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Sample records for energetic particle instability

  1. Alfven instabilities effects on energetic particles

    SciTech Connect

    Zonca, F.; Briguglio, S.; Fogaccia, G.; Vlad, G.

    1999-09-20

    In the present work, a review of shear Alfven instabilities effects on energetic particles is presented and important results of both theory and experiments are emphasized. Open problems and possible topics for future discussions are also indicated, such as those related to the observation of 'frequency chirping modes' associated with fast minority ion tails produced during ICRF heating on TFTR, which may be interpreted as Energetic Particle Modes (EPM)

  2. Particle-in-Cell simulation of energetic particles driven instabilities

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Parker, Scott E.; Lang, Jianying; Fu, Guoyong

    2009-11-01

    We present simulations of the evolution of energetic particles driven modes with the gyrokinetic turbulence code GEMfootnotetextY. Chen and S. E. Parker, J. Comp. Phys. 220, 839 (2007), except that kinetic electrons are replaced by a mass-less fluid model. PIC simulations of energetic particles use either the conventional full-f method or the δ method. The latter is adequate for low-amplitude fluctuation amplitudes. The collisional δ -methodfootnotetextY. Chen and R. White, Phys. Plasmas 4, 3591 (1997) is used to systematically account for collisions and particle source and sink. Steady state saturation amplitudes are benchmarked with predictions of analytic theory. We also employ full-f simulationsfootnotetextY. Todo et. al, Phys. Plasmas 10, 2888 (2003) to study bursty events in which the instabilities reach large amplitudes and cause macroscopic redistribution or loss of the particles. With full-f it is easy to retain all the nonlinear effects and treat accurately discontinuities in the distribution function at phase-space boundaries. Whereas the energetic particle current is neglegible in the Ampere's law in δ simulations, it is important in full-f simulations. Thermal ion kinetic effects are observed to be important.

  3. Magnetohydrodynamic ballooning instabilities excited by energetic trapped particles

    SciTech Connect

    Weiland, J.; Chen, L.

    1984-09-01

    A new branch of magnetohydrodynamic ballooning modes is shown to be destabilized by energetic trapped particles. Both the real frequencies and growth rates of the instabilities are comparable to the trapped-particle precession frequencies. The theoretical results are also shown to be consistent with the high-frequency (approx. 100 kHz) oscillations observed during the high-power beam-injection experiments in PDX.

  4. Theory of magnetohydrodynamic instabilities excited by energetic particles in tokamaks

    SciTech Connect

    Chen, L. )

    1994-07-20

    The resonant excitations of high-n magnetohydrodynamic (MHD) instabilities by the energetic ions/alpha particles in tokamaks are theoretically analyzed. Here, n is the toroidal mode number. Since, typically, the MHD modes consist of two-scale structures; one singular ( inertial'') region and one regular (ideal) region, the energetic particle contributions in the singular region are suppressed by the finite-size orbits. Analytical dispersion relations can then be derived via the asymptotic matching analysis. The dispersion relations have the generic form of the fishbone'' dispersion relation and demonstrate, in particular, the existence of two types of modes; that is, the MHD gap mode and the energetic-particle continuum mode. Specific expressions are given for both the kinetic ballooning modes (KBM) and the toroidal Alfven modes (TAM). It is suggested that the stability property may be qualitatively regarded as the hybrid'' of conventional MHD tokamaks and field reversed ion rings. [copyright]American Institute of Physics

  5. Theory of magnetohydrodynamic instabilities excited by energetic particles in tokamaks

    SciTech Connect

    Chen, L. )

    1994-05-01

    The resonant excitations of high-[ital n] magnetohydrodynamic instabilities by the energetic ions/alpha particles in tokamaks are theoretically analyzed. Here, [ital n] is the toroidal mode number. The magnetohydrodynamic eigenmodes, typically, consist of two-scale structures; one corresponds to the singular ( inertial'') region and the other the regular (ideal) region. Due to the finite-size orbits, the energetic particle contributions in the singular region are suppressed. Analytical dispersion relations can be derived via the asymptotic matching analysis. The dispersion relations have the generic form of the fishbone'' dispersion relation [Phys. Rev. Lett. [bold 52], 1122 (1984)] and demonstrate, in particular, the existence of two types of modes; that is, the discrete gap mode and the energetic-particle continuum mode. Specific expressions are given for both the kinetic ballooning modes and the toroidal Alfven modes.

  6. 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.

  7. Suppression of energetic particle driven instabilities with HHFW heating

    NASA Astrophysics Data System (ADS)

    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 2000 Nucl. Fusion 40 557) heated with neutral beams, the beam ions typically excite energetic particle modes (or fishbones), and toroidal, global or compressional Alfvén eigenmodes. 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.

  8. Suppression of energetic particle driven instabilities with HHFW heating

    DOE PAGES

    Fredrickson, E. D.; Taylor, G.; Bertelli, N.; ...

    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

  9. 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.

  10. 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

  11. Multi-phase hybrid simulation of energetic particle driven magnetohydrodynamic instabilities in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Todo, Y.

    2016-11-01

    Magnetohydrodynamic (MHD) instabilities driven by energetic particles in tokamak plasmas and the energetic particle distribution formed with the instabilities, neutral beam injection, and collisions are investigated with hybrid simulations for energetic particles and an MHD fluid. The multi-phase simulation, which is a combination of classical simulation and hybrid simulation, is applied to examine the distribution formation process in the collisional slowing-down time scale of energetic ions for various beam deposition power ({P}{NBI}) and slowing-down time ({τ }{{s}}). The physical parameters other than {P}{NBI} and {τ }{{s}} are similar to those of a Tokamak Fusion Test Reactor (TFTR) experiment (Wong et al 1991 Phys. Rev. Lett. 66 1874). For {P}{NBI} = 10 MW and {τ }{{s}} = 100 ms, which is similar to the TFTR experiment, the bursts of toroidal Alfvén eigenmodes take place with a time interval 2 ms, which is close to that observed in the experiment. The maximum radial velocity amplitude (v r) of the dominant TAE at the bursts in the simulation is {v}{{r}}/{v}{{A}}∼ 3× {10}-3 where v A is the Alfvén velocity at the plasma center. For {P}{NBI} = 5 MW and {τ }{{s}} = 20 ms, the amplitude of the dominant TAE is kept at a constant level {v}{{r}}/{v}{{A}}∼ 4× {10}-4. The intermittency of TAE rises with increasing {P}{NBI} and increasing {τ }{{s}} (= decreasing collision frequency). With increasing volume-averaged classical energetic ion pressure, which is well proportional to {P}{NBI}{τ }{{s}}, the energetic ion confinement degrades monotonically due to the transport by the instabilities. The volume-averaged energetic ion pressure depends only on the volume-averaged classical energetic ion pressure, not independently on {P}{NBI} or {τ }{{s}}. The energetic ion pressure profile resiliency, where the increase in energetic ion pressure profile is saturated, is found for the cases with the highest {P}{NBI}{τ }{{s}} where the TAE bursts take place.

  12. Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator

    NASA Astrophysics Data System (ADS)

    Spong, D. A.; Holod, I.; Todo, Y.; Osakabe, M.

    2017-08-01

    Energetic particles are inherent to toroidal fusion systems and can drive instabilities in the Alfvén frequency range, leading to decreased heating efficiency, high heat fluxes on plasma-facing components, and decreased ignition margin. The applicability of global gyrokinetic simulation methods to macroscopic instabilities has now been demonstrated and it is natural to extend these methods to 3D configurations such as stellarators, tokamaks with 3D coils and reversed field pinch helical states. This has been achieved by coupling the GTC global gyrokinetic PIC model to the VMEC equilibrium model, including 3D effects in the field solvers and particle push. This paper demonstrates the application of this new capability to the linearized analysis of Alfvénic instabilities in the LHD stellarator. For normal shear iota profiles, toroidal Alfvén instabilities in the n  =  1 and 2 toroidal mode families are unstable with frequencies in the 75 to 110 kHz range. Also, an LHD case with non-monotonic shear is considered, indicating reductions in growth rate for the same energetic particle drive. Since 3D magnetic fields will be present to some extent in all fusion devices, the extension of gyrokinetic models to 3D configurations is an important step for the simulation of future fusion systems. ).

  13. Global linear gyrokinetic simulation of energetic particle-driven instabilities in the LHD stellarator

    DOE PAGES

    Spong, Donald A.; Holod, Ihor; Todo, Y.; ...

    2017-06-23

    Energetic particles are inherent to toroidal fusion systems and can drive instabilities in the Alfvén frequency range, leading to decreased heating efficiency, high heat fluxes on plasma-facing components, and decreased ignition margin. The applicability of global gyrokinetic simulation methods to macroscopic instabilities has now been demonstrated and it is natural to extend these methods to 3D configurations such as stellarators, tokamaks with 3D coils and reversed field pinch helical states. This has been achieved by coupling the GTC global gyrokinetic PIC model to the VMEC equilibrium model, including 3D effects in the field solvers and particle push. Here, this papermore » demonstrates the application of this new capability to the linearized analysis of Alfvénic instabilities in the LHD stellarator. For normal shear iota profiles, toroidal Alfvén instabilities in the n = 1 and 2 toroidal mode families are unstable with frequencies in the 75 to 110 kHz range. Also, an LHD case with non-monotonic shear is considered, indicating reductions in growth rate for the same energetic particle drive. Finally, since 3D magnetic fields will be present to some extent in all fusion devices, the extension of gyrokinetic models to 3D configurations is an important step for the simulation of future fusion systems.« less

  14. Effects of energetic particle phase space modifications by instabilities on integrated modeling

    NASA Astrophysics Data System (ADS)

    Podestà, M.; Gorelenkova, M.; Fredrickson, E. D.; Gorelenkov, N. N.; White, R. B.

    2016-11-01

    Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long time-scale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work to investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NB-heated NSTX and DIII-D discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NB-driven current profile and NB power transferred to the thermal plasma species. Those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.

  15. Effects of energetic particle phase space modifications by instabilities on integrated modeling

    DOE PAGES

    Podesta, M.; Gorelenkova, M.; Fredrickson, E. D.; ...

    2016-07-22

    Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effectivemore » tool for long time-scale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work to investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NB-heated NSTX and DIII-D discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NB-driven current profile and NB power transferred to the thermal plasma species. Furthermore, those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.« less

  16. Effects of energetic particle phase space modifications by instabilities on integrated modeling

    SciTech Connect

    Podesta, M.; Gorelenkova, M.; Fredrickson, E. D.; Gorelenkov, N. N.; White, R. B.

    2016-07-22

    Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long time-scale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work to investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NB-heated NSTX and DIII-D discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NB-driven current profile and NB power transferred to the thermal plasma species. Furthermore, those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.

  17. Effects of energetic particle phase space modifications by instabilities on integrated modeling

    SciTech Connect

    Podesta, M.; Gorelenkova, M.; Fredrickson, E. D.; Gorelenkov, N. N.; White, R. B.

    2016-07-22

    Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long time-scale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work to investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NB-heated NSTX and DIII-D discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NB-driven current profile and NB power transferred to the thermal plasma species. Furthermore, those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.

  18. Energetic particle effects on n=1 MHD instabilities in a DIII-D hybrid discharge

    NASA Astrophysics Data System (ADS)

    Brennan, D. P.; Halfmoon, M. R.; Kim, C. C.; La Haye, R. J.

    2012-03-01

    The δf kinetic-MHD model in the 3-D extended MHD code NIMROD is used to perform a simulation study of energetic particle effects on the n=1 mode in a DIII-D hybrid discharge. The hybrid has low qmin>˜1 at high confinement, and is a candidate operational scenario for burning plasma experiments. However hybrid discharges are limited to moderate βN by the m/n=2/1 instability. Using realistic DIII-D equilibria, the stability of the n=1 mode is computed over a (qmin,βN) space. Unstable modes are driven by energetic particles far into the MHD stable region in this space. The drive is associated with the fishbone mode or BAE mode, depending on qmin. The stability boundary is found near the experimental (qmin,βN), where the unstable mode has a m/n=1/1 component localized near the axis. Experimentally, a m/n=1/1 structure is observed in agreement with the computed mode in key physical respects. At higher qmin and βN a mode with a broad m/n=2/1 structure is unstable. This suggests that the m/n=2/1 mode is triggered by energetic particles in these discharges, as βN is increased. A group of several similar discharges shows strong agreement with this computational explanation of onset.

  19. Nonlinear interplay of Alfvén instabilities and energetic particles in tokamaks

    NASA Astrophysics Data System (ADS)

    Biancalani, A.; Bottino, A.; Cole, M.; Di Troia, C.; Lauber, Ph; Mishchenko, A.; Scott, B.; Zonca, F.

    2017-05-01

    The confinement of energetic particles (EPs) is crucial in the efficient heating of tokamak plasmas. Plasma instabilities such as Alfvén eigenmodes (AEs) can redistribute the EP population, making the plasma heating less effective and leading to additional loads on the walls. The nonlinear dynamics of toroidicity induced AEs (TAEs) is investigated by means of the global gyrokinetic particle-in-cell code ORB5, within the NEMORB project. The nonperturbative nonlinear interplay of TAEs and EPs due to the wave-particle nonlinearity is studied. In particular, we focus on the linear modification of the frequency, growth rate and radial structure of the TAE, caused by the nonlinear evolution of the EP distribution function. For the ITPA benchmark case, we find that the frequency increases when the growth rate decreases, and the mode shrinks radially. The theoretical interpretation is given in terms of a nonperturbative nonlinear evolution of the AE in relation to the Alfvén continuum.

  20. 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.

  1. 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.

  2. Alfv'en instabilities and energetic particle physics in toroidal plasmas

    NASA Astrophysics Data System (ADS)

    Spong, Donald

    2012-03-01

    Modeling capabilities and experimental diagnostics for energetic particle-driven Alfv'en instabilities have advanced significantly in recent years. Simulation tools now range from rapidly applied reduced-dimensionality models and hybrid fluid particle models to more comprehensive gyrokinetic approaches. Alfv'en mode theory has been applied not only to tokamaks, but also to stellarators and reversed field pinches. Current diagnostic techniques allow direct imaging of the mode structure, fast ion density and loss patterns at the plasma edge, allowing theory/experiment comparisons in greater depth than previously possible. Examples from a variety of tokamak, stellarator and reversed field pinch experiments and the associated theory will be described. These activities are preparing the way for future ignited devices, such as ITER, where energetic alpha particles will provide the dominant plasma heating mechanism. High fidelity models of alpha behavior will be required for predicting their effects on the alpha heating profile, non-diffusive transport, nonlinear feedback loops and localized wall heat loads; in addition, understanding Alfv'en spectral emissions can provide diagnostic opportunities. Projections of the current models to ITER and future physics needs will be discussed.

  3. Stabilization of the resistive wall mode instability by trapped energetic particles

    SciTech Connect

    Hao, G. Z.; Wang, A. K.; Jiang, H. B.; Lu, Gaimin; He, H. D.; Qiu, X. M.; Liu, Y. Q.

    2011-03-15

    A theoretical model for investigating the effect of the trapped energetic particles (EPs) on the resistive wall mode (RWM) instability is proposed. The results demonstrate that the trapped EPs have a dramatic stabilizing effect on the RWM because of resonant interaction between the mode and the magnetic precession drift motion of the trapped EPs. The results also show that the effect of the trapped EPs depends on the wall position. In addition, the stabilizing effect becomes stronger when the plasma rotation is taken into account. For sufficiently fast plasma rotation, the trapped EPs can lead to the complete stabilization of the RWM. Furthermore, the trapped EPs can induce a finite real frequency of the RWM in the absence of plasma rotation.

  4. Alfvén instabilities and energetic particle physics in stellarators

    NASA Astrophysics Data System (ADS)

    Spong, Don

    2011-10-01

    Stellarators, helical RFPs and 3D tokamaks introduce symmetry-breaking effects that alter the structure of Alfvén instabilities and their impact on energetic particle confinement. Loss of symmetry precludes an ignorable coordinate and requires taking into account both poloidal and toroidal couplings. New techniques for near term progress in 3D EP modeling have been developed, such as scalable algorithms (e.g., perturbative particle methods and windowed frequency solvers) and reduced-dimensionality models (e.g., gyro-Landau fluid). These methods have been developed for a range of 3D (tokamak/stellarator/RFP) configurations and have been compared with experimental measurements on LHD, TJ-II, HSX and RFX. Both modes with weak 3D couplings (TAE's in LHD) and strong 3D couplings (HAE's in TJ-II) will be discussed. Also, code-benchmarking activities have been started and will be described. In addition to their impact on fast ion confinement, the coherent frequencies of these AE modes (directly related to iota) can be useful markers for 3D equilibrium reconstruction. Research sponsored by the U.S. Department of Energy under Contract DE-AC05-00OR22725 with UT-Battelle, LLC.

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

    NASA Astrophysics Data System (ADS)

    Lin, Liang

    2013-10-01

    Multiple bursty energetic-particle (EP) modes with fishbone-like structures are observed during 1 MW tangential neutral-beam injection into MST reversed field pinch (RFP) plasmas. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to large fast ion beta and stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of these instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport and interaction with global tearing modes. Internal magnetic field fluctuations associated with the EP modes are directly observed for the first time by Faraday-effect polarimetry (frequency ~ 90 kHz and amplitude ~ 2 G). Simultaneously measured density fluctuations exhibit a dynamically evolving and asymmetric spatial structure that peaks near the core where fast ions reside and shifts outward as the instability evolves. Furthermore, the EP mode frequencies appear at ~k∥VA , consistent with continuum modes destabilized by strong drive. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growing phase arising from the beam fueling followed by a rapid drop (~ 15 %) when the EP modes peak, indicating the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced (× 2) with the onset of multiple nonlinearly-interacting EP modes. The fast ions also impact global tearing modes, reducing their amplitudes by up to 65%. This mode reduction is lessened following the EP-bursts, further evidence for fast ion redistribution that weakens the suppression mechanism. Possible tearing mode suppression mechanisms will be discussed. Work supported by US DoE.

  6. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pincha)

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 (qfi) 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.

  7. 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.

  8. Global hybrid simulations of energetic particle effects on the n=1 mode in tokamaks: Internal kink and fishbone instability

    SciTech Connect

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

    2006-05-15

    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.

  9. 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.

  10. Energetic-Particle-Driven Instabilities and Their Effect on Fast Ions in a Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, W. X.; Brower, D. L.; Koliner, J. J.; Eilerman, S.; Reusch, J.; Anderson, J. K.; Almagri, A. F.; Chapman, B. E.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Liu, D.

    2012-10-01

    During 1 MW tangential neutral-beam injection (NBI) into the MST reversed field pinch, multiple, bursty instabilities (n=5, 4 and -1) are detected by various fluctuation diagnostics. The spatial structure of associated density fluctuations peaks near the core where fast ions reside. Significant bicoherence among them is measured, indicating nonlinear three-wave coupling. These instabilities are also observed by a laser-based Faraday-rotation diagnostic, containing critical information on the internal magnetic field fluctuations. A tangential-view high-energy neutral particle analyzer (NPA) is used to study the fast-ion population. The measured NPA signal decreases by 15% following NBI-driven instabilities, indicating fluctuation-induced fast-ion transport. The NBI also reduces the amplitude of the innermost-resonant tearing mode by up to 65%. This mode-suppression is lessened following the NBI-driven bursts, consistent with fast ion loss/redistribution weakening the suppression effect.

  11. Alfvén Instabilities Excited by Energetic Particles in a Parameter Regime Similar to EAST Operation

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Chundong; Hu, Shuanghui; Wu, Bin; Ding, Siye

    2013-08-01

    The kinetic excitation of ideal magnetohydrodynamic (MHD) Alfvén instabilities is investigated for operations at the EAST tokamak. The instabilities include α-induced toroidal Alfvén eigenmodes (αTAE here, α = -q2Rdβ/dr, with q being the safety factor, β the ratio between the plasma and magnetic pressures, R the major radius, and r the minor radius), toroidicity-induced Alfvén eigenmodes (TAE), and the energetic particle continuum mode (EPM). The αTAE, trapped by α-induced potential wells along the magnetic field line, can be readily destabilized by energetic particles due to negligible continuum damping via wave energy tunneling. It is shown for the geometry and the parameters similar to those of the EAST equilibrium that αTAE is different not only from the EPM by the potential-well determined frequency, but also from the TAE by the broad frequency spectrum outside the toroidal frequency gap.

  12. The role of Kelvin-Helmholtz instability in losses of magnetospheric energetic particles through the magnetopause: High-resolution MHD-test-particle simulations

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, Aleksandr; Sorathia, Kareem; Merkin, Viacheslav

    2016-10-01

    The Earth's magnetopause is a sharp boundary separating the geomagnetic field from interplanetary field and plasma. During increased solar wind driving and geomagnetic activity, energetic particles produced inside the magnetosphere can gain access to the magnetopause and be permanently lost from the system by crossing the boundary into the region of open interplanetary magnetic field lines. The efficiency of the loss process is controlled by the details of particle interaction with the magnetopause boundary. Characterizing this interaction is important for understanding storm-time variability of magnetospheric energetic particle populations including ring current and radiation belts. The magnetopause structure can be very dynamic due, in particular, to the Kelvin-Helmholtz instability (KHI) produced by the velocity shear at the magnetospheric boundary. The goal of this study is to investigate the role of KHI in energetic particle loss through the magnetopause. For the analysis we use large-scale test-particle simulations in the electromagnetic fields computed with a global magnetospheric MHD model with resolution sufficiently high to resolve KHI. We compute the spatial distributions and rates of the magnetopause losses of energetic electrons, hydrogen and oxygen ions, and discuss our results in the context of recent measurements of magnetopause losses from the Magnetospheric Multiscale (MMS) mission.

  13. 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.

  14. Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Király, Péter

    Energetic particles recorded in the Earth environment and in interplanetary space have a multitude of origins, i.e. acceleration and propagation histories. At early days practically all sufficiently energetic particles were considered to have come either from solar flares or from interstellar space. Later on, co-rotating interplanetary shocks, the termination shock of the supersonic solar wind, planetary bow shocks and magnetospheres, and also coronal mass ejections (CME) were recognized as energetic particle sources. It was also recognized that less energetic (suprathermal) particles of solar origin and pick-up ions have also a vital role in giving rise to energetic particles in interplanetary disturbances. The meaning of the term "solar energetic particles" (SEP) is now somewhat vague, but essentially it refers to particles produced in disturbances fairly directly related to solar processes. Variation of intensity fluctuations with energy and with the phase of the solar cycle will be discussed. Particular attention will be given to extremes of time variation, i.e. to very quiet periods and to large events. While quiet-time fluxes are expected to shed light on some basic coronal processes, large events dominate the fluctuation characteristics of cumulated fluence, and the change of that fluctuation with energy and with the phase of the solar cycle may also provide important clues. Mainly ISEE-3 and long-term IMP-8 data will be invoked. Energetic and suprathermal particles that may never escape into interplanetary space may play an important part in heating the corona of the sun.

  15. Prediction of nonlinear evolution character of energetic-particle-driven instabilities

    DOE PAGES

    Duarte, Vinicius N.; Berk, H. L.; Gorelenkov, N. N.; ...

    2017-03-17

    A general criterion is proposed and found to successfully predict the emergence of chirping oscillations of unstable Alfvénic eigenmodes in tokamak plasma experiments. The model includes realistic eigenfunction structure, detailed phase-space dependences of the instability drive, stochastic scattering and the Coulomb drag. The stochastic scattering combines the effects of collisional pitch angle scattering and micro-turbulence spatial diffusion. Furthermore, the latter mechanism is essential to accurately identify the transition between the fixed-frequency mode behavior and rapid chirping in tokamaks and to resolve the disparity with respect to chirping observation in spherical and conventional tokamaks.

  16. Nonlinear simulations of Alfvénic instabilities driven by energetic particles in a reversed shear tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Briguglio, Sergio; Chen, Liu; Fogaccia, Giuliana; Vlad, Gregorio; Zonca, Fulvio

    2013-10-01

    The extended version of nonlinear hybrid magnetohydrodynamic (MHD)-Gyrokinetic code HMGC (XHMGC) is used to investigate the reversed shear Alfvén eigenmodes (RSAE)/energetic particle modes (EPM) driven by an anisotropic Maxwellian energetic particles with reversed shear q profiles. In the region near the minimum-q surface, EPM are shown to exist inside the kinetic low-frequency shear Alfvén continuum gap. Fast non-adiabatic down-ward chirping frequency is found for given equilibrium profiles, which is understood as consequence of nonlinear wave particle dynamics. In our current case, the mode structure is dominated by two neighbor poloidal components, while wave energetic particle interaction is dominated by the sidebands of the dominant transit resonance. S. Briguglio et al., Phys. Plasmas 2, 3711 (1995).

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

    SciTech Connect

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

    2016-05-15

    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.

  18. 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.

  19. Double-kink Fishbone Instability Caused by Circulating Energetic Ions

    SciTech Connect

    Ya.I. Kolesnichenko; V.V. Lutsenko; V.S. Marchenko; R.B. White

    2004-01-12

    The destabilization of double kink modes by the circulating energetic ions in tokamaks with the plasma current having an off-axis maximum is studied. It is shown that the high-frequency fishbone instability [Energetic Particle Mode (EPM)] and the low-frequency (diamagnetic) fishbones are possible for such an equilibrium, their poloidal and toroidal mode numbers being not necessarily equal to unity. A new kind of the EPM instability, ''doublet fishbones,'' is predicted. This instability is characterized by two frequencies; it can occur in a plasma with a non-monotonic radial profile of the energetic ions when the particle orbit width is less than the width of the region where the mode is localized. It is found that the diamagnetic fishbone branch exists even when the orbit width exceeds the mode width; in this case, however, the instability growth rate is relatively small.

  20. Stochastic heating of dust particles in complex plasmas as an energetic instability of a harmonic oscillator with random frequency

    SciTech Connect

    Marmolino, Ciro

    2011-10-15

    The paper describes the occurrence of stochastic heating of dust particles in dusty plasmas as an energy instability due to the correlations between dust grain charge and electric field fluctuations. The possibility that the mean energy (''temperature'') of dust particles can grow in time has been found both from the self-consistent kinetic description of dusty plasmas taking into account charge fluctuations [U. de Angelis, A. V. Ivlev, V. N. Tsytovich, and G. E. Morfill, Phys. Plasmas 12(5), 052301 (2005)] and from a Fokker-Planck approach to systems with variable charge [A. V. Ivlev, S. K. Zhdanov, B. A. Klumov, and G. E. Morfill, Phys. Plasmas 12(9), 092104 (2005)]. Here, a different derivation is given by using the mathematical techniques of the so called multiplicative stochastic differential equations. Both cases of ''fast'' and ''slow'' fluctuations are discussed.

  1. Current energetic particle sensors

    NASA Astrophysics Data System (ADS)

    Fennell, J. F.; Blake, J. B.; Claudepierre, S.; Mazur, J.; Kanekal, S.; O'Brien, P.; Baker, D.; Crain, W.; Mabry, D.; Clemmons, J.

    2016-09-01

    Several energetic particle sensors designed to make measurements in the current decade are described and their technology and capabilities discussed and demonstrated. Most of these instruments are already on orbit or approaching launch. These include the Magnetic Electron Ion Spectrometers (MagEIS) and the Relativistic Electron Proton Telescope (REPT) that are flying on the Van Allen Probes, the Fly's Eye Electron Proton Spectrometers (FEEPS) flying on the Magnetospheric Multiscale (MMS) mission, and Dosimeters flying on the AC6 Cubesat mission. We focus mostly on the electron measurement capability of these sensors while providing summary comments of their ion measurement capabilities if they have any.

  2. Energetic Particles Investigation (EPI)

    NASA Astrophysics Data System (ADS)

    Fischer, H. M.; Mihalov, J. D.; Lanzerotti, L. J.; Wibberenz, G.; Rinnert, K.; Gliem, F. O.; Bach, J.

    1992-05-01

    The EPI instrument operates during the pre-entry phase of the Galileo Probe. The main objective is the study of the energetic particle population in the inner Jovian magnetosphere and in the upper atmosphere. This will be achieved through omnidirectional measurements of electrons, protons, alpha-particles and heavy ions (Z greater than 2) and recording intensity profiles with a spatial resolution of about 0.02 Jupiter radii. Sectored data will also be obtained for electrons, protons, and alpha-particles to determine directional anisotropies and particle pitch angle distributions. The detector assembly is a two-element telescope using totally depleted circular silicon surface-barrier detectors surrounded by cylindrical tungsten shielding. The lower energy threshold of the particle species investigated during the Probe's pre-entry phase is determined by the material thickness of the Probe's rear heat shield which is required for heat protection of the scientific payload during entry into the Jovian atmosphere. The EPI instrument is combined with the Lightning and Radio Emission Detector and both instruments share one interface of the Probe's power, command, and data unit.

  3. 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.

  4. 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.

  5. 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.

  6. Application/extension of the Landau-fluid approach for energetic particle instabilities in stellarators and tokamaks

    NASA Astrophysics Data System (ADS)

    Spong, Don

    2012-10-01

    Reduced dimensionality Landau-fluid models have been useful due to their computational efficiency and ease at evaluating the effects of different physics assumptions. Different challenges are present (global mode structure, finite orbit widths, non-Maxwellian distributions) in applying these methods to EP-driven instabilities than for applications to core micro-turbulence. The TAEFL model has demonstrated that Landau closure methods can be used to introduce the linear resonances that drive Alfvèn (AE) instabilities; this model has recently been extended to include coupling to acoustic waves, and higher order EP moments (providing the flexibility needed for analysis of non-Maxwellian distribution functions). Also, a second-order nonlinear stepper has been implemented (allowing simulation of AE growth/decay cycles) and an eigenvalue solver version for 3D configurations is under development using parallel solvers. Recent applications have included RSAE to TAE frequency sweeps, JET antenna damping measurements, edge and core localized AE's, alpha-driven instabilities in ITER, V&V studies, and EP instabilities in stellarators (HAE, RSAE, TAE) and RFP's. These applications and the ongoing extensions to the model will be discussed.

  7. Energetic particle physics issues for ITER

    SciTech Connect

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

    1996-12-31

    This paper summarizes our present understanding of the following energetic/alpha particle physics issues for the 21 MA, 20 TF coil ITER Interim Design configuration and operational scenarios: (a) toroidal field ripple effects on alpha particle confinement, (b) energetic particle interaction with low frequency MHD modes, (c) energetic particle excitation of toroidal Alfven eigenmodes, and (d) energetic particle transport due to MHD modes. TF ripple effects on alpha loss in ITER under a number of different operating conditions are found to be small with a maximum loss of 1%. With careful plasma control in ITER reversed-shear operation, TF ripple induced alpha loss can be reduced to below the nominal ITER design limit of 5%. Fishbone modes are expected to be unstable for {beta}{sub {alpha}} > 1%, and sawtooth stabilization is lost if the ideal kink growth rate exceeds 10% of the deeply trapped alpha precessional drift frequency evaluated at the q = 1 surface. However, it is expected that the fishbone modes will lead only to a local flattening of the alpha profile due to small banana size. MHD modes observed during slow decrease of stored energy after fast partial electron temperature collapse in JT-60U reversed-shear experiments may be resonant type instabilities; they may have implications on the energetic particle confinement in ITER reversed-shear operation. From the results of various TAE stability code calculations, ITER equilibria appear to lie close to TAE linear stability thresholds. However, the prognosis depends strongly on q profile and profiles of alpha and other high energy particles species. If TAE modes are unstable in ITER, the stochastic diffusion is the main loss mechanism, which scales with ({delta}B{sub r}/B){sup 2}, because of the relatively small alpha particle banana orbit size. For isolated TAE modes the particle loss is very small, and TAE modes saturate via the resonant wave-particle trapping process at very small amplitude.

  8. 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.

  9. Energetic particles in solar flares

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Paizis, C.; Colgate, S. A.; Dulk, G. A.; Hoyng, P.; Knight, J. W.; Lin, R. P.; Melrose, D. B.; Orrall, F.; Shapiro, P. R.

    1980-01-01

    The various manifestations of energetic particles in solar flares are examined, and possible mechanisms for the acceleration of these particles are considered. Hard X-ray observations and possible mechanisms for the production of the dominant form of solar energetic particles, electrons with energies between 10 and 100 keV, are discussed, with consideration of thin-target models, thick-target models and thick-target models with reverse currents, and first-phase acceleration mechanisms for energetic electrons emitting impulsive microwave and fast-drift Type III radio bursts as well as impulsive hard X rays, which are detected themselves 20 min after the flare at 1 AU are considered. Radio evidence on the number, energy and pitch-angle distributions of energetic particles produced during solar flares is summarized, and observations at 1 AU of proton and electron energy spectra, the proton/electron ratio and energetic particle events rich in He-3 from solar flares are discussed. Finally, consideration is given to gamma-ray evidence of nuclear reactions in flares and white-light flares

  10. Observation of an Energetic-Particle-Driven Instability in the Wall-Stabilized High-beta Plasmas in the JT-60U Tokamak

    SciTech Connect

    Matsunaga, G.; Aiba, N.; Shinohara, K.; Sakamoto, Y.; Isayama, A.; Takechi, M.; Suzuki, T.; Oyama, N.; Asakura, N.; Kamada, Y.; Ozeki, T.

    2009-07-24

    We have observed a bursting mode in the high-beta plasmas above the ideal beta limit without a conducting wall. The mode frequency is chirping down as the mode amplitude increases, and its initial value is close to the precession frequency of the trapped energetic particle from the perpendicular neutral beams. The mode structure is radially extended with a peak around the q=2 surface. This mode can finally trigger the resistive wall mode (RWM) despite enough plasma rotation for RWM stabilization. It is concluded that the mode is driven by trapped energetic particles. The mode is attributed to the interaction between the trapped energetic particles and a marginally stable mode in the wall-stabilized high-beta{sub N} region.

  11. Energetic particle effects on global magnetohydrodynamic modes

    SciTech Connect

    Cheng, C.Z. )

    1990-06-01

    The effects of energetic particles on magnetohydrodynamic (MHD) type modes are studied using analytical theories and the nonvariational kinetic-MHD stability code (NOVA-K) ({ital Workshop} {ital on} {ital Theory} {ital of} {ital Fusion} {ital Plasmas}, (Societa Italiana di Fisica, Bologna, 1987), p. 185). In particular, 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 are addressed. Analytical theories are presented to help explain the NOVAresults. For energetic trapped particles generated by neutral beam injection or ion cyclotron resonant heating, a stability window for the {ital n}=1 internal kink mode in the hot particle beta space exists even in the absence of core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to resonantly excite instability of the {ital 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.

  12. 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.

  13. 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

  14. 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.; hide

    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

  15. Heliospheric Observations of Energetic Particles

    NASA Technical Reports Server (NTRS)

    Summerlin, Errol J.

    2011-01-01

    Heliospheric observations of energetic particles have shown that, on long time averages, a consistent v^-5 power-law index arises even in the absence of transient events. This implies an ubiquitous acceleration process present in the solar wind that is required to generate these power-law tails and maintain them against adiabatic losses and coulomb-collisions which will cool and thermalize the plasma respectively. Though the details of this acceleration process are being debated within the community, most agree that the energy required for these tails comes from fluctuations in the magnetic field which are damped as the energy is transferred to particles. Given this source for the tail, is it then reasonable to assume that the turbulent LISM should give rise to such a power-law tail as well? IBEX observations clearly show a power-law tail of index approximately -5 in energetic neutral atoms. The simplest explanation for the origins of these ENAs are that they are energetic ions which have charge-exchanged with a neutral atom. However, this would imply that energetic ions possess a v^-5 power-law distribution at keV energies at the source of these ENAs. If the source is presumed to be the LISM, it provides additional options for explaining the, so called, IBEX ribbon. This presentation will discuss some of these options as well as potential mechanisms for the generation of a power-law spectrum in the LISM.

  16. 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.

  17. 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.

  18. Energetic Charged Particles Above Thunderclouds

    NASA Astrophysics Data System (ADS)

    Füllekrug, Martin; Diver, Declan; Pinçon, Jean-Louis; Phelps, Alan D. R.; Bourdon, Anne; Helling, Christiane; Blanc, Elisabeth; Honary, Farideh; Harrison, R. Giles; Sauvaud, Jean-André; Renard, Jean-Baptiste; Lester, Mark; Rycroft, Michael; Kosch, Mike; Horne, Richard B.; Soula, Serge; Gaffet, Stéphane

    2013-01-01

    The French government has committed to launch the satellite TARANIS to study transient coupling processes between the Earth's atmosphere and near-Earth space. The prime objective of TARANIS is to detect energetic charged particles and hard radiation emanating from thunderclouds. The British Nobel prize winner C.T.R. Wilson predicted lightning discharges from the top of thunderclouds into space almost a century ago. However, new experiments have only recently confirmed energetic discharge processes which transfer energy from the top of thunderclouds into the upper atmosphere and near-Earth space; they are now denoted as transient luminous events, terrestrial gamma-ray flashes and relativistic electron beams. This meeting report builds on the current state of scientific knowledge on the physics of plasmas in the laboratory and naturally occurring plasmas in the Earth's atmosphere to propose areas of future research. The report specifically reflects presentations delivered by the members of a novel Franco-British collaboration during a meeting at the French Embassy in London held in November 2011. The scientific subjects of the report tackle ionization processes leading to electrical discharge processes, observations of transient luminous events, electromagnetic emissions, energetic charged particles and their impact on the Earth's atmosphere. The importance of future research in this area for science and society, and towards spacecraft protection, is emphasized.

  19. Energetic Particles in Saturn's Magnetotail

    NASA Astrophysics Data System (ADS)

    Mitchell, D. G.; Carbary, J. F.; Krupp, N.; Krimigis, S. M.; Hamilton, D. C.; Kane, M.

    2007-12-01

    Energetic particle measurements in Saturn's magnetotail reveal a magnetotail dominated by Saturn's rotational dynamics as far back in the tail as 60 Rs, rarely but sometimes spectacularly disrupted by tail reconnection events. Although Cassini spent little time in the tail, and even less at the location of the tail current sheet, the time spent there revealed a pattern of very regular encounters with the energetic particles that fill the current sheet, usually once every Saturn rotation. Carbary et al. 2007a, b show that energetic electrons reappear every rotation when the spacecraft is sufficiently close to the current sheet location, and further that they lie along a spiral in longitude when mapped into the SKR coordinate system (Kurth et al., 2007). Energetic ions are also observed in the same locations, with a mix of hydrogen and oxygen not very different from that observed in the magnetosphere between 10 and 20 Rs. These ions generally display velocities approximately in the corotation direction, but with magnitudes well below rigid corotation (Kane et al., 2007, manuscript in preparation). Two other classes of energetic particle events are also seen in the magnetotail. The first consists of energetic ion and electron beams, likely accelerated in the auroral zone over downward current regions. The second are those generated in tail reconnection events (e.g., Jackman et al., 2007; Hill et al. 2007). We will give examples of all of these phenomena, including both in situ measurements and ENA images/movies. Carbary, J.~F., Mitchell, D.~G., Krimigis, S.~M., Hamilton, D.~C., Krupp, N., Charged particle periodicities in Saturn's outer magnetosphere, Journal of Geophysical Research (Space Physics) 112, 6246 {2007JGRA..11206246C} 2007a Carbary, J. F., D. G. Mitchell, S. M. Krimigis, and N. Krupp (2007), Evidence for spiral pattern in Saturn's magnetosphere using the new SKR longitudes, Geophys. Res. Lett., 34, L13105, doi:10.1029/2007GL030167 2007b Kurth, W. S., A

  20. 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.

  1. 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.

  2. 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.

  3. Paleo Mars energetic particle precipitation

    NASA Astrophysics Data System (ADS)

    Alho, Markku; McKenna-Lawlor, Susan; Kallio, Esa

    2015-12-01

    A young Mars may well have possessed a global dipolar magnetic field that provided protection for the planet's atmosphere from the space weather environment. Against this background, we study in the present paper the effect of various dipole magnetic fields on particle precipitation (range 10 keV-4.5 MeV) on the upper Martian atmosphere as the magnetosphere gradually declined to become an induced magnetosphere. We utilized a hybrid plasma model to provide, in a self-consistent fashion, simulations (that included ion-kinetic effects) of the interaction between the Martian obstacle (magnetized or otherwise) and the solar wind. Besides the intrinsic dipole, with field strengths of ~100 nT and below, we assume modern solar and atmospheric parameters to examine the effect of the single variable, that is the dipole strength. We thereby investigated the precipitation of solar energetic particles on the upper atmosphere of the planet in circumstances characterized by the evolution of a diminishing Martian dynamo that initially generated an ideal dipolar field. It is demonstrated that an assumed Martian dipole would have provided, in the energy range investigated, significant shielding against proton impingement and that the interaction between the solar wind and the assumed Martian magnetic dipole would have been responsible for generating the shielding effect identified.

  4. 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.

  5. 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.

  6. 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.

  7. Solar Energetic Particle Spectral Breaks

    NASA Astrophysics Data System (ADS)

    Mewaldt, R.; Cohen, C.; Mason, G.; Desai, M.; Labrador, A.; Lee, M.; Li, G.

    2008-05-01

    A new generation of instruments during solar cycle 23 made it possible to measure solar energetic particle (SEP) energy spectra for many species over a broad energy interval (~0.1 to ~100 MeV/nucleon). These observations revealed that most large SEP events have power-law spectra below a few MeV/nucleon with rather hard spectral indices, followed by spectral steepening at higher energies. These spectral breaks are ordered by species - the spectra of lighter elements break at higher energy/nucleon than those for heavier species. To understand the charge-to-mass (Q/M) dependence of these spectral breaks, we have located the breaks for a range of species (e.g., H, He, C, N, O, Ne, Mg, Si, and Fe) and correlated the break locations with either measured or average Q/M ratios. As of this writing there are results for 13 large SEP events, based on data from ACE, GOES, SAMPEX, and STEREO, and charge state data from SAMPEX and ACE. We find that the location of the breaks is generally well-represented by a power-law in Q/M. This power-law fit can be related to the Q/M- dependence of the interplanetary diffusion coefficient and to the turbulence spectrum of the interplanetary magnetic field. We find that the slope of the deduced turbulence spectra are correlated with Fe/O and the proton fluence. These results support the idea that proton-amplified Alfven waves are generated in large SEP events, as expected for acceleration at parallel shocks.

  8. 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.

  9. Shock Wave Structure Mediated by Energetic Particles

    NASA Astrophysics Data System (ADS)

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2016-12-01

    Energetic particles such as cosmic rays, Pick Up Ions (PUIs), and solar energetic particles can affect all facets of plasma physics and astrophysical plasma. Energetic particles play an especially significant role in the dissipative process at shocks and in determining their structure. The very interesting recent observations of shocks in the inner heliosphere found that many shocks appear to be significantly mediated by solar energetic particles which have a pressure that exceeds considerably both the thermal gas pressure and the magnetic field pressure. Energetic particles contribute an isotropic scalar pressure to the plasma system at the leading order, as well as introducing dissipation via a collisionless heat flux (diffusion) at the next order and a collisionless stress tensor (viscosity) at the second order. Cosmic-ray modified shocks were discussed by Axford et al. (1982), Drury (1983), and Webb (1983). Zank et al. (2014) investigated the incorporation of PUIs in the supersonic solar wind beyond 10AU, in the inner Heliosheath and in the Very Local Interstellar Medium. PUIs do not equilibrate collisionally with the background plasma in these regimes. In the absence of equilibration between plasma components, a separate coupled plasma description for the energetic particles is necessary. This model is used to investigate the structure of shock waves assuming that we can neglect the magnetic field. Specifically, we consider the dissipative role that both the energetic particle collisionless heat flux and viscosity play in determining the structure of collisionless shock waves. We show that the incorporation of both energetic particle collisionless heat flux and viscosity is sufficient to completely determine the structure of a shock. Moreover, shocks with three sub-shocks converge to the weak sub-shocks. This work differs from the investigation of Jokipii and Williams (1992) who restricted their attention to a cold thermal gas. For a cold thermal non

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

    NASA Astrophysics Data System (ADS)

    Cao, Jintao; Qiu, Zhiyong; Zonca, Fulvio

    2015-12-01

    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.

  11. 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.

  12. 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.

  13. Numerical simulations of toroidal Alfven instabilities excited by trapped energetic ions

    SciTech Connect

    Zheng, L.-J.; Chen, Liu; Santoro, R. A.

    2000-06-01

    Extensive magnetohydrodynamic-gyrokinetic hybrid simulations have been carried out to study the excitations of Alfven instabilities by trapped energetic ions in tokamak plasmas. Depending on the parameters, the most unstable mode can be either the toroidal Alfven eigenmode (TAE) or the energetic-particle mode (EPM). In both cases, the dominant instability driving mechanism is the resonance with the trapped-particle magnetic precessional drifts. The mode frequencies of the most unstable modes, meanwhile, tend to be near the toroidal frequency gap in order to minimize the continuum damping. It is also demonstrated that the instabilities can be quenched by reversing the magnetic precessional drifts via either negative magnetic shear or locating the magnetic turning points in the inner (strong B) side of the torus. (c) 2000 American Institute of Physics.

  14. Structure of Energetic Particle Mediated Shocks Revisited

    NASA Astrophysics Data System (ADS)

    Mostafavi, P.; Zank, G. P.; Webb, G. M.

    2017-05-01

    The structure of collisionless shock waves is often modified by the presence of energetic particles that are not equilibrated with the thermal plasma (such as pickup ions [PUIs] and solar energetic particles [SEPs]). This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM), where observations of shock waves (e.g., in the inner heliosphere) show that both the magnetic field and thermal gas pressure are less than the energetic particle component pressures. Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI-mediated plasma model is structurally identical to the classical cosmic ray two-fluid model, we note that the presence of viscosity, at least formally, eliminates the need for a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the HTS, we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1. We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  15. Capillary instabilities in thin films. I. Energetics

    SciTech Connect

    Srolovitz, D.J.; Safran, S.A.

    1986-07-01

    A stability theory is presented which describes the conditions under which thin films rupture. It is found that holes in the film will either grow or shrink, depending on whether their initial radius is larger or smaller than a critical value. If the holes grow large enough, they impinge to form islands; the size of which are determined by the surface energies. The formation of grooves where the grain boundary meets the free surface is a potential source of holes which can lead to film rupture. Equilibrium grain boundary groove depths are calculated for finite grain sizes. Comparison of groove depth and film thickness yields microstructural conditions for film rupture. In addition, pits which form at grain boundary vertices, where three grains meet, are another source of film instability.

  16. Energetic neutral particles from Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Cheng, A. F.

    1986-01-01

    The Voyager 1 spacecraft has detected energetic neutral particles escaping from the magnetospheres of Jupiter and Saturn. These energetic neutrals are created in charge exchange reactions between radiation belt ions and ambient atoms or molecules in the magnetosphere. If the Io torus is assumed to be the dominant Jovian source region for energetic neutrals, the Voyager observations can be used to infer upper limits to the average ion intensities there below about 200 keV. No readily interpretable in-situ measurements are available in the Io torus at these energies. The middle and outer Jovian magnetospheres may also be a significant source of energetic neutrals. At Saturn, the observed neutral particle count rates are too high to be explained by charge exchange between fast protons and H atoms of the Titan torus. Most of the energetic neutrals may be produced by charge exchanges between heavy ions and a neutral cloud containing H2O in Saturn's inner magnetosphere. If so, the Voyager measurements of energetic neutral fluxes would be the first detected emissions from this region of Saturn's magnetosphere.

  17. Stability of Ballooning Modes in Tokamaks with Energetic Particles.

    NASA Astrophysics Data System (ADS)

    Dominguez Vergara, Nicolas

    The effects of energetic particles are of interest since fast ions are present in neutral-beam and rf-heated tokamaks and will occur in ignition devices in the form of alpha particles. Moreover, it may be desirable to create such particles by auxiliary heating in order to exploit their stabilizing properties and thus attain a high beta plasma. Here a range of issues related to the stabilization of MHD ballooning modes in tokamaks by using energetic particles is investigated analytically and numerically. The presence of a highly energetic plasma component can stabilize MHD ballooning modes in tokamaks and may allow direct access to the high-beta second stability regime. Here, an improved estimate of such stability has been obtained, in the large-aspect-ratio circular limit, by means of a variational refinement of the lower bound for the energetic particle potential energy. We also investigate the effect of various profiles for the hot particle pressure on stability, and we explore the stability of off-angle modes. Moderately energetic particles, however, can destabilize the plasma through resonant interaction at their curvature drift fre- quency. We study these so-called "balloon-bone" modes, using a delta function model for their resonant response. The complete forms of the Mercier solutions in the MHD region are obtained analytically and numerically. Matched onto the inertia layer, these solutions give a dispersion relation valid for finite shear and poloidal beta values, which then is analyzed by the Nyquist technique. Results are presented for the limit in which Alfvenic effects are negligible, namely, (,)(omega)(,dh) << (omega)(,A), where (,)(omega)(,dh) is the curvature drift frequency and (omega)(,A) is the Alfven frequency, and in which the energetic particles are modeled with a slowing-down distribution in energy. Finally, even if the ideal modes and resonantly -excited modes can be simultaneously stabilized, resistive ballooning instabilities may persist

  18. Three-dimensional effects on energetic particle confinement and stability

    SciTech Connect

    Spong, D. A.

    2011-05-15

    Energetic particle populations in magnetic confinement systems are sensitive to symmetry-breaking effects due to their low collisionality and long confined path lengths. Broken symmetry is present to some extent in all toroidal devices. As such effects preclude the existence of an ignorable coordinate, a fully three-dimensional analysis is necessary, beginning with the lowest order (equilibrium) magnetic fields. Three-dimensional techniques that have been extensively developed for stellarator configurations are readily adapted to other devices such as rippled tokamaks and helical states in reversed field pinches. This paper will describe the methods and present an overview of recent examples that use these techniques for the modeling of energetic particle confinement, Alfven mode structure and fast ion instabilities.

  19. Energetic-Electron-Driven Instability in the Helically Symmetric Experiment

    NASA Astrophysics Data System (ADS)

    Deng, C. B.; Brower, D. L.; Breizman, B. N.; Spong, D. A.; Almagri, A. F.; Anderson, D. T.; Anderson, F. S. B.; Ding, W. X.; Guttenfelder, W.; Likin, K. M.; Talmadge, J. N.

    2009-07-01

    Energetic electrons generated by electron cyclotron resonance heating are observed to drive instabilities in the quasihelically symmetric stellarator device. The coherent, global fluctuations peak in the plasma core and are measured in the frequency range of 20-120 kHz. Mode propagation is in the diamagnetic drift direction of the driving species. When quasihelical symmetry is broken, the mode is no longer observed. Experimental observations indicate that the unstable mode is acoustic rather than Alfvénic.

  20. 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

  1. Solar Energetic Particle Spectral Breaks

    SciTech Connect

    Mewaldt, R.A.; Cohen, C.M.S.; Labrador, A.W.; Cummings, A.C.; Leske, R.A.; Stone, E.C.; Mason, G.M.; Desai, M.I.; Looper, M.L.; Mazur, J.E.; Haggerty, D.E.; Maclennan, C.G.; Li, G.; Wiedenbeck, M.E.

    2005-08-01

    The five large solar particle events during October-November 2003 presented an opportunity to test shock acceleration models with in-situ observations. We use solar particle spectra of H to Fe ions, measured by instruments on ACE, SAMPEX, and GOES-11, to investigate the Q/M-dependence of spectral breaks in the 28 October 2003 event. We find that the break energies scale as (Q/M)b with b {<=} 1.56 to 1.75, somewhat less than predicted. We also conclude that SEP spectra >100 MeV/nucleon are best fit by a double power-law shape.

  2. The energetic alpha particle transport method EATM

    SciTech Connect

    Kirkpatrick, R.C.

    1998-02-01

    The EATM method is an evolving attempt to find an efficient method of treating the transport of energetic charged particles in a dynamic magnetized (MHD) plasma for which the mean free path of the particles and the Larmor radius may be long compared to the gradient lengths in the plasma. The intent is to span the range of parameter space with the efficiency and accuracy thought necessary for experimental analysis and design of magnetized fusion targets.

  3. Composition of energetic particles from solar flares.

    PubMed

    Garrard, T L; Stone, E C

    1994-10-01

    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.

  4. 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.

  5. Energetic charged particle interactions at icy satellites

    NASA Astrophysics Data System (ADS)

    Nordheim, T.; Hand, K. P.; Paranicas, C.; Howett, C.; Hendrix, A. R.

    2016-12-01

    Satellites embedded within planetary magnetospheres are typically exposed to bombardment by charged particles, from thermal plasma to more energetic particles at radiation belt energies. At many planetary satellites, energetic charged particles are typically unimpeded by patchy atmospheres or induced satellite magnetic fields and instead are stopped in the surface itself. Most of these primaries have ranges in porous water ice that are at most centimeters, but some of their secondary photons, emitted during the deceleration process, can reach meter depths [Paranicas et al., 2002, 2004; Johnson et al., 2004]. Examples of radiation-induced surface alteration includes sputtering, radiolysis and grain sintering, processes that are capable of significantly altering the physical properties of surface material. Thus, accurate characterization of energetic charged particle weathering at icy satellites is crucial to a more comprehensive understanding of these bodies. At Saturn's inner mid-size moons remote sensing observations by several instruments onboard the Cassini spacecraft have revealed distinct weathering patterns which have been attributed to energetic electron bombardment of the surface [Howett et al., 2011, 2012, 2014; Schenk et al., 2011; Paranicas et al., 2014]. In the Jovian system, radiolytic production of oxidants has been invoked as a potential source of energy for life which may reside in the sub-surface ocean of its satellite Europa [Johnson et al., 2003; Hand et al., 2007; Vance et al., 2016]. Here we will discuss the near-surface energetic charged particle environment of icy satellites, with particular emphasis on comparative studies between the Saturnian and Jovian systems and interpretation of remote sensing observations by instruments onboard missions such as Cassini and Galileo. In addition, we will discuss implications for surface sampling by future lander missions (e.g. the proposed Europa lander now under study).

  6. Solar Energetic Particles: Acceleration and Observations

    NASA Astrophysics Data System (ADS)

    Sako, Takashi

    Research of solar energetic particles (SEPs) is important in understanding particle acceleration, transport and interactions taking place in the universe. The importance of space weather to modern human life is also increasing. In this lecture, I introduce a selected subset of SEP observations together with observation techniques and future plans. The aim is to connect these SEP observations with associated particle acceleration mechanisms and the subsequent transport and interaction processes. Because the observational properties are determined by different processes, a wide range of observations is necessary in order to fully understand the phenomena taking place. I will also give an overview of the role of the SEP studies in general astrophysics.

  7. 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.

  8. 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.

  9. 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.

  10. Tutorial on Solar Energetic-Particle Events

    NASA Technical Reports Server (NTRS)

    vonRosenvinge, Tycho T.

    2004-01-01

    Particles from the Sun at energies above approx. 1 MeV/nucleon have been studied in space for over 35 years. There have been major advances in instrumentation for studying elemental and isotopic composition, kinetic energy, charge states, time intensity histories, and anisotropies of energetic particles. There have also been extensive improvements in the observations of solar phenomena, including radio bursts, Coronal Mass Ejections (CMEs), and solar photons from soft X-ray to gamma-ray energies. Despite these advances, there is a lack of agreement as to the acceleration processes responsible for the particles seen in space shortly after the solar event. In particular, the relative importance of solar flares and CME-driven shocks is disputed for events of moderate to larger size. The reasons for this will be reviewed, and the prospects for resolving this issue will be evaluated.

  11. 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.

  12. Energetic particle observations at geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Geoffrey, E.; Reeves, D.

    The region of space near geosynchronous altitudes is important for the processes which contribute to magnetic storms. During substorms magnetic energy is converted to particle kinetic energy resulting in the 'substorm injections' commonly observed at geosynchronous orbit. These injections are manifested in energies from a few tens of keV to hundreds of keV and, on occasion, to the MeV energy range. The injected particles are subject to gradient and curvature drifts and therefore contribute to the ring current. It is common to think of a magnetic storm as a superposition of substorms in which the injection rate into the ring current exceeds the loss rate due to scattering, diffusion, and precipitation. In this paper the authors review current understanding of substorm injections and examine geosynchronous energetic particle data for the signatures of magnetic storms and for clues to the storm-substorm connection.

  13. 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.

  14. Energetic particle observations at geosynchronous orbit

    SciTech Connect

    Geoffrey, E.; Reeves, D.

    1994-10-01

    The region of space near geosynchronous altitudes is important for the processes which contribute to magnetic storms. During substorms magnetic energy is converted to particle kinetic energy resulting in the {open_quotes}substorm injections{close_quotes} commonly observed at geosynchronous orbit. These injections are manifested in energies from a few tens of keV to hundreds of keV and, on occasion, to the MeV energy range. The injected particles are subject to gradient and curvature drifts and therefore contribute to the ring current. It is common to think of a magnetic storm as a superposition of substorms in which the injection rate into the ring current exceeds the loss rate due to scattering, diffusion, and precipitation. In this paper the authors review current understanding of substorm injections and examine geosynchronous energetic particle data for the signatures of magnetic storms and for clues to the storm-substorm connection.

  15. The MAVEN Solar Energetic Particle instrument

    NASA Astrophysics Data System (ADS)

    Dunn, P.; Lillis, R. J.; Larson, D. E.; Lin, R. P.; Jakosky, B. M.

    2012-12-01

    The Solar Energetic Particle (SEP) instrument will travel to Mars onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) Mission, launching in November 2013. 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 will characterize such events at Mars by measuring energetic protons and electrons in the energy range absorbed by the upper atmosphere. 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 will measure particle fluxes from ~20 to ~107 cm-2s-1sr-1. Here we present a full description of the instrument, as well as GEANT4 simulations of the detailed detector response.; Cross-section view of SEP sensor. Collimators are shown in yellow, baffles are in black. The sweep magnet (blue and brown) prevents electrons < 350 keV from reaching the detector stack (mounted on circuit board shown in green) from the left. A Kapton foil (not visible) prevent ions < 250 keV from reaching the stack from the right.

  16. Stimulated Emission of Energetic Particles (SEEP).

    DTIC Science & Technology

    1987-11-30

    a.... W W w w w w w I I li IJr Ir % i "f J2 I l AD-A 188 724 MLMSCD068456 For Period Ending 30 September 1987 CD Contract N00014-79-C4824 0 IC FILE...CLASSIFICATION 0 -UNCLASSIFIED/UNLIMITED [ SAME AS RPT C:" DTIC USERS UNCLASSIFIED 22a NAME OF RESPONSIBLE INDIVIDUAL 22b TELEPHONE (Include Area Code) 22c O...34---" ,. LMSC/D068456 . 0 SEEP FINAL REPORT I. OBJECTIVES OF THE SEEP PROGRAM The SEEP (Stimulated Emission of Energetic Particles) program had important

  17. Measurement of energetic-particle-driven core magnetic fluctuations and induced fast-ion transport

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, W. X.; Brower, D. L.; Koliner, J. J.; Eilerman, S.; Reusch, J. A.; Anderson, J. K.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Liu, D.

    2013-03-01

    Internal fluctuations arising from energetic-particle-driven instabilities, including both density and radial magnetic field, are measured in a reversed-field-pinch plasma. The fluctuations peak near the core where fast ions reside and shift outward along the major radius as the instability transits from the n = 5 to n = 4 mode. During this transition, strong nonlinear three-wave interaction among multiple modes accompanied by enhanced fast-ion transport is observed.

  18. Solar filament eruptions and energetic particle events

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.; Cliver, E. W.; Cane, H. V.; Mcguire, R. E.; Stone, R. G.

    1986-01-01

    The 1981 December 5 solar filament eruption that is associated with an energetic (E greater than 50 MeV) particle event observed at 1 AU. The eruption was photographed in H-alpha and was observed by the Solwind whitelight coronagraph on P78-1. It occurred well away from any solar active region and was not associated with an impulsive microwave burst, indicating that magnetic complexity and a detectable impulsive phase are not required for the production of a solar energetic particle (SEP) event. No metric type II or IV emission was observed, but an associated interplanetary type II burst was detected by the low-frequency radio experiment on ISEE 3. The December 5 and two other SEP events lacking evidence for low coronal shocks had unusually steep energy spectra (gamma greater than 3.5). In terms of shock acceleration, this suggests that shocks formed relatively high in the corona may produce steeper energy spectra than those formed at lower altitudes. It is noted that the filament itself maybe one source of the ions accelerated to high energies, since it is the only plausible coronal source of the He(+) ions observed in SEP events.

  19. Solar energetic particle events observed by MAVEN

    NASA Astrophysics Data System (ADS)

    Lee, C. O.; Lillis, R. J.; Larson, D. E.; Dunn, P.; Brain, D.; Halekas, J. S.; Espley, J. R.; Zeitlin, C.; Ehresmann, B.; Hassler, D.; Guo, J.; Luhmann, J. G.; Jakosky, B. M.

    2016-12-01

    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 several coronal mass ejections (CMEs) have 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 rotations due to the persistent coronal hole sources of high speed solar wind. 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 the numerical Wang-Sheeley-Arge (WSA)-Enlil simulations of the heliospheric conditions. A comparison with the radiation dose rates measured by the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD) reveals a lack of detectable ground signatures during the onset of the highest energy SEPs for the events observed by MAVEN, indicating that the SEPs fully deposit their energy in the Martian atmosphere. We will discuss the consequences of SEPs at Mars for a number of events observed over the course of the MAVEN mission.

  20. 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.

  1. Acceleration and Propagation of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Klein, Karl-Ludwig; Dalla, Silvia

    2017-07-01

    Solar Energetic Particles (SEPs) are an important component of Space Weather, including radiation hazard to humans and electronic equipment, and the ionisation of the Earth's atmosphere. We review the key observations of SEPs, our current understanding of their acceleration and transport, and discuss how this knowledge is incorporated within Space Weather forecasting tools. Mechanisms for acceleration during solar flares and at shocks driven by Coronal Mass Ejections (CMEs) are discussed, as well as the timing relationships between signatures of solar eruptive events and the detection of SEPs in interplanetary space. Evidence on how the parameters of SEP events are related to those of the parent solar activity is reviewed and transport effects influencing SEP propagation to near-Earth locations are examined. Finally, the approaches to forecasting Space Weather SEP effects are discussed. We conclude that both flare and CME shock acceleration contribute to Space Weather relevant SEP populations and need to be considered within forecasting tools.

  2. 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.

  3. ENERGETIC PARTICLE DIFFUSION IN CRITICALLY BALANCED TURBULENCE

    SciTech Connect

    Laitinen, T.; Dalla, S.; Kelly, J.; Marsh, M.

    2013-02-20

    Observations and modeling suggest that the fluctuations in magnetized plasmas exhibit scale-dependent anisotropy, with more energy in the fluctuations perpendicular to the mean magnetic field than in the parallel fluctuations and the anisotropy increasing at smaller scales. The scale dependence of the anisotropy has not been studied in full-orbit simulations of particle transport in turbulent plasmas so far. In this paper, we construct a model of critically balanced turbulence, as suggested by Goldreich and Sridhar, and calculate energetic particle spatial diffusion coefficients using full-orbit simulations. The model uses an enveloped turbulence approach, where each two-dimensional wave mode with wavenumber k is packed into envelopes of length L following the critical balance condition, L{proportional_to}k {sup -2/3} , with the wave mode parameters changing between envelopes. Using full-orbit particle simulations, we find that both the parallel and perpendicular diffusion coefficients increase by a factor of two, compared to previous models with scale-independent anisotropy.

  4. Solar Energetic Particle Trapping During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Hudson, M.; Kress, B.; Blake, J. B.; Mazur, J.

    2007-12-01

    The prompt trapping of Solar Energetic Particles (SEPs) in the inner magnetosphere inside of L = 4 has been reported, including protons and heavier ions, in association with high speed interplanetary shocks and Storm Sudden Commencements (SSCs). These observations include the Bastille Day 2000 CME-driven storm as well as two in November 2001, which produced a long-lived new proton belt, as well as trapping of heavy ions up to Fe in all three cases. A survey of such events around the most recent solar maximum, including high altitude measurements from Polar, HEO and ICO satellites along with low altitude measurements from SAMPEX, indicates similarities to the well-studied March 24, 1991 SSC event. In this event, electrons and protons in drift resonance with a magnetosonic impulse were transported radially inward, requiring a source population which is multi-MeV at geosynchronous. A requirement for such shock-induced acceleration is a high-speed CME- shock at 1 AU, which launches a perturbation with comparable velocity inside the magnetosphere. Secondly, there must be a source population which is drift-resonant with the impulse. The CME-shock itself is a source of solar energetic particles, both protons and heavy ions, with higher fluxes and harder spectra associated with faster moving CMEs. A 3D Lorentz integration of SEP trajectories in electric and magnetic fields taken from the Lyon-Fedder-Mobarry (LFM) global MHD model, using solar wind input parameters from spacecraft measurements upstream from the bow shock, has been carried out for two November, 2001 SEP trapping events, and a CME-shock associated with the Halloween 2003 storm period, 29 October, which transported outer zone electrons and trapped solar energetic electrons into around L = 2.5, with little effect on SEPs. These results indicate that an enhancement in solar wind dynamic pressure for these events plays a role in the observed injection of ions (and electrons) to low L-values, as does the extent of

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Atypical energetic particle events observed prior energetic particle enhancements associated with corotating interaction regions

    NASA Astrophysics Data System (ADS)

    Khabarova, Olga; Malandraki, Olga; Zank, Gary; Jackson, Bernard; Bisi, Mario; Desai, Mihir; Li, Gang; le Roux, Jakobus; Yu, Hsiu-Shan

    2017-04-01

    Recent studies of mechanisms of particle acceleration in the heliosphere have revealed the importance of the comprehensive analysis of stream-stream interactions as well as the heliospheric current sheet (HCS) - stream interactions that often occur in the solar wind, producing huge magnetic cavities bounded by strong current sheets. Such cavities are usually filled with small-scale magnetic islands that trap and re-accelerate energetic particles (Zank et al. ApJ, 2014, 2015; le Roux et al. ApJ, 2015, 2016; Khabarova et al. ApJ, 2015, 2016). Crossings of these regions are associated with unusual variations in the energetic particle flux up to several MeV/nuc near the Earth's orbit. These energetic particle flux enhancements called "atypical energetic particle events" (AEPEs) are not associated with standard mechanisms of particle acceleration. The analysis of multi-spacecraft measurements of energetic particle flux, plasma and the interplanetary magnetic field shows that AEPEs have a local origin as they are observed by different spacecraft with a time delay corresponding to the solar wind propagation from one spacecraft to another, which is a signature of local particle acceleration in the region embedded in expanding and rotating background solar wind. AEPEs are often observed before the arrival of corotating interaction regions (CIRs) or stream interaction regions (SIRs) to the Earth's orbit. When fast solar wind streams catch up with slow solar wind, SIRs of compressed heated plasma or more regular CIRs are created at the leading edge of the high-speed stream. Since coronal holes are often long-lived structures, the same CIR re-appears often for several consecutive solar rotations. At low heliographic latitudes, such CIRs are typically bounded by forward and reverse waves on their leading and trailing edges, respectively, that steepen into shocks at heliocentric distances beyond 1 AU. Energetic ion increases have been frequently observed in association with CIR

  12. Zonostrophic instability driven by discrete particle noise

    DOE PAGES

    St-Onge, D. A.; Krommes, J. A.

    2017-04-01

    The consequences of discrete particle noise for a system possessing a possibly unstable collective mode are discussed. It is argued that a zonostrophic instability (of homogeneous turbulence to the formation of zonal flows) occurs just below the threshold for linear instability. The scenario provides a new interpretation of the random forcing that is ubiquitously invoked in stochastic models such as the second-order cumulant expansion or stochastic structural instability theory; neither intrinsic turbulence nor coupling to extrinsic turbulence is required. A representative calculation of the zonostrophic neutral curve is made for a simple two-field model of toroidal ion-temperature-gradient-driven modes. To themore » extent that the damping of zonal flows is controlled by the ion-ion collision rate, the point of zonostrophic instability is independent of that rate. Published by AIP Publishing.« less

  13. Energetic ions upstream of the earth's bow shock during an energetic storm particle event

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Ipavich, F. M.

    1983-01-01

    Simultaneous observations of low-energy protons and alpha particles from ISEE 3 far upstream and from ISEE 1 close to the earth's bow shock during the passage of an interplanetary shock wave with its associated energetic storm particles are presented. Intensities, spectra, and anisotropies of the energetic storm particles are modified due to the interaction of these particles with the earth's bow shock. An intensity spike observed at ISEE 1 during the passage of the interplanetary shock is interpreted as being due to postacceleration of energetic storm particles at the bow shock by the first-order Fermi mechanism. The spikes observed at ISEE 1 after the passage of the interplanetary shock are most probably due to reflection of the energetic storm particles at the bow shock.

  14. Energetic charged particles in the uranian magnetosphere.

    PubMed

    Stone, E C; Cooper, J F; Cummings, A C; McDonald, F B; Trainor, J H; Lal, N; McGuire, R; Chenette, D L

    1986-07-04

    During the encounter with Uranus, the cosmic ray system on Voyager 2 measured significant fluxes of energetic electrons and protons in the regions of the planets magnetosphere where these particles could be stably trapped. The radial distribution of electrons with energies of megaelectron volts is strongly modulated by the sweeping effects ofthe three major inner satellites Miranda, Ariel, and Umbriel. The phase space density gradient of these electrons indicates that they are diffusing radially inward from a source in the outer magnetosphere or magnetotail. Differences in the energy spectra of protons having energies of approximately 1 to 8 megaelectron volts from two different directions indicate a strong dependence on pitch angle. From the locations of the absorption signatures observed in the electron flux, a centered dipole model for the magnetic field of Uranus with a tilt of 60.1 degrees has been derived, and a rotation period of the planet of 17.4 hours has also been calculated. This model provides independent confirmaton of more precise determinations made by other Voyager experiments.

  15. 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.

  16. Solar Energetic Particle Warnings from a Coronagraph

    NASA Technical Reports Server (NTRS)

    St Cyr, O. C.; Posner, A.; Burkepile, J. T.

    2017-01-01

    We report here the concept of using near-real time observations from a coronagraph to provide early warning of a fast coronal mass ejection (CME) and the possible onset of a solar energetic particle (SEP) event. The 1 January 2016, fast CME, and its associated SEP event are cited as an example. The CME was detected by the ground-based K-Cor coronagraph at Mauna Loa Solar Observatory and by the SOHO Large Angle and Spectrometric Coronagraph. The near-real-time availability of the high-cadence K-Cor observations in the low corona leads to an obvious question: Why has no one attempted to use a coronagraph as an early warning device for SEP events? The answer is that the low image cadence and the long latency of existing spaceborne coronagraphs make them valid for archival studies but typically unsuitable for near-real-time forecasting. The January 2016 event provided favorable CME viewing geometry and demonstrated that the primary component of a prototype ground-based system for SEP warnings is available several hours on most days. We discuss how a conceptual CME-based warning system relates to other techniques, including an estimate of the relative SEP warning times, and how such a system might be realized.

  17. 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.

  18. 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.

  19. 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.

  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. Large gradual solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Giacalone, Joe

    2016-09-01

    Solar energetic particles, or SEPs, from suprathermal (few keV) up to relativistic (˜ few GeV) energies are accelerated near the Sun in at least two ways: (1) by magnetic reconnection-driven processes during solar flares resulting in impulsive SEPs, and (2) at fast coronal-mass-ejection-driven shock waves that produce large gradual SEP events. Large gradual SEP events are of particular interest because the accompanying high-energy ({>}10s MeV) protons pose serious radiation threats to human explorers living and working beyond low-Earth orbit and to technological assets such as communications and scientific satellites in space. However, a complete understanding of these large SEP events has eluded us primarily because their properties, as observed in Earth orbit, are smeared due to mixing and contributions from many important physical effects. This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions—NASA's Solar Probe Plus and ESA's Solar Orbiter. Both of these missions are designed to directly and repeatedly sample the near-Sun environments where interplanetary scattering and transport effects are significantly reduced, allowing us to discriminate between different acceleration sites and mechanisms and to isolate the contributions of numerous physical processes occurring during large SEP events.

  2. 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.

  3. 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.

  4. Energetic particles in spherical tokamak plasmas

    NASA Astrophysics Data System (ADS)

    McClements, K. G.; Fredrickson, E. D.

    2017-05-01

    Spherical tokamaks (STs) typically have lower magnetic fields than conventional tokamaks, but similar mass densities. Suprathermal ions with relatively modest energies, in particular beam-injected ions, consequently have speeds close to or exceeding the Alfvén velocity, and can therefore excite a range of Alfvénic instabilities which could be driven by (and affect the behaviour of) fusion α-particles in a burning plasma. STs heated with neutral beams, including the small tight aspect ratio tokamak (START), the mega amp spherical tokamak (MAST), the national spherical torus experiment (NSTX) and Globus-M, have thus provided an opportunity to study toroidal Alfvén eigenmodes (TAEs), together with higher frequency global Alfvén eigenmodes (GAEs) and compressional Alfvén eigenmodes (CAEs), which could affect beam current drive and channel fast ion energy into bulk ions in future devices. In NSTX GAEs were correlated with a degradation of core electron energy confinement. In MAST pulses with reduced magnetic field, CAEs were excited across a wide range of frequencies, extending to the ion cyclotron range, but were suppressed when hydrogen was introduced to the deuterium plasma, apparently due to mode conversion at ion-ion hybrid resonances. At lower frequencies fishbone instabilities caused fast particle redistribution in some MAST and NSTX pulses, but this could be avoided by moving the neutral beam line away from the magnetic axis or by operating the plasma at either high density or elevated safety factor. Fast ion redistribution has been observed during GAE avalanches on NSTX, while in both NSTX and MAST fast ions were transported by saturated kink modes, sawtooth crashes, resonant magnetic perturbations and TAEs. The energy dependence of fast ion redistribution due to both sawteeth and TAEs has been studied in Globus-M. High energy charged fusion products are unconfined in present-day STs, but have been shown in MAST to provide a useful diagnostic of beam ion

  5. Energetic particles in spherical tokamak plasmas

    DOE PAGES

    McClements, K. G.; Fredrickson, E. D.

    2017-03-21

    Spherical tokamaks (STs) typically have lower magnetic fields than conventional tokamaks, but similar mass densities. Suprathermal ions with relatively modest energies, in particular beam-injected ions, consequently have speeds close to or exceeding the Alfvén velocity, and can therefore excite a range of Alfvénic instabilities which could be driven by (and affect the behaviour of) fusion α-particles in a burning plasma. STs heated with neutral beams, including the small tight aspect ratio tokamak (START), the mega amp spherical tokamak (MAST), the national spherical torus experiment (NSTX) and Globus-M, have thus provided an opportunity to study toroidal Alfvén eigenmodes (TAEs), together withmore » higher frequency global Alfvén eigenmodes (GAEs) and compressional Alfvén eigenmodes (CAEs), which could affect beam current drive and channel fast ion energy into bulk ions in future devices. In NSTX GAEs were correlated with a degradation of core electron energy confinement. In MAST pulses with reduced magnetic field, CAEs were excited across a wide range of frequencies, extending to the ion cyclotron range, but were suppressed when hydrogen was introduced to the deuterium plasma, apparently due to mode conversion at ion–ion hybrid resonances. At lower frequencies fishbone instabilities caused fast particle redistribution in some MAST and NSTX pulses, but this could be avoided by moving the neutral beam line away from the magnetic axis or by operating the plasma at either high density or elevated safety factor. Fast ion redistribution has been observed during GAE avalanches on NSTX, while in both NSTX and MAST fast ions were transported by saturated kink modes, sawtooth crashes, resonant magnetic perturbations and TAEs. The energy dependence of fast ion redistribution due to both sawteeth and TAEs has been studied in Globus-M. High energy charged fusion products are unconfined in present-day STs, but have been shown in MAST to provide a useful diagnostic of

  6. Dynamical and energetic instabilities of F = 2 spinor Bose-Einstein condensates in an optical lattice

    NASA Astrophysics Data System (ADS)

    Wang, Deng-Shan; Shi, Yu-Ren; Feng, Wen-Xing; Wen, Lin

    2017-08-01

    The dynamical and energetic instabilities of the F = 2 spinor Bose-Einstein condensates in an optical lattice are investigated theoretically and numerically. By analyzing the dynamical response of different carrier waves to an additional linear perturbation, we obtain the instability criteria for the ferromagnetic, uniaxial nematic, biaxial nematic and cyclic states, respectively. When an external magnetic field is taken into account, we find that the linear or quadratic Zeeman effects obviously affect the dynamical instability properties of uniaxial nematic, biaxial nematic and cyclic states, but not for the ferromagnetic one. In particular, it is found that the faster moving F = 2 spinor BEC has a larger energetic instability region than lower one in all the four states. In addition, it is seen that for most states there probably exists a critical value kc > 0, for which k >kc causes the energetic instability to arise under appreciative parameters.

  7. Solar energetic particle anisotropies and insights into particle transport

    SciTech Connect

    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

    2016-03-25

    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.

  8. 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.

  9. 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.

  10. The role of kinetic effects, including plasma rotation and energetic particles, in resistive wall mode stability

    SciTech Connect

    Berkery, J. W.; Sabbagh, S. A.; Reimerdes, H.; Betti, R.; Hu, B.; Bell, R. E.; Gerhardt, S. P.; Manickam, J.; Podesta, M.

    2010-08-15

    The resistive wall mode (RWM) instability in high-beta tokamaks is stabilized by energy dissipation mechanisms that depend on plasma rotation and kinetic effects. Kinetic modification of ideal stability calculated with the 'MISK' code [B. Hu et al., Phys. Plasmas 12, 057301 (2005)] is outlined. For an advanced scenario ITER [R. Aymar et al., Nucl. Fusion 41, 1301 (2001)] plasma, the present calculation finds that alpha particles are required for RWM stability at presently expected levels of plasma rotation. Kinetic stabilization theory is tested in an experiment in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] that produced marginally stable plasmas with various energetic particle contents. Plasmas with the highest and lowest energetic particle content agree with calculations predicting that increased energetic particle pressure is stabilizing but does not alter the nonmonotonic dependence of stability on plasma rotation due to thermal particle resonances. Presently, the full MISK model, including thermal particles and an isotropic slowing-down distribution function for energetic particles, overpredicts stability in NSTX experiments. Minor alteration of either effect in the theory may yield agreement; several possibilities are discussed.

  11. 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.

  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. 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.

  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. 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.

  16. The effect of solar energetic particles on the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Darwish, Omar Hussain Al; Lillis, Robert; Fillingim, Matthew; Lee, Christina

    2016-10-01

    The precipitation of Solar Energetic Particles (SEP) into the Martian atmosphere causes several effects, one of the most important of which is ionization. However, the importance of this process to the global structure and dynamics for the Martian ionosphere is currently not well understood. The MAVEN spacecraft carries instrumentation which allow us to examine this process. The Neutral Gas and Ion Mass Spectrometer (NGIMS) measures the densities of planetary ions in the Mars ionosphere (O+,CO2+ and O2+). The Solar Energetic Particle (SEP) detector measures the fluxes of energetic protons and electrons. In this project, we examine the degree to which the density of ions in the Martian ionosphere is affected by the precipitation of energetic particles, under conditions of different SEP ion and electron fluxes and at various solar zenith angles. We will present statistical as well as case studies.

  17. Energetic Particles: From Sun to Heliosphere - and vice versa

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, R. F.; Rodriguez-Pacheco, J.; Boden, S.; Boettcher, S. I.; Cernuda, I.; Dresing, N.; Drews, C.; Droege, W.; Elftmann, R.; Espinosa Lara, F.; Gomez-Herrero, R.; Heber, B.; Ho, G. C.; Klassen, A.; Kulkarni, S. R.; Mann, G. J.; Martin-Garcia, C.; Mason, G. M.; Panitzsch, L.; Prieto, M.; Sanchez, S.; Steinhagen, J.; Tammen, J.; Terasa, C.; Yu, J.

    2016-12-01

    Energetic particles in the heliosphere can be measured at their elevated energetic status after three processes: injection, acceleration, and transport. Suprathermal seed particles have speeds well above the fast magnetosonic speed in the solar wind frame of reference and can vary from location to location and within the solar activity cycle. Acceleration sites include reconnecting current sheets in solar flares or magnetspheric boundaries, shocks in the solar corona, heliosphere and a planetary obstacles, as well as planetary magnetospheres. Once accelerated, particles are transported from the acceleration site into and through the heliosphere. Thus, by investigating properties of energetic particles such as their composition, energy spectra, pitch-angle distribution, etc. one can attempt to distinguish their origin or injection and acceleration site. This in turn allows us to better understand transport effects whose underlying microphysics is also a key ingredient in the acceleration of particles. In this presentation we will present some clear examples which link energetic particles from their observing site to their source locations. These include Jupiter electrons, singly-charged He ions from CIRs, and 3He from solar flares. We will compare these examples with the measurement capabilities of the Energetic Particle Detector (EPD) on Solar Orbiter and consider implications for the key science goal of Solar Orbiter and Solar Proble Plus - How the Sun creates and controls the heliosphere.

  18. Current views on impulsive and gradual solar energetic particle events

    NASA Astrophysics Data System (ADS)

    Kallenrode, M.-B.

    2003-05-01

    Solar energetic particles (SEPs) are one manifestation of violent energy releases on the Sun. The study of their acceleration and propagation reveals information about basic plasma-physical processes, such as reconnection, shock acceleration and wave-particle interaction, in astrophysical objects, such as stars, magnetospheres or the diluted plasma of the interstellar or interplanetary medium. This paper introduces the current classification scheme for solar energetic particle events, its relation to the underlying acceleration processes, and addresses open questions regarding the better understanding of SEPs as well as the underlying physical processes. Modifications to the current paradigm considering more recent observations will be suggested.

  19. 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.

  20. Resistance probe for energetic particle dosimetry

    DOEpatents

    Wampler, William R.

    1988-01-01

    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 havinmg an electrical resistance which is related to the number of particles impacting the film, contacts for passing an electrical current through 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.

  1. 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.

  2. Shock Wave Structure in the Presence of Energetic Particles

    NASA Astrophysics Data System (ADS)

    Mostafavi, Parisa; Zank, Gary P.; Webb, Gary M.

    2017-09-01

    Energetic particles that are not equilibrated with the thermal plasma (such as pickup ions (PUIs), anomalous cosmic rays (ACRs) and solar energetic particles (SEPs)) can modify the structure of collisionless shock waves. This is relevant to the inner and outer heliosphere and the Very Local Interstellar Medium (VLISM) where observations of shock waves in the e.g., the inner heliosphere show that the energetic particle component pressure is greater than the both the magnetic field and thermal gas pressure (Lario et al., 2015). Voyager 2 observations revealed that the heliospheric termination shock (HTS) is very broad and mediated by energetic particles. PUIs and SEPs contribute both a collisionless heat flux and a higher-order viscosity. We show that the incorporation of both effects can completely determine the structure of collisionless shocks mediated by energetic ions. Since the reduced form of the PUI mediated plasma model is structurally identical to the classical cosmic ray two-fluid model (Axford et al., (1982)), we note that the presence of viscosity at least formally eliminates the need of a gas sub-shock in the classical two-fluid model, including in that regime where three are possible. By considering parameters upstream of the heliospheric termination shock (HTS), we show that the thermal gas remains relatively cold and the shock is mediated by PUIs. We determine the structure of the weak interstellar shock observed by Voyager 1. We consider the inclusion of the thermal heat flux and viscosity to address the most general form of an energetic particle-thermal plasma two-fluid model.

  3. 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.

  4. Kinetic effects of energetic particles on resistive MHD stability.

    PubMed

    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(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 deltaf 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)10.1063/1.2949704]. It is observed that energetic particles have significant damping and stabilizing effects at experimentally relevant beta, beta(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.

  5. Three-dimensional effects on energetic particle confinement and stability a)

    NASA Astrophysics Data System (ADS)

    Spong, D. A.

    2011-05-01

    Energetic particle populations in magnetic confinement systems are sensitive to symmetry-breaking effects due to their low collisionality and long confined path lengths. Broken symmetry is present to some extent in all toroidal devices. As such effects preclude the existence of an ignorable coordinate, a fully three-dimensional analysis is necessary, beginning with the lowest order (equilibrium) magnetic fields. Three-dimensional techniques that have been extensively developed for stellarator configurations are readily adapted to other devices such as rippled tokamaks and helical states in reversed field pinches. This paper will describe the methods and present an overview of recent examples that use these techniques for the modeling of energetic particle confinement, Alfvén mode structure and fast ion instabilities.

  6. Energetic particle transport in relativistic flows

    NASA Technical Reports Server (NTRS)

    Webb, G. M.

    1992-01-01

    A discussion is given of pitch angle dependent and diffusive transport equations for cosmic rays applicable for both special relativistic and general relativistic flows, derived from the relativistic Boltzmann equation. As an example of particle transport in a curved spacetime we give a pitch angle dependent transport equation appropriate for radial accretion onto a Schwarzschild black hole. The roles of fluid shear, acceleration and compression on the energy changes of particles in the diffusive transport equations are emphasized. Also discussed are special flows (e.g. rigidly rotating flows) associated with a Killing vector for which a constant of the motion of the particles can be identified, and for which simplified transport equations can be constructed.

  7. Nonideal fishbone instability excited by trapped energetic electrons

    SciTech Connect

    Liu, Y.; Tang, C. J.; Wang, Z. T.; Long, Y. X.; Dong, J. Q.

    2013-03-15

    It is shown that trapped energetic electrons can resonate with the collisionless m = 1 nonideal kink mode, therefore exciting the nonideal e-fishbone, which would often lead to a drop in soft x-ray emissivity and frequency chirping. The theory predictions agree well with the experimental observations of e-fishbone on HL-2A. It is also found that the effects of MHD energy of background plasma might be the reason for the observed phenomena: frequency chirping up and down, and V-font-style sweeping.

  8. Nonideal fishbone instability excited by trapped energetic electrons

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Wang, Z. T.; Long, Y. X.; Dong, J. Q.; Tang, C. J.

    2013-03-01

    It is shown that trapped energetic electrons can resonate with the collisionless m = 1 nonideal kink mode, therefore exciting the nonideal e-fishbone, which would often lead to a drop in soft x-ray emissivity and frequency chirping. The theory predictions agree well with the experimental observations of e-fishbone on HL-2A. It is also found that the effects of MHD energy of background plasma might be the reason for the observed phenomena: frequency chirping up and down, and V-font-style sweeping.

  9. Theory of ring sweeping of energetic particles. [in Neptune environment

    NASA Technical Reports Server (NTRS)

    Paranicas, C. P.; Cheng, A. F.

    1991-01-01

    Because the effective 'area' of the Neptunian rings is larger than that of the inner moons, the sweeping of energetic particles by the rings is perhaps the dominant process for particle loss in the magnetosphere within 5 R(N). In this paper, a theory for calculating the absorption probability of energetic charged particles by the rings is described. The effects of a large tilt and an offset between the planet and dipole centers are included. It is found that the probability of absorption for protons is so high that the sweeping lifetime is only a few times the gradient-curvature drift period. For electrons, the sweeping lifetime is even less. The pitch angle dependence for sweeping manifests itself strongly only at large equatorial pitch angles. Lower-energy particles have higher absorption rates by the rings.

  10. 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.

  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. 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.

  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. 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.

  15. 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.

  16. Solar Energetic Particle Precipitation Effects on the ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Lillis, Robert; Larson, Davin; Luhmann, Janet; Lee, Christina; Jakosky, Bruce

    2016-10-01

    Solar Energetic Particles (SEPs) are an important, if irregular, source of ionization and energy input to the Martian atmosphere. As is the case for much-studied Polar Cap precipitation events on the earth, when SEPs precipitate into the Mars atmosphere, they cause heating, ionization, excitation and dissociation, leading to altitude-dependent changes in chemistry. We present a study of the effects of SEP ionization in the Martian atmosphere using data from the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Specifically, we will correlate altitude profiles of thermal planetary ions (O+, CO2+ and O2+) and electrons measured by the Neutral Gas and Ion Mass Spectrometer (NGIMS) and Langmuir Probe on the MAVEN spacecraft with fluxes of energetic protons and electrons measured by the Solar Energetic Particle (SEP) detector. First, we will present case studies of this correlation, before and during SEP events to examine short-term effects of SEP ionization. We will also examine SEP ionization under different heliospheric conditions, leading to different SEP shadowing geometries and ionization rates. Second, we will present a statistical study showing the degree to which ionospheric densities are affected by the presence of energetic particles, as a function of altitude, SEP spectrum flux and solar zenith angle. This work will provide a better understanding of this important source of ionization in the Martian upper atmosphere and hence, how more frequent and more intense SEP events in Mars' past may have affected the structure of the Martian upper atmosphere and hence atmospheric escape.

  17. Studies of modern and ancient solar energetic particles

    SciTech Connect

    Reedy, R.C.

    1998-10-01

    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. Some nuclides 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 are discussed. The SEP average fluxes from both sets of records are similar, and both sets can be used to show that huge fluxes of SEPs are very rare.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Fractional resonances between waves and energetic particles in tokamak plasmas.

    PubMed

    Kramer, G J; Chen, L; Fisher, R K; Heidbrink, W W; Nazikian, R; Pace, D C; Van Zeeland, M A

    2012-07-20

    From numerical simulation and analytical modeling it is shown that fast ions can resonate with plasma waves at fractional values of the particle drift-orbit transit frequency when the plasma wave amplitude is sufficiently large. The fractional resonances, which are caused by a nonlinear interaction between the particle orbit and the wave, give rise to an increased density of resonances in phase space which reduces the threshold for stochastic transport. The effects of the fractional resonances on spatial and energy transport are illustrated for an energetic particle geodesic acoustic mode but they apply equally well to other types of MHD activity.

  3. Magnetic field models from energetic particle data at Neptune

    NASA Technical Reports Server (NTRS)

    Selesnick, R. S.

    1992-01-01

    The locations of features in the Voyager 2 energetic particle data from Neptune are combined with uncertainties in the multipole expansion of the planetary magnetic field to derive new magnetic field models that are consistent both with various interpretations of the particle features and with the magnetic field data. While assumptions as to the origin of the features must be made, they do not provide sufficient constraints to obtain significant new information on any of the unknown multipole coefficients. However, the magnetic L shell positions of the particle features, which are interpreted primarily as absorption signatures of Neptune's satellites, can, in general, be brought into agreement with expected values.

  4. Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

    SciTech Connect

    Toi, K.; Ogawa, K.; Isobe, M.; Osakabe, M.; Spong, Donald A; Todo, Yasushi

    2011-01-01

    Comprehensive understanding of energetic-ion-driven global instabilities such as Alfven eigenmodes (AEs) and their impact on energetic ions and bulk plasma is crucially important for tokamak and stellarator/helical plasmas and in the future for deuterium-tritium (DT) burning plasma experiments. Various types of global modes and their associated enhanced energetic ion transport are commonly observed in toroidal plasmas. Toroidicity-induced AEs and ellipticity-induced AEs, whose gaps are generated through poloidal mode coupling, are observed in both tokamak and stellarator/helical plasmas. Global AEs and reversed shear AEs, where toroidal couplings are not as dominant were also observed in those plasmas. Helicity induced AEs that exist only in 3D plasmas are observed in the large helical device (LHD) and Wendelstein 7 Advanced Stellarator plasmas. In addition, the geodesic acoustic mode that comes from plasma compressibility is destabilized by energetic ions in both tokamak and LHD plasmas. Nonlinear interaction of these modes and their influence on the confinement of the bulk plasma as well as energetic ions are observed in both plasmas. In this paper, the similarities and differences in these instabilities and their consequences for tokamak and stellarator/helical plasmas are summarized through comparison with the data sets obtained in LHD. In particular, this paper focuses on the differences caused by the rotational transform profile and the 2D or 3D geometrical structure of the plasma equilibrium. Important issues left for future study are listed.

  5. Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Toi, K.; Ogawa, K.; Isobe, M.; Osakabe, M.; Spong, D. A.; Todo, Y.

    2011-02-01

    Comprehensive understanding of energetic-ion-driven global instabilities such as Alfvén eigenmodes (AEs) and their impact on energetic ions and bulk plasma is crucially important for tokamak and stellarator/helical plasmas and in the future for deuterium-tritium (DT) burning plasma experiments. Various types of global modes and their associated enhanced energetic ion transport are commonly observed in toroidal plasmas. Toroidicity-induced AEs and ellipticity-induced AEs, whose gaps are generated through poloidal mode coupling, are observed in both tokamak and stellarator/helical plasmas. Global AEs and reversed shear AEs, where toroidal couplings are not as dominant were also observed in those plasmas. Helicity induced AEs that exist only in 3D plasmas are observed in the large helical device (LHD) and Wendelstein 7 Advanced Stellarator plasmas. In addition, the geodesic acoustic mode that comes from plasma compressibility is destabilized by energetic ions in both tokamak and LHD plasmas. Nonlinear interaction of these modes and their influence on the confinement of the bulk plasma as well as energetic ions are observed in both plasmas. In this paper, the similarities and differences in these instabilities and their consequences for tokamak and stellarator/helical plasmas are summarized through comparison with the data sets obtained in LHD. In particular, this paper focuses on the differences caused by the rotational transform profile and the 2D or 3D geometrical structure of the plasma equilibrium. Important issues left for future study are listed.

  6. Energetic Particle Transport in Strong Compressive Wave Turbulence Near Shocks

    SciTech Connect

    Le Roux, J.A.; Zank, G.P.; Li, G.; Webb, G.M.

    2005-08-01

    Strong interplanetary coronal mass ejection driven shocks are often accompanied by high levels of low frequency compressive wave turbulence. This might require a non-linear kinetic theory approach to properly describe energetic particle transport in their vicinity. We present a non-linear diffusive kinetic theory for suprathermal particle transport and stochastic acceleration along the background magnetic field in strong compressive dynamic wave turbulence to which small-scale Alfven waves are coupled. Our theory shows that the standard cosmic-ray transport equation must be revised for low suprathermal particle energies to accommodate fundamental changes in spatial diffusion (standard diffusion becomes turbulent diffusion) as well as modifications to particle convection, and adiabatic energy changes. In addition, a momentum diffusion term, which generates accelerated suprathermal particle spectra with a hard power law, must be added. Such effective first stage acceleration possibly leads to efficient injection of particles into second stage diffusive shock acceleration as described by standard theory.

  7. 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.

  8. An overview of the energetic electron induced instabilities with high-power ECRH on HL-2A

    NASA Astrophysics Data System (ADS)

    Ding, X. T.; Chen, W.; Yu, L. M.; Chen, S. Y.; Dong, J. Q.; Ji, X. Q.; Shi, Z. B.; Zhou, Y.; Dong, Y. B.; Huang, X. L.; Li, J. X.; Zhang, Y. P.; Song, X. Y.; Song, X. M.; Zhou, J.; Rao, J.; Cao, J. Y.; Huang, M.; Feng, B. B.; Cui, Z. Y.; Huang, Y.; Liu, Yi.; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Liu, Y.

    2013-04-01

    In this paper, an overview of the magnetohydrodynamic instabilities induced by energetic electrons on HL-2A is given and some new phenomena with high-power electron cyclotron resonance heating (ECRH) are presented. A toroidal Alfvén eigenmode with frequency from 200 to 350 kHz is identified during powerful ECRH. In the lower frequency range from 10 to 35 kHz, which is in the beta-induced Alfvén eigenmode frequency range, the coexistence of multi-mode is found during the high-power ECRH for the first time. The spectra become wide when the power is sufficiently high. The frequencies of the modes increase with and are much lower than the Alfvén frequency. The relationship between the mode frequency and (7/4 + Te/Ti)1/2 (Ti)1/2 can be obtained by statistical data analysis. Between the two previous frequency ranges, a group of new modes with frequencies from 50 to 180 kHz is observed with high-power ECRH and neutral beam injection heating together. The modes have clear frequency chirping within several milliseconds or several tens of milliseconds, which are identified as energetic particle mode like instabilities. The new features of the fishbone instability excited by energetic electrons are identified. It is interesting to find the frequency jump phenomena in the high-power ECRH. The difference between the low and high frequencies increases with ECRH power. The frequency jumps between 8 and 15 kHz within about 25 ms periodically, when the power is 1.2 MW.

  9. On resonant destabilization of toroidal Alfven eigenmodes by circulating and trapped energetic ions/alpha particles in tokamaks

    SciTech Connect

    Biglari, H.; Zonca, F.; Chen, L.

    1991-10-01

    Toroidal Alfven eigenmodes are shown to be resonantly destabilized by both circulating and trapped energetic ions/alpha particles. In particular, the energetic circulating ions are shown to resonate with the mode not only at the Alfven speed ({upsilon}{sub A}), but also one-third of this speed, while resonances exist between trapped energetic ions and the wave when {upsilon} = {upsilon}{sub A}/21{epsilon}{sup {1/2}} (l=integer, {epsilon}=r/R is the local inverse aspect ratio), although the instability becomes weaker for resonances other than the fundamental. The oft-quoted criterion that instability requires super-Alfvenic ion velocities is thus sufficient but not necessary. 14 refs.

  10. High Latitude Energetic Particle Boundaries: The SAMPEX Database

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.

    2006-11-01

    The size of the polar cap or the open field line region depends, upon the difference in reconnection rates at the dayside between the IMF and the geomagnetic field, and those occurring in the magnetotail. The dayside merging adds flux to the open field region increasing the polar cap size and the magnetic flux in the lobes of the tail, thereby causing energy to be stored in the magnetosphere. Night side reconnection, geomagnetic storms and substorms dissipate this energy removing flux and shrink the polar cap. The dynamics of the polar cap can therefore be useful in the study of the energy dynamics of the magnetosphere. Energetic particles delineate magnetospheric regions, since their motions are governed by the geomagnetic field. Convection and corotation electric fields control the drift of low energy particles whereas magnetic field gradient and curvature are the dominant factors for higher energy (> ~30 keV) particles. High latitude energetic particle boundaries are related to the polar cap and therefore useful in determining the size of the open field line regions We will provide a long database of energetic particle boundaries in the polar regions using instruments aboard SAMPEX, the first of the Small explorer (SMEX) spacecraft. It was launched on July 3, 1992 into a low earth polar orbit. There are four particle detectors, HILT, LICA, PET and MAST on board which point toward the zenith over the poles of the Earth. These detectors measure electrons, protons and ions ranging in energy from tens of keV to a few MeV. This database will comprise the latitudinal (geographic, magnetic and invariant) and longitudinal (geographic and magnetic local time) positions of energetic particle boundaries in the polar regions. The database will cover a time period from launch to about mid 2004. It will therefore cover a significant portion of the solar cycles 22 and 23. Together with interplanetary data obtainable from public databases, such as the NASA OMNI database the

  11. 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.

  12. Atmospheric cosmic rays and solar energetic particles at aircraft altitudes.

    PubMed

    O'Brien, K; Friedberg, W; Sauer, H H; Smart, D F

    1996-01-01

    Galactic cosmic rays, which are thought to be produced and accelerated by a variety of mechanisms in the Milky Way galaxy, interact with the solar wind, the earth's magnetic field, and its atmosphere to produce hadron, lepton, and photon fields at aircraft altitudes that are quite unlike anything produced in the laboratory. The energy spectra of these secondary particles extend from the lowest possible energy to energies over an EeV. In addition to cosmic rays, energetic particles, generated on the sun by solar flares or coronal mass ejections, bombard the earth from time to time. These particles, while less energetic than cosmic rays, also produce radiation fields at aircraft altitudes which have qualitatively the same properties as cosmic rays. The authors have calculated atmospheric cosmic-ray angular fluxes, spectra, scalar fluxes, and ionization, and compared them with experimental data. Agreement with these data is seen to be good. These data have been used to calculate equivalent doses in a simplified human phantom at aircraft altitudes and the estimated health risks to aircraft crews. The authors have also calculated the radiation doses from several large solar energetic particle events (known as GLEs, or Ground Level Events), which took place in 1989, including the very large event known as GLE 42, which took place on September 29th and 30th of that year. The spectra incident on the atmosphere were determined assuming diffusive shock theory. Unfortunately, there are essentially no experimental data with which to compare these calculations.

  13. New Energetic Particle Data and Products from the GOES Program

    NASA Astrophysics Data System (ADS)

    Onsager, Terrance; Rodriguez, Juan

    The NOAA Geostationary Operational Environmental Satellite (GOES) program has provided continuous, real-time measurements of the near-Earth space environment for decades. In addition to their scientific value, the GOES energetic particle measurements are the basis for a variety of space weather products and services, including the forecasting of elevated energetic particle levels, real-time knowledge of the satellite environment at geostationary orbit, and data to allow post-event analyses when satellite anomalies occur. The GOES satellites have traditionally provided measurements of high-energy electrons, protons, and alpha particles (100s of keV to 100s of MeV). Beginning with the launch of GOES-13 in 2006, the measurement capabilities were expanded to include medium-energy electrons and protons (10s to 100s of keV) with pitch angle resolution. The next generation of GOES satellites, starting with GOES-R in 2016, will include low-energy electrons and ions (10s of eV to 10s of keV) as well as energetic heavy ions. In this presentation, we will overview the GOES particle measurements available now and in the future and describe the space weather services and scientific investigations that these data support.

  14. The Energetic Particle Investigation for the SMART Magnetospheric Multiscale Mission

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.; Baker, D. N.; Blake, J. B.; Clemmons, J. H.; Livi, S.; Reeves, G. D.; Spence, H. E.

    2005-12-01

    The Solving Magnetospheric Acceleration, Reconnection, and Turbulence (SMART) payload investigation, selected by NASA for the Magnetospheric Multiscale (MMS) mission, has as its primary goal to investigate the causes and consequences of the magnetic reconnection in magnetized plasmas by making measurements within and at the boundaries of the Earth's magnetosphere. The SMART Energetic Particle Detector (EPD) investigation supports the MMS investigation of reconnection by: 1) Remotely sensing and measuring the positions and speeds of boundaries and other structures, 2) Sensing magnetic topology, 3) Remotely sensing acceleration sites; and 4) Determining the causes of energization and phase space density modifications of energetic electrons and ions. The EPD consists of two sensor types. The Flys Eye Energetic Particle Spectrometer (FEEPS) measures fast, all-sky electron spectra simultaneously from 18 different directions over the energy range of about 20 keV to 1 MeV, and it measures total ion spectra simultaneously from 6 different directions over two fan shaped fields-of-view. The Energetic Ion Spectrometer (EIS) measures ion energy spectra and composition (H and O) over 6 different directions within a fan-shaped field of view. Combined FEEPS and EIS ion measurements deliver all-sky ion measurement over the energy range of about 20 keV to 1 MeV. In this presentation we describe the EPD sensors and investigation and show how closure on the investigation goals is achieved.

  15. 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.

  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. Energetic particles in laboratory, space and astrophysical plasmas

    NASA Astrophysics Data System (ADS)

    McClements, K. G.; Turnyanskiy, M. R.

    2017-01-01

    Some recent studies of energetic particles in laboratory, space and astrophysical plasmas are discussed, and a number of common themes identified. Such comparative studies can elucidate the underlying physical processes. For example microwave bursts observed during edge localised modes (ELMs) in the mega amp spherical tokamak (MAST) can be attributed to energetic electrons accelerated by parallel electric fields associated with the ELMs. The very large numbers of electrons known to be accelerated in solar flares must also arise from parallel electric fields, and the demonstration of energetic electron production during ELMs suggests close links at the kinetic level between ELMs and flares. Energetic particle studies in solar flares have focussed largely on electrons rather than ions, since bremsstrahlung from deka-keV electrons provides the best available explanation of flare hard x-ray emission. However ion acceleration (but not electron acceleration) has been observed during merging startup of plasmas in MAST with dimensionless parameters similar to those of the solar corona during flares. Recent measurements in the Earth’s radiation belts demonstrate clearly a direct link between ion cyclotron emission (ICE) and fast particle population inversion, supporting the hypothesis that ICE in tokamaks is driven by fast particle distributions of this type. Shear Alfvén waves in plasmas with beta less than the electron to ion mass ratio have a parallel electric field that, in the solar corona, could accelerate electrons to hard x-ray-emitting energies; an extension of this calculation to plasmas with Alfvén speed arbitrarily close to the speed of light suggests that the mechanism could play a role in the production of cosmic ray electrons.

  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. 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.

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

    PubMed

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

    1975-05-02

    Knowledge of the positional distributions, absolute intensities, energy spectra, and angular distributions of energetic electrons and protons in the Jovian magnetosphere has been considerably advanced by the planetary flyby of Pioneer 11 in November-December 1974 along a quite different trajectory from that of Pioneer 10 a year earlier. (i) The previously reported magnetodisc is shown to be blunted and much more extended in latitude on the sunward side than on the dawn side. (ii) Rigid corotation of the population of protons E(p) approximately 1 million electron volts in the magnetodisc is confirmed. (iii) Angular distributions of energetic electrons E(e) > 21 million electron volts in the inner magnetosphere are shown to be compatible with the Kennel-Petschek whistler-mode instability. (iv) A diverse body of magnetospheric effects by the Jovian satellites is found. (v) Observations of energetic electrons in to a radial distance of 1.59 Jovian radii provide a fresh basis for the interpretation of decimetric radio noise emission.

  2. A Guided Tour of Heliospheric Waves, Shocks and Energetic Particles

    NASA Astrophysics Data System (ADS)

    Lee, M. A.

    2008-05-01

    This Parker Lecture is a personal guided tour through the heliosphere featuring hydromagnetic waves, shocks, and energetic particle populations, their observed behavior from the Sun to the solar wind termination shock, and the theoretical concepts that have been developed to describe them. As a first-year graduate student, I first met Gene Parker in January 1967 when he was my instructor in Electrodynamics at the University of Chicago. His contributions to our understanding of heliospheric waves, shocks, and energetic particles over the last 50 years have molded our view of these diverse but connected heliospheric phenomena. I shall mention those contributions that have been particularly influential in my own work. The tour will include, for example, stops at Earth's bow shock, the shocks bounding corotating interaction regions in the solar wind, the solar wind termination shock, the space environment around comets, the mass and momentum loading of the solar wind through its interaction with the interstellar gas, the theory of diffusive shock acceleration, and the process of stochastic acceleration. The lecture will end with a list of outstanding puzzles concerning energetic particle transport and shock structure for which we seek solutions as we complete Voyagers' exploration of the outer heliosphere and start to explore the inner neighborhood of the Sun.

  3. Modified Budden problem associated with energetic particles in fusion plasmas

    NASA Astrophysics Data System (ADS)

    Brizard, Alain; Kaufman, Allan; Tracy, Eugene; Jaun, Andre

    2006-10-01

    The classic Budden problem is a double-conversion process, whereby a primary incoming wave is converted to a localized secondary wave which then converts to an outgoing (reflected) primary wave. Using ray phase-space methods [1], we investigate the modification of the Budden problem associated with the presence of a localized tertiary wave supported by an energetic-particle population in an inhomogeneous magnetized plasma. The calculation of the reflection coefficient for this modified Budden problem is based on a simple one-dimensional model where the tertiary wave is parameterized by the energetic-particle density and its separation from the localized secondary wave. Note that, since an energetic-particle population can support waves of either positive or negative energy, interference effects are taken into account for each case by using a modular-eikonal approach [2]. [1] E.R. Tracy, A.N. Kaufman, and A.J. Brizard, Phys. Plasmas 10, 2147 (2003). [2] A.J. Brizard, J.J. Morehead, A.N. Kaufman, and E.R. Tracy, Phys. Plasmas 5, 45 (1998).

  4. Solar energetic particle events: Statistical modelling and prediction

    NASA Technical Reports Server (NTRS)

    Gabriel, S. B.; Feynman, J.; Spitale, G.

    1996-01-01

    Solar energetic particle events (SEPEs) can have a significant effect on the design and operation of earth orbiting and interplanetary spacecraft. In relation to this, the calculation of proton fluences and fluxes are considered, describing the current state of the art in statistical modeling. A statistical model that can be used for the estimation of integrated proton fluences for different mission durations of greater than one year is reviewed. The gaps in the modeling capabilities of the SEPE environment, such as a proton flux model, alpha particle and heavy ion models and solar cycle variations are described together with the prospects for the prediction of events using neural networks.

  5. The magnetosphere of Neptune - Hot plasmas and energetic particles

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Keath, E. P.; Kane, M.; Krimigis, M.; Cheng, A. F.; Acuna, M. H.; Armstrong, T. P.; Ness, N. F.

    1991-01-01

    An overview is presented of the hot plasmas and energetic (not less than 20 keV) particles observed in the vicinity of Neptune by the Low Energy Charged Particle (LECP) experiment aboard the Voyager 2 spacecraft. The LECP findings are presented on the shock, the magnetosheath, the magnetopause, and the cusp of the Neptune's magnetosphere; the middle magnetosphere; the inner magnetosphere and material interactions; the magnetotail and the substorms; and the characteristics of Triton's plasma. It is shown that, in sharp contrast to the Uranian magnetotail, the Neptunian magnetotail shows no evidence of substorm processes.

  6. Effect of Trapped Energetic Particles on the Resistive Wall Mode

    SciTech Connect

    Hao, G. Z.; Wang, A. K.; Qiu, X. M.; Liu, Y. Q.

    2011-07-01

    A stability analysis for the resistive wall mode is studied in the presence of trapped energetic particles (EPs). When the EPs' beta exceeds a critical value, a fishbonelike bursting mode (FLM) with an external kink eigenstructure can exist. This offers the first analytic interpretation of the experimental observations [Phys. Rev. Lett. 103, 045001 (2009)]. The mode-particle resonances for the FLM and the q=1 fishbone occur in different regimes of the precession frequency of EPs. In certain ranges of the plasma rotation speed and the EPs' beta, a mode conversion can occur between the resistive wall mode and FLM.

  7. 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.

  8. 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.

  9. Effects of ULF waves on local and global energetic particles: Particle energy and species dependences

    NASA Astrophysics Data System (ADS)

    Li, L. Y.; Yu, J.; Cao, J. B.; Wang, Z. Q.; Yu, Y. Q.; Reeves, G. D.; Li, X.

    2016-11-01

    After 06:13 UT on 24 August 2005, an interplanetary shock triggers large-amplitude ultralow-frequency (ULF) waves (|δB| ≥ 15 nT) in the Pc4-Pc5 wave band (1.6-9 mHz) near the noon geosynchronous orbit (6.6 RE). The local and global effects of ULF waves on energetic particles are observed by five Los Alamos National Laboratory satellites at different magnetic local times. The large-amplitude ULF waves cause the synchronous oscillations of energetic electrons and protons (≥75 keV) at the noon geosynchronous orbit. When the energetic particles have a negative phase space density radial gradient, they undergo rapid outward radial diffusion and loss in the wave activity region. In the particle drift paths without strong ULF waves, only the rapidly drifting energetic electrons (≥225 keV) display energy-dispersive oscillations and flux decays, whereas the slowly drifting electrons (<225 keV) and protons (75-400 keV) have no ULF oscillation and loss feature. When the dayside magnetopause is compressed to the geosynchronous orbit, most of energetic electrons and protons are rapidly lost because of open drift trajectories. The global and multicomposition particle measurements demonstrate that the effect of ULF waves on nonlocal particle flux depends on the particle energy and species, whereas magnetopause shadowing effect is independent of the energetic particle species. For the rapidly drifting outer radiation belt particles (≥225 keV), nonlocal particle loss/acceleration processes could also change their fluxes in the entire drift trajectory in the absence of "Dst effect" and substorm injection.

  10. ENERGETIC PARTICLE PRESSURE AT INTERPLANETARY SHOCKS: STEREO-A OBSERVATIONS

    SciTech Connect

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

    2015-11-10

    We study periods of elevated energetic particle intensities observed by STEREO-A when the partial pressure exerted by energetic (≥83 keV) protons (P{sub EP}) is larger than the pressure exerted by the interplanetary magnetic field (P{sub B}). In the majority of cases, these periods are associated with the passage of interplanetary shocks. Periods when P{sub EP} exceeds P{sub B} 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, P{sub EP} also exceeds the pressure exerted by the solar wind thermal population (P{sub TH}). Prolonged periods (>12 hr) with both P{sub EP} > P{sub B} and P{sub EP} > P{sub TH} 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 P{sub SUM} = P{sub B} + P{sub TH} + P{sub EP} are observed in the immediate upstream region of the shocks regardless of individual changes in P{sub EP}, P{sub B}, and P{sub TH}, indicating a coupling between P{sub EP} and the pressure of the background medium characterized by P{sub B} and P{sub TH}. The quasi-exponential increase of P{sub SUM} implies a radial gradient ∂P{sub SUM}/∂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.

  11. 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.

  12. 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.

  13. Properties of energetic-particle continuum modes destabilized by energetic ions with beam-like velocity distributions

    SciTech Connect

    Todo, Y.

    2006-08-15

    Properties of energetic-particle continuum modes (EPMs) destabilized by energetic ions in tokamak plasmas were investigated using a hybrid simulation code for magnetohydrodynamics and energetic particles. The energetic ions are assumed to have beam-like velocity distributions for the purpose of clarifying the dependence on energetic ion velocity. It was found that for beam velocities lower than the Alfven velocity, the unstable modes are EPMs while the toroidal Alfven eigenmodes are unstable for the beam velocities well above the Alfven velocity. The EPMs destabilized by the copassing energetic ions and those destabilized by the counterpassing energetic ions differ in primary poloidal harmonics and spatial locations. The frequencies of the EPMs are located close to the shear Alfven continuous spectrum when they are compared at the spatial peak locations of the primary poloidal harmonic or compared at the spatial tails if the primary poloidal harmonic is m=1. The frequencies of the EPMs were carefully compared with the energetic-ion orbital frequencies. It was found that the frequencies of the EPMs are in good agreement with the energetic-ion orbital frequencies with a correction for the toroidal circulation frequency. This demonstrates that the energetic-ion orbital frequency determines the EPM frequency.

  14. 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.

  15. SIMULATIONS OF ENERGETIC PARTICLES INTERACTING WITH DYNAMICAL MAGNETIC TURBULENCE

    SciTech Connect

    Hussein, M.; Shalchi, A. E-mail: husseinm@myumanitoba.ca

    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/B{sub 0} = 0.5.

  16. 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.

  17. Understanding the Acceleration of Energetic Particles at the Termination Shock

    NASA Astrophysics Data System (ADS)

    Gloeckler, G.; Fisk, L. A.

    2006-05-01

    Voyager 1 observations of energetic particles during the crossing of the Termination Shock of the solar wind present a number of puzzles, and challenges to existing acceleration theories. For example, downstream from the shock the low-energy phase space density spectra are power laws exhibiting a remarkably constant spectral index, which is difficult to understand in terms of standard diffusive shock acceleration. Upstream from the shock there are beams of highly anisotropic energetic particles, with varying spectral shapes. Again, diffusive shock acceleration has difficultly in dealing with such large anisotropies. Here we show that the observed, constant spectral index of -5 can be accounted for by a simple theory in which the pressure in the accelerated particles behaves according to the Rankine-Hugoniot relationship of an ideal gas at the shock. We also demonstrate that the observed varying spectral shapes of the upstream beams result from velocity dispersion of a downstream spectrum with index of -5 propagating along magnetic flux tubes connecting the termination shock to Voyager 1. We show that even though the beams dominate the upstream foreshock region, they do not have an appreciable effect on the shock acceleration process. The implications of our theory for the acceleration of the Anomalous Cosmic Rays in the heliosheath are also discussed.

  18. Shock parameters and energetic storm particle events using STEREO spacecraft

    NASA Astrophysics Data System (ADS)

    Preisser, Luis; Blanco-Cano, Xochitl; Kajdic, Primoz

    2017-04-01

    Solar Energetic Particles (SEPs) propagate across the interplanetary space with energies of the order of MeVs. These events can be classified as impulsive or gradual depending mainly on the duration of the enhancement of the flux spectra profile. While impulsive events (with durations of the order of hours) are associated with particle acceleration in flares, gradual events (with durations of the order of various days) are associated with acceleration produced by the Interplanetary Coronal Mass Ejection (ICME) driven shocks. Further the flux spectra signature for the gradual SEPs has been associated with the magnetic connectivity of the CME relative to the spacecraft. In this work we studied the so called Energetic Storm Particle (ESP) events: SEP events with an additional enhancement in the flux spectra near the shock crossing time, interpreted as additional flux due to the diffusive shock acceleration inside the shock region. We use for our analysis the ESP events observed with both STEREO spacecraft during the period 2011-2014 in order to study their characteristics and relate them to the parameters of the shocks that are thought to produce them.

  19. 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.

  20. The "Puck" Energetic Charged Particle Detector: Design, Heritage, and Advancements

    NASA Technical Reports Server (NTRS)

    Clark, G.; Cohen, I.; Westlake, J. H.; Andrews, G. B.; Brandt, P.; Gold, R. E.; Gkioulidou, M. A.; Hacala, R.; Haggerty, D.; Hill, M. E.; hide

    2016-01-01

    Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of approximately 10 kiloelectronvolts to several megaelectronvolts. This sensor makes simultaneous angular measurements of electron fluxes from the tens of kiloelectronvolts to about 1 megaelectronvolt. The same measurements can be extended down to approximately 1 kiloelectronvolt per nucleon,with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

  1. The "Puck" energetic charged particle detector: Design, heritage, and advancements

    NASA Astrophysics Data System (ADS)

    Clark, G.; Cohen, I.; Westlake, J. H.; Andrews, G. B.; Brandt, P.; Gold, R. E.; Gkioulidou, M. A.; Hacala, R.; Haggerty, D.; Hill, M. E.; Ho, G. C.; Jaskulek, S. E.; Kollmann, P.; Mauk, B. H.; McNutt, R. L.; Mitchell, D. G.; Nelson, K. S.; Paranicas, C.; Paschalidis, N.; Schlemm, C. E.

    2016-08-01

    Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of ~10 keV to several MeV. This sensor makes simultaneous angular measurements of electron fluxes from the tens of keV to about 1 MeV. The same measurements can be extended down to approximately 1 keV/nucleon, with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

  2. The "Puck" Energetic Charged Particle Detector: Design, Heritage, and Advancements

    NASA Technical Reports Server (NTRS)

    Clark, G.; Cohen, I.; Westlake, J. H.; Andrews, G. B.; Brandt, P.; Gold, R. E.; Gkioulidou, M. A.; Hacala, R.; Haggerty, D.; Hill, M. E.; Ho, G. C.; Jaskulek, S. E.; Kollmann, P.; Mauk, B. H.; McNutt, R. L., Jr.; Mitchell, D. G.; Nelson, K. S.; Paranicas, C.; Paschalidis, N.; Schlemm, C. E.

    2016-01-01

    Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of approximately 10 kiloelectronvolts to several megaelectronvolts. This sensor makes simultaneous angular measurements of electron fluxes from the tens of kiloelectronvolts to about 1 megaelectronvolt. The same measurements can be extended down to approximately 1 kiloelectronvolt per nucleon,with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

  3. The "Puck" energetic charged particle detector: Design, heritage, and advancements.

    PubMed

    Clark, G; Cohen, I; Westlake, J H; Andrews, G B; Brandt, P; Gold, R E; Gkioulidou, M A; Hacala, R; Haggerty, D; Hill, M E; Ho, G C; Jaskulek, S E; Kollmann, P; Mauk, B H; McNutt, R L; Mitchell, D G; Nelson, K S; Paranicas, C; Paschalidis, N; Schlemm, C E

    2016-08-01

    Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of ~10 keV to several MeV. This sensor makes simultaneous angular measurements of electron fluxes from the tens of keV to about 1 MeV. The same measurements can be extended down to approximately 1 keV/nucleon, with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

  4. Energetic particle sounding at the magnetopause and implications for magnetic reconnection

    NASA Technical Reports Server (NTRS)

    Fritz, T. A.; Williams, D. J.

    1984-01-01

    Measurements of energetic particle three dimensional distributions used to infer the structure of the region of the subsolar magnetopause obtained from the Medium Energy Particle Experiment onboard the ISEE-1 and 2 satellites are reviewed. Although initial interpretations of two types of energetic particle signatures argued against the topology predicted by magnetic reconnection at the magnetopause, subsequent understanding of the meaning of these observations demonstrate that the energetic particle data are uniformly consistent with the theory.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Experimental investigation of the radial structure of energetic particle driven modes

    NASA Astrophysics Data System (ADS)

    Horváth, L.; Papp, G.; Lauber, Ph.; Por, G.; Gude, A.; Igochine, V.; Geiger, B.; Maraschek, M.; Guimarais, L.; Nikolaeva, V.; Pokol, G. I.; the ASDEX Upgrade Team

    2016-11-01

    Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) are often excited by energetic particles (EPs) in tokamak plasmas. One of the main open questions concerning EP driven instabilities is the non-linear evolution of the mode structure. The aim of the present paper is to investigate the properties of beta-induced AEs (BAEs) and EP driven geodesic acoustic modes (EGAMs) observed in the ramp-up phase of off-axis NBI heated ASDEX Upgrade (AUG) discharges. This paper focuses on the changes in the mode structure of BAEs/EGAMs during the non-linear chirping phase. Our investigation has shown that in the case of the observed down-chirping BAEs the changes in the radial structure are smaller than the uncertainty of our measurement. This behaviour is most probably the consequence of the fact that BAEs are normal modes, thus their radial structure strongly depends on the background plasma parameters rather than on the EP distribution. In the case of rapidly upward chirping EGAMs the analysis consistently shows shrinkage of the mode structure. The proposed explanation is that the resonance in the velocity space moves towards more passing particles which have narrower orbit widths.

  11. Energetic Particle Data From the Global Positioning System Constellation: GPS ENERGETIC PARTICLE DATA

    DOE PAGES

    Morley, S. K.; Sullivan, J. P.; Carver, M. R.; ...

    2017-02-01

    Since 2000, Los Alamos National Laboratory (LANL) Combined X-ray and Dosimeter (CXD) and Burst Detector Dosimeter for Block II-R (BDD-IIR) instruments have been fielded on Global Positioning System (GPS) satellites. Today, 21 of the 31 operational GPS satellites are equipped with a CXD detector and a further 2 carry a BDD-IIR. Each of these instruments measures a wide range of energetic electrons and protons. These data have now been publicly released under the terms of the Executive Order for Coordinating Efforts to Prepare the Nation for Space Weather Events. The specific goal of releasing space weather data from the GPSmore » satellites is to enable broad scientific community engagement in enhancing space weather model validation and improvements in space weather forecasting and situational awareness. The time period covered by this data release is approximately 16 years, which corresponds to more than 167 satellite years of data. As a result, the large number of GPS satellites, distributed over six orbital planes, will provide important context for ongoing and historical science missions, as well as enabling new types of research not previously possible.« less

  12. A statistical study of plasmawaves and energetic particles in the outer magnetosphere

    NASA Astrophysics Data System (ADS)

    Min, Kyungguk

    The Earth magnetosphere contains energetic particles undergoing specific motions around Earth's magnetic field, and interacting with a variety of waves. The dynamics of energetic particles are often described in terms of three kinds of adiabatic invariants. Energetic electrons are often unstable to the whistler-mode chorus waves, and ions, to the electromagnetic ion cyclotron (EMIC) instability. These waves play an important role in the dynamics of the magnetosphere by energizing electrons to form a radiation belt, extracting energy from the hot, anisotropic ions and causing pitch angle scattering of energetic ions and relativistic electrons into the loss cone. EMIC waves correspond to the highest frequency waves in the ultra-low frequency (ULF) spectral regime, and field line resonances at the lower frequency may serve as diagnostics for the plasma distribution in the magnetosphere. This dissertation investigates (1) a rapid, efficient way of specifying particle's adiabatic motion in the magnetosphere, (2) source of the whistler-mode chorus waves, (3) physical properties and coherent spatial dimensions of the EMIC waves and (4) a diagnostic use of the toroidal mode Alfven waves on the plasma density distribution in the Earth magnetosphere. The studies presented in this dissertation have significantly been benefited from the comprehensive data obtained by several space missions, including the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft, Cluster mission, the Geostationary Operational Environment Satellites (GOES), Los Alamos National Laboratory (LANL) satellites, the Polar spacecraft and the Active Magnetospheric Particle Tracer Explorers (AMPTE)/Charge Composition Explorer (CCE), and from ground-based Automatic Geophysical Observatories (AGO). The main findings and achievements in this dissertation are as follows: (1) A method of rapidly and efficiently computing the magnetic drift invariant (L*) was developed. This new

  13. Particle Acceleration in Relativistic Jets Due to Weibel Instability

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

    2004-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  14. Particle Acceleration in Relativistic Jets due to Weibel Instability

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

    2003-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The jitter radiation (Medvedev 2000) from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  15. Particle accelerations and current structures of Weibel and Filamentation instabilities

    NASA Astrophysics Data System (ADS)

    Ryu, C. M.; Huynh, C. T.

    2015-12-01

    Particle accelerations of the Wibel instability (WI) and the Filamentation instability(FI) are studied by using PIC simuations, comparing them side-by-side. Although two instabilities are almost identical in the linear growth phase, significant differences are found in the nonlinear phase in their particle accelerations and current structures. The FI shows enhanced electron acceleration, whereas particle acceleration is almost absent in the WI. The different particle accelerations between the FI and the WI seem to be associated with their different current structures; a hollow electron current structure for the FI and a center filled current structure for that of the WI. Different electron distributions seem to bring in different current filament structures, eventually leading to different magnetic characteristics.

  16. 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.

  17. 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.

  18. Finite-Time Shock Acceleration of Energetic Storm Particles

    NASA Astrophysics Data System (ADS)

    Channok, Chanruangrit; Ruffolo, David; Desai, Mihir I.; Mason, Glenn M.

    2005-11-01

    Energetic storm particles (ESPs) of various ion species have been shown to arise from suprathermal seed ions accelerated by traveling interplanetary (IP) shocks. The observed spectral rollovers at ~0.1-10 MeV nucleon-1 can be attributed to the finite time available for shock acceleration. Using the locally measured shock strength parameters as inputs, the finite-time shock acceleration model can successfully fit the energy spectra of carbon, oxygen, and iron ions measured by the Ultra Low Energy Isotope Spectrometer (ULEIS) on board the Advanced Composition Explorer (ACE) during three ESP events. The inferred scattering mean free path in the acceleration region ranges from a typical IP value for the weakest ESP event down to 3.0×10-3 AU for the strongest event. This is consistent with the idea that proton-amplified waves result from the very intense particle fluxes in major events.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Fe-rich solar energetic particle events during solar minimum

    NASA Astrophysics Data System (ADS)

    Mazur, J. E.; Mason, G. M.; von Rosenvinge, T. T.

    During the first 10 months of WIND observations, we have detected several time periods with energetic particle abundances that are characteristic of impulsive flares: enrichments in the ³He isotope, and in heavy ions compared to the corona. Using the Supra-Thermal through Energetic Particle sensor on WIND, we find that at ∼100 keV/nucleon these events typically arrive in sequences of multiple events when the spacecraft is magnetically connected to an active region at western solar longitudes, preceding the arrival of a high speed solar wind stream. During recurrent high speed solar wind streams with their associated flux enhancements Fe-rich events are seldom seen: almost all of the events occur on days with solar wind speeds <450 km/sec. The impulsive events we observe arrive at a rate of ∼30 events/year at solar minimum for energies ≥120 keV/nucleon. This rate is comparable to upper limits placed on the observed rate of higher energy ³He-rich events in the last solar minimum with measurements from ISEE-3.

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

    NASA Astrophysics Data System (ADS)

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

    1992-03-01

    The linear response of energetic particles of 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 Δ b is much larger than the mode thickness Δ m, we obtain a new compact expression for the linear power transfer. When Δm/ Δb≪1, the banana orbit effect reduces the power transfer by a factor Δm/ Δb 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 balanced-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 (| v‖|= vA) is substantially enhanced in the beam case compared to the isotropic case, while the contribution at the higher sidebands (| v‖|= vA/(2 l-1) with l⩾2) is substantially reduced.

  7. Finite orbit energetic particle linear response to toroidal Alfven Eigenmodes

    NASA Astrophysics Data System (ADS)

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

    1991-07-01

    The linear response of energetic particles to the toroidal Alfven eigenmodes (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 delta(sub b) is much larger than the mode thickness delta(sub m), we obtain a new compact expression for the linear power transfer. When delta(sub m)/delta(sub b) is much less than 1, the banana orbit effect reduces the power transfer by a factor of delta(sub m)/delta(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 (absolute value of upsilon(parallel) = upsilon(sub A) is substantially enhanced in the beam case compared to the isotropic case, while the contribution at the higher sidebands (absolute value of upsilon(parallel) = upsilon(sub A)/(2l - 1) with l greater than or = 2) is substantially reduced.

  8. A New Phenomenon in Impulsive-Flare-Associated Energetic Particles

    NASA Astrophysics Data System (ADS)

    Chollet, E. E.; Giacalone, J.; Mazur, J. E.; Al Dayeh, M.

    2007-11-01

    We present ACE/ULEIS and Wind/STEP observations of a new and unusual feature of energetic ions between 0.02 and 3 MeV nucleon-1 associated with impulsive solar flares. In addition to the usual velocity dispersion associated with the transit in the heliospheric magnetic field of energetic particles from a small localized source on the Sun, these events also show intermittent behavior that may be related to the magnetic flux tube structure of the solar wind. These are anomalous bursts of low-energy particles, which we call ``tassels.'' Tassels are enhancements of ions extending to much lower energies than those associated with the main event. In one year of data from 2000 June to 2001 July, we have identified two events with tassels, both of which occur simultaneously with interplanetary coronal mass ejections (ICMEs). The tassels may be a superposition of two events, either gradual and impulsive or two impulsive events. Since the tassels could be interpreted as ions arriving earlier than those with the same energy in the main velocity dispersion, we suggest that the tassels occur when the spacecraft intercepts a flux tube with a relatively shorter path length. The decrease in path length may be caused by a decrease in scattering or a shorter travel distance, since flux tubes may be distorted by the passage of the ICME. These tassel events may allow us to infer some of the structure of the ICME.

  9. 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.

  10. Neptune's inner magnetosphere and aurora: Energetic particle constraints

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Krimigis, S. M.; Acuna, M. H.

    1994-01-01

    A dramatic and peculiar dropout of greater than 500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 R(sub N) as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spehrical harmonic model 'O8'). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with maximum L excursions of the ring 1989N1R. The constraints also favor the se of the M2 magnetic field model (Selesnick, 1992) over the previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora.

  11. Energetic Particle Synthesis of Metastable Layers for Superior Mechanical Properties

    SciTech Connect

    Follstaedt, D.M.; Knapp, J.A.; Myers, S.M.; Dugger, M.T.; Friedmann, T.A.; Sullivan, J.P.; Monteiro, O.R.; Ager, J.W. III; Brown, I.G.; Christenson, T.

    1998-01-01

    Energetic particle methods have been used to synthesize two metastable layers with superior mechanical properties: amorphous Ni implanted with overlapping Ti and C, and amorphous diamond-like carbon (DLC) formed by vacuum-arc deposition or pulsed laser deposition. Elastic modulus, yield stress and hardness were reliably determined for both materials by fitting finite-element simulations to the observed layer/substrate responses during nanoindentation. Both materials show exceptional properties, i.e., the yield stress of amorphous Ni(Ti,C) exceeds that of hardened steels and other metallic glasses, and the hardness of DLC (up to 88 GPa) approaches that of crystalline diamond (approx. 100 GPa). Tribological performance of the layers during unlubricated sliding contact appears favorable for treating Ni-based micro-electromechanical systems: stick-slip adhesion to Ni is eliminated, giving a low coefficient of friction (approx. 0.3-0.2) and greatly reduced wear. We discuss how energetic particle synthesis is critical to forming these phases and manipulating their properties for optimum performance.

  12. Neptune's inner magnetosphere and aurora: Energetic particle constraints

    NASA Technical Reports Server (NTRS)

    Mauk, B. H.; Krimigis, S. M.; Acuna, M. H.

    1994-01-01

    A dramatic and peculiar dropout of greater than 500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 R(sub N) as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spehrical harmonic model 'O8'). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with maximum L excursions of the ring 1989N1R. The constraints also favor the se of the M2 magnetic field model (Selesnick, 1992) over the previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora.

  13. Neptune's inner magnetosphere and aurora: Energetic particle constraints

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.; Krimigis, S. M.; Acuna, M. H.

    1994-08-01

    A dramatic and peculiar dropout of greater than 500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 RN as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spehrical harmonic model 'O8'). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with maximum L excursions of the ring 1989N1R. The constraints also favor the se of the M2 magnetic field model (Selesnick, 1992) over the previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora.

  14. 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.

  15. Reduced Quasilinear Models for Energetic Particles Interaction with Alfvenic Eigenmodes

    SciTech Connect

    Ghantous, Katy

    2013-11-01

    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. \\par 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

  16. 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

  17. Solar energetic particles: is there time to hide?

    PubMed

    Reames, D

    1999-06-01

    In the large solar energetic particle (SEP) events that constitute a serious radiation hazard, particles are accelerated at shock waves driven out from the Sun by coronal mass ejections (CMEs). A self-regulating mechanism of wave formation by the streaming particles limits SEP intensities early in the event. Hazardous intensities do not occur until the arrival of the shock itself. This provides an opportunity to warn astronauts to take shelter after the onset of the event at the Sun and before arrival of the shock, a time of approximately 12 h or more. The actual time history of particle intensities depends strongly on the longitude of the event at the Sun, on the width the CME, and especially on the speed of the shock. Fortunately, hazardous events are relatively rare. Unfortunately, this gives us few events to study, so we are forced to extrapolate knowledge gained at lower energies in the frequent smaller events. It is essential that the spacecraft with our best instrumentation be positioned outside the Earth's magnetosphere where they can observe these rare large events when they do occur.

  18. Drift-induced Deceleration of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Dalla, S.; Marsh, M. S.; Laitinen, T.

    2015-07-01

    We investigate the deceleration of solar energetic particles (SEPs) during their propagation from the Sun through interplanetary space, in the presence of weak to strong scattering in a Parker spiral configuration, using relativistic full orbit test particle simulations. The calculations retain all three spatial variables describing particles’ trajectories, allowing us to model any transport across the magnetic field. Large energy change is shown to occur for protons, due to the combined effect of standard adiabatic deceleration and a significant contribution from particle drift in the direction opposite to that of the solar wind electric field. The latter drift-induced deceleration is found to have a stronger effect for SEP energies than for galactic cosmic rays. The kinetic energy of protons injected at 1 MeV is found to be reduced by between 35% and 90% after four days, and for protons injected at 100 MeV by between 20% and 55%. The overall degree of deceleration is a weak function of the scattering mean free path, showing that, although adiabatic deceleration plays a role, a large contribution is due to particle drift. Current SEP transport models are found to account for drift-induced deceleration in an approximate way and their accuracy will need to be assessed in future work.

  19. 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.

  20. DRIFT-INDUCED DECELERATION OF SOLAR ENERGETIC PARTICLES

    SciTech Connect

    Dalla, S.; Marsh, M. S.; Laitinen, T.

    2015-07-20

    We investigate the deceleration of solar energetic particles (SEPs) during their propagation from the Sun through interplanetary space, in the presence of weak to strong scattering in a Parker spiral configuration, using relativistic full orbit test particle simulations. The calculations retain all three spatial variables describing particles’ trajectories, allowing us to model any transport across the magnetic field. Large energy change is shown to occur for protons, due to the combined effect of standard adiabatic deceleration and a significant contribution from particle drift in the direction opposite to that of the solar wind electric field. The latter drift-induced deceleration is found to have a stronger effect for SEP energies than for galactic cosmic rays. The kinetic energy of protons injected at 1 MeV is found to be reduced by between 35% and 90% after four days, and for protons injected at 100 MeV by between 20% and 55%. The overall degree of deceleration is a weak function of the scattering mean free path, showing that, although adiabatic deceleration plays a role, a large contribution is due to particle drift. Current SEP transport models are found to account for drift-induced deceleration in an approximate way and their accuracy will need to be assessed in future work.

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

    SciTech Connect

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

    2016-03-25

    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{sup −α}) of {sup 4}He (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.

  2. Large Energetic Particle Pressures in Solar Cycles 23 and 24

    NASA Astrophysics Data System (ADS)

    Lario, D.; Decker, R. B.; Roelof, E. C.; Viñas, A. F.; Wimmer-Schweingruber, R. F.; Berger, L.

    2017-09-01

    We study periods of elevated energetic particle intensities observed at the L1 Sun-Earth Lagrangian point when the partial energy density associated with energetic (≥80 keV) particles (PEP) dominates that of the local magnetic field (PB) and thermal plasma populations (PPLS). These periods are not uncommon and are frequently observed prior to the passage of interplanetary (IP) shocks. Because of the significant decreases in key solar wind parameters observed during solar cycle 24 [e.g., 1], we were motivated to perform a comparative statistical analysis to determine if the occurrence rate of periods when PEP exceeded PB or PPLS, or both, differed between solar cycles 23 and 24. We find that the general decrease of PB and PPLS in solar cycle 24 was also accompanied by a general decrease of periods with elevated PEP. The result is that solar cycle 24 showed a lower number of time intervals dominated by PEP. We analyze whether these differences can be related to the properties of the IP shocks observed at L1. Incomplete datasets of shock parameters do not show significant differences between solar cycles 23 and 24 that would allow us to explain the difference in the number of periods with PEP>PB and PEP>PPLS. We analyze then the averaged plasma parameters measured in the upstream region of the shocks and find significantly lower solar wind proton temperatures and magnetic field magnitude upstream of IP shocks in solar cycle 24 compared with those in solar cycle 23. These factors, together with the lower level of solar activity, may explain the lower particle intensities in solar cycle 24 and hence the fewer events with PEP>PB and PEP>PPLS.

  3. 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.

  4. 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.

  5. 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.

  6. Energetic Charged Particles in Saturn's Magnetosphere: Voyager 1 Results.

    PubMed

    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

    1981-04-10

    Voyager 1 provided the first look at Saturn's magnetotail and magnetosphere during relatively quiet interplanetary conditions. This report discusses the energetic particle populations of the outer magnetosphere of Saturn and absorption features associated with Titan and Rhea, and compares these observations with Pioneer 11 data of a year earlier. The trapped proton fluxes had soft spectra, represented by power laws E(-gamma) in kinetic energy E, with gamma approximately 7 in the outer magnetosphere and gamma approximately 9 in the magnetotail. Structure associated with the magnetotial was observed as close as 10 Saturn radii (R(s)) on the outbound trajectory. The proton and electron fluxes in the outer magnetosphere and in the magnetotail were variable and appeared to respond to changes in interplanetary conditions. Protons with energies >/= 2 million electron volts had free access to the magnetosphere from interplanetary space and were not stably trapped outside approximately 7.5 R(s).

  7. Solar energetic particle fluences from SOHO/ERNE

    NASA Astrophysics Data System (ADS)

    Valtonen, Eino; Riihonen, Esa; Lehtinen, Iiro-Ville

    2009-03-01

    We have calculated integral fluences of solar protons and helium nuclei at 19 energy thresholds between 1.6 and 90 MeV/n from the SOHO/ERNE measurements during the years 1996-2005. We have also calculated fluences of oxygen and iron in the energy range from 10 up to a few hundred MeV/n for nineteen solar energetic particle (SEP) events. These are the first results of the work aiming at a full employment of the ERNE data in investigating the fluence distributions of SEP events over the entire solar activity cycle 23 and in deriving the total dose received on-board SOHO during its mission. Some instrumental problems are identified and future developments are presented.

  8. PAMELA's Measurements of Anisotropy in Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    The PAMELA satellite experiment, in low Earth orbit since June 2006, is providing comprehensive observations of the Solar Energetic Particle (SEP) fluxes between solar cycles 23 and 24. PAMELA is able to measure SEP spectra over a large interval (>80 MeV) and also measures the flux angular distribution and thus investigates possible anisotropies. The analysis is supported by back-tracing techniques based on a realistic modeling of the terrestrial magnetosphere, which enables to reconstruct the asymptotic pitch-angle distribution of SEPs with respect to the local interplanetary magnetic field. Here we present preliminary results of the anisotropy of several events, which is of relevant interest for the study of GLEs, sub-GLE events, and for the cross-calibration of SEP data provided by different space missions in the present solar cycle.

  9. 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.

  10. Energetic charged particles in Saturn's magnetosphere - Voyager 1 results

    NASA Astrophysics Data System (ADS)

    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.

    1981-04-01

    Voyager 1 provided the first look at Saturn's magnetotail and magnetosphere during relatively quiet interplanetary conditions. This report discusses the energetic particle populations of the outer magnetosphere of Saturn and absorption features associated with Titan and Rhea, and compares these observations with Pioneer 11 data of a year earlier. The trapped proton fluxes had soft spectra, represented by power laws in kinetic energy with an exponent of 7 in the outer magnetosphere and 9 in the magnetotail. Structure associated with the magnetotail was observed as close as 10 Saturn radii on the outbound trajectory. The proton and electron fluxes in the outer magnetosphere and in the magnetotail were variable and appeared to respond to changes in interplanetary conditions. Protons with energies greater than or approximately equal to 2 MeV had free access to the magnetosphere from interplanetary space and were not stably trapped outside about 7.5 Saturn radii.

  11. 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.

  12. 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.

  13. 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.

  14. Spatial Distribution of Solar Energetic Particles in the Inner Heliosphere

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    We study the spatial distribution of solar energetic particles (SEPs) throughout the inner heliosphere during six large SEP events from the period 1977 through 1979, as deduced from observations on the Helios 1 and 2, IMP 7 and 8, ISEE 3, and Voyager 1 and 2 spacecraft. Evidence of intensity maxima associated with the expanding shock wave is commonly seen along its central and western flanks, although the region of peak acceleration or "nose" of the shock is sometimes highly localized in longitude. In one event (1 January 1978) a sharp peak in 20 - 30 MeV proton intensities is seen more strongly by Voyager at ˜ 2 AU than it is by spacecraft at nearby longitudes at ˜ 1 AU. Large spatial regions, or "reservoirs," often exist behind the shocks with spatially uniform SEP intensities and invariant spectra that decrease adiabatically with time as their containment volume expands. Reservoirs are seen to sweep past 0.3 AU and can extend out many AU. Boundaries of the reservoirs can vary with time and with particle velocity, rather than rigidity. In one case, a second shock wave from the Sun reaccelerates protons that retain the same hard spectrum as protons in the reservoir from the preceding SEP event. Thus reservoirs can provide not only seed particles but also a "seed spectrum" with a spectral shape that is unchanged by a weaker second shock.

  15. 3D effects on energetic particle confinement and stability

    NASA Astrophysics Data System (ADS)

    Spong, Don

    2010-11-01

    Understanding the confinement and stability of energetic particle (EP) populations in 3D magnetic configurations is crucial to the future of all toroidal devices. Tokamaks will have weak symmetry-breaking effects from discrete coils, heterogeneous distributions of ferritic materials and non-symmetric (ELM/RWM) control coils, while stellarators and helical RFP states have dominant 3D features by design. Significant EP issues for 3D systems include: modifications of the plasma equilibrium and potential amplification of field errors, asymmetry enhanced EP losses and their impact both on wall heat loads and the confined EP distribution, 3D modifications to the Alfvén gap and mode structure, and the stability properties of EP-destabilized Alfvén modes. 3D equilibria that resolve localized TBM (test blanket module) asymmetries have now been developed for DIII-D and ITER. Such symmetry breaking leads to enhanced EP losses and focused wall deposition. 3D effects also modify the Alfvén spectrum by increasing the number of possibilities for mode coupling and introducing new gap structures, including the helical and mirror gaps, fine scale ripple-induced gaps and continuum crossing gaps. Improved methods have recently been developed for evaluating these modes and their stability, taking into account the large number of coupled modes and finite orbit width effects. Successful Alfvén mode identifications have been made for a range of stellarators, including W7-AS, LHD, HSX and TJ-II. A comprehensive understanding of energetic particle physics with 3D effects is a necessary prerequisite for wall protection, plasma control and flexibility and for new diagnostic development possibilities in future ignited systems.

  16. Analysis of fishbone instability excited by trapped energetic electrons on HL-2A tokamak

    NASA Astrophysics Data System (ADS)

    He, Hongda; Dong, J. Q.; Zhao, K.; He, Zhixiong; Chen, W.; Jiang, H. B.

    2014-11-01

    A generalized dispersion relation for fishbone instability is obtained by considering Gaussian distributions of spatial density and pitch angle of energetic electrons (EEs). The fishbone modes excited by trapped EEs are analysed in detail based on the HL-2A tokamak electron cyclotron resonant heating (ECRH) experiment. Numerical results show that the calculated time evolution of the mode real frequency is in reasonable agreement with the observations in ECRH experiment. Density gradient of the EEs plays an important role in excitation of the modes via resonant interaction between the modes and EEs. The modes are excited at the positions of maximum EE density gradient. The frequency of the mode in the case of on-axis heating is higher than that in the case of off-axis heating. The background plasma tends to prohibit excitation of the fishbone instabilities. The numerical results show that there is a cut-off background plasma density (or background plasma-β) for the fishbone instabilities. In addition, the toroidal magnetic field Bt has to be higher than a critical value in order to excite the mode, and the real frequency of the modes decreases with increasing Bt.

  17. Anomalous diffusion of energetic particles: implications for diffusive particle acceleration at a quasi-perpendicular shock

    SciTech Connect

    Verkhoglyadova, Olga P.; Le Roux, Jakobus A.

    2005-08-01

    We study energetic particle transport in turbulent magnetic fields. The composite turbulence is modeled by a nonlinear structure (vortex) and a randomly fluctuating background magnetic field. Results of our numerical simulations show that an anomalous diffusion regime (subdiffusion and superdiffusion) occurs when the correlation length of the magnetic field disturbances is about the same or larger than the average particle gyroradius. Subdiffusion of cosmic rays in the vicinity of a quasi-perpendicular shock can lower the density of particles at the shock front. Particles become temporarily trapped in the turbulent magnetic fields. The particle spectrum in this case can steepen as compared to the spectrum in the classic diffusive acceleration case. We estimate a power law index for the particle spectrum for a number of cases and discuss implications for cosmic ray transport in the heliosphere.

  18. 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.

  19. 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.

  20. 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.

  1. Solar Energetic Particle Transport Near a Heliospheric Current Sheet

    NASA Astrophysics Data System (ADS)

    Battarbee, Markus; Dalla, Silvia; Marsh, Mike S.

    2017-02-01

    Solar energetic particles (SEPs), a major component of space weather, propagate through the interplanetary medium strongly guided by the interplanetary magnetic field (IMF). In this work, we analyze the implications that a flat Heliospheric Current Sheet (HCS) has on proton propagation from SEP release sites to the Earth. We simulate proton propagation by integrating fully 3D trajectories near an analytically defined flat current sheet, collecting comprehensive statistics into histograms, fluence maps, and virtual observer time profiles within an energy range of 1-800 MeV. We show that protons experience significant current sheet drift to distant longitudes, causing time profiles to exhibit multiple components, which are a potential source of confusing interpretations of observations. We find that variation of the current sheet thickness within a realistic parameter range has little effect on particle propagation. We show that the IMF configuration strongly affects the deceleration of protons. We show that in our model, the presence of a flat equatorial HCS in the inner heliosphere limits the crossing of protons into the opposite hemisphere.

  2. Modeling solar energetic particle events using ENLIL heliosphere simulations

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Mays, M. L.; Odstrcil, D.; Li, Yan; Bain, H.; Lee, C. O.; Galvin, A. B.; Mewaldt, R. A.; Cohen, C. M. S.; Leske, R. A.; Larson, D.; Futaana, Y.

    2017-07-01

    Solar energetic particle (SEP) event modeling has gained renewed attention in part because of the availability of a decade of multipoint measurements from STEREO and L1 spacecraft at 1 AU. These observations are coupled with improving simulations of the geometry and strength of heliospheric shocks obtained by using coronagraph images to send erupted material into realistic solar wind backgrounds. The STEREO and ACE measurements in particular have highlighted the sometimes surprisingly widespread nature of SEP events. It is thus an opportune time for testing SEP models, which typically focus on protons 1-100 MeV, toward both physical insight to these observations and potentially useful space radiation environment forecasting tools. Some approaches emphasize the concept of particle acceleration and propagation from close to the Sun, while others emphasize the local field line connection to a traveling, evolving shock source. Among the latter is the previously introduced SEPMOD treatment, based on the widely accessible and well-exercised WSA-ENLIL-cone model. SEPMOD produces SEP proton time profiles at any location within the ENLIL domain. Here we demonstrate a SEPMOD version that accommodates multiple, concurrent shock sources occurring over periods of several weeks. The results illustrate the importance of considering longer-duration time periods and multiple CME contributions in analyzing, modeling, and forecasting SEP events.

  3. 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.

  4. 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.

  5. Time Evolution of Elemental Ratios in Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Zelina, P.; Dalla, S.; Cohen, C. M. S.; Mewaldt, R. A.

    2017-01-01

    Heavy ion ratio abundances in solar energetic particle (SEP) events, e.g., Fe/O, often exhibit decreases over time. Using particle instruments on the Advanced Composition Explorer, Solar and Heliospheric Observatory and Solar Terrestrial Relations Observatory spacecraft, we analyzed heavy ion data from 4 SEP events taking place between 2006 December and 2014 December. We constructed 36 different ionic pairs and studied their time evolution in each event. We quantified the temporal behavior of abundant SEP ratios by fitting the data to derive a decay time constant B. We also considered the ratio of ionic mass-to-charge for each pair, the S value given, e.g., for Fe/O by {S}{Fe/{{O}}}={(M/Q)}{Fe}/{(M/Q)}{{O}}. We found that the temporal behavior of SEP ratios is ordered by the value of S: ratios with S> 1 showed decreases over time (i.e., B< 0) and those with S< 1 showed increases (B> 0). We plotted B as a function of S and observed a clear monotonic dependence: ratios with a large S decayed at a higher rate. A prominent discontinuity at S = 2.0 (corresponding to He/H) was found in three of the four events, suggesting anomalous behavior of protons. The X/H ratios often show an initial increase followed by a decrease, and decay at a slower rate. We discuss possible causes of the observed B versus S trends within current understanding of SEP propagation.

  6. Non-conventional Fishbone Instabilities

    SciTech Connect

    Ya.I. Kolesnichenko; V.V. Lutsenko; V.S. Marchenko; R.B. White

    2004-11-10

    New instabilities of fishbone type are predicted. First, a trapped-particle-induced m = n = 1 instability with the mode structure having nothing to do with the conventional rigid kink displacement. This instability takes place when the magnetic field is weak, so that the precession frequency of the energetic ions is not small as compared to the frequency of the corresponding Alfven continuum at r = 0 and the magnetic shear is small inside the q = 1 radius [the case relevant to spherical tori]. Second, an Energetic Particle Mode fishbone instability driven by circulating particles. Third, a double-kink-mode instability driven by the circulating energetic ions. In particular, the latter can have two frequencies simultaneously: we refer to it as ''doublet'' fishbones. This instability can occur when the radial profile of the energetic ions has an off-axis maximum inside the region of the mode localization.

  7. Development of An Energetic Particle Module and Integration into IMFIT With Initial Applications

    NASA Astrophysics Data System (ADS)

    Guo, W.; Chu, M. S.; Lao, L. L.; Liu, Y. Q.; Ren, Q.; Li, G.; Pan, C.; Yadykin, D.

    2009-11-01

    The performance of future burning tokamak experiments depends critically on the behavior of energetic particles. To facilitate the validation of energetic particle physics in present-day experiments, an energetic particle physics module is being developed and integrated into the IMFIT Integrated Modeling tool. This IMFIT module provides a convenient platform to facilitate interactions among various physics codes starting from the experimental data to the analysis of stability and transport with the inclusion of energetic particles. Key components of the module include the EFIT, NUBEAM, CONT, ONETWO, and MARS-K codes, in which the effects of fast ions have been implanted. Starting from experimental data, the energetic particle distribution function is obtained by using various birth and transport models, and their subsequent effect on the stability and transport of the background plasma studied. Initial applications using DIII-D experimental data will be presented.

  8. 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.

  9. Jetting instability mechanisms of particles from explosive dispersal

    NASA Astrophysics Data System (ADS)

    Ripley, R. C.; Zhang, F.

    2014-05-01

    The formation of post-detonation 'particle' jets is widely observed in many problems associated with explosive dispersal of granular materials and liquids. Jets have been shown to form very early, however the mechanism controlling the number of jetting instabilities remains unresolved despite a number of active theories. Recent experiments involving cylindrical charges with a range of central explosive masses for dispersal of dry solid particles and pure liquid are used to formulate macroscopic numerical models for jet formation and growth. The number of jets is strongly related to the dominant perturbation during the shock interaction timescale that controls the initial fracturing of the particle bed and liquid bulk. Perturbations may originate at the interfaces between explosive, shock-dispersed media, and outer edge of the charge due to Richtmyer-Meshkov instabilities. The inner boundary controls the number of major structures, while the outer boundary may introduce additional overlapping structures and microjets that are overtaken by the major structures. In practice, each interface may feature a thin casing material that breaks up, thereby influencing or possibly dominating the instabilities. Hydrocode simulation is used to examine the role of each interface in conjunction with casing effects on the perturbation leading to jet initiation. The subsequent formation of coherent jet structures requires dense multiphase flow of particles and droplets that interact though inelastic collision, agglomeration, and turbulent flow. Macroscopic multiphase flow simulation shows dense particle clustering and major jet structures overtaking smaller instabilities. Late-time dispersal is controlled by particle drag and evaporation of droplets. Numerical results for dispersal and jetting evolution are compared with experiments.

  10. 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).

  11. SEPServer's added value to Solar Energetic Particle (SEP) Research

    NASA Astrophysics Data System (ADS)

    Malandraki, Olga; Vainio, Rami; Papaioannou, Athanasios; Agueda, Neus; Klein, Karl-Ludwig; Heber, Bernd; Valtonen, Eino; Nindos, Alexander; Dröge, Wolfgang; Kartavykh, Yulia; Rodriguez-Gasén, Rosa; Vimer, Nicole; Heynderickx, Daniel; Braune, Stephan

    2014-05-01

    SEPServer brings together a wealth of SEP data, analysis methods and diverse but at the same time interconnected solar and heliospheric communities. It thus provides an open tool that advances our understanding of SEP propagation and acceleration. The scientific conclusions of this effort are drawn with the implementation and release to the SEP community of multiple SEP event catalogs based on different spacecrafts and instruments, covering a broad timescale from 1975 to 2013 as well as a variety of distances from 0.3 to ~5 AU within the heliosphere. SEP events from Helios A & B missions, going back to 1975, at distances 0.3-1 AU, together with their Electromagnetic (EM) counterpart from OSRA data (from Leibniz Institut für Astrophysik Potsdam) are being released for the first time. A catalog covering solar cycle 23 based upon the Solar and Heliospheric Observatory (SOHO)/ Energetic and Relativistic Nuclei and Electron (ERNE) high-energy (~68 MeV) protons at 1 AU with parallel analysis of SOHO/ Electron Proton Helium Instrument (EPHIN) and Advanced Composition Explorer (ACE) / Electron, Proton and Alpha Monitor (EPAM) data, including the relevant EM associations has also been delivered. Furthermore, the first complete Solar TErrestrial RElations Observatory (STEREO) SEP catalog based on the Low Energy Telescope (LET) protons (6-10 MeV) and the Solar Electron Proton Telescope (SEPT) electrons (55-85 keV) from 2007 to 2012 has been implemented. Moreover, the Cosmic Ray and Solar Particle Investigation (COSPIN) Kiel Electron Telescope (KET) data of 38-125 MeV has been used to identify a new catalog of SEP events observed in and out of the ecliptic plane over solar cycle 23, with simultaneous analysis of electrons recorded by the Heliosphere Instrument for Spectra, Composition and Anisotropy at Low Energies (HISCALE). For selected cases simulation based analysis has been applied in order to identify the timing of the injection history and to provide a cross reference

  12. Critical Next Steps in Understanding Solar Energetic Particle Events (Invited)

    NASA Astrophysics Data System (ADS)

    Mason, G. M.

    2010-12-01

    Solar energetic particle (SEP) events are the most powerful explosions in the solar system, capable of accelerating charged particles to relativistic energies. In the space age they are being intensely studied not only due to their impact on space systems and advanced technologies, but also because modern observations have revealed that particle acceleration is a nearly universal phenomenon at sites through the solar system and galaxy. At the Sun, where multiple remote and in-situ features of SEPs can be obtained, we have the opportunity to develop an understanding the physics of these events which in other astrophysical site can be observed only remotely. Although large SEP events are clearly associated with flare events and associated Coronal Mass Ejections (CMEs), magnetic fields in the corona and interplanetary space confine and scatter the particles so that by the time they reach Earth orbit, many features have become thoroughly mixed. Basic questions about SEP acceleration thus remain open, such as: what are the roles of flares and CMEs in SEP acceleration? How do SEPs reach the interplanetary medium? What is the actual material (seed population) that is accelerated? During the past solar cycle, progress in understanding SEPs has resulted from greatly improved particle observations combined with remote sensing of flares, CMEs, and coronal and interplanetary shocks. This has led to new insights into both large, shock associated SEP events, and smaller 3He-rich events which may occur in the low corona. In the next few years, progress in SEP studies can be expected from multipoint measurements using STEREO and advanced imaging from SDO. Critical new insights will then emerge from the ESA Solar Orbiter and NASA Solar Probe Plus missions that will travel to the inner heliosphere where the signatures of SEPs will be nearly free of the interplanetary mixing, allowing accurate and decisive comparisons of observations with remote observations and theoretical models

  13. Observations of Energetic Particle Escape at the Magnetopause: Early Results from the MMS Energetic Ion Spectrometer (EIS)

    NASA Technical Reports Server (NTRS)

    Cohen, I. J.; Mauk, B. H.; Anderson, B. J.; Westlake, J. H.; Sibeck, David Gary; Giles, Barbara L.; Pollock, C. J.; Turner, D. L.; Fennell, J. F.; Blake, J. B.; hide

    2016-01-01

    Energetic (greater than tens of keV) magnetospheric particle escape into the magnetosheath occurs commonly, irrespective of conditions that engender reconnection and boundary-normal magnetic fields. A signature observed by the Magnetospheric Multiscale (MMS) mission, simultaneous monohemispheric streaming of multiple species (electrons, H+, Hen+), is reported here as unexpectedly common in the dayside, dusk quadrant of the magnetosheath even though that region is thought to be drift-shadowed from energetic electrons. This signature is sometimes part of a pitch angle distribution evolving from symmetric in the magnetosphere, to asymmetric approaching the magnetopause, to monohemispheric streaming in the magnetosheath. While monohemispheric streaming in the magnetosheath may be possible without a boundary-normal magnetic field, the additional pitch angle depletion, particularly of electrons, on the magnetospheric side requires one. Observations of this signature in the dayside dusk sector imply that the static picture of magnetospheric drift-shadowing is inappropriate for energetic particle dynamics in the outer magnetosphere.

  14. Observations of energetic particle escape at the magnetopause: Early results from the MMS Energetic Ion Spectrometer (EIS)

    NASA Astrophysics Data System (ADS)

    Cohen, I. J.; Mauk, B. H.; Anderson, B. J.; Westlake, J. H.; Sibeck, D. G.; Giles, B. L.; Pollock, C. J.; Turner, D. L.; Fennell, J. F.; Blake, J. B.; Clemmons, J. H.; Jaynes, A. N.; Baker, D. N.; Craft, J. V.; Spence, H. E.; Niehof, J. T.; Reeves, G. D.; Torbert, R. B.; Russell, C. T.; Strangeway, R. J.; Magnes, W.; Trattner, K. J.; Fuselier, S. A.; Burch, J. L.

    2016-06-01

    Energetic (greater than tens of keV) magnetospheric particle escape into the magnetosheath occurs commonly, irrespective of conditions that engender reconnection and boundary-normal magnetic fields. A signature observed by the Magnetospheric Multiscale (MMS) mission, simultaneous monohemispheric streaming of multiple species (electrons, H+, Hen+), is reported here as unexpectedly common in the dayside, dusk quadrant of the magnetosheath even though that region is thought to be drift-shadowed from energetic electrons. This signature is sometimes part of a pitch angle distribution evolving from symmetric in the magnetosphere, to asymmetric approaching the magnetopause, to monohemispheric streaming in the magnetosheath. While monohemispheric streaming in the magnetosheath may be possible without a boundary-normal magnetic field, the additional pitch angle depletion, particularly of electrons, on the magnetospheric side requires one. Observations of this signature in the dayside dusk sector imply that the static picture of magnetospheric drift-shadowing is inappropriate for energetic particle dynamics in the outer magnetosphere.

  15. The Delay of Low-energy Particle Populations in Association with Large Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Al-Dayeh, M.; Desai, M. I.; Dwyer, J. R.; Rassoul, H. K.; Mason, G.; Mazur, J.

    2008-05-01

    Using ~0.045-10 MeV/nucleon ion data from ACE/ULEIS, we have found that a substantial number of shock- associated solar energetic particle events (~20 events) have significant delays in the arrival of the low- energy component beyond what is expected from the travel time of energetic particles from the sun to the earth at 1 AU. Indeed, for some events, after correcting for the velocity dispersion, the low energy component (~sub- MeV/nucleon) is almost completely absent while the high-energy component (E > 1 MeV/nucleon) has very large enhancements. SEP events with the most dramatic initial depletion of low-energy particles are accompanied by large proton fluxes and have large enhancements of the low-energy particles later, in coincidence with the arrival of the interplanetary shock, a day or two after the start of the event. In addition, these events show Fe/O enhancements during the periods in which the low-energy component is depleted and lower Fe/O values once the shock arrives. These new observations appear to be explained by the trapping of particles with low energy-to-charge (E/Q) ratios in the vicinity of the shock by magnetohydrodynamic waves, possibly generated by high energy protons streaming along the magnetic field lines.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Ogawa, K.; Isobe, M.; Toi, K.; Watanabe, F.; Spong, D. A.; Shimizu, A.; Osakabe, M.; Ohdachi, S.; Sakakibara, S.; LHD Experiment Group

    2010-08-01

    Energetic-ion losses induced by toroidicity-induced Alfvén 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 = 190 keV down to 130 keV, while RICs expel energetic ions of E = 190 keV down 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.

  18. 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

  19. 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.

  20. 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.

  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. 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.

  3. 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.

  4. 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.

  5. Calibration of the Solar Orbiter Energetic Particle Detector Suite

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, R. F.; Rodriguez-Pacheco, J.; Martin-Garcia, C.; Kulkarni, S. R.; Panitzsch, L.; Boettcher, S.; Mason, G. M.; Kohler, J.; Ho, G. C.; Boden, S.; Grunau, J.; Steinhagen, J.; Terasa, C.; Yu, J.; Prieto, M.; Gomez-Herrero, R.; Blanco, J.

    2013-12-01

    We present the current status and plans for the calibration of the Energetic Particle Detector (EPD) suite on ESA's Solar Orbiter mission. Solar Orbiter is scheduled to launch in January 2017, instrument delivery in January 2015. EPD consists of four sensors: the SupraThermal Electron and Proton (STEP) sensor covers electrons (protons) from 2 (3) keV up to 100 keV, the Electron Proton Telescope (EPT) from 20 to 300 (7000) keV, the Suprathermal Ion Spectrograph (SIS) determines the ionic composition from ~0.05 to ~10 MeV/nuc (species dependent), and the High Energy Telescope (HET) measures electrons and protons (ions) from 0.3 to 30 and 10 to >100 MeV/nuc (20 - 200 MeV/nuc species dependent). EPT, HET, and SIS have two approximately opposite-facing fields of view, EPT, and HET share a common electronics box, two EPT/HET sensors allow the determination of second-order anisotropies (a total of 4 FoVs). Apart from the use of radioactive sources, STEP will be calibrated at the Kiel calibration facilities, EPT both at Kiel (electrons and low-energy protons) as well as at PTB in Braunschweig. SIS will undergo calibration at the LBL 88' cyclotron, HET at HIMAC in Chiba, Japan. Tests of the electron/protons discrimination of EPT show the expected behavior, HET prototypes have already been calibrated and the results will be shown.

  6. ISEE-3 measurements of solar energetic particle composition

    NASA Astrophysics Data System (ADS)

    von Rosenvinge, T. T.; Reames, D. V.

    1980-10-01

    Preliminary observations of energetic particles from solar flares beginning on September 23 and November 10, 1978 are reported. The measurements were made from the ISEE-3 spacecraft using very thin, large area solid-state detectors. Charge composition was measured for all elements from Z = 2 to Z = 26 above approximately 2 MeV/nucleon. More than 100,000 nuclei with Z greater than 2 were pulse-height analyzed during the course of the first event, while the second was substantially smaller. These good statistics enable the observation of variations in composition at low energies as a function of time. For example, the Fe/O ratio (2.0-3.1 MeV/n) was observed in the September event to decrease by a factor of approximately 5. By contrast, this same ratio increased by a factor of approximately 1.5 during the November 10 event. Similar variations have been reported earlier by Scholer et al. (1978). These authors, however were unable to observe the He/O ratio which has now been observed also to show significant variation.

  7. 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.

  8. {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.

  9. 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.

  10. SOLAR ENERGETIC PARTICLE MODULATIONS ASSOCIATED WITH COHERENT MAGNETIC STRUCTURES

    SciTech Connect

    Trenchi, L.; Bruno, R.; D'amicis, R.; Marcucci, M. F.; Telloni, D.; Zurbuchen, T. H.; Weberg, M.

    2013-06-10

    In situ observations of solar energetic particles (SEPs) often show rapid variations of their intensity profile, affecting all energies simultaneously, without time dispersion. A previously proposed interpretation suggests that these modulations are directly related to the presence of magnetic structures with a different magnetic topology. However, no compelling evidence of local changes in magnetic field or in plasma parameters during SEP modulations has been reported. In this paper, we performed a detailed analysis of SEP events and we found several signatures in the local magnetic field and/or plasma parameters associated with SEP modulations. The study of magnetic helicity allowed us to identify magnetic boundaries, associated with variations of plasma parameters, which are thought to represent the borders between adjacent magnetic flux tubes. It is found that SEP dispersionless modulations are generally associated with such magnetic boundaries. Consequently, we support the idea that SEP modulations are observed when the spacecraft passes through magnetic flux tubes, filled or devoid of SEPs, which are alternatively connected and not connected with the flare site. In other cases, we found SEP dropouts associated with large-scale magnetic holes. A possible generation mechanism suggests that these holes are formed in the high solar corona as a consequence of magnetic reconnection. This reconnection process modifies the magnetic field topology, and therefore, these holes can be magnetically isolated from the surrounding plasma and could also explain their association with SEP dropouts.

  11. Foretelling Flares and Solar Energetic Particle Events: the FORSPEF tool

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Anastasios; Papaioannou, Athanasios; Sandberg, Ingmar; Georgoulis, Manolis K.; Tziotziou, Kostas; Jiggens, Piers

    2017-04-01

    A novel integrated prediction system, for both solar flares (SFs) and solar energetic particle (SEP) events is being presented. The Forecasting Solar Particle Events and Flares (FORSPEF) provides forecasting of solar eruptive events, such as SFs with a projection to coronal mass ejections (CMEs) (occurrence and velocity) and the likelihood of occurrence of a SEP event. In addition, FORSPEF, also provides nowcasting of SEP events based on actual SF and CME near real-time data, as well as the complete SEP profile (peak flux, fluence, rise time, duration) per parent solar event. The prediction of SFs relies on a morphological method: the effective connected magnetic field strength (Beff); it is based on an assessment of potentially flaring active-region (AR) magnetic configurations and it utilizes sophisticated analysis of a large number of AR magnetograms. For the prediction of SEP events new methods have been developed for both the likelihood of SEP occurrence and the expected SEP characteristics. In particular, using the location of the flare (longitude) and the flare size (maximum soft X-ray intensity), a reductive statistical method has been implemented. Moreover, employing CME parameters (velocity and width), proper functions per width (i.e. halo, partial halo, non-halo) and integral energy (E>30, 60, 100 MeV) have been identified. In our technique warnings are issued for all > C1.0 soft X-ray flares. The prediction time in the forecasting scheme extends to 24 hours with a refresh rate of 3 hours while the respective prediction time for the nowcasting scheme depends on the availability of the near real-time data and falls between 15-20 minutes for solar flares and 6 hours for CMEs. We present the modules of the FORSPEF system, their interconnection and the operational set up. The dual approach in the development of FORPSEF (i.e. forecasting and nowcasting scheme) permits the refinement of predictions upon the availability of new data that characterize changes on

  12. The Detection of Coronal Suprathermal Particles Required to Seed Acceleration of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Moses, J.; Laming, J. M.; Tylka, A.; Ko, Y.; Rakowski, C.; Ng, C. K.

    2012-12-01

    An extensive body of evidence identifies shocks driven by very fast coronal mass ejections (CMEs) starting within a few solar radii of the Sun as the primary particle accelerators in large, gradual solar energetic particles (SEP) events. These large SEP events are major radiation hazards for astronauts and for space borne instrumentation, making a reliable SEP predictive capability a high priority for Heliophysics research. Diverse lines of evidence indicate that the rapid production of large intensities of high-energy particles is greatly enhanced when the pre-event environment has been primed with a population of suprathermal ions having energies well above the typical thermal particle energy, usually in the range from a few to tens of keV in the solar corona. However, at present we have no direct evidence that suprathermal ions actually exist in the corona in numbers sufficient to serve as "seed particles" for diffusive shock acceleration (DSA). We will review the evidence indicating seed particles are required to produce energetic SEPs on the observed time scales. One technique with the potential for directly observing these seed particles is the use of high-throughput UV spectroscopy to quantify broadening of the Ly-α line resulting from charge exchange between suprathermal protons and neutral atoms in the corona. Attempts to use this technique with SOHO UVCS have not produced clear evidence for the detection of coronal suprathermals. We will present revised spectroscopic computations of the influence of seed particles on the Ly-α line spectrum and describe the instrumental requirements for observing this line broadening.

  13. 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.

  14. JEDI -- The Jupiter Energetic Particle Detector for the Juno mission

    NASA Astrophysics Data System (ADS)

    Haggerty, D. K.; Mauk, B. H.; Paranicas, C. P.

    2008-12-01

    The Juno mission provides the first opportunity to conduct an in-depth exploration of Jupiter's polar magnetosphere. The high-inclination, low-periapsis orbit provides in-situ access to three critical regions: the auroral magnetic field lines, the equatorial magnetosphere, and the polar ionosphere. The Jupiter Energetic Particle Detector Instrument (JEDI) is one of several Juno magnetospheric instruments that will work together to resolve critical scientific questions about these novel environments, most importantly how Jupiter's dramatic aurora is generated. JEDI measures the energy, spectra, mass species (H, He, O, S), and angular distributions of the higher energy charged particles that: 1) are accelerated at low altitude by Jovian auroral processes, 2) precipitate into Jupiter's upper atmosphere, 3) heat and ionize the Jovian upper atmosphere, and 4) populate Jupiter's inner magnetosphere. JEDI is a compact, light-weight, time-of-flight (TOF) spectrometer that makes 3-parameter TOF and energy ion measurements, 2-parameter TOF-only ion measurements, and single parameter electron measurements in the 10-keV to 10-MeV ion and the 25-keV to 1-MeV electron energy range. The rapid spacecraft motion and slow spacecraft rotation requires that JEDI simultaneously and continuously resolve both magnetic loss cones at every position inside of ~3RJ. To achieve these measurements JEDI uses multiple sensors, each with six angular sectors evenly distributed in a 160° x 12° fan. Through these multiple views JEDI continuously samples within a 360° plane roughly normal to the spacecraft spin axis with full-sky coplanar coverage achieved each spacecraft spin. JEDI with its low resource requirements and rad-hard, high-speed electronics will make the demanding scientific observations required by the Juno mission.

  15. Microwave observations for forecasting energetic particles from the Sun

    NASA Astrophysics Data System (ADS)

    Zucca, Pietro; Nuñez, Marlon; Klein, Karl-Ludwig; Malandraki, Olga; Pavlos, Evgenios; Miteva, Rositsa

    2017-04-01

    Solar energetic particles (SEPs), especially protons and heavy ions, are a major space weather hazard when they impact spacecraft and the terrestrial atmosphere. Forecasting schemes have been developed, which use earlier signatures of particle acceleration to predict the arrival of solar protons and ions in the space environment of the Earth. In this study, we investigate the advantages of microwave observations for forecasting the SEP occurrence and SEP energy spectrum. The UMASEP scheme forecasts the occurrence and the importance of a SEP event based on combined observations of soft X-rays, their time derivative, and protons above 10 MeV at geosynchronous orbit. We explore the possibility to replace the derivative of the soft X-ray time history by the microwave time history in the UMASEP scheme. For the forecast of the SEP energy spectrum, we investigate if the hardness or softness of the proton spectrum in interplanetary space can be predicted from the shape of the microwave spectrum. The technique developed by Chertok et al (2009) is to use the ratio of peak microwave flux densities near 9 and 15 GHz as a predictor. Here, we tested this scheme over solar cycle 23 and 24. A detailed analysis of the results including limitations the methods are presented. We conclude that microwave patrol observations improve SEP forecasting schemes that employ soft X-rays. High-quality microwave data available in real time appear as a significant addition to our ability to predict SEP occurrence and their energy spectrum. Acknowledgements: This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 637324

  16. 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.

  17. Predicting Flares and Solar Energetic Particle Events: The FORSPEF Tool

    NASA Astrophysics Data System (ADS)

    Anastasiadis, A.; Papaioannou, A.; Sandberg, I.; Georgoulis, M.; Tziotziou, K.; Kouloumvakos, A.; Jiggens, P.

    2017-09-01

    A novel integrated prediction system for solar flares (SFs) and solar energetic particle (SEP) events is presented here. The tool called forecasting solar particle events and flares (FORSPEF) provides forecasts of solar eruptive events, such as SFs with a projection to occurrence and velocity of coronal mass ejections (CMEs), and the likelihood of occurrence of an SEP event. In addition, the tool provides nowcasting of SEP events based on actual SF and CME near real-time data, as well as the SEP characteristics ( e.g. peak flux, fluence, rise time, and duration) per parent solar event. The prediction of SFs relies on the effective connected magnetic field strength (B_{eff}) metric, which is based on an assessment of potentially flaring active-region (AR) magnetic configurations, and it uses a sophisticated statistical analysis of a large number of AR magnetograms. For the prediction of SEP events, new statistical methods have been developed for the likelihood of the SEP occurrence and the expected SEP characteristics. The prediction window in the forecasting scheme is 24 hours with a refresh rate of 3 hours, while the respective prediction time for the nowcasting scheme depends on the availability of the near real-time data and ranges between 15 - 20 minutes for solar flares and 6 hours for CMEs. We present the modules of the FORSPEF system, their interconnection, and the operational setup. Finally, we demonstrate the validation of the modules of the FORSPEF tool using categorical scores constructed on archived data, and we also discuss independent case studies.

  18. Early results on energetic particle dynamics and structure from the Energetic Ion Spectrometer (EIS) on the Magnetospheric Multiscale (MMS) mission

    NASA Astrophysics Data System (ADS)

    Cohen, I. J.; Mauk, B.; Westlake, J. H.; Anderson, B. J.; Turner, D. L.; Fennell, J. F.; Spence, H. E.; Baker, D. N.; Pollock, C. J.; Torbert, R. B.; Blake, J. B.; Sibeck, D. G.

    2015-12-01

    The cluster of four, formation-flying spacecraft, comprising the Magnetospheric Multiscale (MMS) mission, launched on 13 March 2015 into near equatorial 1.2 x 12 RE orbits, provides an important new asset for assessing the transport of energy and matter from the distant regions of Earth's magnetosphere into the inner regions. Here we report on early results from the Energetic Ion Spectrometer (EIS) instrument on each of the MMS Spacecraft. EIS provides nearly all-sky energetic ion energy, angle and elemental compositional distributions for < 20 keV for protons and 45 keV for oxygen ions, up to > 1 MeV. It also measures energetic electrons from 25 keV to > 0.5 MeV in support and coordination with the electron-focused Fly's Eye Energetic Particle Spectrometer (FEEPS). During the early phase of the MMS mission, while the full complement of instruments was being commissioned prior to the prime mission phase beginning 1 September 2015, EIS observed dynamic energetic particle injections at the root of the magnetotail between the post-midnight regions and dawn in association with numerous dipolarization fronts and related processes. Here we report on coordinated measurements between MMS's EIS instrument and EIS's sister instrument on the Van Allen Probes, RBSPICE, to further address the relationship between dynamic injections and depolarization fronts in the magnetotail and injections observed deep within the magnetosphere's ring current regions. We also report preliminary result on using energetic particle gradients and anistotropies to diagnose magnetopause structures near mission-identified reconnection sites.

  19. 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

  20. 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.

  1. Multi-Spacecraft Analysis of Energetic Heavy Ions and Interplanetary Shock Properties in Energetic Storm Particle Events at 1 AU

    NASA Astrophysics Data System (ADS)

    Ebert, R. W.; Dayeh, M. A.; Desai, M. I.; Li, G.; Mason, G. M.

    2015-12-01

    Energetic storm particle (ESP) events are believed to occur as a result of diffusive shock acceleration at coronal mass ejection (CME)-driven interplanetary (IP) shocks. In situ observations of ESPs provide an excellent tool to study the physics of shock acceleration and the mechanisms that energize particles in events where the IP shock is remote (e.g. solar energetic particles - SEPs - that are accelerated in the solar corona). In this study, we use 1 AU observations during solar cycle 24 from ACE, STEREO-A, and STEREO-B during several ESP events observed at two or more spacecraft to examine the relationship between IP shocks and their associated energetic particles. Specifically, we examine the connection between variations in the properties of ~0.1 - 5 MeV/nucleon heavy ions (e.g. peak intensities, energy spectra, abundances) and IP shock parameters (e.g. shock obliquity, compression ratio, Mach number) that are observed at different points along the same CME-driven shock front. These results will be compared with theoretical predictions for heavy ion energy spectra and abundances in ESP events and could provide important additional constraints for particle acceleration in the inner heliosphere.

  2. 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

  3. Dione flybys in the view of energetic particles

    NASA Astrophysics Data System (ADS)

    Krupp, Norbert; Roussos, Elias; Kriegel, Henrik; Kollmann, Peter; Kivelson, Margaret G.; Kotova, Anna; Regoli, Leonardo; Paranicas, Christopher P.; Mitchell, Don; Krimigis, Stamatios M.; Khurana, Krishan

    2016-10-01

    We report on the results of energetic electron measurements above 15 keV from the Low Energy Magnetospheric Measurement System LEMMS, part of the Magnetospheric Imaging Instrument MIMI onboard Cassini during the five close Dione flybys combined with measurements of the magnetometer instrument MAG - an update of the paper by Krupp et al. 2013. We found particles in the vicinity of Dione bouncing and drifting 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. For the upstream encounter D1 energy-dependent ion absorption signatures were measured with the evidence that protons present in the upstream region can explain the observed dropout features. The flybys D2 and D3 went through the moon's geometrical wake and we observed energy dependent asymmetric absorption signatures in the fluxes of electrons between the planetward and anti-planetward sectors of the moon's wake at energies above about 100 keV. The most recent flybys D4 and D5 went directly over the north pole of the moon and showed absorption signatures when connected with the moon's flux tube. 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.) 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 in the data.

  4. 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.

  5. Energetic-particle abundances in impulsive solar flare events

    NASA Technical Reports Server (NTRS)

    Reames, D. V.; Meyer, J. P.; Von Rosenvinge, T. T.

    1994-01-01

    We report on the abundances of energetic particles from impulsive solar flares, including those from a survey of 228 He-3 rich events, with He-3/He-4 is greater than 0.1, observed by the International Sun Earth Explorer (ISEE) 3 spacecraft from 1978 August through 1991 April. The rate of occurrence of these events corresponds to approximately 1000 events/yr on the solar disk at solar maximum. Thus the resonant plasma processes that enhance He-3 and heavy elements are a common occurrence in impulsive solar flares. To supply the observed fluence of He-3 in large events, the acceleration must be highly efficient and the source region must be relatively deep in the atmosphere at a density of more than 10(exp 10) atoms/cu cm. He-3/He-4 may decrease in very large impulsive events because of depletion of He-3 in the source region. The event-to-event variations in He-3/He-4, H/He-4, e/p, and Fe/C are uncorrelated in our event sample. Abundances of the elements show a pattern in which, relative to coronal composition, He-4, C, N, and O have normal abundance ratios, while Ne, Mg, and Si are enhanced by a factor approximately 2.5 and Fe by a factor approximately 7. This pattern suggests that elements are accelerated from a region of the corona with an electron temperature of approximately 3-5 MK, where elements in the first group are fully ionized (Q/A = 0.5), those in the second group have two orbital electrons (Q/A approximately 0.43), and Fe has Q/A approximately 0.28. Ions with the same gyrofrequency absorb waves of that frequency and are similarly accelerated and enhanced. Further stripping may occur after acceleration as the ions begin to interact with the streaming electrons that generated the plasma waves.

  6. 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.

  7. 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.

  8. FIRE HOSE INSTABILITY DRIVEN BY ALPHA PARTICLE TEMPERATURE ANISOTROPY

    SciTech Connect

    Matteini, L.; Schwartz, S. J.; Hellinger, P.; Landi, S.

    2015-10-10

    We investigate properties of a solar wind-like plasma, including a secondary alpha particle population exhibiting a parallel temperature anisotropy with respect to the background magnetic field, using linear and quasi-linear predictions and by means of one-dimensional hybrid simulations. We show that anisotropic alpha particles can drive a parallel fire hose instability analogous to that generated by protons, but that, remarkably, can also be triggered when the parallel plasma beta of alpha particles is below unity. The wave activity generated by the alpha anisotropy affects the evolution of the more abundant protons, leading to their anisotropic heating. When both ion species have sufficient parallel anisotropies, both of them can drive the instability, and we observe the generation of two distinct peaks in the spectra of the fluctuations, with longer wavelengths associated to alphas and shorter ones to protons. If a non-zero relative drift is present, the unstable modes propagate preferentially in the direction of the drift associated with the unstable species. The generated waves scatter particles and reduce their temperature anisotropy to a marginally stable state, and, moreover, they significantly reduce the relative drift between the two ion populations. The coexistence of modes excited by both species leads to saturation of the plasma in distinct regions of the beta/anisotropy parameter space for protons and alpha particles, in good agreement with in situ solar wind observations. Our results confirm that fire hose instabilities are likely at work in the solar wind and limit the anisotropy of different ion species in the plasma.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Pogorelov, N. V.; Fichtner, H.; Czechowski, A.; Lazarian, A.; Lembege, B.; le Roux, J. A.; Potgieter, M. S.; Scherer, K.; Stone, E. C.; Strauss, R. D.; Wiengarten, T.; Wurz, P.; Zank, G. P.; Zhang, M.

    2017-04-01

    This paper summarizes the results obtained by the team "Heliosheath Processes and the Structure of the Heliopause: Modeling Energetic Particles, Cosmic Rays, and Magnetic Fields" supported by the International Space Science Institute (ISSI) in Bern, Switzerland. We focus on the physical processes occurring in the outer heliosphere, especially at its boundary called the heliopause, and in the local interstellar medium. The importance of magnetic field, charge exchange between neutral atoms and ions, and solar cycle on the heliopause topology and observed heliocentric distances to different heliospheric discontinuities are discussed. It is shown that time-dependent, data-driven boundary conditions are necessary to describe the heliospheric asymmetries detected by the Voyager spacecraft. We also discuss the structure of the heliopause, especially due to its instability and magnetic reconnection. It is demonstrated that the Rayleigh-Taylor instability of the nose of the heliopause creates consecutive layers of the interstellar and heliospheric plasma which are magnetically connected to different sources. This may be a possible explanation of abrupt changes in the galactic and anomalous cosmic ray fluxes observed by Voyager 1 when it was crossing the heliopause structure for a period of about one month in the summer of 2012. This paper also discusses the plausibility of fitting simulation results to a number of observational data sets obtained by in situ and remote measurements. The distribution of magnetic field in the vicinity of the heliopause is discussed in the context of Voyager measurements. It is argued that a classical heliospheric current sheet formed due to the Sun's rotation is not observed by in situ measurements and should not be expected to exist in numerical simulations extending to the boundary of the heliosphere. Furthermore, we discuss the transport of energetic particles in the inner and outer heliosheath, concentrating on the anisotropic spatial

  14. On the profile of energetic particles close upstream of interplanetary shocks: an easy task for THOR

    NASA Astrophysics Data System (ADS)

    Zimbardo, Gaetano; Perri, Silvia

    2017-04-01

    Collisionless shock waves are considered to be one of the main acceleration mechanisms for energetic particles in space and astrophysical plasmas. The most popular shock acceleration mechanisms, diffusive shock acceleration, is based on diffusive motion of energetic particles, but anomalous transport regimes, including subdiffusion and superdiffusion, are also possible. Here we present the extension of the well known Parker equation for the transport and acceleration of energetic particles and cosmic rays to the case of superdiffusion. The latter is modelled by means of fractional order derivatives of the particle distribution function, instead of the second order derivatives, on the spatial diffusion term. It is shown that the upstream steady state solution of the fractional Parker equation can be written in terms of the Mittag-Leffler functions, which generalize the standard exponential function, and correspond to stretched exponentials close to the shock, and to power laws far from the shock. Comparison of these solutions with available spacecraft data on interplanetary shocks shows that a much higher temporal resolution of energetic particle measurements is required, in order to be able to resolve the steep profile close upstream of the shock. Therefore, THOR high resolution measurements of energetic particle fluxes will allow a breakthrough in the understanding of energetic particle transport and acceleration.

  15. 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.

  16. EFFECT OF COHERENT STRUCTURES ON ENERGETIC PARTICLE INTENSITY IN THE SOLAR WIND AT 1 AU

    SciTech Connect

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

    2015-10-10

    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.

  17. 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.

  18. 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.

  19. 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.

  20. Early propagation of energetic particles across the mean field in turbulent plasmas

    NASA Astrophysics Data System (ADS)

    Laitinen, T.; Dalla, S.; Marriott, D.

    2017-09-01

    Propagation of energetic particles across the mean field direction in turbulent magnetic fields is often described as spatial diffusion. Recently, it has been suggested that initially the particles propagate systematically along meandering field lines, and only later reach the time-asymptotic diffusive cross-field propagation. In this paper, we analyse cross-field propagation of 1-100 MeV protons in composite 2D-slab turbulence superposed on a constant background magnetic field, using full-orbit particle simulations, to study the non-diffusive phase of particle propagation with a wide range of turbulence parameters. We show that the early-time non-diffusive propagation of the particles is consistent with particle propagation along turbulently meandering field lines. This results in a wide cross-field extent of the particles already at the initial arrival of particles to a given distance along the mean field direction, unlike when using spatial diffusion particle transport models. The cross-field extent of the particle distribution remains constant for up to tens of hours in turbulence environment consistent with the inner heliosphere during solar energetic particle events. Subsequently, the particles escape from their initial meandering field lines, and the particle propagation across the mean field reaches time-asymptotic diffusion. Our analysis shows that in order to understand solar energetic particle event origins, particle transport modelling must include non-diffusive particle propagation along meandering field lines.

  1. 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.

  2. 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.

  3. 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.

  4. Impact of Energetic-Particle-Driven Geodesic Acoustic Modes on Turbulence

    NASA Astrophysics Data System (ADS)

    Zarzoso, D.; Sarazin, Y.; Garbet, X.; Dumont, R.; Strugarek, A.; Abiteboul, J.; Cartier-Michaud, T.; Dif-Pradalier, G.; Ghendrih, Ph.; Grandgirard, V.; Latu, G.; Passeron, C.; Thomine, O.

    2013-03-01

    The impact on turbulent transport of geodesic acoustic modes excited by energetic particles is evidenced for the first time in flux-driven 5D gyrokinetic simulations using the Gysela code. Energetic geodesic acoustic modes (EGAMs) are excited in a regime with a transport barrier in the outer radial region. The interaction between EGAMs and turbulence is such that turbulent transport can be enhanced in the presence of EGAMs, with the subsequent destruction of the transport barrier. This scenario could be particularly critical in those plasmas, such as burning plasmas, exhibiting a rich population of suprathermal particles capable of exciting energetic modes.

  5. Impact of energetic-particle-driven geodesic acoustic modes on turbulence.

    PubMed

    Zarzoso, D; Sarazin, Y; Garbet, X; Dumont, R; Strugarek, A; Abiteboul, J; Cartier-Michaud, T; Dif-Pradalier, G; Ghendrih, Ph; Grandgirard, V; Latu, G; Passeron, C; Thomine, O

    2013-03-22

    The impact on turbulent transport of geodesic acoustic modes excited by energetic particles is evidenced for the first time in flux-driven 5D gyrokinetic simulations using the Gysela code. Energetic geodesic acoustic modes (EGAMs) are excited in a regime with a transport barrier in the outer radial region. The interaction between EGAMs and turbulence is such that turbulent transport can be enhanced in the presence of EGAMs, with the subsequent destruction of the transport barrier. This scenario could be particularly critical in those plasmas, such as burning plasmas, exhibiting a rich population of suprathermal particles capable of exciting energetic modes.

  6. 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.

  7. 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

  8. 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).

  9. Loss-cone instability: Wave saturation by particle trapping

    SciTech Connect

    Zaslavsky, A.; Krafft, C.; Volokitin, A.

    2007-12-15

    The nonlinear mechanisms governing the interactions between whistler or lower hybrid waves and loss-cone type particles' distributions in magnetized plasmas are of great importance if one considers the major role that waves of frequency below the electron cyclotron frequency play in space and thermonuclear fusion plasmas. Up to now, most of the numerical simulations have been devoted to study the nonlinear processes at work when the plasma is weakly relativistic and when the anisotropy of the particles' distributions leads to the so-called maser instability. However, in many interesting cases, the particles' energies are sufficiently weak to ensure the validity of the nonrelativistic approximation. In this framework, the paper studies the interaction at normal cyclotron resonances between lower hybrid waves and electron distributions presenting loss-cone like features. A theoretical Hamiltonian model and a corresponding numerical symplectic code are used to evidence and to explain the nonlinear mechanisms at work at the saturation stage of the loss-cone instability. Moreover, simple analytical expressions and scaling laws have been derived for the linear growth rates and the wave amplitude at saturation.

  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. 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

  12. 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

  13. 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.

  14. Energetic particle driven geodesic acoustic mode in a toroidally rotating tokamak plasma

    NASA Astrophysics Data System (ADS)

    Ren, Haijun

    2017-01-01

    Energetic particle (EP) driven geodesic acoustic modes (EGAMs) in toroidally rotating tokamak plasmas are analytically investigated using the hybrid kinetic-fluid model and gyrokinetic equations. By ignoring high-order terms and ion Landau damping, the kinetic dispersion relation is reduced to the hybrid one in the large safety factor limit. There is one high-frequency branch with a frequency larger than {ωt0} , the transit frequency of EPs with initial energy, which is always stable. Two low-frequency solutions with a frequency smaller than {ωt0} are complex conjugates in the hybrid limit. In the presence of ion Landau damping, the growth rate of the unstable branch is decreased and the damping rate of the damped branch is increased. The toroidal Mach number is shown to increase {{ Ω }\\text{r}} , the normalized real frequency of both branches. Although not affecting the instability critical condition, the Mach number decreases the growth rate when {{ Ω }\\text{r}} is larger than a critical value Ω \\text{r}\\text{cri} and enlarges the growth rate when {{ Ω }\\text{r}}< Ω \\text{r}\\text{cri} . The ion Landau damping effect is negligible for large M. But the discrepancy between the kinetic dispersion relation and the hybrid one becomes ignorable only for q≳ 7 .

  15. 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.

  16. Fluid electron, gyrokinetic ion simulations of linear internal kink and energetic particle modes

    NASA Astrophysics Data System (ADS)

    Cole, Michael; Mishchenko, Alexey; Könies, Axel; Kleiber, Ralf; Borchardt, Matthias

    2014-07-01

    The internal kink mode is an important plasma instability responsible for a broad class of undesirable phenomena in tokamaks, including the sawtooth cycle and fishbones. To predict and discover ways to mitigate this behaviour in current and future devices, numerical simulations are necessary. The internal kink mode can be modelled by reduced magnetohydrodynamics (MHD). Fishbone modes are an inherently kinetic and non-linear phenomenon based on the n = 1 Energetic Particle Mode (EPM), and have been studied using hybrid codes that combine a reduced MHD bulk plasma model with a kinetic treatment of fast ions. In this work, linear simulations are presented using a hybrid model which couples a fluid treatment of electrons with a gyrokinetic treatment of both bulk and fast ions. Studies of the internal kink mode in geometry relevant to large tokamak experiments are presented and the effect of gyrokinetic ions is considered. Interaction of the kink with gyrokinetic fast ions is also considered, including the destabilisation of the linear n = 1 EPM underlying the fishbone.

  17. Long-lasting energetic particle modes in tokamak plasmas with low magnetic shear

    NASA Astrophysics Data System (ADS)

    Zhang, Rui-Bin; Wang, Xian-Qu; Xiao, Chi-Jie; Wang, Xiao-Gang; Liu, Yi; Deng, Wei; Chen, Wei; Ding, Xuan-Tong; Duan, Xu-Ru; the HL-2 A Team

    2014-09-01

    A long-lasting (for hundreds of milliseconds) m/n = 1 energetic particle mode driven by trapped fast ions, other than conventional fishbone bursts, is studied theoretically and in comparison with HL-2A experimental results. The mode can be observed in weak shear tokamak plasmas during neutral beam injection with a mostly steady amplitude envelope of long-lasting magnetic perturbation signals. The dispersion relation and radial structure of the mode are calculated with a weak shear q-profile. Both the m/n = 1/1 component and its higher frequency m/n = 2/2 harmonics are found to be unstable, in good agreement with experimental observations on HL-2A. On the other hand, due to the feature of weak magnetic shear, the mode is also significantly different from bursty fishbones, especially the mode structure, temporal behavior, instability threshold and growth rate dependence on the fast ion gradient. The nonlinear evolution of the mode and the comparison with fishbone bursts are also further investigated.

  18. Fluid electron, gyrokinetic ion simulations of linear internal kink and energetic particle modes

    SciTech Connect

    Cole, Michael Mishchenko, Alexey; Könies, Axel; Kleiber, Ralf; Borchardt, Matthias

    2014-07-15

    The internal kink mode is an important plasma instability responsible for a broad class of undesirable phenomena in tokamaks, including the sawtooth cycle and fishbones. To predict and discover ways to mitigate this behaviour in current and future devices, numerical simulations are necessary. The internal kink mode can be modelled by reduced magnetohydrodynamics (MHD). Fishbone modes are an inherently kinetic and non-linear phenomenon based on the n = 1 Energetic Particle Mode (EPM), and have been studied using hybrid codes that combine a reduced MHD bulk plasma model with a kinetic treatment of fast ions. In this work, linear simulations are presented using a hybrid model which couples a fluid treatment of electrons with a gyrokinetic treatment of both bulk and fast ions. Studies of the internal kink mode in geometry relevant to large tokamak experiments are presented and the effect of gyrokinetic ions is considered. Interaction of the kink with gyrokinetic fast ions is also considered, including the destabilisation of the linear n = 1 EPM underlying the fishbone.

  19. The corrected NOAA/POES energetic particle database for space climate studies

    NASA Astrophysics Data System (ADS)

    Asikainen, T.; Maliniemi, V.; Mursula, K.

    2012-04-01

    When studying the effects of geomagnetic variability on the Earth's atmosphere reliable sources of quality long term data are essential. Most past studies concerning the effects of energetic particles precipitating from the magnetosphere into the atmosphere have been forced to use geomagnetic activity indices such as Kp (and Ap) as proxies for the intensity of this particle precipitation. Despite their good long term coverage these indices are only a crude proxy for the particle fluxes. Accordingly, there is a great need for a quality long term dataset of precipitating energetic particles. The polar orbiting NOAA/POES satellites have measured energetic particles with their MEPED instrument nearly continuously for more than 30 years. Up to now the reliable usage of the data has been severely restricted by several instrumental problems including degradation due to radiation damage, detector noise and contamination of electron measurements by protons. We have extensively studied these issues in the data and have now for the first time produced a new long term NOAA/MEPED database that corrects the data for all the above mentioned problems. Here we briefly review the problems that have plagued the NOAA/MEPED measurements and discuss the methods used to address them. We show how the corrections change the long term time series of the energetic particle fluxes dramatically. We will also discuss the relation between the energetic particle fluxes and geomagnetic indices to emphasize the difference between the two.

  20. 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.

  1. MMS Observations of Energetic Particle Escape Dynamics at the Dayside Magnetopause

    NASA Astrophysics Data System (ADS)

    Cohen, I. J.; Mauk, B.; Anderson, B. J.; Westlake, J. H.; Sibeck, D. G.; Fennell, J. F.; Blake, J. B.; Turner, D. L.; Baker, D. N.; Jaynes, A. N.; Spence, H. E.; Torbert, R. B.; Burch, J. L.

    2016-12-01

    Observations from the Energetic Particle Detector (EPD) instrument suite on the Magnetospheric Multiscale (MMS) spacecraft show that energetic (greater than tens of keV) magnetospheric particle escape into the magnetosheath occurs commonly, generally irrespective of conditions that engender reconnection and boundary-normal magnetic fields. Of great interest is the unexpectedly common simultaneous monohemispheric streaming of multiple species (electrons, H+, Hen+) in the dayside, dusk quadrant of the magnetosheath even though that region is thought to be drift-shadowed from energetic electrons. While processes leading to such monohemisperic streaming in the magnetosheath are possible with and without a boundary-normal magnetic field, statistical analysis of observations from MMS's first dayside magnetopause season show that energetic electron escape, in particular, occurs much more frequently during southward IMF. We also find that while energetic electron escape occurs across nearly all magnetic local times (MLT) on the dayside, a peak exists at approximately 15:00 MLT. We hypothesize that this may be correlated with the location where the draped interplanetary magnetic field lines nominally intersect with the dayside magnetosphere. In general, the apparent ubiquity of energetic electron escape at the dayside magnetopause implies that the dynamics of energetic particles in the outer magnetosphere are more complex than suggested by the static picture of magnetospheric drift-shadowing.

  2. Wear particles: Influence on local stress and dynamical instabilities

    NASA Astrophysics Data System (ADS)

    Nhu, Viet-Hung; Renouf, Mathieu; Massi, Francesco; Saulot, Aurélien

    2013-06-01

    When two continuous bodies are in contact and subjected to relative motion, both particle detachment and dynamic instabilities naturally occur. To properly model such interacting phenomena, it is required to take account for the discontinuity of the interfacial layer (usually modeled with Discrete Element Model) as well as the continuity of the bodies in contact (usually modeled with Finite Element Model). For that, the present paper aims at validating experimentally the coupled FEM-DEM method. The experimental set-up aims at modeling the frictional behavior between a holed disk, tied on its exterior side and made of transparent polymer with birefringence property, and an inner rotating cylinder, made of steel. This last is statically enlarged to reach the wanted contact pressure and then animated with constant angular velocity. The birefringence property of the disk is used to dynamically visualize the evolution of stresses in the disk at both contact scale and body scale. Based on the same principle with the same boundary conditions, the numerical model coupled the modeling of a deformable disk, a pseudo-rigid cylinder and wear particles by a combination of a finite element method and a discrete element method. Parametrical study has been numerically made to study the influence of particle morphology on stress evolution in the disk. A good agreement is showed between the numerical results obtained with particles artificially introduced in the contact and the experimental results obtained with wear particles naturally produced in the contact.

  3. Modification of Particle Distributions by MHD Instabilities II

    SciTech Connect

    Roscoe B. White

    2011-03-02

    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 in an island due to phase mixing and portions of phase space becoming stochastic lead to modification of the particle distribution, a process extremely rapid in the time scale of an experiment but still very long compared to the time scale of guiding center simulations. Large amplitude modes can cause profile avalanche and particle loss. Thus it is very valuable to be able to predict the temporal evolution of a particle distribution produced by a given spectrum of magnetohydrodynamic modes. In this paper we further develop and investigate the use of a new method of determining domains of phase space in which good KAM surfaces do not exist and use this method to examine a well documented case of profile modification by instabilities.

  4. On the relationship between collisionless shock structure and energetic particle acceleration

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.

    1983-01-01

    Recent experimental research on bow shock structure and theoretical studies of quasi-parallel shock structure and shock acceleration of energetic particles were reviewed, to point out the relationship between structure and particle acceleration. The phenomenological distinction between quasi-parallel and quasi-perpendicular shocks that has emerged from bow shock research; present efforts to extend this work to interplanetary shocks; theories of particle acceleration by shocks; and particle acceleration to shock structures using multiple fluid models were discussed.

  5. Relationship of solar flare accelerated particles to solar energetic particles (SEPs) observed in the interplanetary medium

    SciTech Connect

    Lin, R.P.

    2005-08-01

    Observations of hard X-ray (HXR)/gamma-ray continuum and gamma-ray lines produced by energetic electrons and ions, respectively, colliding with the solar atmosphere, have shown that large solar flares can accelerate ions up to many GeV and electrons up to hundreds of MeV. Solar energetic particles (SEPs) are observed by spacecraft near 1 AU and by ground-based instrumentation to extend up to similar energies, but these appear to be accelerated by shocks associated with fast Coronal Mass Ejections (CMEs). The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) mission provides high-resolution spectroscopy and imaging of flare HXRs and gamma-rays. Here we review RHESSI observations for large solar flares and SEP events. The 23 July gamma-ray line flare was associated with a fast, wide CME but no SEPs were observed, while the 21 April 2002 flare had no detectable gamma-ray line emission but a fast CME and strong SEP event were observed. The October- November 2003 series of large flares and associated fast CMEs produced both gamma-ray line emission and strong SEP events. The spectra of flare-accelerated protons, inferred from the gamma-ray line emission observed by RHESSI, is found to be essentially identical to the spectra of the SEPs observed near 1 AU for the well-connected 2 November and 20 January events.

  6. Energetic Particles inside Magnetic Clouds: a tentative search for their origin

    NASA Astrophysics Data System (ADS)

    Rodriguez-Pacheco, Javier

    During solar activity cycle 21st maximum, the instrumentation aboard ISEE-3 spacecraft observed many ener getic particles events, several of them associated with Magnetic Clouds (MCs). In this paper, we focus our study on the December 19th 1980 event, which was related with an MC that showed one of the most intense magnetic field strength ever observed. We have studied the energetic particle (36 keV - 1,6 MeV) spectra and directional distribution evolutions just before, inside and after the MC passage, with the aim of finding the origin of the energetic particles detected inside the MC.

  7. The interaction of energetic alpha-particles with intense lower hybrid waves

    SciTech Connect

    Fisch, N.J.; Rax, J.M.

    1992-06-01

    Lower hybrid waves are a demonstrated, continuous means of driving toroidal current in a tokamak. When these waves propagate in a tokamak fusion reactor, in which there are energetic {alpha}- particles, there are conditions under which the {alpha}-particles do not appreciably damp, and may even amplify, the wave, thereby enhancing the current-drive effect. Waves traveling in one poloidal direction, in addition to being directed in one toroidal direction, are shown to be the most efficient drivers of current in the presence of the energetic {alpha}-particles.

  8. The effect of energetic trapped particles on the ''ideal'' internal kink mode

    SciTech Connect

    Zhang, Y.Z.; Berk, H.L.; Mahajan, S.M.

    1988-12-01

    The internal kink stability of a tokamak in the presence of energetic particles is studied. It is found that there exists a stable window when a finite population of energetic particles are present, and the relation between the predictions of the fishbone theory of Chen-White-Rosenbluth and the fishbone theory of Coppi-Porcelli is explained. The theory indicates why some experiments, like PDX and TFTR, are likely to see fishbone oscillations in conjunction with sawtooth modes, while other experiments can observe sawtooth suppression in presence of hot particles. 14 refs., 3 figs., 2 tabs.

  9. Experimental Results of the Solar Energetic Particle Evens Inside Magnetic Clouds

    NASA Astrophysics Data System (ADS)

    Medina, J.; Hidalgo, M. A.

    2006-08-01

    The modulation effects of the solar ejecta over the solar energetic particle evens (0.5-100 MeV) 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. The experimental data from ACE, SAMPEX, SOHO, Ulysses and WIND satellites are presented, both from MC coincident with Solar particles evens (left figure) and not coincident (right figure). A simple model is proposed to explain this phenomenon. This work is performed inside COST Action 724.

  10. 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).

  11. PARTICLE TRAPPING AND STREAMING INSTABILITY IN VORTICES IN PROTOPLANETARY DISKS

    SciTech Connect

    Raettig, Natalie; Klahr, Hubert; Lyra, Wladimir E-mail: klahr@mpia.de

    2015-05-01

    We analyze the concentration of solid particles in vortices created and sustained by radial buoyancy in protoplanetary disks, e.g., baroclinic vortex growth. Besides the gas drag acting on particles, we also allow for back-reaction from dust onto the gas. This becomes important when the local dust-to-gas ratio approaches unity. In our two-dimensional, local, shearing sheet simulations, we see high concentrations of grains inside the vortices for a broad range of Stokes numbers, St. An initial dust-to-gas ratio of 1:100 can easily be reversed to 100:1 for St = 1.0. The increased dust-to-gas ratio triggers the streaming instability, thus counter-intuitively limiting the maximal achievable overdensities. We find that particle trapping inside vortices opens the possibility for gravity assisted planetesimal formation even for small particles (St = 0.01) and a low initial dust-to-gas ratio of 1:10{sup 4}, e.g., much smaller than in the previously studied magnetohydrodynamic zonal flow case.

  12. 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.

  13. 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

  14. Acceleration and transport of energetic particles from the sun to the outer heliosphere

    NASA Astrophysics Data System (ADS)

    Lee, Martin

    Energetic particles are a major constituent of the heliosphere. They consist of the galactic cosmic rays (GCRs), which penetrate the heliosphere from interstellar space, solar energetic particles (SEPs) produced by active regions at the Sun, and numerous populations accelerated within the heliosphere. They extend over the entire energy range from ~ 1 keV/nucleon characteristic of the solar wind to ~ GeV/nucleon energies of the GCRs and the highest energy SEPs. The energetic particle populations are both transient, such as SEPs, and approximately stationary, such as the energetic ions upstream of Earth’s bow shock. Most of these populations are directly or indirectly associated with shock waves, which are ubiquitous in the supersonic solar wind. In addition to the “diffuse,” “intermediate,” and “field aligned beam” distributions upstream of Earth’s bow shock, are similar distributions at the planets with strong magnetic fields, “energetic storm particle” events at interplanetary traveling shocks, and “corotating ion events” at corotating interaction regions in the solar wind. Although the pressure of these energetic particle enhancements is generally small compared with that of the solar wind, their pressure gradients can excite large enhancements of hydromagnetic waves, which in turn increase the rates of particle acceleration. Outstanding issues in shock acceleration are seed particle injection rates, acceleration at nearly perpendicular shocks, and the origin(s) of extreme variability in SEP event intensity. In addition to shocks, magnetic reconnection results in particle acceleration, notably of impulsive SEPs at the Sun, and solar wind compressions or turbulence may be responsible for partial acceleration of the “quiet time” suprathermal ion tails in the solar wind. Of particular current interest are the “termination shock particles” and “anomalous” cosmic rays, which are primarily accelerated at the solar wind termination

  15. 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.

  16. The Weibull functional form for the energetic particle spectrum at interplanetary shock waves

    NASA Astrophysics Data System (ADS)

    Laurenza, M.; Consolini, G.; Storini, M.; Pallocchia, G.; Damiani, A.

    2016-11-01

    Transient interplanetary shock waves are often associated with high energy particle enhancements, which are called energetic storm particle (ESP) events. Here we present a case study of an ESP event, recorded by the SEPT, LET and HET instruments onboard the STEREO B spacecraft, on 3 October 2011, in a wide energy range from 0.1 MeV to ∼ 30 MeV. The obtained particle spectrum is found to be reproduced by a Weibull like shape. Moreover, we show that the Weibull spectrum can be theoretically derived as the asymptotic steady state solution of the diffusion loss equation by assuming anomalous diffusion for particle velocity. The evaluation of Weibull's parameters obtained from particle observations and the power spectral density of the turbulent fluctations in the shock region, support this scenario and suggest that stochastic acceleration can contribute significantly to the acceleration of high energetic particles at collisioness shock waves.

  17. 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.

  18. 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.

  19. Gyrokinetic Simulation of Energetic Particles Turbulence and Transport in Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Wenlu; Lin, Zhihong; Holod, Ihor; Xiao, Yong; Bierwage, Andreas; Spong, Donald; Chu, Ming

    2009-05-01

    The confinement of the energetic particles (EP) is a critical issue in the International Thermonuclear Experimental Reactor (ITER), since that ignition relies on the self-heating by the fusion products. Shear Alfven wave excitations by EP in toroidal systems, for example Toroidal Alfven Eigenmode (TAE) and Energetic Particle Mode (EPM) have been investigated as primary candidate for fluctuation-induced transport of EP in fusion plasma. In this work, TAE excitations by energetic particles are investigated in large scale first-principle simulations of fusion plasmas using the global gyrokinetic toroidal code (GTC) [Lin, Science 1998]. Comprehensive linear benchmarking results are reported between GTC, GYRO, fluid code TAEFL, and Magnetohydrodynamic-gyrokinetic hybrid code HMGC.

  20. The atmospheric cosmic- and solar energetic particle radiation environment at aircraft altitudes.

    PubMed

    O'Brien, K; Friedberg, W; Smart, D F; Sauer, H H

    1998-01-01

    Galactic cosmic rays interact with the solar wind, the earth's magnetic field and hadron, lepton and photon fields at aircraft altitudes. In addition to cosmic rays, energetic particles generated by solar activity bombard the earth from time to time. These particles, while less energetic than cosmic rays, also produce radiation fields at aircraft altitudes which have qualitatively the same properties as atmospheric cosmic rays. We have used a code based on transport theory to calculate atmospheric cosmic-ray quantities and compared them with experimental data. Agreement with these data is seen to be good. We have then used this code to calculate equivalent doses to aircraft crews. We have also used the code to calculate radiation doses from several large solar energetic particle events which took place in 1989, including the very large event that occurred on September 29th and 30th of that year. The spectra incident on the atmosphere were determined assuming diffusive shock theory.

  1. Energetic protons, alpha particles, and electrons in magnetic flux transfer events

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Hovestadt, D.; Ipavich, F. M.; Gloeckler, G.

    1982-01-01

    Energetic proton, alpha particle, and electron data are presented for two magnetopause crossings, which show magnetic field signatures characteristic of flux transfer events (FTEs). Energetic proton and alpha particles are observed streaming along the magnetic field within the magnetosheath in all events showing magnetic signatures characteristic of the FTEs. Flux ratios as high as about 180 parallel and antiparallel to the magnetic field are observed, which means that ions of about 30 keV per charge are at times streaming almost scatter-free from the magnetopause into the magnetosheath. Energetic ion bursts with signatures equal to those observed in FTEs are reduced by more than an order of magnitude as compared to the trapped particle flux.

  2. 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

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

    NASA Astrophysics Data System (ADS)

    McComas, D. J.; Alexander, N.; Angold, N.; Bale, S.; Beebe, C.; Birdwell, B.; Boyle, M.; Burgum, J. M.; Burnham, J. A.; Christian, E. R.; Cook, W. R.; Cooper, S. A.; Cummings, A. C.; Davis, A. J.; Desai, M. I.; Dickinson, J.; Dirks, G.; Do, D. H.; Fox, N.; Giacalone, J.; Gold, R. E.; Gurnee, R. S.; Hayes, J. R.; Hill, M. E.; Kasper, J. C.; Kecman, B.; Klemic, J.; Krimigis, S. M.; Labrador, A. W.; Layman, R. S.; Leske, R. A.; Livi, S.; Matthaeus, W. H.; McNutt, R. L.; Mewaldt, R. A.; Mitchell, D. G.; Nelson, K. S.; Parker, C.; Rankin, J. S.; Roelof, E. C.; Schwadron, N. A.; Seifert, H.; Shuman, S.; Stokes, M. R.; Stone, E. C.; Vandegriff, J. D.; Velli, M.; von Rosenvinge, T. T.; Weidner, S. E.; Wiedenbeck, M. E.; Wilson, P.

    2016-12-01

    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 ˜20 keV/nucleon-15 MeV total energy and electrons from ˜25-1000 keV. EPI-Hi measures ions from ˜1-200 MeV/nucleon and electrons from ˜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 enable the

  4. The high energetic particles released during the decline phases of last five solar cycles

    NASA Astrophysics Data System (ADS)

    Hady, A. A., II

    2014-12-01

    During the decline phases of the last five solar cycles, new peak has appeared releasing high energetic particles. During October 2003 (so-called Halloween storms), a sudden increase of the solar activity occurred during the decline phase which has bigger than that occurred during the main peak of that Solar cycle 23. The same situation was repeated again for the solar cycle 24, during its decline phase, giving a new peak during January 2014 and release high energetic particles, which was bigger than that occurred during the mean peak of cycle 24. This means that the solar cycles starting from the cycle 20 have two peaks, the second peak always producing higher energetic flares which affects the Earth's magnetic field. The same situation happened in the cycles 21, and 22, but with lower release of energetic particle, compared with cycles 23 and 24. We will do descriptive studies of these events, according to data analysis, and compare the results. Keywords: Solar cycles; solar activities; solar energetic particles, Halloween storms, January 2014 storms.

  5. 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.

  6. 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.

  7. 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.

  8. The fate of meteoric metals in ice particles: Effects of sublimation and energetic particle bombardment

    NASA Astrophysics Data System (ADS)

    Mangan, T. P.; Frankland, V. L.; Murray, B. J.; Plane, J. M. C.

    2017-08-01

    The uptake and potential reactivity of metal atoms on water ice can be an important process in planetary atmospheres and on icy bodies in the interplanetary and interstellar medium. For instance, metal atom uptake affects the gas-phase chemistry of the Earth's mesosphere, and has been proposed to influence the agglomeration of matter into planets in protoplanetary disks. In this study the fate of Mg and K atoms incorporated into water-ice films, prepared under ultra-high vacuum conditions at temperatures of 110-140 K, was investigated. Temperature-programmed desorption experiments reveal that Mg- and K-containing species do not co-desorb when the ice sublimates, demonstrating that uptake on ice particles causes irreversible removal of the metals from the gas phase. This implies that uptake on ice particles in terrestrial polar mesospheric clouds accelerates the formation of large meteoric smoke particles (≥1 nm radius above 80 km) following sublimation of the ice. Energetic sputtering of metal-dosed ice layers by 500 eV Ar+ and Kr+ ions shows that whereas K reacts on (or within) the ice surface to form KOH, adsorbed Mg atoms are chemically inert. These experimental results are consistent with electronic structure calculations of the metals bound to an ice surface, where theoretical adsorption energies on ice are calculated to be -68 kJ mol-1 for K, -91 kJ mol-1 for Mg, and -306 kJ mol-1 for Fe. K can also insert into a surface H2O to produce KOH and a dangling H atom, in a reaction that is slightly exothermic.

  9. Experimental investigations of mechanical and reaction responses for drop-weight impacted energetic particles

    NASA Astrophysics Data System (ADS)

    Bao, Xiao-Wei; Wu, Yan-Qing; Wang, Ming-Yang; Huang, Feng-Lei

    2017-02-01

    Low-velocity drop-weight impact experiments on individual and multiple Cyclotetramethylene tetranitramine (HMX) energetic particles were performed using a modified drop-weight machine equipped with high-speed photography components. Multiple particles experienced more severe burning reactions than an individual particle. Comparisons between impacted salt and HMX particle show that jetting in HMX is mainly due to the motion of fragmented particles driven by gaseous reaction products. Velocity of jetting, flame propagation, and area expansion were measured via image processing, making it possible to quantify the chemical reaction or mechanical deformation violence at different stages.

  10. 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.

  11. Energetic particles and currents - results from Dynamics Explorer

    SciTech Connect

    Burch, J.L.

    1988-05-01

    The suprathermal plasma instruments on DE 1 and DE 2 (high-altitude plasma instrument, low-altitude plasma instrument, and energetic ion composition spectrometer) have provided new data on the distribution functions and composition of plasmas at altitudes from a few hundred to about 23,000 km. Of particular interest are the results that have been obtained on the injection and transport of plasma in the polar cusp, on the upward acceleration of ionospheric ions and electrons, and on the charge carriers of the various high-latitude Birkeland current systems (using independent measurements of the currents by the magnetic field instruments MAG-A and MAG-B). These results and other contributions of the Dynamics Explorer hot plasma and magnetic field measurements to the present understanding of magnetosphere-ionosphere coupling are reviewed in this paper. 90 references.

  12. Energetic particles and currents - Results from Dynamics Explorer

    NASA Astrophysics Data System (ADS)

    Burch, J. L.

    1988-05-01

    The suprathermal plasma instruments on DE 1 and DE 2 (high-altitude plasma instrument, low-altitude plasma instrument, and energetic ion composition spectrometer) have provided new data on the distribution functions and composition of plasmas at altitudes from a few hundred to about 23,000 km. Of particular interest are the results that have been obtained on the injection and transport of plasma in the polar cusp, on the upward acceleration of ionospheric ions and electrons, and on the charge carriers of the various high-latitude Birkeland current systems (using independent measurements of the currents by the magnetic field instruments MAG-A and MAG-B). These results and other contributions of the Dynamics Explorer hot plasma and magnetic field measurements to the present understanding of magnetosphere-ionosphere coupling are reviewed in this paper.

  13. Comparison of Solar Energetic Particle Flux Mapping Models

    NASA Astrophysics Data System (ADS)

    Young, S. L.; Roth, C. M.; Brodowski, C. M.; Kress, B. T.; Johnston, W. R.; Huston, S. L.; McCollough, J. P., II; Wilson, G.; Selesnick, R.

    2015-12-01

    Previous work using the Tsyganenko-Sitnov 2005 (TS05) magnetic field model combined withthe Dartmouth-CISM (DC) cutoff code to map GOES-7 SEM observations to CRRES locationshas demonstrated that, for reasonably static magnetospheric conditions, solar energetic particleobservations at GOES-7 can be mapped relatively accurately to locations inside of geosynchronouswhere L > 4.5. Also a good correlation with observations continues to approximately L = 3.5. Aprevious comparison of the TS05-DC combination with two other cutoff models found it to be themost accurate of the set when compared to SAMPEX observations in a LEO orbit. However, theTS05-DC combination requires significant computational resources compared to other models soit is important to quantify the difference in accuracy for operational purposes. In this study wecharacterize the Smart and Shea (SS) cutoff code and the Selesnick-Neal-Ogliore (SNO) model andcompare them to the TS05-DC cutoff model.

  14. Investigating The Ionization of The Earth's Atmosphere At Large Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Wolff, E.; Burrows, J.; Kallenrode, M.-B.; von König, M.; Künzi, K. F.; Quack, M.

    To investigate the influence of energetic particle events on the terrestrial atmosphere (e.g. due to ionization and/or hadronic interaction) a number of aspects are under consideration, such as the species of the precipitating particles, their energies, fluences as well as a repetition rate of events. In preparation of a refined model of precipitating charged particle interactions with the atmosphere, we calculate the ionization in the earth's atmosphere for well- known recent events (e.g. the Bastille Day event on July 14, 2000) of high particle fluences by using computer simulations of the earth's atmosphere and in situ measured particle intensities. The changes in atmospheric chemistry derieved from this ionization are described in the accompanying contribution of M. von König et al. (Modelling the influence of large energetic particle events on the chemical composition of the middle and upper atmosphere). Although very effective for atmospheric chemistry, these events are too rare and too short-lived to contribute significantly to the atmospheric NOx budget on a long-time basis. However, McCracken et al. (2001) suggests from nitrate depositions in ice- cores that solar particle events have occured more frequently and with a higher in- tensity in historical times, and thus may have led to a greater impact than the events discussed above. Therefore, we evaluate the influence of large historical energetic particle events, such as NOx and Ozone behaviour due to atmospheric ionization at Carrington's white light flare in 1859.

  15. 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

  16. 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.

  17. Energetic Particles from Outside our Solar System Increase Artist Concept

    NASA Image and Video Library

    2011-12-16

    This artist concept shows NASA Voyager 1 spacecraft in a new region at the edge of our solar system where the amount of high-energy particles diffusing into our solar system from outside has increased.

  18. On the acceleration of energetic particles in the interplanetary medium

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.

    1976-01-01

    Fermi scattering and transit time damping are two possible mechanisms for accelerating low energy protons (approximately 1 Mev) in co-rotating particle streams. Solutions to the equations which govern particle behavior in such streams are presented. It was found that acceleration by Fermi scattering requires a scattering mean-free path more than an order of magnitude smaller than the nominal value for low energy particles of 0.1 AU. Transit time damping of only the observed low level of magnitude fluctuations in the interplanetary magnetic field appears to yield the required acceleration rate. Measurements of the direction of the anisotropy in the particle streams could help in deciding which mechanism is operative. In the case of Fermi scattering the anisotropy must be in the heliocentric radial direction, whereas for transit time damping a significant azimuthal anisotropy could be present.

  19. 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.

  20. The effect of energetic particle induced geodesic acoustic modes on microturbulence

    NASA Astrophysics Data System (ADS)

    Schneller, Mirjam; Fu, Guoyong; Wang, Weixing; Chavdarovski, Ilija; Lauber, Philipp

    2016-10-01

    The control of turbulent transport reveals essential to achieve a successful fusion reactor. Together with turbulence, energetic particles are ubiquitous in present and future tokamaks due to heating systems and fusion reactions. Anisotropy in the distribution function of the energetic particle population is able to excite oscillations from the continuous spectrum of geodesic acoustic modes, which cannot be driven by plasma pressure gradients due to their toroidally and nearly poloidally symmetric structures. These oscillations are known as energetic particle-induced geodesic acoustic modes (EGAMs) [G.Y.Fu'08] and have been observed in recent experiments [R.Nazikian'08]. EGAMs are particularly attractive in the framework of turbulence regulation, since they lead to an oscillatory radial electric shear which can potentially saturate the turbulence. In recent years, numerical simulations have shown however, that turbulent transport could also be enhanced in the presence of EGAMs [D.Zarzoso'13]. For the presented work, the nonlinear gyrokinetic, electrostatic, particle-in-cell code GTS [W.X.Wang'06] has been extended to include an energetic particle population. With this new tool, the interaction of EGAMs with microturbulence is investigated in more detail. NERSC computing time is greatfully acknowledged.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. Energetic Particle Transport in Compact Quasi-axisymmetric Stellarators

    SciTech Connect

    Redi, M.H.; Mynick, H.E.; Suewattana, M.; White, R.B.; Zarnstorff, M.C.; Isaev, M.Yu.; Mikhailov, M.I.; Subbotin, A.A.

    1999-03-01

    Hamiltonian coordinate, guiding-center code calculations of the confinement of suprathermal ions in quasi-axisymmetric stellarator (QAS) designs have been carried out to evaluate the attractiveness of compact configurations which are optimized for ballooning stability. A new stellarator particle-following code is used to predict ion loss rates and particle confinement for thermal and neutral beam ions in a small experiment with R = 145 cm, B = 1-2 T and for alpha particles in a reactor-size device. In contrast to tokamaks, it is found that high edge poloidal flux has limited value in improving ion confinement in QAS, since collisional pitch-angle scattering drives ions into ripple wells and stochastic field regions, where they are quickly lost. The necessity for reduced stellarator ripple fields is emphasized. The high neutral beam ion loss predicted for these configurations suggests that more interesting physics could be explored with an experiment of less constrained size and magnetic field geometry.

  6. 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.

  7. 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.

  8. Pitch angle scattering of an energetic magnetized particle by a circularly polarized electromagnetic wave

    SciTech Connect

    Bellan, P. M.

    2013-04-15

    The interaction between a circularly polarized wave and an energetic gyrating particle is described using a relativistic pseudo-potential that is a function of the frequency mismatch. Analysis of the pseudo-potential provides a means for interpreting numerical results. The pseudo-potential profile depends on the initial mismatch, the normalized wave amplitude, and the initial angle between the wave magnetic field and the particle perpendicular velocity. For zero initial mismatch, the pseudo-potential consists of only one valley, but for finite mismatch, there can be two valleys separated by a hill. A large pitch angle scattering of the energetic electron can occur in the two-valley situation but fast scattering can also occur in a single valley. Examples relevant to magnetospheric whistler waves show that the energetic electron pitch angle can be deflected 5 Degree-Sign towards the loss cone when transiting a 10 ms long coherent wave packet having realistic parameters.

  9. 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.

  10. 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.

  11. Mapping the flow of energetic particles in Titan's exobase

    NASA Astrophysics Data System (ADS)

    Regoli, L.; Feyerabend, M.; Kotova, A.; Roussos, E.; Jones, G.; Krupp, N.; Coates, A.

    2014-04-01

    In this contribution, we present maps of the exobase of Titan, indicating the latitudes and longitudes at which energy deposition is expected from particles of different species and energies. For this, particle tracing software is used, using starting positions all around the moon at an altitude of 1450 km and backtracing them, varying the starting pitch and phase angles, as well as their energy. For this contribution, the T9 flyby by Cassini is considered, with the near-Titan electromagnetic environment modelled by the A.I.K.E.F. hybrid code, accounting for the distortions in the Saturnian magnetic field introduced by the presence of Titan with its conducting ionosphere.

  12. Linear and nonlinear dynamics of Alfven modes driven by energetic particles

    SciTech Connect

    Vlad, G.; Briguglio, S.; Romanelli, F.; Zonca, F.

    1996-12-31

    The understanding of the stability of global Alfven eigenmodes in the presence of energetic particles has been recognized to be very important in evaluating the success of the next step generation of thermonuclear fusion devices. The mode stability depends strongly on the spatial localization of the mode, being typically damped in the internal part of the discharge by Ion Landau Damping and being driven unstable if the mode is localized around 9 the maximum value of the pressure gradient of the energetic particles. Thus, the fully 2-D structure of the eigenmode is required in order to properly assess the issue of global Alfven modes stability, as, e.g., the Toroidal Alfven Eigenmodes (TAE). Furthermore, for realistic parameters, the effect of the drive and damping terms, as well as finite orbit widths of energetic particles and bulk-ions finite Larmor radius effects, cannot be treated perturbatively but should be considered at the same order as that at which toroidicity enters. The linear stability of TAE, Kinetic TAE (KTAE), and Energetic Particle continuum Mode (EPM) is studied using a code which solves the two-dimensional mode structure and global stability, in the limit of high toroidal mode number n, using a two spatial-scale WKBJ formalism treating drive and damping terms non-perturbatively. The nonlinear dynamics of these modes is studied by means a hybrid MHD-gyrokinetic particle simulation code. The code is able to treat low and moderately low toroidal mode number n. Nonperturbative treatment of the finite drift-orbit effects has been found to be crucial. It has been found that for typical parameters, the KTAE is indeed more unstable than the TAR In particular, in the nonlinear phase, the EPM is found to be particularly dangerous, leading to the expulsion of the energetic particles from the plasma column.

  13. 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.

  14. Energetic Particle Data From the Global Positioning System Constellation

    NASA Astrophysics Data System (ADS)

    Morley, S. K.; Sullivan, J. P.; Carver, M. R.; Kippen, R. M.; Friedel, R. H. W.; Reeves, G. D.; Henderson, M. G.

    2017-02-01

    Since 2000, Los Alamos National Laboratory (LANL) Combined X-ray and Dosimeter (CXD) and Burst Detector Dosimeter for Block II-R (BDD-IIR) instruments have been fielded on Global Positioning System (GPS) satellites. Today, 21 of the 31 operational GPS satellites are equipped with a CXD detector and a further 2 carry a BDD-IIR. Each of these instruments measures a wide range of energetic electrons and protons. These data have now been publicly released under the terms of the Executive Order for Coordinating Efforts to Prepare the Nation for Space Weather Events. The specific goal of releasing space weather data from the GPS satellites is to enable broad scientific community engagement in enhancing space weather model validation and improvements in space weather forecasting and situational awareness. The time period covered by this data release is approximately 16 years, which corresponds to more than 167 satellite years of data. The large number of GPS satellites, distributed over six orbital planes, will provide important context for ongoing and historical science missions, as well as enabling new types of research not previously possible.

  15. Energetic charged particles in the magnetosphere of Neptune

    SciTech Connect

    Stone, E.C.; Cummings, A.C.; Looper, 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 ({approx lt}1 megaelectron volt (MeV)) trapped electrons and protons in the magnetosphere of Neptune. The intensities at 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.

  16. Energetic charged particles in the magnetosphere of Neptune

    NASA Technical Reports Server (NTRS)

    Stone, E. C.; Cummings, A. C.; Looper, M. D.; Selesnick, R. S.; Lal, N.; Mcdonald, F. B.; Trainor, J. H.

    1989-01-01

    The Voyager 2 cosmic ray system (CRS) measured significant fluxes of energetic greater than or equal to about 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.

  17. Geomagnetically trapped, albedo and solar energetic particles: Trajectory analysis and flux reconstruction with PAMELA

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

    The PAMELA satellite experiment is providing comprehensive observations of the interplanetary and magnetospheric radiation in the near-Earth environment. Thanks to its identification capabilities and the semi-polar orbit, PAMELA is able to precisely measure the energetic spectra and the angular distributions of the different cosmic-ray populations over a wide latitude region, including geomagnetically trapped and albedo particles. Its observations comprise the solar energetic particle events between solar cycles 23 and 24, and the geomagnetic cutoff variations during magnetospheric storms. PAMELA's measurements are supported by an accurate analysis of particle trajectories in the Earth's magnetosphere based on a realistic geomagnetic field modeling, which allows the classification of particle populations of different origin and the investigation of the asymptotic directions of arrival.

  18. 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.

  19. Influence of resistivity on energetic trapped particle-induced internal kink modes

    SciTech Connect

    Biglari, H.; Chen, L.

    1986-01-01

    The influence of resistivity on energetic trapped particle-induced internal kink modes, dubbed ''fishbones'' in the literature, explored. A general dispersion relation, which recovers the ideal theory in its appropriate limit, is derived and analyzed. Implications of the theory for present generation fusion devices such as the Joint European Torus are discussed. 8 refs., 2 figs.

  20. 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.

  1. Laser-plasma energetic particle production for aneutronic nuclear fusion experiments

    NASA Astrophysics Data System (ADS)

    Giulietti, D.; Andreoli, P.; Batani, D.; Bonasera, A.; Boutoux, G.; Burgy, F.; Cipriani, M.; Consoli, F.; Cristofari, G.; De Angelis, R.; Di Giorgio, G.; Ducret, J. E.; Ingenito, F.; Jakubowska, K.; Verona, C.; Verona-Rinati, G.

    2017-07-01

    Protons at energies up to a few hundreds of keV have been accelerated, by irradiating thin Al foils with an intense, fs laser pulses. The produced energetic protons, directed on a massive natural Boron sample, induced (p + 11B) fusion reactions accompanied by alpha particles emission, detected by a CR39 plate.

  2. 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.

  3. 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.

  4. 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)].

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

    NASA Astrophysics Data System (ADS)

    Zonca, Fulvio; Chen, Liu

    2014-07-01

    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)].

  6. Distribution of energetic particles and secondary radiation according to orbital station "MIR" data obtained in 1991.

    PubMed

    Dmitriev, A; Kuznetsov, S; Shavrin, P; Lyagushin, V; Nechaev, O; Panasyuk, M; Tolstaya, E; Nikiforova, M

    1998-01-01

    A set of instruments for measuring energetic particle fluxes, containing two neutron detectors under different plexiglas shielding thicknesses, a scintillation detector, measuring energy release >0.1 MeV and 0.5 MeV and a Geiger counter were launched onboard OS 'MIR'. The latitude dependencies of the cosmic ray measurements were obtained and studied. The distributions of primary particle fluxes (protons and elections) as well as secondary particle fluxes (bremsstrahlung gamma-rays and neutrons) produced in interactions of radiation belt particles with the station materials were obtained. The electron belt, generated during the storm of March 24 1991, is studied.

  7. Energetic Particle Mean Free Path in the Wave Heated Solar Wind

    NASA Astrophysics Data System (ADS)

    Vainio, R. O., Laitinen, T.; Fichtner, H.

    2003-07-01

    We present simple analytical expressions for the power spectrum of cascading Alfv´n waves and the resulting solar energetic particle (SEP) mean free e path in the solar wind. The model can repro duce the short coronal mean free path required for efficient acceleration of SEPs in coronal shock waves as well as a longer interplanetary mean free path required for a rapid propagation of the accelerated particles to 1 AU.

  8. Understanding and Quantifying the Reactivity of Energetic NanoParticles and NanoComposites

    DTIC Science & Technology

    2015-01-05

    Aerosol Synthesis and Reactivity of Thin Oxide Shell Aluminum Nanoparticles via Fluorocarboxylic Acid Functional Coating, Particle & Particle...Received Paper G. Feng,, S. Chowdhury, G. Jian,, M.R Zachariah. Modified Aerosol Routes to Core-Shell Nano-Energetic Materials Synthesis , Materials...Hydride (- AlH3 ) was also conducted. In this study the ignition characteristics were determined through the use of two separate modified T-jump

  9. 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.

  10. 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.

  11. Ripple-induced energetic particle loss in tokamaks

    NASA Astrophysics Data System (ADS)

    White, R. B.; Goldston, R. J.; Redi, M. H.; Budny, R. V.

    1996-08-01

    The threshold for stochastic transport of high energy trapped particles in a tokamak due to toroidal field ripple is calculated by explicit construction of primary resonances, and a numerical examination of the route to chaos. Critical field ripple amplitude is determined for loss. The expression is given in magnetic coordinates and makes no assumptions regarding shape or up-down symmetry. An algorithm is developed including the effects of prompt axisymmetic orbit loss, ripple trapping, convective banana flow, and stochastic ripple loss, which gives accurate ripple loss predictions for representative Tokamak Fusion Test Reactor [R. Hawryluk, Plasma Phys. Controlled Fusion 33, 1509 (1991)] and International Thermonuclear Experimental Reactor [K. Tomabechi, Proceedings of the 12th International Conference on Plasma Physics and Controlled Nuclear Fusion Research (International Atomic Energy Agency, Vienna, 1989), Vol. 3, p. 214] equilibria. The algorithm is extended to include the effects of collisions and drag, allowing rapid estimation of alpha particle loss in tokamaks.

  12. 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.

  13. Stellar energetic particle ionization in protoplanetary disks around T Tauri stars

    NASA Astrophysics Data System (ADS)

    Rab, Ch.; Güdel, M.; Padovani, M.; Kamp, I.; Thi, W.-F.; Woitke, P.; Aresu, G.

    2017-07-01

    Context. Anomalies in the abundance measurements of short lived radionuclides in meteorites indicate that the protosolar nebulae was irradiated by a large number of energetic particles (E ≳ 10 MeV). The particle flux of the contemporary Sun cannot explain these anomalies. However, similar to T Tauri stars the young Sun was more active and probably produced enough high energy particles to explain those anomalies. Aims: We aim to study the interaction of stellar energetic particles with the gas component of the disk (i.e. ionization of molecular hydrogen) and identify possible observational tracers of this interaction. Methods: We used a 2D radiation thermo-chemical protoplanetary disk code to model a disk representative for T Tauri stars. We used a particle energy distribution derived from solar flare observations and an enhanced stellar particle flux proposed for T Tauri stars. For this particle spectrum we calculated the stellar particle ionization rate throughout the disk with an accurate particle transport model. We studied the impact of stellar particles for models with varying X-ray and cosmic-ray ionization rates. Results: We find that stellar particle ionization has a significant impact on the abundances of the common disk ionization tracers HCO+ and N2H+, especially in models with low cosmic-ray ionization rates (e.g. 10-19 s-1 for molecular hydrogen). In contrast to cosmic rays and X-rays, stellar particles cannot reach the midplane of the disk. Therefore molecular ions residing in the disk surface layers are more affected by stellar particle ionization than molecular ions tracing the cold layers and midplane of the disk. Conclusions: Spatially resolved observations of molecular ions tracing different vertical layers of the disk allow to disentangle the contribution of stellar particle ionization from other competing ionization sources. Modelling such observations with a model like the one presented here allows to constrain the stellar particle flux in

  14. The effect of injection location on the spectrum of energetic magnetospheric particles

    NASA Technical Reports Server (NTRS)

    Birmingham, T. J.

    1980-01-01

    The role of local particle injections and accelerations in determining energetic particle spectra used as an indication of the radial diffusion of trapped magnetospheric particles is assessed. An idealized one-dimensional steady-state model of magnetospheric radial transport in which diffusion is balanced against particle sources and sinks is used to illustrate the effects of particle injection at a point and over a band of radii in which the observation point is immersed in particle spectra. For an injection spectrum uniformly distributed in space and a step function in energy, it is shown that the energy dependence of the measured spectrum is determined not only by adiabatic energization of the input spectrum but by the spatial structure of the injection and the radial dependence of the diffusion coefficient as well. The relevance of the results for observations of particle spectra in the terrestrial and Jovian magnetospheres is also considered

  15. 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.

  16. Study and Analyze Energetic Particle and Magnetic Activity Data.

    DTIC Science & Technology

    1982-06-01

    and Vette, 1976) 111-1. The diameter distribution of etch pits of protons 95 111-2. Etch pit diameter ( D ) as a function of proton energy (E). 96 The...parameter on each curve represents etch time. 111-3. Etch pit diameter ( D ) as a function of bulk material 97 removed from one surface (Vgt) 111-4...curvature of plates d = plate separation (R1 - R2) Thus, the energy of particles passing through the exit aperture is directly proportional to the

  17. 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.

  18. 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.

  19. A filament of energetic particles near the high-latitude dawn magnetopause

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.; Williams, D. J.; Mcentire, R. W.; Christon, S. P.; Jacquey, C.; Angelopoulos, V.; Yamamoto, T.; Kokubun, S.; Frank, L. A.; Ackerson, K. L.

    1994-01-01

    The Geotail satelite detected a filament of tailward-streaming energetic particles spatially separated from the boundary layer of energetic particles at the high-latitude dawn magnetopause at a downstream distance of approximately 80 R(sub E) on October 27, 1992. During this event, the composition and charge states of energetic ions at energies above approximately 10 keV show significant intermix of ions from solar wind and ionospheric sources. Detailed analysis leads to the deduction that the filament was moving southward towards the neutral sheet at an average speed of approximately 80 km/s, implying an average duskward electric field of approximately 1 mV/m. Its north-south dimension was approximately 1 R(sub E) and it was associated with an earthward directed field-aligned current of approximately 5 mA/m. The filament was separated from the energetic particle boundary layer straddling the magnetopause by approximately 0.8 R(sub E) and was inferred to be detached from the boundary layer at downstream distance beyond approximately 70 R(sub E) in the distant tail.

  20. Parameter estimation for the superdiffusion of energetic particles upstream of heliospheric shocks

    NASA Astrophysics Data System (ADS)

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

    Recently, in-situ spacecraft observations have suggested that the diffusion of energetic particles accelerated at heliospheric shocks could be anomalous. In particular, a new technique of analysis has allowed to derive particle transport properties from energetic particle time profiles upstream of interplanetary shocks. Indeed, the time/spatial power-laws of the differential intensity far upstream of the shock are indicative of superdiffusion. Assuming spatial homogeneity of the background plasma, the power-law behaviour has been derived in principle both from a propagator formalism and a fractional transport equation. However, a precise determination of the key parameters, namely of the power-law index, the superdiffusion coefficient, and the related transition scale from a relatively flat spatial variation close to the shock to a steeper asymptotic power-law behaviour far upstream remains an open problem. We address this issue by studying typical shock observations and by comparing them to detailed modeling of superdiffusion.

  1. Quantifying Energetic Particle Precipitation using the Array for Broadband Observations of VLF/ELF Emissions (ABOVE)

    NASA Astrophysics Data System (ADS)

    Cully, C. M.

    2015-12-01

    The Array for Broadband Observations of VLF/ELF Emissions (ABOVE) is a network of instruments deployed across Western Canada to monitor electromagnetic emissions from 200 Hz to 75 kHz. By observing the amplitude and phase of artificial ground-based transmitters in this band, we monitor changes in lower D layer ionization caused by energetic particle precipitation. We discuss numerical modeling and sensitivity analyses that enable us to use ABOVE data to quantify energetic particle precipitation over Western Canada. We then apply this technique to precipitation events, comparing our preliminary results with in-situ and ground-based observations. We conclude that ABOVE offers a large-scale perspective on the problem of acceleration and loss of radiation belt particles that complements the detailed in-situ measurements from the Van Allen Probes, Themis, and other satellite missions.

  2. Solar energetic particle arrival at Mars due to the 27 January 2012 solar storm

    NASA Astrophysics Data System (ADS)

    Frahm, R. A.; Sharber, J. R.; Winningham, J. D.; Elliott, H. A.; Howard, T. A.; DeForest, C. E.; Odstrĉil, D.; Kallio, E.; McKenna-Lawlor, S.; Barabash, S.

    2013-06-01

    On January 27, 2012, an X-class flare brightened on the Sun at 18:15 UT. This event was associated with the generation of a high-energy stream of Solar Energetic Particles (SEPs) advancing along the Interplanetary Magnetic Field (IMF) which arrived at Mars in about 39 minutes. A Coronal Mass Ejection (CME) arrived at Mars several days later. The Electron Spectrometer (ELS), a part of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the European Mars Express (MEx) Spacecraft, associatively detected elevated background levels of penetrating particle radiation which abruptly increased above the baseline level by two orders of magnitude within several hours after first arrival, allowing the particle arrival time to be accurately determined from this gradual SEP. As Mars reacted to the SEP, the atmosphere heated driving expansion of the ionosphere.

  3. Type II and Type III Radio Emissions and Their Association with Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    It is well known that CME-driven shocks are a major source of solar energetic particles (SEPs). The solar phenomena associated with high energy SEP increases nearly always include type II radio emissions indicative of the presence of shocks. However, there is also a clear link between particles accelerated in the low corona and type III radio bursts. For the most energetic events the type III emissions extend into or occur after, the flare impulsive phase. Such emission has been named type III-l mainly because the emission is "late". In our work, we have found an excellent correlation between the pattern of radio emissions and the associated particle events. However, various other studies have investigated type III-l emissions and found the association with SEP events to be less compelling. We explore the results of these studies in order to determine why this is the case.

  4. 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.

  5. Energetic Charged Particles in Saturn's Magnetosphere: Voyager 2 Results.

    PubMed

    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 >/= 0.43-million-electron-volt proton flux was more intense, and both the proton and electron fluxes were more variable, 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 approximately 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.

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

    SciTech Connect

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

    1982-01-29

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

  7. Energetic charged particles in Saturn's magnetosphere - Voyager 2 results

    NASA Astrophysics Data System (ADS)

    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.

    1982-01-01

    Results from the cosmic-ray system on Voyager 2 in Saturn's magnetosphere are presented. During the inbound pass through the outer magnetosphere, the not less than 0.43-million-electron-volt proton flux was more intense, and both the proton and electron fluxes were more variable, 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 0.14to greater than 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 approximately 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.

  8. 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).

  9. Discovery of a new extragalactic population of energetic particles

    NASA Astrophysics Data System (ADS)

    Brown, Anthony M.; BÅ`hm, Céline; Graham, Jamie; Lacroix, Thomas; Chadwick, Paula; Silk, Joseph

    2017-03-01

    We report the discovery of a statistically significant hardening in the Fermi-LAT γ -ray spectrum of Centaurus A's (Cen A) core, with the spectral index hardening from Γ1=2.73 ±0.02 to Γ1=2.29 ±0.07 at a break energy of (2.6 ±0.3 ) GeV . Using a likelihood analysis, we find no evidence for flux variability in Cen A's core light curve above or below the spectral break when considering the entire 8 year period. Interestingly, however, the first ˜3.5 years of the low energy light curve shows evidence of flux variability at the ˜3.5 σ confidence level. To understand the origin of this spectral break, we assume that the low energy component below the break feature originates from leptons in Centaurus A's radio jet, and we investigate the possibility that the high energy component above the spectral break is due to an additional source of very high energy particles near the core of Cen A. We show for the first time that the observed γ -ray spectrum of an active galactic nucleus is compatible with either a very large localized enhancement (referred to as a spike) in the dark matter halo profile or a population of millisecond pulsars. Our work constitutes the first robust indication that new γ -ray production mechanisms can explain the emission from active galaxies and could provide tantalizing first evidence for the clustering of heavy dark matter particles around black holes.

  10. Multispacecraft observations of the east-west asymmetry of solar energetic storm particle events

    NASA Technical Reports Server (NTRS)

    Sarris, E. T.; Krimigis, S. M.

    1985-01-01

    Energetic proton observations have been obtained by instruments aboard the IMP-7 and -8 spacecraft and Voyager-1 and -2 deep space probes, in order to study the generation of solar flare Energetic Storm Particle Events (ESP) events at widely separated locations on the same shock front which are presumably characterized, on average, by different IMF shock front configurations for solar flare sites. Energetic proton observations indicate that substantial differences in the ESP proton intensity enhancements are detected at these energies for locations on the shock front with wide heliolongitude separations. The present results indicate that acceleration of ESP protons to more than 500 keV takes place at the quasi-perpendicular shock front domain, consistent with the 'shock drift' acceleration mechanism.

  11. Predicting dose-time profiles of solar energetic particle events using Bayesian forecasting methods.

    PubMed

    Neal, J S; Townsend, L W

    2001-12-01

    Bayesian inference techniques, coupled with Markov chain Monte Carlo sampling methods, are used to predict dose-time profiles for energetic solar particle events. Inputs into the predictive methodology are dose and dose-rate measurements obtained early in the event. Surrogate dose values are grouped in hierarchical models to express relationships among similar solar particle events. Models assume nonlinear, sigmoidal growth for dose throughout an event. Markov chain Monte Carlo methods are used to sample from Bayesian posterior predictive distributions for dose and dose rate. Example predictions are provided for the November 8, 2000, and August 12, 1989, solar particle events.

  12. Linear study of the precessional fishbone instability

    NASA Astrophysics Data System (ADS)

    Idouakass, M.; Faganello, M.; Berk, H. L.; Garbet, X.; Benkadda, S.

    2016-10-01

    The precessional fishbone instability is an m = n = 1 internal kink mode destabilized by a population of trapped energetic particles. The linear phase of this instability is studied here, analytically and numerically, with a simplified model. This model uses the reduced magneto-hydrodynamics equations for the bulk plasma and the Vlasov equation for a population of energetic particles with a radially decreasing density. A threshold condition for the instability is found, as well as a linear growth rate and frequency. It is shown that the mode frequency is given by the precession frequency of the deeply trapped energetic particles at the position of strongest radial gradient. The growth rate is shown to scale with the energetic particle density and particle energy while it is decreased by continuum damping.

  13. 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.

  14. The energetic charged particle absorption signature of Mimas. Progress report

    SciTech Connect

    Van Allen, J.A.; Thomsen, M.F.; Randall, B.A.

    1980-07-19

    Data are presented for a one-minute dip in electron intensity that was observed coherently by four different detectors at 1546:51 ERT on DOY 244/1979 as Pioneer 11 crossed the orbit of Mimas inbound during its encounter with the Saturn system. By a detailed analysis, we show that this absorption microsignature in electron intensity is plausibly attributable to the particle sweeping effect of Mimas; the radial width of the signature is caused primarily by energy dispersion in the longitudinal drift rate of electrons and not by radial diffusion; the spectrum of trapped electrons at Mimas is nearly monoenergetic, centered at kinetic energy E = 1.59 MeV with a spread delta E approx. 0.1 MeV; this narrow spectrum, which is unique in magnetospheric physics, is caused by the band-pass filtering action of the successive inner satellites, most importantly Enceladus, on an inward diffusing population of electrons; and the radial diffusion coefficient D of electrons E = 1.0 MeV is 1.0 x 10 to the -10 power R(subs)-squared at L = 4 and and probably in the range 37 to 8.3 10 to the -12 power R(subs)-squared at L = 3.

  15. Fragmentation energetics of clusters relevant to atmospheric new particle formation.

    PubMed

    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 (NPF), but basic species such as ammonia are also important. 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 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 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.

  16. 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.

  17. 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.

  18. Energetic particle signatures of magnetic field-aligned potentials over Jupiter's polar regions

    NASA Astrophysics Data System (ADS)

    Clark, G.; Mauk, B. H.; Haggerty, D.; Paranicas, C.; Kollmann, P.; Rymer, A.; Bunce, E. J.; Cowley, S. W. H.; Mitchell, D. G.; Provan, G.; Ebert, R. W.; Allegrini, F.; Bagenal, F.; Bolton, S.; Connerney, J.; Kotsiaros, S.; Kurth, W. S.; Levin, S.; McComas, D. J.; Saur, J.; Valek, P.

    2017-09-01

    Recent results of the first ever orbit through Jupiter's auroral region by NASA's Juno spacecraft did not show evidence of coherent acceleration in the auroral or polar region. However, in this letter, we show energetic particle data from Juno's Jupiter Energetic-particle Detector Instrument instrument during the third auroral pass that exhibits conclusive evidence of downward parallel electric fields in portions of Jupiter's polar region. The energetic particle distributions show inverted-V ion and electron structures in a downward electric current region with accelerated peaked distributions in hundreds of keV to 1 MeV range. The origin of these large electric potential structures is investigated and discussed within the current theoretical framework of current-voltage relationships at both Earth and Jupiter. Parallel electric fields responsible for accelerating particles to maintain the aurora/magnetospheric circuit appear to be a common phenomenon among strongly magnetized planets with conducting ionospheres; however, their origin and generation mechanisms are subjects of ongoing research.

  19. [A Generator of Mono-energetic Electrons for Response Test of Charged Particle Detectors.].

    PubMed

    Matsubayashi, Fumiyasu; Yoshida, Katsuhide; Maruyama, Koichi

    2005-01-01

    We designed and fabricated a generator of mono-energetic electrons for the response test of charged particle detectors, which is used to measure fragmented particles of the carbon beam for cancer therapy. Mono-energetic electrons are extracted from (90)Sr by analyzing the energy of beta rays in the generator with a magnetic field. We evaluated performance parameters of the generator such as the absolute energy, the energy resolution and the counting rates of extracted electrons. The generator supplies mono-energetic electrons from 0.5MeV to 1.7MeV with the energy resolution of 20% in FWHM at higher energies than 1.0MeV. The counting rate of electrons is 400cpm at the maximum when the activity of (90)Sr is 298kBq. The generator was used to measure responses of fragmented-particle detectors and to determine the threshold energy of the detectors. We evaluated the dependence of pulse height variation on the detector position and the threshold energy by using the generator. We concluded this generator is useful for the response test of general charged particle detectors.

  20. 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.

  1. 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.

  2. Prediction of Exposure Level of Energetic Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Kim, M. H. Y.; Blattnig, S.

    2016-12-01

    The potential for exposure to large solar particle events (SPEs) with fluxes that extend to high energies is a major concern during interplanetary transfer and extravehicular activities (EVAs) on the lunar and Martian surfaces. Prediction of sporadic occurrence of SPEs is not accurate for near or long-term scales, while the expected frequency of such events is strongly influenced by solar cycle activity. In the development of NASA's operational strategies real-time estimation of exposure to SPEs has been considered so that adequate responses can be applied in a timely manner to reduce exposures to well below the exposure limits. Previously, the organ doses of large historical SPEs had been calculated by using the complete energy spectra of each event and then developing a prediction model for blood-forming organ (BFO) dose based solely on an assumed value of integrated fluence above 30 MeV (Φ30) for an otherwise unspecified future SPE. While BFO dose is determined primarily by solar protons with high energies, it was reasoned that more accurate BFO dose prediction models could be developed using integrated fluence above 60 MeV (Φ60) and above 100 MeV (Φ100) as predictors instead of Φ30. In the current study, re-analysis of major SPEs (in which the proton spectra of the ground level enhancement [GLE] events since 1956 are correctly described by Band functions) has been used in evaluation of exposure levels. More accurate prediction models for BFO dose and NASA effective dose are then developed using integrated fluence above 200 MeV (Φ200), which by far have the most weight in the calculation of doses for deep-seated organs from exposure to extreme SPEs (GLEs or sub-GLEs). The unconditional probability of a BFO dose exceeding a pre-specified BFO dose limit is simultaneously calculated by taking into account the distribution of the predictor (Φ30, Φ60, Φ100, or Φ200) as estimated from historical SPEs. These results can be applied to the development of

  3. 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.

  4. Numerical simulations of solar energetic particle event timescales associated with ICMEs

    NASA Astrophysics Data System (ADS)

    Qi, Shi-Yang; Qin, Gang; Wang, Yang

    2017-03-01

    Recently, S. W. Kahler studied the timescales of solar energetic particle (SEP) events associated with coronal mass ejections (CMEs) from analysis of spacecraft data. They obtained different timescales for SEP events, such as TO, the onset time from CME launch to SEP onset, TR, the rise time from onset to half the peak intensity (0.5{I}{{p}}), and TD, the duration of the SEP intensity above 0.5{I}{{p}}. In this work, we solve the transport equation for SEPs considering interplanetary coronal mass ejection (ICME) shocks as energetic particle sources. With our modeling assumptions, our simulations show similar results to Kahler’s analysis of spacecraft data, that the weighted average of TD increases with both CME speed and width. Moreover, from our simulation results, we suggest TD is directly dependent on CME speed, but not dependent on CME width, which were not found in the analysis of observational data.

  5. Energetic Particle Modes: example of Autoresonance and Superradiance in fusion plasmas

    NASA Astrophysics Data System (ADS)

    Zonca, Fulvio; Chen, Liu

    2013-10-01

    Energetic Particle Modes (EPM) are resonant non-normal modes born out of the shear Alfvén wave (SAW) continuous spectrum when the energetic particle (EP) drive overcomes continuum damping in nonuniform fusion plasmas. Their nonlinear evolution is characterized by radially convective amplification of the EPM wave-packet and secular EP radial transports. Here, we demonstrate that EPM-EP phase locking is an example of Autoresonance in fusion plasmas; and that the corresponding EPM-EP nonlinear dynamics has interesting analogies with Superradiance. These complex nonlinear behaviors are described, in a simple yet practically relevant limiting case, by a complex Nonlinear Schrödinger Equation. Research support: ITER-CN, US DoE Grants and EURATOM/ENEA Contract of Association.

  6. 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.

  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. Detection of Lower Tropospheric Responses to Solar Energetic Particles at Midlatitudes

    NASA Astrophysics Data System (ADS)

    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.

  9. Detection of lower tropospheric responses to solar energetic particles at midlatitudes.

    PubMed

    Nicoll, K A; Harrison, R G

    2014-06-06

    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.

  10. 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.

  11. First results from the energetic particle instrument on the OEDIPUS-C sounding rocket

    NASA Astrophysics Data System (ADS)

    Gough, M. P.; Hardy, D. A.; James, H. G.

    The Canadian / US OEDIPUS-C rocket was flown from the Poker Flat Rocket Range November 6th 1995 as a mother-son sounding rocket. It was designed to study auroral ionospheric plasma physics using active wave sounding and prove tether technology. The payload separated into two sections reaching a separation of 1200m along the Earth's magnetic field. One section included a frequency stepped HF transmitter and the other included a synchronised HF receiver. Both sections included Energetic Particle Instruments, EPI, stepped in energy synchronously with the transmitter steps. On-board EPI particle processing in both payloads provided direct measurements of electron heating, wave-particle interactions via particle correlators, and a high resolution measurement of wave induced particle heating via transmitter synchronised fast sampling. Strong electron heating was observed at times when the HF transmitter frequency was equal to a harmonic of the electron gyrofrequency, f_ce, or equal to the upper hybrid frequency, f_uh.

  12. DRIFT ORBITS OF ENERGETIC PARTICLES IN AN INTERPLANETARY MAGNETIC FLUX ROPE

    SciTech Connect

    Krittinatham, W.; Ruffolo, D. E-mail: scdjr@mahidol.ac.t

    2009-10-10

    Interplanetary magnetic flux ropes have significant effects on the distribution of energetic particles in space. Flux ropes can confine solar energetic particles (SEPs) for hours, and have relatively low densities of Galactic cosmic rays (GCRs), as seen during second-stage Forbush decreases. As particle diffusion is apparently inhibited across the flux rope boundary, we suggest that guiding center drifts could play a significant role in particle motion into and out of the flux ropes. We develop an analytic model of the magnetic field in an interplanetary magnetic flux rope attached to the Sun at both ends, in quasi-toroidal coordinates, with the realistic features of a flux rope cross section that is small near the Sun, expanding with distance from the Sun, and field lines that are wound less tightly close to the Sun due to stretching by the solar wind. We calculate the particle drift velocity field due to the magnetic field curvature and gradient as a function of position and pitch-angle cosine, and trace particle guiding center orbits numerically, assuming conservation of the first adiabatic invariant. We find that SEPs in the interior of a flux rope can have drift orbits that are trapped for long times, as in a tokamak configuration, with resonant escape features as a function of the winding number. For Forbush decreases of GCRs, the drifts should contribute to a unidirectional anisotropy and net flow from one leg of the loop to the other, in a direction determined by the poloidal field direction.

  13. Propagation of Solar Energetic Particles Associated with Impulsive Solar Flares in Turbulent Interplanetary Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Guo, F.; Giacalone, J.

    2008-12-01

    We discuss the physics of the propagation of an impulsive release of charged particles in a turbulent magnetic field. Test-particle numerical simulations are used to study the propagation of solar energetic particles (SEPs) in interplanetary magnetic turbulence created by the random transverse motions of magnetic footpoints embedded in the solar atmosphere (Giacalone et al. 2006). The turbulence model includes a Kolmogorov-like magnetic field power spectrum containing a broad range of scales from those that lead to large-scale field-line random walk to small scales leading to resonant pitch-angle scattering of energetic particles. We relate our numerical simulations to spacecraft observations and show that a number of features of SEP events observed by ACE and Wind can be reproduced in these simulations. For instance, we find that,the path lengths traveled by particles are different from that expected for a simple Parker spiral; and thus. The resulting velocity dispersion is energy dependent. We also find flux dropouts associated with steep localized gradients. Moreover, since particles sample different field lines which have different path length, their arriving times are non-uniform.

  14. July 29, 2977 magnetic storm: observations and modeling of energetic particles at synchronous orbit

    SciTech Connect

    Baker, D.N.; Fritz, T.A.; Wilken, B.

    1981-01-01

    A brief description of the energetic particle studies carried out by Subgroup 6 of CDAW-2 is presented. Instrumentation onboard six spacecraft at (or near) geostationary orbit was used in the analysis. Timing of particle injection during the last, and largest, substorm on July 29, 1977 (approx. 1200 UT) was investigated, as was the particle phase space density variation associated with this event. Energetic proton gradient anisotropies were also used to examine large-scale magnetospheric boundary motions. Finally, adiabatic modeling calculations were performed for the substorm event period, including effects of injection, convection, corotation, and particle drifts. We find substantial evidence to suggest storage of solar wind-derived energy in the magnetotail prior to the substorm and we find this stored energy to be suddenly released at substorm expansion onset. We also find particles at geostationary orbit to be newly accelerated during the substorm to energies greater than or equal to 1 MeV (..mu.. greater than or equal to 100 MeV/G) and modeling shows that these particles could have been convected (and injected) from beyond 10 R/sub E/ in the nightside magnetosphere.

  15. 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.

  16. 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.

  17. 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.

  18. Isotope abundances of solar coronal material derived from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Stone, E. C.

    1989-01-01

    Coronal isotopic abundances for the elements He, C, N, O, Ne, and Mg are derived from previously published measurements of the isotopic composition of solar energetic particles by first measuring, and then correcting for, the charge-to-mass-dependent fractionation due to solar flare acceleration and propagation processes. The resulting coronal composition generally agrees with that of other samples of solar system material, but the previously noted difference between the solar flare and solar wind Ne-22/Ne-20 ratios remains unresolved.

  19. Diagnostics for energetic particle studies on the HL-2A tokamaka)

    NASA Astrophysics Data System (ADS)

    Yang, Q. W.; Yin, Z. J.; 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.; Cao, H. R.

    2014-11-01

    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.

  20. 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.

  1. Influence of resistivity on energetic trapped particle-induced internal kink modes

    SciTech Connect

    Biglari, H.; Chen, L.

    1986-06-01

    The influence of resistivity on energetic trapped particle-induced internal kink modes, dubbed ''fishbones'' in the literature, is explored. A general dispersion relation, which recovers the ideal theory in its appropriate limit, is derived and analyzed. An important implication of the theory for present generation fusion devices such as the Joint European Torus (Plasma Physics and Controlled Nuclear Fusion Research (IAEA, London, 1984), Vol I, p.11) is that they will be stable to fishbone activity.

  2. Numerical Investigation of the Preferential Concentration Instability of Particle Laden Homogeneous Shear

    NASA Astrophysics Data System (ADS)

    Kasbaoui, Mohamed; Koch, Donald; Desjardins, Olivier

    2015-11-01

    In a previous study (Kasbaoui et al., J. Fluid Mech. 2015), particle laden homogeneous shear was shown to be subject to an algebraic instability. Initially randomly distributed particles are entrained by wave-like perturbations in the fluid velocity and segregate in a similar wave-like pattern while they sediment under gravity. The preferential concentration mechanism, which is the tendency of particles to exit vortical regions and gather in straining regions, causes the two waves to amplify each other resulting in an algebraic instability. By means of simulations, we compare the perturbations growth to the one yielded by the theory in the limit of small Stokes number particles. The simulations are conducted with an Eulerian model of the particles as well as a Lagrangian model. The two are compared. A secondary Rayleigh-Taylor instability caused by the periodic stacking of heavy layers of concentrated particles on top of depleted lighter layers is analyzed.

  3. 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

  4. An Overview of Energetic Particle Measurements in the Jovian Magnetosphere with the EPAC Sensor on Ulysses.

    PubMed

    Keppler, E; Blake, J B; Fränz, M; Korth, A; Krupp, N; Quenby, J J; Witte, M; Woch, J

    1992-09-11

    Observations of ions and electrons of probable Jovian origin upstream of Jupiter were observed after a corotating interplanetary particle event. During the passage of Ulysses through the Jovian bow shock, magnetopause, and outer magnetosphere, the fluxes of energetic particles were surprisingly low. During the passage through the "middle magnetosphere," corotating fluxes were observed within the current sheet near the jovimagnetic equato. During the outbound pass, fluxes were variably directed; in the later part of the flyby, they were probably related to high-latitude phenomena.

  5. 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.

  6. Energetic particle modes of q = 1 high-order harmonics in tokamak plasmas with monotonic weak magnetic shear

    DOE PAGES

    Ren, Zhen-Zhen; Wang, Feng; Fu, G. Y.; ...

    2017-04-24

    Linear and nonlinear simulations of high-order harmonics q=1 energetic particle modes excited by trapped energetic particles in tokamaks are carried out using kinetic/magnetohydrodynamic hybrid code M3D-K. It is found that with a flat safety factor profile in the core region, the linear growth rate of high-order harmonics (m=n>1) driven by energetic trapped particles can be higher than the m/n=1/1 component. The high m=n>1 modes become more unstable when the pressure of energetic particles becomes higher. Moreover, it is shown that there exist multiple resonant locations satisfying different resonant conditions in the phase space of energetic particles for the high-order harmonicsmore » modes, whereas there is only one precessional resonance for the m/n=1/1 harmonics. The fluid nonlinearity reduces the saturation level of the n=1 component, while it hardly affects those of the high n components, especially the modes with m=n=3,4. The frequency of these modes does not chirp significantly, which is different with the typical fishbone driven by trapped particles. Lastly, in addition, the flattening region of energetic particle distribution due to high-order harmonics excitation is wider than that due to m/n=1/1 component, although the m/n=1/1 component has a higher saturation amplitude.« less

  7. Energetic particle modes of q = 1 high-order harmonics in tokamak plasmas with monotonic weak magnetic shear

    NASA Astrophysics Data System (ADS)

    Ren, Zhen-Zhen; Wang, Feng; Fu, G. Y.; Shen, Wei; Wang, Zheng-Xiong

    2017-05-01

    Linear and nonlinear simulations of high-order harmonics q = 1 energetic particle modes excited by trapped energetic particles in tokamaks are carried out using kinetic/magnetohydrodynamic hybrid code M3D-K. It is found that with a flat safety factor profile in the core region, the linear growth rate of high-order harmonics ( m = n > 1 ) driven by energetic trapped particles can be higher than the m / n = 1 / 1 component. The high m = n > 1 modes become more unstable when the pressure of energetic particles becomes higher. Moreover, it is shown that there exist multiple resonant locations satisfying different resonant conditions in the phase space of energetic particles for the high-order harmonics modes, whereas there is only one precessional resonance for the m / n = 1 / 1 harmonics. The fluid nonlinearity reduces the saturation level of the n = 1 component, while it hardly affects those of the high n components, especially the modes with m = n = 3 , 4 . The frequency of these modes does not chirp significantly, which is different with the typical fishbone driven by trapped particles. In addition, the flattening region of energetic particle distribution due to high-order harmonics excitation is wider than that due to m / n = 1 / 1 component, although the m / n = 1 / 1 component has a higher saturation amplitude.

  8. Statistical analysis of solar energetic particle events and related solar activity

    NASA Astrophysics Data System (ADS)

    Dierckxsens, Mark; Patsou, Ioanna; Tziotziou, Kostas; Marsh, Michael; Lygeros, Nik; Crosby, Norma; Dalla, Silvia; Malandraki, Olga

    2013-04-01

    The FP7 COMESEP (COronal Mass Ejections and Solar Energetic Particles: forecasting the space weather impact) project is developing tools for forecasting geomagnetic storms and solar energetic particle (SEP) radiation storms. Here we present preliminary results on a statistical analysis of SEP events and their parent solar activity during Solar Cycle 23. The work aims to identify correlations between solar events and SEP events relevant for space weather, as well as to quantify SEP event probabilities for use within the COMESEP alert system. The data sample covers the SOHO era and is based on the SEPEM reference event list [http://dev.sepem.oma.be/]. Events are subdivided if separate enhancements are observed in higher energy channels as defined for the list of Cane et al (2010). Energetic Storm Particle (ESP) enhancements during these events are identified by associating ESP-like increases in the proton channels with shocks detected in ACE and WIND data. Their contribution has been estimated and subtracted from the proton fluxes. Relationships are investigated between solar flare parameters such as X-ray intensity and heliographic location on the one hand, and the probability of occurrence and strength of energetic proton flux increases on the other hand. The same exercise is performed using the velocity and width of coronal mass ejections to examine their SEP productiveness. Relationships between solar event characteristics and SEP event spectral indices and fluences are also studied, as well as enhancements in heavy ion fluxes measured by the SIS instrument on board the ACE spacecraft during the same event periods. This work has received funding from the European Commission FP7 Project COMESEP (263252).

  9. Nonresonant Interaction of Charged Energetic Particles with Low-frequency Noncompressive Turbulence: Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Ragot, B. R.

    2012-10-01

    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° 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° 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° 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 fields at or near the gyroscale

  10. 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.

  11. Hot plasma and energetic particles in the earth's outer magnetosphere: new understandings during the IMS

    SciTech Connect

    Baker, D.N.; Fritz, T.A.

    1984-01-01

    In this paper we review the major accomplishments made during the IMS period in clarifying magnetospheric particle variations in the region from roughly geostationary orbit altitudes into the deep magnetotail. We divide our review into three topic areas: (1) acceleration processes; (2) transport processes; and (3) loss processes. Many of the changes in hot plasmas and energetic particle populations are often found to be related intimately to geomagnetic storm and magnetospheric substorm effects and, therefore, substantial emphasis is given to these aspects of particle variations in this review. The IMS data, taken as a body, allow a reasonably unified view as one traces magnetospheric particles from their acceleration source through the plasma sheet and outer trapping regions and, finally, to their loss via ionospheric precipitation and ring current formation processes. It is this underlying, unifying theme which is pursued here. 52 references, 19 figures.

  12. Observations of energetic particles with EPAC on Ulysses in polar latitudes of the heliosphere.

    PubMed

    Keppler, E; Fränz, M; Korth, A; Reuss, M K; Blake, J B; Seidel, R; Quenby, J J; Witte, M

    1995-05-19

    Measurements with the Energetic Particle Composition instrument (EPAC) aboard Ulysses show particles from near the ecliptic that were apparently accelerated by shocks associated with a corotating interaction region. The particles were detected together with the shocks and even when shocks no longer arrived at Ulysses up to -65 degrees of heliographic latitude but not beyond. Particles could have reached these latitudes along magnetic fields; such connections to the outer lower latitude heliosphere evidently do not exist above that latitude. The accelerated streams have composition similar to solar wind abundances, no dispersion, and a net inward anisotropy. The underlying composition between the recurrent stream is similar to the anomalous component of cosmic rays. The channel sensitive to high-energy protons (> 230 megaelectron volts) shows a 26-day variation of the flux superimposed on the heliospheric modulation of galactic ions.

  13. Local modulation and trapping of energetic particles by coherent magnetic structures

    NASA Astrophysics Data System (ADS)

    Tessein, Jeffrey A.; Ruffolo, David; Matthaeus, William H.; Wan, Minping

    2016-04-01

    Recent observational studies show strong statistical associations between features of interplanetary suprathermal energetic particle (EP) data and rapid changes in the interplanetary vector magnetic field. The latter are connected to intermittency and coherent magnetic structures, including classical discontinuities. Here we discuss these observations in the context of two appealing theoretical ideas: First, magnetic structures bounding flux tubes can cause local or temporary topological trapping, thus influencing EP transport. Second, charged particles may be accelerated by interacting with dynamic flux tubes, either through reconnection, trapping in secondary islands, or a betatron mechanism. We present observations that support interpretation in terms of trapping boundaries associated with changes in EP flux and also find a case in which an EP peak lies near a coherent magnetic structure that is not a shock, with changing particle anisotropy consistent with outflow from the structure, suggestive of local particle acceleration.

  14. Inverse Saffman-Taylor instability in Hele-Shaw experiments using micro-particles

    NASA Astrophysics Data System (ADS)

    Zoueshtiagh, Farzam; Bihi, Ilyesse; Butler, Jason; Faille, Christine; Baudoin, Michaël

    2016-11-01

    Saffman-Taylor instability can occur when a low viscosity fluid displaces one of higher viscosity. It results from the decrease of the flow resistance as the fluid of lower viscosity replaces the more viscous one. This Saffman-Taylor instability is revisited experimentally for the inverse case of a viscous fluid displacing air when partially wetting 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. We acknowledge the support from the Marie Curie International Research Staff Exchange Scheme Fellowship ("Patterns and Surfaces" No. 269207) within the 7th European Community Framework Programme.

  15. Study of energetic particle physics with advanced ECEI system on the HL-2A tokamak

    NASA Astrophysics Data System (ADS)

    Shi, Zhongbing; Jiang, Min; Yu, Liming; Chen, Wei; Shi, Peiwan; Zhong, Wulyu; Yang, Zengchen; Zhang, Boyu; Ji, Xiaoquan; Li, Yonggao; Zhou, Yan; Song, Shaodong; Huang, Mei; Song, Xianming; Li, Jiaxuan; Yuan, Baoshan; Fu, Bingzhong; Liu, Zetian; Ding, Xuantong; Xu, Yuhong; Yang, Qingwei; Duan, Xuru

    2017-07-01

    Understanding the physics of energetic particles (EP) is crucial for the burning plasmas in next generation fusion devices such as ITER. In this work, three types of internal kink modes (a saturated internal kink mode (SK), a resonant internal kink mode (RK), and a double e-fishbone) excited by energetic particles in the low density discharges during ECRH/ECCD heating have been studied by the newly developed 24(poloidal) × 16(radial) = 384 channel ECEI system on the HL-2A tokamak. The SK and RK rotate in the electron diamagnetic direction poloidally and are destabilized by the energetic trapped electrons. The SK is destabilized in the case of qmin > 1, while the RK is destabilized in the case of qmin < 1. The double e-fishbone, which has two m/n = 1/1 modes propagating in the opposite directions poloidally, has been observed during plasma current ramp-up with counter-ECCD. Strong thermal transfer and mode coupling between the two m/n = 1/1 modes have been studied.

  16. Uptake of Mg and K on ice: Effect of sublimation and energetic particle bombardment

    NASA Astrophysics Data System (ADS)

    Mangan, T.; Frankland, V.; Plane, J. M. C.

    2016-12-01

    Uptake of metals on water ice can occur in polar mesospheric clouds (PMCs) in the mesosphere of Earth, on icy bodies in space and in the interstellar medium (ISM). Uptake of metals on icy particles could have implications for the surface and gas phase chemistry of the mesosphere. While in the ISM, the interactions of metals with water ice could affect processes relating to the agglomeration of matter into planets. In this study we experimentally investigate Mg and K embedded in water ice. Mg and K dosed ice films were prepared under ultra-high vacuum conditions in the laboratory at temperatures ≤ 140 K. Metal dosed ice films were subjected to temperature programmed desorption (TPD) and energetic ion bombardment (Ar+ and Kr+). TPD experiments revealed that negligible Mg and K containing species were co-desorbed with the ice film. This was also previously observed for Fe and suggests that metals contained within sublimating PMC particles in the mesosphere (or Icy particles in the ISM) may not be released into the gas phase. Instead, the metallic species could coalesce leading to the formation of residual particles. Energetic sputtering of metal dosed ice layers by 500 eV energy Ar+ and Kr+ efficiently removed the metals and highlighted significant differences between the two regarding their distribution within the ice layer.

  17. 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.

  18. Energetic Charged-Particle Phenomena in the Jovian Magnetosphere: First Results from the Ulysses COSPIN Collaboration.

    PubMed

    Simpson, J A; Anglin, J D; Balogh, A; Burrows, J R; Cowley, S W; Ferrando, P; Heber, B; Hynds, R J; Kunow, H; Marsden, R G; McKibben, R B; Müller-Mellin, R; Page, D E; Raviart, A; Sanderson, T R; Staines, K; Wenzel, K P; Wilson, M D; Zhang, M

    1992-09-11

    The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes ( approximately 37 degrees south) on the dusk side and reached higher magnetic latitudes ( approximately 49 degrees north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of approximately 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include (i) an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium, (ii) high-energy electron bursts (rise times approximately 17 megaelectron volts) on the dusk side that are apparently associated with field-aligned currents and radio burst emissions, (iii) persistence of the global 10-hour relativistic electron "clock" phenomenon throughout Jupiter's magnetosphere, (iv) on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail, and (v) consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons.

  19. Global Positioning System Energetic Particle Data: The Next Space Weather Data Revolution

    NASA Technical Reports Server (NTRS)

    Knipp, Delores J.; Giles, Barbara L.

    2016-01-01

    The Global Positioning System (GPS) has revolutionized the process of getting from point A to point Band so much more. A large fraction of the worlds population relies on GPS (and its counterparts from other nations) for precision timing, location, and navigation. Most GPS users are unaware that the spacecraft providing the signals they rely on are operating in a very harsh space environment the radiation belts where energetic particles trapped in Earths magnetic field dash about at nearly the speed of light. These subatomic particles relentlessly pummel GPS satellites. So by design, every GPS satellite and its sensors are radiation hardened. Each spacecraft carries particle detectors that provide health and status data to system operators. Although these data reveal much about the state of the space radiation environment, heretofore they have been available only to system operators and supporting scientists. Research scientists have long sought a policy shift to allow more general access. With the release of the National Space Weather Strategy and Action Plan organized by the White House Office of Science Technology Policy (OSTP) a sample of these data have been made available to space weather researchers. Los Alamos National Laboratory (LANL) and the National Center for Environmental Information released a months worth of GPS energetic particle data from an interval of heightened space weather activity in early 2014 with the hope of stimulating integration of these data sets into the research arena. Even before the public data release GPS support scientists from LANL showed the extraordinary promise of these data.

  20. The surface distribution of solar energetic particles on the Earth and Southern Atlantic Anomaly

    NASA Astrophysics Data System (ADS)

    Trihermanto, Febi; Herdiwijaya, Dhani

    2012-06-01

    Solar Energetic Particle (SEP) is a high-energy particles of protons, electrons, and ions trapped in magnetic fields in the corona of the Sun. The particles can be ejected into interplanetary space and reach the Earth, through the propagation of magnetic flux tubes, as a result of energetic phenomena such as flares and Coronal Mass Ejection (CME). SEP-related phenomena that will be discussed in this paper is Southern Atlantic Anomaly (SAA), anomalous distribution of high energy particles trapped in Earth's magnetic field as well as its association with Van Allen radiation belts. Space, Environment, Effects, and Education System (SPENVIS), software developed by European Space Agency (ESA), is capable of displaying data on the distribution of protons (0.1-500 MeV) and electrons (0.1-5 MeV) trapped in Earth's magnetic field. The results show that distribution of electrons and protons depend on altitude (100-36000 km), their energies, and phase of solar cycle maximum and minimum.

  1. Aerosol particle charger and an SO/sub 2/ reactor using energetic electrons

    SciTech Connect

    Davis, R.H.

    1984-01-01

    Two properties of energetic electrons in gas, their high specific ionization and their production of radicals and other chemically active specie, have promising applications to the cleanup of flue gas from coal combustion. The copious ionization has been used in a test particle charger to electrically charge 1 and 3 ..mu..m particles for subsequent removal by electrostatic precipitation. Particle charge greater than 5 times the theoretical ionic charging value for 1 ..mu..m particles have been observed in a bi-electrode electron beam precharger in which the beam energy is matched with the electrode spacing. In another test device, pulsed streamer coronas have been used to release and to energize electrons which promote gas phase chemical reactions and remote sulfur dioxide from humid air with high efficiency. The energized electrons produce oxidant radicals and chemically active specie which convert the SO/sub 2/ into sulfuric acid mist. While reported separately here, the two applications of energetic electrons may be amenable to combination in an integrated system for the combined treatment of flue gas.

  2. 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.

  3. Energetic charged-particle phenomena in the Jovian magnetosphere - First results from the Ulysses COSPIN collaboration

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Anglin, J. D.; Balogh, A.; Burrows, J. R.; Cowley, S. W. H.; Ferrando, P.; Heber, B.; Hynds, R. J.; Kunow, H.; Marsden, R. G.

    1992-01-01

    The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes on the dusk side and reached higher magnetic latitudes on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of about 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium; high-energy electron bursts on the dusk side that are apparently associated with field-aligned currents and radio burst emissions; persistence of the global 10-hour relativistic electron 'clock' phenomenon throughout Jupiter's magnetosphere; on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail; and consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons.

  4. Global Positioning System Energetic Particle Data: The Next Space Weather Data Revolution

    NASA Technical Reports Server (NTRS)

    Knipp, Delores J.; Giles, Barbara L.

    2016-01-01

    The Global Positioning System (GPS) has revolutionized the process of getting from point A to point Band so much more. A large fraction of the worlds population relies on GPS (and its counterparts from other nations) for precision timing, location, and navigation. Most GPS users are unaware that the spacecraft providing the signals they rely on are operating in a very harsh space environment the radiation belts where energetic particles trapped in Earths magnetic field dash about at nearly the speed of light. These subatomic particles relentlessly pummel GPS satellites. So by design, every GPS satellite and its sensors are radiation hardened. Each spacecraft carries particle detectors that provide health and status data to system operators. Although these data reveal much about the state of the space radiation environment, heretofore they have been available only to system operators and supporting scientists. Research scientists have long sought a policy shift to allow more general access. With the release of the National Space Weather Strategy and Action Plan organized by the White House Office of Science Technology Policy (OSTP) a sample of these data have been made available to space weather researchers. Los Alamos National Laboratory (LANL) and the National Center for Environmental Information released a months worth of GPS energetic particle data from an interval of heightened space weather activity in early 2014 with the hope of stimulating integration of these data sets into the research arena. Even before the public data release GPS support scientists from LANL showed the extraordinary promise of these data.

  5. CORRECTING FOR INTERPLANETARY SCATTERING IN VELOCITY DISPERSION ANALYSIS OF SOLAR ENERGETIC PARTICLES

    SciTech Connect

    Laitinen, T.; Dalla, S.; Huttunen-Heikinmaa, K.; Valtonen, E.

    2015-06-10

    To understand the origin of Solar Energetic Particles (SEPs), we must study their injection time relative to other solar eruption manifestations. Traditionally the injection time is determined using the Velocity Dispersion Analysis (VDA) where a linear fit of the observed event onset times at 1 AU to the inverse velocities of SEPs is used to derive the injection time and path length of the first-arriving particles. VDA does not, however, take into account that the particles that produce a statistically observable onset at 1 AU have scattered in the interplanetary space. We use Monte Carlo test particle simulations of energetic protons to study the effect of particle scattering on the observable SEP event onset above pre-event background, and consequently on VDA results. We find that the VDA results are sensitive to the properties of the pre-event and event particle spectra as well as SEP injection and scattering parameters. In particular, a VDA-obtained path length that is close to the nominal Parker spiral length does not imply that the VDA injection time is correct. We study the delay to the observed onset caused by scattering of the particles and derive a simple estimate for the delay time by using the rate of intensity increase at the SEP onset as a parameter. We apply the correction to a magnetically well-connected SEP event of 2000 June 10, and show it to improve both the path length and injection time estimates, while also increasing the error limits to better reflect the inherent uncertainties of VDA.

  6. How Structures of the Solar Corona and Eruptions Interact to Create Extreme Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Evans, R. M.; Kozarev, K. A.; Zheng, Y.; Pulkkinen, A.; Taktakishvili, A.; Kuznetsova, M. M.; Opher, M.; Dayeh, M. A.; Schwadron, N. A.; van der Holst, B.

    2012-12-01

    As the Sun approaches maximum activity, the number of solar energetic particle (SEP) events is rapidly increasing. These strong events have the potential to damage technical systems, so it is essential to understand what causes them. Although relationships exist between the characteristics of SEP events and the associated flares and coronal mass ejections (CMEs), the strongest solar events may not lead to the most intense particle events. For example, the first Ground Level Enhancement event of Solar Cycle 24 was associated with only a moderately strong flare and CME. Presumably, there must be other factors that determine the acceleration of the highest energy particles. To address this question, we combine observations and innovative theoretical modeling of recent SEP events. We use a three-dimensional magnetohydrodynamics (MHD) model of the solar corona (within the Space Weather Modeling Framework) to simulate eruptions in the low to middle corona. The MHD output is coupled to a global kinetic simulation of particle acceleration and transport (within the Energetic Particle Radiation Environment Module). The output of the simulation is a synthetic spectral profile response to realistic solar corona conditions during the propagation of a CME. We study the evolution of the CME structures (shock and compression regions within the sheath) and the relation of these features to the preexisting coronal magnetic field geometry and solar wind distribution. Then we determine which factors affect the efficiency of particle acceleration and transport. For the first time, we can probe how particle acceleration varies in different regions of the CME as it interacts with the solar wind. R. M. E. is supported through an appointment to the NASA Postdoctoral Program at GSFC, administered by Oak Ridge Associated Universities through a contract with NASA.

  7. The 2012 July 23 Backside Eruption: An Extreme Energetic Particle Event?

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Yashiro, S.; Thakur, N.; Mäkelä, P.; Xie, H.; Akiyama, S.

    2016-12-01

    The backside coronal mass ejection (CME) of 2012 July 23 had a short Sun-to-Earth shock transit time (18.5 hr). The associated solar energetic particle (SEP) event had a >10 MeV proton flux peaking at ˜5000 pfu, and the energetic storm particle event was an order of magnitude larger, making it the most intense event in the space era at these energies. By a detailed analysis of the CME, shock, and SEP characteristics, we find that the July 23 event is consistent with a high-energy SEP event (accelerating particles to gigaelectronvolt energies). The times of maximum and fluence spectra in the range 10-100 MeV were very hard, similar to those of ground-level enhancement (GLE) events. We found a hierarchical relationship between the CME initial speeds and the fluence spectral indices: CMEs with low initial speeds had SEP events with the softest spectra, while those with the highest initial speeds had SEP events with the hardest spectra. CMEs attaining intermediate speeds result in moderately hard spectra. The July 23 event was in the group of hard-spectrum events. During the July 23 event, the shock speed (>2000 km s-1), the initial acceleration (˜1.70 km s-2), and the shock-formation height (˜1.5 solar radii) were all typical of GLE events. The associated type II burst had emission components from meter to kilometer wavelengths, suggesting a strong shock. These observations confirm that the 2012 July 23 event is likely to be an extreme event in terms of the energetic particles it accelerated.

  8. The 2012 July 23 Backside Eruption: An Extreme Energetic Particle Event?

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Yashiro, S.; Thakur, N.; Makela, P.; Xie, H.; Akiyama, S.

    2016-01-01

    The backside coronal mass ejection (CME) of 2012 July 23 had a short Sun-to-Earth shock transit time (18.5 hr).The associated solar energetic particle (SEP) event had a greater than