-01

    We present results obtained from the Galileo satellite's Energetic Particles Detector during its final two encounters in 2001 with Jupiter's moon Io. These encounters returned the first data from just above Io's polar caps. They complement previous low-latitude data and provide a new perspective of Io's interaction with Jupiter's magnetosphere and ionosphere. The evolution of electron and ion distributions was measured from the upstream region throughout the polar cap traversals. From the time of initial field contact with Io and continuing throughout the encounter these distributions evolve in a manner consistent with adiabatic motion along the Io-Jupiter field line. At encounter all particles develop narrow trapped-like distributions indicative of the creation of a near-Io magnetic bottle caused by an enhancement of field at Io's upstream surface. The measured pitch angle distributions indicate a field enhancement of up to 10%-15% higher than the field observed at Galileo's position. Distribution evolution times agree roughly with particle bounce times on the Io-Jupiter field line. The ion distribution evolution times provide an estimate of ˜3-7 km/s for the field line convection speed across Io's polar caps, a value small (˜10%) compared with the upstream convection speed. Along with these trapped distributions, beams of ions and electrons are observed streaming into Io's polar caps throughout the encounters. The continued observation of ion beams across the polar cap is consistent with their half-bounce times. The data further indicate that the convection speed may vary as the polar cap is traversed. The one exception to the adiabatic particle behavior discussed above is the observation of intense electron beams streaming into Io's polar caps. The polar cap electron beams are similar to those previously measured in Io's wake [, 1996] and apparently originate from the same source. The source has been located at low (˜0.5 RJ) altitudes on the Io-Jupiter field

  6. The Two Sources of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Reames, Donald V.

    2013-06-01

    Evidence for two different physical mechanisms for acceleration of solar energetic particles (SEPs) arose 50 years ago with radio observations of type III bursts, produced by outward streaming electrons, and type II bursts from coronal and interplanetary shock waves. Since that time we have found that the former are related to "impulsive" SEP events from impulsive flares or jets. Here, resonant stochastic acceleration, related to magnetic reconnection involving open field lines, produces not only electrons but 1000-fold enhancements of 3He/4He and of ( Z>50)/O. Alternatively, in "gradual" SEP events, shock waves, driven out from the Sun by coronal mass ejections (CMEs), more democratically sample ion abundances that are even used to measure the coronal abundances of the elements. Gradual events produce by far the highest SEP intensities near Earth. Sometimes residual impulsive suprathermal ions contribute to the seed population for shock acceleration, complicating the abundance picture, but this process has now been modeled theoretically. Initially, impulsive events define a point source on the Sun, selectively filling few magnetic flux tubes, while gradual events show extensive acceleration that can fill half of the inner heliosphere, beginning when the shock reaches ˜2 solar radii. Shock acceleration occurs as ions are scattered back and forth across the shock by resonant Alfvén waves amplified by the accelerated protons themselves as they stream away. These waves also can produce a streaming-limited maximum SEP intensity and plateau region upstream of the shock. Behind the shock lies the large expanse of the "reservoir", a spatially extensive trapped volume of uniform SEP intensities with invariant energy-spectral shapes where overall intensities decrease with time as the enclosing "magnetic bottle" expands adiabatically. These reservoirs now explain the slow intensity decrease that defines gradual events and was once erroneously attributed solely to slow

  7. Energetic storm particle events in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Mcdonald, F.; Trainor, J.; Mihalov, J.; Wolfe, J.; Webber, W.

    1981-01-01

    The evolution of energetic particle events with increasing heliocentric distance is studied through events of Pioneers 10 and 11. Beyond 12 AU the events become the dominant type of solar particle event at 1 AU, and the combined effects of adiabatic cooling and volume expansion rule out the possibility that the particles represent the confinement of the original particle population behind the shock. It is not established whether the particles originate from the solar wind by injection via post-shock enhancements or are energetic solar particles further energized by the shock, although their very long lifetime favors the solar wind origin.

  8. Role of Alfven instabilities in energetic ion transport

    SciTech Connect

    Bernabei, S.; Gorelenkov, N. N.; Budny, R.; Fredrickson, E. D.; Hosea, J. C.; Majeski, R.; Phillips, C. K.; Wilson, J. R.

    1999-09-20

    Experiments with plasma heating by waves at the ion cyclotron resonance of a minority species have shown that the heating efficiency degrades above a certain power threshold. It is found that this threshold is due to the destabilization of shear Alfven waves, which causes loss of fast ions. There are two distinct regimes characterized by low q{sub a} and high q{sub a}. In the first case, the fast ion distribution created by ICRF, lies entirely inside r{sub q=1}, away from the location of global TAE. This situation leads to the formation of a very strong fast ion population which stabilizes the sawteeth, but also excites Energetic Particle Modes (EPM), which transport fast ions outside r{sub q=1} causing the giant crash. At higher q{sub a}, the widening of the Alfven gap due to the steeper q profile, brings the global TAE ''in contact'' with the fast ion distribution. This results in an immediate and continuous depletion of fast ions from the core, which prevents the formation of the monster sawtooth and the excitation of EPM. (c) 1999 American Institute of Physics.

  9. Solar energetic particle anisotropies and insights into particle transport

    NASA Astrophysics Data System (ADS)

    Leske, R. A.; Cummings, A. C.; Cohen, C. M. S.; Mewaldt, R. A.; Labrador, A. W.; Stone, E. C.; Wiedenbeck, M. E.; Christian, E. R.; Rosenvinge, T. T. von

    2016-03-01

    As solar energetic particles (SEPs) travel through interplanetary space, their pitch-angle distributions are shaped by the competing effects of magnetic focusing and scattering. Measurements of SEP anisotropies can therefore reveal information about interplanetary conditions such as magnetic field strength, topology, and turbulence levels at remote locations from the observer. Onboard each of the two STEREO spacecraft, the Low Energy Telescope (LET) measures pitch-angle distributions for protons and heavier ions up to iron at energies of about 2-12 MeV/nucleon. Anisotropies observed using LET include bidirectional flows within interplanetary coronal mass ejections, sunward-flowing particles when STEREO was magnetically connected to the back side of a shock, and loss-cone distributions in which particles with large pitch angles underwent magnetic mirroring at an interplanetary field enhancement that was too weak to reflect particles with the smallest pitch angles. Unusual oscillations in the width of a beamed distribution at the onset of the 23 July 2012 SEP event were also observed and remain puzzling. We report LET anisotropy observations at both STEREO spacecraft and discuss their implications for SEP transport, focusing exclusively on the extreme event of 23 July 2012 in which a large variety of anisotropies were present at various times during the event.

  10. The Modeling of Pickup Ion or Energetic Particle Mediated Plasmas

    NASA Astrophysics Data System (ADS)

    Zank, G. P.; Mostafavi, P.; Hunana, P.

    2016-05-01

    Suprathermal energetic particles, such as solar energetic particles (SEPs) in the inner heliosphere and pickup ions (PUIs) in the outer heliosphere and the very local interstellar medium, often form a thermodynamically dominant component in their various environments. In the supersonic solar wind beyond > 10 AU, in the inner heliosheath (IHS), and in the very local interstellar medium (VLISM), PUIs do not equilibrate collisionally with the background plasma. Similarly, SEPs do not equilibrate collisionally with the background solar wind in the inner heliosphere. In the absence of equilibration between plasma components, a separate coupled plasma description for the energetic particles is necessary. Using a collisionless Chapman-Enskog expansion, we derive a closed system of multi-component equations for a plasma comprised of thermal protons and electrons, and suprathermal particles (SEPs, PUIs). The energetic particles contribute an isotropic scalar pressure to leading order, a collisionless heat flux at the next order, and a collisionless stress tensor at the second-order. The collisionless heat conduction and viscosity in the multi-fluid description results from a nonisotropic energetic particle distribution. A simpler single-fluid MHD-like system of equations with distinct equations of state for both the background plasma and the suprathermal particles is derived. We note briefly potential pitfalls that can emerge in the numerical modeling of collisionless plasma flows that contain a dynamically important energetic particle component.

  11. Diagnostics of Solar Flare Energetic Particles

    NASA Astrophysics Data System (ADS)

    Mallik, Procheta; Brown, J. C.; MacKinnon, A. L.

    2009-05-01

    For work on my thesis dissertation, we have been studying some energetic processes in solar flares. On our work on Hard X-ray (HXR) emission from flares, we have shown that recombination emission can exceed the bremsstrahlung HXR flux for certain flare conditions. We will show some spectral features characteristic of non-thermal recombination HXR emission and will suggest how it plays a significant role in the flare HXR continuum, something that has been ignored in the past. It is important to note that these results could demand a reconsideration of the numbers of accelerated electrons since recombination can be much more efficient in producing HXR photons than bremsstrahlung. In related work on diagnosing particle acceleration in flares, we also have an interest in studying solar neutrons. To this end, we will present our work done with new-age neutron detectors developed by our colleagues at the University of New Hampshire. Using laboratory and simulated data from the detector to produce its response matrix, we then employ regularisation and deconvolution techniques to produce encouraging results for data inversion. As a corollary, we have also been reconsidering the role of inverse Compton (IC) scattering of photospheric photons. Gamma-ray observations clearly show the presence of 100 MeV electrons and positrons in the solar corona, by-products of GeV energy ions. Here we will present results of IC scattering of such photons taking proper account of radiation field geometry near the solar surface. If observed, such radiation would let us determine the number of secondary positrons produced in large flares, contributing to a full picture of ion acceleration and to predicting neutron fluxes to be encountered by future inner heliosphere space missions. This work is supported by a UK STFC Rolling Grant and a Dorothy Hodgkin's Scholarship (PM).

  12. Energetic particle characteristics of magnetotail flux ropes

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Klecker, B.; Hovestadt, D.; Gloeckler, G.; Ipavich, F. M.; Galvin, A. B.

    1985-01-01

    During the recent ISEE-3 Geotail Mission three events have been identified from the magnetometer data which are consistent with a spacecraft crossing of a magnetotail flux rope. Energetic electron and proton observations obtained by the Max-Planck-Institut/University of Maryland sensor system during two of the possible flux rope events are presented. During one event remote sensing of the flux rope with energetic protons reveals that the flux rope is crossed by the spacecraft from south to north. This allows determination of the bandedness of the magnetic field twist and of the flux rope velocity relative to the spacecraft. A minimal flux rope radius of 3 earth radii is derived. Energetic proton intensity is highest just inside of the flux rope and decreases towards the core. Energetic electrons are streaming tailward near the outer boundary, indicating openness of the field lines, and are isotropic through the inner part of the flux rope.

  13. The acceleration and propagation of solar flare energetic particles

    NASA Technical Reports Server (NTRS)

    Forman, M. A.; Ramaty, R.; Zweibel, E. G.; Holzer, T. E. (Editor); Mihalas, D. (Editor); Sturrock, P. A. (Editor); Ulrich, R. K. (Editor)

    1982-01-01

    Observations and theories of particle acceleration in solar flares are reviewed. The most direct signatures of particle acceleration in flares are gamma rays, X-rays and radio emissions produced by the energetic particles in the solar atmosphere and energetic particles detected in interplanetary space and in the Earth's atmosphere. The implication of these observations are discussed. Stochastic and shock acceleration as well as acceleration in direct electric fields are considered. Interplanetary particle propagation is discussed and an overview of the highlights of both current and promising future research is presented.

  14. NANOSTRUCTURE PATTERNING UNDER ENERGETIC PARTICLE BEAM IRRADIATION

    SciTech Connect

    Wang, Lumin; Lu, Wei

    2013-01-31

    Energetic ion bombardment can lead to the development of complex and diverse nanostructures on or beneath the material surface through induced self-organization processes. These self-organized structures have received particular interest recently as promising candidates as simple, inexpensive, and large area patterns, whose optical, electronic and magnetic properties are different from those in the bulk materials [1-5]. Compared to the low mass efficiency production rate of lithographic methods, these self-organized approaches display new routes for the fabrication of nanostructures over large areas in a short processing time at the nanoscale, beyond the limits of lithography [1,4]. Although it is believed that surface nanostructure formation is based on the morphological instability of the sputtered surface, driven by a kinetic balance between roughening and smoothing actions [6,7], the fundamental mechanisms and experimental conditions for the formation of these nanostructures has still not been well established, the formation of the 3-D naopatterns beneath the irradiated surface especially needs more exploration. During the last funding period, we have focused our efforts on irradiation-induced nanostructures in a broad range of materials. These structures have been studied primarily through in situ electron microscopy during electron or ion irradiation. In particular, we have performed studies on 3-D void/bubble lattices (in metals and CaF2), embedded sponge-like porous structure with uniform nanofibers in irradiated semiconductors (Ge, GaSb, and InSb), 2-D highly ordered pattern of nanodroplets (on the surface of GaAs), hexagonally ordered nanoholes (on the surface of Ge), and 1-D highly ordered ripple and periodic arrays (of Cu nanoparticles) [3,8-11]. The amazing common feature in those nanopatterns is the uniformity of the size of nanoelements (nanoripples, nanodots, nanovoids or nanofibers) and the distance separating them. Our research focuses on the

  15. Compositions of energetic particle populations in interplanetary space

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1979-01-01

    Observations of helium and heavier particles with energies below about 10 to 20 MeV/nucleon are discussed with emphasis on the composition of solar flare particles, corotating energetic particle streams, and the anomalous cosmic ray component. Future advances expected from results obtained from ISEE -3, Voyager, and the international solar polar spacecraft are reviewed.

  16. Theory of energetic trapped particle-induced resistive interchange-ballooning modes

    SciTech Connect

    Biglari, H.; Chen, L.

    1986-02-01

    A theory describing the influence of energetic trapped particles on resistive interchange-ballooning modes in tokamaks is presented. It is shown that a population of hot particles trapped in the region of adverse curvature can resonantly interact with and destabilize the resistive interchange mode, which is stable in their absence because of favorable average curvature. The mode is different from the usual resistive interchange mode not only in its destabilization mechanism, but also in that it has a real component to its frequency comparable to the precessional drift frequency of the rapidly circulating energetic species. Corresponding growth rate and threshold conditions for this trapped-particle-driven instability are derived and finite banana width effects are shown to have a stabilizing effect on the mode. Finally, the ballooning/tearing dispersion relation is generalized to include hot particles, so that both the ideal and the resistive modes are derivable in the appropriate limits. 23 refs., 7 figs.

  17. Energetic particle destabilization of shear Alfven waves in stellarators and tokamaks

    SciTech Connect

    Spong, D.A.; Carreras, B.A.; Hedrick, C.L.; Leboeuf, J.N.; Weller, A.

    1994-12-31

    An important issue for ignited devices is the resonant destabilization of shear Alfven waves by energetic populations. These instabilities have been observed in a variety of toroidal plasma experiments in recent years, including: beam-destabilized toroidal Alfven instabilities (TAE) in low magnetic field tokamaks, ICRF destabilized TAE`s in higher field tokamaks, and global Alfven instabilities (GAE) in low shear stellarators. In addition, excitation and study of these modes is a significant goal of the TFIR-DT program and a component of the ITER physics tasks. The authors have developed a gyrofluid model which includes the wave-particle resonances necessary to excite such instabilities. The TAE linear mode structure is calculated nonperturbatively, including many of the relevant damping mechanisms, such as: continuum damping, non-ideal effects (ion FLR and electron collisionality), and ion/electron Landau damping. This model has been applied to both linear and nonlinear regimes for a range of experimental cases using measured profiles.

  18. Energetic particles in space - The Giotto mission to Halley's comet

    NASA Astrophysics Data System (ADS)

    O'Sullivan, D.; Thompson, A.; Daly, P.; Kirsch, E.; McKenna-Lawlor, S.

    1988-03-01

    The Energetic Particle Analyzer (EPA) experiment, which was part of the Giotto mission to study the environment of Halley's comet, is discussed. The EPA instrument is described and the results of the study are summarized. The particle studies discussed cover the energy range from tens of keV to the MeV region. The observation of omnidirectional particle fluxes and ion and magnetic field intensity are examined. It is suggested that there is no striking correlation between measurements of magnetic field intensity and direction and variations in the energetic-particle fluxes.

  19. Transport of Energetic Particles by Microturbulence in Magnetized Plasmas

    SciTech Connect

    Zhang Wenlu; Lin Zhihong; Chen Liu

    2008-08-29

    Transport of energetic particles by the microturbulence in magnetized plasmas is studied in gyrokinetic simulations of the ion temperature gradient turbulence. The probability density function of the ion radial excursion is found to be very close to a Gaussian, indicating a diffusive transport process. The particle diffusivity can thus be calculated from a random walk model. The diffusivity is found to decrease drastically for high energy particles due to the averaging effects of the large gyroradius and orbit width, and the fast decorrelation of the energetic particles with the waves.

  20. Energetic particle transport and acceleration within the interplanetary medium

    NASA Astrophysics Data System (ADS)

    Dalla, Silvia

    2016-07-01

    The propagation through space of energetic particles accelerated at the Sun and in the inner heliosphere is governed by the characteristics of the interplanetary magnetic field. At large scales, the average Parker spiral configuration, on which transient magnetic structures may be superimposed, dominates the transport, while at smaller scales turbulence scatters the particles and produces field line meandering. This talk will review the classical 1D approach to interplanetary transport, mainly applied to Solar Energetic Particles (SEPs), as well as alternative models which allow for effects such as scattering perpendicular to the average magnetic field and field line meandering. The recently emphasized role of drifts in the propagation of SEPs will be discussed. The presentation will also review processes by which particle acceleration takes place within the interplanetary medium and the overall way in which acceleration and transport shape in-situ observations of energetic particles.

  1. Resistance probe for energetic particle dosimetry

    DOEpatents

    Wampler, W.R.

    A probe for determining the energy and flux of particles in a plasma comprises a carbon film adapted to be exposed to the plasma, the film having an electrical resistance which is related to the number of particles impacting the film, contacts for passing an electrical current throught the film, and contacts for determining the electrical resistance of the film. An improved method for determining the energy or flux of particles in a plasma is also disclosed.

  2. Energetic Particles and Upstream Waves at Co-rotating Shocks

    NASA Astrophysics Data System (ADS)

    Smith, Edward J.; Zhou, Xiaoyan

    2010-03-01

    We report a study of energetic ion acceleration at shocks bounding co-rotating interaction regions (CIRs). Archived data obtained by Ulysses magnetic field, solar wind and energetic particle investigations at low latitude CIRs have been assembled and analyzed. The statistical relations between various properties of 22 Forward shocks, energetic particles and upstream heliospheric magnetic field fluctuations are presented. No statistically significant correlations are found between the shock compression ratio, r, or the particle intensity, jp, or the energetic particle spectral index, s, and the shock normal-upstream field angle, θBn. Furthermore, a theoretical relation between the particle spectral index and shock compression is not consistent with the observed values of s and r. The particle intensities are poorly correlated with the power in upstream heliospheric magnetic field fluctuations contrary to our preliminary study of fewer shocks. We conclude that many of the expectations of Diffusive Shock Theory are not supported by this data set but it is too early to decide whether some key measurement is missing or the theory needs reconsideration.

  3. Energetic particles as probes of solar wind disturbances

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Richardson, I. G.; Wibberenz, G.

    1995-01-01

    We have investigated the response of particles, in the energy range approximately 1-5000 MeV, to interplanetary shocks and coronal ejecta. Shocks can accelerate particles or cause decreases in particle densities. Ejecta cause decreases. Thus particle observations can provide information about solar wind disturbances. Of particular interest is that the boundaries of ejecta can often be more readily identified from approximately l GeV particle decrease observations than from most other phenomena associated with ejecta. We will discuss the properties of less energetic shocks and ejecta and compare them with those of the more energetic events which are normally discussed in the context of Forbush decreases, large proton events, etc. We use data from both Helios spacecraft and IMP 8 which allows some spatial variations to be studied.

  4. Energetic particles in geospace: Physics and space weather effects

    NASA Astrophysics Data System (ADS)

    Daglis, I.

    2013-09-01

    Geospace is populated by charged particles covering a wide range of energies and densities. Influenced by electromagnetic fields and waves, a subset of these particles are accelerated and driven into the inner magnetosphere, creating the storm-time ring current and the radiation belts - the two dominant energetic particle populations in geospace. The acceleration processes are associated with a variety of space weather related phenomena, some of which are detrimental for space infrastructure and ground facilities alike. We present recent advances in our understanding of the complex interplay of particles, fields and waves in geospace, with an emphasis on the role of magnetic storms and wave-particle interactions.

  5. Energetics of Mixed Phase Cloud Particle Interactions

    NASA Astrophysics Data System (ADS)

    Vidaurre, G.; Hallett, J.

    2005-12-01

    The ratio of the kinetic to surface energy of a crystal or a drop on impact gives a measure of the available energy for break-up and splash. Such a break-up process may influence particle collision and also particle observations at aircraft speed. The detail physical processes of the impact determines how the kinetic energy is distributed: 1) part retained by bouncing particles, 2) to create new surfaces during break-up, 3) to dislocate or melt part of the crystal, and 4) converted to thermal energy through viscous dissipation of deforming liquid or displacing air on impact. Extensive break-up of 2% of the crystal or melting of 6% is enough to explain the crystal kinetic energy losses during the encounter at aircraft speed. Ice crystals from convective and stratiform clouds and continental clouds were collected in formvar solution by continuous replicator and also were video-recorded following impact on optical flat of a Cloudscope. Particle sizes were classified in bins, the expected number of fragments being given by an exponential function for ice particles with effective diameter between 5 μm and 2500 μm, and 70% standard deviation. Regions of crystals broken into a few fragments account for 0.6% of the kinetic energy loss; in other parts severe break-up makes it impossible to measure the fracture length. Knowledge regarding ice and water interaction in Mixed-Phase clouds and also with the aircraft instruments provides basic underpinning for characterization of ice particle impact. Further, detail of the fracture process may also be of importance in relation to electrical properties of the particle after impaction or break-up. These conclusions are of major operational importance for prediction of the icing process itself, having implications for both aircraft icing and particle measurement instrumentation.

  6. CIRCUMSOLAR ENERGETIC PARTICLE DISTRIBUTION ON 2011 NOVEMBER 3

    SciTech Connect

    Gómez-Herrero, R.; Blanco, J.J.; Rodríguez-Pacheco, J.; Dresing, N.; Klassen, A.; Heber, B.; Banjac, S.; Lario, D.; Agueda, N.; Malandraki, O. E.

    2015-01-20

    Late on 2011 November 3, STEREO-A, STEREO-B, MESSENGER, and near-Earth spacecraft observed an energetic particle flux enhancement. Based on the analysis of in situ plasma and particle observations, their correlation with remote sensing observations, and an interplanetary transport model, we conclude that the particle increases observed at multiple locations had a common single-source active region and the energetic particles filled a very broad region around the Sun. The active region was located at the solar backside (as seen from Earth) and was the source of a large flare, a fast and wide coronal mass ejection, and an EIT wave, accompanied by type II and type III radio emission. In contrast to previous solar energetic particle events showing broad longitudinal spread, this event showed clear particle anisotropies at three widely separated observation points at 1 AU, suggesting direct particle injection close to the magnetic footpoint of each spacecraft, lasting for several hours. We discuss these observations and the possible scenarios explaining the extremely broad particle spread for this event.

  7. Kinetic Effects of Energetic Particles on Resistive MHD Stability

    SciTech Connect

    Takahashi, R.; Brennan, D. P.; Kim, C. C.

    2009-04-03

    We show that the kinetic effects of energetic particles can play a crucial role in the stability of the m/n=2/1 tearing mode in tokamaks (e.g., JET, JT-60U, and DIII-D), where the fraction of energetic particle {beta}{sub frac} is high. Using model equilibria based on DIII-D experimental reconstructions, the nonideal MHD linear stability of cases unstable to the 2/1 mode is investigated including a {delta}f particle-in-cell model for the energetic particles coupled to the nonlinear 3D resistive MHD code NIMROD[C. C. Kim et al., Phys. Plasmas 15, 072507 (2008)]. It is observed that energetic particles have significant damping and stabilizing effects at experimentally relevant {beta}, {beta}{sub frac}, and S, and excite a real frequency of the 2/1 mode. Extrapolation of the results is discussed for implications to JET and ITER, where the effects are projected to be significant.

  8. Stochastic Particle Acceleration in Turbulence Generated by Magnetorotational Instability

    NASA Astrophysics Data System (ADS)

    Kimura, Shigeo S.; Toma, Kenji; Suzuki, Takeru K.; Inutsuka, Shu-ichiro

    2016-05-01

    We investigate stochastic particle acceleration in accretion flows. It is believed that magnetorotational instability (MRI) generates turbulence inside accretion flows and that cosmic rays (CRs) are accelerated by the turbulence. We calculate equations of motion for CRs in the turbulent fields generated by MRI with the shearing box approximation and without back reaction to the field. Our results show that the CRs randomly gain or lose their energy through interaction with the turbulent fields. The CRs diffuse in the configuration space anisotropically: the diffusion coefficient in the direction of the unperturbed flow is about 20 times higher than the Bohm coefficient, while those in the other directions are only a few times higher than the Bohm. The momentum distribution is isotropic and its evolution can be described by the diffusion equation in momentum space where the diffusion coefficient is a power-law function of the CR momentum. We show that the shear acceleration works efficiently for energetic particles. We also cautiously note that in the shearing box approximation, particles that cross the simulation box many times along the radial direction undergo unphysical runaway acceleration by the Lorentz transformation, which needs to be taken into account with special care.

  9. Energetic particles in Saturn's middle magnetosphere

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. Energetic Charged Particle Injections at Saturn

    NASA Astrophysics Data System (ADS)

    Paranicas, C.; Mitchell, D. G.; Hamilton, D. C.; Krimigis, S. M.; Mauk, B. H.; Brandt, P. C.; Carbary, J. F.; Rymer, A. M.

    2008-12-01

    The Cassini spacecraft has been in Saturn orbit for over 4 years. The Magnetospheric Imaging Instrument (MIMI) is a charged and neutral particle instrument with three separate sensors. On every perigee pass to date, data taken by MIMI reveal the presence of very recent and/or older charged particle injections. For our purposes, injections are spatially confined populations whose fluxes are recognizably greater than the fluxes of the ambient population. These populations are transient in nature and our previous work and the work of others has shown that they evolve essentially through the usual corotation and gradient-curvature drifts. However, it is not completely understood whether all of the injections observed by MIMI, in the few keV to MeV energy range, are associated with the same physical mechanism. Injections can, in principle, be caused by local accelerations of a fraction of the denser, lower energy particles. On the other hand, injections may also be associated with processes that transport particles radially, such as in magnetospheric flux tube interchange or large scale magnetospheric reconfigurations. In this paper, we will present a survey of the data set, an organization of the injections by their properties, and some hypotheses about how these properties reveal information about the underlying physical generation mechanisms.

  11. Sawtooth stabilization by energetic trapped particles

    SciTech Connect

    White, R.B.; Rutherford, P.H.; Colestock, P.; Bussac, M.N.

    1988-03-01

    Recent experiments involving high power radio-frequency heating of a tokamak plasma show strong suppression of the sawtooth oscillation. A high energy trapped particle population is shown to have a strong stabilizing effect on the internal resistive kink mode. Numerical calculations are in reasonable agreement with experiment. 13 refs., 2 figs.

  12. Connecting Shock Parameters to the Radiation Hazard from Energetic Particles

    NASA Technical Reports Server (NTRS)

    Berdichevsky, Daniel B.; Reames, Donald V.; Lepping, Ronald P.; Schwenn, Rainer W.

    2004-01-01

    We use data from Helios, IMP-8, and other spacecraft (e.g. ISEE) to systematically investigate solar energetic particle (SEP) events from different longitudes and distances in the heliosphere. The purpose of the project is to assess empirically the connection between the morphology of the travelling shock and strength with observed enhancements in the flow of energized particles in shock accelerated particle (SEP) events (also often identified as "gradual" solar energetic particle events). Activities during this first year centered on the organization of the SEPs events and their correlation with solar wind observations at multiple spacecraft locations. From an identified list of more than 30 SEPs events at multiple spacecraft locations, currently four single cases for detailed study were selected and are in an advance phase of preparation for publication. Preliminary results of these four cases were presented at AGU Spring and Fall 2003 meetings, and other meetings on SEPs.

  13. Energetic particles flux experiment for ISEE mother/daughter spacecraft

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.

    1981-01-01

    The history of the energetic particle experiments on the International Sun Earth Explorer 1 and 2 spacecraft is outlined, and descriptions of the instruments are given. The inflight performance and data analysis are summarized. The research is completed and ongoing are described and a bibliography is included.

  14. Observations of solar energetic particles at a synchronous orbit

    NASA Technical Reports Server (NTRS)

    Takenaka, T.; Ohi, Y.; Yanagimachi, T.; Ito, K.; Kohno, T.; Sakurai, K.

    1985-01-01

    The Space Environment Monitors (SEM) on board the Japanese geostationary meteorological satellites (GMS-1 and GMS-2) observed energetic protons, alpha particles and electrons continuously for February 1978 to September 1984. The satellites were at 6.6 Earth radii above 140 deg E equator.

  15. The Energetic Particles in Shock-ICME Interaction Structures

    NASA Astrophysics Data System (ADS)

    Shen, C.

    2015-12-01

    Previous results show that the energetic particles intensity will decreased in the ICMEs. But, in the year of 2008, Shen et al. reported a definite case that the intensity of solar energetic particles (SEP) in the shock-MC interaction structure increase greatly. They further found that such enhancement is the main cause of the largest SEP event in solar cycle 23. The questions remained are: Did all the shock-ICME(MC) structure cause the enhancement of the SEP intensity? If not, why it only happened in some events? Is there any other mechanism which can make the energetic particle intensity in ICME enhanced? To answer these questions, the SEP signatures in all ICMEs including the shock-ICME interaction structures from 1996 to 2014 are studied detail. It is found that the SEP intensities enhanced in about half of the shock-ICME interaction events. Meanwhile, large fraction of energetic particles intensity enhanced ICMEs are interacted with shocks. To find the possible condition and physical mechanismof such enhancement, the parameters of the shock, ICME(MC) and etc. are detailed analyzed.

  16. Scalings of energetic particle transport by ion temperature gradient microturbulence

    SciTech Connect

    Zhang Wenlu; Decyk, Viktor; Holod, Ihor; Xiao Yong; Lin Zhihong; Chen Liu

    2010-05-15

    Transport scaling of energetic particles by ion temperature gradient microturbulence in magnetized plasmas is studied in massively paralleled gyrokinetic particle-in-cell simulations. It is found that the diffusivity decreases drastically at high particles energy (E) to plasma temperature (T) ratio because of the averaging effects of the large gyroradius and drift-orbit width, and the fast wave-particle decorrelation. At high energy, the diffusivity follows a (E/T){sup -1} scaling for purely passing particles, a (E/T){sup -2} scaling for deeply trapped particles and a (E/T){sup -1} scaling for particles with an isotropic velocity distribution since the diffusivity therein is contributed mostly by the passing particles.

  17. Isotopic overabundances and the energetic particle model of solar flares

    NASA Technical Reports Server (NTRS)

    Perez-Enriquez, R.; Bravo, S.

    1985-01-01

    According to the energetic particle model of solar flares particles are efficiently accelerated in the magnetic field loop of an active region (AR) by hydromagnetic turbulence. It is demonstrated that the isotopic overabundances observed in some flares are not a consequence of the flare itself but are characteristic of the plasma in the AR. Only when a flare releases the plasma into the interplanetary space it is possible to observe this anomalous composition at spacecraft locations.

  18. Energetic particles and magnetic field measurements at Comet Halley

    NASA Astrophysics Data System (ADS)

    Osullivan, D.; Thompson, A.; McKenna-Lawlor, S.; Kirsch, E.; Wenzel, K.-P.; Neubauer, F. M.

    1986-12-01

    Studies of energetic charged particles in the environment of comet Halley, based on data from the EPA instrument on the Giotto spacecraft, are presented. Investigation of the lowest energy channels (p,e; 26 to 46 keV) of Telescopes 1 and 3 are reported. Investigation of the particle data in relation to magnetic field measurements made during 13 and 14 March 1986 are discussed. Overall flux patterns are similar to those of higher energy channels.

  19. Tangling clustering instability for small particles in temperature stratified turbulence

    NASA Astrophysics Data System (ADS)

    Elperin, T.; Kleeorin, N.; Liberman, M.; Rogachevskii, I.

    2013-08-01

    We study tangling clustering instability of inertial particles in a temperature stratified turbulence with small finite correlation time. It is shown that the tangling mechanism in the temperature stratified turbulence strongly increases the degree of compressibility of particle velocity field. This results in the strong decrease of the threshold for the excitation of the tangling clustering instability even for small particles. The tangling clustering instability in the temperature stratified turbulence is essentially different from the inertial clustering instability that occurs in non-stratified isotropic and homogeneous turbulence. While the inertial clustering instability is caused by the centrifugal effect of the turbulent eddies, the mechanism of the tangling clustering instability is related to the temperature fluctuations generated by the tangling of the mean temperature gradient by the velocity fluctuations. Temperature fluctuations produce pressure fluctuations and cause particle accumulations in regions with increased instantaneous pressure. It is shown that the growth rate of the tangling clustering instability is by sqrtRe (ell _0 / L_T)^2 / (3 Ma)^4 times larger than that of the inertial clustering instability, where Re is the Reynolds number, Ma is the Mach number, ℓ0 is the integral turbulence scale, and LT is the characteristic scale of the mean temperature variations. It is found that depending on the parameters of the turbulence and the mean temperature gradient there is a preferential particle size at which the particle clustering due to the tangling clustering instability is more effective. The particle number density inside the cluster after the saturation of this instability can be by several orders of magnitude larger than the mean particle number density. It is also demonstrated that the evaporation of droplets drastically changes the tangling clustering instability, e.g., it increases the instability threshold in the droplet radius. The

  20. Virtual Energetic Particle Observatory for the Heliospheric Data Environment

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.; Armstrong, T. P.; Hill, M. E.; Lal, N.; McGuire, R. E.; McKibben, R. B.; Narock, T. W.; Szabo, A.; Tranquille, C.

    2007-01-01

    The heliosphere is pervaded by interplanetary energetic particles, traditionally also called cosmic rays, from solar, internal heliospheric, and galactic sources. The particles species of interest to heliophysics extend from plasma energies to the GeV energies of galactic cosmic rays still measurably affected by heliospheric modulation and the still higher energies contributing to atmospheric ionization. The NASA and international Heliospheric Network of operational and legacy spacecraft measures interplanetary fluxes of these particles. Spatial coverage extends from the inner heliosphere and geospace to the heliosheath boundary region now being traversed by Voyager 1 and soon by Voyager 2. Science objectives include investigation of solar flare and coronal mass ejection events, acceleration and transport of interplanetary particles within the inner heliosphere, cosmic ray interactions with planetary surfaces and atmospheres, sources of suprathermal and anomalous cosmic ray ions in the outer heliosphere, and solar cycle modulation of galactic cosmic rays. The Virtual Energetic Particle Observatory (VEPO) will improve access and usability of selected spacecraft and sub-orbital NASA heliospheric energetic particle data sets as a newly approved effort within the evolving heliophysics virtual observatory environment. In this presentation, we will describe current VEPO science requirements, our initial priorities and an overview of our strategy to implement VEPO rapidly and at minimal cost by working within the high-level framework of the Virtual Heliospheric Observatory (VHO). VEPO will also leverage existing data services of NASA's Space Physics Data Facility and other existing capabilities of the U.S. and international heliospheric research communities.

  1. Interaction of Energetic Particles with Discontinuities Upstream of Strong Shocks

    NASA Astrophysics Data System (ADS)

    Malkov, Mikhail; Diamond, Patrick

    2008-11-01

    Acceleration of particles in strong astrophysical shocks is known to be accompanied and promoted by a number of instabilities which are driven by the particles themselves. One of them is an acoustic (also known as Drury's) instability driven by the pressure gradient of accelerated particles upstream. The generated sound waves naturally steepen into shocks thus forming a shocktrain. Similar magnetoacoustic or Alfven type structures may be driven by pick-up ions, for example. We consider the solutions of kinetic equation for accelerated particles within the shocktrain. The accelerated particles are assumed to be coupled to the flow by an intensive pitch-angle scattering on the self-generated Alfven waves. The implications for acceleration and confinement of cosmic rays in this shock environment will be discussed.

  2. Energetic particle microsignatures of Saturn's satellites

    NASA Technical Reports Server (NTRS)

    Carbary, J. F.; Krimigis, S. M.; Ip, W.-H.

    1983-01-01

    During Voyager's 1980 and 1981 encounters with Saturn, the low energy charged particle experiment observed satellite microsignatures in ions and electrons. Each of the five major satellites within Titan's orbit were associated with at least one absorption feature in the high time resolution data. Microsignatures are usually observed in the corotational wake region within about 25 deg in azimuth of a satellite, and do not generally occur at times predicted by a centered, aligned dipole. A better predictive model seems to be that of an aligned, axisymmetric field with significant quadrupole and octupole terms.

  3. Abundance variations in solar energetic particles

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Reames, D. V.; Von Rosenvinge, T. T.

    1991-01-01

    Abundance variations are examined in a large number of events including smaller nonimpulsive events not previously considered. Whereas a comparison at equal energy per nucleon is appropriate for heavy ions this is not the case when including H. The best representation is either in terms of rigidity or energy per charge depending on the type of event under consideration. For the majority of large events, where particles are primarily accelerated at interplanetary shocks, if abundances relative to H are evaluated at equal energy per charge then abundance ratios are compatible with solar wind values and spectral shapes agree. Furthermore the behavior of H is then compatible with that of other high FIP elements.

  4. Energetic particle acceleration in the heliosphere

    NASA Astrophysics Data System (ADS)

    Fisk, L. A.; Gloeckler, G.

    2012-05-01

    There has been a remarkable discovery in the heliosphere. Ions accelerated in disparate plasma conditions - the quiet solar wind, disturbed conditions downstream from shocks, and throughout the heliosheath - all have the same spectrum, a power law with spectral index of -5 when expressed as a distribution function. An acceleration mechanism has been developed that can account for these observations, a pump mechanism, in which particles are pumped out of a core distribution through a series of compressions and expansions. The derivation of the governing equation of the pump mechanism and some important subtleties in the derivation are discussed.

  5. Studies of modern and ancient solar energetic particles.

    NASA Astrophysics Data System (ADS)

    Reedy, R.

    1998-12-01

    Modern solar energetic particles (SEPs) have been studied for about 50 years by satellites and ground-based observations. These measurements indicate much about the nature of SEPs but cover too short a period to quantify the probabilities of very large solar particle events. Many SEPs have high enough energies to make nuclides in material in which they interact. Radionuclides measured in lunar samples have been used to extend the record about SEPs back several million years. Some new measurements of modern SEPs during the last solar cycle and new results for nuclides made by SEPS in lunar samples are presented and their implications discussed. Both the modern and ancient records need to be improved, and methods to get a better understanding of solar energetic particles discussed. The fluxes of SEPs during the last million years show an increasing trend when averaged over shorter radionuclide half-lives.

  6. Erosion tests of materials by energetic particle beams

    SciTech Connect

    Schechter, D.E.; Tsai, C.C.; Sluss, F.; Becraft, W.R.; Hoffman, D.J.

    1985-01-01

    The internal components of magnetic fusion devices must withstand erosion from and high heat flux of energetic plasma particles. The selection of materials for the construction of these components is important to minimize contamination of the plasma. In order to study various materials' comparative resistance to erosion by energetic particles and their ability to withstand high heat flux, water-cooled copper swirl tubes coated or armored with various materials were subjected to bombardment by hydrogen and helium particle beams. Materials tested were graphite, titanium carbide (TiC), chromium, nickel, copper, silver, gold, and aluminum. Details of the experimental arrangement and methods of application or attachment of the materials to the copper swirl tubes are presented. Results including survivability and mass losses are discussed.

  7. Space Weather Research in Greece: The Solar Energetic Particle Perspective

    NASA Astrophysics Data System (ADS)

    Malandraki, Olga E.

    2015-03-01

    Space Weather Research carried out in the National Observatory of Athens (NOA), within the SEPServer and COMESEP projects under the Seventh Framework Programme (FP7-SPACE) of the European Union (EU) is presented. Results and services that these projects provide to the whole scientific community as well as stakeholders are underlined. NOA strongly contributes in terms of crucial Solar Energetic Particle (SEP) dataset provided, data analysis and SEP catalogue items provided as well as comparative results of the various components of the project server, greatly facilitating the investigation of SEPs and their origin. SEP research highlights carried out at NOA are also presented, used to test and validate the particle SEP model developed and incorporated within the SEP forecasting tools of the COronal Mass Ejections and Solar Energetic Particles (COMESEP) Space Weather Alert System, i.e. the First European Alert System for geomagnetic storms and SEP radiation hazards.

  8. Energetic Particle Pressure at Interplanetary Shocks: STEREO-A Observations

    NASA Astrophysics Data System (ADS)

    Lario, D.; Decker, R. B.; Roelof, E. C.; Viñas, A.-F.

    2015-11-01

    We study periods of elevated energetic particle intensities observed by STEREO-A when the partial pressure exerted by energetic (≥83 keV) protons (PEP) is larger than the pressure exerted by the interplanetary magnetic field (PB). In the majority of cases, these periods are associated with the passage of interplanetary shocks. Periods when PEP exceeds PB by more than one order of magnitude are observed in the upstream region of fast interplanetary shocks where depressed magnetic field regions coincide with increases of energetic particle intensities. When solar wind parameters are available, PEP also exceeds the pressure exerted by the solar wind thermal population (PTH). Prolonged periods (>12 hr) with both PEP > PB and PEP > PTH may also occur when energetic particles accelerated by an approaching shock encounter a region well upstream of the shock characterized by low magnetic field magnitude and tenuous solar wind density. Quasi-exponential increases of the sum PSUM = PB + PTH + PEP are observed in the immediate upstream region of the shocks regardless of individual changes in PEP, PB, and PTH, indicating a coupling between PEP and the pressure of the background medium characterized by PB and PTH. The quasi-exponential increase of PSUM implies a radial gradient ∂PSUM/∂r > 0 that is quasi-stationary in the shock frame and results in an outward force applied to the plasma upstream of the shock. This force can be maintained by the mobile energetic particles streaming upstream of the shocks that, in the most intense events, drive electric currents able to generate diamagnetic cavities and depressed solar wind density regions.

  9. Energetic Particles at High Latitudes of the Heliosphere

    SciTech Connect

    Zhang Ming

    2004-09-15

    Ulysses has by now made two complete out-of-ecliptic orbits around the sun. The first encounter of the solar poles occurred in 1994-1995, when the sun was near the minimum of its activity cycle, while the second one was in 2000-2001, when the sun was at solar maximum. To our surprise, energetic particles of all origins at high latitude are not much different from those we observe near the ecliptic for at least these two phases of solar cycle. The latitude gradients of galactic and anomalous cosmic rays are positive but small at the 1994-1995 solar minimum and almost zero at the 2000-2001 solar maximum, while temporal solar cycle variation dominates their flux variation at all latitudes. Solar energetic particles from all large gradual events can be seen at both Ulysses and Earth no matter how large their spatial separations from the solar event are, and the particle flux often reaches a uniform level in the entire inner heliosphere within a few days after event onset and remains so throughout the decay phase that can sometimes last over a month. Energetic particles accelerated by low-latitude CIRs can appear at high latitudes, far beyond the latitudinal range of CIRs. All these observations suggest that latitudinal transport of energetic particles is quite easy. In addition, because the average magnetic field is radial at the pole, The Ulysses observations indicate that parallel diffusion and drift in the radial direction need to be reduced at the poles relative to their equatorial values. To achieve such behaviors of particle transport, the heliospheric magnetic field needs a significant latitudinal component at the poles. A non-zero latitudinal magnetic field component can be produced by latitudinal motion of the magnetic field line in solar corona, which can be in form of either random walk suggested by Jokipii or large scale systematic motion suggested by Fisk.

  10. Energetic helium particles trapped in the magnetosphere

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  11. COSTEP: A comprehensive suprathermal and energetic particle analyzer for SOHO

    NASA Technical Reports Server (NTRS)

    Kunow, Horst; Fischer, Harald; Green, Guenter; Mueller-Mellin, Reinhold; Wibberenz, Gerd; Holweger, Hartmut; Evenson, Paul; Meyer, Jean-Paul; Hasebe, Nabuyuki; Vonrosenvinge, Tycho

    1988-01-01

    The group of instruments involved in the COSTEP (comprehensive suprathermal and energetic particle analyzer) project are described. Three sensors, the LION (low energy ion and electron) instrument, the MEICA (medium energy ion composition analyzer) and the EPHIN (electron proton helium instrument) are described. They are designed to analyze particle emissions from the sun over a wide range of species (electrons through iron) and energies (60 KeV/particle to 500 MeV/nucleon). The data collected is used in studying solar and space plasma physics.

  12. The acceleration and propagation of solar flare energetic particles

    NASA Technical Reports Server (NTRS)

    Forman, M. A.; Ramaty, R.; Zweibel, E. G.

    1986-01-01

    A review of the most pertinent data on solar energetic particles is presented, and the implications of the data are discussed, taking into account radio emissions, hard X-rays, gamma rays, energy spectra and electron-proton correlations, chemical compositions, and isotopic and ionic compositions. The mechanisms of solar flare particle acceleration are considered along with solar flare particle spectra in interplanetary space. Attention is given to stochastic acceleration, shock acceleration, acceleration in direct electric fields, the mean free paths of solar electrons and protons in interplanetary space, and an illustration of the probable effect of adiabatic deceleration on the spectra of solar flare ions at the time of maximum.

  13. Energetic Particle Instrumentation for Future Space Physics Missions

    NASA Astrophysics Data System (ADS)

    Perry, C. H.; Griffin, D. K.; Dunlop, M. W.; Davies, J. A.; Hapgood, M. A.

    2009-04-01

    Collisionless plasmas frequently exhibit strong fluxes of electrons and ions at energies well above the mean plasma energy. These suprathermal particles play an important role in the identification and interpretation of the fundamental properties and physical processes within space plasmas. Investigations of these energetic populations require both good angular and temporal resolution measurements. Large geometric factors and fast electronics are vital to ensure adequate sampling of the tail of the particle distribution. We present the status of the energetic particle instrument development activity that is currently underway at the Rutherford Appleton Laboratory. This is in preparation for both the proposed HEP instrument for Cross-Scale mission, which is currently undergoing assessment for the ESA's Cosmic Vision programme, and the IEPS instrument for the Chinese KuaFu mission. The activities are based on the heritage of instruments already successfully flown on the NASA/Polar and ESA/Cluster spacecraft. The design consists of a simple ‘pin-hole' aperture and segmented silicon solid state detector array capable of measuring energetic particle distributions in the range 30-1000 keV. Key features of the activities include the development of 1) a modular mechanical design that can easily support different spacecraft accommodation constraints and scientific requirements, 2) combined detector configurations for ions and electrons, and 3) multi-channel hybrid ASICs for the sensor electronics which is crucial for low mass and power.

  14. The Solar Energetic Particle Event of 14 December 2006

    NASA Astrophysics Data System (ADS)

    von Rosenvinge, T. T.; Richardson, I. G.; Reames, D. V.; Cohen, C. M. S.; Cummings, A. C.; Leske, R. A.; Mewaldt, R. A.; Stone, E. C.; Wiedenbeck, M. E.

    2009-05-01

    The solar energetic particle event on 14 December 2006 was observed by several near-Earth spacecraft including the Advanced Composition Explorer (ACE), STEREO A and B, SOHO and Wind. An interesting feature of this event is a series of unusual fluctuations in the particle intensity that occurred during the first few hours. These fluctuations were observed inside a magnetic cloud that originated in a solar event on 13 December and show both similarities and variations at the different spacecraft. Interestingly, the most striking difference is between observations at the two closely-separated STEREO spacecraft. In particular, large fluctuations in the proton intensity were seen by the High Energy Telescope (HET) on STEREO A, and to a lesser extent at Wind and ACE, but not by the STEREO B HET. We conclude that the differences in intensity-time profiles were caused by anisotropies in the particle distribution and the different viewing directions of the individual particle telescopes. The intensity/anisotropy variations suggest that flux tubes with different particle propagation conditions existed within this magnetic cloud despite the absence of local magnetic field signatures associated with these regions. The intensity fluctuations are similar to those occasionally seen in impulsive particle events. There were also spacecraft-to-spacecraft differences during the onset of the particle event. An initial rapid onset of energetic (> 40 MeV) protons was observed by the STEREO A and B spacecraft outside the magnetic cloud, but not by spacecraft such as SOHO that were already inside the magnetic cloud at this time. The latter spacecraft observed a slower, lower intensity increase. Evidently, energetic proton propagation from the solar event to the vicinity of Earth was inhibited within the magnetic cloud compared to outside.

  15. EPD: the energetic particle instrumentation aboard Solar Orbiter

    NASA Astrophysics Data System (ADS)

    Rodriguez-Pacheco, Javier; Ho, George; Boettcher, Stephan; Martin, Cesar; Sánchez Prieto, Sebastián; Kulkarni, Shrinivasrao; Prieto, Manuel; Panitzsch, Lauri; Gomez-Herrero, Raul; Mason, Glenn M.; Wimmer-Schweingruber, Robert

    2016-07-01

    Solar Orbiter is the first mission of ESA's Cosmic Vision program. Its launch is scheduled for October 2018. After a cruise phase and once in its nominal orbit, it will approach the Sun as close as 0.28 AU. Solar Orbiter has a comprehensive scientific instrumentation that can be divided into two categories: remote sensing and in situ instruments. Within the latter category, the Energetic Particle Detector (EPD) will be responsible for providing data on solar energetic particles (SEP) including its suprathermal population with a temporal and spectral resolutions never achieved in previous missions focused in the inner Heliosphere. We will present the mission instrumentation; its scientific highlights and then describe EPD and its science.

  16. Type 2 radio bursts, interplanetary shocks and energetic particle events

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Stone, R. G.

    1982-01-01

    Using the ISEE-3 radio astronomy experiment data 37 interplanetary (IP) type II bursts have been identified in the period September 1978 to December 1981. These events and the associated phenomena are listed. The events are preceded by intense, soft X ray events with long decay times (LDEs) and type II and/or type IV bursts at meter wavelengths. The meter wavelength type II bursts are usually intense and exhibit herringbone structure. The extension of the herringbone structure into the kilometer wavelength range results in the occurrence of a shock accelerated (SA) event. The majority of the interplanetary type II bursts are associated with energetic particle events. These results support other studies which indicate that energetic solar particles detected at 1 A.U. are generated by shock acceleration. From a preliminary analysis of the available data there appears to be a high correlation with white light coronal transients.

  17. Rocket observations of energetic particles at the geomagnetic equator

    NASA Technical Reports Server (NTRS)

    Smith, L. G.; Houshmand, B.

    1985-01-01

    Energetic particle detectors were included in the payloads of two rockets launched in Peru during the Condor campaign of 1983. These night-time flights reached altitudes of 587 and 535 km, respectively. The pitch-angle distribution is anisotropic with the maximum at 90 deg. Each payload included two solid-state detectors differing in the thickness of the aluminum coating. Comparison of the fluxes measured by the two detectors leads to the conclusion that, on both occasions, the energetic particles are predominantly helium ions. The flux is small below 200 km, increases linearly to 350 km, and then more slowly to apogee. The east-west asymmetry of flux, noted at 200 km in a previous equatorial launch, is not seen at greater altitudes, consistent with the flux profile and the large gyroradius of the ions.

  18. Gyrokinetics Simulation of Energetic Particle Turbulence and Transport

    SciTech Connect

    Diamond, Patrick H.

    2011-09-21

    Progress in research during this year elucidated the physics of precession resonance and its interaction with radial scattering to form phase space density granulations. Momentum theorems for drift wave-zonal flow systems involving precession resonance were derived. These are directly generalizable to energetic particle modes. A novel nonlinear, subcritical growth mechanism was identified, which has now been verified by simulation. These results strengthen the foundation of our understanding of transport in burning plasmas

  19. Energetic particle acceleration at corotating interaction regions: Ulysses results

    SciTech Connect

    Desai, M.I.; Marsden, R.G.; Sanderson, T.R.; Gosling, J.T.

    1997-07-01

    We present here statistical properties of energetic ions (tilde 1 MeV) accelerated by corotating interaction regions observed at the Ulysses spacecraft. We have correlated the tilde 1 MeV proton intensity measured near the trailing edges of the interaction regions with their compression ratio. We interpret our results in terms of the plasma conditions experienced at Ulysses and identify a likely source of the low energy seed particles accelerated at the interaction regions.

  20. Kinetic theory of geomagnetic pulsations: I. Internal excitations by energetic particles

    SciTech Connect

    Chen, Liu . Plasma Physics Lab. Princeton Univ., NJ . Dept. of Astrophysical Sciences); Hasegawa, Akira )

    1990-05-01

    Motivated by recent satellite observations, we have carried out a comprehensive theoretical analysis on the generation of hydromagnetic Alfven waves in a realistic magnetospheric plasma environment consisting of a core and an energetic components. Our theoretical formulation employs the gyrokinetic equations and, thus, retains nonuniform plasma equilibria, anisotropy, finite Larmor radii, magnetic trapping as well as wave-particle interactions. A set of coupled equations for transverse and compressional magnetic perturbations is derived and analyzed for its stabilities assuming interchange stable equilibrium distribution functions. Our findings are compressional and tranverse shear Alfven oscillations are generally coupled in realistic plasmas. In the decoupled limit, for the compressional wave branch, one recovers the drift-mirror instability due to the Landau resonances and {tau} {equivalent to} 1 + 4 {pi}({partial derivative}P{sub {perpendicular}}/B{partial derivative}B) < 0. Here, P{sub {perpendicular}} = P{sub {perpendicular}}({psi},B) is the perpendicular pressure and {psi} is the magnetic flux function. For the decoupled transverse shear Alfven branch, one obtains the drift Alfven ballooning instability due to the Landau resonances and free energy of the pressure gradient for {tau} > 0. For both branches, the most unstable modes have antisymmetric structures and propagate in the diamagnetic drift direction of the energetic ions. Finite coupling can be shown to further enhance the drift Alfven ballooning instabilities. Thus, we conclude that for {tau} {ge} 0, the coupled drift Alfven ballooning-mirror instability constitutes an important internal generating mechanism of geomagnetic pulsations. The various predicted features of this instability are also found to be consistent with satellite observations.

  1. Kinetic theory of geomagnetic pulsations 1. Internal excitations by energetic particles

    SciTech Connect

    Liu Chen ); Hasegawa, Akira )

    1991-02-01

    Motivated by recent satellite observations. the authors have carried out a comprehensive theoretical analysis on the generation of hydromagnetic Alfven waves in a realistic magnetospheric plasma environment consisting of a core ({approximately}100 eV) component and an energetic ({approximately}10 keV) component. The theoretical formulation employs the gyrokinetic equations and, thus, retains anisotropy, finite Larmor radii, magnetic trapping, and wave-particle interactions in addition to nonuniform plasma equilibria. A set of coupled equations for transverse and compressional magnetic perturbations is derived and analyzed for its stabilities assuming equilibrium distribution functions which are interchange stable. The findings are as follows: (1) compressional and transverse shear Alfven oscillations are generally coupled in realistic plasmas; (2) in the decoupled limit, for the compressional wave branch, one recovers the drift mirror instability due to the Landau resonances and {tau}{triple bond} 1 + 4{pi}({partial derivative}P{sub {perpendicular}}/B{partial derivative}B) < 0; here, P{sub {perpendicular}}=P{sub {perpendicular}}({psi},B) is the perpendicular pressure and {psi} is the magnetic flux function; (3) for the decoupled transverse shear Alfven branch, one obtains the drift Alfven ballooning instability due to the Landau resonances and free energy of the pressure gradient for {tau} > 0; (4) for both branches, the most unstable modes have antisymmetric structures and propagate in the diamagnetic drift direction of the energetic ions; and (5) finite coupling can be shown to further enhance the drift Alfven ballooning instabilities. Thus they conclude that for {tau}{ge}0, the coupled drift Alfven ballooning mirror instability constitutes an important internal generating mechanism of geomagnetic pulsations. The various predicted features of this instability are consistent with satellite observations.

  2. Cancellation of drift kinetic effects between thermal and energetic particles on the resistive wall mode stabilization

    NASA Astrophysics Data System (ADS)

    Guo, S. C.; Liu, Y. Q.; Xu, X. Y.; Wang, Z. R.

    2016-07-01

    Drift kinetic stabilization of the resistive wall mode (RWM) is computationally investigated using MHD-kinetic hybrid code MARS-K following the non-perturbative approach (Liu et al 2008 Phys. Plasmas 15 112503), for both reversed field pinch (RFP) and tokamak plasmas. Toroidal precessional drift resonance effects from trapped energetic ions (EIs) and various kinetic resonances between the mode and the guiding center drift motions of thermal particles are included into the self-consistent toroidal computations. The results show cancellation effects of the drift kinetic damping on the RWM between the thermal particles and EIs contributions, in both RFP and tokamak plasmas, even though each species alone can provide damping and stabilize RWM instability by respective kinetic resonances. The degree of cancellation generally depends on the EIs equilibrium distribution, the particle birth energy, as well as the toroidal flow speed of the plasma.

  3. Los Alamos energetic particle sensor systems at geostationary orbit

    SciTech Connect

    Baker, D.N.; Aiello, W.; Asbridge, J.R.; Belian, R.D.; Higbie, P.R.; Klebesadel, R.W.; Laros, J.G.; Tech, E.R.

    1985-01-01

    The Los Alamos National Laboratory has provided energetic particle sensors for a variety of spacecraft at the geostationary orbit (36,000 km altitude). The sensor system called the Charged Particle Analyzer (CPA) consists of four separate subsystems. The LoE and HiE subsystems measure electrons in the energy ranges 30 to 300 keV and 200 to 2000 keV, respectively. The LoP and HiP subsystems measure ions in the ranges 100 to 600 keV and 0.40 to 150 MeV, respectively. A separate sensor system called the spectrometer for energetic electrons (SEE) measures very high-energy electrons (2 to 15 MeV) using advanced scintillator design. In this paper we describe the relationship of operational anomalies and spacecraft upsets to the directly measured energetic particle environments at 6.6 R/sub E/. We also compare and contrast the CPA and SEE instrument design characteristics with the next generation of Los Alamos instruments to be flown at geostationary altitudes.

  4. Predictions of energetic particle radiation in the close Martian environment

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, Susan M. P.; Dryer, M.; Fry, C. D.; Sun, W.; Lario, D.; Deehr, C. S.; Sanahuja, B.; Afonin, V. A.; Verigin, M. I.; Kotova, G. A.

    2005-03-01

    Intense, prolonged solar flare activity during March 1989 was used to provide a retrospective scenario for predictions of associated interplanetary shocks and accompanying particle radiation at planet Mars. Shocks from five major flares were simulated to hit both the Earth and Mars during the interval 9-23 March 1989. The simulated scenario was provided by the Hakamada-Akasofu-Fry version 2 (HAFv.2) solar wind model. Since part of the generally required inputs for the model (specifically metric radio Type II coronal shock speeds) were not available, the shock speeds were iteratively determined via a "calibration" that uses limited IMP 8 particle and sudden storm commencement (SSC) data as proxies for shock arrival at the Earth. The shocks from four major solar flares were, thereby, found to arrive at Mars at times that are appropriate to explain solar energetic particle (SEP) and energetic storm particle (ESP) events recorded in situ by the particle radiation detector experiments Solar Low Energy Detector (SLED) and Low Energy Telescope (LET) aboard Phobos-2. Supporting measurements were provided by the magnetometer (MAGMA) and plasma spectrometer (TAUS) experiments. A gap in the spacecraft records occurred at the simulated time of arrival of the fifth flare-associated shock. There were some uncertainties attending the selection of certain of the events deemed to be "parent" flares. Such uncertainty can be expected in view of the incomplete set of energetic particle, plasma, and magnetic field measurements made at relevant times at both the Earth and Mars (the latter planet was then located at a distance of 1.6 AU, at about 78° east of the Sun-Earth line). Use of the HAFv.2 solar wind model affords a 4-day lead time between predicted and measured space weather events at Mars, with an error of approximately ±12 hours. Solar radiation events of the magnitude studied occur often enough to warrant consideration in the design of both manned and unmanned expeditions to

  5. Gyrokinetic simulations of mesoscale energetic particle-driven Alfvenic turbulent transport embedded in microturbulence

    SciTech Connect

    Bass, E. M.; Waltz, R. E.

    2010-11-15

    Energetic particle (EP) transport from local high-n toroidal Alfven eigenmodes (TAEs) and energetic particle modes (EPMs) is simulated with a gyrokinetic code. Linear and nonlinear simulations have identified a parameter range where the longwave TAE and EPM are unstable alongside the well-known ion-temperature-gradient (ITG) and trapped-electron-mode (TEM) instabilities. A new eigenvalue solver in GYRO facilitates this mode identification. States of nonlinearly saturated local TAE/EPM turbulent intensity are identified, showing a 'soft' transport threshold for enhanced energetic particle transport against the TAE/EPM drive from the EP pressure gradient. The very long-wavelength (mesoscale) TAE/EPM transport is saturated partially by nonlinear interaction with microturbulent ITG/TEM-driven zonal flows. Fixed-gradient-length, nonlinearly saturated states are accessible over a relatively narrow range of EP pressure gradient. Within this range, and in the local limit employed, TAE/EPM-driven transport more closely resembles drift-wave microturbulent transport than 'stiff' ideal MHD transport with a clamped critical total pressure gradient. At a higher, critical EP pressure gradient, fixed-gradient nonlinear saturation fails: EP transport increases without limit and background transport decreases. Presumably saturation is then obtained by relaxation of the EP pressure gradient to near this critical EP pressure gradient. If the background plasma gradients driving the ITG/TEM turbulence and zonal flows are weakened, the critical gradient collapses to the TAE/EPM linear stability threshold. Even at the critical EP pressure gradient there is no evidence that TAE/EPM instability significantly increases transport in the background plasma channels.

  6. Energetic particle environment in near-Earth orbit.

    PubMed

    Klecker, B

    1996-01-01

    The hazard of exposure to high doses of ionizing radiation is one of the primary concerns of extended manned space missions and a continuous threat for the numerous spacecraft in operation today. In the near-Earth environment the main sources of radiation are solar energetic particles (SEP), galactic cosmic rays (GCR), and geomagnetically trapped particles, predominantly protons and electrons. The intensity of the SEP and GCR source depends primarily on the phase of the solar cycle. Due to the shielding effect of the Earth's magnetic field, the observed intensity of SEP and GCR particles in a near-Earth orbit will also depend on the orbital parameters altitude and inclination. The magnetospheric source strength depends also on these orbital parameters because they determine the frequency and location of radiation belt passes. In this paper an overview of the various sources of radiation in the near-Earth orbit will be given and first results obtained with the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) will be discussed. SAMPEX was launched on 3 July 1992 into a near polar (inclination 82 degrees) low altitude (510 x 675 km) orbit. The SAMPEX payload contains four separate instruments of high sensitivity covering the energy range 0.5 to several hundred MeV/nucleon for ions and 0.4 to 30 MeV for electrons. This low altitude polar orbit with zenith-oriented instrumentation provides a new opportunity for a systematic study of the near-Earth energetic particle environment. PMID:11540369

  7. Optimizing Stellarators for Energetic Particle Confinement using BEAMS3D

    NASA Astrophysics Data System (ADS)

    Bolgert, Peter; Drevlak, Michael; Lazerson, Sam; Gates, David; White, Roscoe

    2015-11-01

    Energetic particle (EP) loss has been called the ``Achilles heel of stellarators,'' (Helander, Rep. Prog. Phys. 77 087001 (2014)) and there is a great need for magnetic configurations with improved EP confinement. In this study we utilize a newly developed capability of the stellarator optimization code STELLOPT: the ability to optimize EP confinement via an interface with guiding center code BEAMS3D (McMillan et al., Plasma Phys. Control. Fusion 56, 095019 (2014)). Using this new tool, optimizations of the W7-X experiment and ARIES-CS reactor are performed where the EP loss fraction is one of many target functions to be minimized. In W7-X, we simulate the experimental NBI system using realistic beam geometry and beam deposition physics. The goal is to find configurations with improved neutral beam deposition and energetic particle confinement. These calculations are compared to previous studies of W7-X NBI deposition. In ARIES-CS, we launch 3.5 MeV alpha particles from a near-axis flux surface using a uniform grid in toroidal and poloidal angle. As these particles are born from D-T reactions, we consider an isotropic distribution in velocity space. This research is supported by DoE Contract Number DE-AC02-09CH11466.

  8. Irregular Magnetic Fields and Energetic Particles near the Termination Shock

    SciTech Connect

    Giacalone, J.; Jokipii, J. R.

    2004-09-15

    The physics of magnetic field-line meandering and the associated energetic-particle transport in the outer heliosphere is discussed. We assume that the heliospheric magnetic field, which is frozen into the solar-wind plasma, is composed of both an average and random component. The power in the random component is dominated by spatial scales that are very large (by a few orders of magnitude) compared to the shock thickness. The results from recent numerical simulations are presented. They reveal a number of characteristics which may be related to recent Voyager 1 observations of energetic particles and fields. For instance, low-energy (tens of keV) particles are seen well upstream of the shock that also have large pitch-angle anisotropies. Furthermore, low-energy particles are readily accelerated by the shock, even though their mean-free paths are very large compared to their gyroradii. When averaging over the entire system, the downstream spectra are qualitatively consistent with the theory of diffusive shock acceleration.

  9. Energetic Particle Measurements on Mars and in Lunar Orbit

    NASA Astrophysics Data System (ADS)

    Zeitlin, C. J.; Hassler, D.; Schwadron, N.; Spence, H. E.; Wimmer-Schweingruber, R. F.; Appel, J. K.; Boehm, E.; Boettcher, S. S.; Brinza, D. E.; Burmeister, S.; Ehresmann, B.; Guo, J.; Kohler, J.; Lohf, H.; Martin-Garcia, C.; Posner, A.; Rafkin, S. C.; weigle, G., II; Martín-Torres, J.; Zorzano, M. P.

    2014-12-01

    The Radiation Assessment Detector (RAD) aboard the Curiosity rover has been making measurements of energetic particles on the surface of Mars since the rover landed in August 2012. RAD also acquired data for most of the cruise to Mars, from Dec. 2011 through July 2012. In both cruise and on the surface, RAD is under considerable shielding, averaging 22 g cm-2 of CO2 during the surface mission, and ~ 16 g cm-2 during cruise. The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the LRO spacecraft in lunar orbit has been making measurements since mid-2009. CRaTER contains three sets of detectors, of which one is unshielded, one is under 6 g cm-2 of tissue-equivalent plastic (TEP) shielding, and one is under 9 g cm-2 of TEP. Taken together, the two experiments provide a wealth of data concerning the effects of shielding on Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). Comparison of data from the two instruments is complicated by their different locations in the heliosphere, which at most times causes them to be magnetically connected to different regions on the Sun. Variability of the atmospheric shielding above RAD, which is both diurnal and seasonal, also influences the comparison. During solar quiet time, when the energetic particle flux is due to GCRs, many similarities - and some small but significant differences - are seen in detailed time series data. In contrast, during SEP events, both the shielding and location disparities cause large differences in the measured particle fluxes.

  10. Solar Flares, Type III Radio Bursts, CMEs, and Energetic Particles

    NASA Technical Reports Server (NTRS)

    Cane, H. V.

    2004-01-01

    Despite the fact that it has been well known since the earliest observations that solar energetic particle events are well associated with solar flares it is often considered that the association is not physically significant. Instead, in large events, the particles are considered to be only accelerated at a shock driven by the coronal mass ejection (CME) that is also always present. If particles are accelerated in the associated flare, it is claimed that such particles do not find access to open field lines and therefore do not escape from the low corona. However recent work has established that long lasting type III radio bursts extending to low frequencies are associated with all prompt solar particle events. Such bursts establish the presence of open field lines. Furthermore, tracing the radio bursts to the lowest frequencies, generated near the observer, shows that the radio producing electrons gain access to a region of large angular extent. It is likely that the electrons undergo cross field transport and it seems reasonable that ions do also. Such observations indicate that particle propagation in the inner heliosphere is not yet fully understood. They also imply that the contribution of flare particles in major particle events needs to be properly addressed.

  11. Simulations of Energetic Particles Interacting with Dynamical Magnetic Turbulence

    NASA Astrophysics Data System (ADS)

    Hussein, M.; Shalchi, A.

    2016-02-01

    We explore the transport of energetic particles in interplanetary space by using test-particle simulations. In previous work such simulations have been performed by using either magnetostatic turbulence or undamped propagating plasma waves. In the current paper we simulate for the first time particle transport in dynamical turbulence. To do so we employ two models, namely the damping model of dynamical turbulence and the random sweeping model. We compute parallel and perpendicular diffusion coefficients and compare our numerical findings with solar wind observations. We show that good agreement can be found between simulations and the Palmer consensus range for both dynamical turbulence models if the ratio of turbulent magnetic field and mean field is δB/B0 = 0.5.

  12. Energetic particle studies at Mars by SLED on PHOBOS 2

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Afonin, V. V.; Gringauz, K. I.; Kecskemety, K.; Keppler, E.; Kirsch, E.; Richter, A.; Rusznyak, P.; Schwingenschuh, K.; O'Sullivan, D.

    1992-09-01

    Data recorded by the SLED instruments on Phobos 2 while it was in the first four elliptical orbits and during 114 circular orbits about Mars (February-March, 1989) are presented. Data obtained while in close elliptical orbits around the planet display evidence of energy-related particle shadowing by the body of Mars; this effect was also sometimes observed in circular orbits at an altitude of 6330 km above the planet. Possible explanations of this phenomenon include the presence of quasi-trapped radiation of Mars and the detected propagation of accelerated particles along the boundary of the magnetopause from the dayside to the nightside of the planet. In circular orbits, many significant flux enhancement events, in the range 30-200 keV, were detected adjacent to the bow shock, indicating that the spacecraft traversed strongly anisotropic jets of energetic particles, which are suggested to contain O(+) ions.

  13. Nightside energetic particle decreases at the synchronous orbit

    NASA Technical Reports Server (NTRS)

    Bogott, F. H.

    1973-01-01

    More than 100 cases of major decreases of proton and electron fluxes at the synchronous orbit have been observed and interpreted as a movement of the energetic particle trapping boundary earthward of 6.6 earth radii before the substorm expansion phase. These events are observed only between 1700 and 0800 LT and are consistent with the existence of a westward magnetospheric electric field of a few tenths of a millivolt per meter before substorm expansion. Most substorm particle events seen on the nightside do not exhibit this behavior, presumably because the trapping boundary moves inside 6.6 earth radii only during major events. Such events show evidence of particle acceleration, which probably was concentrated at higher L values, near the instantaneous location of the trapping boundary.

  14. Ionization of the atmosphere caused by energetic particles

    NASA Astrophysics Data System (ADS)

    Maik Wissing, Jan; Kallenrode, May-Britt

    Energetic particles from different sources are precipitating into the atmosphere, causing ionization and different chemical follow-ups. Focussing on low and mid-energies, this presentation will concentrate on the solar and magnetospheric particle spectrum, representing the particle forcing from the thermosphere down to the tropopause. While the precipitation of solar particles can be described in simple patterns, the magnetospheric precipitation is intensively modulated by the geomagnetic field, varying with latitude, longitude, geomagnetic disturbance, and MLT, ending up in a fluctuating auroral oval. Modeling the resulting ionization consequently is confronted with numerous challenges, ranging from sparse measurements (in-situ measuring satellites vs. global coverage), contaminated detectors, strong flux variation in space and time and finally the conversion of flux measurements into (3D) ionization profiles. This presentation will give an overview of the general setup, discuss main aspects in modeling particle precipitation and present some recent advances with the help of the Atmospheric Ionization Module OSnabrueck (AIMOS). AIMOS is based on a Geant4 Monte-Carlo Simulation for particle interactions with the atmosphere and in-situ particle measurements from the POES and GOES satellites.

  15. Tracing of energetic particles in the vicinity of Titan

    NASA Astrophysics Data System (ADS)

    Regoli, Leonardo; Jones, Geraint; Krupp, Norbert; Coates, Andrew; Roussos, Elias; Kotova, Anna; Feyerabend, Moritz

    2014-05-01

    We present results from the application of a particle tracing software specifically developed to study the interaction of Titan with the surrounding magnetospheric plasma. By combining the output of hybrid plasma code simulations with the tracing software itself, we aim to further study the different ionization processes occurring at Titan with special emphasis on the role played by energetic ions and electrons. The tracing software is used to simulate the trajectories of particles entering the Titan environment from different positions with energy ranges similar to those observed by the Cassini MIMI/LEMMS detector and with different pitch angle distributions and thus be able to estimate the amount of particles that interact with the moon's atmosphere and those that escape the system due to magnetic and electric field perturbations or charge-exchange with the high-altitude exosphere. Additionally, a comparison of the results obtained with the observational data available from the CAPS, and MIMI instruments allows us to validate the results of the tracing software for those regions of Titan not sampled by Cassini at a given flyby. For this initial study, we show the first maps of allowed energetic electron and ion access (as a function of energy) at Titan's exobase, when magnetic and electric field disturbances in a reference Titan interaction region are considered. Similar maps will be used as input for ionization and energy deposition calculation in future steps of this project.

  16. The Solar Energetic Particle experiment on MAVEN: First Results

    NASA Astrophysics Data System (ADS)

    Larsen, Davin; Lillis, Robert J.; Rahmati, Ali; Dunn, Patrick; Cravens, Tom; Curtis, David; Hatch, Ken; Robinson, Miles; Glaser, David; Halekas, Jasper; Jakosky, Bruce; Luhmann, Janet; McFadden, James P.; Connerney, Jack

    2015-04-01

    The Solar Energetic Particle (SEP) instrument arrived at Mars onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission on September 22, 2014. In order for MAVEN to determine the role that loss of volatiles to space has played through time, solar energy input to the Martian system must be characterized. An important (if infrequent and episodic) portion of this input is in the form of solar energetic particle (SEP) events. Understanding the relationship between SEP events and atmospheric escape is crucial to understanding the climate history of Mars. The SEP instrument characterizes such events at Mars by measuring energetic protons and electrons in the energy range absorbed by the upper atmosphere. Additionally, under certain conditions, SEP directly measures the flux of escaping Oxygen that has been picked up by the Solar Wind and can provide limits on this important escape mechanism [1]. The implications of the model comparison with SEP data for the escape of neutral oxygen from Mars will be discussed. SEP takes much of its heritage from the Solid State Telescope (SST) on the THEMIS mission, consisting of 2 orthogonal dual double-ended solid-state telescopes. Proton spectra from 25 keV to 6 MeV and electron spectra from 25 keV to 1 MeV will be collected in 4 look directions at 3 measurement cadences over MAVEN’s 4.5-hour elliptical orbit: 32s far from the planet, 8s between 300 and 800 km altitude and 2s below 300 km. SEP measures particle fluxes from ~20 to ~107 cm-2 s -1 sr-1. We will present results from the first 5 months of the MAVEN science mission.References: [1] Rahmati A. et al. (2014) GRL 41(14) , 4812-481

  17. Energetic Geodesic Acoustic Modes Associated with Two-Stream-like Instabilities in Tokamak Plasmas.

    PubMed

    Qu, Z S; Hole, M J; Fitzgerald, M

    2016-03-01

    An unstable branch of the energetic geodesic acoustic mode (EGAM) is found using fluid theory with fast ions characterized by their narrow width in energy distribution and collective transit along field lines. This mode, with a frequency much lower than the thermal GAM frequency ω_{GAM}, is now confirmed as a new type of unstable EGAM: a reactive instability similar to the two-stream instability. The mode can have a very small fast ion density threshold when the fast ion transit frequency is smaller than ω_{GAM}, consistent with the onset of the mode right after the turn-on of the beam in DIII-D experiments. The transition of this reactive EGAM to the velocity gradient driven EGAM is also discussed. PMID:26991183

  18. Precision Measurements of Solar Energetic Particle Elemental Composition

    NASA Technical Reports Server (NTRS)

    Breneman, H.; Stone, E. C.

    1985-01-01

    Data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spaceraft were used to determined, solar energetic particle abundances or upper limits for all elements with Z 30 from a combined set of 10 solar flares during the 1977 to 1982 time period. Statistically meaningful abundances were determined for several rare elements including P, C1, K, Ti and Mn, while the precision of the mean abundances for the more abundant elements was proved. When compared to solar photospheric spectroscopic abundances, these new SEP abundances more clearly exhibit the step-function dependence on first ionization potential previously reported.

  19. Precision measurements of solar energetic particle elemental composition

    NASA Technical Reports Server (NTRS)

    Breneman, H.; Stone, E. C.

    1985-01-01

    Using data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spacecraft, solar energetic particle abundances or upper limits for all elements with 3 = Z = 30 from a combined set of 10 solar flares during the 1977 to 1982 time period were determined. Statistically meaningful abundances have been determined for the first time for several rare elements including P, Cl, K, Ti and Mn, while the precision of the mean abundances for the more abundant elements has been improved by typically a factor of approximately 3 over previously reported values.

  20. Turbulence Evolution and Shock Acceleration of Solar Energetic Particles

    NASA Technical Reports Server (NTRS)

    Chee, Ng K.

    2007-01-01

    We model the effects of self-excitation/damping and shock transmission of Alfven waves on solar-energetic-particle (SEP) acceleration at a coronal-mass-ejection (CME) driven parallel shock. SEP-excited outward upstream waves speedily bootstrap acceleration. Shock transmission further raises the SEP-excited wave intensities at high wavenumbers but lowers them at low wavenumbers through wavenumber shift. Downstream, SEP excitation of inward waves and damping of outward waves tend to slow acceleration. Nevertheless, > 2000 km/s parallel shocks at approx. 3.5 solar radii can accelerate SEPs to 100 MeV in < 5 minutes.

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  2. Heliospheric Energetic Particles and Galactic Cosmic Ray Modulation

    NASA Astrophysics Data System (ADS)

    Malandraki, Olga

    2015-08-01

    The paper presents an overview of the SH ‘Solar and Heliospheric cosmic rays’ session of the 24th European Cosmic Ray Symposium (ECRS), Kiel, Germany, 2014. It covers the topics of Solar Energetic Particle (SEP) origin, acceleration and transport at the Sun and in the interplanetary medium, also from the aspect of multi-spacecraft observations, as well as the Galactic Cosmic Ray (GCR) short- and long-term variations and the Jovian electron variations in the heliosphere. Relevant instruments and methods presented are also covered by this review. The paper is written from a personal perspective, emphasizing those results that the author found most interesting.

  3. Solar coronal and photospheric abundances from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Breneman, H. H.; Stone, E. C.

    1985-01-01

    Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with Z = 6-30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

  4. Solar Coronal and photospheric abundances from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Breneman, H.; Stone, E. C.

    1985-01-01

    Solar energetic particle (SEP) elemental abundance data from the cosmic ray subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 Z or = 30. It is found that the ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

  5. Solar coronal and photospheric abundances from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Breneman, H.; Stone, E. C.

    1985-01-01

    Solar energetic particle (SEP) elemental abundance data from the Cosmic Ray Subsystem (CRS) aboard the Voyager 1 and 2 spacecraft are used to derive unfractionated coronal and photospheric abundances for elements with 3 = or Z or = 30. The ionic charge-to-mass ratio (Q/M) is the principal organizing parameter for the fractionation of SEPs by acceleration and propagation processes and for flare-to-flare variability, making possible a single-parameter Q/M-dependent correction to the average SEP abundances to obtain unfractionated coronal abundances. A further correction based on first ionization potential allows the determination of unfractionated photospheric abundances.

  6. Initial Time Dependence of Abundances in Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.; Ny, C. K.; Tylka, A. J.

    1999-01-01

    We compare the initial behavior of Fe/O and He/H abundance ratios and their relationship to the evolution of the proton energy spectra in "small" and "large" gradual solar energetic particle (SEP) events. The results are qualitatively consistent with the behavior predicted by the theory of Ng et al. (1999a, b). He/H ratios that initially rise with time are a signature of scattering by non-Kolmogorov Alfven wave spectra generated by intense beams of shock-accelerated protons streaming outward in large gradual SEP events.

  7. Preparation and characterization of energetic materials coated superfine aluminum particles

    NASA Astrophysics Data System (ADS)

    Liu, Songsong; Ye, Mingquan; Han, Aijun; Chen, Xin

    2014-01-01

    This work is devoted to protect the activity of aluminum in solid rocket propellants by means of solvent/non-solvent method in which nitrocellulose (NC) and Double-11 (shortened form of double-base gun propellant, model 11) have been used as coating materials. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the morphology of coated Al particles. Other characterization data of coated and uncoated Al particles, such as infrared absorption spectrum, laser particle size analysis and the active aluminum content were also studied. The thermal behavior of pure and coated aluminum samples have also been studied by simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC). The results indicated that: superfine aluminum particles could be effectively coated with nitrocellulose and Double-11 through a solvent/non-solvent method. The energetic composite particles have core-shell structures and the thickness of the coating film is about 20-50 nm. The active aluminum content of different coated samples was measured by means of oxidation-reduction titration method. The results showed that after being stored in room temperature and under 50% humidity condition for about 4months the active aluminum content of coated Al particles decreased from 99.8 to 95.8% (NC coating) and 99.2% (Double-11 coating) respectively. Double-11 coating layer had a much better protective effect. The TG-DTA and DSC results showed that the energy amount and energy release rate of NC coated and Double-11 coated Al particles were larger than those of the raw Al particles. Double-11 coated Al particles have more significant catalytic effect on the thermal decomposition characters of AP than that of NC coated Al particles. These features accorded with the energy release characteristics of solid propellant.

  8. Observation of Energetic Particles Associated with a CIR Pair

    NASA Astrophysics Data System (ADS)

    Wu, Z.; CHEN, Y.; Li, G.; Liu, Y.; Ebert, R. W.; Desai, M. I.; Mason, G. M.; Guo, F.; Tang, C.

    2012-12-01

    Corotating Interaction Regions (CIRs) are efficient interplanetary particle accelerators in solar minimum. Occasionally, two (or multiple) CIRs may be observed at 1AU with a separation of ~5 days. Under certain circumstances, these CIR pairs can lead to enhanced particle acceleration than a single CIR. In this work, we report, to our knowledge, the first observational evidence of particle acceleration at a CIR pair. This CIR pair occurred in CR2060 (Aug. 14 - Sept. 10, 2007). Observations from STEREO-B (IMPACT/SEPT and IMPACT/LET for energetic ions/electrons and PLASTIC for plasma) showed that the first CIR was between Aug. 24th and Aug. 26th and the second CIR between Aug. 30th and Sep. 2nd. In between the CIR pair, energetic protons reached up to several MeV and energetic electrons up to hundreds of keVs. Both sunward and anti-sunward proton fluxes in the energy range of 4 - 6 MeV were observed, with the sunward (anti-sunward) component dominating in the region closer to the preceding (trailing) CIR. Near the middle of the pair the two components are comparable. The energy spectrum of He ion appears to be harder than that often found at a typical single CIR. These observations are consistent with a scenario where particles are accelerated at two shocks which are magnetically connected. We suggest that such a connection is through large-scale U-shape magnetic field that is detached from the Sun through magnetic reconnection in the upper corona. The presence of counter-streaming solar electrons (~ 200 eV) and the reversal of magnetic field direction between the CIR pair support this scenario. We point out that a system consisting of two shocks connected by a U-shape magnetic field line provides naturally a more efficient particle acceleration site than a single CIR shock. We have also performed a 2-D MHD simulation to help us understanding the above scenario.

  9. Probabilistic Assessment of Risks from Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Adams, James H., Jr.; Dietrich, W. F.; Xapsos, M. A.

    2010-01-01

    Solar energetic particle events pose a radiation hazard for space crews and a risk of harmful radiation effects in spacecraft electronics. To assess these risks, engineers need to know the worst-case environment that they must plan for or design to withstand. Depending on the application, engineers may need to know the instantaneous worst-case environment, the radiation environment that accumulates during one solar particle event or the cumulative worst-case environment for their entire mission. Also, depending on their application, they will need to know this environment at a confidence level which they will specify. We will present a probabilistic model for the peak fluxes, event-integrated fluences and mission-integrated fluences for solar protons and heavy ions. The model will provide these worst-case environments at user-specified confidence levels. Examples of the use of this model will also be shown.

  10. Energetic particle-induced enhancements of stratospheric nitric acid

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1994-01-01

    Inclusion of complete ion chemistry in the calculation of minor species production during energetic particle deposition events leads to significant enhancement in the calculated nitric acid concentration during precipitation. An ionization rate of 1.2 x 10(exp 3)/cu cm/s imposed for 1 day increases HNO3 from 3 x 10(exp 5) to 6 x 10(exp 7)/cu cm at 50 km. With an ionization rate of 600 cu cm/s, the maximum HNO3 is 3 x 10(exp 7)/cu cm. Calculations which neglect negative ions predict the nitric acid will fall during precipitation events. The decay time for converting HNO3 into odd nitrogen and hydrogen is more than 1 day for equinoctial periods at 70 deg latitude. Examination of nitric acid data should yield important information on the magnitude and frequency of charged particle events.

  11. Three-dimensional interplanetary stream magnetism and energetic particle motion

    NASA Technical Reports Server (NTRS)

    Barouch, E.; Burlaga, L. F.

    1976-01-01

    Cosmic rays interact with mesoscale configurations of the interplanetary magnetic field. A technique is presented for calculating such configurations in the inner solar system, which are due to streams and source conditions near the sun, and maps of magnetic field are constructed for some plausible stream and source conditions. One effect of these mesoscale configurations on galactic cosmic rays is shown to be an out-of-the-ecliptic gradient drift sufficient to explain Forbush decreases. The effects on solar energetic particles include small polar drifts due to the field gradients and a possibly large modification of the time-intensity profiles and anisotropy characteristics due to the formation of mirror configurations in space. If a diffusion model is applicable to solar particles, the true diffusion coefficient will be masked by the effects of streams. A conceptual model which incorporates these ideas and those of several other models is presented.

  12. Simulations of Diffusion in Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Pei, C.; Jokipii, J.; Giacalone, J.

    2007-12-01

    New observations by high-sensitivity instruments onboard the ACE spacecraft show that Fe and O may share similar injection profiles close the solar surface, and that diffusion dominates the transport of these particles (Mason et al 2006). Multi-spacecraft observations by Helios and IMP-8 also confirm the spatial diffusion is important (Wibberenz & Cane 2006). The "reservoir" phenomenon or "spatial invariance" states that during the decay phase of individual gradual solar energetic particle events, the intensities measured by different spacecraft are nearly equal, even if these spacecraft are separated by several AU in radius and by 70 degrees in latitude. Results from our multidimensional numerical model, based on Parker's transport equation, with reasonable values of κ\\perp and κ\\| are compared with observations from Ulysses, IMP-8, and ACE. We demonstrate that most of the features of the "reservoir" phenomenon can be reproduced by a transport model which includes drift, energy loss, and spatial diffusion.

  13. Drifting energetic particle bunches observed on ATS 5

    NASA Technical Reports Server (NTRS)

    Bogott, F. H.; Mozer, F. S.

    1974-01-01

    Energetic protons and electrons introduced into the vicinity of the synchronous orbit by geomagnetic substorms and observed on ATS 5 at various local times have been analyzed for velocity dispersion effects associated with their longitudinal drift. Particles with energies between about 30 and 200 keV are shown to be produced simultaneously within tens of minutes at local times between about 0000 and 0400 near 6.6 earth radii during substorm activity. Those with energies not less than approximately 75 keV move in longitude in the direction and with the magnitude expected from gradient B drifts. Lower-energy protons and electrons appear at the satellite sooner than expected from their gradient B drifts, as though the observed particles of such energies were not those originally accelerated but were newly produced from or by the higher-energy drifting component.

  14. Coronal element abundances derived from solar energetic particles

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1994-01-01

    The large gradual solar-energetic-particle (SEP) events, where abundances are commonly measured, are produced when coronal mass ejections (CMEs) drive shock waves through the corona and the interplanetary medium. The shock accelerates particles from the highly-ionized, approximately 1.5 MK, plasma in a manner that depends only weakly upon the Q/A of the ion, except at very high energies. Averaging the approximately 1 MeV/amu abundances over many events compensates for the acceleration effects to produce abundances that appear to correspond directly to those in the coronal source for all observed elements, including H. The resulting abundances reflect the 4 x enhancement of ions with low values of first ionization potential (FIP) arising from ion-neutral fractionation that occurs as the atoms are transported up from the photosphere. A different pattern of fractionation is found for ions that are shock-accelerated from the high speed solar wind emerging from coronal holes.

  15. Perpendicular diffusion of energetic particles in noisy reduced magnetohydrodynamic turbulence

    SciTech Connect

    Shalchi, A.; Hussein, M. E-mail: m_hussein@physics.umanitoba.ca

    2014-10-10

    A model for noisy reduced magnetohydrodynamic turbulence was recently proposed. This model was already used to study the random walk of magnetic field lines. In the current article we use the same model to investigate the diffusion of energetic particles across the mean magnetic field. To compute the perpendicular diffusion coefficient, two analytical theories are used, namely, the Non-Linear Guiding Center theory and the Unified Non-Linear Transport (UNLT) theory. It is shown that the two theories provide different results for the perpendicular diffusion coefficient. We also perform test-particle simulations for the aforementioned turbulence model. We show that only the UNLT theory describes perpendicular transport accurately, confirming that this is a powerful tool in diffusion theory.

  16. Perpendicular diffusion of energetic particles in collisionless plasmas

    SciTech Connect

    Shalchi, A.

    2015-01-15

    A fundamental problem in plasma and astrophysics is the interaction between energetic particles and magnetized plasmas. In the current paper, we focus on particle diffusion across the guide magnetic field. It is shown that the perpendicular diffusion coefficient depends only on the parallel diffusion coefficient and the Kubo number. Therefore, one can find four asymptotic limits depending on the values of these two parameters. These regimes are the quasilinear limit, the Kadomtsev and Pogutse limit, the scaling of Rechester and Rosenbluth, and the scaling found by Zybin and Istomin. In the current article, we focus on the Rechester and Rosenbluth scenario because this was not discovered before in the context of collisionless plasmas. Examples and applications are discussed as well. We show that an energy independent ratio of perpendicular and parallel diffusion coefficients can be found and that this ratio can be very small but also close to unity. This is exactly what one observes in the solar wind.

  17. Finite orbit energetic particle linear response to toroidal Alfven eigenmodes

    SciTech Connect

    Berk, H.L.; Ye, Huanchun . Inst. for Fusion Studies); Breizman, B.N. . Inst. Yadernoj Fiziki)

    1991-07-01

    The linear response of energetic particles to the TAE modes is calculated taking into account their finite orbit excursion from the flux surfaces. The general expression reproduces the previously derived theory for small banana width: when the banana width {triangle}{sub b} is much larger than the mode thickness {triangle}{sub m}, we obtain a new compact expression for the linear power transfer. When {triangle}{sub m}/{triangle}{sub b} {much lt} 1, the banana orbit effect reduces the power transfer by a factor of {triangle}{sub m}/{triangle}{sub b} from that predicted by the narrow orbit theory. A comparison is made of the contribution to the TAE growth rate of energetic particles with a slowing-down distribution arising from an isotropic source, and a balance-injected beam source when the source speed is close to the Alfven speed. For the same stored energy density, the contribution from the principal resonances ({vert bar}{upsilon}{sub {parallel}}{vert bar} = {upsilon}{sub A} is substantially enhanced in the beam case compared to the isotropic case, while the contribution at the higher sidebands ({vert bar}{upsilon}{sub {parallel}}{vert bar}) = {upsilon}{sub A}/(2{ell} {minus} 1) with {ell} {ge} 2) is substantially reduced. 10 refs.

  18. Research Activities on MHD and Energetic Particle Physics in KSTAR

    NASA Astrophysics Data System (ADS)

    Park, Byoung-Ho; Kwak, Jong-Gu; Lee, San-Gon; Yoon, Si-Woo; Bae, Young-Sun; Kim, Jin-Young; KSTAR Team

    2014-10-01

    In this talk, the recent achievements in MHD and energetic particle physics in KSTAR will be presented. Throughout the 2014 campaign, strategically important works in achieving KSTAR milestone including NTM stabilization, error field measurement, establishing disruption mitigation system, and identification of Alfvenic eigenmode are conducted. Real time feedback control of 2/1 NTM is successfully demonstrated with the search and suppression algorithm and the improved ECCD mirror control system. 3-D structure of n=1 intrinsic error field are fully explored with L- and H-mode plasma aiming not only to complete MID IVCC compass scan but also to set a groundwork toward understanding of KSTAR's unique feature, ELM suppression by n = 1 RMP. Elaborated q95 ~ 2 discharge regime is achieved without any error field correction by virtue of the extremely low intrinsic error field of KSTAR. The integrated disruption avoidance/mitigation system for the safety secured MA-class operation is well assessed. Further investigations of the energetic particle mode have been done with various control nobs of ECH, RMP and tailoring of NBI profile and mode identification efforts have been followed. Besides high priority works above, studies on sawtooth and run-away electron have made progresses.

  19. Monte Carlo simulations of intensity profiles for energetic particle propagation

    NASA Astrophysics Data System (ADS)

    Tautz, R. C.; Bolte, J.; Shalchi, A.

    2016-02-01

    Aims: Numerical test-particle simulations are a reliable and frequently used tool for testing analytical transport theories and predicting mean-free paths. The comparison between solutions of the diffusion equation and the particle flux is used to critically judge the applicability of diffusion to the stochastic transport of energetic particles in magnetized turbulence. Methods: A Monte Carlo simulation code is extended to allow for the generation of intensity profiles and anisotropy-time profiles. Because of the relatively low number density of computational particles, a kernel function has to be used to describe the spatial extent of each particle. Results: The obtained intensity profiles are interpreted as solutions of the diffusion equation by inserting the diffusion coefficients that have been directly determined from the mean-square displacements. The comparison shows that the time dependence of the diffusion coefficients needs to be considered, in particular the initial ballistic phase and the often subdiffusive perpendicular coefficient. Conclusions: It is argued that the perpendicular component of the distribution function is essential if agreement between the diffusion solution and the simulated flux is to be obtained. In addition, time-dependent diffusion can provide a better description than the classic diffusion equation only after the initial ballistic phase.

  20. Energetic particle fluxes in vicinity of Jupiter's moon Europa

    NASA Astrophysics Data System (ADS)

    Podzolko, Mikhail; Getselev, Igor; Gubar, Yuriy; Veselovsky, Igor

    Currently several projects of sending research space vehicles to Jupiter and its Galilean moons in 2020 are being developed. In particular, Russian Space Agency proposed the project of Europa lander. During the mission the spacecraft will be affected by charged particles of various origins. The greatest hazard will originate from powerful Jupiter's radiation belts, especially during the time of spacecraft operation near Europa and on its surface. The absorbed radiation dose during 2 months in Europa's orbit under shielding compared to that for "Galileo" spacecraft will amount to almost 1 megarad, the major contribution to it will originate from relativistic electrons. However, near Europa part of the charged particle flux will be shaded by the moon. Obviously, fluxes of particles of all energies on its surface will be lower by at least 2 times, than in the same point of space without Europa. But furthermore, the reduction of the fluxes in vicinity of Europa is nonuniform, and differs for the surface and the low-altitude orbit. This is caused by several factors: the complexity of particle trajectories near Europa and in Jupiter's magnetosphere in general, difference of Europa's orbital plane from Jupiter's geomagnetic equator plane, certain disturbance of Jupiter's magnetic field in vicinity of Europa, possible influence of electric fields and Europa's tenuous atmosphere. In the current study computations of energetic particle flux distribution near Europa and on its surface are made, taking into account several of the above-mentioned factors.

  1. Why do Saturn's energetic particle profiles look as they do?

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    A subset of the particle population within Saturn's magnetosphere is the one of energetic charged particles. Since 2004, the MIMI/LEMMS instrument onboard of Cassini is sampling Saturn's protons and electrons at energies of keV and MeV. We analyze mission-averaged measurements here. Outside Saturn's Main Rings and up to about five Saturn radii (RS) extend the radiation belts. Here, we focus on the region outside the belts and well within the dayside magnetopause. Since the particles are thought to be adiabatically transported, which changes their energy, it is physically meaningful to express the particle distribution in terms of adiabatic invariants. The particle distribution at fixed 1st and 2nd invariant generally decreases towards Saturn. This decrease is not related to losses close to Saturn but follows from adiabatic heating and therefore shape of the energy spectrum. An exception is protons within distances of about 8RS to Saturn that have energies below about 100keV. Only they are significantly lost from charge exchange with the gas environment, so that their radial profiles are steeper than usual. Additional to the overall decrease towards Saturn, we show that the profiles abruptly change their gradients at the orbits of the icy moons. This is especially well visible for electrons at Rhea but also apparent for protons. The fact that the moons influence the particle profiles even far away from the orbit indicates the presence of a radial coupling of the particle distribution, as it is caused by radial diffusion. We use a simple, analytical model to reproduce these gradient changes. The gradient of equatorially mirroring particles is steeper than of field-aligned ones. This is unexpected for the common mechanisms driving radial diffusion and therefore indicates that radial diffusion cannot be the only process acting in this region.

  2. PARTICLE ACCELERATION DURING MAGNETOROTATIONAL INSTABILITY IN A COLLISIONLESS ACCRETION DISK

    SciTech Connect

    Hoshino, Masahiro

    2013-08-20

    Particle acceleration during the magnetorotational instability (MRI) in a collisionless accretion disk was investigated by using a particle-in-cell simulation. We discuss the important role that magnetic reconnection plays not only on the saturation of MRI but also on the relativistic particle generation. The plasma pressure anisotropy of p > p{sub ||} induced by the action of MRI dynamo leads to rapid growth in magnetic reconnection, resulting in the fast generation of nonthermal particles with a hard power-law spectrum. This efficient particle acceleration mechanism involved in a collisionless accretion disk may be a possible model to explain the origin of high-energy particles observed around massive black holes.

  3. Reduced quasilinear models for energetic particles interaction with Alfvenic eigenmodes

    NASA Astrophysics Data System (ADS)

    Ghantous, Katy

    The Line Broadened Quasilinear (LBQ) and the 1.5D reduced models are able to predict the effect of Alfvenic eigenmodes' interaction with energetic particles in burning plasmas. This interaction can result in energetic-particle losses that can damage the first wall, deteriorate the plasma performance, and even prevent ignition. The 1.5D model assumes a broad spectrum of overlapping modes and, based on analytic expressions for the growth and damping rates, calculates the pressure profiles that the energetic particles relax to upon interacting with the modes. 1.5D is validated with DIII-D experiments and predicted neutron losses consistent with observation. The model is employed to predict alpha-particle fusion-product losses in a large-scale operational parameter-space for burning plasmas. The LBQ model captures the interaction both in the regime of isolated modes as well as in the conventional regime of overlapping modes. Rules were established that allow quasilinear equations to replicate the expected steady-state saturation levels of isolated modes. The fitting formula is improved and the model is benchmarked with a Vlasov code, BOT. The saturation levels are accurately predicted and the mode evolution is well-replicated in the case of steady-state evolution where the collisions are high enough that coherent structures do not form. When the collisionality is low, oscillatory behavior can occur. LBQ can also exhibit non-steady behavior, but the onset of oscillations occurs for much higher collisional rates in BOT than in LBQ. For certain parameters of low collisionality, hole-clump creation and frequency chirping can occur which are not captured by the LBQ model. Also, there are cases of non-steady evolution without chirping which is possible for LBQ to study. However the results are inconclusive since the periods and amplitudes of the oscillations in the mode evolution are not well-replicated. If multiple modes exist, they can grow to the point of overlap which

  4. Radial dependence of solar energetic particles derived from the 15 March 2013 solar energetic particle event and global MHD simulation

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Chun; Liou, Kan; Wu, S. T.; Dryer, Murray; Plunkett, Simon

    2016-03-01

    We study an unusual solar energetic particle (SEP) event that was associated with the coronal mass ejection (CME) on March 15, 2013. Enhancements of the SEP fluxes were first detected by the ACE spacecraft at 14:00 UT, ˜7 hours after the onset of the CME (07:00 UT), and the SEP's peak intensities were recorded ˜36 hours after the onset of the CME. Our recent study showed that the CME-driven shock Mach number, based on a global three-dimensional (3-D) magnetohydrodynamic (MHD) simulation, is well correlated with the time-intensity of 10-30 MeV and 30-80 MeV protons. Here we focus on the radial dependence (r-α) of 4He (3.43-41.2 MeV/n) and O (7.30-89.8 MeV/n) energetic particles from ACE/SIS. It is found that the scaling factor (α) ranges between 2 and 4 for most of the energy channels. We also found that the correlation coefficients tend to increase with SEP energies.

  5. Field-aligned Transport and Acceleration of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Borovikov, D.; Sokolov, I.; Tenishev, V.; Gombosi, T. I.

    2015-12-01

    Solar Energetic Particle (SEP) phenomena represent one of the major components of space weather. Often, but not exclusively associated with Coronal Mass Ejections (CMEs), they pose a significant scientific as well as practical interest. As these particles originate at such explosive events, they have energies up to several GeV. SEP may cause disruptions in operations of space instruments and spacecrafts and are dangerous to astronauts. For this reason, studies of SEP events and predictions of their impact are of great importance. The motion and acceleration of SEP, though kinetic in nature, is governed by Interplanetary Magnetic Field (IMF) and its disturbances. Therefore, a consistent and accurate simulation and predictive tool must include a realistic MHD model of IMF. At the same time, transport of SEP is essentially one-dimensional as at high energies particles are tied to magnetic field lines. This allows building a model that can effectively map active regions on the solar surface onto various regions of the Solar System thus predicting the affected regions of the at any distance from the Sun. We present the first attempt to construct a model that employs coupling of MHD and kinetic models. The former describes the evolution of IMF disturbed by CME, while the latter simulates particles moving along the field lines extracted from MHD model. The first results are provided.

  6. Precision Modeling of Solar Energetic Particle Intensity and Anisotropy Profiles

    NASA Astrophysics Data System (ADS)

    Ruffolo, D.; Sáiz, A.; Bieber, J. W.; Evenson, P.; Pyle, R.; Rujiwarodom, M.; Tooprakai, P.; Wechakama, M.; Khumlumlert, T.

    2006-12-01

    A focused transport equation for solar energetic particles is sufficiently complex that simple analytic approximations are generally inadequate, but the physics is sufficiently well established to permit precise numerical modeling of high energy particle observations at various distances from the Sun. We demonstrate how observed profiles of intensity and anisotropy vs. time can be quantitatively fit to determine an optimal injection profile at the Sun, scattering mean free path λ, and magnetic configuration. For several ground level enhancements (GLE) of solar energetic particles at energies ~ 1 GeV, the start time of injection has been determined to 1 or 2 minutes. In each case this start time coincides, within that precision, to the soft X-ray peak time, when the flare's primary energy release has ended. This is not inconsistent with acceleration at a coronal mass ejection (CME)-driven shock, though the rapid timescale is challenging to understand. For the GLE of 2005 January 20, λ decreases substantially over ~ 10 minutes, which is consistent with concepts of proton-amplified waves. The GLE of 2000 July 14 is properly fit only when a magnetic bottleneck beyond Earth is taken into account, a feature later confirmed by NEAR observations. The long-standing puzzle of the 1989 October 22 event can now be explained by simultaneous injection of relativistic solar particles along both legs of a closed interplanetary magnetic loop, while other reasonable explanations fail the test of quantitative fitting. The unusually long λ (confirming many previous reports) and a low turbulent spectral index hint at unusual properties of turbulence in the loop. While the early GLE peak on 2003 October 28 remains a mystery, the main peak's strong anisotropy is inconsistent with a suggestion of injection along the far leg of a magnetic loop; quantitative fitting fails because of reverse focusing during Sunward motion. With these modeling capabilities, one is poised to take full

  7. The composition of heavy ions in solar energetic particle events

    NASA Technical Reports Server (NTRS)

    Fan, C. Y.; Gloeckler, G.; Hovestadt, D.

    1983-01-01

    Recent advances in determining the elemental, charge state, and isotopic composition of or approximate to 1 to or approximate to 20 MeV per nucleon ions in solar energetic particle (SEP) events and outline our current understanding of the nature of solar and interplanetary processes which may explain the observations. Average values of relative abundances measured in a large number of SEP events were found to be roughly energy independent in the approx. 1 to approx. 20 MeV per nucleon range, and showed a systematic deviation from photospheric abundances which seems to be organized in terms of the first ionization potential of the ion. Direct measurements of the charge states of SEPs revealed the surprisingly common presence of energetic He(+) along with heavy ion with typically coronal ionization states. High resolution measurements of isotopic abundance ratios in a small number of SEP events showed these to be consistent with the universal composition except for the puzzling overabundance of the SEP(22)Ne/(20)Ne relative to this isotopes ratio in the solar wind. The broad spectrum of observed elemental abundance variations, which in their extreme result in composition anomalies characteristic of (3)He rich, heavy ion rich and carbon poor SEP events, along with direct measurements of the ionization states of SEPs provided essential information on the physical characteristics of, and conditions in the source regions, as well as important constraints to possible models for SEP production.

  8. Interactions of energetic particles and clusters with solids

    SciTech Connect

    Averback, R.S.; Hsieh, Horngming . Dept. of Materials Science and Engineering); Diaz de la Rubia, T. ); Benedek, R. )

    1990-12-01

    Ion beams are being applied for surface modifications of materials in a variety of different ways: ion implantation, ion beam mixing, sputtering, and particle or cluster beam-assisted deposition. Fundamental to all of these processes is the deposition of a large amount of energy, generally some keV's, in a localized area. This can lead to the production of defects, atomic mixing, disordering and in some cases, amorphization. Recent results of molecular dynamics computer simulations of energetic displacement cascades in Cu and Ni with energies up to 5 keV suggest that thermal spikes play an important role in these processes. Specifically, it will be shown that many aspects of defect production, atomic mixing and cascade collapse'' can be understood as a consequence of local melting of the cascade core. Included in this discussion will be the possible role of electron-phonon coupling in thermal spike dynamics. The interaction of energetic clusters of atoms with solid surfaces has also been studied by molecular dynamics simulations. this process is of interest because a large amount of energy can be deposited in a small region and possibly without creating point defects in the substrate or implanting cluster atoms. The simulations reveal that the dynamics of the collision process are strongly dependent on cluster size and energy. Different regimes where defect production, local melting and plastic flow dominate will be discussed. 43 refs., 7 figs.

  9. The composition of heavy ions in solar energetic particle events

    NASA Technical Reports Server (NTRS)

    Fan, C. Y.; Gloeckler, G.; Hovestadt, D.

    1984-01-01

    Recent advances in determining the elemental, charge state, and isotopic composition of or approximate to 1 to or approximate to 20 MeV per nucleon ions in solar energetic particle (SEP) events and outline our current understanding of the nature of solar and interplanetary processes which may explain the observations. Average values of relative abundances measured in a large number of SEP events were found to be roughly energy independent in the approx. 1 to approx. 20 MeV per nucleon range, and showed a systematic deviation from photospheric abundances which seems to be organized in terms of the first ionization potential of the ion. Direct measurements of the charge states of SEPs revealed the surprisingly common presence of energetic He(+) along with heavy ion with typically coronal ionization states. High resolution measurements of isotopic abundance ratios in a small number of SEP events showed these to be consistent with the universal composition except for the puzzling overabundance of the SEP(22)Ne/(20)Ne relative to this isotopes ratio in the solar wind. The broad spectrum of observed elemental abundance variations, which in their extreme result in composition anomalies characteristic of (3)He rich, heavy ion rich and carbon poor SEP events, along with direct measurements of the ionization states of SEPs provided essential information on the physical characteristics of, and conditions in the source regions, as well as important constraints to possible models for SEP production. Previously announced in STAR as N83-20886

  10. Prediction of Solar Energetic Particle Trapping in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Engel, M.; Larsen, B. A.

    2012-12-01

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

  11. Measurement of energetic particle radiation at the synchronous altitude aboard ATS-6

    NASA Technical Reports Server (NTRS)

    Paulikas, G. A.; Blake, J. B.; Imamoto, S. S.

    1975-01-01

    The Aerospace Corporation energetic electron-proton spectrometer operating on ATS-6 is described. This experiment detects energetic electrons in four channels between 140 keV and greater than 3.9 MeV, measures energetic protons in five energy channels between 2.3 and 80 MeV and energetic alpha particles in three channels between 9.4 and 94 MeV. After more than a year of operation in orbit, the experiment continues to return excellent data on the behavior of energetic magnetospheric electrons as well as information regarding the fluxes of solar protons and alpha particles.

  12. Energetic charged particle beams for disablement of mines

    SciTech Connect

    Wuest, C.R.

    1995-03-27

    LLNL has an ongoing program of weapons disablement using energetic charged particle beams; this program combines theoretical and experimental expertise in accelerators, high-energy and nuclear physics, plasma physics and hydrodynamics to simulate/measure effects of electron and proton beams on weapons. This paper reviews work by LLNL, LANL and NSWC on detonating sensitive and insensitive high explosives and land mines using high-current electron beams. Computer simulations are given. 20--160 MeV electron beams incident on wet/dry soils are being studied, along with electron beam propagation in air. Compact high current, high energy accelerators are being developed for mine clearing. Countermine missions of interest are discussed. 25 refs., 9 figs.

  13. Solar abundances as derived from solar energetic particles

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1989-01-01

    Recent studies have shown that there are well defined average abundances of heavy (Z above 2) solar energetic particles (SEPs), with variations in the acceleration and propagation producing a systematic flare-to-flare fractionation that depends on the charge per unit mass of the ion. Correcting the average SEP abundances for this fractionation yields SEP-derived coronal abundances for 20 elements. High-resolution SEP studies have also provided isotopic abundances for five elements. SEP-derived abundances indicate that elements with high first ionization potentials (greater than 10 eV) are depleted in the corona relative to the photosphere and provide new information on the solar abundance of C and Ne-22.

  14. Enceladus flybys in the view of energetic particles

    NASA Astrophysics Data System (ADS)

    Krupp, N.; Roussos, E.; Kotova, A.; Khurana, K. K.; Jones, G. H.; Simon, S.

    2015-10-01

    We report on particle measurements in the vicinity of Enceladus in the Saturnian magnetosphere taken onboard the Cassini Spacecraft between 2005 and 2015. Enceladus, embedded in Saturn's radiation belts has been investigated by Cassini during 23 close flybys including those where the spacecraft went through the south polar plumes of the moon. This paper is an update of the results from the first 14 flybys published by [2]. We report on the results of energetic electron measurements in the energy range 27 keV to 21 MeV taken by the Low Energy Magnetospheric Measurement System LEMMS, part of the Magnetospheric Imaging Instrument MIMI on board combined with measurements of the magnetometer instrument MAG and the Electron Spectrometer ELS of the Plasma instrument CAPS on board the spacecraft.

  15. Galactic energetic particles and their radiative yields in clusters

    NASA Astrophysics Data System (ADS)

    Rephaeli, Yoel; Sadeh, Sharon

    2016-05-01

    As energetic particles diffuse out of radio and star-forming galaxies (SFGs), their intracluster density builds up to a level that could account for a substantial part or all the emission from a radio halo. We calculate the particle time-dependent, spectro-spatial distributions from a solution of a diffusion equation with radio galaxies as sources of electrons and SFGs as sources of both electrons and protons. Whereas strong radio galaxies are typically found in the cluster (e.g., Coma) core, the fraction of SFGs increases with distance from the cluster center. Scaling particle escape rates from their sources to the reasonably well determined Galactic rates, and for realistic gas density and magnetic field spatial profiles, we find that predicted spectra and spatial profiles of radio emission from primary and secondary electrons are roughly consistent with those deduced from current measurements of the Coma halo (after subtraction of emission from the relic Coma A). Nonthermal x-ray emission is predicted to be mostly by Compton scattering of electrons from radio galaxies off the CMB, whereas γ -ray emission is primarily from the decay of neutral pions produced in interactions of protons from SFGs with protons in intracluster gas.

  16. OBSERVED CORE OF A GRADUAL SOLAR ENERGETIC PARTICLE EVENT

    SciTech Connect

    Kocharov, L.; Valtonen, E.; Reiner, M. J.; Thompson, B. J.; Klassen, A.

    2010-12-20

    Using space-borne particle and EUV detection and radio spectrograms from both ground-based and space-borne instruments, we study the first phase of the major solar energetic particle (SEP) event associated with the western solar flare and fast and wide coronal mass ejection (CME) on 2000 April 4. The SEP event being observed at the magnetic connection to the eruption's center starts with deka-MeV nucl{sup -1} helium- and relativistic electron-rich production from coronal sources identified with the electromagnetic diagnostics and the SEP event modeling. The broadband observations and modeling of the initial phase of the 'well-connected' major SEP event support the idea that acceleration of SEPs starts in the helium-rich plasma of the eruption's core in association with coronal shocks and magnetic reconnections caused by the CME liftoff, and that the coronal component dominates during the first hour of the SEP event considered, not yet being shielded by the CME bow shock in the solar wind. The first phase of the SEP event is followed by a second phase of SEP production associated with a decelerating CME-driven shock wave in the solar wind, which accelerates ions from a distinct, helium-poor seed particle population that may originate from the CME interaction with a coronal streamer.

  17. Simulations of energetic particles interacting with nonlinear anisotropic dynamical turbulence

    NASA Astrophysics Data System (ADS)

    Heusen, M.; Shalchi, A.

    2016-09-01

    We investigate test-particle diffusion in dynamical turbulence based on a numerical approach presented before. For the turbulence we employ the nonlinear anisotropic dynamical turbulence model which takes into account wave propagation effects as well as damping effects. We compute numerically diffusion coefficients of energetic particles along and across the mean magnetic field. We focus on turbulence and particle parameters which should be relevant for the solar system and compare our findings with different interplanetary observations. We vary different parameters such as the dissipation range spectral index, the ratio of the turbulence bendover scales, and the magnetic field strength in order to explore the relevance of the different parameters. We show that the bendover scales as well as the magnetic field ratio have a strong influence on diffusion coefficients whereas the influence of the dissipation range spectral index is weak. The best agreement with solar wind observations can be found for equal bendover scales and a magnetic field ratio of δ B / B0 = 0.75.

  18. Solar energetic particle interactions with the Venusian atmosphere

    NASA Astrophysics Data System (ADS)

    Plainaki, Christina; Paschalis, Pavlos; Grassi, Davide; Mavromichalaki, Helen; Andriopoulou, Maria

    2016-07-01

    In the context of planetary space weather, we estimate the ion production rates in the Venusian atmosphere due to the interactions of solar energetic particles (SEPs) with gas. The assumed concept for our estimations is based on two cases of SEP events, previously observed in near-Earth space: the event in October 1989 and the event in May 2012. For both cases, we assume that the directional properties of the flux and the interplanetary magnetic field configuration would have allowed the SEPs' arrival at Venus and their penetration to the planet's atmosphere. For the event in May 2012, we consider the solar particle properties (integrated flux and rigidity spectrum) obtained by the Neutron Monitor Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model (Plainaki et al., 2010, 2014) applied previously for the Earth case and scaled to the distance of Venus from the Sun. For the simulation of the actual cascade in the Venusian atmosphere initiated by the incoming particle fluxes, we apply the DYASTIMA code, a Monte Carlo (MC) application based on the Geant4 software (Paschalis et al., 2014). Our predictions are afterwards compared to other estimations derived from previous studies and discussed. Finally, we discuss the differences between the nominal ionization profile due to galactic cosmic-ray-atmosphere interactions and the profile during periods of intense solar activity, and we show the importance of understanding space weather conditions on Venus in the context of future mission preparation and data interpretation.

  19. Rocket observation of soft energetic particles at the magnetic equator

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.

    1974-01-01

    Results from a rocket-borne ion mass spectrometer flown near the magnetic equator at 0108 LMT, March 10, 1970, exhibit an unusual background current above 200 km. This current is observed to increase 3.5 orders of magnitude between 200 and 260 km before maximizing to a fixed value from 260 km to the 295 km apogee of the flight. Properties of the background combined with laboratory measurements have permitted probable identification of the background source as 2-20 keV electrons or protons. Maximum electron fluxes have been estimated to be of the order 10 to the 10th power particles/sq cm-sec-ster in accord with ISIS-1 satellite measurements at higher altitudes. The background was not observed on an earlier flight at 1938 LMT, suggesting the particles to be trapped in a blet which drifted below 300 km between the two flights. The low altitude penetration of these fluxes may have been related to the great magnetic storm of March 8. Simultaneous measurements of the thermal ion distribution are compared with these results and qualitatively suggest that the soft energetic particles are responsible for an observed O2(+) and NO(+) enhancement.

  20. Modeling of Solar Energetic Particles in Interplanetary Space

    NASA Astrophysics Data System (ADS)

    Vainio, Rami; Agueda, Neus; Aran, Angels; Lario, David

    Solar energetic particles (SEPs) in the interplanetary (IP) medium are transported under the influence of electromagnetic fields of the solar wind. These fields consists of the smooth background fields, which can be modeled by the MHD equations governing the expansion of the solar wind, and of the small-scale fluctuations (waves or turbulence) that scatter the particles in pitch angle and act as agents enabling their acceleration at IP shock waves. We review theoretical models of SEP transport and acceleration in the IP medium. We start from the simple analytical approaches (diffusion models), which assume quasi-isotropic particle distributions, and then continue to the more accurate numerical approaches based on the focused transport equation, not making this simplifying assumption. A careful analysis of two SEP events, an impulsive and a gradual one, is presented and the spatial scaling of their peak intensities, differential fluences and time-integrated net fluxes is discussed. We conclude that rather simple scaling laws for these quantities can be obtained for impulsive events but no simple scaling laws can be expected to govern the gradual SEP events

  1. Scenarios for the nonlinear evolution of alpha particle induced Alfven wave instability

    SciTech Connect

    Berk, H.L.; Breizman, B.N.; Ye, Huanchun.

    1992-03-01

    Various nonlinear scenarios are given for the evolution of energetic particles that are slowing down in a background plasma and simultaneously causing instability of the background plasma waves. If the background damping is sufficiently weak, a steady-state wave is established as described by Berk and Breizman. For larger background damping rate pulsations develop. Saturation occurs when the wave amplitude rises to where the wave trapping frequency equals the growth rate. The wave then damps due to the small background dissipation present and a relatively long quiet interval exists between bursts while the free energy of the distribution is refilled by classical transport. In this scenario the anomalous energy loss of energetic particles due to diffusion is small compared to the classical collisional energy exchange with the background plasma. However, if at the trapping frequency, the wave amplitude is large enough to cause orbit stochasticity, a phase space explosion'' occurs where the wave amplitudes rise to higher levels which leads to rapid loss of energetic particles.

  2. Scenarios for the nonlinear evolution of alpha particle induced Alfven wave instability

    SciTech Connect

    Berk, H.L.; Breizman, B.N.; Ye, Huanchun

    1992-03-01

    Various nonlinear scenarios are given for the evolution of energetic particles that are slowing down in a background plasma and simultaneously causing instability of the background plasma waves. If the background damping is sufficiently weak, a steady-state wave is established as described by Berk and Breizman. For larger background damping rate pulsations develop. Saturation occurs when the wave amplitude rises to where the wave trapping frequency equals the growth rate. The wave then damps due to the small background dissipation present and a relatively long quiet interval exists between bursts while the free energy of the distribution is refilled by classical transport. In this scenario the anomalous energy loss of energetic particles due to diffusion is small compared to the classical collisional energy exchange with the background plasma. However, if at the trapping frequency, the wave amplitude is large enough to cause orbit stochasticity, a phase space ``explosion`` occurs where the wave amplitudes rise to higher levels which leads to rapid loss of energetic particles.

  3. Simulation study of high-frequency energetic particle driven geodesic acoustic mode

    SciTech Connect

    Wang, Hao Ido, Takeshi; Osakabe, Masaki; Todo, Yasushi

    2015-09-15

    High-frequency energetic particle driven geodesic acoustic modes (EGAM) observed in the large helical device plasmas are investigated using a hybrid simulation code for energetic particles and magnetohydrodynamics (MHD). Energetic particle inertia is incorporated in the MHD momentum equation for the simulation where the beam ion density is comparable to the bulk plasma density. Bump-on-tail type beam ion velocity distribution created by slowing down and charge exchange is considered. It is demonstrated that EGAMs have frequencies higher than the geodesic acoustic modes and the dependence on bulk plasma temperature is weak if (1) energetic particle density is comparable to the bulk plasma density and (2) charge exchange time (τ{sub cx}) is sufficiently shorter than the slowing down time (τ{sub s}) to create a bump-on-tail type distribution. The frequency of high-frequency EGAM rises as the energetic particle pressure increases under the condition of high energetic particle pressure. The frequency also increases as the energetic particle pitch angle distribution shifts to higher transit frequency. It is found that there are two kinds of particles resonant with EGAM: (1) trapped particles and (2) passing particles with transit frequency close to the mode frequency. The EGAMs investigated in this work are destabilized primarily by the passing particles whose transit frequencies are close to the EGAM frequency.

  4. Vertical coherent instabilities in bunched particle-beams

    SciTech Connect

    Ruth, R.D.

    1981-07-01

    The purpose of this paper is to study the vertical coherent instabilities which occur in bunched particle beams. The problem is complicated by the fact that the velocity of a single particle in a bunch is not constant, but rather consists of an equilibrium velocity and an oscillation about that. This synchrotron oscillation occurs at a frequency which is in general much less than the other characteristic frequencies of the system: the revolution frequency and the transverse betatron frequencies. The approach used here to study coherent instabilities illuminates the effect of the synchrotron frequency in setting the time scale for an instability, without making restrictive assumptions on the relative size of the synchrotron frequency and the coherent frequency shift (or growth rate).

  5. Anisotropy-driven collective instability in intense charged particle beams

    NASA Astrophysics Data System (ADS)

    Startsev, Edward A.; Davidson, Ronald C.; Qin, Hong

    2005-12-01

    The classical electrostatic Harris instability is generalized to the case of a one-component intense charged particle beam with anisotropic temperature including the important effects of finite transverse geometry and beam space charge. For a long, coasting beam, the eigenmode code bEASt have been used to determine detailed 3D stability properties over a wide range of temperature anisotropy and beam intensity. A simple theoretical model is developed which describes the essential features of the linear stage of the instability. Both the simulations and the analytical theory clearly show that moderately intense beams are linearly unstable to short-wavelength perturbations provided the ratio of the longitudinal temperature to the transverse temperature is smaller than some threshold value. The delta-f particle-in-cell code BEST has been used to study the detailed nonlinear evolution and saturation of the instability.

  6. On the Interaction Between Highly Energetic Charged Particles and the Lunar Regolith

    NASA Astrophysics Data System (ADS)

    Jordan, A. P.; Stubbs, T. J.; Zeitlin, C.; Spence, H. E.; Schwadron, N. A.; Zimmerman, M. I.; Farrell, W. M.

    2012-03-01

    In this study we explore how galactic cosmic rays and solar energetic particles contribute to deep dielectric charging within the lunar regolith and how these particles affect lunar surface charging in tenuous plasma environments.

  7. Solar Sources of Earth-affecting Energetic Particles

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat

    2012-01-01

    Particle radiation from the Sun is one of the most important sources of hazardous space weather in the vicinity of Earth. Detailed studies of the origin of the so-called large solar energetic particle (SEP) events became possible only during the solar cycle 23, thanks to the availability of nearly continuous observation of the solar sources ofthese events. In particular, coronal mass ejections (CMEs), which are found to be a key requirement for the occurrence of an SEP event, have been recorded continuously only starting in the 1990s. The physical connection between CMEs and SEPs is that the CMEs drive a fast-mode MHD shock, which accelerates SEPs in the corona and interplanetary medium. The earliest indication of a shock is the occurrence of a type II radio burst at frequencies anywhere from more than a hundred MHz to a few MHz. Recent investigations using STEREO observations have revealed that the shock forms very close to the Sun - a mere 100,000 km above the surface. The shock formation depends not only on the CME properties, but also on the physical conditions in the ambient medium that supports shock propagation. This paper considers extreme cases of SEP events and the associated CMEs and type II radio bursts to illustrate the variability observed in SEP event properties. Comparison will be made between the events of solar cycles 23 and 24.

  8. Energetic Particles in the far and near Environment of Pluto

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Hill, M. E.; McNutt, R. L., Jr.; Brown, L. E.; Kusterer, M. B.; Vandegriff, J. D.; Smith, H. T.; Mitchell, D. G.; Haggerty, D. K.; Bagenal, F.; Krimigis, S. M.; Lisse, C. M.; Delamere, P. A.; Elliott, H. A.; Horanyi, M.; McComas, D. J.; Piquette, M. R.; Poppe, A. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Valek, P. W.; Weidner, S.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, A.

    2015-12-01

    The New Horizons spacecraft was launched in 2006, passed Jupiter and its magnetotail, took continuous measurements in the solar wind throughout the recent years, and flew by Pluto in July 2015. The onboard PEPSSI instrument measures ion and electron intensities, masses, and energies in the keV to MeV range. The closest approach distance to Pluto was 11 Pluto radii, inside the orbit of Charon. Data taken near Pluto is downlinked throughout August. We will present analysis of this data and set it into context with previous measurements. We expect a number of interesting particle structures around Pluto. Parts of Pluto's molecular nitrogen atmosphere is escaping and will co-orbit with Pluto, potentially forming a partial gas torus. This torus can be additionally sourced by other Kuiper belt objects. The neutrals are eventually ionized and pick-up by the solar wind brings them into the PEPSSI energy range. The measured ion densities can be used to constrain the Pluto torus. Pluto is not expected to have an intrinsic magnetic field, but the energetic particle data can be used to infer its properties, if any. Pluto interacts instead with the solar wind via the pick-up of its ions and the magnetic fields created by currents in its ionosphere. The relative role of these mechanisms can be revealed by the flyby data and directly compared to data that was taken at Jupiter with identical instrumentation.

  9. Exposure to galactic cosmic radiation and solar energetic particles.

    PubMed

    O'Sullivan, D

    2007-01-01

    Several investigations of the radiation field at aircraft altitudes have been undertaken during solar cycle 23 which occurred in the period 1993-2003. The radiation field is produced by the passage of galactic cosmic rays and their nuclear reaction products as well as solar energetic particles through the Earth's atmosphere. Galactic cosmic rays reach a maximum intensity when the sun is least active and are at minimum intensity during solar maximum period. During solar maximum an increased number of coronal mass ejections and solar flares produce high energy solar particles which can also penetrate down to aircraft altitudes. It is found that the very complicated field resulting from these processes varies with altitude, latitude and stage of solar cycle. By employing several active and passive detectors, the whole range of radiation types and energies were encompassed. In-flight data was obtained with the co-operation of many airlines and NASA. The EURADOS Aircraft Crew in-flight data base was used for comparison with the predictions of various computer codes. A brief outline of some recent studies of exposure to radiation in Earth orbit will conclude this contribution. PMID:17846031

  10. Energetic particles, tangential discontinuities, and solar flux tubes

    NASA Astrophysics Data System (ADS)

    Neugebauer, M.; Giacalone, J.

    2015-10-01

    This study examines the probable sources of sharp changes in the flux of energetic particles (EPs) in the solar wind. Data acquired by the ACE Low Energy Magnetic Spectrometer sensors during 1999 were used to identify EP boundaries that were not located at interplanetary shocks or caused by intermittent connection to the Earth's bow shock. It was found that at least 68%, and probably 80%, of such boundaries occur at significant changes in the plasma and magnetic field in the solar wind. Those changes are consistent with crossing preexisting tangential discontinuities or flux tube boundaries rather than by local MHD turbulence or time-dependent bursts of acceleration. Because some of the EP boundaries would not have been detected by Borovsky's (2008) analysis of flux tube boundaries, it is concluded that such boundaries in the solar wind are at least 30% more prevalent than previously suggested. The result can also be used to explain some observations of localized variations in EP flux both ahead of and behind the interplanetary shocks where particle acceleration occurred without requiring local acceleration.

  11. Developing an Empirical Model for Predicting Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Quinn, R. A.; Winter, L. M.; Ledbetter, K.; Ashley, S. F.

    2014-12-01

    Solar energetic particle (SEP) events are powerful enhancements in the particle flux received at Earth. These events, often related to coronal mass ejections, can be disruptive to ionospheric communications, destructive to satellites, and pose a health risk to astronauts. To develop a useful forecast for the onset time and peak flux of SEP events, we are examining the radio burst, proton, and electron properties associated with the SEPs of the current solar cycle. Using the Wind/WAVES radio observations from 2010-2013, we analyzed the 123 decametric-hectometric type II solar radio burst properties, the associated type III burst properties, and their correlation with SEP properties determined from analysis of the Geostationary Operational Environmental Satellite (GOES) observations. Through a principal component and logistic regression analyses, we find that the radio properties alone can be used to predict the occurrence of an SEP event with a false alarm rate of 17%, a probability of detection of 65%, and with 88% of the classifications correct. We also explore the use of the > 2 MeV electron flux to forecast proton peak flux and event onset time, with preliminary results suggesting a correlation between the peak electron and proton flux.

  12. Coronal Shock Waves and Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Cliver, Edward

    Recent evidence supports the view first expressed by Wild, Smerd, and Weiss in 1963 that large solar energetic particle (SEP) events are a consequence of shock waves manifested by radio type II bursts. Following Tylka et al. (ApJ 625, 474, 2005), our picture of SEP acceleration at shocks now includes the effects of variable seed particle population and shock geometry. By taking these factors into account, Tylka and Lee (ApJ 646, 1319, 2006; see also Sandroos Vainio, ApJ 662, L127, 2007; AA 507, L21, 2009) were able to account for the charge-to-mass variability in high-Z ions first reported by Breneman and Stone in 1985. Recent studies of electron-to-proton ratios, both in interplanetary space (Cliver Ling, ApJ 658, 1349, 2007; Dietrich et al., in preparation, 2010) and in gamma-ray-line events (Shih et al., ApJ 698, L152, 2009), also support the view that large SEP events originate in coronal shocks and not in solar flares. Concurrent with the above developments, there is growing evidence that coronal shocks are driven by coronal mass ejections rather than by flare pressure pulses.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  14. The Role of Precipitating Energetic Particles in Coupling Atmospheric Regions

    NASA Astrophysics Data System (ADS)

    Bailey, S. M.; Randall, C. E.; Solomon, S. C.; Yee, S.; Kozyra, J. U.; Baker, D. N.

    2010-12-01

    A key missing element in our understanding of the Sun-Earth system is the response of the atmosphere when precipitating particle energy is redistributed via dynamical, chemical, and radiative processes. Elucidating the coupling intrinsic to this response is a prerequisite for understanding and predicting variability in and across many atmospheric regions. A priority for future observations is the Energetic Particle Precipitation (EPP) Indirect Effect (IE), by which odd nitrogen compounds produced by EPP in the upper atmosphere descend to the stratosphere, perturbing ozone chemistry and thus the radiative balance of the middle atmosphere. It has been shown that EPP IE occurs nearly every year in both hemispheres, and is modulated by variability in both the EPP and atmospheric meteorology. In this talk, we will summarize the current state of knowledge of EPP IE, the observational evidence for it in the last few decades, and what is required of future observations. We will discuss the advantages and disadvantages of various measurement techniques for observing odd nitrogen and descent, along with uncertainties in the analysis methods.

  15. Solar photospheric and coronal abundances from solar energetic particle measurements

    SciTech Connect

    Breneman, H.H.

    1985-01-01

    Observations of solar energetic particles (SEPs) from 22 solar flares in the 1977-1982 time period are reported. The observations were made by the cosmic ray subsystem on board the Voyager 1 and 2 spacecraft. SEP abundances were obtained for all elements with 3 less than or equal to Z less than or equal to 30 except Li, Be, B, F, Sc, V, Co and Cu, for which upper limits have been obtained. Statistically meaningful abundances of several rare elements (e.g., P, Cl, K, Ti, Mn) were determined for the first time, and the average abundances of the more abundant elements were determined with improved precision, typically a factor of three better than the best previous determinations. Previously reported results concerning the dependence of the fractionation of SEPs relative to photosphere on first ionization potential (FIP) have been confirmed and amplified upon with the new data. The monotonic Z dependence of the variation between flares noted by earlier studies was found to be interpretable as a fractionation, produced by acceleration of the particles from the corona and their propagation through interplanetary space, which is ordered by the ionic charge-to-mass ratio Q/M of the species making up the SEPs. It was found that Q/M is the primary organizing parameter of acceleration and propagation effects in SEPs, as evidenced by the dependence on Q/M of time, spatial and energy dependence within flares and of the abundance variability from flare to flare.

  16. Element Abundances in Solar Energetic Particles and the Solar Corona

    NASA Astrophysics Data System (ADS)

    Reames, Donald V.

    2014-03-01

    This is a study of abundances of the elements He, C, N, O, Ne, Mg, Si, S, Ar, Ca, and Fe in solar energetic particles (SEPs) in the 2 - 15 MeV amu-1 region measured on the Wind spacecraft during 54 large SEP events occurring between November 1994 and June 2012. The origin of most of the temporal and spatial variations in abundances of the heavier elements lies in rigidity-dependent scattering during transport of the particles away from the site of acceleration at shock waves driven out from the Sun by coronal mass ejections (CMEs). Variation in the abundance of Fe is correlated with the Fe spectral index, as expected from scattering theory but not previously noted. Clustering of Fe abundances during the "reservoir" period, late in SEP events, is also newly reported. Transport-induced enhancements in one region are balanced by depletions in another, thus, averaging over these variations produces SEP abundances that are energy independent, confirms previous SEP abundances in this energy region, and provides a credible measure of element abundances in the solar corona. These SEP-determined coronal abundances differ from those in the solar photosphere by a well-known function that depends upon the first ionization potential (FIP) or ionization time of the element.

  17. Interplanetary propagation of flare-associated energetic particles

    NASA Technical Reports Server (NTRS)

    Ma Sung, L. S.; Earl, J. A.

    1978-01-01

    The basic propagation process of flare-associated energetic particles in interplanetary space is studied on the basis of a model which combines a Gaussian coronal injection profile and interplanetary particle densities found by a theory of focused diffusion. The model is used to describe 30 electron and proton events which originate from the western hemisphere of the sun. A comparison of calculated and observed density profiles shows that the scattering mean free path is 0.1-0.3 AU for 4-80 MeV protons. The value is two or three times smaller for 0.5-1.1 and 3-12 MeV electrons. Thus the scattering mean free path is only slightly rigidity-dependent, contrary to that predicted by the quasi-linear theory of pitch-angle scattering. The rms width is found to be less than an hour for most proton and electron events. This width, which decreases with velocity, is not rigidity-dependent.

  18. Energetic Particle Precipitation Effects Observed in LIMS Data

    NASA Astrophysics Data System (ADS)

    Holt, L. A.; Randall, C. E.; Harvey, V. L.; Stiller, G. P.; Funke, B.; López-Puertas, M.; Remsberg, E. E.

    2008-12-01

    The Limb Infrared Monitor of the Stratosphere (LIMS) observed stratospheric enhancements in NO2 inside the Arctic polar vortex during the winter of 1978-1979. These enhancements were attributed to the descent of NOx originally produced by precipitating energetic particles in the upper atmosphere. Although few observations of such stratospheric NOx enhancements were made during the decade succeeding the LIMS measurements, investigations in the last decade have shown abundant evidence for these enhancements. Interannual variability in the enhancements appears to be controlled both by the amount of particle precipitation and the prevailing meteorological conditions, which dictate the efficiency with which NOx is transported from the upper atmosphere into the stratosphere. In this presentation, recent satellite measurements of the temporal evolution of NOx in the polar vortex are compared to the LIMS measurements. Our goal is to investigate whether the enhancements were observed by LIMS because of enhanced geomagnetic activity and/or anomalous dynamical conditions, or whether the nighttime observing capability of LIMS simply enabled it to detect the NOx enhancements under nominal conditions.

  19. Energetic particle energy deposition in Titan's upper atmosphere

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; Smith, H. T.; Mitchell, D. G.; Paranicas, C. P.; Rymer, A. M.; Bell, J. M.; Waite, J. H., Jr.; Mandt, K. E.

    2012-04-01

    Titan’s upper atmosphere has been observed to be variable on a pass-by-pass basis. During the nominal mission where the Cassini Ion and Neutral Mass Spectrometer (INMS) only sampled the northern hemisphere this variability was initially believed to be tied to solar drivers manifest in latitudinal variations in the thermal structure of the upper atmosphere. However, when Cassini delved into the southern hemisphere the latitudinal dependence was not present in the data. Recently, Westlake et al. (2011) showed that the pass-by-pass variability is correlated with the deviations in the plasma environment as identified by Rymer et al. (2009) and Simon et al. (2010). Furthermore, the studies of Westlake et al. (2011) and Bell et al. (2011) showed that Titan’s upper atmosphere responds to changes in the ambient magnetospheric plasma on timescales of roughly one Titan day (16 Earth days). We report on recent studies of energy deposition in Titan’s upper atmosphere. Previous studies by Smith et al. (2009), Cravens et al. (2008), Tseng et al. (2008), and Shah et al. (2009) reported on energetic proton and oxygen ion precipitation. Back of the envelope calculations by Sittler et al. (2009) showed that magnetospheric energy inputs are expected to be of the order of or greater than the solar processes. We report on further analysis of the plasma environment around Titan during the flybys that the INMS has good data. We utilize data from the Magnetospheric Imaging Instrument to determine how the magnetospheric particle population varies from pass to pass and how this influences the net magnetospheric energy input prior to the flyby. We also report on enhanced energetic neutral atom emissions during select highly energetic passes. References: Bell, J., et al.: “Simulating the time-dependent response of Titan's upper atmosphere to periods of magnetospheric forcing”. Geophys. Res. Lett., Vol. 38, L06202, 2011. Rymer, A. M., et al.: “Discrete classification and electron

  20. Observation of energetic-ion losses induced by various MHD instabilities in the Large Helical Device (LHD)

    SciTech Connect

    Ogawa, K.; Isobe, M.; Toi, K.; Watanabe, F.; Spong, Donald A; Shimizu, A.; Osakabe, M.; Ohdachi, S.; Sakakibara, S.

    2010-01-01

    Energetic-ion losses induced by toroidicity-induced Alfven eigenmodes (TAEs) and resistive interchange modes (RICs) were observed in neutral-beam heated plasmas of the Large Helical Device (LHD) at a relatively low toroidal magnetic field level (<= 0.75 T). The energy and pitch angle of the lost ions are detected using a scintillator-based lost-fast ion probe. Each instability increases the lost ions having a certain energy/pitch angle. TAE bursts preferentially induce energetic beam ions in co-passing orbits having energy from the injection energy E = 190keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down to similar to 130 keV in passing-toroidally trapped boundary orbits. Loss fluxes induced by these instabilities increase with different dependences on the magnetic fluctuation amplitude: nonlinear and linear dependences for TAEs and RICs, respectively.

  1. Role of Alfvén Instabilities in Energetic Ion Transport

    SciTech Connect

    Bell, M.G.; Bernabei, S.; Budny, R.; Darrow, D.; Fredrickson, E.D.; et al.

    1998-11-01

    Experiments of plasma heating at the ion cyclotron resonance of a minority specie have shown that the heating efficiency degrades above a certain power threshold. It is found that this threshold is due to the destabilization of a branch of shear Alfvén waves which causes a diffusive loss of fast ions, the Energetic Particle Modes. These modes not only play a fundamental role in the transport of the fast ions, but appear closely related to the formation of the giant sawteeth.

  2. Role of Alfv{acute e}n instabilities in energetic ion transport

    SciTech Connect

    Bernabei, S.; Bell, M.G.; Budny, R.; Darrow, D.; Fredrickson, E.D.; Gorelenkov, N.; Hosea, J.C.; Majeski, R.; Mazzucato, E.; Nazikian, R.; Phillips, C.K.; Rogers, J.H.; Schilling, G.; White, R.; Wilson, J.R.; Zonca, F.; Zweben, S.

    1999-05-01

    Experiments with plasma heating by waves at the ion cyclotron resonance of a minority species have shown that the heating efficiency degrades above a certain power threshold. It is found that this threshold is due to the destabilization of a branch of shear Alfv{acute e}n waves, the Energetic Particle Modes, which causes a diffusive loss of fast ions. These modes not only play a fundamental role in the transport of the fast ions, but appear closely related to the formation of giant sawteeth. {copyright} {ital 1999 American Institute of Physics.}

  3. Solar Energetic Particle Research within SEPServer - a Space Weather Perspective

    NASA Astrophysics Data System (ADS)

    Malandraki, O. E.

    2012-04-01

    SEPServer is a three year collaborative project funded by the seventh framework programme (FP7-SPACE) of the European Union. One of the primary goals of the project is to lead to novel knowledge on the source, acceleration and transport of Solar Energetic Particles (SEPs) during solar eruptions, a topic directly related to progress on Space Weather. This latter goal will be accomplished by both the extensive data analysis of energetic particle measurements hosted at SEPServer and the simulation-based data analysis methods capable of deconvolving the effects of interplanetary transport and solar injection from SEP observations. SEPServer focuses on the implementation of a comprehensive and up to date SEP event analysis service including scientific data driven analysis both for 1 AU and for > 1 AU using data from the SOHO/ERNE, SOHO/EPHIN, ACE/EPAM, ACE/SIS, WIND/3DP, Ulysses/HISCALE, Ulysses/COSPIN/LET, Ulysses/COSPIN/KET, STEREO/LET and STEREO/SEPT experiments. SEPServer will also provide for the first time the release of the HELIOS data set in a reasonable format and in full time resolution, thus making available data also for orbits inside 1 AU (down to 0.3 AU). During the first year of the project a novel SEP event list, including 114 cases, based on SOHO/ERNE high energy protons (~70 MeV) was produced. In parallel, the systematic scanning of electrons from SOHO/EPHIN (0.25-3.0 MeV) and ACE/EPAM (45-312 keV) was also performed for all SEP cases. The corresponding EM emissions were also delivered and catalogued. Plots of SEP fluxes for electrons and ions in different energy channels from different instruments (SOHO/ERNE, SOHO/EPHIN, ACE/EPAM), onset time determination and time shifting analysis for the identification of the solar release times of electrons from SOHO/EPHIN and ACE/EPAM, and velocity dispersion analysis of protons observed by SOHO/ERNE were performed, together with a first comparison with the associated solar electromagnetic emissions. SEPServer is

  4. Energetic particle physics in fusion research in preparation for burning plasma experiments

    NASA Astrophysics Data System (ADS)

    Gorelenkov, N. N.; Pinches, S. D.; Toi, K.

    2014-12-01

    The area of energetic particle (EP) physics in fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by Heidbrink and Sadler (1994 Nucl. Fusion 34 535). That review coincided with the start of deuterium-tritium (DT) experiments on the Tokamak Fusion Test Reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the ‘sea’ of Alfvén eigenmodes (AEs), in particular by the toroidicity-induced AE (TAE) modes and reversed shear AEs (RSAEs). In the present paper we attempt a broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices. Introductory discussions on the basic ingredients of EP physics, i.e., particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others, are given to help understanding of the advanced topics of EP physics. At the end we cover important and interesting physics issues related to the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

  5. Energetic Particle Physics In Fusion Research In Preparation For Burning Plasma Experiments

    SciTech Connect

    Gorelenkov, Nikolai N

    2013-06-01

    The area of energetic particle (EP) physics of fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by W.W. Heidbrink and G.J. Sadler [1]. That review coincided with the start of deuterium-tritium (DT) experiments on Tokamak Fusion Test reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the "sea" of Alfven eigenmodes (AE) in particular by the toroidicityinduced AEs (TAE) modes and reversed shear Alfven (RSAE). In present paper we attempt a broad review of EP physics progress in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus) including helical/stellarator devices. Introductory discussions on basic ingredients of EP physics, i.e. particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others are given to help understanding the advanced topics of EP physics. At the end we cover important and interesting physics issues toward the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

  6. Collective Temperature Anisotropy Instabilities in Intense Charged Particle Beams

    NASA Astrophysics Data System (ADS)

    Startsev, Edward

    2006-10-01

    Periodic focusing accelerators, transport systems and storage rings have a wide range of applications ranging from basic scientific research in high energy and nuclear physics, to applications such as ion-beam-driven high energy density physics and fusion, and spallation neutron sources. Of particular importance at the high beam currents and charge densities of practical interest, are the effects of the intense self fields produced by the beam space charge and current on determining the detailed equilibrium, stability and transport properties. Charged particle beams confined by external focusing fields represent an example of nonneutral plasma. A characteristic feature of such plasmas is the non-uniformity of the equilibrium density profiles and the nonlinearity of the self fields, which makes detailed analytical investigation very difficult. The development and application of advanced numerical tools such as eigenmode codes [1] and Monte-Carlo particle simulation methods [2] are often the only tractable approach to understand the underlying physics of different instabilities familiar in electrically neutral plasmas which may cause a degradation in beam quality. Two such instabilities are the electrostatic Harris instability [2] and the electromagnetic Weibel instability [1], both driven by a large temperature anisotropy which develops naturally in accelerators. The beam acceleration causes a large reduction in the longitudinal temperature and provides the free energy to drive collective temperature anisotropy instabilities. Such instabilities may lead to an increase in the longitudinal velocity spread, which will make focusing the beam difficult, and may impose a limit on the beam luminosity and the minimum spot size achievable in focusing experiments. This paper reviews recent advances in the theory and simulation of collective instabilities in intense charged particle beams caused by temperature anisotropy. We also describe new simulation tools that have been

  7. M3D-K simulations of sawteeth and energetic particle transport in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Shen, Wei; Fu, G. Y.; Sheng, Zheng-Mao; Breslau, J. A.; Wang, Feng

    2014-09-01

    Nonlinear simulations of sawteeth and related energetic particle transport are carried out using the kinetic/magnetohydrodynamic (MHD) hybrid code M3D-K. MHD simulations show repeated sawtooth cycles for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in the plasma core, depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with existing theories. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases with increasing particle energy.

  8. M3D-K Simulations of Sawteeth and Energetic Particle Transport in Tokamak Plasmas

    NASA Astrophysics Data System (ADS)

    Shen, Wei; Fu, Guoyong; Sheng, Zhengmao; Breslau, Joshua; Wang, Feng

    2013-10-01

    Nonlinear simulations of Sawteeth and energetic particle transport are carried out using the kinetic/MHD hybrid code M3D-K. MHD simulations show repeated sawtooth cycles due to a resistive (1,1) internal kink mode for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in plasma core depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with previous theory. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases as particle energy becomes large.

  9. M3D-K simulations of sawteeth and energetic particle transport in tokamak plasmas

    SciTech Connect

    Shen, Wei; Sheng, Zheng-Mao; Fu, G. Y.; Breslau, J. A.; Wang, Feng

    2014-09-15

    Nonlinear simulations of sawteeth and related energetic particle transport are carried out using the kinetic/magnetohydrodynamic (MHD) hybrid code M3D-K. MHD simulations show repeated sawtooth cycles for a model tokamak equilibrium. Furthermore, test particle simulations are carried out to study the energetic particle transport due to a sawtooth crash. The results show that energetic particles are redistributed radially in the plasma core, depending on pitch angle and energy. For trapped particles, the redistribution occurs for particle energy below a critical value in agreement with existing theories. For co-passing particles, the redistribution is strong with little dependence on particle energy. In contrast, the redistribution level of counter-passing particles decreases with increasing particle energy.

  10. EDITORIAL: Special issue containing papers presented at the 11th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems Special issue containing papers presented at the 11th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems

    NASA Astrophysics Data System (ADS)

    Kolesnichenko, Ya.

    2010-08-01

    The history of fusion research resembles the way in which one builds skyscrapers: laying the first foundation stone, one thinks about the top of the skyscraper. At the early stages of fusion, when it became clear that the thermonuclear reactor would operate with DT plasma confined by the magnetic field, the study of the `top item'—the physics of 3.5 MeV alpha particles produced by the DT fusion reaction—was initiated. The first publications on this topic appeared as long ago as the 1960s. At that time, because the physics of alpha particles was far from the experimental demand, investigations were carried out by small groups of theoreticians who hoped to discover important and interesting phenomena in this new research area. Soon after the beginning of the work, theoreticians discovered that alpha particles could excite various instabilities in fusion plasmas. In particular, at the end of the 1960s an Alfvén instability driven by alpha particles was predicted. Later it turned out that a variety of Alfvén instabilities with very different features does exist. Instabilities with perturbations of the Alfvénic type play an important role in current experiments; it is likely that they will affect plasma performance in ITER and future reactors. The first experimental manifestation of instabilities excited by superthermal particles in fusion devices was observed in the PDX tokamak in 1983. In this device a large-scale instability—the so called `fishbone instability'—associated with ions produced by the neutral beam injection resulted in a loss of a large fraction of the injected energy. Since then, the study of energetic-ion-driven instabilities and the effects produced by energetic ions in fusion plasmas has attracted the growing attention of both experimentalists and theorists. Recognizing the importance of this topic, the first conference on fusion alpha particles was held in 1989 in Kyiv under the auspices of the IAEA. The meeting in Kyiv and several

  11. Streaming reversal of energetic particles in the magnetotail during a substorm

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.; Williams, D. J.; Eastman, T. E.; Frank, L. A.; Akasofu, S.-I.

    1984-01-01

    A case of reversal in the streaming anisotropy of energetic ions and in the plasma flow observed from the IMP 8 spacecraft during a substorm on February 8, 1978 is studied in detail using measurements of energetic particles, plasma, and magnetic field. Four new features emerge when high time resolution data are examined in detail. The times of streaming reversal of energetic particles in different energy ranges do not coincide with the time of plasma flow reversal. Qualitatively different velocity distributions are observed in earthward and tailward plasma flows during the observed flow reversal intervals. Strong tailward streaming of energetic particles can be detected during northward magnetic field environments and, conversely, earthward streaming in southward field environments. During the period of tailward streaming of energetic particles, earthward streaming fluxes are occasionally detected.

  12. Energetic Particle Abundances as Probes of an Interplanetary Shock Wave

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Tylka, A. J.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We examine the unique abundance variations of Fe/O and He/H in solar energetic particles from a W09 event of 2001 April 10, that have leaked through the flank of an interplanetary shock launched from W04 on April 9. Shock waves from both events reach the Wind spacecraft on April 11. During the second event, both Fe/O and He/H begin at low values and rise to maxima near the time of passage of the shock waves, indicating greater scattering for the species with the highest rigidity at a given velocity. Strong modulation of Fe/O suggests preferential scattering and trapping of Fe by the wave spectrum near and behind the intermediate shock. A significant factor may be the residual proton-generated waves from the very hard proton spectrum accelerated by the early shock wave prior to the onset of the second event. Thus, ion abundances from the later event probe the residual wave spectrum at the earlier shock.

  13. Energetic Particle-Driven ULF Waves in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Yeoman, T. K.; James, M. K.; Klimushkin, D. Yu.; Mager, P. N.

    2016-02-01

    Ionospheric radar systems have proved to be a powerful tool for the investigation of magnetospheric ULF waves. High-m poloidal waves become much more attenuated in ground magnetometer data than low-m toroidal waves. For this reason ionospheric radar systems have been effective in the study of high-m poloidal waves driven by energetic particle populations within the magnetosphere, and it is this class of ULF waves that is discussed in this chapter. More recent ionospheric observations of high-m ULF waves have taken advantage of the Super Dual Auroral Radar Network (SuperDARN). SuperDARN is a global array of high-frequency (HF) radars. In a Doppler sounder, use is made of the direct reflection of a radio wave from the ionosphere, rather than a scattering process. A number of alternative techniques are available for exploring the ionospheric signatures of such wave events, which are relatively underexploited, and have the potential to provide important new observations.

  14. Enhancements of energetic particles near the heliospheric termination shock.

    PubMed

    McDonald, Frank B; Stone, Edward C; Cummings, Alan C; Heikkila, Bryant; Lal, Nand; Webber, William R

    2003-11-01

    The spacecraft Voyager 1 is at a distance greater than 85 au from the Sun, in the vicinity of the termination shock that marks the abrupt slowing of the supersonic solar wind and the beginning of the extended and unexplored distant heliosphere. This shock is expected to accelerate 'anomalous cosmic rays', as well as to re-accelerate Galactic cosmic rays and low-energy particles from the inner Solar System. Here we report a significant increase in the numbers of energetic ions and electrons that persisted for seven months beginning in mid-2002. This increase differs from any previously observed in that there was a simultaneous increase in Galactic cosmic ray ions and electrons, anomalous cosmic rays and low-energy ions. The low-intensity level and spectral energy distribution of the anomalous cosmic rays, however, indicates that Voyager 1 still has not reached the termination shock. Rather, the observed increase is an expected precursor event. We argue that the radial anisotropy of the cosmic rays is expected to be small in the foreshock region, as is observed. PMID:14603312

  15. Elemental composition of solar energetic particles. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Cook, W. R., III

    1981-01-01

    The Low Energy Telescopes on the Voyager spacecraft are used to measure the elemental composition (2 or = Z or = 28) and energy spectra (5 to 15 MeV/nucleon) of solar energetic particles (SEPs) in seven large flare events. Four flare events are selected which have SEP abundance ratios approximately independent of energy/nucleon. The abundances for these events are compared from flare to flare and are compared to solar abundances from other sources: spectroscopy of the photosphere and corona, and solar wind measurements. The four flare average SEP composition is significantly different from the solar composition determined by photospheric spectroscopy. The average SEP composition is in agreement with solar wind abundance results and with a number of recent coronal abundance measurements. The evidence for a common depletion of oxygen in SEPs, the corona and the solar wind relative to the photosphere suggest that the SEPs originate in the corona and that both the SEPs and solar wind sample a coronal composition which is significantly and persistently different from that of the photosphere.

  16. Factors Affecting the Intensity of Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk

    2011-01-01

    This paper updates the influence of environmental and source factors of shocks driven by coronal mass ejections (CMEs) that are likely to influence the solar energetic particle (SEP) events. The intensity variation due to CME interaction reported that is confirmed by expanding the investigation to all the large SEP events of solar cycle 23. The large SEP events are separated into two groups, one associated with CMEs running into other CMEs, and the other with CMEs running into the ambient solar wind. SEP events with CME interaction generally have a higher intensity. New possibilities such as the influence of coronal holes on the SEP intensity are also discussed. For example, the presence of a large coronal hole between a well-connected eruption and the solar disk center may render the shock poorly connected because of the interaction between the CME and the coronal hole. This point is illustrated using the 2004 December 3 SEP event delayed by about 12 hours from the onset of the associated CME. There is no other event at the Sun that can be associated with the SEP onset. This event is consistent with the possibility that the coronal hole interaction influences the connectivity of the CMEs that produce SEPs, and hence the intensity of the SEP event.

  17. Solar Energetic Particle Events in Different Types of Solar Wind

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Vourlidas, A.

    2014-08-01

    We examine statistically some properties of 96 20 MeV gradual solar energetic proton (SEP) events as a function of three different types of solar wind (SW) as classified by Richardson and Cane. Gradual SEP (E > 10 MeV) events are produced in shocks driven by fast (V >~ 900 km s-1) and wide (W > 60°) coronal mass ejections (CMEs). We find no differences among the transient, fast, and slow SW streams for SEP 20 MeV proton event timescales. It has recently been found that the peak intensities Ip of these SEP events scale with the ~2 MeV proton background intensities, which may be a proxy for the near-Sun shock seed particles. Both the intensities Ip and their 2 MeV backgrounds are significantly enhanced in transient SW compared to those of fast and slow SW streams, and the values of Ip normalized to the 2 MeV backgrounds only weakly correlate with CME V for all SW types. This result implies that forecasts of SEP events could be improved by monitoring both the Sun and the local SW stream properties and that the well known power-law size distributions of Ip may differ between transient and long-lived SW streams. We interpret an observed correlation between CME V and the 2 MeV background for SEP events in transient SW as a manifestation of enhanced solar activity.

  18. Solar Energetic Particle Events in Different Types of Solar Wind

    NASA Astrophysics Data System (ADS)

    Kahler, Stephen W.; Vourlidas, Angelos

    2014-06-01

    We examine statistically some properties of 96 20 MeV gradual solar energetic proton (SEP) events as a function of three different types of solar winds (SWs) as classified by Richardson and Cane (2012). Gradual SEP (E > 10 MeV) events are produced in shocks driven by fast (V > 900 km/s) and wide (W > 60 deg) coronal mass ejections (CMEs). We find no differences between transient and fast or slow SW streams for SEP 20-MeV event timescales. It has recently been found that the peak intensities Ip of these SEP events scale with the ~ 2 MeV proton background intensities, which may be a proxy for the near-Sun shock seed particles. Both the intensities Ip and their 2 MeV backgrounds are significantly enhanced in transient SW compared to those of fast and slow SW streams, and the values of Ip normalized to the 2 MeV backgrounds only weakly correlate with CME V for all SW types. This result implies that forecasts of SEP events could be improved by monitoring both the Sun and the local SW stream properties and that the well known power-law size distributions of Ip may differ between transient and long-lived SW streams. We interpret an observed correlation between CME V and the 2 MeV background for SEP events in transient SW as a manifestation of enhanced solar activity.

  19. The Origin of Element Abundance Variations in Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Reames, Donald V.

    2016-08-01

    Abundance enhancements, during acceleration and transport in both gradual and impulsive solar energetic particle (SEP) events, vary approximately as power laws in the mass-to-charge ratio [A/Q] of the ions. Since the Q-values depend upon the electron temperature of the source plasma, this has allowed a determination of this temperature from the pattern of element-abundance enhancements and a verification of the expected inverse-time dependence of the power of A/Q for diffusive transport of ions from the SEP events, with scattering mean free paths found to be between 0.2 and 1 AU. SEP events derived from plasma of different temperatures map into different regions in typical cross-plots of abundances, spreading the distributions. In comparisons of SEP events with temperatures above 2 MK, impulsive events show much broader non-thermal variation of abundances than do gradual events. The extensive shock waves accelerating ions in gradual events may average over much of an active region where numerous but smaller magnetic reconnections, "nanojets", produce suprathermal seed ions, thus averaging over varying abundances, while an impulsive SEP event only samples one local region of abundance variations. Evidence for a reference He/O-abundance ratio of 91, rather than 57, is also found for the hotter plasma. However, while this is similar to the solar-wind abundance of He/O, the solar-wind abundances otherwise provide an unacceptably poor reference for the SEP-abundance enhancements, generating extremely large errors.

  20. The Impact of Energetic Particle Precipitation on the Earths Atmosphere

    NASA Astrophysics Data System (ADS)

    Funke, B.; López-Puertas, M.; García-Comas, M.; Bermejo-Pantaleón, D.; Stiller, G. P.; von Clarmann, T.

    Energetic particle precipitation (EPP) represents an important Sun-Earth coupling mechanism with important implications on polar stratospheric ozone chemistry. Solar protons generated during solar storms cause sporadically in situ production of stratospheric NO x and HO x radicals involved in catalytic ozone destruction. Further, NO produced continuously in the mesosphere and lower thermosphere by medium energy electron precipitation (EEP) descends to the stratosphere during the polar winter, where it represents an additional, though variable source of NO x . The capability of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) to measure all important NO y species, as well as ClO and HOCl with global coverage including the polar night regions make it an ideal instrument for studying EPP effects on stratospheric chemistry. We present a quantitative assessment of EPP-induced composition changes as observed by MIPAS during 2002-2004, including the unusually strong solar proton event in October/November 2003. The impact of EPP on the stratospheric ozone budget has been studied with chemical models. The stratospheric ozone loss in the polar regions reached 18DU and lasted over months to years.

  1. Solar energetic particle events in different types of solar wind

    SciTech Connect

    Kahler, S. W.; Vourlidas, A.

    2014-08-10

    We examine statistically some properties of 96 20 MeV gradual solar energetic proton (SEP) events as a function of three different types of solar wind (SW) as classified by Richardson and Cane. Gradual SEP (E > 10 MeV) events are produced in shocks driven by fast (V ≳ 900 km s{sup –1}) and wide (W > 60°) coronal mass ejections (CMEs). We find no differences among the transient, fast, and slow SW streams for SEP 20 MeV proton event timescales. It has recently been found that the peak intensities Ip of these SEP events scale with the ∼2 MeV proton background intensities, which may be a proxy for the near-Sun shock seed particles. Both the intensities Ip and their 2 MeV backgrounds are significantly enhanced in transient SW compared to those of fast and slow SW streams, and the values of Ip normalized to the 2 MeV backgrounds only weakly correlate with CME V for all SW types. This result implies that forecasts of SEP events could be improved by monitoring both the Sun and the local SW stream properties and that the well known power-law size distributions of Ip may differ between transient and long-lived SW streams. We interpret an observed correlation between CME V and the 2 MeV background for SEP events in transient SW as a manifestation of enhanced solar activity.

  2. The Origin of Element Abundance Variations in Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Reames, Donald V.

    2016-07-01

    Abundance enhancements, during acceleration and transport in both gradual and impulsive solar energetic particle (SEP) events, vary approximately as power laws in the mass-to-charge ratio [ A/Q] of the ions. Since the Q-values depend upon the electron temperature of the source plasma, this has allowed a determination of this temperature from the pattern of element-abundance enhancements and a verification of the expected inverse-time dependence of the power of A/Q for diffusive transport of ions from the SEP events, with scattering mean free paths found to be between 0.2 and 1 AU. SEP events derived from plasma of different temperatures map into different regions in typical cross-plots of abundances, spreading the distributions. In comparisons of SEP events with temperatures above 2 MK, impulsive events show much broader non-thermal variation of abundances than do gradual events. The extensive shock waves accelerating ions in gradual events may average over much of an active region where numerous but smaller magnetic reconnections, "nanojets", produce suprathermal seed ions, thus averaging over varying abundances, while an impulsive SEP event only samples one local region of abundance variations. Evidence for a reference He/O-abundance ratio of 91, rather than 57, is also found for the hotter plasma. However, while this is similar to the solar-wind abundance of He/O, the solar-wind abundances otherwise provide an unacceptably poor reference for the SEP-abundance enhancements, generating extremely large errors.

  3. {Interball-1 Plasma, Magnetic Field, and Energetic Particle Observations}

    NASA Technical Reports Server (NTRS)

    Sibeck, David G.

    1998-01-01

    Funding from NASA was received in two installments. The first installment supported research using Russian/Czech/Slovak/French Interball-1 plasma, magnetic field, and energetic particles observations in the vicinity of the magnetopause. The second installment provided salary support to review unsolicited proposals to NASA for data recovery and archiving, and also to survey ISTP data provision efforts. Two papers were published under the auspices of the grant. Sibeck et al. reported Interball-1 observations of a wave on the magnetopause with an amplitude in excess of 5 R(sub E), the largest ever reported to date. They attributed the wave to a hot flow anomaly striking the magnetopause and suggested that the hot flow anomaly itself formed during the interaction of an IMF discontinuity with the bow shock. Nemecek et al. used Interball-1's VDP Faraday cup to identify large transient increases in the magnetosheath density. They noted large variations in simultaneous Wind observations of the IMF cone angle, but were unable to establish any relationship between the cone angle variations at Wind and the density variations at Interball-1. Funds from the second installment were used to review over 20 proposals from various researchers in the scientific community who sought NASA support to restore or archive past observations. It also supported a survey of ISTP data provisions which was used as input to a Senior Review of ongoing NASA ISTP programs.

  4. Associations of Accelerating CMEs with Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Kahler, S.; Sheeley, N.; Reames, D.

    2001-05-01

    Gradual solar energetic particle (SEP) events are well associated with fast coronal mass ejections (CMEs). The times of significant E > 10 MeV SEP events observed with the Goddard Space Flight Center EPACT detector on the Wind spacecraft have been compared with CME observations from the Lasco coronagraph on the SOHO spacecraft. As earlier studies have shown, a correlation exists between peak SEP intensities and the measured speeds of associated CMEs. Of the CMEs associated with SEP events in the period 1996 to 2000, we find 9 CMEs for which the height-time plots of the leading edges show accelerations of at least 13 m/s/s. The heights at which those CMEs attained speeds of 600 km/s ranged from 7 to 20 Ro. The peak 20 MeV intensities of the 9 SEP events are relatively low compared with all gradual SEP events of the same period. We compare the energy spectra and solar event associations of these 9 SEP events with those of the SEP events associated with CMEs of uniform speeds.

  5. Acceleration of Solar Energetic Particle by CME induced shocks

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Chun; Liou, Kan; Dryer, Murray; Wu, Shitsan; Tylka, Allan J.

    Solar Energetic Particles (SEPs) may play a major role on the Space Weather forecast since it only takes about 8 minutes (for an representative ion accelerated to 0.5c at a shock's COBPoint at roughly 0.5 AU) to propagate from the Sun to the Earth. COBPoint means Connection of interplanetary magnetic field (IMF) with Observer Point. It is well known that SEPs can be generated by interplanetary (IP) shocks which are driven by the coronal mass ejections (CMEs). Using both a 1.5D magnetohydrodynamic simulation and ACE's EPAM data analysis, "how SEPs are being accelerated by IP shocks?" will be presented. Three SEP events occurred during Halloween 2003 epoch will be presented in this study. We assume that the flares occur close enough to the the ecliptic plane to justify the use of the 1.5D approximation and, thus, the IMF connection from the shocks' COBPoint to ACE. We also assume, as a further "first-look" approximation, that the COBPoint is always on the Sun-Earth line. The correlation coefficient for "IP shock Mach number" vs. "SEPs enhancement" will be calculated to interpret "how SEPs are generated by IP shocks?" thus supporting the empirical and existing discussion concerning the need for a high shock compression ratio.

  6. Sheath dynamics and energetic particle distributions on substrates

    NASA Astrophysics Data System (ADS)

    Lieberman, Michael A.

    2009-10-01

    The energy and angular distributions (EAD's) of energetic particles arriving at a substrate determine crucial plasma processing characteristics; thus knowledge and control of the EAD's are vital for nanoelectronics design and fabrication during scale-down to the ultimate 4--6 nm transistor gate lengths over the next 15 years. We review the history and state-of-the-art of measurements, simulations, and analyses of ion, fast neutral, and ballistic electron EAD's. Ion measurements have been made using electrostatic energy analyzers, cylindrical mirror analyzers, and retarding grid analyzers, often now coupled with quadrupole mass spectrometers to compare different ions in the same discharge. The state-of-the-art for capacitive rf sheaths has advanced greatly since the first observation of a bi-modal ion energy distribution (IED) over 50 years ago. More recently, measurement techniques and models have been developed to determine fast neutral distributions. Monte Carlo, and particle-in-cell simulations with Monte Carlo collisions (PIC-MCC) have been used to study IED's since the late 1980's. Recently, PIC-MCC simulations were used to obtain ballistic electron EAD's. Analytical models of the IED for collisionless rf sheaths have emphasized the role of τi/τrf, the ratio of ion transit time across the sheath to rf period, with separate models for the low and high frequency regimes. Various simplifications and bridging models now exist. For collisional rf sheaths, the important role of λi/s, the ratio of ion-neutral mean free path to sheath width, in modifying the collisionless bi-modal IED was demonstrated in the early 1990's. Surface charging effects on insulating substrates are important for low frequency rf discharges or for pulsed transient sheaths; the latter are found during plasma ion implantation processes. Analytical models of the IED for plasma ion implantation have been extended to insulating surfaces and compared with experimental results.

  7. Ionospheric Electric Field and Energetic Particles; Past Successes, Future Challenges

    NASA Astrophysics Data System (ADS)

    Rodger, A. S.

    2005-12-01

    The International Geophysical Year (1957-58) saw a step-increase in the number of ionospheric observations in both polar regions and the establishment of the World Data Centres allowing free exchange of information. Exploitation of these data from such networks of observatories, combined with the early satellite measurements, demonstrated that electric fields and energetic particles driven by solar wind-magnetosphere interactions are of paramount importance in determining the structure and dynamics of the high-latitude ionosphere. Over the next five decades, much greater understanding of the interactions of the solar wind-magnetosphere-ionosphere system has been achieved. Many features and phenomena can now be predicted with a good degree of accuracy, given the initial solar wind conditions. A few scientific milestones will be presented, many of which have resulted from technical innovations, such as coherent and incoherent radars, and optical imaging. The International Heliophysical and Polar Years offer an excellent opportunity to address the outstanding issues of geospace research. Specific examples will be described. These include the spatial and temporal deposition of energy into the ionosphere and thermosphere by particles and electric fields both on the day side and nightside as a result of reconnection and substorms, and the interaction of micro-scale processes on the meso and macro-scale structure of the coupled system. Such complex topics can now be addressed for the first time with the enhanced capabilities of the ground-based networks of observatories, well complemented by remote sensing from satellites. The outcome will be much improved understanding of the closely-coupled SW-M-I-T system and hence better predictions both for space weather and Sun-Earth connections.

  8. SOLAR ENERGETIC PARTICLE EVENTS AND THE KIPLINGER EFFECT

    SciTech Connect

    Kahler, S. W.

    2012-03-01

    The Kiplinger effect is an observed association of solar energetic (E > 10 MeV) particle (SEP) events with a 'soft-hard-harder' (SHH) spectral evolution during the extended phases of the associated solar hard (E > 30 keV) X-ray (HXR) flares. Besides its possible use as a space weather predictor of SEP events, the Kiplinger effect has been interpreted as evidence of SEP production in the flare site itself, contradicting the widely accepted view that particles of large SEP events are predominately or entirely accelerated in shocks driven by coronal mass ejections (CMEs). We review earlier work to develop flare soft X-ray (SXR) and HXR spectra as SEP event forecast tools and then examine recent Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) evidence supporting the association of SHH HXR flares with large SEP events. We point out that ad hoc prediction criteria using the CME widths and SXR flare durations of associated RHESSI hard X-ray bursts (HXBs) can yield results comparable to those of the SHH prediction criteria. An examination of the RHESSI dynamic plots reveals several ambiguities in the determination of whether and when the SHH criteria are fulfilled, which must be quantified and applied consistently before an SHH-based predictive tool can be made. A comparative HXR spectral study beginning with the large population of relatively smaller SEP events has yet to be done, and we argue that those events will not be so well predicted by the SHH criteria. SHH HXR flares and CMEs are both components of large eruptive flare events, which accounts for the good connection of the SHH HXR flares with SEP events.

  9. Solar Energetic Particles within the STEREO era: 2007-2012

    NASA Astrophysics Data System (ADS)

    Papaioannou, A.; Malandraki, O. E.; Heber, B.; Dresing, N.; Klein, K. L.; Vainio, R.; Rodriguez-Gasen, R.; Klassen, A.; Gomez-Herrero, R.; Vilmer, N.; Mewaldt, R. A.; Tziotziou, K.; Tsiropoula, G.

    2013-09-01

    STEREO (Solar TErrestrial RElations Observatory) recordings provide an unprecedented opportunity to identify the evolution of Solar Energetic Particles (SEPs) at different observing points in the heliosphere, which is expected to provide new insight on the physics of solar particle genesis, propagation and acceleration as well as on the properties of the interplanetary magnetic field that control these acceleration and propagation processes. In this work, two instruments onboard STEREO have been used in order to identify all SEP events observed within the rising phase of solar cycle 24 from 2007 to 2011, namely: the Low Energy Telescope (LET) and the Solar Electron Proton Telescope (SEPT). A scan over STEREO/LET protons within the energy range 6-10 MeV has been performed for each of the two STEREO spacecraft. We have tracked all enhancements that have been observed above the background level of this particular channel and cross checked with available lists on STEREO/ICMEs, SIRs and shocks as well as with the reported events in literature. Furthermore, parallel scanning of the STEREO/SEPT electrons in order to pinpoint the presence (or not) of an electron event has been performed in the energy range of 55-85 keV, for all of the aforementioned proton events, included in our lists. We provide the onset of all events for both protons and electrons, time-shifting analysis for near relativistic electrons which lead to the inferred solar release time and the relevant solar associations from radio spectrographs (Nancay Decametric Array; STEREO/WAVES) to GOES Soft X-rays and coronal mass ejections spotted by both SOHO/LASCO and STEREO Coronographs

  10. Prediction of solar energetic particle event histories using real-time particle and solar wind measurements

    NASA Technical Reports Server (NTRS)

    Roelof, E. C.; Gold, R. E.

    1978-01-01

    The comparatively well-ordered magnetic structure in the solar corona during the decline of Solar Cycle 20 revealed a characteristic dependence of solar energetic particle injection upon heliographic longitude. When analyzed using solar wind mapping of the large scale interplanetary magnetic field line connection from the corona to the Earth, particle fluxes display an approximately exponential dependence on heliographic longitude. Since variations in the solar wind velocity (and hence the coronal connection longitude) can severely distort the simple coronal injection profile, the use of real-time solar wind velocity measurements can be of great aid in predicting the decay of solar particle events. Although such exponential injection profiles are commonplace during 1973-1975, they have also been identified earlier in Solar Cycle 20, and hence this structure may be present during the rise and maximum of the cycle, but somewhat obscured by greater temporal variations in particle injection.

  11. Using ACE and Ulysses to investigate the heliographic transport of energetic particles

    NASA Astrophysics Data System (ADS)

    Robinson, Ian M.

    2002-03-01

    The Advanced Composition Explorer (ACE) and the Ulysses spacecraft follow radically different trajectories, allowing the Sun to be simultaneously studied from 2 different perspectives. Data from the low energy particle instruments carried by these spacecraft reveals energetic particles accelerated at the Sun can access large angular extents of the interplanetary medium. We look at a rare case when the heliographic transport of energetic electrons was apparently prevented and speculate upon the ability of the corona to inhibit the propagation of these particles.

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

    PubMed

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

    1989-12-15

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

  13. Kelvin-Helmholtz instabilities with Godunov smoothed particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Cha, Seung-Hoon; Inutsuka, Shu-Ichiro; Nayakshin, Sergei

    2010-04-01

    Numerical simulations for the non-linear development of Kelvin-Helmholtz instability in two different density layers have been performed with the particle-based method (Godunov SPH) developed by Inutsuka. The Godunov SPH can describe the Kelvin-Helmholtz instability even with a high-density contrast, while the standard SPH shows the absence of the instability across a density gradient. The interaction of a dense blob with a hot ambient medium has been performed also. The Godunov SPH describes the formation and evolution of the fingers due to the combinations of Rayleigh-Taylor, Richtmyer-Meshkov and Kelvin-Helmholtz instabilities. The blob test result coincides well with the results of the grid-based codes. An inaccurate handling of a density gradient in the standard SPH has been pointed out as the direct reason of the absence of the instabilities. An unphysical force happens at the density gradient even in a pressure equilibrium, and repulses particles from the initial density discontinuity. Therefore, the initial perturbation damps, and a gap form at the discontinuity. The unphysical force has been studied in terms of the consistency of a numerical scheme. Contrary to the standard SPH, the momentum equation of the Godunov SPH does not use the particle approximation, and has been derived from the kernel convolution or a new Lagrangian function. The new Lagrangian function used in the Godunov SPH is more analogous to the real Lagrangian function for continuum. The momentum equation of the Godunov SPH has much better linear consistency, so the unphysical force is greatly reduced compared to the standard SPH in a high density contrast.

  14. Velocity space evolution of a minority energetic electron population undergoing the anomalous Doppler instability

    SciTech Connect

    Lai, W. N.; Chapman, S. C.; Dendy, R. O.

    2015-11-15

    The kinetic evolution in velocity space of a minority suprathermal electron population that is undergoing the anomalous Doppler instability (ADI) is investigated using the results from fully nonlinear numerical simulations that self-consistently evolve particles and fields in a plasma. Electron trajectories in phase space during different stages of the ADI are captured, and are analysed in relation to the characteristics of the excited electric fields and of the overall distribution of particles. For some electrons, trapping and mirroring effects are observed during the saturation phase. A relationship between the second order moments of the perpendicular electron distribution function and time is established, and is used to investigate the range of applicability of analytical approximations drawn from classical theory, that involve a quasilinear wave-driven diffusion operator.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  17. Long-Term Energetic-Particle Databases From Geosynchronous and GPS Orbits

    NASA Astrophysics Data System (ADS)

    Reedy, R. C.; Belian, R. D.; Cayton, T. E.; Henderson, M. G.; Ingraham, J. C.; Jahn, J.-M.; Mclachlan, P. S.; Meier, M. M.; Reeves, G. D.; Weiss, L. A.

    Since the Vela satellites, first launched in 1963, Los Alamos has had a number of instruments in space to measure energetic radiations from nuclear tests, such as x rays, neutrons, and gamma rays. It soon became clear that we also needed instruments dedicated to the study of the space environment, including energetic particles and the plasma. Energetic particles in space can induce some serious radiation effects in spacecraft. Electrons with energies above about 10 keV can charge the surfaces of spacecraft and change the surface potential. Relativistic electrons (energies greater than approx. 1 MeV) can penetrate deep into material and create hazardous deep dielectric charging. High fluxes of solar energetic particles can create anomalies in electronics and degrade the performance of solar panels and other spacecraft components. A good knowledge of the temporal and spatial variations of these energetic particles is needed in planning future spacecraft and in understanding the Earth's space environment. Energetic particle and plasma measurements by Los Alamos in space began with the second Vela satellite launch in 1963. Since then, Los Alamos has had energetic-particle instruments on twelve spacecraft at geosynchronous orbit since 1976 and on seven satellites of the Global Positioning System (GPS) since 1983. Data from these and other instruments, such as plasma analyzers, have been sent to Los Alamos for processing and analysis. Databases using these data have been or are being established at Los Alamos and are described here.

  18. Elemental composition of solar energetic particles in 1977 and 1978

    NASA Technical Reports Server (NTRS)

    Cook, W. R.; Stone, E. C.; Vogt, R. E.; Trainor, J. H.; Webber, W. R.

    1979-01-01

    The elemental composition of energetic nuclei from seven major solar flare events were measured wit the cosmic ray detector systems aboard the Voyager 1 and 2 spacecraft. The energetic nuclei abundances differ significantly from those of photospheric material. They are enhanced relative to the photonsphere by a factor which is the ratio of abundance of an energetic nuclei species (relative to oxygen) over the corresponding abundance of photospheric material. This factor is common to all events and has a nonmonochromatic characteristic dependence on nuclear charge. This factor is roughly ordered by first ionization potential into two groups of elements, metallics and volatiles.

  19. Heavy-Element Abundances in Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    2004-01-01

    We survey the relative abundances of elements with 1 less than or = Z less than or = 82 in solar energetic particle (SEP) events observed at 2 - 10 MeV amu" during nearly 9 years aboard the Wind spacecraft, with special emphasis on enhanced abundances of elements with 2Z greater than or = 34. Abundances of Fe/O again show a bimodal distribution with distinct contributions from impulsive and gradual SEP events as seen in earlier solar cycles. Periods with greatly enhanced abundances of (50 less than or = Z less than or = 56)/O, like those with enhanced He-3/He-4, fall prominently in the Fe-rich population of the impulsive SEP events. In a sample of the 39 largest impulsive events, 25 have measurable enhancements in (50 less than or = Z less than or = 56)/O and (76 less than or = Z less than or = 82)/O, relative to coronal values, ranging from approx. 100 to 10,000. By contrast, in a sample of 45 large gradual events the corresponding enhancements vary from approx. 0.2 to 20. However, the magnitude of the heavy-element enhancements in impulsive events is less striking than their strong correlation with the Fe spectral index and flare size, with the largest enhancements occurring in flares with the steepest Fe spectra, the smallest Fe fluence, and the lowest X-ray intensity, as reported here for the first time Thus it seem that small events with low energy input can produce only steep spectra of the dominant species but accelerate rare heavy elements with great efficiency, probably by selective absorption of resonant waves in the flare plasma. With increased energy input, enhancements diminish, as heavy ions are depleted, and spectra of the dominant species harden.

  20. Heavy-Element Abundances in Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Ng, C. K.

    2004-01-01

    We survey the relative abundances of elements with 1 < or equal to Z < or equal to 82 in solar energetic particle (SEP) events observed at 2-10 MeV/amu during nearly 9 years aboard the Wind spacecraft, with special emphasis on enhanced abundances of elements with Z > or equal to 34. Abundances of Fe/O again show a bimodal distribution with distinct contributions from impulsive and gradual SEP events as seen in earlier solar cycles. Periods with greatly enhanced abundances of (50 < or equal to Z < or equal to 56)/O, like those with enhanced (3)He/(4)He, fall prominently in the Fe-rich population of the impulsive SEP events. In a sample of the 39 largest impulsive events, 25 have measurable enhancements in (50 < or equal to z < or equal to 56)/O and (76 < or equal to Z < or equal to 82)/O, relative to coronal values, ranging from approx. 100 to 10,000. By contrast, in a sample of 45 large gradual events the corresponding enhancements vary from approx. 0.2 to 20. However, the magnitude of the heavy-element enhancements in impulsive events is less striking than their strong correlation with the Fe spectral index and flare size, with the largest enhancements occurring in flares with the steepest Fe spectra, the smallest Fe fluence, and the lowest X-ray intensity, as reported here for the first time. Thus it seems that small events with low energy input can produce only steep spectra of the dominant species but accelerate rare heavy elements with great efficiency, probably by selective absorption of resonant waves in the flare plasma. With increased energy input, enhancements diminish, as heavy ions are depleted, and spectra of the dominant species harden.

  1. Regimes of Pulsar Pair Formation and Particle Energetics

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; Muslimov, Alexander G.; Zhang, Bing; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We investigate the conditions required for the production of electron-positron pairs above a pulsar polar cap (PC) and the influence of pair production on the energetics of the primary particle acceleration. Assuming space-charge limited flow acceleration including the inertial frame-dragging effect, we allow both one-photon and two-photon pair production by either curvature radiation (CR) photons or photons resulting from inverse-Compton scattering of thermal photons from the PC by primary electrons. We find that,, while only the younger pulsars can produce pairs through CR, nearly all known radio pulsars are capable of producing pairs through non-resonant inverse-Compton scatterings. The effect of the neutron star equations of state on the pair death lines is explored. We show that pair production is facilitated in more compact stars and more a massive stars. Therefore accretion of mass by pulsars in binary systems may allow pair production in most of the millisecond purser population. We also find that two-photon pair production may be important in millisecond pursers if their surface temperatures are above approx. or equal to three million degrees K. Pursers that produce pairs through CRT wilt have their primary acceleration limited by the effect of screening of the electric field. In this regime, the high-energy luminosity should follow a L(sub HE) proportional to dot-E(sup 1/2, sub rot) dependence. The acceleration voltage drop in pursers that produce pairs only through inverse-Compton emission will not be limited by electric field screening. In this regime, the high-energy luminosity should follow a L(sub HE) proportional to dot-E(sub rot) dependence. Thus, older pursers will have significantly lower gamma-ray luminosity.

  2. Solar magnetic connections in gradual solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Kahler, S.; Arge, C.

    2003-04-01

    Gradual solar energetic particle (SEP) events are assumed to be produced in coronal and interplanetary shocks driven by fast coronal mass ejections (CMEs). Most of these SEP-associated fast CMEs are large in angular extent and intersect the ecliptic plane. In some cases, however, their angular extents lie completely outside the ecliptic plane. If we assume that the associated coronal shocks share the CME angular extents, the magnetic field lines connecting the Earth with the solar source surface (positioned at 2.5 Rs from Sun center) are confined to the ecliptic plane, and SEPs undergo no cross-field diffusion, then such SEP events should not be observed. One explanation for these observed SEP events is that the solar coronal connection of the field lines at Earth does not lie in the ecliptic plane in the solar coronal regions where shock acceleration takes place, which is thought to occur between ~2-10 Rs. To test this idea, the interplanetary magnetic field must be traced from Earth back to these coronal regions. A simple way to do this is to use the potential source surface and Schatten current sheet models in combination along with the assumption of constant solar wind flow speed along magnetic field lines. This approach allows interplanetary field lines to be traced from 1 AU back to coronal regions and therefore determine whether high latitudinal connections can explain the SEPs from high-latitude CMEs. We select Wind EPACT SEP events and associated narrow or high-latitude Lasco CMEs to test for high-latitude connections using the magnetic field model.

  3. Forecasting the Solar Drivers of Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Falconer, David A.; Moore, Ronald L.; Barghouty, Abdulnasser F.; Khazanov, Igor

    2012-01-01

    Large flares and fast CMEs are the drivers of the most severe space weather including Solar Energetic Particle Events (SEP Events). Large flares and their co-produced CMEs are powered by the explosive release of free magnetic energy stored in non-potential magnetic fields of sunspot active regions. The free energy is stored in and released from the low-beta regime of the active region's magnetic field above the photosphere, in the chromosphere and low corona. From our work over the past decade and from similar work of several other groups, it is now well established that (1) a proxy of the free magnetic energy stored above the photosphere can be measured from photospheric magnetograms, maps of the measured field in the photosphere, and (2) an active region's rate of production of major CME/flare eruptions in the coming day or so is strongly correlated with its present measured value of the free-energy proxy. These results have led us to use the large database of SOHO/MDI full-disk magnetograms spanning Solar Cycle 23 to obtain empirical forecasting curves that from an active region's present measured value of the free-energy proxy give the active region's expected rates of production of major flares, CMEs, fast CMEs, and SEP Events in the coming day or so (Falconer et al 2011, Space Weather, 9, S04003). We will present these forecasting curves and demonstrate the accuracy of their forecasts. In addition, we will show that the forecasts for major flares and fast CMEs can be made significantly more accurate by taking into account not only the value of the free energy proxy but also the active region's recent productivity of major flares; specifically, whether the active region has produced a major flare (GOES class M or X) during the past 24 hours before the time of the measured magnetogram.

  4. Interplanetary particle transport simulation for warning system for aviation exposure to solar energetic particles

    NASA Astrophysics Data System (ADS)

    Kubo, Yûki; Kataoka, Ryuho; Sato, Tatsuhiko

    2015-07-01

    Solar energetic particles (SEPs) are one of the extreme space weather phenomena. A huge SEP event increases the radiation dose received by aircrews, who should be warned of such events as early as possible. We developed a warning system for aviation exposure to SEPs. This article describes one component of the system, which calculates the temporal evolution of the SEP intensity and the spectrum immediately outside the terrestrial magnetosphere. To achieve this, we performed numerical simulations of SEP transport in interplanetary space, in which interplanetary SEP transport is described by the focused transport equation. We developed a new simulation code to solve the equation using a set of stochastic differential equations. In the code, the focused transport equation is expressed in a magnetic field line coordinate system, which is a non-orthogonal curvilinear coordinate system. An inverse Gaussian distribution is employed as the injection profile of SEPs at an inner boundary located near the Sun. We applied the simulation to observed SEP events as a validation test. The results show that our simulation can closely reproduce observational data for the temporal evolution of particle intensity. By employing the code, we developed the WArning System for AVIation Exposure to Solar energetic particles (WASAVIES).

  5. Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

    SciTech Connect

    Fu, G.Y.; Cheng, C.Z.

    1992-07-01

    The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal MHD solution as the lowest order eigenfunction. The finite Larmor radius (FLR) effects and the finite drift orbit width (FDW) effects are included for both circulating and trapped energetic particles. It is shown that, for circulating particles, FLR and FDW effects have two opposite influences on the stability of the high-n TAE modes. First, they have the usual stabilizing effects by reducing the wave particle interaction strength. Second, they also have destabilizing effects by allowing more particles to resonate with the TAE modes. It is found that the growth rate induced by the circulating alpha particles increase linearly with toroidal mode number n for small {kappa}{sub {theta}}{rho}{sub {alpha}}, and decreases as 1/n for {kappa}{sub {theta}}{rho}{sub {alpha}} {much_gt} 1. The maximum growth rate is obtained at {kappa}{sub {theta}}{rho}{sub {alpha}} on the order of unity and is nearly constant for the range of 0.7 < {upsilon}{sub {alpha}}/{upsilon}{sub A} < 2.5. On the other hand, the trapped particle response is dominated by the precessional drift resonance. The bounce resonant contribution is negligible. The growth rate peaks sharply at the value of {kappa}{sub {theta}}{rho}{sub {alpha}} such that the precessional drift resonance occurs for the most energetic trapped particles. The maximum growth rate due to the energetic trapped particles is comparable to that of circulating particles.

  6. Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

    SciTech Connect

    Fu, G.Y.; Cheng, C.Z.

    1992-07-01

    The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using the ideal MHD solution as the lowest order eigenfunction. The finite Larmor radius (FLR) effects and the finite drift orbit width (FDW) effects are included for both circulating and trapped energetic particles. It is shown that, for circulating particles, FLR and FDW effects have two opposite influences on the stability of the high-n TAE modes. First, they have the usual stabilizing effects by reducing the wave particle interaction strength. Second, they also have destabilizing effects by allowing more particles to resonate with the TAE modes. It is found that the growth rate induced by the circulating alpha particles increase linearly with toroidal mode number n for small {kappa}{sub {theta}}{rho}{sub {alpha}}, and decreases as 1/n for {kappa}{sub {theta}}{rho}{sub {alpha}} {much gt} 1. The maximum growth rate is obtained at {kappa}{sub {theta}}{rho}{sub {alpha}} on the order of unity and is nearly constant for the range of 0.7 < {upsilon}{sub {alpha}}/{upsilon}{sub A} < 2.5. On the other hand, the trapped particle response is dominated by the precessional drift resonance. The bounce resonant contribution is negligible. The growth rate peaks sharply at the value of {kappa}{sub {theta}}{rho}{sub {alpha}} such that the precessional drift resonance occurs for the most energetic trapped particles. The maximum growth rate due to the energetic trapped particles is comparable to that of circulating particles.

  7. Effect of Coherent Structures on Energetic Particle Intensity in the Solar Wind at 1 AU

    NASA Astrophysics Data System (ADS)

    Tessein, Jeffrey A.; Ruffolo, David; Matthaeus, William H.; Wan, Minping; Giacalone, Joe; Neugebauer, Marcia

    2015-10-01

    We present results from an analysis of Advanced Composition Explorer (ACE) observations of energetic particles in the 0.047–4.78 MeV range associated with shocks and discontinuities in the solar wind. Previous work found a strong correlation between coherent structures and energetic particles measured by ACE/EPAM. Coherent structures are identified using the Partial Variance of Increments (PVI) method, which is essentially a normalized vector increment. The correlation was based on a superposed epoch analysis using over 12 years of data. Here, we examine many individual high-PVI events to better understand this association emphasizing intervals selected from data with shock neighborhoods removed. We find that in many cases the local maximum in PVI is in a region of rising or falling energetic particle intensity, which suggests that magnetic discontinuities may act as barriers inhibiting the motion of energetic particles across them.

  8. Effect of Coherent Structures on Energetic Particle Intensity in the Solar Wind at 1 AU

    NASA Astrophysics Data System (ADS)

    Tessein, J.; Ruffolo, D. J.; Matthaeus, W. H.; Wan, M.; Giacalone, J.; Neugebauer, M.

    2015-12-01

    We present results from an analysis of ACE observations of energetic particles in the 0.047-4.78MeV range associated with shocks and discontinuities in the solar wind. Previous work (Tesseinet al. 2013) found a strong correlation between discontinuities, identified using a normalized vectorincrement and the intensity of energetic particles measured by ACE/EPAM, based on a superposedepoch analysis using over 12 years of data. Here, we examine many individual high-PVI eventsto better understand this association emphasizing intervals selected from data with shockneighborhoods removed. We find that in many cases the local maximum in PVI is in a region ofrising or falling energetic particle intensity, which suggests that magnetic discontinuities may act asbarriers inhibiting the motion of energetic particles across them.

  9. Effect of Coherent Structures on Energetic Particle Intensity in the Solar Wind at 1 AU

    NASA Astrophysics Data System (ADS)

    Tessein, Jeffrey A.; Ruffolo, David; Matthaeus, William H.; Wan, Minping; Giacalone, Joe; Neugebauer, Marcia

    2015-10-01

    We present results from an analysis of Advanced Composition Explorer (ACE) observations of energetic particles in the 0.047-4.78 MeV range associated with shocks and discontinuities in the solar wind. Previous work found a strong correlation between coherent structures and energetic particles measured by ACE/EPAM. Coherent structures are identified using the Partial Variance of Increments (PVI) method, which is essentially a normalized vector increment. The correlation was based on a superposed epoch analysis using over 12 years of data. Here, we examine many individual high-PVI events to better understand this association emphasizing intervals selected from data with shock neighborhoods removed. We find that in many cases the local maximum in PVI is in a region of rising or falling energetic particle intensity, which suggests that magnetic discontinuities may act as barriers inhibiting the motion of energetic particles across them.

  10. Effect of Energetic-Ion-Driven MHD Instabilities on Energetic-Ion-Transport in Compact Helical System and Large Helical Device

    SciTech Connect

    Isobe, M.; Ogawa, K.; Toi, K.; Osakabe, M.; Nagaoka, K.; Shimizu, A.; Spong, Donald A; Okumura, S.

    2010-01-01

    This paper describes 1) representative results on excitation of energetic-particle mode (EPM) and toroidicity-induced Alfven eigenmode (TAE) and consequent beam-ion losses in CHS, and 2) recent results on beam-ion transport and/or losses while EPMs are destabilized in LHD. Bursting EPMs and TAEs are often excited by co-injected beam ions in the high-beam ion pressure environment and give a significant effect on co-going beam ions in both experiments. It seems that in CHS, resonant beam ions are lost within a relatively short-time scale once they are anomalously transported due to energetic-ion driven MHD modes, whereas unlike CHS, redistribution of beam ions due to energetic-ion driven MHD modes is seen in LHD, suggesting that not all anomalously transported beam ions escape from the plasma.

  11. Study of wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation

    NASA Astrophysics Data System (ADS)

    Fu, S.

    2015-12-01

    There are many energetic electrons in the radiation belt of Earth. When the geomagnetic activity becomes stronger, the energy flux of energetic electrons will increase to more than ten times in the outer radiation belt, therefore it is very important to study how the energetic electrons generate and the lifetime of energetic electrons for space weather research. The acceleration of electrons in radiation belt is mainly depending on wave-particle interaction: the whistler mode chorus is the main driver for local acceleration mechanism, which could accelerate and loss energetic electrons; the geomagnetic pulsation ULF wave will cause energetic electron inward radial diffusion which will charge the electrons; recently observation results show us that the fast magnetosonic waves may also accelerate energetic electrons. For the reason that we try to study the wave-particle interaction between fast Magnetosonic and energetic electrons based on numerical simulation, in which the most important past is at the storm time the combination of highly warped Earth magnetic field and fast magnetosonic wave field will be applied for the electromagnetic environment of moving test particles. The energy, pitch angle and cross diffusion coefficients will be calculated respectively in this simulation to study how the electrons receive energy from fast magnetosonic wave. The diffusion coefficients within different dipole Earth magnetic field and non-dipole storm magnetic field are compared, while dynamics of electrons at selected initial energys are shown in our study.

  12. Evaluation of energetic particle effects on BUV data and atmospheric ozone

    NASA Technical Reports Server (NTRS)

    Herman, J. R.

    1977-01-01

    To aid investigations of energetic particle effects on the backscattered ultraviolet (BUV) instrumentation aboard Nimbus 4, solar proton events characterized as polar cap absorption events occurring in the period April 1970 to April 1976 were summarized. Energetic particle effects on total ozone above the 4 mb pressure level measured by Nimbus 4 were analyzed. Proceedings of a workshop meeting of operation aurorozone are included as background material for possible effects of bremsstrahlung on atmospheric ozone.

  13. Improving convergence in smoothed particle hydrodynamics simulations without pairing instability

    NASA Astrophysics Data System (ADS)

    Dehnen, Walter; Aly, Hossam

    2012-09-01

    The numerical convergence of smoothed particle hydrodynamics (SPH) can be severely restricted by random force errors induced by particle disorder, especially in shear flows, which are ubiquitous in astrophysics. The increase in the number NH of neighbours when switching to more extended smoothing kernels at fixed resolution (using an appropriate definition for the SPH resolution scale) is insufficient to combat these errors. Consequently, trading resolution for better convergence is necessary, but for traditional smoothing kernels this option is limited by the pairing (or clumping) instability. Therefore, we investigate the suitability of the Wendland functions as smoothing kernels and compare them with the traditional B-splines. Linear stability analysis in three dimensions and test simulations demonstrate that the Wendland kernels avoid the pairing instability for all NH, despite having vanishing derivative at the origin (disproving traditional ideas about the origin of this instability; instead, we uncover a relation with the kernel Fourier transform and give an explanation in terms of the SPH density estimator). The Wendland kernels are computationally more convenient than the higher order B-splines, allowing large NH and hence better numerical convergence (note that computational costs rise sublinear with NH). Our analysis also shows that at low NH the quartic spline kernel with NH ≈ 60 obtains much better convergence than the standard cubic spline.

  14. Flow instability in particle-bed nuclear reactors

    NASA Technical Reports Server (NTRS)

    Kerrebrock, J. L.; Kalamas, J.

    1993-01-01

    A three-dimensional model of the stability of the particle-bed reactor is presented, in which the fluid has mobility in three dimensions. The model accurately represents the stability at low Re numbers as well as the effects of the cold and hot frits and of the heat conduction and radiation in the particle bed. The model can be easily extended to apply to the cylindrical geometry of particle-bed reactors. Exemplary calculations are carried out, showing that a particle bed without a cold frit would be subject to instability if operated at the high-temperature ratios used for nuclear rockets and at power densities below about 4 MW/l; since the desired power density for such a reactor is about 40 MW/l, the operation at design exit temperature but at reduced power could be hazardous. Calculations show however that it might be possible to remove the instability problem by appropriate combinations of cold and hot frits.

  15. Particles Generation and Bose Instability in Primordial Rotating Black Holes

    NASA Astrophysics Data System (ADS)

    Gaina, Alex

    Black Hole's angular momentum (Instability) will be a Bose Instablity of Black Holes. It is mentioned that the Black Holes rotation does not change drastically the Levels real part of the Energy, but only the imaginary part of the Energy. The problem of motion of quantum particles in the gravitational field of a Black Hole presents a didactical interest, at least. It is showing at the same time the evolution of concepts in Science, since Kepler to Ours days.

  16. TRANSMISSION AND EMISSION OF SOLAR ENERGETIC PARTICLES IN SEMI-TRANSPARENT SHOCKS

    SciTech Connect

    Kocharov, Leon; Usoskin, Ilya; Laitinen, Timo; Vainio, Rami

    2014-06-01

    While major solar energetic particle (SEP) events are associated with coronal mass ejection (CME)-driven shocks in solar wind, accurate SEP measurements reveal that more than one component of energetic ions exist in the beginning of the events. Solar electromagnetic emissions, including nuclear gamma-rays, suggest that high-energy ions could also be accelerated by coronal shocks, and some of those particles could contribute to SEPs in interplanetary space. However, the CME-driven shock in solar wind is thought to shield any particle source beneath the shock because of the strong scattering required for the diffusive shock acceleration. In this Letter, we consider a shock model that allows energetic particles from the possible behind-shock source to appear in front of the shock simultaneously with SEPs accelerated by the shock itself. We model the energetic particle transport in directions parallel and perpendicular to the magnetic field in a spherical shock expanding through the highly turbulent magnetic sector with an embedded quiet magnetic tube, which makes the shock semi-transparent for energetic particles. The model energy spectra and time profiles of energetic ions escaping far upstream of the shock are similar to the profiles observed during the first hour of some gradual SEP events.

  17. Oblique electron fire hose instability: Particle-in-cell simulations

    NASA Astrophysics Data System (ADS)

    Hellinger, Petr; Trávníček, Pavel M.; Decyk, Victor K.; Schriver, David

    2014-01-01

    Nonlinear properties of the oblique resonant electron fire hose instability are investigated using two-dimensional particle-in-cell simulations in the Darwin approximation for weak initial growth rates. The weak electron fire hose instability has a self-destructive nonlinear behavior; it destabilizes a nonpropagating branch which only exists for a sufficiently strong temperature anisotropy. The nonlinear evolution leads to generation of nonpropagating waves which in turn scatter electrons and reduce their temperature anisotropy. As the temperature anisotropy is being reduced, the nonpropagating branch disappears and the generated standing waves are transformed to propagating whistler waves which are rapidly damped. Consequently, the oblique electron fire hose efficiently reduces the electron temperature anisotropy.

  18. Hybrid simulation of energetic particle effects on tearing modes in tokamak plasmas

    SciTech Connect

    Cai Huishan; Fu Guoyong

    2012-07-15

    The effects of energetic ions on stability of tearing mode are investigated by global kinetic/MHD hybrid simulations in a low beta tokamak plasma. The kinetic effects of counter circulating energetic ions from the non-adiabatic response are found to be strongly destabilizing while the effects from the adiabatic response are stabilizing. The net effect with both adiabatic and non-adiabatic contributions is destabilizing. On the other hand, the kinetic effects of co-circulating energetic ions from the non-adiabatic response are calculated to be weakly stabilizing while the corresponding adiabatic contribution is destabilizing for small energetic ion beta. The net effect is weakly stabilizing. The dependence of kinetic effects on energetic ion beta, gyroradius, and speed is studied systematically and the results agree in large part with the previous analytic results for the kinetic effects of circulating particles. For trapped energetic ions, their effects on tearing mode stability are dominated by the adiabatic response due to large banana orbit width and strong poloidal variation of particle pressure. The net effect of trapped energetic particles on tearing modes is much more destabilizing as compared to that of counter circulating particles at the same beta value.

  19. 12th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems

    SciTech Connect

    Berk, Herbert L.; Breizman, Boris N.

    2014-02-21

    The 12th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems took place in Austin, Texas (7–11 September 2011). This meeting was organized jointly with the 5th IAEA Technical Meeting on Theory of Plasma Instabilities (5–7 September 2011). The two meetings shared one day (7 September 2011) with presentations relevant to both groups. Some of the work reported at these meetings was then published in a special issue of Nuclear Fusion [Nucl. Fusion 52 (2012)]. Summaries of the Energetic Particle Conference presentations were given by Kazuo Toi and Boris Breizman. They respectively discussed the experimental and theoretical progress presented at the meeting. Highlights of this meeting include the tremendous progress that has been achieved in the development of diagnostics that enables the ‘viewing’ of internal fluctuations and allows comparison with theoretical predictions, as demonstrated, for example, in the talks of P. Lauber and M. Osakabe. The need and development of hardened diagnostics in the severe radiation environment, such as those that will exist in ITER, was discussed in the talks of V. Kiptily and V.A. Kazakhov. In theoretical studies, much of the effort is focused on nonlinear phenomena. For example, detailed comparison of theory and experiment on D-III-D on the n = 0 geodesic mode was reported in separate papers by R. Nazikian and G. Fu. A large number of theoretical papers were presented on wave chirping including a paper by B.N. Breizman, which notes that wave chirping from a single frequency may emanate continuously once marginal stability conditions have been established. Another area of wide interest was the detailed study of alpha orbits in a burning plasma, where losses can come from symmetry breaking due to finite coil number or magnetic field imperfections introduced by diagnostic or test modules. An important area of development, covered by M.A. Hole and D.A. Spong, is concerned with the self

  20. Theory of energetic/alpha particle effects on magnetohydrodynamic modes in tokamaks

    SciTech Connect

    Chen, L.; White, R.B.; Rewoldt, G.; Colestock, P.; Rutherford, P.H.; Chen, Y.P.; Ke, F.J.; Tsai, S.T.; Bussac, M.N.

    1989-01-01

    The presence of energetic particles is shown to qualitatively modify the stability properties of ideal as well as resistive magnetohydrodynamic (MHD) modes in tokamaks. Specifically, we demonstrate that, consistent with highpower ICRF heating experiments in JET, high energy trapped particles can effectively stabilize the sawtooth mode, providing a possible route to stable high current tokamak operation. An alternative stabilization scheme employing barely circulating energetic particles is also proposed. Finally, we present analytical and numerical studies on the excitations of high-n MHD modes via transit resonances with circulating alpha particles. 14 refs., 3 figs.

  1. Early Energetic Particle Irradiation of the HED Parent Body Regolith

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Garrison, D. H.; Rao, M. N.

    1996-01-01

    Previous studies have shown that many individual grains within the dark phase of the Kapoeta howardite were irradiated with energetic particles while residing on the surface of the early HED regolith. Particle tracks in these grains vary in density by more than an order of magnitude and undoubtedly were formed by energetic heavy (Fe) ions associated with early solar flares. Early Irradiation of HED Regolith: Concentrations of excess Ne alone are not sufficient to decide between competing galactic and solar irradiation models. However, from recent studies of depth samples of oriented lunar rocks, we have shown that the cosmogenic 21-Ne/22-Ne ratio produced in feldspar differs substantially between Galactic Cosmic Radiation (GCR) and solar protons, and that this difference is exactly that predicted from cross-section data. Using Ne literature data and new isotopic data we obtained on acid-etched, separated feldspar from both the light and dark phases of Kapoeta, we derive 21-Ne/22-Ne = 0.80 for the recent GCR irradiation and 21-Ne/22-Ne = 0.68 for the early regolith irradiation. This derived ratio indicates that the early Ne production in the regolith occurred by both galactic and solar protons. If we adopt a likely one-component regolith model in which all grains were exposed to galactic protons but individual grains had variable exposure to solar protons, we estimate that this early GCR irradiation lasted for about 3-6 m.y. More complex two-component regolith models involving separate solar and galactic irradiation would permit this GCR age to be longer. Higher-energy solar protons would permit the GCR to be longer. Higher-energy solar protons would permit the GCR age to be shorter. Further, cosmogenic 126(Xe) in Kapoeta dark is no more than a factor of about 2 higher than that observed in Kapoeta light. Because 126(Xe) can only be formed by galactic protons and not solar protons, these data support a short GCR irradiation for the HED regolith. This would also be

  2. Particle Energization via Tearing Instability with Global Self-Organization Constraints

    SciTech Connect

    Sarff, John; Guo, Fan

    2015-07-21

    The presentation reviews how tearing magnetic reconnection leads to powerful ion energization in reversed field pinch (RFP) plasmas. A mature MHD model for tearing instability has been developed that captures key nonlinear dynamics from the global to intermediate spatial scales. A turbulent cascade is also present that extends to at least the ion gyroradius scale, within which important particle energization mechanisms are anticipated. In summary, Ion heating and acceleration associated with magnetic reconnection from tearing instability is a powerful process in the RFP laboratory plasma (gyro-resonant and stochastic processes are likely candidates to support the observed rapid heating and other features, reconnection-driven electron heating appears weaker or even absent, energetic tail formation for ions and electrons). Global self-organization strongly impacts particle energization (tearing interactions that span to core to edge, global magnetic flux change produces a larger electric field and runaway, correlations in electric and magnetic field fluctuations needed for dynamo feedback, impact of transport processes (which can be quite different for ions and electrons), inhomogeneity on the system scale, e.g., strong edge gradients).

  3. Fluid electrons with kinetic closure for long wavelength energetic particles driven modes

    SciTech Connect

    Chen Yang; Parker, Scott E.

    2011-05-15

    A kinetic electron closure scheme is presented for the fluid electron model that has been implemented in the GEM code [J. Lang, Y. Chen, S. E. Parker, and G.-Y. Fu, Phys. Plasmas 16, 102101 (2009)]. The most important element of the closure scheme is a complete Ohm's law for the parallel electric field E{sub ||}, derived by combining the quasineutrality condition, the Ampere's equation and the v{sub ||} moment of the gyrokinetic equations. A discretization method for the closure scheme is presented and studied in detail for a three-dimensional shearless slab plasma. It is found that for long wavelength shear Alfven waves the kinetic closure scheme is both more accurate and more robust than the previous GEM algorithm [Y. Chen and S. E. Parker, J. Comput. Phys. 189, 463 (2003)], whereas for the ion-gradient-driven instability the previous algorithm is more efficient. The fluid electron model with kinetic electron closure is useful for studying energetic particles driven modes with electron kinetic damping effects.

  4. Flow instability in particle-bed nuclear reactors

    NASA Technical Reports Server (NTRS)

    Kerrebrock, Jack L.

    1993-01-01

    The particle-bed core offers mitigation of some of the problems of solid-core nuclear rocket reactors. Dividing the fuel elements into small spherical particles contained in a cylindrical bed through which the propellant flows radially, may reduce the thermal stress in the fuel elements, allowing higher propellant temperatures to be reached. The high temperature regions of the reactor are confined to the interior of cylindrical fuel assemblies, so most of the reactor can be relatively cool. This enables the use of structural and moderating materials which reduce the minimum critical size and mass of the reactor. One of the unresolved questions about this concept is whether the flow through the particle-bed will be well behaved, or will be subject to destructive flow instabilities. Most of the recent analyses of the stability of the particle-bed reactor have been extensions of the approach of Bussard and Delauer, where the bed is essentially treated as an array of parallel passages, so that the mass flow is continuous from inlet to outlet through any one passage. A more general three dimensional model of the bed is adopted, in which the fluid has mobility in three dimensions. Comparison of results of the earlier approach to the present one shows that the former does not accurately represent the stability at low Re. The more complete model presented should be capable of meeting this deficiency while accurately representing the effects of the cold and hot frits, and of heat conduction and radiation in the particle-bed. It can be extended to apply to the cylindrical geometry of particle-bed reactors without difficulty. From the exemplary calculations which were carried out, it can be concluded that a particle-bed without a cold frit would be subject to instability if operated at the high temperatures desired for nuclear rockets, and at power densities below about 4 megawatts per liter. Since the desired power density is about 40 megawatts per liter, it can be concluded

  5. A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

    NASA Astrophysics Data System (ADS)

    Verkhoglyadova, Olga P.; Zank, Gary P.; Li, Gang

    2015-02-01

    Understanding the physics of Solar Energetic Particle (SEP) events is of importance to the general question of particle energization throughout the cosmos as well as playing a role in the technologically critical impact of space weather on society. The largest, and often most damaging, events are the so-called gradual SEP events, generally associated with shock waves driven by coronal mass ejections (CMEs). We review the current state of knowledge about particle acceleration at evolving interplanetary shocks with application to SEP events that occur in the inner heliosphere. Starting with a brief outline of recent theoretical progress in the field, we focus on current observational evidence that challenges conventional models of SEP events, including complex particle energy spectra, the blurring of the distinction between gradual and impulsive events, and the difference inherent in particle acceleration at quasi-parallel and quasi-perpendicular shocks. We also review the important problem of the seed particle population and its injection into particle acceleration at a shock. We begin by discussing the properties and characteristics of non-relativistic interplanetary shocks, from their formation close to the Sun to subsequent evolution through the inner heliosphere. The association of gradual SEP events with shocks is discussed. Several approaches to the energization of particles have been proposed, including shock drift acceleration, diffusive shock acceleration (DSA), acceleration by large-scale compression regions, acceleration by random velocity fluctuations (sometimes known as the "pump mechanism"), and others. We review these various mechanisms briefly and focus on the DSA mechanism. Much of our emphasis will be on our current understanding of the parallel and perpendicular diffusion coefficients for energetic particles and models of plasma turbulence in the vicinity of the shock. Because of its importance both to the DSA mechanism itself and to the particle

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  7. Charged Particle Energization and Transport in Reservoirs throughout the Heliosphere: 1. Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Roelof, E. C.

    2015-09-01

    “Reservoirs” of energetic charged particles are regions where the particle population is quasi-trapped in large-scale (relative to the gyroradii) magnetic field structures. Reservoirs are found throughout the heliosphere: the huge heliosheath (90particles within these reservoirs is produced by the interaction when the particle magnetic drifts have a component along the large-scale electric fields produced by plasma convection. The appropriate description of this transport is “weak scattering”, in which the particle's first adiabatic invariant (magnetic moment) is approximately conserved while the particle itself moves rather freely along magnetic field lines. Considerable insight into the observed properties of energization processes can be gained from a remarkably simple equation that describes the particle's fractional time-rate-of-change of momentum (dlnp/dt) which depends only upon its pitch angle, the divergence of the plasma velocity (V⊥) transverse to the magnetic field), and the inner product of (V⊥) with the curvature vector of the field lines. The possibilities encompassed in this simple (but general) equation are quite rich, so we restrict our application of it in this paper to the compressive acceleration of SEPs within CMEs.

  8. 3-D Particle Simulation of Current Sheet Instabilities

    NASA Astrophysics Data System (ADS)

    Wang, Zhenyu; Lin, Yu; Wang, Xueyi; Tummel, Kurt; Chen, Liu

    2015-11-01

    The electrostatic (ES) and electromagnetic (EM) instabilities of a Harris current sheet are investigated using a 3-D linearized (δf) gyrokinetic (GK) electron and fully kinetic (FK) ion (GeFi) particle simulation code. The equilibrium magnetic field consists of an asymptotic anti-parallel Bx 0 and a guide field BG. The ES simulations show the excitation of lower-hybrid drift instability (LHDI) at the current sheet edge. The growth rate of the 3-D LHDI is scanned through the (kx ,ky) space. The most unstable modes are found to be at k∥ = 0 for smaller ky. As ky increases, the growth rate shows two peaks at k∥ ≠ 0 , consistent with analytical GK theory. The eigenmode structure and growth rate of LHDI obtained from the GeFi simulation agree well with those obtained from the FK PIC simulation. Decreasing BG, the asymptotic βe 0, or background density can destabilize the LHDI. In the EM simulation, tearing mode instability is dominant in the cases with ky kx , there exist two unstable modes: a kink-like (LHDI) mode at the current sheet edge and a sausage-like mode at the sheet center. The results are compared with the GK eigenmode theory and the FK simulation.

  9. Black holes as particle detectors: evolution of superradiant instabilities

    NASA Astrophysics Data System (ADS)

    Brito, Richard; Cardoso, Vitor; Pani, Paolo

    2015-07-01

    Superradiant instabilities of spinning black holes (BHs) can be used to impose strong constraints on ultralight bosons, thus turning BHs into effective particle detectors. However, very little is known about the development of the instability and whether its nonlinear time evolution accords to the linear intuition. For the first time, we attack this problem by studying the impact of gravitational-wave (GW) emission and gas accretion on the evolution of the instability. Our quasi-adiabatic, fully-relativistic analysis shows that: (i) GW emission does not have a significant effect on the evolution of the BH, (ii) accretion plays an important role, and (iii) although the mass of the scalar cloud developed through superradiance can be a sizeable fraction of the BH mass, its energy-density is very low and backreaction is negligible. Thus, massive BHs are well described by the Kerr geometry even if they develop bosonic clouds through superradiance. Using Monte Carlo methods and very conservative assumptions, we provide strong support to the validity of the linearized analysis and to the bounds of previous studies.

  10. Energetic particles detected by the Electron Reflectometer instrument on the Mars Global Surveyor, 1999-2006

    NASA Astrophysics Data System (ADS)

    Delory, Gregory T.; Luhmann, Janet G.; Brain, David; Lillis, Robert J.; Mitchell, David L.; Mewaldt, Richard A.; Falkenberg, Thea Vilstrup

    2012-06-01

    We report the observation of galactic cosmic rays and solar energetic particles by the Electron Reflectometer instrument aboard the Mars Global Surveyor (MGS) spacecraft from May of 1999 to the mission conclusion in November 2006. Originally designed to detect low-energy electrons, the Electron Reflectometer also measured particles with energies >30 MeV that penetrated the aluminum housing of the instrument and were detected directly by microchannel plates in the instrument interior. Using a combination of theoretical and experimental results, we show how the Electron Reflectometer microchannel plates recorded high energy galactic cosmic rays with ˜45% efficiency. Comparisons of this data to galactic cosmic ray proton fluxes obtained from the Advanced Composition Explorer yield agreement to within 10% and reveal the expected solar cycle modulation as well as shorter timescale variations. Solar energetic particles were detected by the same mechanism as galactic cosmic rays; however, their flux levels are far more uncertain due to shielding effects and the energy-dependent response of the microchannel plates. Using the solar energetic particle data, we have developed a catalog of energetic particle events at Mars associated with solar flares and coronal mass ejections, which includes the identification of interplanetary shocks. MGS observations of energetic particles at varying geometries between the Earth and Mars that include shocks produced by halo, limb, and backsided events provide a unique data set for use by the heliophysics modeling community.

  11. Trapped Particle Instability in Kinetic Stabilized Tandem Mirror

    NASA Astrophysics Data System (ADS)

    Berk, Herbert; Pratt, Jane

    2009-11-01

    The kinetic stabilizer tandem mirror (KSTM) devised by R. F. Post (J. Fus. Energy 2007) is an innovative concept devised to stabilize a symmetric tandem mirror machines using a concept devised by D. Ryutov (Proc. of Course and Workshop, Varenna, Italy, 1987) and empirically verified in the Gas Dynamic Trap (Ivanov, et. al. Trans. Fusion Technology 39, 127, 2001). The KSTM uses the momentum flux of unconfined particles that only sample the outer end regions of the mirror where there is very favorable field line curvature. Charged ion beams at relatively low energy are externally injected into the ends and reflected out from the ends. MHD stability with a power drain less than the fusion power production can be achieved. We examine the effect of fast growing trapped particle instability (Berk et. al. Sov J. Plasma Phys. 1983) on the overall stability. In this case stability is very sensitive to the electron connection between the stabilizer and end plug.

  12. A cosmic ray driven instability

    NASA Technical Reports Server (NTRS)

    Dorfi, E. A.; Drury, L. O.

    1985-01-01

    The interaction between energetic charged particles and thermal plasma which forms the basis of diffusive shock acceleration leads also to interesting dynamical phenomena. For a compressional mode propagating in a system with homogeneous energetic particle pressure it is well known that friction with the energetic particles leads to damping. The linear theory of this effect has been analyzed in detail by Ptuskin. Not so obvious is that a non-uniform energetic particle pressure can addition amplify compressional disturbances. If the pressure gradient is sufficiently steep this growth can dominate the frictional damping and lead to an instability. It is important to not that this effect results from the collective nature of the interaction between the energetic particles and the gas and is not connected with the Parker instability, nor with the resonant amplification of Alfven waves.

  13. Elemental composition of solar energetic particles in 1977 and 1978

    NASA Technical Reports Server (NTRS)

    Cook, W. R.; Stone, E. C.; Vogt, R. E.; Trainor, J. H.; Webber, W. R.

    1980-01-01

    Measurements of the elemental composition of energetic nuclei with atomic numbers between 2 and 28 from seven major solar flares from September 1977 to May 1978 are presented. The abundance observations were made with the Low Energy Telescope systems of the cosmic ray detector systems on board the Voyager 1 and 2 spacecraft between 1 and 3 AU. Examination of the abundance ratios of the flare nuclei relative to oxygen reveals significant variations from event to event and between energetic nuclei and photospheric abundances, with an average composition, except for C and N, very similar to that of the galactic cosmic ray source. For the four flare events for which the elemental abundances exhibit no significant energy dependence in the energy range observed, it is found that the enhancement of energetic nuclei relative to their photospheric abundance are similar and not monotonic with atomic number, with the metallic nuclei showing an enhancement factor of approximately 5 and the volatiles showing one closer to 1.

  14. Solar energetic particles events observed by Prognoz-10 Intercosmos (May-October 1985)

    NASA Technical Reports Server (NTRS)

    Lutserko, V.; Fischer, S.; Vandas, M.; Kudela, K.; Stivka, M.

    1987-01-01

    On 26 April 1985, Intershock began observation of a solar energetic particle (SEP) event, resulting from a 3B solar flare which originated on 24 April. The following observation period was quiet with only a few weak increases of low-energy protons of several days duration. Two prominent SEP events occurred on 9 July 1985 (start 0133 UT, position S13, W25) and 17 July (no optical data, type II radio burst from 0333 to 0348 UT). These mass ejection and particle propagation episodes were studied on the basis of X-ray, radio, and energetic particle emissions.

  15. Solar energetic particles events observed by Prognoz-10 Intercosmos (May-October 1985)

    NASA Astrophysics Data System (ADS)

    Lutserko, V.; Fischer, S.; Vandas, M.; Kudela, K.; Stivka, M.

    1987-09-01

    On 26 April 1985, Intershock began observation of a solar energetic particle (SEP) event, resulting from a 3B solar flare which originated on 24 April. The following observation period was quiet with only a few weak increases of low-energy protons of several days duration. Two prominent SEP events occurred on 9 July 1985 (start 0133 UT, position S13, W25) and 17 July (no optical data, type II radio burst from 0333 to 0348 UT). These mass ejection and particle propagation episodes were studied on the basis of X-ray, radio, and energetic particle emissions.

  16. Nonlinear dynamics of toroidal Alfvén eigenmodes driven by energetic particles

    SciTech Connect

    Zhu, J.; Ma, Z. W.; Fu, G. Y.

    2013-07-15

    A kinetic simulation code based on a reduced model is developed to study dynamic evolutions of a single toroidicity-induced shear Alfvén eigenmode driven by energetic particles. For zero background damping, it is found that the wave amplitude in nonlinear phase can either saturate for weak energetic particle drives or slowly increase for strong drives. This slow nonlinear growth in strong drive cases is found to be associated with broadening and overlapping of resonances between the wave and trapped particles. For the near-marginal-stability case with a large background damping, the mode nonlinear evolution exhibits strong upward and downward frequency chirping in multiple branches. A hole/clump formation is observed clearly in the corresponding evolution of energetic particle distribution.

  17. Ionization of the Earth's Upper Atmosphere in Large Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Wolff, E.; Burrows, J.; Kallenrode, M.; von Koenig, M.; Kuenzi, K. F.; Quack, M.

    2001-12-01

    Energetic charged particles ionize the upper terrestrial atmosphere. Sofar, chemical consequences of precipitating particles have been discussed for solar protons with energies up to a few hundred MeV. We present a refined model for the interaction of energetic particles with the atmosphere based on a Monte-Carlo simulation. The model includes higher energies and other particle species, such as energetic solar electrons. Results are presented for well-known solar events, such as July 14, 2000, and are extrapolated to extremely large events, such as Carrington's white light flare in 1859, which from ice cores has been identified ass the largest impulsive NO3 event in the interval 1561 -- 1994 (McCracken et al., 2001).

  18. ENERGETIC PARTICLE OBSERVATIONS AND PROPAGATION IN THE THREE-DIMENSIONAL HELIOSPHERE DURING THE 2006 DECEMBER EVENTS

    SciTech Connect

    Malandraki, O. E.; Marsden, R. G.; Tranquille, C.; Lario, D.; Heber, B.; Mewaldt, R. A.; Cohen, C. M. S.; Lanzerotti, L. J.; Forsyth, R. J.; Elliott, H. A.; Vogiatzis, I. I.; Geranios, A.

    2009-10-10

    We report observations of solar energetic particles obtained by the HI-SCALE and COSPIN/LET instruments onboard Ulysses during the period of isolated but intense solar activity in 2006 December, in the declining phase of the solar activity cycle. We present measurements of particle intensities and also discuss observations of particle anisotropies and composition in selected energy ranges. Active Region 10930 produced a series of major solar flares with the strongest one (X9.0) recorded on December 5 after it rotated into view on the solar east limb. Located over the South Pole of the Sun, at >72{sup 0}S heliographic latitude and 2.8 AU radial distance, Ulysses provided unique measurements for assessing the nature of particle propagation to high latitudes under near-minimum solar activity conditions, in a relatively undisturbed heliosphere. The observations seem to exclude the possibility that magnetic field lines originating at low latitudes reached Ulysses, suggesting either that the energetic particles observed as large solar energetic particle (SEP) events over the South Pole of the Sun in 2006 December were released when propagating coronal waves reached high-latitude field lines connected to Ulysses, or underwent perpendicular diffusion. We also discuss comparisons with energetic particle data acquired by the STEREO and Advanced Composition Explorer in the ecliptic plane near 1 AU during this period.

  19. Solar abundances from gamma-ray spectroscopy - Comparisons with energetic particle, photospheric, and coronal abundances

    NASA Technical Reports Server (NTRS)

    Murphy, R. J.; Ramaty, R.; Reames, D. V.; Kozlovsky, B.

    1991-01-01

    Accelerated particle and ambient gas abundances have been derived using solar flare gamma-ray spectroscopy. The results with photospheric and coronal abundances, as well as with solar energetic particle abundances. This is the first time that the composition of accelerated particles interacting in an astrophysical source has been compared with the composition of particles escaping from the source. The analysis shows that the derived composition of the accelerated particles is different from the composition of particles observed in large proton flares; rather, it resembles the composition observed in He-3-rich flares. The analysis also suggests an ambient gas composition which differs from the composition of both the photosphere and the corona.

  20. Effect of coherent structures on energetic particle intensity in the solar wind

    NASA Astrophysics Data System (ADS)

    Tessein, Jeffrey A.

    Solar energetic particles in the solar wind are accelerated in both solar flares and shocks assocated with fast coronal mass ejections. They follow the interplanetary magnetic field and, upon reaching Earth, have implications for space weather. Space weather affects astronaut health and orbiting equipment through radiation hazard and electrical infrastructure on the ground with ground induced currents. Economic im- pacts include disruption of GPS and redirection of commercial polar flights due to a dangerous radiation environment over the poles. By studying how these particles interact with the magnetic fields we can better predict onset times and diffusion of these events. We find, using superposed epoch analysis and conditional statisitics from spacecraft observations that there is a strong association between energetic particles in the solar wind and magnetic discontinuities. This may be related to turbulent dissipa- tion mechanisms in which coherent structures in the solar wind seem to be preferred sites of heating, plasma instabilites and dissipation. In the case of energetic particles, magnetic reconnection and transport in flux tubes are likely to play a role. Though we focus on data away from large shocks, trapping can occur in the downstream region of shocks due to the preponderance of compressive turbulence in these areas. This thesis lays the ground work for the results described above with an intro- duction to solar wind and heliospheric physics in Chapter 1. Chapter 2 is an intro- duction to the acceleration mechanisms that give rise to observed energetic particle events. Chapter 3 describes various data analysis techniques and statistics that are bread and butter when analyzing spacecraft data for turbulence and energetic particle studies. Chapter 4 is a digression that covers preliminary studies that were done on the side; scale dependent kurtosis, ergodic studies and initial conditions for simulations. Chapter 5 contains that central published

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

    NASA Technical Reports Server (NTRS)

    Tkalcevic, S.

    1982-01-01

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

  2. SIZE DISTRIBUTIONS OF SOLAR FLARES AND SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-09-10

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast ({>=}1000 km s{sup -1}) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes ({alpha} values) of power-law size distributions of the peak 1-8 A fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes {>=}1 pr cm{sup -2} s{sup -1} sr{sup -1}) and (b) fast CMEs were {approx}1.3-1.4 compared to {approx}1.2 for the peak proton fluxes of >10 MeV SEP events and {approx}2 for the peak 1-8 A fluxes of all SXR flares. The difference of {approx}0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  3. Size Distributions of Solar Flares and Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-01-01

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (much > 1000 km/s) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (alpha values) of power-law size distributions of the peak 1-8 Angs fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes much > 1 pr/sq cm/s/sr) and (b) fast CMEs were approx 1.3-1.4 compared to approx 1.2 for the peak proton fluxes of >10 MeV SEP events and approx 2 for the peak 1-8 Angs fluxes of all SXR flares. The difference of approx 0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  4. Energetic particles in the pre-dawn magnetotail of Jupiter

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    A detailed account is given of the energetic electron and proton populations as observed with Voyagers 1 and 2 during their passes through the dawn magnetotail of Jupiter. The region between 20 and 150 R sub J is dominated by a thin plasma sheet, where trapped energetic electron and proton fluxes reach their maximum. Proton spectra can be represented by an exponential in rigidity with a characteristic energy of approximately 50 keV. Proton anisotropies were consistent with corotation even at 100 R sub J. A major proton acceleration event as well as several cases of field aligned proton streaming were observed. The flux of 0.4 MeV protons decreases by three orders of magnitude between 30 and 90 R sub J and then remains relatively constant to the magnetopause. Fine structure in the data indicate longitudinal asymmetries with respect to the dipole orientation. Electron spectra in the magnetosheath and interplanetary space are modulated by the Jovian longitude relative to the subsolar point.

  5. On Nonlinear Self-interaction of Geodesic Acoustic Mode Driven by Energetic Particles

    SciTech Connect

    G. Y. Fu

    2010-06-04

    It is shown that nonlinear self-interaction of energetic particle-driven Geodesic Acoustic Mode does not generate a second harmonic in radial electric field using the fluid model. However, kinetic effects of energetic particles can induce a second harmonic in the radial electric field. A formula for the second order plasma density perturbation is derived. It is shown that a second harmonic of plasma density perturbation is generated by the convective nonlinearity of both thermal plasma and energetic particles. Near the midplane of a tokamak, the second order plasma density perturbation (the sum of second harmonic and zero frequency sideband) is negative on the low field side with its size comparable to the main harmonic at low uctuation level. These analytic predictions are consistent with the recent experimental observation in DIII-D.

  6. On Nonlinear Self-interaction of Geodesic Acoustic Mode Driven By Energetic Particles

    SciTech Connect

    G.Y. Fu

    2010-10-01

    It is shown that nonlinear self-interaction of energetic particle-driven Geodesic Acoustic Mode does not generate a second harmonic in radial electric field using the fluid model. However, kinetic effects of energetic particles can induce a second harmonic in the radial electric field. A formula for the second order plasma density perturbation is derived. It is shown that a second harmonic of plasma density perturbation is generated by the convective nonlinearity of both thermal plasma and energetic particles. Near the midplane of a tokamak, the second order plasma density perturbation (the sum of second harmonic and zero frequency sideband) is negative on the low field side with its size comparable to the main harmonic at low fluctuation level. These analytic predictions are consistent with the recent experimental observation in DIII-D.

  7. Ionization states of helium in He-3-rich solar energetic particle events

    NASA Technical Reports Server (NTRS)

    Klecker, B.; Hovestadt, D.; Moebius, E.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.

    1983-01-01

    Results of a systematic study of the ionic charge state of helium in the energy range 0.6-1.0 MeV/nucleon for He-3-rich solar energetic particle events during the time period August 1978 to October 1979 are reported. The data have been obtained with the Max-Planck-Institut/University of Maryland experiment on ISEE-3. Whereas for solar energetic particle events with no enrichment of He-3 relative to He-4 surprisingly large abundances of singly ionized helium have been reported recently, He-3-rich solar energetic particle events do not show significant abundances of He-3(+). This result is consistent with current theories explaining large compositional anomalies by mass per charge dependent selective heating of the minor ion species.

  8. MINIS Balloon and RHESSI Observations of a Solar Energetic Particle Event

    NASA Astrophysics Data System (ADS)

    McCarthy, M. P.; Smith, D. M.; Sample, J. G.; Bale, S.; Bering, E. A.; Blake, J. B.; Collier, A. B.; Holzworth, R. H.; Hughes, A. R.; Kokorowski, M.; Lay, E. H.; Lin, R. P.; Millan, R. M.; Moraal, H.; O'Brien, T. P.; Parks, G. K.; Pulupa, M.; Reddell, B. D.; Share, G. H.; Shih, A. Y.; Stoker, P.; Woodger, L. A.

    2005-12-01

    An X3.8 class solar flare on 17Jan05 was immediately followed by large increases in energetic proton and electron fluxes within Earth's magnetosphere. Nuclear reactions from the impact of solar energetic particles on atmospheric constituents result in the emission of characteristic gamma rays, which are informative about the incoming particle spectrum. The first MINIS balloon, launched from SANAE in Antarctica (L=4), carried an x-ray spectrometer (energy range 0.05--10.0~MeV), and reached ceiling (35~km) about 5~hours after the flare ended, when GOES energetic particle fluxes were peaking. During this event, the MINIS balloon payload at high latitude, and the RHESSI high resolution spectrometer at lower latitude obtained spectra of atmospheric gamma emissions. We present and compare these higher and lower latitude observations.

  9. Integrated Science Investigation of the Sun (ISIS): Design of the Energetic Particle Investigation

    NASA Technical Reports Server (NTRS)

    McComas, D. J.; Alexander, N.; Angold, N.; Bale, S.; Beebe, C.; Birdwell, B.; Boyle, M.; Burgum, J. M.; Burnham, J. A.; Christian, E. R.; Shuman, S.; von Rosenvinge, T. T.

    2014-01-01

    The Integrated Science Investigation of the Sun (ISIS) is a complete science investigation on the Solar Probe Plus (SPP) mission, which flies to within nine solar radii of the Sun's surface. ISIS comprises a two-instrument suite to measure energetic particles over a very broad energy range, as well as coordinated management, science operations, data processing, and scientific analysis. Together, ISIS observations allow us to explore the mechanisms of energetic particles dynamics, including their: (1) Origins-defining the seed populations and physical conditions necessary for energetic particle acceleration; (2) Acceleration-determining the roles of shocks, reconnection, waves, and turbulence in accelerating energetic particles; and (3) Transport-revealing how energetic particles propagate from the corona out into the heliosphere. The two ISIS Energetic Particle Instruments measure lower (EPI-Lo) and higher (EPI-Hi) energy particles. EPI-Lo measures ions and ion composition from approx. 20 keV/nucleon-15 MeV total energy and electrons from approx.25-1000 keV. EPI-Hi measures ions from approx. 1-200 MeV/nucleon and electrons from approx. 0.5-6 MeV. EPI-Lo comprises 80 tiny apertures with fields-of-view (FOVs) that sample over nearly a complete hemisphere, while EPI-Hi combines three telescopes that together provide five large-FOV apertures. ISIS observes continuously inside of 0.25 AU with a high data collection rate and burst data (EPI-Lo) coordinated with the rest of the SPP payload; outside of 0.25 AU, ISIS runs in low-rate science mode whenever feasible to capture as complete a record as possible of the solar energetic particle environment and provide calibration and continuity for measurements closer in to the Sun. The ISIS Science Operations Center plans and executes commanding, receives and analyzes all ISIS data, and coordinates science observations and analyses with the rest of the SPP science investigations. Together, ISIS' unique observations on SPP will

  10. Planned investigation of energetic particle populations (approximately 20-500 keV) in the close Martian environment

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Rusznyak, P.; Gringauz, K.; Klimenko, I.; Lutsenko, V.; Verigin, M.; Korth, A.; Richter, A.; Fischer, S.; Polasek, C.

    1995-04-01

    Energetic particle observations made by the Irish SLED instrument on the Phobos 2 spacecraft in 1989 have revealed the presence, within the overall energy range less than 30 keV - greater than 3.2 MeV, of variously located energetic particle populations in the close Marian environment. The signatures of characteristic boundaries have also been recorded for the first time in energetic particles in the distant Martian magnetotail. The new SLED-II instrument on the Mars-94 Mission is designed to study in detail, with 4 pi measurement capability, these and other energetic particle phenomena at Mars, while operating, over an extended period, at low altitudes above the planet.

  11. Energetic particle recurrence and escape during solar cycle 20

    NASA Astrophysics Data System (ADS)

    Gold, R. E.; Roelof, E. C.

    1980-10-01

    Low-energy solar particle data have been combined from a multi-spacecraft near-earth data set covering most of solar cycle 20 (1966-1976). Particle intensity profiles have been ordered in the natural heliographic coordinate system of the estimated high coronal connection longitude of the foot point of the interplanetary field line. The recurrence trends of approximately 1-MeV solar particles become more apparent in this coordinate system than when plotted versus time, and thereby extend the evidence for regions of continual injection and escape from the corona. Intercomparison of solar particles and solar wind streams in heliographic longitude suggests that the origin of stream-associated spatial particle events seen at 1 AU is solar rather than interplanetary.

  12. Filamentation Instability of Counterpropagating Charged Particle Beams: Statistical Properties

    SciTech Connect

    Dieckmann, M. E.

    2008-10-15

    The filamentation instability (FI) driven by beams of counter-propagating electrons is examined with one-dimensional (1D) and two-dimensional (2D) particle-in-cell (PIC) simulations. The 1D simulation reveals the saturation mechanism of the FI. The magnetic pressure gradient displaces the electrons. The resulting electrostatic field inhibits together with the magnetic field a further growth of the filaments by suppressing the electron motion. The FI evolves into a stationary equilibrium in 1D, which shows a statistical distribution of the filament sizes that resembles a Gumbel distribution. The 2D PIC simulation allows the filaments to move around each other and filaments carrying currents of equal polarity can merge. The time-evolution of the characteristic size of the filaments in the 2D simulation is measured. It increases linearly with the time.

  13. Energetic charged particle sources in Saturn's and Jupiter's magnetoshperes

    NASA Astrophysics Data System (ADS)

    Roussos, Elias

    2015-04-01

    In this talk we review observations of high energy particle sources in the jovian and saturnian magnetospheres. We focus on both direct sources (e.g. CRAND, direct CME particle entry) and acceleration mechanisms (e.g. adiabatic heating, centrifugal interchange injections, wave particle interactions, impulsive events/transient radiation belts, reconnection etc.), using data mostly from Cassini, Galileo and Ulysses. We use a comparative approach, theoretical context and references to Earth observations to understand which of the sources and acceleration processes are fundamental for fast-rotating magnetospheres with internal plasma sources and which ones can be attributed to the specifics of each system.

  14. Energetic particles of the outer regions of planetary magnetospheres

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  15. Pitch-angle scattering of energetic particles with adiabatic focusing

    SciTech Connect

    Tautz, R. C.; Shalchi, A.; Dosch, A. E-mail: andreasm4@yahoo.com

    2014-10-20

    Understanding turbulent transport of charged particles in magnetized plasmas often requires a model for the description of random variations in the particle's pitch angle. The Fokker-Planck coefficient of pitch-angle scattering, which is used to describe scattering parallel to the mean magnetic field, is therefore of central importance. Whereas quasi-linear theory assumes a homogeneous mean magnetic field, such a condition is often not fulfilled, especially for high-energy particles. Here, a new derivation of the quasi-linear approach is given that is based on the unperturbed orbit found for an adiabatically focused mean magnetic field. The results show that, depending on the ratio of the focusing length and the particle's Larmor radius, the Fokker-Planck coefficient is significantly modified but agrees with the classical expression in the limit of a homogeneous mean magnetic field.

  16. Special section containing papers presented at the 13th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems (Beijing, China, 17-20 September 2013) Special section containing papers presented at the 13th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems (Beijing, China, 17-20 September 2013)

    NASA Astrophysics Data System (ADS)

    Lin, Z.

    2014-10-01

    In magnetic fusion plasmas, a significant fraction of the kinetic pressure is contributed by superthermal charged particles produced by auxiliary heating (fast ions and electrons) and fusion reactions (a-particles). Since these energetic particles are often far away from thermal equilibrium due to their non-Maxwellian distribution and steep pressure gradients, the free energy can excite electromagnetic instabilities to intensity levels well above the thermal fluctuations. The resultant electromagnetic turbulence could induce large transport of energetic particles, which could reduce heating efficiency, degrade overall plasma confinement, and damage fusion devices. Therefore, understanding and predicting energetic particle confinement properties are critical to the success of burning plasma experiments such as ITER since the ignition relies on plasma self-heating by a-particles. To promote international exchanges and collaborations on energetic particle physics, the biannual conference series under the auspices of the International Atomic Energy Agency (IAEA) were help in Kyiv (1989), Aspenas (1991), Trieste (1993), Princeton (1995), JET/Abingdon (1997), Naka (1999), Gothenburg (2001), San Diego (2003), Takayama (2005), Kloster Seeon (2007), Kyiv (2009), and Austin (2011). The papers in this special section were presented at the most recent meeting, the 13th IAEA Technical Meeting on Energetic Particles in Magnetic Confinement Systems, which was hosted by the Fusion Simulation Center, Peking University, Beijing, China (17-20 September 2013). The program of the meeting consisted of 71 presentations, including 13 invited talks, 26 oral contributed talks, 30 posters, and 2 summary talks, which were selected by the International Advisory Committee (IAC). The IAC members include H. Berk, L.G. Eriksson, A. Fasoli, W. Heidbrink, Ya. Kolesnichenko, Ph. Lauber, Z. Lin, R. Nazikian, S. Pinches, S. Sharapov, K. Shinohara, K. Toi, G. Vlad, and X.T. Ding. The conference program

  17. THE POWER-LAW SPECTRA OF ENERGETIC PARTICLES DURING MULTI-ISLAND MAGNETIC RECONNECTION

    SciTech Connect

    Drake, J. F.; Swisdak, M.; Fermo, R. E-mail: swisdak@umd.edu

    2013-01-20

    Power-law distributions are a near-universal feature of energetic particle spectra in the heliosphere. Anomalous cosmic rays (ACRs), super-Alfvenic ions in the solar wind, and the hardest energetic electron spectra in flares all have energy fluxes with power laws that depend on energy E approximately as E {sup -1.5}. We present a new model of particle acceleration in systems with a bath of merging magnetic islands that self-consistently describes the development of velocity-space anisotropy parallel and perpendicular to the local magnetic field and includes the self-consistent feedback of pressure anisotropy on the merging dynamics. By including pitch-angle scattering we obtain an equation for the omnidirectional particle distribution f (v, t) that is solved in closed form to reveal v {sup -5} (corresponding to an energy flux varying as E {sup -1.5}) as a near-universal solution as long as the characteristic acceleration time is short compared with the characteristic loss time. In such a state, the total energy in the energetic particles reaches parity with the remaining magnetic free energy. More generally, the resulting transport equation can serve as the basis for calculating the distribution of energetic particles resulting from reconnection in large-scale inhomogeneous systems.

  18. The Energy Spectrum of Energetic Particles Downstream of Turbulent Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Giacalone, Joe; Neugebauer, Marcia

    2008-01-01

    Using simple analytic considerations, numerical simulations, and data analysis, we discuss the physics of charged-particle acceleration by turbulent, rippled, collisionless shocks. The standard theory of diffusive shock acceleration predicts that the energetic-particle energy spectrum, in the region of shocked plasma, is a function of the plasma density jump. But because of the interaction of the shock with plasma turbulence, the jump in plasma density varies in time and from place to place on the shock front. Here we show that for reasonable parameters, the shape of the energetic-particle energy spectra downstream of any given shock is nearly independent of location along the shock front, even though the density jump varies. This is because energetic particles are mobile and sample many turbulent fluctuations during their acceleration. This result holds for shocks having smaller scale ripples than the large-scale radius of curvature (Dc) of the shock. Thus, it applies to the interpretation of spacecraft observations of traveling interplanetary shocks provided the spacecraft separation is less than Dc. This result is confirmed with simple analytic considerations and numerical simulations that solve the combined magnetohydrodynamic equations for a plasma and energetic test particles using the well-known Parker transport equation. This conclusion is further supported by our analysis of ACE and Geotail observations of a few interplanetary shocks.

  19. Particle Acceleration in the Low Corona Over Broad Longitudes: Coupling Between 3D Magnetohydrodynamic and Energetic Particle Models

    NASA Astrophysics Data System (ADS)

    Gorby, M.; Schwadron, N.; Lee, M. A.; Booth, A. C.; Spence, H.; Torok, T.; Downs, C.; Lionello, R.; Linker, J.; Titov, V. S.; Mikic, Z.; Riley, P.; Desai, M. I.; Dayeh, M. A.; Kozarev, K. A.

    2013-12-01

    Recent work on the coupling between 3D energetic particle models (e.g., the Energetic Particle Radiation Environment Model, EPREM) and magnetohydrodynamic (MHD) models of Coronal Mass Ejections (CMEs, e.g., the PSI MAS model) has demonstrated the efficacy of compression regions in front of fast CMEs for particle acceleration from remarkably low in the corona (3-6 solar radii). Typically particle acceleration becomes rapid beyond 3Rs and often in regions where compression regions have not yet formed active shocks. The challenge for forming large SEP events in such compression-acceleration scenarios is to have enhanced scattering within the acceleration region while also allowing for efficient escape of accelerated particles downstream (away from the Sun) from the compression region. Simulations show rapid particle acceleration in the range of 3-8 Rs over a broad longitudinal region (80°) resulting from the pile-up of magnetic flux in the compression and the subsequent expansion of these fields. These results have important implications for multi-instrument observations that will allow Solar Probe Plus and Solar Orbiter to test the developing paradigm of SEP acceleration and transport from coronal compressions. We present here recent coupled simulations for SEP acceleration and transport, including energetic particle and CME plasma profiles. The broadness of the longitudinal profile from such events may be a key observational test of compression acceleration in the low corona.

  20. Monitoring solar energetic particles with an armada of European spacecraft and the new automated SEPF (Solar Energetic Proton Fluxes) Tool

    NASA Astrophysics Data System (ADS)

    Sandberg, I.; Daglis, I. A.; Anastasiadis, A.; Balasis, G.; Georgoulis, M.; Nieminen, P.; Evans, H.; Daly, E.

    2012-01-01

    Solar energetic particles (SEPs) observed in interplanetary medium consist of electrons, protons, alpha particles and heavier ions (up to Fe), with energies from dozens of keVs to a few GeVs. SEP events, or SEPEs, are particle flux enhancements from background level (< 1 pfu, particle flux unit = particle cm-2sr-1s-1) to several orders of magnitude in the MeV range, and lasting from several hours to a few days. Intense SEPEs can reach fluence values as high as 1010 protons cm-2 for E > 30 MeV. The main part of SEPEs results from the acceleration of particles either by solar flares and/or by interplanetary shocks driven by Coronal Mass Ejections (CMEs); these accelerated particles propagate through the heliosphere, traveling along the interplanetary magnetic field (IMF). SEPEs show significant variability from one event to another and are an important part of space weather, because they pose a serious health risk to humans in space and a serious radiation hazard for the spacecraft hardware which may lead to severe damages. As a consequence, engineering models, observations and theoretical investigations related to the high energy particle environment is a priority issue for both robotic and manned space missions. The European Space Agency operates the Standard Radiation Environment Monitor (SREM) on-board six spacecraft: Proba-1, INTEGRAL, Rosetta, Giove-B, Herschel and Planck, which measures high-energy protons and electrons with a fair angular and spectral resolution. The fact that several SREM units operate in different orbits provides a unique chance for comparative studies of the radiation environment based on multiple data gathered by identical detectors. Furthermore, the radiation environment monitoring by the SREM unit onboard Rosetta may reveal unknown characteristics of SEPEs properties given the fact that the majority of the available radiation data and models only refer to 1AU solar distances. The Institute for Space Applications and Remote Sensing of

  1. Quasilinear Line Broadened Model for Energetic Particle Transport

    NASA Astrophysics Data System (ADS)

    Ghantous, Katy; Gorelenkov, Nikolai; Berk, Herbert

    2011-10-01

    We present a self-consistent quasi-linear model that describes wave-particle interaction in toroidal geometry and computes fast ion transport during TAE mode evolution. The model bridges the gap between single mode resonances, where it predicts the analytically expected saturation levels, and the case of multiple modes overlapping, where particles diffuse across phase space. Results are presented in the large aspect ratio limit where analytic expressions are used for Fourier harmonics of the power exchange between waves and particles, . Implemention of a more realistic mode structure calculated by NOVAK code are also presented. This work is funded by DOE contract DE-AC02-09CH11466.

  2. A New Multiphase Model for Simulating Energetically Driven Particles

    SciTech Connect

    Stevens, D E; Murphy, M J

    2010-02-02

    The proper representation of particulate phenomena is important for the simulation of many non-ideal particle loaded explosives. These explosives present severe numerical difficulties to simulate because numerical approaches for packed particle beds often behave poorly for the dilute regime and the reverse is often true for methods developed for the dilute regime. This paper presents a multiphase framework for the simulation of these non-ideal explosives that accurately accounts for the particulate behavior in both of these regimes. The capability of this framework is enhanced by the use of prescribed PDF methods for both particle size distributions and the representation of chemical processes. We have validated this framework using several experimental methods that accommodate the separation of momentum flux measurements in two-phase blast flows.

  3. Energetic particle studies at Mars by SLED on Phobos 2.

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Afonin, V. V.; Gringauz, K. I.; Kecskemety, K.; Keppler, E.; Kirsch, E.; Richter, A.; Rusznyak, P.; Schwingenschuh, K.; O'Sullivan, D.; Somogyi, A. J.; Szabo, L.; Thompson, A.; Varga, A.; Yeroshenko, Ye.; Witte, M.

    1992-09-01

    A preliminary overview of particle records obtained by the SLED instrument on Phobos 2, Feb-Mar, 1989 during Mars encounter, is presented. Data obtained while in close elliptical orbit around the planet (pericenter <900 km), in both spin and three axis stabilised mode, display evidence of energy related particle shadowing by the body of Mars. Flux enhancements, inside the magnetopause, in the approximate range 30 - 350 keV, recorded in the same general location at <900 km above Mars over an 8 day period during three consecutive elliptical orbits, are described. Possible explanations of these enhancements include the presence of quasi-trapped radiation at the planet and the detection of the propagation of accelerated particles along the boundary of the magnetopause from the day to the night side of Mars.

  4. Modeling of long range frequency sweeping for energetic particle modes

    SciTech Connect

    Nyqvist, R. M.; Breizman, B. N.

    2013-04-15

    Long range frequency sweeping events are simulated numerically within a one-dimensional, electrostatic bump-on-tail model with fast particle sources and collisions. The numerical solution accounts for fast particle trapping and detrapping in an evolving wave field with a fixed wavelength, and it includes three distinct collisions operators: Drag (dynamical friction on the background electrons), Krook-type collisions, and velocity space diffusion. The effects of particle trapping and diffusion on the evolution of holes and clumps are investigated, and the occurrence of non-monotonic (hooked) frequency sweeping and asymptotically steady holes is discussed. The presented solution constitutes a step towards predictive modeling of frequency sweeping events in more realistic geometries.

  5. Plasma and energetic particle structure upstream of a quasi-parallel interplanetary shock

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Wenzel, K.-P.; Sanderson, T. R.; Van Nes, P.; Smith, E. J.; Tsurutani, B. T.; Scudder, J. D.

    1984-01-01

    ISEE 1, 2 and 3 data from 1978 on interplanetary magnetic fields, shock waves and particle energetics are examined to characterize a quasi-parallel shock. The intense shock studied exhibited a 640 km/sec velocity. The data covered 1-147 keV protons and electrons and ions with energies exceeding 30 keV in regions both upstream and downstream of the shock, and also the magnitudes of ion-acoustic and MHD waves. The energetic particles and MHD waves began being detected 5 hr before the shock. Intense halo electron fluxes appeared ahead of the shock. A closed magnetic field structure was produced with a front end 700 earth radii from the shock. The energetic protons were cut off from the interior of the magnetic bubble, which contained a markedly increased density of 2-6 keV protons as well as the shock itself.

  6. Trapped Particle Instabilities in the Kinetically Stabilized Tandem Mirror

    NASA Astrophysics Data System (ADS)

    Pratt, J.; Berk, H. L.; Horton, W.

    2009-05-01

    The kinetically stabilized tandem mirror (KSTM) is an innovative design to stabilize MHD modes in an axially symmetric tandem mirror machine (Post, J. Fus. Energy 2007). Originally proposed by Ryutov (Ryutov, Proc. of Course and Workshop, Varenna, Italy, 1987), this stabilizer has been empirically verified in the Gas Dynamic Trap (Ivanov, Anakeev et.al. Trans. Fusion Technology. 39, 127, 2001). The KSTM uses the momentum flux of escaping particles that sample good magnetic-field-line-curvature region outside the central confinement region. Charged ion beams at relatively low energy are externally injected from the ends into the expander region at an energy that is consistent with a stable MHD prediction and acceptable power loss for fusion. If stable, the KSTM would be extremely useful for limiting radial diffusion since the chaotic step size is minimized. We confirm that MHD stability is achieved in the KSTM. We examine the effect of the trapped particle instability discussed in Berk, Rosenbluth, et al. Sov. J. Plasma Phys. 1983 on overall stability. In this case stability is very sensitive to the electron connection between the stabilizer and the end plug.

  7. The trapped-particle instability in the Boeing 1kW FEL oscillator

    SciTech Connect

    Ramos, L.; Blau, J.; Colson, W.B.

    1995-12-31

    The new design for the Boeing High Average Power Free Electron Laser will operate at 1KW average power (0.63 {mu}m) with a peak current of 132A. Simulations are used to investigate the trapped-particle instability and diffraction effects. Incorporating large desynchronism may prove to be a useful method of controlling the trapped-particle instability.

  8. Energetic charged particles in the magnetosphere of neptune.

    PubMed

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

    1989-12-15

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

  9. Cluster Observations of Energetic Particles at the Reconnecting Magnetopause

    NASA Astrophysics Data System (ADS)

    Lee, S.; Zhang, H.; Glassmeier, K.; Daly, P. W.; Reme, H.

    2011-12-01

    We present preliminary results on a magnetic reconnection event observed by the Cluster spacecraft at the dayside magnetopause. Cluster 3 crossed the magnetopause at (X, Y, Z) = (8.3, 1.3, 4.5) RE GSM while travelling outbound in the northern hemisphere on March 5, 2007. Bursty high speed flows (Vz~250 km/s, Vx~-200 km/s) were observed from 18:55 UT to 19:10 UT. Meanwhile, energetic protons (> 30 keV) and Oxygen ions were observed by the RAPID instrument. During this time interval, the IMF was southward with (Bx, By, Bz) = (-4, 0, -4) nT GSM and the solar wind speed was -400 km/s. Cold plasmashperic materials were accelerated by the magnetic reconnection. The ion pitch angle measured by the CIS instrument changed from 0 to 180 degree, indicating that the direction of the magnetic field changed from northward to southward, i.e., the spacecraft passed the reconnection outflow region from the magnetospheric side to the magnetosheath side. The energy spectra of ions before and during the outflow region crossing have been investigated. The role played by cold ions in the reconnection process has been discussed.

  10. Energetic particle sounding of the magnetopause: A contribution by Cluster/RAPID

    NASA Astrophysics Data System (ADS)

    Zong, Q.-G.; Fritz, T. A.; Spence, H.; Oksavik, K.; Pu, Z.-Y.; Korth, A.; Daly, P. W.

    2004-04-01

    In this paper we present new results using Cluster/Research with Adaptive Particle Imaging Detectors (RAPID) energetic particle observations to remotely sound the high-latitude magnetopause in three dimensions. We demonstrate that energetic particle flux variations in the vicinity of the magnetopause (inside the magnetosphere) are mainly modulated by the absorbing magnetopause during quiet geomagnetic conditions. Less than two gyro radii from an absorbing boundary a trapped particle distribution becomes nongyrotropic, as particles start to encounter the boundary. Knowing the magnetic field and the particle mass and energy, the direction and distance to the magnetopause can be derived by examining the azimuthal distribution of locally mirroring particles. Combining observations from three nearby spacecraft gives a three-dimensional, local picture of the magnetopause surface. We exploit anisotropic ion distributions to determine magnetopause distances, orientations, and structures in the interval from 1320 to 1420 UT on 14 January 2001 for the three Cluster spacecraft (Rumba, Samba, and Tango) located on the duskside (at ˜1700 MLT) high-latitude region. The results clearly illustrate that the magnetopause ion sounding technique as proposed by [1979], [1982], and [2000] can be used to remotely study the three-dimensional orientation and location of the magnetopause surface and the gradient variation of the plasma parameters. Intercomparison between energetic particle sounding distance and simultaneous plasma and magnetic field measurements suggests that solar wind plasma can penetrate more than ≈1000 km deeper than the trapping boundary. The fluxes of different ion species are proportional to the distance from the magnetopause, with a correlation coefficient of 0.7 to 0.8. The energetic proton flux gradient as a function of distance from the magnetosphere is about 100 particles cm-2 s-1 sr-1 per kilometer. In contrast, the solar wind plasma density is found to be

  11. Identifying the Real Seed Population for Shock Accelerated Energetic Particles: Recent Observational Progress

    NASA Astrophysics Data System (ADS)

    Mason, G. M.; Mazur, J. E.; Desai, M. I.; Dwyer, J. R.

    2002-12-01

    Gradual solar energetic particle events, traveling interplanetary shocks, and corotating interaction regions are examples of shock acceleration of particles in the heliosphere. Although shock acceleration of particles has long been the subject of theoretical investigation, nevertheless key energetic particle properties such as intensity and spectral index are only roughly correlated with predictions of the theories. This may be due to limitations of the theories, but it may also be due to a lack of understanding of properties of the seed population. Recent measurements have shown that trace elements in the thermal plasma (e.g. singly ionized He, and 3He) often show dramatic enhancements in the energetic particle population. Although the observational picture is far from complete, it appears that the injection threshold in these events is about 1.5-2 times the solar wind speed. In this range, multiple particle sources are present, including solar wind suprathermals, pick up ions, and remnant material from prior shocks and impulsive events. Thus, the enhancements are not due to properties of the shock acceleration, but rather are primarily due to the properties of the seed population. This points to new opportunities for theoretical and experimental investigations to quantitatively model shock accelerated particle populations using realistic seed populations.

  12. Localized enhancements of energetic particles at oblique collisionless shocks

    NASA Astrophysics Data System (ADS)

    Fraschetti, F.; Giacalone, J.

    2015-04-01

    We investigate the spatial distribution of charged particles accelerated by non-relativistic oblique fast collisionless shocks using three-dimensional test-particle simulations. We find that the density of low-energy particles exhibits a localized enhancement at the shock, resembling the `spike' measured at interplanetary shocks. In contrast to previous results based on numerical solutions to the focused transport equation, we find a shock spike for any magnetic obliquity, from quasi-perpendicular to parallel. We compare the pitch-angle distribution with respect to the local magnetic field and the momentum distribution far downstream and very near the shock within the spike; our findings are compatible with predictions from the scatter-free shock drift acceleration limit in these regions. The enhancement of low-energy particles measured by Voyager 1 at solar termination shock is comparable with our profiles. Our simulations allow for predictions of suprathermal protons at interplanetary shocks within 10 solar radii to be tested by Solar Probe mission. They also have implications for the interpretation of ions accelerated at supernova remnant shocks.

  13. High-energy particle production in solar flares (SEP, gamma-ray and neutron emissions). [solar energetic particles

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1987-01-01

    Electrons and ions, over a wide range of energies, are produced in association with solar flares. Solar energetic particles (SEPs), observed in space and near earth, consist of electrons and ions that range in energy from 10 keV to about 100 MeV and from 1 MeV to 20 GeV, respectively. SEPs are directly recorded by charged particle detectors, while X-ray, gamma-ray, and neutron detectors indicate the properties of the accelerated particles (electrons and ions) which have interacted in the solar atmosphere. A major problem of solar physics is to understand the relationship between these two groups of charged particles; in particular whether they are accelerated by the same mechanism. The paper reviews the physics of gamma-rays and neutron production in the solar atmosphere and the method by which properties of the primary charged particles produced in the solar flare can be deduced. Recent observations of energetic photons and neutrons in space and at the earth are used to present a current picture of the properties of impulsively flare accelerated electrons and ions. Some important properties discussed are time scale of production, composition, energy spectra, accelerator geometry. Particular attention is given to energetic particle production in the large flare on June 3, 1982.

  14. Energetic particle observations at the Helios 1 spacecraft of shocks associated with coronal mass ejections

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Von Rosenvinge, T. T.; Mcguire, R. E.

    1990-01-01

    Energetic particle data from the Helios 1 spacecraft have been used to study the particles associated with 26 coronal mass ejection (CME)/shock pairs. The particle events are divided into four classes on the basis of the relative intensities of their prompt and shock-associated components. Events in group 1 have strong prompt and shock components and are associated with energetic CMEs originating, most commonly, with central meridian flares. Group 2 events characteristically have strong prompt components and weaker shock components and are associated with western hemisphere (i.e., favorably located) flares. Group 3 consists of events with absent prompt components and strong shock components; the CMEs probably originate in disappearing filament events near central meridian. Group 4 events show no particle enhancements and are associated with slow CMEs and slow shocks.

  15. Ionic charge state distribution of helium, carbon, oxygen, and iron in an energetic storm particle enhancement

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Klecker, B.; Hoefner, H.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.

    1982-01-01

    An analysis is presented of the ionic charge state distribution of He, C, O and Fe in the energetic storm particle event of September 28-29, 1978. Data were obtained with the ULEZEQ electrostatic analyzer-proportional counter on board the ISEE 3 spacecraft. The He(+)/He(++) ratio between 0.4 and 1 MeV/n is shown to be significantly lower during the energetic storm particle event than during the preceding period of solar flare particle enhancement, with a temporal evolution similar to that of the Fe/He ratio as reported by Klecker et al. (1981). Increases in the mean charge state for oxygen by about 3% and for iron by about 16% are also noted. The temporal variations in charge states are accounted for in terms of first-order Fermi acceleration of the pre-existing solar flare particles by a propagating interplanetary shock wave.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  17. Nighttime ionization by energetic particles at Wallops Island in the altitude region 120 to 200 km

    NASA Technical Reports Server (NTRS)

    Voss, H. D.; Smith, L. G.

    1979-01-01

    Five Nike Apache rockets, each including an energetic particle spectrometer and an electron density-electron temperature experiment, have been launched from Wallops Island (L = 2.6) near midnight under varying geomagnetic conditions. On the most recent of these (5 January 1978) an additional spectrometer with a broom magnet, and a 391.4 nm photometer were flown. The data from this flight indicate that the energetic particle flux consists predominantly of protons, neutral hydrogen and possibly other energetic nuclei. The energy spectrum becomes much softer and the flux more intense with increasing Kp for 10-100 keV. The pitch angle distribution at 180 km is asymmetrical with a peak at 90 deg indicating that the majority of particles are near their mirroring altitude. Ionization rates are calculated based on the measured energy spectrum and mirror height distribution. The resulting ionization rate profile is found to be nearly constant with altitude in the region 120 to 200 km. The measured energetic particle flux and calculated ionization rate from the five flights are found to vary with magnetic activity (based on the Kp and Dst indexes) in the same way as the independently derived ionization rates deduced from the electron density profile.

  18. Theory on excitations of drift Alfvén waves by energetic particles. I. Variational formulation

    SciTech Connect

    Zonca, Fulvio; Chen, Liu

    2014-07-15

    A unified theoretical framework is presented for analyzing various branches of drift Alfvén waves and describing their linear and nonlinear behaviors, covering a wide range of spatial and temporal scales. Nonlinear gyrokinetic quasineutrality condition and vorticity equation, derived for drift Alfvén waves excited by energetic particles in fusion plasmas, are cast in integral form, which is generally variational in the linear limit; and the corresponding gyrokinetic energy principle is obtained. Well known forms of the kinetic energy principle are readily recovered from this general formulation. Furthermore, it is possible to demonstrate that the general fishbone like dispersion relation, obtained within the present theoretical framework, provides a unified description of drift Alfvén waves excited by energetic particles as either Alfvén eigenmodes or energetic particle modes. The advantage of the present approach stands in its capability of extracting underlying linear and nonlinear physics as well as spatial and temporal scales of the considered fluctuation spectrum. For these reasons, this unified theoretical framework can help understanding experimental observations as well as numerical simulation and analytic results with different levels of approximation. Examples and applications are given in Paper II [F. Zonca and L. Chen, “Theory on excitations of drift Alfvén waves by energetic particles. II. The general fishbone-like dispersion relation,” Phys. Plasmas 21, 072121 (2014)].

  19. Probing the magnetic topologies of magnetic clouds by means of solar energetic particles

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.; Reames, D. V.

    1991-01-01

    Solar energetic particles (SEPs) have been used as probes of magnetic cloud topologies. The rapid access of SEPs to the interiors of many clouds indicates that the cloud field lines extend back to the sun and hence are not plasmoids. The small modulation of galactic cosmic rays associated with clouds also suggests that the magnetic fields of clouds are not closed.

  20. User's guide to data obtained by the Aerospace Corporation energetic particle spectrometer on ATS-6

    NASA Technical Reports Server (NTRS)

    Paulikas, G. A.; Hilton, H. H.

    1977-01-01

    Descriptions of the energetic particle detector are offered with calibration data, as part of a user's guide to the data obtained by ATS 6. Information on instrumental and operational anomalies and a description of the procedures used to reduce the data are also presented along with a description of the format of the data.

  1. Energetic particles and coronal mass ejections in the high latitude heliosphere: Ulysses-LET observations

    SciTech Connect

    Bothmer, V.; Marsden, R. G.; Sanderson, T. R.; Trattner, K. J.; Wenzel, K.-P.; Balogh, A.; Forsyth, R. J.; Goldstein, B. E.; Uchida, Y.; Hudson, H. S.

    1996-07-20

    We have investigated energetic ions of non-corotating nature in the high latitude heliosphere. Major particle events were observed by Ulysses up to latitudes of 60 deg. S. All were associated with passage of coronal mass ejections (CMEs) over the spacecraft. The relationship of these events with solar activity was investigated using Yohkoh soft X-ray images.

  2. Energetic particles and ionization in the nighttime middle and low latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Voss, H. D.; Smith, L. G.

    1977-01-01

    Seven Nike Apache rockets, each equipped with an energetic particle spectrometer (12 E 80 keV) and electron-density experiments, were launched from Wallops Island, Virginia and Chilca, Peru, under varying geomagnetic conditions near midnight. At Wallops Island the energetic particle flux (E 40 keV) is found to be strongly dependent on Kp. The pitch-angle distribution is asymmetrical about a peak at 90 D signifying a predominately quasi-trapped flux and explaining the linear increase of count rate with altitute in the altitude region 120 to 200 km. The height-averaged ionization rates derived from the electron-density profiles are consistent with the rates calculated from the observed total particle flux for magnetic index Kp 3. In the region 90 to 110 km it is found that the nighttime ionization is primarily a result of Ly-beta radiation from the geocorona and interplanetary hydrogen for even very disturbed conditions. Below 90 km during rather disturbed conditions energetic electrons can be a significant ionization source. Two energetic particle precipitation zones have been identified at midlatitudes.

  3. Particle size and energetics of gouge from earthquake rupture zones.

    PubMed

    Wilson, Brent; Dewers, Thomas; Reches, Ze'ev; Brune, James

    2005-04-01

    Grain size reduction and gouge formation are found to be ubiquitous in brittle faults at all scales, and most slip along mature faults is observed to have been localized within gouge zones. This fine-grain gouge is thought to control earthquake instability, and thus understanding its properties is central to an understanding of the earthquake process. Here we show that gouge from the San Andreas fault, California, with approximately 160 km slip, and the rupture zone of a recent earthquake in a South African mine with only approximately 0.4 m slip, display similar characteristics, in that ultrafine grains approach the nanometre scale, gouge surface areas approach 80 m2 g(-1), and grain size distribution is non-fractal. These observations challenge the common perception that gouge texture is fractal and that gouge surface energy is a negligible contributor to the earthquake energy budget. We propose that the observed fine-grain gouge is not related to quasi-static cumulative slip, but is instead formed by dynamic rock pulverization during the propagation of a single earthquake. PMID:15815626

  4. Long-term energetic-particle databases from geosynchronous and GPS orbits

    SciTech Connect

    Reedy, R.C.; Belian, R.D.; Clayton, T.E.

    1998-03-01

    The Los Alamos National Laboratory has flown thirteen energetic particle instruments on geosynchronous satellites since 1976 and on seven GPS satellites since 1983. These instruments measure electrons and protons over a wide range of energies. The various instruments and the particles and energies that they measure are described. The measured fluxes are stored at Los Alamos in several databases that are available to outside users.

  5. RAPID: The imaging energetic particle spectrometer on Cluster

    NASA Technical Reports Server (NTRS)

    Wilken, B.; Guettler, W.; Korth, A.; Livi, S.; Weiss, W.; Gliem, F.; Muellers, A.; Rathje, R.; Fritz, T. A.; Fennell, J. F.

    1993-01-01

    The RAPID spectrometer for the Cluster mission, an advanced particle detector for the analysis of suprathermal plasma distributions in the energy range from 20 to 400 keV and from 2 keV/nuc to 1500 keV for electrons and ions, respectively, is presented. Novel detector concepts in combination with pinhole acceptance permit the measurement of angular distributions over a range of 180 deg in polar angle for either species. The detection principle for the ionic component is based on a two dimensional analysis of a particle's velocity and energy. Electrons are identified by the well known energy range relationship. The detection techniques are described and selected areas in geospace are used to highlight the scientific objectives of this investigation.

  6. Erosion processes due to energetic particle-surface interaction

    SciTech Connect

    Schmid, K.; Roth, J.

    2010-05-20

    The interaction of the fast particles from the hot plasma of a magnetic confinement fusion experiment with the first wall is one of the most challenging problems toward the realization of a fusion power plant. The erosion of the first wall by the fast particles leads to life time limitations and the radiative cooling of the plasma by the eroded impurity species lowers the energy confinement. Apart from these obvious consequences also the trapping of large quantities of the fuelling species (deuterium and tritium) in re-deposited layers of the eroded species poses a problem due to accumulation of large radiative inventories and plasma fuelling inefficiency. The source of all these challenges is the erosion of first wall components due to physical sputtering, chemical erosion and radiation enhanced sublimation. This paper will give an overview about the physical principles behind these erosion channels.

  7. The TP-3 spectrometer of energetic charged particles

    NASA Astrophysics Data System (ADS)

    Fischer, S.; Lutsenko, V.,; Plch, J.

    Design and performance features and test data for the TP-3 instrument for measuring the chemical and isotopic composition, energy spectra, time variations and the spatial distribution of ion fluxes as part of the Intershock project are described. The instrument was based on the designs of similar instruments carried on the Prognoz-5 and -6 and Intercosmos-17 spacecraft. The flux data will cover particles with atomic numbers 1-28 possessing energies from one to several tens of MeV per nucleon. The TP-3 has a telescope with four Si detectors and a scintillation detector with active shielding. Details of the sampling procedures used to select pulse amplitudes for recording are delineated. Laboratory tests of the detector response to long-term exposure to 5.5 MeV alpha-particles, reverse currents and the maximum working voltage demonstrated the instrumental accuracy and durability for meeting the mission specifications.

  8. Energetic particle drift motions in the outer dayside magnetosphere

    SciTech Connect

    Buck, R.M.

    1987-12-01

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

  9. 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

  10. Parameter estimation of superdiffusive motion of energetic particles upstream of heliospheric shocks

    NASA Astrophysics Data System (ADS)

    Perri, Silvia; Zimbardo, Gaetano; Effenberger, Frederic; Fichtner, Horst

    2015-06-01

    Context. In-situ spacecraft observations recently suggested that the transport of energetic particles accelerated at heliospheric shocks can be anomalous, i.e. the mean square displacement can grow non-linearly in time. In particular, a new analysis technique has permitted the study of particle transport properties from energetic particle time profiles upstream of interplanetary shocks. Indeed, the time/spatial power laws of the differential intensity upstream of several shocks are indicative of superdiffusion. Aims: A complete determination of the key parameters of superdiffusive transport comprises the power-law index, the superdiffusion coefficient, the related transition scale at which the energetic particle profiles turn to decay as power laws, and the energy spectral index of the shock accelerated particles. Methods: Assuming large-scale spatial homogeneity of the background plasma, the power-law behaviour can been derived from both a (microscopic) propagator formalism and a (macroscopic) fractional transport equation. We compare the two approaches and find a relation between the diffusion coefficients used in the two formalisms. Based on the assumption of superdiffusive transport, we quantitatively derive these parameters by studying energetic particle profiles observed by the Ulysses and Voyager 2 spacecraft upstream of shocks in the heliosphere, for which a superdiffusive particle transport has previously been observed. Further, we have jointly studied the electron energy spectra, comparing the values of the spectral indices observed with those predicted by the standard diffusive shock acceleration theory and by a model based on superdiffusive transport. Results: For a number of interplanetary shocks and for the solar wind termination shock, for the first time we obtain the anomalous diffusion constants and the scale at which the probability of particle free paths changes to a power-law. The investigation of the particle energy spectra indicates that a

  11. First identification in energetic particles of characteristic plasma boundaries at Mars and an account of various energetic particle populations close to the planet

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S. M. P.; Afonin, V.; Yeroshenko, Ye.; Keppler, E.; Kirsch, E.; Schwingenschuh, K.

    1993-05-01

    Signatures of characteristic boundaries, interpreted to be the bow shock and magnetopause with, between them, the magnetosheath, were recorded for the first time in energetic particles (between 30 keV and 3.2 MeV) in the downstream nightside Martian environment by the SLED instrument aboard Phobos 2. Also, energetic particles, interpreted to be oxygen ions, were recorded by SLED at four distinct locations close to Mars. These include (a) anisotropic fluxes at the terminator shocks with energies of up to at least 72 keV; (b) anisotropic fluxes with energies of up to at least 225 keV inside the magnetopause, at a height above the planet of approximately 900 km in the subsolar part of the magnetosphere; (c) fluxes with energies of up to at least 3.2 MeV in the flanks of the magnetosheath displaying quasi-periodic variations (period approximately 45 min) which are synchronous across the recorded energy spectrum and correlated in time with changes in the local magnetic field; and (d) beams of oxygen ions with energies of up to at least 55 keV traveling out along open field lines in the magnetotail with, in some cases, a suggestion of confinement close to the neutral sheet. A preliminary discussion is provided concerning the energization of the various populations of particles identified.

  12. Interaction between Two Coronal Mass Ejections in the 2013 May 22 Large Solar Energetic Particle Event

    NASA Astrophysics Data System (ADS)

    Ding, Liu-Guan; Li, Gang; Jiang, Yong; Le, Gui-Ming; Shen, Cheng-Long; Wang, Yu-Ming; Chen, Yao; Xu, Fei; Gu, Bin; Zhang, Ya-Nan

    2014-10-01

    We investigate the eruption and interaction of two coronal mass ejections (CMEs) during the large 2013 May 22 solar energetic particle event using multiple spacecraft observations. Two CMEs, having similar propagation directions, were found to erupt from two nearby active regions (ARs), AR11748 and AR11745, at ~08:48 UT and ~13:25 UT, respectively. The second CME was faster than the first CME. Using the graduated cylindrical shell model, we reconstructed the propagation of these two CMEs and found that the leading edge of the second CME caught up with the trailing edge of the first CME at a height of ~6 solar radii. After about two hours, the leading edges of the two CMEs merged at a height of ~20 solar radii. Type II solar radio bursts showed strong enhancement during this two hour period. Using the velocity dispersion method, we obtained the solar particle release (SPR) time and the path length for energetic electrons. Further assuming that energetic protons propagated along the same interplanetary magnetic field, we also obtained the SPR time for energetic protons, which were close to that of electrons. These release times agreed with the time when the second CME caught up with the trailing edge of the first CME, indicating that the CME-CME interaction (and shock-CME interaction) plays an important role in the process of particle acceleration in this event.

  13. INTERACTION BETWEEN TWO CORONAL MASS EJECTIONS IN THE 2013 MAY 22 LARGE SOLAR ENERGETIC PARTICLE EVENT

    SciTech Connect

    Ding, Liu-Guan; Xu, Fei; Gu, Bin; Zhang, Ya-Nan; Li, Gang; Jiang, Yong; Le, Gui-Ming; Shen, Cheng-Long; Wang, Yu-Ming; Chen, Yao

    2014-10-01

    We investigate the eruption and interaction of two coronal mass ejections (CMEs) during the large 2013 May 22 solar energetic particle event using multiple spacecraft observations. Two CMEs, having similar propagation directions, were found to erupt from two nearby active regions (ARs), AR11748 and AR11745, at ∼08:48 UT and ∼13:25 UT, respectively. The second CME was faster than the first CME. Using the graduated cylindrical shell model, we reconstructed the propagation of these two CMEs and found that the leading edge of the second CME caught up with the trailing edge of the first CME at a height of ∼6 solar radii. After about two hours, the leading edges of the two CMEs merged at a height of ∼20 solar radii. Type II solar radio bursts showed strong enhancement during this two hour period. Using the velocity dispersion method, we obtained the solar particle release (SPR) time and the path length for energetic electrons. Further assuming that energetic protons propagated along the same interplanetary magnetic field, we also obtained the SPR time for energetic protons, which were close to that of electrons. These release times agreed with the time when the second CME caught up with the trailing edge of the first CME, indicating that the CME-CME interaction (and shock-CME interaction) plays an important role in the process of particle acceleration in this event.

  14. Acceleration of energetic particles. [in collisionless shock waves in interstellar space

    NASA Technical Reports Server (NTRS)

    Forman, M. A.; Webb, G. M.

    1985-01-01

    Acceleration of some particles from the background plasma to highly superthermal energies is a common feature of collisionless shocks in interplanetary space. The complete in situ measurements of bulk flows, thermal plasma, electromagnetic waves and energetic particles available for interplanetary shocks both suggest and test the models of shock acceleration in the solar system and the rest of the universe. This tutorial will review the present state of shock acceleration theory. Scatter-free acceleration by grad B drift in the plasma electric field E = -V x B/c, and diffusive acceleration resulting from scattering by Alfven waves in the plasma on both sides of the shock are discussed. The diffusive theory in simple steady state gives power-law spectra, but also shows the effects of time-dependent shocks and injection rates, escape and other losses, the self-consistent Alfven wave spectra, and plasma flow fields affected by diffusive energetic particle acceleration.

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

    SciTech Connect

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

    1982-01-29

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

  16. Anthropogenic trigger of substorms and energetic particles precipitations

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. D.; Ruzhin, Yu. Ya.

    2014-12-01

    The high-frequency (HF) emission in near-Earth space from various powerful transmitters (radio communications, radars, broadcasting, universal time and navigation stations, etc.) form an integral part of the modern world that it cannot do without. In particular, special-purpose research facilities equipped with powerful HF transmitters are used successfully for plasma experiments and local modification of the ionosphere. In this work, we are using the results of a complex space-ground experiment to show that exposure of the subauroral region to HF emission can not only cause local changes in the ionosphere, but can also trigger processes in the magnetosphere-ionosphere system that result in intensive substorm activity (precipitations of high-energy particles, aurorae, significant variations in the ionospheric parameters and, as a consequence, in radio propagation conditions).

  17. Energetic particle phase space densities at Saturn: Cassini observations and interpretations

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    Saturn's magnetosphere has been studied extensively by the Cassini spacecraft during the last 6 years. We present mission-averaged energetic proton and electron measurements obtained by the MIMI/LEMMS instrument onboard Cassini in an energy range from several 10 keV to several 10 MeV separated by equatorial pitch angle. We discuss the resulting radial profiles and energy spectra. The measured intensities are converted to phase space densities. The distribution of energetic particles is governed by a large variety of processes. For instance, moons absorb energetic particles, creating macrosignatures or microsignatures. We have found that the moon Rhea is partly responsible for a change in gradient of electron phase space densities. We show that, in contrast to larger distances, the particle distribution for L < 8 is not driven by radial diffusion alone. There, the particle profiles are significantly modified due to Saturn's Neutral Torus, plasma environment, E ring, injection events, and cosmic ray albedo neutron decay. Large parts of our analysis are focused near L = 7. There, protons are lost within the Neutral Torus and not the E ring. For electrons, we find that these two losses are of comparable rate but have discovered that neither process is the dominant driver of loss. We point out that intensity measured by a energy channel, such as in a particle instrument, can actually increase in the region of ring and torus instead of decrease. The importance of injection events is shown to be at least of similar importance as radial diffusion.

  18. The formation of molecular hydrogen from water ice in the lunar regolith by energetic charged particles

    NASA Astrophysics Data System (ADS)

    Jordan, A. P.; Stubbs, T. J.; Joyce, C. J.; Schwadron, N. A.; Spence, H. E.; Wilson, J. K.

    2013-06-01

    On 9 October 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) mission impacted a spent Centaur rocket into the permanently shadowed region (PSR) within Cabeus crater and detected water vapor and ice, as well as other volatiles, in the ejecta plume. The Lyman Alpha Mapping Project (LAMP), a far ultraviolet (FUV) imaging spectrograph on board the Lunar Reconnaissance Orbiter (LRO), observed this plume as FUV emissions from the fluorescence of sunlight by molecular hydrogen (H2) and other constituents. Energetic charged particles, such as galactic cosmic rays (GCRs) and solar energetic particles (SEPs), can dissociate the molecules in water ice to form H2. We examine how much H2can be formed by these types of particle radiation interacting with water ice sequestered in the regolith within PSRs, and we assess whether it can account for the H2 observed by LAMP. To estimate H2formation, we use the GCR and SEP radiation dose rates measured by the LRO Cosmic Ray Telescope for the Effects of Radiation (CRaTER). The exposure time of the ice is calculated by considering meteoritic gardening and the penetration depth of the energetic particles. We find that GCRs and SEPs could convert at least 1-7% of the original water molecules into H2. Therefore, given the amount of water detected by LCROSS, such particle radiation‒induced dissociation of water ice could likely account for a significant percentage (10-100%) of the H2measured by LAMP.

  19. Effects of The Encounter of A Solar Energetic Particle Event With Mercury

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Luhmann, J. G.; Johnson, R. E.; Chassefiere, E.

    In this work, we use a typical Solar Energetic Particles event observed at the Earth orbit and scaled to Mercury's orbit. We follow these energetic particles inside the Hermean magnetosphere. The model for the magnetosphere is deduced from Tsyga- nenko's Earth model (Tsyganenko, JGR 1996) extrapolated to Mercury following the measurements of the Hermean magnetosphere made by Mariner 10 (Luhmann et al., JGR 1998). For each of the four main species of ions which usually composed a SEP event, that is H+, He2+, O7+ and C6+, and for the electrons we follow inside the Her- mean magnetosphere thousands of particles launched from the magnetopause as far as either they leave the Hermean magnetosphere or reach the Hermean surface. From this calculation, we deduce the lifetime of these particles inside the magnetosphere and therefore confirm the existence of transfer radial ion and electron pockets (Luh- mann DPS 2001). We also estimate the flux of energetic particles reaching the surface in particular with respect to the Interplanetary Magnetic Field. We then calculate the importance of such encounter among the processes which contribute to generate the Hermean sodium neutral exosphere (Potter et al. 1986). We show in particular that most of the unexplained casual characteristics of this exosphere - peaks of emission on North and South daylight hemispheres (Killen et al. JGR 2001) and dawn/dusk asymmetries (Sprague et al. JGR 1998) - can be explained by such a type of encounter.

  20. STEREO solar energetic particle events: 2007-2011

    NASA Astrophysics Data System (ADS)

    Papaioannou, A.; Malandraki, O.; Heber, B.; Dresing, N.; Klein, K.; Gomez-Herrero, R.; Mewaldt, R. A.; Vainio, R. O.

    2012-12-01

    The STEREO (Solar TErrestrial RElations Observatory) mission employs two nearly identical space-based observatories - one ahead of Earth in its orbit (STEREO-A: STA), the other trailing behind (STEREO-B: STB) aiming at providing the first-ever stereoscopic measurements of the Sun. The intensities of SEP events are strongly affected by the properties of the interplanetary magnetic field that control the acceleration and propagation of particles throughout the heliosphere. The study of SEP events provides useful information on the physics of solar particle genesis, propagation and acceleration. Therefore the usage of STEREO recordings provides an unprecedented opportunity to identify the evolution of such events at different observing points within the heliosphere. In this work, two instruments onboard STEREO have been used in order to identify all SEP events observed within the rising phase of solar cycle 24 from 2007 to 2011, namely: the Low Energy Telescope (LET) and the Solar Electron Proton Telescope (SEPT). A scan over STEREO/LET protons within the energy range 6-10 MeV has been performed for each of the two STEREO spacecraft (i.e. STA & STB). We have tracked all enhancements that have been observed above the background level of this particular channel and cross checked with available lists on STEREO/ICMEs, SIRs and shocks as well as with the reported events via literature. Furthermore, parallel scanning of the STEREO/SEPT electrons in order to pin point the presence (or not) of an electron event has been performed in the energy range of 55-85 keV, for all of the aforementioned proton events, included in our lists. We provide the onset of all events for both protons and electrons and the relevant solar associations.

  1. Observation of MHD Instabilities Driven by Energetic Electrons in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Mitsutaka, Isobe; Kunihiro, Ogawa; Akihiro, Shimizu; Masaki, Osakabe; Shin, Kubo; Toi, K.; LHD Experiment Group

    2015-04-01

    Coherent magnetic fluctuations in an acoustic range of frequency have been regularly observed in low-density (ne < 0.2×1019 m-3) plasmas with strong second harmonic electron cyclotron resonance heating (ECRH) on the Large Helical Device. Hard X-ray measurements indicated that energetic electrons are generated in these ECRH discharges. The magnetic fluctuations are suppressed in higher density discharges where energetic electrons are not present. The ECRH power modulation experiment indicated that the observed magnetohydrodynamic (MHD) mode has an acoustic nature rather than an Alfvénic nature. supported by the Grant-in-Aid for Encouragement of Scientists from the Japan Society for the Promotion of Science (No. 20656150). This work was also partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics (NSFC: No. 11261140328 and NRF: No. 2012K2A2A6000443)

  2. Cosmic Ray and Solar Energetic Particle Observations In The 3-d Heliosphere Near Solar Maximum

    NASA Astrophysics Data System (ADS)

    McKibben, R. B.; Connell, J. J.; Lopate, C.

    Observations from the COSPIN High Energy Telescope during Ulysses recent fast lat- itude scan have provided the first latitudinal survey of intensities of cosmic rays and solar energetic particles near solar maximum. During the previous fast latitude scan near solar minimum, no significant solar energetic particle events were observed, but the galactic and anomalous component cosmic ray intensities showed small positive latitudinal gradients organized around a southwardly displaced heliospheric current sheet. The small size of the gradients, together with observation near the poles of 26-day intensity variations impressed by near-equatorial CIR-structures, led to the conclusion that latitudinal transport across the mean Parker spiral magnetic fields was much easier than had been expected prior to Ulysses observations. During the recently completed fast latitude scan near solar maximum, galactic cosmic rays could be ob- served only occasionally in the quiet times between frequent solar energetic particle events. When cosmic ray intensities could be observed, no measurable latitude gradi- ents were found, implying that modulation became much more spherically symmetric near solar maximum. From observations of the solar energetic particle intensities, we found that almost all large gradual events produced intensity increases both at Ulysses and at IMP-8 near Earth, regardless of the latitude or longitude of the spacecrafts relative to the initiating event in the corona. Most often the intensities at Ulysses and IMP-8 became comparable a few days after the onset of the event and remained nearly equal for the rest of the decay, which in some cases lasted as much as a full solar rota- tion. Both the cosmic ray and the solar energetic particle observations imply efficient latitudinal and cross-field transport of energetic particles even in the complex inter- planetary magnetic fields of solar maximum. Recent observations suggest that the solar polar coronal holes have

  3. A dynamical perspective on the energetic particles precipitation-middle atmosphere interaction

    NASA Astrophysics Data System (ADS)

    Karami, Khalil; Sinnhuber, Miriam; Versick, Stefan; Braesicke, Peter

    2015-04-01

    Energetic particles including protons, electrons and heavier ions, enter the Earth's atmosphere over polar region of both hemispheres, where the geomagnetic lines are considered to be open and connected to the interplanetary medium. This condition allows direct access for energetic particles of solar or galactic origin to directly deposit their own energy into the middle and upper atmosphere. Such particle precipitations can greatly disturb the chemical composition of the upper and middle atmosphere. At polar latitudes, these particles have the potential to penetrate from thermosphere deep into the mesosphere and in rare occasions into the stratosphere. The most important are changes to the budget of atmospheric nitric oxides, NOy, and to atmospheric reactive hydrogen oxides, HOx, which both contribute to ozone loss in the stratosphere and mesosphere. The chemistry-climate general circulation model ECHAM5/MESSy is used to investigate the impact of changed ozone concentration due to energetic particles precipitation on temperatures and wind fields. The simulated anomalies of both zonal mean temperature and zonal wind suggest that these changes are very unlikely to be caused in situ by ozone depletion and indirect dynamical condition is important. The results of our simulations suggests that ozone perturbation is a starting point for a chain of processes resulting in temperature and circulation changes in many areas of the atmosphere. Different dynamical analysis (e.g., frequency of sudden stratospheric warming, dates of stratospheric final warming, divergence of Eliassen-Palm flux and refractive index of planetary waves) are performed to investigate the impact of ozone anomaly originated from high energetic particle precipitation on middle atmospheric temperature and circulation.

  4. Energetic particle diffusion and the A ring: Revisiting noise from Cassini's orbital insertion

    NASA Astrophysics Data System (ADS)

    Crary, Frank; Kollmann, Peter

    2016-04-01

    Immediately following Cassini's orbital insertion on July 1, 2004 the Cassini spacecraft passed over the Saturn's main rings. In anticipation of the final phase of the Cassini mission, with orbits inside and over the main rings, we have re-examined data from the CAPS instrument taken during the orbital insertion period. One previously-neglected feature is the detector noise in the ELS sensor. This has proven to be a sensitive, relative measure of omni-directional energetic (>5 MeV) electron flux. The data are obtained at 31.25 ms time resolution, corresponding to 0.46 km spatial resolution. Over the A ring, the energetic electron flux was essentially zero (~3 counts per sample.) At the edge of the A ring, this dramatically increased to approximately 2500 counts per sample in the space of 17.5 km. We use these results to derive the energetic particle diffusion rate and the absorption (optical depth) of the ring.

  5. Origins of Suprathermal Seed Particles in Gradual Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Tylka, A. J.; Ko, Y.; Ng, C. K.; Wang, Y. M.; Dietrich, W. F.

    2013-05-01

    Gradual solar energetic particle (SEP) events are those in which ions are accelerated to their observed energies by interactions with a shock driven by a fast coronal mass-ejection (CME). Previous studies have shown that much of the observed event-to-event variability can be understood in terms of shock speed and evolution in the shock-normal angle. But an equally important factor, particularly for the elemental composition, is the origin of the suprathermal seed particles upon which the shock acts. To tackle this issue, we (1) use observed solar-wind speed, photospheric magnetograms, and the PFSS model to map the Sun-L1 interplanetary magnetic field (IMF) lines back to their source region on the Sun at the time of the SEP observations; and (2) then look for correlation between SEP composition (as measured by Wind and ACE at ~2-30 MeV/nucleon) and characteristics of the identified IMF-source regions. The study is based on 24 SEP events, identified as a statistically-significant increase in ~20 MeV protons and occurring in 1998 and 2003-2006, when the rate of CMEs was lower than in solar-maximum years and the field-line tracing is therefore more likely to be successful. In all cases, we are dealing with events in which the Fe/O enhancement is well-below the highly-enhanced values (~1) associated with "impulsive" SEP events, in which ions are believed to have attained their observed energies through magnetic reconnection, such as that which occurs in flares. We find that the gradual SEP Fe/O is correlated with the magnetic field near the IMF-source, with the largest enhancements occurring when the field is strong, due to the nearby presence of an active region. In these cases, other elemental ratios show a strong charge-to-mass (Q/M) ordering, at least on average, similar to that found in impulsive events. These results lead us to suggest that reconnection processes at footpoints near active regions bias the heavy-ion composition of suprathermal seed ions by

  6. Numerical study of particle-induced Rayleigh-Taylor instability: Effects of particle settling and entrainment

    NASA Astrophysics Data System (ADS)

    Chou, Yi-Ju; Shao, Yun-Chuan

    2016-04-01

    In this study, we investigate Rayleigh-Taylor instability in which the density stratification is caused by the suspension of particles in liquid flows using the conventional single-phase model and Euler-Lagrange (EL) two-phase model. The single-phase model is valid only when the particles are small and number densities are large, such that the continuum approximation applies. The present single-phase results show that the constant settling of the particle concentration restricts the lateral development of the vortex ring, which results in a decrease of the rising speed of the Rayleigh-Taylor bubbles. The EL model enables the investigation of particle-flow interaction and the influence of particle entrainment, resulting from local non-uniformity in the particle distribution. We compare bubble dynamics in the single-phase and EL cases, and our results show that the deviation between the two cases becomes more pronounced when the particle size increases. The main mechanism responsible for the deviation is particle entrainment, which can only be resolved in the EL model. We provide a theoretical argument for the small-scale local entrainment resulting from the local velocity shear and non-uniformity of the particle concentration. The theoretical argument is supported by numerical evidence. Energy budget analysis is also performed and shows that potential energy is released due to the interphase drag and buoyant effect. The buoyant effect, which results in the transformation of potential energy into kinetic energy and shear dissipation, plays a key role in settling enhancement. We also find that particle entrainment increases the shear dissipation, which in turn enhances the release of potential energy.

  7. The Energetic Particle Populations of the Distant Heliosphere

    SciTech Connect

    McDonald, F.B.; Cummings, A.C.; Stone, E.C.; Heikkila, B.C.; Lal, N.

    2004-09-15

    In late 2003 as Voyager 1 moves beyond 90 AU in the recovery phase of solar cycle 23, the effects of the termination shock (TS) and the heliosheath on particle transport are becoming more evident. There are now detectable fluxes of 2.5 - 70 MeV electrons but at low intensity levels that suggest they are heavily modulated in the heliosheath. The modulation of galactic and anomalous cosmic rays is significant but much smaller than observed at 1 AU. At V1 a large increase of MeV ions was observed with a flat energy spectra which persisted over a period of 6.5 months. A second event has now been in progress for some eight months. These ions appear to originate at the TS. At V2, 17 AU behind V1, there are a series of 8 increases of low energy ions that occur approximately every 140 days starting in late 2000. Many of these increases can be related to specific periods of high solar activity that occurred some 6 months earlier.

  8. Simple analytical solutions for spherically symmetric production and modulation of energetic solar particles

    NASA Technical Reports Server (NTRS)

    Gross, M. W.; Lee, M. A.; Lerche, I.

    1977-01-01

    Exact analytical solutions are presented for the standard time-independent spherically symmetric convection-diffusion-adiabatic deceleration equation governing the transport of cosmic rays in the interplanetary medium for the case in which particles are produced with spherical symmetry at the sun. It is assumed that the solar-wind speed is constant and radial, and that the spatial diffusion coefficient has a power-law dependence on momentum. The Green's function describing the modulation of a monoenergetic production of particles is presented. The solutions provide a useful basis for the study of time-integrated properties of energetic solar-flare particle spectra.

  9. Transport theory for energetic alpha particles in finite aspect ratio tokamaks with broken symmetry

    NASA Astrophysics Data System (ADS)

    Shaing, K. C.; Schlutt, M.; Lai, A. L.

    2016-02-01

    Transport theory for the energetic alpha particles in finite aspect ratio tokamaks with broken symmetry is developed for the case where the slowing down collision operator dominates. The transport fluxes in the 1 /ν and superbanana plateau regimes are derived. Here, ν is the typical collision frequency. They can be used in modeling the energy loss of the alpha particles in thermonuclear fusion reactors. Numerical realizations of the superbanana orbits of alpha particles in tokamaks with broken symmetry are also presented. The existence of the superbananas corroborates the predictions of the theories presented here and elsewhere.

  10. Fragmentation Energetics of Clusters Relevant to Atmospheric New Particle Formation

    SciTech Connect

    Bzdek, Bryan R.; Depalma, Joseph W.; Ridge, Douglas P.; Laskin, Julia; Johnston, Murray V.

    2013-02-27

    The exact mechanisms by which small clusters form and grow in the atmosphere are poorly understood, but this process may significantly impact cloud condensation nuclei number concentrations and global climate. Sulfuric acid is the key chemical component to new particle formation, but basic species such as ammonia are also important. However, few laboratory experiments address the kinetics or thermodynamics of acid and base incorporation into small clusters. This work utilizes a Fourier transform ion cyclotron resonance mass spectrometer equipped with surface-induced dissociation (FTICR-SID) to investigate time- and collision energy-resolved fragmentation of positively charged ammonium bisulfate clusters. Critical energies for dissociation are obtained from Rice-Ramsperger-Kassel-Marcus/Quasi-Equilibrium Theory (RRKM/QET) modeling of the experimental data and are compared to quantum chemical calculations of the thermodynamics of cluster dissociation. Fragmentation of ammonium bisulfate clusters occurs by two pathways: 1) a two-step pathway whereby the cluster sequentially loses ammonia followed by sulfuric acid and 2) a one-step pathway whereby the cluster loses an ammonium bisulfate molecule. Experimental critical energies for loss of an ammonia molecule and loss of an ammonium bisulfate molecule are higher than the thermodynamic values. If cluster growth is considered the reverse of cluster fragmentation, these results require the presence of an activation barrier to describe the incorporation of ammonia into small acidic clusters and suggest that kinetically (i.e. diffusion) limited growth should not be assumed. An important corollary is that models of atmospheric NPF should be revised to consider activation barriers to individual chemical steps along the growth pathway.

  11. The effect of momentum transfer by fast particles on the hydrodynamic instabilities in the ICF targets

    SciTech Connect

    Lykov, V.A.

    1994-10-05

    The results of the investigation into the hydrodynamic instabilities of media movement with the account of particle momentum transfer in ICF targets will be presented. It is shown that both oscillating and exponentially growing solutions for perturbation amplitude may exist depending on the ratio of particle free-path length and perturbation wavelength. The conditions of suppression of the Rayleigh-Taylor and Kelvin-Helmgoltz instabilities by particle momentum fluxes are obtained. The stabilization occurs due to the interaction of aperiodic modes of these instabilities with oscillation mode caused by the tensor anisothropy of particle momentum flux density. The possibility for essential effect of momentum transfer by {alpha}-particles from {ital D}{minus}{ital T} reaction on the development of the hydrodynamic instabilities during the phase of intensive ICF target burn is shown. {copyright} 1994 {ital American} {ital Institute} {ital of} {ital Physics}

  12. Quantitative study of the trapped particle bunching instability in Langmuir waves

    SciTech Connect

    Hara, Kentaro Boyd, Iain D.; Chapman, Thomas; Joseph, Ilon; Berger, Richard L.; Banks, Jeffrey W.; Brunner, Stephan

    2015-02-15

    The bunching instability of particles trapped in Langmuir waves is studied using Vlasov simulations. A measure of particle bunching is defined and used to extract the growth rate from numerical simulations, which are compared with theory [Dodin et al., Phys. Rev. Lett. 110, 215006 (2013)]. In addition, the general theory of trapped particle instability in 1D is revisited and a more accurate description of the dispersion relation is obtained. Excellent agreement between numerical and theoretical predictions of growth rates of the bunching instability is shown over a range of parameters.

  13. Effect of Coherent Structures on Energetic Particle Intensity in the Solar Wind at 1 AU

    NASA Astrophysics Data System (ADS)

    Tessein, J.; Ruffolo, D. J.; Wan, M.; Matthaeus, W. H.; Neugebauer, M.; Giacalone, J.

    2014-12-01

    We present results from an analysis of ACE observations of energeticparticles in the 0.047-4.75 MeV range associated with shocks and discontinuities in the solar wind. Inour previous work, Tessein et al. 2013, we found a high correlation between discontinuities, identified using the PVI statistic (essentially a normalized vectorincrement) and the intensity of energetic particles measured by ACE/EPAM. Our previous study was primarily a superposed epoch analysis using 12 years worth of data. In this study we look more closely at what causesthis correlation by examining individual events to determine whatcauses the association between the intensity and the location of the discontinuity. We find that in many cases the discontinuity is located at the rising or trailingedge of an energetic particle peak which revealsthat the discontinuities may act as barriers which inhibit the motion ofenergetic particles across the boundaries, rather than as sources of particleacceleration. We also find that the energetic particle peak is often associatedwith strong interplanetary shocks that are not documented in the ACE shocklist. The distinction between weak shocks and other discontinuities, which can appearsimilar in the observations, is a further complication that we address in this study.

  14. Overview of energetic particle hazards during prospective manned missions to Mars

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, Susan; Gonçalves, P.; Keating, A.; Reitz, G.; Matthiä, D.

    2012-04-01

    A scenario for an initial manned mission to Mars involves transits through the Van Allen Radiation Belts, a 30 day 'short surface stay' and a 400 day Cruise Phase (to/from the planet). The contribution to the total dose incurred through transiting the belts is relatively small and manageable. Estimates of the particle radiation hazard incurred during a 30 day stay on the surface (using ESA's Mars Energetic Radiation Environment Models dMEREM and e MEREM) indicate that the dose is not expected to be particularly challenging health-wise due to the shielding effect provided by the Martian atmosphere and the body of the planet. This is in accord with estimations obtained using the Langley HZETRN code. Estimates of GCR exposure in free space during the minimum phase of Solar Cycle 23 determined using the CREME2009 model are in reasonable agreement with published results obtained using HZETRN (which they exceed by about 10%). The Cruise Phase poses a significant radiation problem due to the cumulative effects of isotropic Galactic Cosmic Radiation over 400 days. The occurrence during this period of a large Solar Energetic Particle (SEP) event, especially if it has a hard energy spectrum, could be catastrophic health wise to the crew. Such particle events are rare but they are not currently predictable. An overview of mitigating strategies currently under development to meet the radiation challenge is provided and it is shown that the health problem posed by energetic particle radiation is presently unresolved.

  15. Pitch Angle Scattering of Energetic Particles by Waves Generated from a Rotating Magnetic Field Source

    NASA Astrophysics Data System (ADS)

    Shao, X.; Karavaev, A. V.; Sharma, A. S.; Papadopoulos, K.; Gumerov, N.; Gigliotti, A. F.; Gekelman, W. N.

    2009-12-01

    Injection of whistler waves into Earth's inner radiation belt to enhance precipitation of energetic electrons has been an active research area, and is referred to as RB Remediation (RBR). Most mechanisms of pitch angle scattering of energetic particles are based on gyro-resonant wave-particle interaction. Recent experiments and simulations show that Rotating Magnetic Field (RMF) antennas in plasmas can be efficient radiation sources of MHD and whistler waves. In experiments conducted in the Large Plasma Device (LAPD) at UCLA, poly-phased current loops drove the RMF antenna. These experiments, as well as simulations show that 75-85% of the radiation generated by the RMF antenna is in guided propagation. The whistler and MHD waves have non-local magnetic field gradients in the transverse direction and these provide ways to break the adiabatic invariants of electrons and precipitate them via a non-resonant scattering. In this paper simulations of non-resonant pitch angle scattering of energetic particles by waves generated by RMF sources are presented. Three-dimensional EMHD simulations are used to model whistlers and the resultant 3D electromagnetic fields are used in particle tracing codes to study pitch angle scattering. The simulations are carried out for a wide range of magnetic fields produced by RMF sources, including fields much larger than the ambient magnetic field in space plasma environments. This work was sponsored by ONR MURI Grant 5-28828

  16. Effects of Polar Cap Absorption of Energetic Particles on December 2006

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. V.; Yeh, H. C.; Tsai, L. C.

    2009-05-01

    Ionization effects produced at the northern polar ionosphere and upper atmosphere by energetic particles during December 2006 were studied. That period was accompanied by several solar flares and solar energetic particle (SEP) events as well as by several weak and one strong magnetic storms. Fluxes and spectra of energetic protons and electrons precipitating to the high-latitude and polar regions were measured by a constellation of four POES satellites at low-altitude orbit. The precipitating particles of solar, interplanetary and magnetospheric origin demonstrate different spectral properties and spatial distributions that permit us to study their dynamics separately. Magnetospheric particles are electrons having soft spectra and precipitating predominantly at auroral ionosphere. SEP together with particles accelerated at leading edge of interplanetary transients are characterized by higher energies and harder spectra. They penetrate to the magnetosphere in the polar cap region and causing abundant ionization of the lower ionosphere and upper atmosphere. Using POES data and standard models of the ionosphere and atmosphere we calculated height profiles of specific ionization produced by the SEP in the polar cap. The dynamics of SEP ionization reveals three intensifications at heights from 50 to 100 km in 7 to 8, 13 and 14 December. At the same time the ionization was measured as electron content (EC) by the COSMIC/FORMOSAT-3 constellation of six satellites. That experiment provides a 3- D tomography of the ionosphere and upper atmosphere on the base of radio occultation technique, which makes use of radio signals transmitted by the GPS satellites. We found that the observed temporal and spatial patterns of EC are pretty close to the dynamics of specific ionization, produced by the SEP and in particular by the electrons. Namely, the spatial region of enhanced ionization is overlapped pretty well with the enhancements of the electrons penetrating to the bottom

  17. PAH bombardment by energetic particles: models and astrophysical implications

    NASA Astrophysics Data System (ADS)

    Micelotta, E.; Jones, A.; Tielens, A.

    2011-05-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of the Interstellar Medium (ISM) of galaxies. Interstellar PAHs are apparently able to withstand the rigors of the harsh environment of the ISM for some some 100 million years and thus are resilient against processing by UV and X-ray photons and supernova shock waves. PAHs in space are mainly studied through their characteristic emission bands, due to infrared fluorescence following the absorption of UV photons. This is the reason why the photophysics of PAHs in space has been extensively investigated. On the other hand, PAHs are also strongly affected by collisional processes, i.e. bombardment by high-velocity ions and electrons, arising from interstellar shocks, hot gas and cosmic rays. However, very little was known about the physics of the interaction between PAHs and high energy particles, especially in terms of PAH damage and destruction. This lack of information had made the interpretation of PAH observations difficult in regions subjected to such processes. Our research aims to fill this key gap in our understanding of the physics behind collisional processing of PAHs and to clarify how this affects the PAH evolution in the astrophysical context. We first describe the models we have developed, that take into account the molecular nature of the target PAH and allow for the first time a quantitative description of the collisional processing of PAH molecules by ions and electrons with energies between 10 eV and 10 keV (in shocks and hot gas) and between 5 MeV and 10 GeV (in cosmic rays). Specific models were needed because PAHs are molecules and not small solid fragments, thus the classical approach from solid state physics cannot be applied. We then show the applications of our models to observations, estimating the lifetime of PAHs against collisional processing in specific objects. We discuss the astrophysical implications of our findings on the considered sample, which

  18. OBSERVATIONAL EVIDENCE ON THE PRESENCE OF AN OUTER REFLECTING BOUNDARY IN SOLAR ENERGETIC PARTICLE EVENTS

    SciTech Connect

    Tan, Lun C.; Reames, Donald V.; Ng, Chee K.; Saloniemi, Oskari; Wang Linghua

    2009-08-20

    We have focused primarily on the 2001 September 24 solar energetic particle (SEP) event to verify previous indications of the presence of an outer reflecting boundary of SEPs. By using energetic electron and ion data obtained from multi-spacecraft observations, we have identified a collimated particle beam consisting of reflected particles returning from an outer boundary. The peak of reflected particles appears before the arrival of particles at 90 deg. pitch angle. In addition, an onset time analysis is carried out in order to determine parameters characterizing the boundary. Our analysis suggests that the presence of a counter-streaming particle beam with a deep depression at {approx}90 deg. pitch angle during the onset phase is evidence for a nearby reflecting boundary. We have compared this property in the SEP events of 2002 April 21 and August 24. A reflecting boundary that blocks a flux tube is important in space weather forecasting since it can cause the 'reservoir' effect that may enhance the intensity and duration of high-energy particles.

  19. Energetic particles and coronal mass ejections in the high latitude heliosphere: Ulysses-LET observations

    NASA Technical Reports Server (NTRS)

    Bothmer, V.; Sanderson, T. R.; Marsden, R. G.; Wenzel, K.-P.; Goldstein, B. E.; Balogh, A.; Forsyth, R. J.; Uchida, Y.

    1995-01-01

    The COSPIN Low Energy Telescope (LET) onboard the Ulysses spacecraft measures protons, alphas and heavier ions at energies of approximately 1 to 50 MeV/n. Ulysses measurements offer favorable opportunities to study the effects of solar activity in the out-of-ecliptic regions of the heliosphere. Using LET data, we have investigated the properties of transient energetic ions at high heliographic latitudes when Ulysses was permanently immersed in high speed solar wind and magnetically connected to the Sun on open magnetic field lines. Recurrent increases in the fluxes of energetic ions at high heliographic latitudes at frequencies related to the solar rotation period were found to occur in association with co-rotating interaction regions (CIRs). Here we investigate fluxes of energetic particles that showed no relationship to ClRs. From the investigation of plasma and magnetic held data it is found that all of the transient high latitude particle events were associated with the passage of a coronal mass ejection (CME) over Ulysses. Enhancements in particle fluxes several days prior to the arrival of a CME, but with a significant time delay with respect to the estimated CME-onset at the Sun, were most probably associated with interplanetary shocks driven by fast CMEs. These particle events exhibit unusually high rho/alpha-ratios and are not observed for CMEs not driving a shock. However, not all CMEs that passed Ulysses were associated with a particle event. We find evidence that at high solar latitudes, solar flare particles cannot reach Ulysses on open magnetic field lines, but can reach the spacecraft if particles are injected into magnetic flux-ropes (CMEs) at the Sun. These findings are supported by soft X-ray observations from the Japanese Yohkoh-satellite.

  20. Manned Mars mission solar physics: Solar energetic particle prediction and warning

    NASA Technical Reports Server (NTRS)

    Suess, S. T.

    1986-01-01

    There are specific risks to the crew of the manned Mars mission from energetic particles generated by solar activity. Therefore, mission planning must provide for solar monitoring and solar activity forecasts. The main need is to be able to anticipate the energetic particle events associated with some solar flares and, occasionally, with erupting filaments. A second need may be for forecasts of solar interference with radio communication between the manned Mars mission (during any of its three phases) and Earth. These two tasks are compatible with a small solar observatory that would be used during the transit and orbital phases of the mission. Images of the Sun would be made several times per hour and, together with a solar X-ray detector, used to monitor for the occurrence of solar activity. The data would also provide a basis for research studies of the interplanetary medium utilizing observations covering more of the surface of the Sun than just the portion facing Earth.

  1. Energetic particles and waves in the Jupiter's and Saturn's radiation belts

    NASA Astrophysics Data System (ADS)

    Krupp, Norbert; Roussos, Elias; Paranicas, Chris; Sicard, Angelica; Hospodarsky, George; Shprits, Yuri

    2016-04-01

    The radiation belts of Jupiter and Saturn are among the harshest environments in our solar system. In extremely strong internal closed magnetic field configurations energetic particles up to several hundred MeV energies are trapped and bounce back and forth along the magnetic field lines emitting waves in a whole variety of frequencies. Charged particle drift paths in the rotationally-dominated magnetospheres close around the whole planet to substantial planetary distances, unlike in the case of Earth. The combination of a strong internal magnetic field and quasi-stable trapping allows the fluxes of energetic ions and electrons to become very large. In this presentation the available in-situ measurements of Jupiter's and Saturn's radiation belts are reviewed as well as current modelling approaches. In addition some aspects of the expected measurements of the Jovian radiation belts from the upcoming JUNO mission will be discussed.

  2. Detection of lower tropospheric responses to solar energetic particles at midlatitudes.

    PubMed

    Nicoll, K A; Harrison, R G

    2014-06-01

    Solar energetic particles (SEPs) occasionally contribute additional atmospheric ionization beyond that arising from the usual galactic cosmic ray background. During an SEP event associated with a solar flare on April 11, 2013, the vertical ionization rate profile obtained using a balloon-borne detector showed enhanced ionization with a 26% increase at 20 km, over Reading, United Kingdom. Fluctuations in atmospheric electrical parameters were also detected at the surface, beneath the balloon's trajectory. As no coincident changes in geomagnetism occurred, the electrical fluctuations are very likely to be associated with increased ionization, as observed by the balloon measurements. The lack of response of surface neutron monitors during this event indicates that energetic particles that are not detected at the surface by neutron monitors can nevertheless enter and influence the atmosphere's weather-generating regions. PMID:24949773

  3. Observations of interplanetary energetic charged particles from gamma-ray line solar flares

    NASA Technical Reports Server (NTRS)

    Pesses, M. E.; Gloeckler, G.; Klecker, B.; Hovestadt, D.

    1981-01-01

    Results from ISEE-3 experiments on interplanetary energetic charged particles on June 7, June 21, and July 1, 1980 dealing with gamma ray producing solar flares are reported. The data were gathered by the Ultra Low Energy Wide Angle Telescope, which comprises a thin window, flow through proportional counter/solid-state detector composition telescope. Evidence of a specified time delay from an observed flare and the recording of 0.44-1.3 MeV electrons on ISEE-3 combined with quiescent periods of at least two hours before the observations and recording provides a link between the events. The data indicates interplanetary energetic particle enhancement, and a second, similar set of occurrences was also observed. Protons were accelerated up to 10-20 MeV. No enrichment of either He-3 or Fe was found.

  4. Type II solar radio bursts, interplanetary shocks, and energetic particle events

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Stone, R. G.

    1984-01-01

    Using the ISEE-3 radio astronomy experiment data 37 interplanetary (IP) type II bursts have been identified in the period September 1978 to December 1981. These events and the associated phenomena are listed. The events are preceded by intense, soft X ray events with long decay times (LDEs) and type II and/or type IV bursts at meter wavelengths. The meter wavelength type II bursts are usually intense and exhibit herringbone structure. The extension of the herringbone structure into the kilometer wavelength range results in the occurrence of a shock accelerated (SA) event. The majority of the interplanetary type II bursts are associated with energetic particle events. These results support other studies awhich indicate that energetic solar particles detected at 1 A.U. are generated by shock acceleration. From a preliminary analysis of the available data there appears to be a high correlation with white light coronal transients.

  5. Energetic particle observations and the abundances of elements in the solar corona

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1992-01-01

    During the last few years it has become clear that energetic particles in the largest solar events, where abundances are commonly measured, are not accelerated in flares. Rather they are accelerated from the ambient plasma above active regions by shock waves driven by coronal mass ejections. The lowest energy particles from these events have abundances that almost directly reflect those of the source plasma. Residual effects of acceleration, that depend smoothly on the ion's corona Q/A, vanish when abundances are averaged over many events, yielding the characteristic dependence of the average coronal abundances of the First Ionization Potential (FIP) of the elements from H through Fe. In contrast, energetic ions accelerated out of the high speed solar wind from large coronal holes show a reduced FIP effect with a different pattern.

  6. Bulk Flow Velocity and First-Order Anisotropy of Solar Energetic Particles Observed on Wind Spacecraft

    NASA Astrophysics Data System (ADS)

    Tan, L. C.; Reames, D. V.; Ng, C. K.

    2006-12-01

    We have developed a technique to calculate the bulk flow velocity and first-order anisotropy of solar energetic particles (SEPs) with MeV per nucleon energies. Using the technique we have selected and analyzed three "gradual" SEP events recorded by the Low-Energy Matrix Telescope (LEMT) of the Energetic Particles: Acceleration, Composition, and Transport experiment (EPACT) on the Wind spacecraft. Since in our selected events, the interplanetary magnetic field upstream of interplanetary (IP) shock is nearly perpendicular to the solar-wind velocity, the effect of SEP scattering centers can be clearly discerned. From the observations of H, He, O, and Fe ions at different energies, we find that upstream of IP shock the bulk flow direction of heavy ions is opposite to that of protons. In addition, the ion velocity/rigidity dependence of the first-order anisotropy of SEPs is different between the onset and the upstream region. The implication of our observations will be discussed.

  7. A rocket-borne electrostatic analyzer for measurement of energetic particle flux

    NASA Technical Reports Server (NTRS)

    Pozzi, M. A.; Smith, L. G.; Voss, H. D.

    1979-01-01

    A rocket-borne electrostatic analyzer experiment is described. It is used to measure energetic particle flux (0.9 to 14 keV) in the nighttime midlatitude E region. Energetic particle precipitation is believed to be a significant nighttime ionization source, particularly during times of high geomagnetic activity. The experiment was designed for use in the payload of a Nike Apache sounding rocket. The electrostatic analyzer employs two cylindrical parallel plates subtending a central angle of 90 deg. The voltage waveform supplied to the plates is a series of steps synchronized to the spin of the payload during flight. Both positive and negative voltages are provided, extending the detection capabilities of the instrument to both electrons and protons (and positive ions). The development, construction and operation of the instrument is described together with a preliminary evaluation of its performance in a rocket flight.

  8. Solar energetic particles as probes of the structures of magnetic clouds

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Reames, D. V.

    Two possible closed magnetic topologies are considered for clouds: an elongated bottle with field lines rooted at both ends in the sun and a magnetic bubble or plasmoid consisting of closed field lines. Solar energetic particles (SEPs) are used as probes of the cloud topologies. The rapid access of SEPs to clouds in many events indicates that the cloud field lines extend back to the sun.

  9. Diagnostics for energetic particle studies on the HL-2A tokamak

    SciTech Connect

    Yang, Q. W. Zhou, H. Y.; Yang, J. W.; Shi, Z. B.; Ji, X. Q.; Yuan, G. L.; Zhang, Y. P.; Yu, D. L.; Jiang, M.; Li, W.; Ding, X. T.; Yin, Z. J.; Cao, H. R.

    2014-11-15

    About 13 kinds of diagnostics for energetic particle physics studied on the HuanLiuqi-2A (commonly referred to as HL-2A) tokamak are described in this paper. Their measurement ranges, resolutions, and arrangement are presented. Three under-construction diagnostics including imaging fast ion D-alpha, scintillator matrix (for hard X-ray detection), and bundle fission chamber are described in detail.

  10. Solar energetic particle events and coronal mass ejections: New insights from SOHO

    NASA Technical Reports Server (NTRS)

    Bothmer, V.; Posner, A.; Kunow, H.; Mueller-Mellin, R.; Heber, B.; Pick, M.; Thompson, B. J.; Delaboudiniere, J.-P.; Brueckner, G. E.; Howard, R. A.; Michels, D. J.; St.Cyr, C.; Szabo, A.; Hudson, H. S.; Mann, G.; Classen, H.-T.; McKenna-Lawlor, S.

    1997-01-01

    The scientific payload of SOHO, launched in December 1995, enables comprehensive studies of the sun from its interior, to the outer corona and solar wind. In its halo orbit around the Lagrangian point of the sun-earth system, the comprehensive suprathermal and energetic particle analyzer (COSTEP) measures in situ energetic partiles in the energy range 44 keV/particle to greater than 53 MeV/n. Although solar activity was at minimum, COSTEP detected from mid December 1995 until the end of July 1997, 30 solar energetic particle (SEP) events, including both gradual and implusive type SEPs. These minimum phase SEP events are unique in the sense that their associated solar source phenomena can be investigated in detail without interference by other simultaneous solar events as is usually the case at times around solar activity maximum. Simultaneous observations of the solar corona are provided by the large angle spectroscopic coronagraph (LASCO) and the extreme ultraviolet imaging telescope (EIT). From the correlated SOHO observations, a one to one correspondence of SEP events with coronal mass ejections (CMEs) was found. Most of the SEP events were associated with west-limb CMEs, some with halo CMEs that later passed the SOHO spacecraft and with Moreton-like disturbances in the lower solar atmosphere as observed by the EIT. Many SEP events were detected at sector boundaries of the interplanetary magnetic field (IMF) suggesting a magnetic connection to coronal streamers at the sun as supported by LASCO observations of mass ejections at the base of helmet streamers. Energetic particle and LASCO white-light observations yield evidence that CMEs often lead to large-scale disturbances of the sun's corona, probably affecting at times areas all around the sun.

  11. Convective and Diffusive Energetic Particle Losses Induced by Shear Alfven Waves in the ASDEX Upgrade Tokamak

    SciTech Connect

    Garcia-Munoz, M.; Hicks, N.; Bilato, R.; Bobkov, V.; Bruedgam, M.; Fahrbach, H.-U.; Igochine, V.; Maraschek, M.; Sassenberg, K.; Voornveld, R. van; Classen, I. G. J.; Jaemsae, S.

    2010-05-07

    We present here the first phase-space characterization of convective and diffusive energetic particle losses induced by shear Alfven waves in a magnetically confined fusion plasma. While single toroidal Alfven eigenmodes (TAE) and Alfven cascades (AC) eject resonant fast ions in a convective process, an overlapping of AC and TAE spatial structures leads to a large fast-ion diffusion and loss. Diffusive fast-ion losses have been observed with a single TAE above a certain threshold in the fluctuation amplitude.

  12. Geosynchronous Energetic Particle (EP) Data Plots from Los Alamos National Laboratory (LANL)

    DOE Data Explorer

    Belian, Dick; Reeves, Geoff; Dors, Eric

    LANL's Geosynchronous Energetic Particle activities include collecting and analyzing data from ten satellites in an ongoing program sponsored by DOE.  Data acquisition has been continuous since 1976 and is received in real time 24 hours a day.  The website provides access to Low Energy proton and electron summary plots, showing spin-averaged fluxes from each satellite for each day since July 4, 1976.

  13. Fe embedded in ice: The impacts of sublimation and energetic particle bombardment

    NASA Astrophysics Data System (ADS)

    Frankland, Victoria L.; Plane, John M. C.

    2015-05-01

    Icy particles containing a variety of Fe compounds are present in the upper atmospheres of planets such as the Earth and Saturn. In order to explore the role of ice sublimation and energetic ion bombardment in releasing Fe species into the gas phase, Fe-dosed ice films were prepared under UHV conditions in the laboratory. Temperature-programmed desorption studies of Fe/H2O films revealed that no Fe atoms or Fe-containing species co-desorbed along with the H2O molecules. This implies that when noctilucent ice cloud particles sublimate in the terrestrial mesosphere, the metallic species embedded in them will coalesce to form residual particles. Sputtering of the Fe-ice films by energetic Ar+ ions was shown to be an efficient mechanism for releasing Fe into the gas phase, with a yield of 0.08 (Ar+ energy=600 eV). Extrapolating with a semi-empirical sputtering model to the conditions of a proton aurora indicates that sputtering by energetic protons (>100 keV) should also be efficient. However, the proton flux in even an intense aurora will be too low for the resulting injection of Fe species into the gas phase to compete with that from meteoric ablation. In contrast, sputtering of the icy particles in the main rings of Saturn by energetic O+ ions may be the source of recently observed Fe+ in the Saturnian magnetosphere. Electron sputtering (9.5 keV) produced no detectable Fe atoms or Fe-containing species. Finally, it was observed that Fe(OH)2 was produced when Fe was dosed onto an ice film at 140 K (but not at 95 K). Electronic structure theory shows that the reaction which forms this hydroxide from adsorbed Fe has a large barrier of about 0.7 eV, from which we conclude that the reaction requires both translationally hot Fe atoms and mobile H2O molecules on the ice surface.

  14. Solar energetic particles as probes of the structures of magnetic clouds

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.; Reames, D. V.

    1990-01-01

    Two possible closed magnetic topologies are considered for clouds: an elongated bottle with field lines rooted at both ends in the sun and a magnetic bubble or plasmoid consisting of closed field lines. Solar energetic particles (SEPs) are used as probes of the cloud topologies. The rapid access of SEPs to clouds in many events indicates that the cloud field lines extend back to the sun.

  15. Local and global scattering properties of the interplanetary medium obtained from Solar Energetic Particles (SEPs)

    NASA Technical Reports Server (NTRS)

    Wibberenz, G.; Hatzky, R.; Bieber, J. W.

    1995-01-01

    Solar energetic particles can be used as probes for the turbulence level in the interplanetary medium. It is of general interest to compare the LOCAL scattering properties near an observer with GLOBAL properties which characterize the average scattering along the magnetic field. We discuss various methods by which the scattering conditions can be determined: (1) overall fits of observed particle intensities and anisotropies to a transport model; (2) evaluation of the steady-state pitch angle distribution; and (3) suitably normalized angular distributions during the intensity maximum of a particle event. Energetic particle data from HELIOS 1/2 are analyzed, and the mean free paths obtained with the different methods are compared with each other. As a result one can state: (1) for a number of solar particle events the radial mean free path is essentially constant between the Sun and Helios; and (2) large variations in the degree of scattering exist from one event to the other. These results indicate the existence of 'regimes' where the amount of particle scattering is relatively constant over extended regions in radius and azimuth, but with marked differences from one regime to the other.

  16. Downstream energetic proton and alpha particles during quasi-parallel interplanetary shock events

    NASA Technical Reports Server (NTRS)

    Tan, L. C.; Mason, G. M.; Gloeckler, G.; Ipavich, F. M.

    1988-01-01

    This paper considers the energetic particle populations in the downstream region of three quasi-parallel interplanetary shock events, which was explored using the ISEE 3 Ultra Low Energy Charge Analyzer sensor, which unambiguously identifies protons and alpha particles using the electrostatic deflection versus residual energy technique. The downstream particles were found to exhibit anisotropies due largely to convection in the solar wind. The spectral indices of the proton and the alpha-particle distribution functions were found to be remarkably constant during the downstream period, being generally insensitive to changes in particle flux levels, magnetic field direction, and solar wind densities. In two of the three events, the proton and the alpha spectra were the same throughout the entire downstream period, supporting the prediction of diffusive shock acceleration theory.

  17. Neutralized solar energetic particles in the inner heliosphere: a parameter study

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Dong; Klecker, Berndt; Futaana, Yoshifumi; Cipriani, Fabrice; Barabash, Stas; Wieser, Martin

    2016-04-01

    The large fluxes of solar energetic particles (SEPs) in Gradual Events, dominated by protons, are believed to be produced by the acceleration of shocks driven by coronal mass ejections (CMEs). As SEPs propagate in the lower corona, there is a chance for them to be neutralized via the charge exchange and/or recombination processes and become energetic neutral atoms (ENAs). These ENAs retain the velocity of their parent SEPs and propagate in straight lines without the influence of the interplanetary magnetic field, and therefore might potentially serve as a new window to observe the particle acceleration processes in the solar corona. STEREO/Low Energy Telescope reported the first probable observation of hydrogen ENAs between 1.6 MeV - 5 MeV from the Sun prior to an X-class flare/CME [Mewaldt et al., 2009]. While such observations were somehow controversial, Wang et al. [2014] simulated the neutralization of solar energetic protons in the corona lower than 40 RS, and the result agreed with the STEREO observation. In this work, we further developed a production model of the ENA near the sun together with a transport model toward the inner planets, and explore the dependences of the ENA characteristics against the model parameters. These parameters include the angular width of the CME, its propagation direction with respect to the Sun-observer line, the propagation speed, the particle density in the corona, the abundances of O6+ and C4+, and the reaction rate of electron impact ionization in the loss of ENAs, and the heliospheric distance of the observer. The calculated ENA flux shows that at lower energy the expected ENA flux depends most sensitively on the CME apex angle and the CME propagation direction. At higher energy the dependence on the coronal density is more prominent. References Mewaldt, R. A., R. A. Leske, E. C. Stone, A. F. Barghouty, A. W. Labrador, C. M. S. Cohen, A. C. Cummings, A. J. Davis, T. T. von Rosenvinge, and M. E. Wiedenbeck (2009), STEREO

  18. Instabilities excited by an energetic ion beam and electron temperature anisotropy in tandem mirrors

    NASA Technical Reports Server (NTRS)

    Da Jornada, E. H.; Gaffey, J. D., Jr.; Winske, D.

    1985-01-01

    Tandem mirrors are magnetic confinement devices, which have the objective to prevent a leaking out of ions in a central (solenoidal) cell at the end. This is accomplished by making use of an electrostatic potential, which is maintained by a denser plasma in mirror end cells. In the Tandem Mirror Experiment (TMX), Correll et al. (1982) have successfully verified the basic concepts involved in the design of the considered device. However, it was also found that the simple tandem mirror could not be easily scaled to a reactor-size device. Approaches for solving the arising problems were studied, taking into account also the utilization of a thermal barrier. In this connection, Winske et al. (1985) studied the nonlinear development of the instability in a finite beta plasma with isotropic electrons. The present investigation is concerned with an extension of the calculations conducted by Winske et al., giving attention to the parameter regime of the TMX. It is found that three instabilities can occur.

  19. Investigating the Causes of Solar-Cycle Variations in Solar Energetic Particle Fluences and Composition

    NASA Astrophysics Data System (ADS)

    Mewaldt, Richard; Cohen, Christina; Mason, Glenn M.; von Rosenvinge, Tycho; Li, Gang; Smith, Charles; Vourlidas, Angelos

    2015-04-01

    Measurements with ACE, STEREO, and GOES show that the number of large Solar Energetic Particle (SEP) events in solar cycle 24 is reduced by a factor of ~2 compared to this point of cycle 23, while the fluences of >10 MeV/nuc ions from H to Fe are reduced by factors ranging from ~4 to ~10. We investigate the origin of these cycle-to-cycle differences by evaluating possible factors that include properties of the associated CMEs, seed particle densities, and the interplanetary magnetic field strength and turbulence levels. These properties will be evaluated in the context of existing SEP acceleration models.

  20. Interplanetary challenge of monitoring energetic solar particles by university satellite UNITEC-1

    NASA Astrophysics Data System (ADS)

    Yamamoto, Masa-Yuki; Takashima, Takeshi; Kimura, Shinichi; Nakasuka, Shinichi

    As a piggy-back satellite of Planet-C, the first Japanese Venus explorer, a small-size univer-sity satellite UNITEC-1 was manufactured by 22 participanting Universities and Institutes of National College of Technology in Japan, members of the UNISEC (UNIversity Space Engi-neering Consortium), expecting to be injected to Hohmann orbit to the Venus by H-IIA vehicle. Testing of deep space communication from small-size satellite (30 cm cube) as well as a sur-vival competition of on-board 6 student-made circuits with using commercial-use computers are planned for missions of the UNITEC-1. There would be the world first university satellite to the interplanetary space. In order to obtain any scientific results from the small testing satellite of UNITEC-1, we installed SPM (Solar Particle Monitor), an energetic particle counter in a range up to a few GeV. Even in severe limitation of communication line from small-size satellite in deep space (limit at 6,000,000 km from the Earth, in expectation), based on optimum on-board processing in cases of expected solar events, we will monitor the energetic solar particles as far as possible. Energetic solar particles released from the sun by flares or CME (Coronal Mass Ejection) events can reach to the Earth orbit within 1 hour, being detected by, for example, GOES satellite on stationary orbit as charged particles (mainly protons) in a range between a few tens MeV and a few GeV. These particles are not only harmful for astronaut activities on orbit but also affective on malfunctions of satellites. Monitoring such particles at any other point on interplanetary space is significant for the flare/CME studies because opportunities of interplanetary cruise are very limited. Previously, SPM on-board NOZOMI, Japanese Mars explorer monitored the solar energetic particles during 1998-2004. In this paper, observation plan (and hopufully the first data on orbit) by the UNITEC-1/SPM and its development process will be shown as space

  1. OT2_cceccare_4: Searching for the onset of energetic particle irradiation in Class 0 protostars

    NASA Astrophysics Data System (ADS)

    Ceccarelli, C.

    2011-09-01

    Several evidences tell us that the first stages of low mass star formation are very violent, characterized by, among other phenomena, an intense irradiation of energetic (MeV) particles. The goal of this proposal is to search for signs of MeV particle irradiation in a sample of low to intermediate mass Class 0 protostars. At this end, we propose to observe a selected list of high J HCO+ and N2H+ lines in a selected sample of sources. Based on the observations obtained within the KP CHESS, we estimate a total observing time of 20.5 hours.

  2. The importance of energetic particle precipitation on the chemical composition of the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Thorne, R. M.

    1980-01-01

    The present review deals with the importance of three distinct classes of precipitation which directly deposit energy into the middle atmosphere, viz. galactic cosmic radiation, energetic solar protons and relativistic electron precipitation from the earth's radiation belts. Chemical considerations during particle precipitation are discussed, with special emphasis on the relative production rate of odd nitrogen and odd hydrogen species during ionizing particle precipitation. The long residence time of NO in the upper stratosphere, where catalytic interaction with O3 is most effective, requires that this mechanism be included in future modeling of global distribution of O3. Other situations causing O3 depletion are also identified.

  3. Modeling Mission-Specific Worst-Case Solar Energetic Particle Reference Environments

    NASA Astrophysics Data System (ADS)

    Adams, James; Michael, Michael; Dietrich, William F.

    2012-07-01

    To plan and design safe and reliable space missions, it is necessary to take into account the effects of the space radiation environment. Solar energetic particle events can dramatically increase the intensity of the space radiation environment. The enhanced radiation levels during episodes of solar activity must be considered by spacecraft designers and mission planners. This is done by using a reference environment obtained from a solar particle model. Ongoing work will be presented on a model to provide mission specific reference environments at user-specified confidence levels.

  4. Nonlinear dynamics of beta-induced Alfvén eigenmode driven by energetic particles.

    PubMed

    Wang, X; Briguglio, S; Chen, L; Di Troia, C; Fogaccia, G; Vlad, G; Zonca, F

    2012-10-01

    Nonlinear saturation of a beta-induced Alfvén eigenmode, driven by slowing down energetic particles via transit resonance, is investigated by the nonlinear hybrid magnetohyrodynamic gyrokinetic code. Saturation is characterized by frequency chirping and symmetry breaking between co- and counter-passing particles, which can be understood as the evidence of resonance detuning. The scaling of the saturation amplitude with the growth rate is also demonstrated to be consistent with radial resonance detuning due to the radial nonuniformity and mode structure. PMID:23214643

  5. Global Hybrid Simulations of Energetic Particle-driven Modes in Toroidal Plasmas

    SciTech Connect

    G.Y. Fu; J. Breslau; E. Fredrickson; W. Park; H.R. Strauss

    2004-12-14

    Global hybrid simulations of energetic particle-driven MHD modes have been carried out for tokamaks and spherical tokamaks using the hybrid code M3D. The numerical results for the National Spherical Tokamak Experiments (NSTX) show that Toroidal Alfven Eigenmodes are excited by beam ions with their frequencies consistent with the experimental observations. Nonlinear simulations indicate that the n=2 mode frequency chirps down as the mode moves out radially. For ITER, it is shown that the alpha-particle effects are strongly stabilizing for internal kink mode when central safety factor q(0) is sufficiently close to unity. However, the elongation of ITER plasma shape reduces the stabilization significantly.

  6. Solar energetic particle track densities as an indicator of the origin of interplanetary dust

    NASA Technical Reports Server (NTRS)

    Blanford, George E.

    1994-01-01

    An examination of the relation of track densities from solar energetic particles in interplanetary dust grains (IDP's) to the orbital elements of source bodies is made and the positive and negative aspects of using track densities to determine the origin of IDP's are reported. It is found from calculations that predicted track densities for a particle of given size are related logarithmically to the minimum semimajor axis of the source body. Consequently, although track densities measurements may not be capable of distinguishing cometary from asteroidal sources, they should give information on the minimum semimajor axis of the originating bodies.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  8. Solar energetic particles inside magnetic clouds observed with the Wind spacecraft

    NASA Astrophysics Data System (ADS)

    Mazur, J. E.; Mason, G. M.; Dwyer, J. R.; von Rosenvinge, T. T.

    Solar energetic particles can be used to probe the structure of magnetic clouds. Since impulsive flare particles are accelerated within active regions, their presence inside a magnetic cloud implies that the cloud's magnetic field connects to an active region at the sun. We report on the fluxes and composition of low energy ions inside 13 magnetic clouds observed with instrumentation on the Wind spacecraft from November 1994 to February 1997. The STEP subsystem of the EPACT experiment on Wind resolves ³He and 4He and the most abundant heavy ion species from ∼20 keV/nucleon to ∼1 MeV/nucleon. Using STEP, we are able to measure the energetic particle composition in an energy range previously unexplored in the context of magnetic clouds. We find that when STEP measured significant ion fluxes inside a cloud, they were most likely from impulsive solar flares; this was the case in 4 events. We find that the 1/10/97 magnetic cloud decreased the interplanetary fluxes of ∼100 keV/nucleon ions by a factor of ∼10² this was probably because the cloud disconnected Wind from the interplanetary particle source beyond 1 AU. In contrast, we observed particles from several impulsive solar flares inside the 10/18/95 event with fluxes ∼10³ higher than the fluxes measured inside the 1/10/97 cloud.

  9. Solar Energetic Particle Event Associated with the 2012 July 23 Extreme Solar Storm

    NASA Astrophysics Data System (ADS)

    Zhu, Bei; Liu, Ying D.; Luhmann, Janet G.; Hu, Huidong; Wang, Rui; Yang, Zhongwei

    2016-08-01

    We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which Solar Terrestrial Relations Observatory (STEREO) and the spacecraft at L1 provide multi-point remote sensing and in situ observations. The extreme solar storm, with a superfast shock and extremely enhanced ejecta magnetic fields observed near 1 au at STEREO A, was caused by the combination of successive coronal mass ejections (CMEs). Meanwhile, energetic particles were observed by STEREO and near-Earth spacecraft such as the Advanced Composition Explorer and SOlar and Heliospheric Observatory, suggesting a wide longitudinal spread of the particles at 1 au. Combining the SEP observations with in situ plasma and magnetic field measurements, we investigate the longitudinal distribution of the SEP event in connection with the associated shock and CMEs. Our results underscore the complex magnetic configuration of the inner heliosphere formed by solar eruptions. Examination of particle intensities, proton anisotropy distributions, element abundance ratios, magnetic connectivity, and spectra also gives important clues for particle acceleration, transport, and distribution.

  10. Modeling the 2003 Halloween events with EMMREM: Energetic particles, radial gradients, and coupling to MHD

    NASA Astrophysics Data System (ADS)

    Kozarev, K.; Schwadron, N. A.; Dayeh, M. A.; Townsend, L. W.; Desai, M. I.; PourArsalan, M.

    2010-11-01

    The Earth-Moon-Mars Radiation Environment Module (EMMREM) is a comprehensive numerical framework for characterizing and predicting the radiation environment of the inner heliosphere. We present a study of the October/November 2003 Halloween solar energetic particle events with an energetic particle acceleration and propagation model that is part of EMMREM, highlighting the current ability of the framework to make predictions at various locations of the inner heliosphere. We compare model predictions with Ulysses observations of protons at energies above 10 MeV in order to obtain realistic proton fluxes and calculate radial gradients for peak fluxes, event fluences, and radiation dosimetric quantities. From our study, we find that a power law with an index of -3.55 at energy of 200 MeV describes the time-integrated energetic proton fluence dependence on radial distances beyond 1 AU for the 2003 Halloween events, and an index of -4.18 is appropriate for peak proton fluxes at that energy. Calculations of radiation doses based on these simulations show average power law indices of -4.32 and -3.64 for peak dose rates and accumulated doses, respectively. In an effort to improve the predictions, we have coupled our kinetic code to results from a 3-D heliospheric magnetohydrodynamic model, WSA/Enlil. While predictions with the coupled model overall show worse agreement than simulations with steady state solar wind conditions for these large events, the capability to couple energetic particle propagation and numerical models of the solar wind is an important step in the future development of space weather modeling.

  11. Perpendicular diffusion of energetic particles: Numerical test of the theorem on reduced dimensionality

    SciTech Connect

    Qin, G.; Shalchi, A.

    2015-01-15

    A fundamental statement in diffusion theory is provided by the so-called theorem on reduced dimensionality. The latter theorem is saying that if the dimensionality of the turbulence is reduced, charged particles are tied to a single magnetic field line. If there is pitch-angle scattering and therewith parallel diffusion, this usually means that perpendicular transport is subdiffusive. Subdiffusive transport was found in numerous simulations for slab turbulence. However, it was unclear whether the theorem is valid for other models with reduced dimensionality such as the two-dimensional model. In the current paper, we simultaneously trace magnetic field lines and energetic particles and we compute the distance between the particle and the initial field line. We confirm the aforementioned theorem for slab turbulence but we cannot confirm it for two-dimensional turbulence. We also show that particles are not tied to field lines for two-component turbulence.

  12. Focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection

    NASA Technical Reports Server (NTRS)

    Tan, L. C.; Mason, G. M.; Lee, M. A.; Klecker, B.; Ipavich, F. M.

    1992-01-01

    Evidence is presented for focused transport of energetic particles along magnetic field lines draped around a coronal mass ejection. This evidence was obtained with the University of Maryland/Max-Planck-Institute experiment on the ISEE-3 spacecraft during the decay phase of the June 6, 1979, solar particle event. During the early portion of the decay phase of this event, interplanetary magnetic field lines were apparently draped around a coronal mass ejection, leading to a small focusing length on the western flank where ISEE 3 was located. A period of very slow decrease of particle intensity was observed, along with large sunward anisotropy in the solar wind frame, which is inconsistent with predictions of the standard Fokker-Planck equation models for diffusive transport. It was found possible to fit the observations, assuming that focused transport dominates and that the particle pitch angle scattering is isotropic.

  13. NONRESONANT INTERACTION OF CHARGED ENERGETIC PARTICLES WITH LOW-FREQUENCY NONCOMPRESSIVE TURBULENCE: NUMERICAL SIMULATION

    SciTech Connect

    Ragot, B. R.

    2012-10-20

    A new method for simulating the three-dimensional dynamics of charged energetic particles in very broadband noncompressive magnetic turbulence is introduced. All scales within the primary inertial range of the turbulence observed in the solar wind near 1 AU are now included for the independent computations of both the particle dynamics and the turbulent magnetic field lines (MFLs). While previous theories of resonant particle pitch-angle (PA) scattering and transport in interplanetary magnetic fields had favored interpreting the observed depletions in the electron PA distributions (PADs) around 90 Degree-Sign PA as evidence of poor scattering at low PA cosines, the computed particle dynamics reveal a very different reality. The MFL directions now vary on many scales, and the PADs are depleted around 90 Degree-Sign PA due to nonresonant filtering of the particles that propagate at too large an angle to the local magnetic field. Rather than being too weak, the scattering through 90 Degree-Sign PA is actually so strong that the particles (electrons and protons/ions) are reflected and trapped in the turbulent magnetic fields. While the low-frequency nonresonant turbulence produces ubiquitous magnetic traps that only let through particles with the most field-aligned velocities, higher-frequency near-gyroscale turbulence, when present, enhances particle transport by allowing the particles to navigate between magnetic traps. Finally, visualizing both particle trajectories and MFLs in the very same turbulence reveals a powerful tool for understanding the effects of the turbulent fields on the particle dynamics and cross-field transport. Some cross-field-line scattering, strongly amplified by MFL dispersal, results in a strong cross-field scattering of the particles. From this visualization, it also appears that near-gyroscale turbulence, previously known as gyroresonant turbulence, does not resonantly interact with the particles. The interaction between particles and

  14. Large solar energetic particle event that occurred on 2012 March 7 and its VDA analysis

    NASA Astrophysics Data System (ADS)

    Ding, Liu-Guan; Cao, Xin-Xin; Wang, Zhi-Wei; Le, Gui-Ming

    2016-08-01

    On 2012 March 7, the STEREO Ahead and Behind spacecraft, along with near-Earth spacecraft (e.g. SOHO, Wind) situated between the two STEREO spacecraft, observed an extremely large global solar energetic particle (SEP) event in Solar Cycle 24. Two successive coronal mass ejections (CMEs) have been detected close in time. From the multi-point in-situ observations, it can be found that this SEP event was caused by the first CME, but the second one was not involved. Using velocity dispersion analysis (VDA), we find that for a well magnetically connected point, the energetic protons and electrons are released nearly at the same time. The path lengths to STEREO-B (STB) for protons and electrons have a distinct difference and deviate remarkably from the nominal Parker spiral path length, which is likely due to the presence of interplanetary magnetic structures situated between the source and STB. Also, the VDA method seems to only obtain reasonable results at well-connected locations and the inferred release times of energetic particles in different energy channels are similar. We suggest that good-connection is crucial for obtaining both an accurate release time and path length simultaneously, agreeing with the modeling result of Wang & Qin (2015).

  15. Energetic particle transport in the presence of magnetic turbulence: influence of spectral extension and intermittency

    NASA Astrophysics Data System (ADS)

    Pucci, F.; Malara, F.; Perri, S.; Zimbardo, G.; Sorriso-Valvo, L.; Valentini, F.

    2016-04-01

    The transport of energetic particles in the presence of magnetic turbulence is an important but unsolved problem of space physics and astrophysics. Here we aim at advancing the understanding of energetic particle transport by means of a new numerical model of synthetic magnetic turbulence. The model builds up a turbulent magnetic field as a superposition of space-localized fluctuations at different spatial scales. The resulting spectrum is isotropic with an adjustable spectral index. The model allows to reproduce a spectrum broader than four decades, and to regulate the level of intermittency through a technique based on the p-model. Adjusting the simulation parameters close to solar wind conditions at 1 AU, we inject ˜1 MeV protons in the turbulence realization and compute the parallel and perpendicular diffusion coefficients as a function of spectral extension, turbulence level, and intermittency. While a number of previous results are recovered in the appropriate limits, including anomalous transport regimes for low turbulence levels, we find that long spectral extensions tend to reduce the diffusion coefficients. Furthermore, we find for the first time that intermittency has an influence on parallel transport but not on perpendicular transport, with the parallel diffusion coefficient increasing with the level of intermittency. We also obtain the distribution of particle inversion times for parallel velocity, a power law for more than one decade, and compare it with the pitch angle scattering times observed in the solar wind. This parametric study can be useful to interpret particle propagation properties in astrophysical systems.

  16. Gyrokinetic simulation studies on the energetic-particle-induced geodesic acoustic mode

    NASA Astrophysics Data System (ADS)

    Miki, Kazuhiro; Idomura, Yasuhiro

    2014-10-01

    Understanding of the energetic particles physics is of great interest in the future burning plasmas. Particularly, particle loss in the presence of EGAM may be critical for ITER. We thus need to know how EGAM is excited and interacts with turbulence. We here introduce energetic particles in a full-f gyrokinetic code (GT5D). (i) We find linear dynamics of the EGAM driven by bump-on-tail particle distributions. We examine flat-q, homogeneous, axisymmetric, electrostatic gyrokinetic simulations. Above a certain level of the beam intensity, an oscillatory mode grows with about a half of the standard GAM. The observed frequencies are consistent with the eigenmode analyses derived from the perturbed gyrokinetic equations. The theoretical analyses also indicate a bifurcation of the excited modes depending on q-value. Estimation of the finite-orbit-width effects can provide a size dependency of the EGAM growth rate. (ii) We find linear and nonlinear dynamics of the EGAM driven by slowing-down distributions. We examine the axisymmetric gyrokinetic simulations with DIII-D-like parameters. The observed growth rates and frequencies are consistent with results of other hybrid code. Furthermore, we will focus on nonlinear phase space dynamics, namely chirping mode. This work is supported by HPCI Strategic Program Field No.4: Next-Generation Industrial Innovations, funded by the MEXT, Japan.

  17. SEPEM: A tool for statistical modeling the solar energetic particle environment

    NASA Astrophysics Data System (ADS)

    Crosby, Norma; Heynderickx, Daniel; Jiggens, Piers; Aran, Angels; Sanahuja, Blai; Truscott, Pete; Lei, Fan; Jacobs, Carla; Poedts, Stefaan; Gabriel, Stephen; Sandberg, Ingmar; Glover, Alexi; Hilgers, Alain

    2015-07-01

    Solar energetic particle (SEP) events are a serious radiation hazard for spacecraft as well as a severe health risk to humans traveling in space. Indeed, accurate modeling of the SEP environment constitutes a priority requirement for astrophysics and solar system missions and for human exploration in space. The European Space Agency's Solar Energetic Particle Environment Modelling (SEPEM) application server is a World Wide Web interface to a complete set of cross-calibrated data ranging from 1973 to 2013 as well as new SEP engineering models and tools. Both statistical and physical modeling techniques have been included, in order to cover the environment not only at 1 AU but also in the inner heliosphere ranging from 0.2 AU to 1.6 AU using a newly developed physics-based shock-and-particle model to simulate particle flux profiles of gradual SEP events. With SEPEM, SEP peak flux and integrated fluence statistics can be studied, as well as durations of high SEP flux periods. Furthermore, effects tools are also included to allow calculation of single event upset rate and radiation doses for a variety of engineering scenarios.

  18. Energetic particle transport in the presence of magnetic turbulence: influence of spectral extension and intermittency

    NASA Astrophysics Data System (ADS)

    Pucci, F.; Malara, F.; Perri, S.; Zimbardo, G.; Sorriso-Valvo, L.; Valentini, F.

    2016-07-01

    The transport of energetic particles in the presence of magnetic turbulence is an important but unsolved problem of space physics and astrophysics. Here, we aim at advancing the understanding of energetic particle transport by means of a new numerical model of synthetic magnetic turbulence. The model builds up a turbulent magnetic field as a superposition of space-localized fluctuations at different spatial scales. The resulting spectrum is isotropic with an adjustable spectral index. The model allows us to reproduce a spectrum broader than four decades, and to regulate the level of intermittency through a technique based on the p-model. Adjusting the simulation parameters close to solar wind conditions at 1 au, we inject ˜1 MeV protons in the turbulence realization and compute the parallel and perpendicular diffusion coefficients as a function of spectral extension, turbulence level, and intermittency. While a number of previous results are recovered in the appropriate limits, including anomalous transport regimes for low turbulence levels, we find that long spectral extensions tend to reduce the diffusion coefficients. Furthermore, we find for the first time that intermittency has an influence on parallel transport but not on perpendicular transport, with the parallel diffusion coefficient increasing with the level of intermittency. We also obtain the distribution of particle inversion times for parallel velocity, a power law for more than one decade, and compare it with the pitch angle scattering times observed in the solar wind. This parametric study can be useful to interpret particle propagation properties in astrophysical systems.

  19. Trapping of Solar Energetic Particles by Small-Scale Topology of Solar Wind Turbulence

    NASA Astrophysics Data System (ADS)

    Ruffolo, D.; Matthaeus, W. H.; Chuychai, P.

    2004-05-01

    The transport of energetic particles perpendicular to the mean magnetic field in space plasmas long has been viewed as a diffusive process. However, there is an apparent conflict between recent observations of solar energetic particles (SEP): 1) impulsive solar flares can exhibit ``dropouts" in which SEP intensity near Earth repeatedly disappears and reappears, indicating a filamentary distribution of SEPs and little diffusion across these boundaries. 2) Observations by the IMP-8 and Ulysses spacecraft, while they were on opposite sides of the Sun, showed similar time-intensity profiles for many SEP events, indicating rapid lateral diffusion of particles throughout the inner solar system within a few days. We explain these seemingly contradictory observations using a theoretical model, supported by computer simulations, in which many particles are temporarily trapped within topological structures in statistically homogeneous magnetic turbulence, and ultimately escape to diffuse at a much faster rate. This work was supported by the Thailand Research Fund, the Rachadapisek Sompoj Fund of Chulalongkorn University, and the NASA Sun-Earth Connections Theory Program (grant NAG5-8134).

  20. Observations of systematic temporal evolution in elemental composition during gradual solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Tylka, Allan J.; Reames, Donald V.; Ng, Chee K.

    The WIND/EPACT experiment offers a ˜100 fold increase in collecting power over instruments flown in previous solar cycles, thus allowing unprecedented detailed studies of temporal evolution in gradual solar energetic particle (SEP) events. We present hourly WIND/EPACT observations at ˜2-10 MeV/nuc from the 20 April 1998 and 26 August 1998 SEP events. These observations show striking patterns in elemental composition which evolve in a systematic fashion throughout the events' several-day durations. These data, combined with theoretical modeling in a companion Letter [Ng et al. 1999], suggest that a dynamic Alfvén wave field, generated primarily by streaming energetic protons, is responsible for the complex behavior which is observed.

  1. Correlation of Upper-Atmospheric 7-Be with Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Phillips, G. W.; Share, G. H.; King, S. E.; August, R. A.; Tylka, A. J.; Adams, J. H., Jr.; Panasyuk, M. I.; Nymmik, R. A.; Kuzhevskij, B. M.; Kulikauskas, V. S.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    A surprisingly large concentration of radioactive 7-Be was observed in the upper atmosphere at altitudes above 320 km on the LDEF satellite that was recovered in January 1990. We report on follow-up experiments on Russian spacecraft at altitudes of 167 to 370 km during the period of 1996 to 1999, specifically designed to measure 7-Be concentrations in low earth orbit. Our data show a significant correlation between the 7-Be concentration and the solar energetic proton fluence at Earth, but not with the overall solar activity. During periods of low solar proton fluence, the concentration is correlated with the galactic cosmic ray fluence. This indicates that spallation of atmospheric N by both solar energetic particles and cosmic rays is the primary source of 7-Be in the ionosphere.

  2. Energetic Charged Particle Emission from Hydrogen-Loaded pd and ti Cathodes and its Enhancement by He-4 Implantation

    NASA Astrophysics Data System (ADS)

    Lipson, A. G.; Miley, G. H.; Lipson, A. G.; Lyakhov, B. F.; Roussetski, A. S.

    2006-02-01

    In this paper, we demonstrate reproducible emissions of energetic alphas and protons appearing in an energy range where both cosmic ray interference and possible alpha emissions from contamination (e.g., radon) is assumed to be negligible. We also show that He4 doping of Pd and Ti cathodes leads to a significant enhancement of the energetic charged particles emission (ECPE). This measurement of the emissions of energetic (MeV) particles, in a region of low background interference plus their enhancement by He4 doping provides very strong support for the existence of LENR processes in the crystalline lattice of deuterated metals.

  3. Perpendicular Diffusion in the Transport of Solar Energetic Particles from Unconnected Sources: The Counter-streaming Particle Beams Revisited

    NASA Astrophysics Data System (ADS)

    He, H.-Q.

    2015-12-01

    In some solar energetic particle (SEP) events, a counter-streaming particle beam with a deep depression of flux at ∼ 90^\\circ pitch angle during the beginning phase is observed. Two different interpretations exist within the community to explain this interesting phenomenon. One explanation invokes the hypothesis of an outer reflecting boundary or a magnetic mirror beyond the observer. The other one considers the effect of perpendicular diffusion on the transport process of SEPs in interplanetary space. In this work, we revisit the problem of counter-streaming particle beams observed in SEP events and discuss the possible mechanisms responsible for the formation of this phenomenon. We clarify some results in previous works.

  4. Influence of the interplanetary shock on the radial dependence of solar energetic particle intensities

    NASA Astrophysics Data System (ADS)

    Aran, A.; Jacobs, C.; Sanahuja, B.; Lario, D.; Poedts, S.; Jiggens, P.

    2012-12-01

    The inclusion of a travelling shock as a source of energetic particles during gradual solar energetic particle (SEP) events is a key element to assess the radiation encountered by a mission in the inner heliosphere. We have developed, in the frame of the Solar Energetic Particle Environment Model (SEPEM) project, a two dimensional magnetohydrodynamic model to describe the shock propagation from 4 solar radii up to 1.6 AU. The outputs of this model are used to simulate the transport of SEPs from the shock front up to a given observer. The combination of the shock and particle transport models allows us to study the influence of both the shock properties and the observer's magnetic connection on the radial and longitudinal variation of proton peak intensities and fluences in gradual SEP events. We have simulated the propagation of four shocks characterized by two different transit times to 1 AU and two angular widths (narrow and wide). Two sets of seven spacecraft are placed along two nominal interplanetary magnetic field lines at radial distances ranging from 0.2 AU to 1.6 AU. The observers at 1 AU are located at central meridian and western positions with respect to the launch direction of the shocks. We calculate the resulting synthetic proton time-intensity profiles at several energies (5.0 < E < 200 MeV) measured by each virtual spacecraft. By tracking the shock from close to the Sun, we obtain the peak intensity of high-energy particles at the prompt component of the SEP events, without assuming ad-hoc conditions for particle injection at the corona. We discuss how the resulting power-law dependences of the peak intensities (and fluences) on the observer's radial distance vary with the particle energy, the characteristics of the shock, and the different evolving conditions for particle injection at the point of the shock front that magnetically connects to the observers. This information may contribute to improve the understanding of the peak intensities and

  5. Instability of dusty particle system in gas-discharge plasma

    SciTech Connect

    Filinov, V.S.; Petrov, O.F.; Fortov, V.E.; Molotkov, V.I.

    2005-10-31

    An effective anisotropic potential is proposed for the interaction between dust particles in a gas-discharge plasma. In addition to the Coulomb repulsion this potential takes into account attraction due to the spatial positive plasma charge originating from focusing of the ionic fluxes by dusty particles. The time evolution of the dust particle kinetic and potential energies from random initial configurations have been investigated by the Brownian dynamics method. Results of our simulation showed that the attraction between dusty particles can be the main physical reason of formation and decay of classical bound dust particle pairs and many particle complexes with low potential energy, while the kinetic energy (temperature) of unbound dust particles and particle oscillating in bound complexes may increase on three order as observed in experiments.

  6. Development of an integrated energetic neutral particle measurement system on experimental advanced full superconducting tokamak

    SciTech Connect

    Zhu, Y. B. Liu, D.; Heidbrink, W. W.; Zhang, J. Z.; Qi, M. Z.; Xia, S. B.; Wan, B. N.; Li, J. G.

    2014-11-15

    Full function integrated, compact silicon photodiode based solid state neutral particle analyzers (ssNPA) have been developed for energetic particle (EP) relevant studies on the Experimental Advanced Superconducting Tokamak (EAST). The ssNPAs will be mostly operated in advanced current mode with a few channels to be operated in conventional pulse-counting mode, aiming to simultaneously achieve individually proved ultra-fast temporal, spatial, and spectral resolution capabilities. The design details together with considerations on EAST specific engineering realities and physics requirements are presented. The system, including a group of single detectors on two vertical ports and two 16-channel arrays on a horizontal port, can provide both active and passive charge exchange measurements. ssNPA detectors, with variable thickness of ultra thin tungsten dominated foils directly deposited on the front surface, are specially fabricated and utilized to achieve about 22 keV energy resolution for deuterium particle detection.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  8. The simulation of radiation effects to astronauts due to solar energetic particles in deep space

    NASA Astrophysics Data System (ADS)

    Gang, Bao

    2012-02-01

    The exposure to interplanetary radiation poses a serious health risk to astronauts, especially for long-term missions. Protecting the astronauts from these particles has been the key issue to the manned space mission. High-energy space particles can penetrate the protective layer of a spacecraft, and probably cause deleterious effects to the astronauts. To estimate the size of these effects, a credible simulation of radioprotection is required. Using the Geant4 software toolkit, we have modeled the interaction processes and predicted the total energy deposit in a phantom (astronaut) as well as the similar information associated with secondary effects, due to Solar Energetic Particles (SEPs) at ∼1 AU caused by the large SEPs events in October 1989 and August 1972. In addition, we compared the characteristics of the energy deposit due to SEPs and Galactic Cosmic Rays (GCRs) and explained the differences between them by physical mechanism analysis.

  9. Shock acceleration of energetic particles in corotating interaction regions in the solar wind

    SciTech Connect

    Fisk, L.A.; Lee, M.A.

    1980-04-15

    A simple shock model for the acceleration of energetic particles in corotating interaction regions (CIRs) in the solar wind is presented. Particles are accelerated at the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream from the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. Particles also suffer adiabatic deceleration in the expanding solar wind, an effect not included in previous shock models for acceleration in CIRs. The model is able to account for the observed exponential spectra at Earth, the observed behavior of the spectra with radial distance, the observed radial gradients in the intensity, and the observed differences in the intensity and spectra at the forward and reverse shocks.

  10. Cross-field transport and pitch-angle anisotropy of solar energetic particles in MHD turbulence

    NASA Astrophysics Data System (ADS)

    Fraschetti, F.

    2016-01-01

    Recent modelling of solar energetic particles (SEPs) propagation through the heliospheric turbulence, also discussed in this workshop, has investigated the role of the pitch-angle scattering and the perpendicular transport in spreading particles in heliolongitude, as shown by multi-spacecraft measurements (STEREO A/B, ACE, SOHO, etc.) at 1 AU in various energy ranges. In some events the first-order pitch-angle anisotropy of the particles distribution is not-negligible. We calculate the average perpendicular displacement due to the gradient/curvature drift in an inhomogeneous turbulence accounting for pitch-angle dependence for two MHD turbulence models: (a) 3-D isotropic, (b) anisotropic as conjectured by Goldreich-Sridhar. We find in both cases that the drift scales as (1 - μ2)2 with the cosine of pitch-angle μ, in contrast with previous models for transport of SEPs. This result can impact the models of propagation of SEPs through the heliosphere.

  11. Energetic particle and gamma-ray generation in the solar matter

    NASA Astrophysics Data System (ADS)

    Kocharov, G. E.

    1983-08-01

    Observations and theoretical investigations of the physical characteristics of solar energetic particles, gamma rays, and neutrons are briefly reviewed. Attention is given to such topics as: the relationship between particle acceleration and the thermal and magnetic properties of the solar plasma; the energy spectra of cosmic rays; and the elemental and isotopic composition of solar particles. Observational data from the Solar Maximum Mission, Hinotori, and ISEE-3 satellites are discussed within the framework of current theories concerning the physical properties of solar gamma-rays and neutrons with energies above 0.3 MeV; photon emission from solar flares at energies above 10 MeV; and type II and type IV radio bursts due to gamma-ray line flares. The connection between proton and electron acceleration processes during the impulsive phase of a solar flare event is discussed in detail.

  12. Air shower simulation for WASAVIES: warning system for aviation exposure to solar energetic particles.

    PubMed

    Sato, T; Kataoka, R; Yasuda, H; Yashiro, S; Kuwabara, T; Shiota, D; Kubo, Y

    2014-10-01

    WASAVIES, a warning system for aviation exposure to solar energetic particles (SEPs), is under development by collaboration between several institutes in Japan and the USA. It is designed to deterministically forecast the SEP fluxes incident on the atmosphere within 6 h after flare onset using the latest space weather research. To immediately estimate the aircrew doses from the obtained SEP fluxes, the response functions of the particle fluxes generated by the incidence of monoenergetic protons into the atmosphere were developed by performing air shower simulations using the Particle and Heavy Ion Transport code system. The accuracy of the simulation was well verified by calculating the increase count rates of a neutron monitor during a ground-level enhancement, combining the response function with the SEP fluxes measured by the PAMELA spectrometer. The response function will be implemented in WASAVIES and used to protect aircrews from additional SEP exposure. PMID:24344351

  13. First Results on Pluto's Energetic Particle Environment from the PEPSSI Instrument

    NASA Astrophysics Data System (ADS)

    Kollmann, Peter; Hill, M. E.; McNutt, R.; Smith, H. T.; Vandegriff, J.; Kusterer, M.; Brown, L.; Haggerty, D. K.; Lisse, C. M.; Elliott, H. A.; Strobel, D.; Bagenal, F.; Sidrow, E.; McComas, D. J.; Horanyi, M.; Zirnstein, E.; Krimigis, S. M.; Ennico, K.; Young, L. A.; Weaver, H. A.; Olkin, C. B.; Stern, S. A.

    2015-11-01

    The New Horizons spacecraft flew by Pluto in July 2015 and passed through the wakes of Pluto and its largest moon Charon. Pluto interacts with the solar wind via the magnetic fields created by currents in its ionosphere and the pick-up of charge-exchange ions escaping from its atmosphere. The PEPSSI instrument (Pluto Energetic Particle Spectrometer Science Investigation) passed through this interaction region. Closest approach distance to Pluto was 11 Pluto radii, inside the orbit of Charon. PEPSSI measures intensities of keV to MeV ions and can distinguish ions in the solar wind from ions originating from Pluto. Pluto’s energetic particle environment clearly stands out compared to the surrounding solar wind at these heliospheric distances. Electrons in the same energy range as the ions do not show a distinct signature throughout the flyby. There is no indication in the particle observations for an intrinsic magnetic field of Pluto. We will present an analysis of the data that is downlinked throughout August and set them into context with measurements taken by PEPSSI in Jupiter’s magnetotail in 2007. This work was supported by NASA's New Horizons project.

  14. Robustness and flexibility in compact quasiaxial stellarators: Global ideal MHD stability and energetic particle transport

    SciTech Connect

    Redi, M.H.; Diallo, A.; Cooper, W.A.; Fu, G.Y.

    2000-01-27

    Concerns about the flexibility and robustness of a compact quasiaxial stellarator design are addressed by studying the effects of varied pressure and rotational transform profiles on expected performance. For thirty, related, fully three-dimensional configurations the global, ideal magnetohydrodynamic stability is evaluated as well as energetic particle transport. It is found that tokamak intuition is relevant to understanding the magnetohydrodynamic stability, with pressure gradient driving terms and shear stabilization controlling both the periodicity preserving, N=0, and the non-periodicity preserving, N=1, unstable kink modes. Global kink modes are generated by steeply peaked pressure profiles near the half radius and edge localized kink modes are found for plasmas with steep pressure profiles at the edge as well as with edge rotational transform above 0.5. Energetic particle transport is not strongly dependent on these changes of pressure and current (or rotational transform) profiles, although a weak inverse dependence on pressure peaking through the corresponding Shafranov shift is found. While good transport and MHD stability are not anticorrelated in these equilibria, stability only results from a delicate balance of the pressure and shear stabilization forces. A range of interesting MHD behaviors is found for this large set of equilibria, exhibiting similar particle transport properties.

  15. Upgraded Siberian Solar Radio Telescope: new opportunities to diagnose energetic particles in solar flares

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Alexey; Altyntsev, Alexander; Sergey, Lesovoi; Fleishman, Gregory

    Energetic electrons are a key factor of solar flares and therefore knowing their parameters is highly important for understanding the flare mechanisms and verifying the flare models. Radio emission offers multiple promising diagnostic tools, because this emission is produced by these energetic particles in the corona, at or near the particle acceleration sites. However, high diagnostic potential of radio observations has not yet been fully utilized due to two main reasons: (1) lack of well-calibrated observations with high spatial, spectral, and temporal resolutions and (2) lack of accurate and reliable theoretical models and fast numerical tools capable of recovering the emission source parameters from the radio data. Here we report on the recent and anticipated progress in both these science components - instrumentation and modeling. To this end the Siberian Solar Radio Telescope (Badary, Russia) is now being significantly upgraded in order to convert this instrument into a multi-wavelength imaging spectropolarimetry radioheliograph. At stage 1, the instrument will produce two-dimensional images of the Sun with high temporal and spatial resolution at five frequencies simultaneously in the 4-8 GHz range; this stage will be completed in 2015. Final (stage 2) configuration of the Upgraded Siberian Solar Radio Telescope (expected to be completed in 2019) will perform imaging observations at 15 frequencies in the 3-24 GHz range. At the same time, we are developing new theoretical methods and computer codes to analyze and interpret the anticipated observational data; the recent achievements include the "fast gyrosynchrotron codes", gyroresonance codes, and the 3D simulation tool "GX Simulator" freely available via the SSW distribution. In this presentation, we discuss the approaches to diagnosing the solar energetic particles with radio observations, including the recent advances and the opportunities coming from the construction of the Multiwavelength Siberian Solar

  16. Solar photospheric and coronal abundances from solar energetic particle measurements. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Breneman, H.

    1985-01-01

    Observations of solar energetic particles (SEP) from 22 solar flares in the 1977 to 1982 time period are reported. SEP abundances were obtained for all elements with 3 approximately less than Z approximately less than 30 except Li, Be, B, F, Sc, v, Co and Cu for which upper limits were obtained. Statistically meaningful abundances of several rare elements (P, Cl, K, Ti, and Mn) were determined for the first time, and the average abundance of the more abundant elements were determined with improved precision.

  17. An improved pulse-height analyzer for energetic particle measurements in the upper atmosphere

    NASA Technical Reports Server (NTRS)

    Dean, L.; Smith, L. G.

    1982-01-01

    An energetic particle spectrometer for measurements in the upper atmosphere by rocket is described. The system has two methods of processing data. One is a staircase generator using threshold detectors; the other is a peak detector. The system incorporates a logarithmic converter for better resolution at low amplitudes and better use of telemetry channels. The circuits are described and calibration procedures are given. Modifications are recommended for high flux environments. Appendices cover sampling error in the peak detector and modifications made to the receiver of the propagation experiment.

  18. Measurements of energetic particle radiation in transit to Mars on the Mars Science Laboratory.

    PubMed

    Zeitlin, C; Hassler, D M; Cucinotta, F A; Ehresmann, B; Wimmer-Schweingruber, R F; Brinza, D E; Kang, S; Weigle, G; Böttcher, S; Böhm, E; Burmeister, S; Guo, J; Köhler, J; Martin, C; Posner, A; Rafkin, S; Reitz, G

    2013-05-31

    The Mars Science Laboratory spacecraft, containing the Curiosity rover, was launched to Mars on 26 November 2011, and for most of the 253-day, 560-million-kilometer cruise to Mars, the Radiation Assessment Detector made detailed measurements of the energetic particle radiation environment inside the spacecraft. These data provide insights into the radiation hazards that would be associated with a human mission to Mars. We report measurements of the radiation dose, dose equivalent, and linear energy transfer spectra. The dose equivalent for even the shortest round-trip with current propulsion systems and comparable shielding is found to be 0.66 ± 0.12 sievert. PMID:23723233

  19. Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory

    NASA Astrophysics Data System (ADS)

    Zeitlin, C.; Hassler, D. M.; Cucinotta, F. A.; Ehresmann, B.; Wimmer-Schweingruber, R. F.; Brinza, D. E.; Kang, S.; Weigle, G.; Böttcher, S.; Böhm, E.; Burmeister, S.; Guo, J.; Köhler, J.; Martin, C.; Posner, A.; Rafkin, S.; Reitz, G.

    2013-05-01

    The Mars Science Laboratory spacecraft, containing the Curiosity rover, was launched to Mars on 26 November 2011, and for most of the 253-day, 560-million-kilometer cruise to Mars, the Radiation Assessment Detector made detailed measurements of the energetic particle radiation environment inside the spacecraft. These data provide insights into the radiation hazards that would be associated with a human mission to Mars. We report measurements of the radiation dose, dose equivalent, and linear energy transfer spectra. The dose equivalent for even the shortest round-trip with current propulsion systems and comparable shielding is found to be 0.66 ± 0.12 sievert.

  20. Early Results on Energetic Particle Precipitation Observed by the ABOVE Instrument Array

    NASA Astrophysics Data System (ADS)

    Cully, C. M.; Chaddock, D.; Daniel, C.; Davis, E.; Galts, D.; McGuffin, N.; Quinn, C.; Sheldon, A.; Wilson, C.

    2014-12-01

    ABOVE, the Array for Broadband Observations of VLF/ELF Emissions, is a network of radio instruments located across western Canada. The instruments monitor natural and artificial electromagnetic radiation in the frequency range from 200 Hz to 75 kHz. The primary scientific focus is on energetic particle precipitation: we infer precipitation into the atmosphere based on the observed amplitude and phase of remotely transmitted artificial signals, and simultanesouly monitor natural whistler-mode waves (chorus and hiss) that drive the precipitation. Instrument deployment began during the summer of 2014. We report here on the instrument design and the first results.

  1. Solar-stellar outer atmospheres and energetic particles, and galactic cosmic rays

    SciTech Connect

    Meyer, J.

    1985-01-01

    The heavy element compositions of the solar corona, solar wind (SW), solar energetic particles (SEP, ''mass-unbiasedd baseline''; Paper I) and galactic cosmic-ray sources (GCRS) are remarkably similar. They all show the same pattern as compared to standard local galactic (or solar photospheric) composition: an underabundance of heavy elements with first ionization potential (FIP) > or approx. =9 eV relative to elements with lower FIP, by factors of approx.4-6. Only C is clearly more abundant in GCR sources than in SEP (by a factor of approx.2-3), as well as possibly O.

  2. The lightweight energetic particle detector EPONA and its performance on Giotto

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Kirsch, E.; Thompson, A.; O'Sullivan, D.; Wenzel, K.-P.

    1987-06-01

    A lightweight energetic particle detector system (EPONA/EPA) is described, which was designed to operate in environmental conditions characterized by the varying solar aspect angles and temperatures pertaining during the cruise phase of the Giotto spacecraft and during the dust bombardment during closest approach (about 600 km) to the nucleus of comet Halley. Representative data, illustrating the functioning of EPONA during both the Giotto cruise phase and at comet encounter, are presented. The instrument has a wide range of applications to other space experiments where reliable plasma diagnostics are required.

  3. Modeling Mission-Specific Worst-Case Solar Energetic Particle Environments

    NASA Astrophysics Data System (ADS)

    Adams, J. H.; Dietrich, W. F.; Xapsos, M. A.

    2011-12-01

    To plan and design safe and reliable space missions, it is necessary to take into account the effects of the space radiation environment. The environment during large solar energetic particle events poses the greatest challenge to missions. As a starting point for planning and design, a reference environment must be specified representing the most challenging environment to be encountered during the mission at some confidence level. The engineering challenge is then to develop plans and mission design solutions that insure safe and reliable operations in this reference environment. This paper describes progress toward developing a model that provides such reference space radiation environments at user-specified confidence levels.

  4. Enhancement of hybrid rocket combustion performance using nano-sized energetic particles

    NASA Astrophysics Data System (ADS)

    Risha, Grant Alexander

    Until now, the regression rate of classical hybrid rocket engines have typically been an order of magnitude lower than solid propellant motors; thus, hybrids require a relatively large fuel surface area for a given thrust level. In addition to low linear regression rates, relatively low combustion efficiency (87 to 92%), low mass burning rates, varying oxidizer-to-fuel ratio during operation, and lack of scaling laws have been reported. These disadvantages can be ameliorated by introducing nano-sized energetic powder additives into the solid fuel. The addition of nano-sized energetic particles into the solid fuel enhances performance as measured by parameters such as: density specific impulse, mass and linear burning rates, and thrust. Thermophysical properties of the solid fuel such as density, heat of combustion, thermal diffusivity, and thermal conductivity are also enhanced. The types of nano-sized energetic particles used in this study include aluminum, boron, boron carbide, and some Viton-A coated particles. Since the combustion process of solid fuels in a hybrid rocket engine is governed by the mass flux of the oxidizer entering the combustion chamber, the rate-limiting process is the mixing and reacting of the pyrolysis products of the fuel grain with the incoming oxidizer. The overall goal of this research was to determine the relative propulsive and combustion behavior for a family of newly-developed HTPB-based solid-fuel formulations containing various nano-sized energetic particles. Seventeen formulations contained 13% additive by weight, one formulation (SF4) contained 6.5% additive by weight, and one formulation (SF19) contained 5.65% boron by weight. The two hybrid rocket engines which were used in this investigation were the Long Grain Center-Perforated (LGCP) rocket engine and the X-Ray Transparent Casing (XTC) rocket engine. The smaller scale LGCP rocket engine was used to evaluate all of the formulations because conducting experiments using the

  5. Multi-spacecraft observations of recurrent {sup 3}He-rich solar energetic particles

    SciTech Connect

    Bučík, R.; Innes, D. E.; Mall, U.; Korth, A.; Mason, G. M.; Gómez-Herrero, R.

    2014-05-01

    We study the origin of {sup 3}He-rich solar energetic particles (<1 MeV nucleon{sup –1}) that are observed consecutively on STEREO-B, Advanced Composition Explorer (ACE), and STEREO-A spacecraft when they are separated in heliolongitude by more than 90°. The {sup 3}He-rich period on STEREO-B and STEREO-A commences on 2011 July 1 and 2011 July 16, respectively. The ACE {sup 3}He-rich period consists of two sub-events starting on 2011 July 7 and 2011 July 9. We associate the STEREO-B July 1 and ACE July 7 {sup 3}He-rich events with the same sizeable active region (AR) producing X-ray flares accompanied by prompt electron events, when it was near the west solar limb as seen from the respective spacecraft. The ACE July 9 and STEREO-A July 16 events were dispersionless with enormous {sup 3}He enrichment, lacking solar energetic electrons and occurring in corotating interaction regions. We associate these events with a small, recently emerged AR near the border of a low-latitude coronal hole that produced numerous jet-like emissions temporally correlated with type III radio bursts. For the first time we present observations of (1) solar regions with long-lasting conditions for {sup 3}He acceleration and (2) solar energetic {sup 3}He that is temporarily confined/re-accelerated in interplanetary space.

  6. LIMITS ON ALPHA PARTICLE TEMPERATURE ANISOTROPY AND DIFFERENTIAL FLOW FROM KINETIC INSTABILITIES: SOLAR WIND OBSERVATIONS

    SciTech Connect

    Bourouaine, Sofiane; Verscharen, Daniel; Chandran, Benjamin D. G.; Maruca, Bennett A.; Kasper, Justin C.

    2013-11-01

    Previous studies have shown that the observed temperature anisotropies of protons and alpha particles in the solar wind are constrained by theoretical thresholds for pressure and anisotropy driven instabilities such as the Alfvén/ion-cyclotron (A/IC) and fast-magnetosonic/whistler (FM/W) instabilities. In this Letter, we use a long period of in situ measurements provided by the Wind spacecraft's Faraday cups to investigate the combined constraint on the alpha proton differential flow velocity and the alpha particle temperature anisotropy due to A/IC and FM/W instabilities. We show that the majority of the data are constrained to lie within the region of parameter space in which A/IC and FM/W waves are either stable or have extremely low growth rates. In the minority of observed cases in which the growth rate of the A/IC (FM/W) instability is comparatively large, we find relatively higher values of T {sub α}/T {sub p} (T {sub ∥α}/T {sub ∥p}) when the alpha proton differential flow velocity is small, where T {sub α} and T {sub p} (T {sub ∥α} and T {sub ∥p}) are the perpendicular (parallel) temperatures of alpha particles and protons. We conjecture that this observed feature might arise from preferential alpha particle heating which can drive the alpha particles beyond the instability thresholds.

  7. Particles with Tunable Porosity and Morphology by Controlling Interfacial Instability in Block Copolymer Emulsions.

    PubMed

    Ku, Kang Hee; Shin, Jae Man; Klinger, Daniel; Jang, Se Gyu; Hayward, Ryan C; Hawker, Craig J; Kim, Bumjoon J

    2016-05-24

    A series of porous block copolymer (BCP) particles with controllable morphology and pore sizes was fabricated by tuning the interfacial behavior of BCP droplets in oil-in-water emulsions. A synergistic adsorption of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) BCPs and sodium dodecyl sulfate (SDS) to the surface of the emulsion droplet induced a dramatic decrease in the interfacial tension and generated interfacial instability at the particle surface. In particular, the SDS concentration and the P4VP volume fraction of PS-b-P4VP were key parameters in determining the degree of interfacial instability, leading to different types of particles including micelles, capsules, closed-porosity particles, and open-porosity particles with tunable pore sizes ranging from 10 to 500 nm. The particles with open-porosity could be used as pH-responsive, high capacity delivery systems where the uptake and release of multiple dyes could be achieved. PMID:27138967

  8. Particle beam self-modulation instability in tapered and inhomogeneous plasma

    SciTech Connect

    Schroeder, Carl; Benedetti, Carlo; Esarey, Eric; Gruener, Florian; Leemans, Wim

    2011-12-28

    The particle beam self-modulation instability in tapered and inhomogeneous plasmas is analyzed via an evolution equation for the beam radius. For a sufficiently fast taper the instability is suppressed, and the condition for growth suppression is derived. The form of the taper to phase lock a trailing witness bunch in the plasma wave driven by a self-modulated beam is determined, which can increase the energy gain by several orders of magnitude. Growth of the instability places stringent constraints on the initial background plasma density fluctuations.

  9. Particle beam self-modulation instability in tapered and inhomogeneous plasma

    SciTech Connect

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; Leemans, W. P.; Gruener, F. J.

    2012-01-15

    The particle beam self-modulation instability in tapered and inhomogeneous plasmas is analyzed via an evolution equation for the beam radius. For a sufficiently fast taper, the instability is suppressed, and the condition for growth suppression is derived. The form of the taper to phase lock a trailing witness bunch in the plasma wave driven by a self-modulated beam is determined, which can increase the energy gain by several orders of magnitude. Growth of the instability places stringent constraints on the initial background plasma density fluctuations.

  10. AN EFFECT OF PERPENDICULAR DIFFUSION ON THE ANISOTROPY OF SOLAR ENERGETIC PARTICLES FROM UNCONNECTED SOURCES

    SciTech Connect

    Qin, G.; He, H.-Q.; Zhang, M. E-mail: hqhe@spaceweather.ac.cn

    2011-09-01

    Recently, Tan and coworkers studied the 2001 September 24 solar energetic particle (SEP) event observed by the Wind spacecraft at 1 AU and found that there is a counter-streaming particle beam with a deep depression of flux at 90{sup 0} pitch angle during the beginning of the event. They suggested that it is a result of a reflecting boundary at some distance outside of 1 AU. While this scenario could be true under some specific configuration of an interplanetary magnetic field, in this paper we offer another possible explanation. We simulated the SEP event by solving the five-dimensional focused transport equation numerically for 40 keV electrons with perpendicular diffusion. We find that a counter-streaming particle beam with deep depression at 90{sup 0} pitch angle can form on Parker magnetic field lines that do not directly connect to the main particle source on the Sun in the beginning of an SEP event. It can happen when a significant number of observed particles come from adjacent field lines through parallel transport to large radial distance first, hopping across field lines through perpendicular diffusion, and then getting scattered back to 1 AU, where they combine with the particles directly coming from the Sun to form a counter-streaming beam.

  11. Modeling transport of energetic particles in corotating interaction regions: A case study

    NASA Astrophysics Data System (ADS)

    Zhao, Lulu; Li, Gang; Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; Mason, G. M.; Wu, Z.; Chen, Y.

    2016-01-01

    We investigate energetic particle transport in corotating interaction regions (CIRs) through a case study. The CIR event we study occurred on 8 February 2008 and was observed by both the Advanced Composition Explorer (ACE) and the twin Solar TErrestrial RElations Observatory (STEREO) B spacecraft. An in situ reverse shock was observed by STEREO B (1.0 AU) but not ACE (0.98 AU). Using STEREO B observations and assuming the CIR structure does not vary significantly in the corotating frame, we estimate the shock location at later times for both the STEREO B and ACE observations. Further assuming the accelerated particle spectral shape at the shock does not vary with shock location, we calculate the particle differential intensities as observed by ACE and STEREO B at two different times by solving the focused transport equation using a Monte Carlo simulation. We assume that particles move along Parker's field and experience no cross-field diffusion. We find that the modulation of sub-MeV/nucleon particles is significant. To obtain reasonable comparisons between the simulations and the observations by both ACE and STEREO B, one has to assume that the CIR shock can accelerate more particles at a larger heliocentric distance than at a smaller heliocentric distance.

  12. External front instabilities induced by a shocked particle ring.

    PubMed

    Rodriguez, V; Saurel, R; Jourdan, G; Houas, L

    2014-10-01

    The dispersion of a cylindrical particle ring by a blast or shock wave induces the formation of coherent structures which take the form of particle jets. A blast wave, issuing from the discharge of a planar shock wave at the exit of a conventional shock tube, is generated in the center of a granular medium ring initially confined inside a Hele-Shaw cell. With the present experimental setup, under impulsive acceleration, a solid particle-jet formation is observed in a quasi-two-dimensional configuration. The aim of the present investigation is to observe in detail the formation of very thin perturbations created around the external surface of the dispersed particle layer. By means of fast flow visualization with an appropriate recording window, we focus solely on the first instants during which the external particle ring becomes unstable. We find that the critical area of the destabilization of the external ring surface is constant regardless of the acceleration of the initial layer. Moreover, we observe in detail the external front perturbation wavelength, rendered dimensionless by the initial ring perimeter, and follow its evolution with the initial particle layer acceleration. We report this quantity to be constant regardless of the evolution of the initial particle layer acceleration. Finally, we can reasonably assert that external front perturbations depend solely on the material of the particles. PMID:25375599

  13. External front instabilities induced by a shocked particle ring

    NASA Astrophysics Data System (ADS)

    Rodriguez, V.; Saurel, R.; Jourdan, G.; Houas, L.

    2014-10-01

    The dispersion of a cylindrical particle ring by a blast or shock wave induces the formation of coherent structures which take the form of particle jets. A blast wave, issuing from the discharge of a planar shock wave at the exit of a conventional shock tube, is generated in the center of a granular medium ring initially confined inside a Hele-Shaw cell. With the present experimental setup, under impulsive acceleration, a solid particle-jet formation is observed in a quasi-two-dimensional configuration. The aim of the present investigation is to observe in detail the formation of very thin perturbations created around the external surface of the dispersed particle layer. By means of fast flow visualization with an appropriate recording window, we focus solely on the first instants during which the external particle ring becomes unstable. We find that the critical area of the destabilization of the external ring surface is constant regardless of the acceleration of the initial layer. Moreover, we observe in detail the external front perturbation wavelength, rendered dimensionless by the initial ring perimeter, and follow its evolution with the initial particle layer acceleration. We report this quantity to be constant regardless of the evolution of the initial particle layer acceleration. Finally, we can reasonably assert that external front perturbations depend solely on the material of the particles.

  14. Generating energetic electrons through staged acceleration in the two-plasmon-decay instability in inertial confinement fusion.

    PubMed

    Yan, R; Ren, C; Li, J; Maximov, A V; Mori, W B; Sheng, Z-M; Tsung, F S

    2012-04-27

    A new hot-electron generation mechanism in two-plasmon-decay instabilities is described based on a series of 2D, long-term (~10 ps) particle-in-cell and fluid simulations under parameters relevant to inertial confinement fusion. The simulations show that significant laser absorption and hot-electron generation occur in the nonlinear stage. The hot electrons are stage accelerated from the low-density region to the high-density region. New modes with small phase velocities develop in the low-density region in the nonlinear stage and form the first stage for electron acceleration. Electron-ion collisions are shown to significantly reduce the efficiency of this acceleration mechanism. PMID:22680873

  15. Inverse Saffman-Taylor Experiments with Particles Lead to Capillarity Driven Fingering Instabilities.

    PubMed

    Bihi, Ilyesse; Baudoin, Michael; Butler, Jason E; Faille, Christine; Zoueshtiagh, Farzam

    2016-07-15

    Using air to displace a viscous fluid contained in a Hele-Shaw cell can create a fingering pattern at the interface between the fluids if the capillary number exceeds a critical value. This Saffman-Taylor instability is revisited for the inverse case of a viscous fluid displacing air when partially wettable hydrophilic particles are lying on the walls. Though the inverse case is otherwise stable, the presence of the particles results in a fingering instability at low capillary number. This capillary-driven instability is driven by the integration of particles into the interface which results from the minimization of the interfacial energy. Both axisymmetric and rectangular geometries are considered in order to quantify this phenomenon. PMID:27472115

  16. Inverse Saffman-Taylor Experiments with Particles Lead to Capillarity Driven Fingering Instabilities

    NASA Astrophysics Data System (ADS)

    Bihi, Ilyesse; Baudoin, Michael; Butler, Jason E.; Faille, Christine; Zoueshtiagh, Farzam

    2016-07-01

    Using air to displace a viscous fluid contained in a Hele-Shaw cell can create a fingering pattern at the interface between the fluids if the capillary number exceeds a critical value. This Saffman-Taylor instability is revisited for the inverse case of a viscous fluid displacing air when partially wettable hydrophilic particles are lying on the walls. Though the inverse case is otherwise stable, the presence of the particles results in a fingering instability at low capillary number. This capillary-driven instability is driven by the integration of particles into the interface which results from the minimization of the interfacial energy. Both axisymmetric and rectangular geometries are considered in order to quantify this phenomenon.

  17. On the Influence of the Geomagnetic Field Geometry on the Propagation of Charged Energetic Particles

    NASA Astrophysics Data System (ADS)

    Herbst, K.; Kopp, A.; Heber, B.

    2011-12-01

    Studies of the propagation of charged energetic particles in the Earth's magnetic field go back to Carl Størmer, who introduced ''allowed'' and ''forbidden'' regions on the Earth's surface, leading finally to the definition of the cutoff rigidity, i.e. the minimum momentum per charge a particle must have in order to reach a certain geographical point. Employing Monte Carlo Simulations with the PLANETOCOSMICS code we investigate the correlation between the geomagnetic field structure and the (vertical) cutoff rigidity. It turns out that the resulting rigidity maps reflect the geometry of the field, rather than its magnitude, where the field geometry is represented by the difference between the tangential and the radial components. In order to support our findings we also investigate the temporal variation of both quantities over the last century.

  18. Bimodal abundances in the energetic particles of solar and interplanetary origin

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1988-01-01

    This letter reports the first results from an examination of the daily-averaged abundances of the elements from H through Fe as well as electrons and isotopes of He in energetic particles observed in interplanetary space by the ISEE 3 spacecraft over an 8.5 yr period. The abundances of heavy elements such as Fe/O show, for the first time, clear evidence of the presence of two distinct populations of particles. Earlier observations could be interpreted as extreme variations within a single population. The population with enhanced Fe/O shows correlated enhancements in He-3/He-4, p/e, and He/H. This population is consistent with material that has been processed to high temperatures in the impulsively heated regions of solar flares. The second population, with more normal abundances, is probably accelerated from ambient material by coronal and interplanetary shocks.

  19. Effective lifetime of NOx produced by energetic particle precipitation in the winter hemisphere

    NASA Astrophysics Data System (ADS)

    Antonius Marszalek, Markus; Nesse Tyssøy, Hilde; Hibbins, Robert; Ødegaard, Linn-Krisitine; Sandanger, Marit; Stadsnes, Johan

    2015-04-01

    Energetic particle precipitation (EPP) into the atmosphere impacts the chemical composition in the middle atmosphere. However, the EPP effects are not restrained to the area it is produced, but will be transported both horizontally and vertically by the background winds and waves. To address the aspect of horizontal transport we use the simple empirical horizontal wind model, HWM07, to trace the approximate trajectories the air parcels take around the polar region. We limit our focus to the winter hemisphere. We parameterize the NOx production based on the energy deposition estimated from particle measurements on the NOAA Polar Orbiting Environmental Satellites (POES). We estimate the evolution of the EPP-produced NOx taking into consideration sunlight exposure. The results give a rough estimate of the lifetime of NOx produced during a precipitation event and its hemispherical distribution in the aftermath of an event compared to its local production.

  20. Identification of the energetic-particle driven GAM in the LHD

    NASA Astrophysics Data System (ADS)

    Ido, T.; Osakabe, M.; Shimizu, A.; Watari, T.; Nishiura, M.; Toi, K.; Ogawa, K.; Itoh, K.; Yamada, I.; Yasuhara, R.; Yoshimura, Y.; Kato, S.; The LHD Experiment Group

    2015-08-01

    n = 0 modes with frequency chirping have been observed by a heavy ion beam probe and Mirnov coils in the large helical device plasmas, where n is the toroidal mode number. The spatial structures of the electrostatic potential fluctuation and the density fluctuation correspond to those of the geodesic acoustic mode (GAM). The modes are observed only during the tangential neutral beam injection with the energy of 175 keV. The energy spectra of fast ions measured by a neutral particle analyzer implies that the modes are excited by the fast ions through the inverse Landau damping. The absolute values and the temperature dependence of the frequency of the mode can be interpreted by the dispersion relation taking into account the measured energy spectra of the fast ions. Therefore, the observed n = 0 modes are identified as the energetic-particle driven GAM.

  1. A rocket-borne pulse-height analyzer for energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Leung, W.; Smith, L. G.; Voss, H. D.

    1979-01-01

    The pulse-height analyzer basically resembles a time-sharing multiplexing data-acquisition system which acquires analog data (from energetic particle spectrometers) and converts them into digital code. The PHA simultaneously acquires pulse-height information from the analog signals of the four input channels and sequentially multiplexes the digitized data to a microprocessor. The PHA together with the microprocessor form an on-board real-time data-manipulation system. The system processes data obtained during the rocket flight and reduces the amount of data to be sent back to the ground station. Consequently the data-reduction process for the rocket experiments is speeded up. By using a time-sharing technique, the throughput rate of the microprocessor is increased. Moreover, data from several particle spectrometers are manipulated to share one information channel; consequently, the TM capacity is increased.

  2. The response of energetic particles to nightside magnetic pulsations as seen by AMPTE/CCE

    NASA Technical Reports Server (NTRS)

    Lopez, R. E.; Engebretson, M. J.; Mcentire, R. W.; Lui, A. T. Y.; Zanetti, L. J.

    1986-01-01

    This paper reports the response of energetic ions during two types of magnetic oscillations: an azimuthal fluctuation and a radial fluctuation, both with periods in the Pc4-Pc5 range. The azimuthal oscillations occur on April 30, 1985 from 0950 to 1210 UT at 8.7 to 7.0 R(E) and from 1.5 to 2.8 MLT. The radial oscillations occur on April 26, 1985 from 1200 to 1400 UT at 8.7 to 7.5 R(E) and from 2.2 to 3.0 MLT. In this case the particles show in phase periodic flux variations in sectors with radial gradients in the flux. These particle fluctuations represent two distinct modulations, each associated with a basic mode of magnetic oscillation in the near-earth magnetotail.

  3. Dissipation of Magnetohydrodynamic Waves on Energetic Particles: Impact on Interstellar Turbulence and Cosmic Ray Transport

    SciTech Connect

    Ptuskin, V.S.; Moskalenko, Igor V.; Jones, F.C.; Strong, A.W.; Zirakashvili, V.N.; /Troitsk, IZMIRAN /Heidelberg, Max Planck Inst. Astron.

    2006-01-17

    The physical processes involved in diffusion of Galactic cosmic rays in the interstellar medium are addressed. We study the possibility that the nonlinear MHD cascade sets the power-law spectrum of turbulence which scatters charged energetic particles. We find that the dissipation of waves due to the resonant interaction with cosmic ray particles may terminate the Kraichnan-type cascade below wavelengths 10{sup 13} cm. The effect of this wave dissipation has been incorporated in the GALPROP numerical propagation code in order to asses the impact on measurable astrophysical data. The energy-dependence of the cosmic-ray diffusion coefficient found in the resulting self-consistent model may explain the peaks in the secondary to primary nuclei ratios observed at about 1 GeV/nucleon.

  4. Numerical and analytic models of spontaneous frequency sweeping for energetic particle-driven Alfven eigenmodes

    NASA Astrophysics Data System (ADS)

    Wang, Ge; Berk, H. L.

    2011-10-01

    The frequency chirping signal arising from spontaneous a toroidial Alfven eigenmode (TAE) excited by energetic particles is studied for both numerical and analytic models. The time-dependent numerical model is based on the 1D Vlasov equation. We use a sophisticated tracking method to lock onto the resonant structure to enable the chirping frequency to be nearly constant in the calculation frame. The accuracy of the adiabatic approximation is tested during the simulation which justifies the appropriateness of our analytic model. The analytic model uses the adiabatic approximation which allows us to solve the wave evolution equation in frequency space. Then, the resonant interactions between energetic particles and TAE yield predictions for the chirping rate, wave frequency and amplitudes vs. time. Here, an adiabatic invariant J is defined on the separatrix of a chirping mode to determine the region of confinement of the wave trapped distribution function. We examine the asymptotic behavior of the chirping signal for its long time evolution and find agreement in essential features with the results of the simulation. Work supported by Department of Energy contract DE-FC02-08ER54988.

  5. Are CME 'interactions' Really Important for Accelerating Major Solar Energetic Particle Events?

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Lawrence, G. R.; Haggerty, D. K.; Kucera, T.; Szabo, A.

    2002-01-01

    Recent studies have proposed that the presence or absence of an interaction with a preceding coronal mass ejection (CME) or other coronal structure within approximately 50R(sub s), of the Sun discriminates large, fast CMEs associated with major solar energetic particle (SEP) events from those that are not. We conclude that there is no compelling evidence that, if such interactions take place, they play an important role in SEP acceleration. Reasons include: The reported statistical results are consistent with a chance association between interacting CMEs and SEP events; Energetic SEPs are detected at Earth typically before or around the time when the primary CME enters the LASCO C2 field of view - interactions higher in the corona cannot play a role in acceleration of these particles; For approximately 60% of major SEP events in 1997-2001, the preceding CME fades into the background corona or is relatively narrow (less than 40 deg), suggesting any interaction will be weak; Radio signatures attributed to CME interaction occur after SEP acceleration has commenced.

  6. GRADUAL SOLAR ENERGETIC PARTICLE EVENT ASSOCIATED WITH A DECELERATING SHOCK WAVE

    SciTech Connect

    Kocharov, L.; Laitinen, T.; Al-Sawad, A.; Saloniemi, O.; Valtonen, E.; Reiner, M. J.

    2009-07-20

    On 2000 April 4-6 the Energetic and Relativistic Nuclei and Electron particle telescope on the Solar and Heliospheric Observatory spacecraft observed a major solar energetic particle (SEP) event associated with two coronal mass ejections (CMEs) separated by approximately 8 hr. The first CME was accompanied by a low-frequency type II radio burst observed by the WAVES receivers on the Wind spacecraft. Analysis of the high-precision measurements of the {approx}20 MeV proton flux anisotropy, model fitting of the type II dynamic spectrum, and SEP transport modeling support the idea that the shock wave of the first CME was an efficient accelerator for {approx}20 MeV protons during only the first 6 hr after the launch. This shock gradually slowed down, weakened, and became transparent for the protons produced by the second eruption behind the previous CME. The main production of SEPs due to the two successive eruptions continued together for 12 hr. The near-Earth SEP event was additionally amplified by the SEP mirroring in the interplanetary magnetic field draping at the edge of an old CME beyond the Earth's orbit, which made the SEP intensity-time profiles more prolonged than would be expected based on the assumption of SEP transport in the standard solar wind.

  7. A model for the behaviour of the Solar Energetic Particle Events inside Magnetic Clouds

    NASA Astrophysics Data System (ADS)

    Medina, J.; Hidalgo, M. A.

    2006-12-01

    The modulation effects of the solar ejecta over the solar energetic particle event SEPe fluxes (0,5-100 MeV) provided by solar flares have recently been highlighted. Especially important is the behaviour of these fluxes inside MCs where, in spite of the low magnetic field intensities of these interplanetary structures (about 30 nT), a decrease in the population of the energetic particles is observed. In the present work it is shown a simple theoretical model we have developed to analyse the behaviour of those fluxes inside the magnetic clouds (MCs) using, as a starting point, our previous magnetic field model for MCs. The experimental data from ACE, GOES, SAMPEX, SOHO, Ulysses and WIND satellites are presented, both from MC coincident with SEPe and not coincident. This work has been supported by the Spanish Comisión Internacional de Ciencia y Tecnología (CICYT), grant ESP2005-07290-C02-01 and ESP2006-08459 and Madrid Autonomous Community / University of Alcala grant CAM-UAH 2005/007. This work is performed inside COST Action 724.

  8. Local wave particle resonant interaction causing energetic particle prompt loss in DIII-D plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, R. B.; Fu, G. Y.; White, R. B.; Wang, X. G.

    2015-11-01

    A new wave particle resonance mechanism is found explaining the first-orbit prompt neutral beam-ion losses induced by shear Alfvén Eigenmodes (AEs) in the DIII-D tokamak. Because of the large banana width, a typical trapped beam ion can only interact locally with a core localised Alfvén Eigenmode for a fraction of its orbit, i.e. part of its inner leg of the banana orbit. These trapped beam ions can experience substantial radial kick within one bounce as long as the phases of the wave seen by the particles are nearly constant during this local interaction. A wave particle resonant condition is found based on the locally averaged particle orbit frequencies over the interaction part of the particle orbit. It is further found that the frequency width of the local resonance is quite large because the interaction time is short. This implies that particles over a considerable region of phase space can interact effectively with the localised AEs and experience large radial kicks within one bounce orbit. The radial kick size is found numerically and analytically to scale linearly in AE amplitude and is about 5 cm for typical experimental parameters. These results are consistent with experimental measurement.

  9. The Longitudinal Properties of a Solar Energetic Particle Event Investigated Using Modern Solar Imaging

    NASA Technical Reports Server (NTRS)

    Rouillard, A. P.; Sheeley, N.R. Jr.; Tylka, A.; Vourlidas, A.; Ng, C. K.; Rakowski, C.; Cohen, C. M. S.; Mewaldt, R. A.; Mason, G. M.; Reames, D.; Savani, N. P.; StCyr, O. C.; Szabo, A.

    2012-01-01

    We use combined high-cadence, high-resolution, and multi-point imaging by the Solar-Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory to investigate the hour-long eruption of a fast and wide coronal mass ejection (CME) on 2011 March 21 when the twin STEREO spacecraft were located beyond the solar limbs. We analyze the relation between the eruption of the CME, the evolution of an Extreme Ultraviolet (EUV) wave, and the onset of a solar energetic particle (SEP) event measured in situ by the STEREO and near-Earth orbiting spacecraft. Combined ultraviolet and white-light images of the lower corona reveal that in an initial CME lateral "expansion phase," the EUV disturbance tracks the laterally expanding flanks of the CME, both moving parallel to the solar surface with speeds of approx 450 km/s. When the lateral expansion of the ejecta ceases, the EUV disturbance carries on propagating parallel to the solar surface but devolves rapidly into a less coherent structure. Multi-point tracking of the CME leading edge and the effects of the launched compression waves (e.g., pushed streamers) give anti-sunward speeds that initially exceed 900 km/s at all measured position angles. We combine our analysis of ultraviolet and white-light images with a comprehensive study of the velocity dispersion of energetic particles measured in situ by particle detectors located at STEREO-A (STA) and first Lagrange point (L1), to demonstrate that the delayed solar particle release times at STA and L1 are consistent with the time required (30-40 minutes) for the CME to perturb the corona over a wide range of longitudes. This study finds an association between the longitudinal extent of the perturbed corona (in EUV and white light) and the longitudinal extent of the SEP event in the heliosphere.

  10. THE LONGITUDINAL PROPERTIES OF A SOLAR ENERGETIC PARTICLE EVENT INVESTIGATED USING MODERN SOLAR IMAGING

    SciTech Connect

    Rouillard, A. P.; Sheeley, N. R.; Tylka, A.; Vourlidas, A.; Rakowski, C.; Ng, C. K.; Cohen, C. M. S.; Mewaldt, R. A.; Mason, G. M.; Reames, D.; Savani, N. P.; StCyr, O. C.; Szabo, A.

    2012-06-10

    We use combined high-cadence, high-resolution, and multi-point imaging by the Solar-Terrestrial Relations Observatory (STEREO) and the Solar and Heliospheric Observatory to investigate the hour-long eruption of a fast and wide coronal mass ejection (CME) on 2011 March 21 when the twin STEREO spacecraft were located beyond the solar limbs. We analyze the relation between the eruption of the CME, the evolution of an Extreme Ultraviolet (EUV) wave, and the onset of a solar energetic particle (SEP) event measured in situ by the STEREO and near-Earth orbiting spacecraft. Combined ultraviolet and white-light images of the lower corona reveal that in an initial CME lateral 'expansion phase', the EUV disturbance tracks the laterally expanding flanks of the CME, both moving parallel to the solar surface with speeds of {approx}450 km s{sup -1}. When the lateral expansion of the ejecta ceases, the EUV disturbance carries on propagating parallel to the solar surface but devolves rapidly into a less coherent structure. Multi-point tracking of the CME leading edge and the effects of the launched compression waves (e.g., pushed streamers) give anti-sunward speeds that initially exceed 900 km s{sup -1} at all measured position angles. We combine our analysis of ultraviolet and white-light images with a comprehensive study of the velocity dispersion of energetic particles measured in situ by particle detectors located at STEREO-A (STA) and first Lagrange point (L1), to demonstrate that the delayed solar particle release times at STA and L1 are consistent with the time required (30-40 minutes) for the CME to perturb the corona over a wide range of longitudes. This study finds an association between the longitudinal extent of the perturbed corona (in EUV and white light) and the longitudinal extent of the SEP event in the heliosphere.

  11. Electromagnetic Weibel Instability in Intense Charged Particle Beams with Large Energy Anisotropy

    SciTech Connect

    Edward A. Startsev; Ronald C. Davidson

    2003-10-20

    In plasmas with strongly anisotropic distribution functions, collective instabilities may develop if there is sufficient coupling between the transverse and longitudinal degrees of freedom. Our previous numerical and theoretical studies of intense charged particle beams with large temperature anisotropy [E. A. Startsev, R. C. Davidson and H. Qin, PRSTAB, 6, 084401 (2003); Phys. Plasmas 9, 3138 (2002)] demonstrated that a fast, electrostatic, Harris-like instability develops, and saturates nonlinearly, for sufficiently large temperature anisotropy (T{sub {perpendicular}b}/T{sub {parallel}b} >> 1). The total distribution function after saturation, however, is still far from equipartitioned. In this paper the linearized Vlasov-Maxwell equations are used to investigate detailed properties of the transverse electromagnetic Weibel-type instability for a long charge bunch propagating through a cylindrical pipe of radius r{sub w}. The kinetic stability analysis is carried out for azimuthally symmetric perturbations about a two-temperature thermal equilibrium distribution in the smooth-focusing approximation. The most unstable modes are identified, and their eigenfrequencies, radial mode structure and instability thresholds are determined. The stability analysis shows that, although there is free energy available to drive the electromagnetic Weibel instability, the finite transverse geometry of the charged particle beam introduces a large threshold value for the temperature anisotropy ((T{sub {perpendicular}b}/T{sub {parallel}b}){sup Weibel} >> (T{sub {perpendicular}b}/T{sub {parallel}b}){sup Harris}) below which the instability is absent. Hence, unlike the case of an electrically neutral plasma, the Weibel instability is not expected to play as significant a role in the process of energy isotropization of intense unneutralized charged particle beams as the electrostatic Harris-type instability.

  12. Electromagnetic Weibel instability in intense charged particle beams with large energy anisotropy

    NASA Astrophysics Data System (ADS)

    Startsev, Edward A.; Davidson, Ronald C.

    2003-12-01

    In plasmas with strongly anisotropic distribution functions, collective instabilities may develop if there is sufficient coupling between the transverse and longitudinal degrees of freedom. Our previous numerical and theoretical studies of intense charged particle beams with large temperature anisotropy [E. A. Startsev, R. C. Davidson, and H. Qin, Phys. Rev. ST Accel. Beams 6, 084401 (2003); Phys. Plasmas 9, 3138 (2002)] demonstrated that a fast, electrostatic, Harris-type instability develops, and saturates nonlinearly, for sufficiently large temperature anisotropy (T⊥b/T∥b≫1). The total distribution function after saturation, however, is still far from equipartitioned. In this paper the linearized Vlasov-Maxwell equations are used to investigate detailed properties of the transverse electromagnetic Weibel-type instability for a long charge bunch propagating through a cylindrical pipe of radius rw. The kinetic stability analysis is carried out for azimuthally symmetric perturbations about a two-temperature thermal equilibrium distribution in the smooth-focusing approximation. The most unstable modes are identified, and their eigenfrequencies, radial mode structure and instability thresholds are determined. The stability analysis shows that, although there is free energy available to drive the electromagnetic Weibel instability, the finite transverse geometry of the charged particle beam introduces a large threshold value for the temperature anisotropy [(T⊥b/T∥b)Weibel≫(T⊥b/T∥b)Harris] below which the instability is absent. Hence, unlike the case of an electrically neutral plasma, the Weibel instability is not expected to play as significant a role in the process of energy isotropization of intense unneutralized charged particle beams as the electrostatic Harris-type instability.

  13. Boron Particles Agglomeration and Slag Formation During Combustion of Energetic Condensed Systems

    NASA Astrophysics Data System (ADS)

    Meerov, D.; Monogarov, K.; Bragin, A.; Frolov, Yu.; Nikiforova, Anna

    Boron is a promising component of energetic condensed systems due to its high gravimetric heat value, which is significantly higher than that one of aluminum. In the present work, two non-equilibrium processes, i.e., boron particles agglomeration and framework (slag) formation during combustion of high-energy compositions were investigated experimentally. The quench particle collection bomb technique was used to collect the condensed combustion products formed under nitrogen pressures of 0.1 - 4 MPa. The formation of a framework was visualized using high-speed video registration (1200 fps). Particle size, morphology, and surface structure of collected condensed products were evaluated using laser diffractometry and scanning electron microscopy. In the experiments, the weight of the collected condensed combustion products was about 30% of the initial sample weight, where 26% belonged to the products collected from the gas phase and 4% were remained in a highly-porous framework. The initial amorphous boron powder consisted of 1-micron particles, whereas agglomerated particles, which were collected from the gas phase, were 10 μm in diameter. The burning rate of compositions without binder was 4 times higher and the diameter of collected agglomerates was 10 times larger than those for compositions with binder.

  14. A numerical simulation of solar energetic particle dropouts during impulsive events

    SciTech Connect

    Wang, Y.; Qin, G.; Zhang, M.; Dalla, S. E-mail: gqin@spaceweather.ac.cn

    2014-07-10

    This paper investigates the conditions for producing rapid variations of solar energetic particle (SEP) intensity commonly known as 'dropouts'. In particular, we use numerical model simulations based on solving the focused transport equation in the three-dimensional Parker interplanetary magnetic field to put constraints on the properties of particle transport coefficients in both directions perpendicular and parallel to the magnetic field. Our calculations of the temporal intensity profile of 0.5 and 5 MeV protons at the Earth show that the perpendicular diffusion must be small while the parallel mean free path is long in order to reproduce the phenomenon of SEP dropouts. When the parallel mean free path is a fraction of 1 AU and the observer is located at 1 AU, the perpendicular to parallel diffusion ratio must be below 10{sup –5} if we want to see the particle flux dropping by at least several times within 3 hr. When the observer is located at a larger solar radial distance, the perpendicular to parallel diffusion ratio for reproducing the dropouts should be even lower than that in the case of 1 AU distance. A shorter parallel mean free path or a larger radial distance from the source to observer will cause the particles to arrive later, making the effects of perpendicular diffusion more prominent and SEP dropouts disappear. All of these effects require the magnetic turbulence that resonates with the particles to be low everywhere in the inner heliosphere.

  15. Shock Acceleration and Transport of Solar Energetic Particles in the Corona

    NASA Astrophysics Data System (ADS)

    Ng, C. K.; Ko, Y.; Tylka, A. J.; von Rosenvinge, T. T.

    2013-12-01

    In gradual solar energetic particle (SEP) events, the phase-space density of suprathermal seed particles plays an important role in the bootstrap acceleration of SEPs at a coronal-mass-ejection driven shock in the corona. Higher seed proton density causes more rapid resonant amplification of ambient Alfvén waves and hence faster shock acceleration of SEPs. On the other hand, SEP-driven Alfvén wave growth is slowed by higher plasma density and by the thermal damping of left-hand polarized waves at frequencies exceeding a fraction of the proton cyclotron frequency. Damping also influences the background wave distribution. Coronal magnetic field strongly influences the wave-particle interaction since its magnitude scales the resonant wavenumber and its negative parallel gradient focuses the charged particles. The solar-wind velocity and Alfvén speed, relevant to the height of shock formation, are related to the plasma density and magnetic field. Consequently, the spatial dependences of all these environmental parameters influence the coupled evolution of SEP and Alfvén wave distributions. We will present results from our models of SEP acceleration and transport combining the effects of the above physical considerations. The model results will be compared to directly observed and inferred features of SEP events (e.g. streaming-limited intensity, maximum energy, height of first solar particle release) to address the roles and relative importance of the above physical factors.

  16. Toward A More General Technique to Infer Ionic Charge States of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Sollitt, L. S.; Aguirre, E. M.; Briggs, P.

    2011-12-01

    We report on a new method to infer charge states of high energy (≥ 10 MeV/nuc) solar energetic particles. We build on ideas developed in Sollitt (2004) and Sollitt et al. (2008); those papers indicated that in the decay phase of large well-connected solar particle events, particles of different species with the same rigidity (mv/q) exhibit similar decay profiles. Mason et al. (2006) suggested that these similarities extend to overall time-intensity profiles. Our method uses one-hour average particle flux data from the Solar Isotope Spectrometer (SIS) aboard the Advanced Composition Explorer (ACE) spacecraft. We choose a reference species (e.g. Carbon) for which the charge state is known to be stable over a wide range of energies. At each hour we construct a continuous reference energy profile using a cubic spline fit of the flux at the nominal passband energies. Then we best-fit the time profiles of target species (e.g. Iron) to the interpolated time profiles of the reference. Assuming that the matching profiles represent particles of the same rigidity, this analysis generates the ratio of the target species charge to the reference species charge.

  17. Energetic Particle Effects Can Explain the Low Frequency of Alfvin Modes in the DIII-D Tokamak

    SciTech Connect

    Gorelenkov, N.N.; Heidbrink, W.W.

    2001-01-31

    During beam injection in the DIII-D tokamak, modes with lower frequencies than expected for toroidicity-induced Alfvin eigenmodes (TAE) are often observed. We present the analysis of one of these ''beta-induced Alfvin eigenmodes'' (BAE) with a high-n stability code HINST that includes the effect of the energetic ions on the mode frequency. It shows that the ''BAE'' could be the theoretically predicted resonant-TAE (RTAE), which is also called an energetic-particle mode (EPM).

  18. SOLAR ENERGETIC-PARTICLE RELEASE TIMES IN HISTORIC GROUND-LEVEL EVENTS

    SciTech Connect

    Reames, Donald V.

    2009-11-20

    Ground-level events (GLEs) are large solar energetic-particle events with sufficiently hard spectra for GeV protons to be detected by neutron monitors at ground level. For each of 30 well-observed historic GLEs from four solar cycles, extending back to 1973, I have plotted onset times versus velocity{sup -1} for particles observed on the IMP-7 and 8, ISEE-3, Wind, and GOES spacecraft and by neutron monitors. A linear fit on such a plot for each GLE determines the initial solar particle release (SPR) time, as the intercept, and the magnetic path length traversed, as the slope, of the fitted line. Magnetic path lengths and SPR times are well determined by the fits and cannot be used as adjustable parameters to make particle and photon emission times coincide. SPR times follow the onsets of shock-induced type II radio bursts and the coronal height of the coronal mass ejection (CME)-driven shock at SPR time can be determined for GLEs spanning an interval of solar longitude of approx140 deg. For a given GLE, all particle species and energies diverge from a single SPR point at a given coronal height and footpoint longitude of the field line to the Earth. These heights tend to increase with longitudinal distance away from the source, a pattern expected for shock acceleration. Acceleration for magnetically well-connected large GLEs begins at approx2 solar radii, in contrast to non-GLEs that have been found to be strongly associated with shocks above approx3 solar radii. The higher densities and magnetic field strengths at lower altitudes may be responsible for the acceleration of higher-energy particles in GLEs, while those GLEs that begin above 3R {sub S} may compensate by having higher shock speeds. These results support the joint dependence of maximum particle energy on magnetic field strength, injected particle density, and shock speed, all predicted theoretically.

  19. A Study of Interfacial-Instability-Induced Mixing in Explosive Dispersal of Particles

    NASA Astrophysics Data System (ADS)

    Rollin, Bertrand; Annamalai, Subramanian; Ouellet, Frederick

    2015-06-01

    Recent experiments have shown that when a bed of particles is explosively dispersed, a multiphase instability front may occur, and lead to the formation of aerodynamically stable jet-particle structures. It is believed that these coherent structures originates from the early phase of explosive dispersal, in particular, in the manner in which the initial layer of particles undergoes instability, as it rapidly expands in the radial direction. In this work we want to isolate and study the effect of gas-particle two-way interaction on the nature of Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities of an explosively driven particle layer. As a result we perform numerical experiments, where we limit the initial volume fraction of the particle layer. The focus of this investigation is on the RT and RM growth mechanisms in the linear and non-linear stages under the complexity of the cylindrical geometry, very high pressures and densities associated with the detonation process. Thus, in addition to the initial disturbance created by the random distribution of particles, we explicitly vary the initial density of the particle and gas distribution. Detailed analyses of single mode and two-mode RT/RM-induced mixing are presented. This work was supported (in part) by the U.S. DoE, NNSA, ASC Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

  20. Center for Gyrokinetic/MHD Hybrid Simulation of Energetic Particle Physics in Toroidal Plasmas (CSEPP). Final report

    SciTech Connect

    Chen, Yang

    2012-03-07

    At Colorado University-Boulder the primary task is to extend our gyrokinetic Particle-in-Cell simulation of tokamak micro-turbulence and transport to the area of energetic particle physics. We have implemented a gyrokinetic ion/massless fluid electron hybrid model in the global {delta} f-PIC code GEM, and benchmarked the code with analytic results on the thermal ion radiative damping rate of Toroidal Alfven Eigenmodes (TAE) and with mode frequency and spatial structure from eigenmode analysis. We also performed nonlinear simulations of both a single-n mode (n is the toroidal mode number) and multiple-n modes, and in the case of single-n, benchmarked the code on the saturation amplitude vs. particle collision rate with analytical theory. Most simulations use the f method for both ions species, but we have explored the full-f method for energetic particles in cases where the burst amplitude of the excited instabilities is large as to cause significant re-distribution or loss of the energetic particles. We used the hybrid model to study the stability of high-n TAEs in ITER. Our simulations show that the most unstable modes in ITER lie in the rage of 10 < n < 20. Thermal ion pressure effect and alpha particles non-perturbative effect are important in determining the mode radial location and stability threshold. The thermal ion Landau damping rate and radiative damping rate from the simulations are compared with analytical estimates. The thermal ion Landau damping is the dominant damping mechanism. Plasma elongation has a strong stabilizing effect on the alpha driven TAEs. The central alpha particle pressure threshold for the most unstable n=15 mode is about {beta}{sub {alpha}}(0) = 0.7% for the fully shaped ITER equilibrium. We also carried nonlinear simulations of the most unstable n = 15 mode and found that the saturation amplitude for the nominal ITER discharge is too low to cause large redistribution or loss of alpha particles. To include kinetic electron effects

  1. On the Numerical Dispersion of Electromagnetic Particle-In-Cell Code : Finite Grid Instability

    SciTech Connect

    Meyers, Michael David; Huang, Chengkun; Zeng, Yong; Yi, Sunghwan; Albright, Brian James

    2014-07-15

    The Particle-In-Cell (PIC) method is widely used in relativistic particle beam and laser plasma modeling. However, the PIC method exhibits numerical instabilities that can render unphysical simulation results or even destroy the simulation. For electromagnetic relativistic beam and plasma modeling, the most relevant numerical instabilities are the finite grid instability and the numerical Cherenkov instability. We review the numerical dispersion relation of the electromagnetic PIC algorithm to analyze the origin of these instabilities. We rigorously derive the faithful 3D numerical dispersion of the PIC algorithm, and then specialize to the Yee FDTD scheme. In particular, we account for the manner in which the PIC algorithm updates and samples the fields and distribution function. Temporal and spatial phase factors from solving Maxwell's equations on the Yee grid with the leapfrog scheme are also explicitly accounted for. Numerical solutions to the electrostatic-like modes in the 1D dispersion relation for a cold drifting plasma are obtained for parameters of interest. In the succeeding analysis, we investigate how the finite grid instability arises from the interaction of the numerical 1D modes admitted in the system and their aliases. The most significant interaction is due critically to the correct representation of the operators in the dispersion relation. We obtain a simple analytic expression for the peak growth rate due to this interaction.

  2. The 3 January 1978 interplanetary shock event as observed by energetic particle, plasma and magnetic field devices on board of Helios-1, Helios-2 and Prognoz-6

    NASA Astrophysics Data System (ADS)

    Richter, A. K.; Keppler, E.; Rosenbauer, H.; Verigin, M. I.; Gringauts, K. I.; Kurt, V. G.; Stolpovskii, V. G.; Neubauer, F. M.; Gombosi, T.; Somogyi, A.

    The paper investigates different characteristics of the interplanetary medium and of secondary enhancements in the energetic particle fluxes in regions before, at and after a flare generated interplanetary shock wave. The shock exhibits the properties of both an R- and F-type shock event, and the pre-shock intensity enhancements of energetic particles can be explained by a cumulative first-order Fermi acceleration process of successive reflections of the particles at the shock. Post-shock intensity enhancements of energetic particles are due to an acceleration of the particles by the shockwave and/or a trapping of the particles in the downstream region. The energetic particle enhancements at the shock cannot be explained uniquely by the shock drift accleration mechanism, and highly oblique shocks can be accompanied by energetic particle intensity increases.

  3. Colloidal Particles that Rapidly Change Shape via Elastic Instabilities.

    PubMed

    Epstein, Eric; Yoon, Jaewon; Madhukar, Amit; Hsia, K Jimmy; Braun, Paul V

    2015-12-01

    The fabrication and properties of pH-responsive colloidal particles are reported, which change shape rapidly (less than 200 ms), nearly independent of the diffusion of the pH altering species that trigger their actuation, and far more rapid than their Brownian motion. These particles are mechanically bistable, as revealed by their hysteretic shape response. Finite element analysis (FEA) shows that mechanical hysteresis and bistability derives from the colloids' spherical curvature. Mechanical characterization of the bilayered polymers comprising the colloidal particles shows that viscoelastic relaxation plays a non-negligible role in limiting the shape switching rate; however, energy landscapes obtained from FEA simulations suggest that by tuning the elastic moduli and thicknesses of the constituent polymer layers, microparticles of the size shown here may be fabricated to actuate on timescales as fast as 1 μs. PMID:26449185

  4. Energetic particle measurements in the vicinity of Dione during the three Cassini encounters 2005-2011

    NASA Astrophysics Data System (ADS)

    Krupp, N.; Roussos, E.; Kriegel, H.; Kollmann, P.; Kivelson, M. G.; Kotova, A.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Khurana, K. K.

    2013-09-01

    The Cassini spacecraft encountered the moon Dione three times between 2005 and 2011. During the flybys particles and fields measurements have been performed and used to study the magnetospheric interaction between the fourth largest moon in the saturnian system and the surrounding magnetospheric plasma. Here we present the results of the Low Energy Magnetospheric Measurement System (LEMMS), part of the Magnetospheric Imaging Instrument MIMI, measuring energetic ions and electrons above 20 keV up to several MeV and results from the magnetometer instrument (MAG) onboard the spacecraft. The trapped particles in the vicinity of Dione bounce and drift in Saturn’s magnetosphere and eventually are lost onto the surface of the moon. The location and depth of the absorption signature depends on species, their energy and on the geometry of the flyby. Only for the upstream flyby D1 were energy-dependent ion absorption signatures measured and we conclude that protons present in the upstream region can explain the observed dropout features. The other two encounters D2 and D3 went through the moon’s geometrical wake. During each of the encounters we observed absorption signatures in the fluxes of electrons caused by losses of those particles onto the moon during their drift motion in the saturnian magnetosphere. The profile of these absorption signatures is energy dependent, and becomes asymmetric between the planetward and anti-planetward sectors of the moon’s wake at energies above about 100 keV. We compare these electron wake profiles with ones resulting from electron guiding center trajectory tracings in a simulated environment of Dione’s magnetospheric interaction using the “Adaptive hybrid model for space plasma simulations (A.I.K.E.F.)”. Our results indicate that the magnetic and electric field perturbations in Dione’s interaction region, as well as magnetospheric diffusion need to be taken into account in order to explain the features of the energetic

  5. Statistical study of plasma sheet dynamics using ISEE 1 and 2 energetic particle flux data

    SciTech Connect

    Dandouras, J.; Re-grave-accentme, H.; Saint-Marc, A.; Sauvaud, J.A.; Parks, G.K.; Anderson, K.A.; Lin, R.P.

    1986-06-01

    During magnetospheric substorms, satellites embedded in the plasma sheet often detect transient dropouts of plasma and energetic particle fluxes, a phenomemon generally interpreted as indicating the exit of the satellite into the magnetospheric lobe due to a plasma sheet thinning. In order to determine the large-scale dynamics of the near-earth plasma sheet during substorms, three satellite years of ISEE 1 and 2 energetic particle flux data (1.5 and 6 keV), corresponding to 461 particle flux dropouts, have been analyzed. The principal results show that flux dropouts can be observed anywhere in the nightside plasma sheet, independent of the satellite's geocentric distance (for R>12R/sub E/), magnetic local time (except near the magnetospheric flanks) and estimated distance to the neutral sheet. Furthermore, flux dropouts can be observed for any combination of the AE index value and the satellite's distance to the neutral sheet, which shows that the plasma sheet is dynamic even during weak magnetospheric disturbances. Substorms during which the satellites, though situated in the plasma sheet, did not detect any flux dropout, have also been examined, and it is found that the plasma sheet thickness can locally remain unaffected by substorm development for AE index values up to at least 1000 nT. The predictions of the two major plasma sheet thinning models, i.e., the near-tail X-type magnetic neutral line formation model and the MHD rarefaction wave propagation model, are compared to the experimental results, and it is concluded that neither model can account for all of the observations; plasma sheet dynamics are more complex. Phenomenologically, this study suggests that multiple pinching of the plasma sheet and/or large-amplitude three-dimensional plasma sheet oscillations are important in plasma sheet dynamics.

  6. Energetic Fe particle fluence measured in 2002-2004 on the ISS orbit

    NASA Astrophysics Data System (ADS)

    Nymmik, Rikho; Baranov, Dmitrii; Dergachev, Valentin; Panasyuk, Mikhail; Gagarin, Yurii

    PLATAN-M chamber consisting of solid state track detectors was exposed at the outer surface of the ISS during 2002-2004. Fluence of Fe particles (SEPs and GCRs) was measured in the 30-150 MeV/nucleon energy range. Results of the PLATAN-M experiment were compared with the data obtained by the SIS and CRIS instruments (ACE spacecraft). Energy resolution of the PLATAN-M experiment was 3 times better with statistical errors being 2 times lower as compared with the SIS instrument. Spectra measured outside the magnetosphere of the Earth were transformed to the ISS orbit using the model of charged particle penetration to the near-Earth orbit. General coincidence of the results obtained at the two space stations can be seen. Yet some of the SIS energy channels display outliers distant for 6 standard errors from the PLATAN-M spectrum. Comparison of data obtained at the orbital station with measurements carried out in the interplanetary space evidences the reliability of the model describing the transformation of spectra during charged particle penetration inside the magnetosphere. Thus, a broad range of possibilities arises for the study of energetic particles combining the data measured by different instruments both outside and inside the magnetosphere of the Earth.

  7. Double Power Laws in the Event-integrated Solar Energetic Particle Spectrum

    NASA Astrophysics Data System (ADS)

    Zhao, Lulu; Zhang, Ming; Rassoul, Hamid K.

    2016-04-01

    A double power law or a power law with exponential rollover at a few to tens of MeV nucleon‑1 of the event-integrated differential spectra has been reported in many solar energetic particle (SEP) events. The rollover energies per nucleon of different elements correlate with a particle's charge-to-mass ratio (Q/A). The probable causes are suggested as residing in shock finite lifetimes, shock finite sizes, shock geometry, and an adiabatic cooling effect. In this work, we conduct a numerical simulation to investigate a particle's transport process in the inner heliosphere. We solve the focused transport equation using a time-backward Markov stochastic approach. The convection, magnetic focusing, adiabatic cooling effect, and pitch-angle scattering are included. The effects that the interplanetary turbulence imposes on the shape of the resulting SEP spectra are examined. By assuming a pure power-law differential spectrum at the Sun, a perfect double-power-law feature with a break energy ranging from 10 to 120 MeV nucleon‑1 is obtained at 1 au. We found that the double power law of the differential energy spectrum is a robust result of SEP interplanetary propagation. It works for many assumptions of interplanetary turbulence spectra that give various forms of momentum dependence of a particle's mean free path. The different spectral shapes in low-energy and high-energy ends are not just a transition from the convection-dominated propagation to diffusion-dominated propagation.

  8. Energetic-particle-induced electromagnetic geodesic acoustic mode in tokamak plasmas

    SciTech Connect

    Wang, Lingfeng He, Zhixiong; He, Hongda; Shen, Y.; Dong, J. Q.

    2014-07-15

    Energetic-particle-induced kinetic electromagnetic geodesic acoustic modes (EKEGAMs) are numerically studied in low β (=plasma pressure/magnetic pressure) tokamak plasmas. The parallel component of the perturbed vector potential is considered along with the electrostatic potential perturbation. The effects of finite Larmor radius and finite orbit width of the bulk and energetic ions as well as electron parallel dynamics are all taken into account in the dispersion relation. Systematic harmonic and ordering analysis are performed for frequency and growth rate spectra of the EKEGAMs, assuming (kρ{sub i})∼q{sup −3}∼β≪1, where q, k, and ρ{sub i} are the safety factor, radial component of the EKEGAMs wave vector, and the Larmor radius of the ions, respectively. It is found that there exist critical β{sub h}/β{sub i} values, which depend, in particular, on pitch angle of energetic ions and safety factor, for the mode to be driven unstable. The EKEGAMs may also be unstable for pitch angle λ{sub 0}B<0.4 in certain parameter regions. Finite β effect of the bulk ions is shown to have damping effect on the EKEGAMs. Modes with higher radial wave vectors have higher growth rates. The damping from electron dynamics is found decreasing with decrease of the temperature ratio T{sub e}/T{sub i}. The modes are easily to be driven unstable in low safety factor q region and high temperature ratio T{sub h}/T{sub i} region. The harmonic features of the EKEGAMs are discussed as well.

  9. Modification of Particle Distributions By MHD Instabilities I

    SciTech Connect

    R.B. White

    2010-12-23

    The modification of particle distributions by low amplitude magnetohydrodynamic modes is an important topic for magnetically confined plasmas. Low amplitude modes are known to be capable of producing significant modification of injected neutral beam profiles, and the same can be expected in burning plasmas for the alpha particle distributions. Flattening of a distribution due to phase mixing in an island or due to portions of phase space becoming stochastic is a process extremely rapid on the time scale of an experiment but still very long compared to the time scale of guiding center simulations. Thus it is very valuable to be able to locate significant resonances and to predict the final particle distribution produced by a given spectrum of magnetohydrodynamic modes. In this paper we introduce a new method of determining domains of phase space in which good surfaces do not exist and use this method for quickly determining the final state of the particle distribution without carrying out the full time evolution leading to it.

  10. Simulating the frontal instability of lock-exchange density currents with dissipative particle dynamics

    NASA Astrophysics Data System (ADS)

    Li, Yanggui; Geng, Xingguo; Wang, Heping; Zhuang, Xin; Ouyang, Jie

    2016-06-01

    The frontal instability of lock-exchange density currents is numerically investigated using dissipative particle dynamics (DPD) at the mesoscopic particle level. For modeling two-phase flow, the “color” repulsion model is adopted to describe binary fluids according to Rothman-Keller method. The present DPD simulation can reproduce the flow phenomena of lock-exchange density currents, including the lobe-and-cleft instability that appears at the head, as well as the formation of coherent billow structures at the interface behind the head due to the growth of Kelvin-Helmholtz instability. Furthermore, through the DPD simulation, some small-scale characteristics can be observed, which are difficult to be captured in macroscopic simulation and experiment.

  11. Nonmodal instability of a stratified plane-channel suspension flow with fine particles.

    PubMed

    Boronin, Sergei A; Osiptsov, Alexander N

    2016-03-01

    We consider the nonmodal instability and transient growth of small disturbances in a plane-channel suspension flow with a nonuniform concentration profile of fine noncolloidal particles accumulated in two localized layers, symmetric about the channel axis. A single-velocity model of an effective Newtonian fluid with a finite particle volume fraction is employed. It is established that fine particles distributed nonuniformly in the main flow significantly modify the growth rate of the first mode in a wide range of governing parameters. The most pronounced destabilizing effect is produced by the particles localized in the vicinity of the walls. A parametric study of the so-called optimal disturbances showed that they are streaks elongated in the flow direction, similar to the optimal disturbances in the flow devoid of particles. The transverse wave number of the optimal disturbances depends strongly on the location of the particle layers. Even when the particle mass concentration (averaged over the channel cross section) is small (of the order of a percent) and the particles are localized in the middle between the walls and the channel axis, the energy of the optimal disturbances is by several orders of magnitude larger than in dusty-gas and pure-fluid flows. When the particle layers are located in the vicinity of the walls or the channel axis, the nonmodal instability mechanism is less pronounced, as compared to the flow devoid of particles. PMID:27078447

  12. Feedback control of plasma instabilities with charged particle beams and study of plasma turbulence

    NASA Technical Reports Server (NTRS)

    Tham, Philip Kin-Wah

    1994-01-01

    A new non-perturbing technique for feedback control of plasma instabilities has been developed in the Columbia Linear Machine (CLM). The feedback control scheme involves the injection of a feedback modulated ion beam as a remote suppressor. The ion beam was obtained from a compact ion beam source which was developed for this purpose. A Langmuir probe was used as the feedback sensor. The feedback controller consisted of a phase-shifter and amplifiers. This technique was demonstrated by stabilizing various plasma instabilities to the background noise level, like the trapped particle instability, the ExB instability and the ion-temperature-gradient (ITG) driven instability. An important feature of this scheme is that the injected ion beam is non-perturbing to the plasma equilibrium parameters. The robustness of this feedback stabilization scheme was also investigated. The principal result is that the scheme is fairly robust, tolerating about 100% variation about the nominal parameter values. Next, this scheme is extended to the unsolved general problem of controlling multimode plasma instabilities simultaneously with a single sensor-suppressor pair. A single sensor-suppressor pair of feedback probes is desirable to reduce the perturbation caused by the probes. Two plasma instabilities the ExB and the ITG modes, were simultaneously stabilized. A simple 'state' feedback type method was used where more state information was generated from the single sensor Langmuir probe by appropriate signal processing, in this case, by differentiation. This proof-of-principle experiment demonstrated for the first time that by designing a more sophisticated electronic feedback controller, many plasma instabilities may be simultaneously controlled. Simple theoretical models showed generally good agreement with the feedback experimental results. On a parallel research front, a better understanding of the saturated state of a plasma instability was sought partly with the help of feedback

  13. Modeling Extreme Solar Energetic Particle Acceleration with Self-Consistent Wave Generation

    NASA Astrophysics Data System (ADS)

    Arthur, A. D.; le Roux, J. A.

    2015-12-01

    Observations of extreme solar energetic particle (SEP) events associated with coronal mass ejection driven shocks have detected particle energies up to a few GeV at 1 AU within the first ~10 minutes to 1 hour of shock acceleration. Whether or not acceleration by a single shock is sufficient in these events or if some combination of multiple shocks or solar flares is required is currently not well understood. Furthermore, the observed onset times of the extreme SEP events place the shock in the corona when the particles escape upstream. We have updated our focused transport theory model that has successfully been applied to the termination shock and traveling interplanetary shocks in the past to investigate extreme SEP acceleration in the solar corona. This model solves the time-dependent Focused Transport Equation including particle preheating due to the cross shock electric field and the divergence, adiabatic compression, and acceleration of the solar wind flow. Diffusive shock acceleration of SEPs is included via the first-order Fermi mechanism for parallel shocks. To investigate the effects of the solar corona on the acceleration of SEPs, we have included an empirical model for the plasma number density, temperature, and velocity. The shock acceleration process becomes highly time-dependent due to the rapid variation of these coronal properties with heliocentric distance. Additionally, particle interaction with MHD wave turbulence is modeled in terms of gyroresonant interactions with parallel propagating Alfven waves. However, previous modeling efforts suggest that the background amplitude of the solar wind turbulence is not sufficient to accelerate SEPs to extreme energies over the short time scales observed. To account for this, we have included the transport and self-consistent amplification of MHD waves by the SEPs through wave-particle gyroresonance. We will present the results of this extended model for a single fast quasi-parallel CME driven shock in the

  14. The Energetic Particles: Acceleration, Composition, and Transport (EPACT) investigation on the WIND spacecraft

    NASA Astrophysics Data System (ADS)

    von Rosenvinge, T. T.; Barbier, L. M.; Karsch, J.; Liberman, R.; Madden, M. P.; Nolan, T.; Reames, D. V.; Ryan, L.; Singh, S.; Trexel, H.; Winkert, G.; Mason, G. M.; Hamilton, D. C.; Walpole, P.

    1995-02-01

    The Energetic Particles: Acceleration, Composition, and Transport (EPACT) investigation is designed to make comprehensive observations of solar, interplanetary, and galactic particles over wide ranges of charge, mass, energy, and intensity using a combination of 8 different particle telescopes. This paper summarizes the scientific goals of EPACT and provides a detailed description of the instrument design and capabilities. Electrons are measured from 0.2 to 10 MeV, primarily providing time markers for injections of solar particles. Hydrogen is measured from 1.4 to 120 MeV, and Helium is measured from 0.04 to 500 MeV nucl-1. The collection powers and energy ranges for heavier nuclei up to iron are ideal for observations of quiet-time populations such as particles accelerated by interplanetary shocks and the anomalous cosmic rays (thought to be accelerated at the boundary of the heliosphere). The large collection power available is also ideal for observations of3He,4He, and heavier nuclei in impulsive3He-rich solar events. There is even the possibility of observing ultra heavy nuclei (Z>30) in large solar events for the first time. Finally, there is a telescope designed to measure isotopes from He (3.4 55 MeV nucl-1) to Fe (12 230 MeV nucl-1), which is intended for solar particles, the anomalous cosmic rays and galactic cosmic rays. The overall capabilities of EPACT provide scientifically interesting measurements over all phases of the solar cycle. There will also be important opportunities for combined studies with other spacecraft, such as SAMPEX, Ulysses, and Voyagers 1 and 2.

  15. Asymmetry of the Mars Ionosphere Boundary Altitude during a Solar Energetic Particle Event

    NASA Astrophysics Data System (ADS)

    Frahm, R. A.; Elliott, H. A.; Winningham, J. D.; Sharber, J. R.; DeForest, C. E.; Howard, T. A.; Kallio, E. J.; McKenna-Lawlor, S.; Duru, F.; Morgan, D. D.; Coates, A. J.; Odstrcil, D.; Lundin, R. N.; Futaana, Y.; Barabash, S. V.

    2013-12-01

    The Electron Spectrometer (ELS) and the Ion Mass Spectrometer (IMA) from the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the ESA's Mars Express (MEx) spacecraft have been used to study a Solar Energetic Particle (SEP) event associated with a Class X solar flare on on January 27, 2012. Arrival of the SEP at Mars about 46 minutes later is observed as an increase in the background of these plasma instruments. The background counts were observed to increase sharply, followed by a gradual decrease that lasted for about 4 days. During this time, ELS and IMA also recorded passages across the Martian ionospheric boundary on the dusk side of the planet, twice during each MEx orbit. The altitude of the ionospheric boundary was thereby found to have behaved differently in the northern and southern hemispheres. The boundary increased in altitude in each hemisphere with a time delay as the flare pumped energy into the Mars system. After reaching peak altitude, the ionospheric boundary returned to its original configuration faster in the northern than in the southern hemisphere. This suggests that the main difference between the northern and southern hemispheres at Mars, namely the presence in the south of crustal magnetic fields, is responsible for the dissipation of the energy input at a slower rate in the southern than in the northern hemisphere.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  17. Modification of Shear Alfvén Spectral Gaps by Energetic Particles

    NASA Astrophysics Data System (ADS)

    van Dam, J. W.; Wong, H. V.; Fredrickson, E. D.; Chang, Z.; Fu, G. Y.

    1997-11-01

    The presence of a highly energetic, trapped ion population in a tokamak plasma is able to broaden the width of the forbidden frequency gaps in the shear Alfvén spectrum. This new effect is in addition to, and sometimes exceeds in magnitude, the usual geometrical effects such as toroidicity or noncircularity. This theory is applied to interpret recent observations, in the TFTR tokamak, of Alfvén waves whose frequency is approximately twice that for the usual toroidicity-induced Alfvén eigenmode (TAE) and which appear to be resonantly excited by minority fast ions created by off-axis ion cyclotron wave heating. A key point is that although the TFTR cross section has no elongation, the energetic particles may be able to open up the gap corresponding to the ellipticity-induced Alfvén eigenmode (EAE). Experimentally, these "twice-TAE" fluctuations are not observed with on-axis or low-field-side ICRF heating. Work performed at IFS under US DoE Contract No. DE-FG03-96ER54346 and at PPPL under US DoE Contract No. DE-AC02-76-CHO-3073.

  18. WAITING TIME DISTRIBUTION OF SOLAR ENERGETIC PARTICLE EVENTS MODELED WITH A NON-STATIONARY POISSON PROCESS

    SciTech Connect

    Li, C.; Su, W.; Fang, C.; Zhong, S. J.; Wang, L.

    2014-09-10

    We present a study of the waiting time distributions (WTDs) of solar energetic particle (SEP) events observed with the spacecraft WIND and GOES. The WTDs of both solar electron events (SEEs) and solar proton events (SPEs) display a power-law tail of ∼Δt {sup –γ}. The SEEs display a broken power-law WTD. The power-law index is γ{sub 1} = 0.99 for the short waiting times (<70 hr) and γ{sub 2} = 1.92 for large waiting times (>100 hr). The break of the WTD of SEEs is probably due to the modulation of the corotating interaction regions. The power-law index, γ ∼ 1.82, is derived for the WTD of the SPEs which is consistent with the WTD of type II radio bursts, indicating a close relationship between the shock wave and the production of energetic protons. The WTDs of SEP events can be modeled with a non-stationary Poisson process, which was proposed to understand the waiting time statistics of solar flares. We generalize the method and find that, if the SEP event rate λ = 1/Δt varies as the time distribution of event rate f(λ) = Aλ{sup –α}exp (– βλ), the time-dependent Poisson distribution can produce a power-law tail WTD of ∼Δt {sup α} {sup –3}, where 0 ≤ α < 2.

  19. A Statistical Study of Spectral Hardening in Solar Flares and Related Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Grayson, J.; Krucker, S.; Lin, R. P.

    2009-12-01

    Using hard X-ray observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we investigate the reliability of spectral hardening during solar flares as an indicator of related solar energetic particle (SEP) events at Earth. All RHESSI data are analyzed, from February 2002 through the end of Solar Cycle 23, thereby expanding upon recent work on a smaller sample of flares. Previous investigations have found very high success when associating soft-hard-harder (SHH) spectral behavior with energetic proton events, and confirmation of this link would suggest a correlation between electron acceleration in solar flares and SEPs seen in interplanetary space. In agreement with these past findings, we find that of 37 magnetically well-connected flares (W30-W90), 12 of 18 flares with SHH behavior produced SEP events and none of 19 flares without SHH behavior produced SEPs. This demonstrates a statistically significant dependence of SHH and SEP observations, a link that is unexplained in the standard scenario of SEP acceleration at the shock front of coronal mass ejections, and encourages further investigation of the mechanisms which could be responsible.

  20. A Statistical Study of Spectral Hardening in Solar Flares and Related Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Grayson, James A.; Krucker, Säm; Lin, R. P.

    2009-12-01

    Using hard X-ray observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we investigate the reliability of spectral hardening during solar flares as an indicator of related solar energetic particle (SEP) events at Earth. All RHESSI data are analyzed, from 2002 February through the end of Solar Cycle 23, thereby expanding upon recent work on a smaller sample of flares. Previous investigations have found very high success when associating soft-hard-harder (SHH) spectral behavior with energetic proton events, and confirmation of this link would suggest a correlation between electron acceleration in solar flares and SEPs seen in interplanetary space. In agreement with these past findings, we find that of 37 magnetically well-connected flares (W30-W90), 12 of 18 flares with SHH behavior produced SEP events and none of 19 flares without SHH behavior produced SEPs. This demonstrates a statistically significant dependence of SHH and SEP observations, a link that is unexplained in the standard scenario of SEP acceleration at the shock front of coronal mass ejections and encourages further investigation of the mechanisms which could be responsible.