Banded structures in electron pitch angle diffusion coefficients from resonant wave-particle interactions

2016 ◽  
Vol 23 (4) ◽  
pp. 042101 ◽  
Author(s):  
A. K. Tripathi ◽  
R. P. Singhal ◽  
G. V. Khazanov ◽  
L. A. Avanov
Keyword(s):  
Diffusion Coefficients ◽  
Pitch Angle ◽  
Particle Interactions ◽  
Resonant Wave ◽  
Wave Particle Interactions

Statistical EMIC diffusion models calculated by averaging observation specific diffusion coefficients

2021 ◽  
Author(s):  
Johnathan Ross ◽  
Sarah Glauert ◽  
Richard Horne ◽  
Nigel Meredith ◽  
Clare Watt
Keyword(s):  
Diffusion Coefficients ◽  
Radiation Belt ◽  
Diffusion Models ◽  
Relativistic Electrons ◽  
Particle Interactions ◽  
Resonant Wave ◽  
Van Allen Probes ◽  
Through Diffusion ◽  
Wave Particle Interactions ◽  
Emic Waves

<p>Electromagnetic ion cyclotron (EMIC) waves play an important role in relativistic electron losses in the radiation belts through diffusion via resonant wave-particle interactions. We present a new statistical model of electron diffusion by EMIC waves calculated, using Van Allen Probe observations, by averaging observation specific diffusion coefficients. The resulting diffusion coefficients therefore capture a wider range of wave-particle interactions than previous average models which are calculated using average observations. These calculations, and their role in radiation belt simulations, are then compared against existing diffusion models. The new diffusion coefficients are found to significantly improve the agreement between the calculated decay of relativistic electrons and Van Allen Probes data.</p><p> </p>

scholarly journals Ring Current Proton Dynamics Driven by Wave-Particle Interactions During a Nonstorm Period

2021 ◽  
pp. 98-104
Author(s):  
Sergei V. Smolin
Keyword(s):  
Pitch Angle ◽  
Ring Current ◽  
Activity Index ◽  
Proton Flux ◽  
Angle Distribution ◽  
Particle Interactions ◽  
Pitch Angle Distribution ◽  
Ion Cyclotron ◽  
Wave Particle Interactions ◽  
Emic Waves

Modeling of pitch angle scattering of ring current protons at interaction with electromagnetic ion cyclotron waves during a nonstorm period was considered very seldom. Therefore it is used correlated observation of enhanced electromagnetic ion cyclotron (EMIC) waves and dynamic evolution of ring current proton flux collected by Cluster satellite near the location L = 4.5 during March 26–27, 2003, a nonstorm period (Dst > –10 nT). Energetic (5–30 keV) proton fluxes are found to drop rapidly (e.g., a half hour) at lower pitch angles, corresponding to intensified EMIC wave activities. As mathematical model is used the non-stationary one-dimensional pitch angle diffusion equation which allows to compute numerically density of phase space or pitch angle distribution of the charged particles in the Earth’s magnetosphere. The model depends on time t, a local pitch angle and several parameters (the mass of a particle, the energy, the McIlwain parameter, the magnetic local time or geomagnetic eastern longitude, the geomagnetic activity index, parameter of the charged particle pitch angle distribution taken for the 90 degrees pitch angle at t = 0, the lifetime due to wave–particle interactions). This model allows numerically to estimate also for different geophysical conditions a lifetime due to wave–particle interactions. It is shown, that EMIC waves can yield decrements in proton flux within 30 minutes, consistent with the observational data. The good consent is received. Comparison of results on full model for the pitch angle range from 0 up to 180 degrees and on the model for the 90 degrees pitch angle is lead. For a perpendicular differential flux of the Earth’s ring current protons very good consent with the maximal relative error approximately 3.23 % is received

Localized heating of the Martian topside ionosphere through the combined effects of magnetic pumping by large scale magnetosonic waves and pitch angle diffusion by whistler waves

2020 ◽  
Author(s):  
Christopher Fowler ◽  
Oleksiy Agapitov ◽  
Shaosui Xu ◽  
David Mitchell ◽  
Laila Andersson ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Large Scale ◽  
Local Heating ◽  
Electron Distribution Function ◽  
Topside Ionosphere ◽  
Particle Interactions ◽  
Whistler Waves ◽  
Compressive Wave ◽  
Superthermal Electron ◽  
Wave Particle Interactions

<p>We present Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of periodic (~ 25 s) large scale (100s km) magnetosonic waves propagating into the Martian dayside upper ionosphere. These waves adiabatically modulate the superthermal electron distribution function, and the induced electron temperature anisotropies drive the generation of observed electromagnetic whistler waves. The localized (in altitude) minimum in the ratio f<sub>pe</sub> / f<sub>ce</sub> provides conditions favorable for the local enhancement of efficient wave-particle interactions, so that the induced whistlers act back on the superthermal electron population to isotropize the plasma through pitch angle scattering. These wave-particle interactions break the adiabaticity of the large scale magnetosonic wave compressions, leading to local heating of the superthermal electrons during compressive wave `troughs'. Further evidence of this heating is observed as the subsequent phase shift between the observed perpendicular-to-parallel superthermal electron temperatures and compressive wave fronts. Such a heating mechanism may be important at other unmagnetized bodies such as Venus and comets.</p>

Collisional broadening of nonlinear resonant wave–particle interactions

2021 ◽  
Vol 87 (6) ◽  
Author(s):  
Peter J. Catto ◽  
Elizabeth A. Tolman
Keyword(s):  
Boundary Layers ◽  
Alpha Particle ◽  
General Procedure ◽  
Nonlinear Effects ◽  
Particle Energy ◽  
Current Drive ◽  
Particle Interactions ◽  
Resonant Wave ◽  
Order Of Magnitude ◽  
Wave Particle Interactions

A general procedure for understanding plasma behaviour when resonant wave–particle interactions are the sole destabilizing and transport mechanism or only heating and/or current drive source is highlighted without recourse to involved numerical or analytical treatments. These phenomena are characterized by transport that appears to be collisionless even though collisions play a central role in narrow collisional boundary layers. The order of magnitude estimates, which include nonlinear effects, are shown to provide expressions in agreement with the principal results of recent toroidal Alfvén eigenmode (TAE), toroidal magnetic field ripple, and heating and current drive treatments. More importantly, the retention of nonlinearities leads to new estimates of the alpha particle energy diffusivity at saturation for TAE modes, and the ripple threshold at which superbanana plateau evaluations of alpha particle transport are modified by nonlinear radial drift effects. In addition, the estimates indicate when quasilinear descriptions for heating and current drive will begin to fail. The phenomenological procedure demonstrates that in magnetic fusion relevant plasmas, narrow collisional boundary layers must be retained for resonant wave–particle interactions as they enhance the role of collisions, and make stochastic particle motion unlikely to be more important than other nonlinear processes.

scholarly journals Particle transport in <sup>3</Sup>He-rich events: wave-particle interactions and particle anisotropy measurements

2002 ◽  
Vol 20 (4) ◽  
pp. 427-444 ◽  
Author(s):  
B. T. Tsurutani ◽  
L. D. Zhang ◽  
G. L. Mason ◽  
G. S. Lakhina ◽  
T. Hada ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Solar Proton ◽  
Energetic Particles ◽  
Proton Event ◽  
Mhd Waves ◽  
Particle Interactions ◽  
Angle Scattering ◽  
Solar Proton Events ◽  
Wave Particle Interactions ◽  
Scattering Rates

Abstract. Energetic particles and MHD waves are studied using simultaneous ISEE-3 data to investigate particle propagation and scattering between the source near the Sun and 1 AU. 3 He-rich events are of particular interest because they are typically low intensity "scatter-free" events. The largest solar proton events are of interest because they have been postulated to generate their own waves through beam instabilities. For 3 He-rich events, simultaneous interplanetary magnetic spectra are measured. The intensity of the interplanetary "fossil" turbulence through which the particles have traversed is found to be at the "quiet" to "intermediate" level of IMF activity. Pitch angle scattering rates and the corresponding particle mean free paths lW - P are calculated using the measured wave intensities, polarizations, and k directions. The values of lW - P are found to be ~ 5 times less than the value of lHe , the latter derived from He intensity and anisotropy time profiles. It is demonstrated by computer simulation that scattering rates through a 90° pitch angle are lower than that of other pitch angles, and that this is a possible explanation for the discrepancy between the lW - P and lHe values. At this time the scattering mechanism(s) is unknown. We suggest a means where a direct comparison between the two l values could be made. Computer simulations indicate that although scattering through 90° is lower, it still occurs. Possibilities are either large pitch angle scattering through resonant interactions, or particle mirroring off of field compression regions. The largest solar proton events are analyzed to investigate the possibilities of local wave generation at 1 AU. In accordance with the results of a previous calculation (Gary et al., 1985) of beam stability, proton beams at 1 AU are found to be marginally stable. No evidence for substantial wave amplitude was found. Locally generated waves, if present, were less than 10-3 nT 2 Hz-1 at the leading proton event edge, where dispersion effects (beaming) are the greatest, and at the point of peak proton flux, where the particle energy flux is the greatest.Key words. Interplanetary physics (energetic particles; MHD waves and turbulence) – Space plasma physics (charged particle motion and acceleration; wave-particle interactions)

Resonant wave-particle interactions modified by intrinsic Alfvénic turbulence

2012 ◽  
Vol 19 (8) ◽  
pp. 082902 ◽  
Author(s):  
C. S. Wu ◽  
C. B. Wang ◽  
D. J. Wu ◽  
K. H. Lee
Keyword(s):  
Particle Interactions ◽  
Resonant Wave ◽  
Wave Particle Interactions
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