The nature of the variability of wave particle interactions in the inner magnetosphere and consequences for diffusion models

2021 ◽  
Author(s):  
Clare Watt ◽  
Hayley Allison ◽  
Rhys Thompson ◽  
Sarah Bentley ◽  
Jonathan Rae ◽  
...  
Keyword(s):  
Diffusion Models ◽  
Particle Interactions ◽  
Inner Magnetosphere ◽  
Numerical Diffusion ◽  
Whistler Mode Wave ◽  
Average Diffusion ◽  
In Situ Observations ◽  
Diffusion Rates ◽  
Wave Particle Interactions

<p>It is important to understand the variability of plasma processes across many different timescales in order to successfully model plasma in the inner magnetosphere. In this presentation, we focus on the interplay between the variability cold plasmaspheric plasma, whistler-mode wave activity, and the efficacy of wave-particle interactions in the inner magnetosphere. We use in-situ observations to quantify the amount and timescales of variability in pitch-angle diffusion due to plasmaspheric hiss in Earth’s inner magnetosphere, and suggest reasons for the variability. We then use a stochastic parameterization scheme to investigate the consequences of that variability in a numerical diffusion model. The results from the stochastic parameterization are contrasted with the standard approach of constructing averaged diffusion coefficients. We demonstrate that even when the average diffusion rates are the same, different timescales of variability in the wave-particle interactions lead to different end results in numerical diffusion models. We discuss the implications of our results for the modelling of wave-particle interactions in magnetospheres, and suggest quantifications that are vital for accurate modelling.</p>

scholarly journals The Acceleration of Electrons to High Energies Over the Jovian Polar Cap via Whistler Mode Wave-Particle Interactions

2018 ◽  
Vol 123 (9) ◽  
pp. 7523-7533 ◽  
Author(s):  
S. S. Elliott ◽  
D. A. Gurnett ◽  
W. S. Kurth ◽  
B. H. Mauk ◽  
R. W. Ebert ◽  
...  
Keyword(s):  
Particle Interactions ◽  
Polar Cap ◽  
Whistler Mode ◽  
Mode Wave ◽  
High Energies ◽  
Whistler Mode Wave ◽  
Wave Particle Interactions

Global models of the inner electron radiation belt and slot region investigating the effects of VLF transmitter waves

2020 ◽  
Author(s):  
Johnathan Ross ◽  
Sarah Glauert ◽  
Richard Horne ◽  
Nigel Meredith ◽  
Mark Clilverd
Keyword(s):  
Radiation Belt ◽  
Low Frequency ◽  
Particle Interactions ◽  
Electron Dynamics ◽  
Global Models ◽  
Inner Magnetosphere ◽  
The Earth ◽  
Radiation Belt Electrons ◽  
Wave Particle Interactions ◽  
Earth Orbits

<p>Signals from man-made very low frequency (VLF) transmitters can leak from the Earth-ionosphere wave guide into the inner magnetosphere, where they propagate in the whistler mode and contribute to electron dynamics in the inner radiation belt and slot region through wave-particle interactions. These inner regions of the magnetosphere are becoming increasingly important from a satellite perspective. For instance, the newly populated Medium Earth Orbits pass though the slot region, and satellites launched via electric orbit raising are exposed to the inner belt and slot region for extended periods of time.</p><p>We have calculated diffusion coefficients associated with wave-particle interactions between radiation belt electrons and waves from each of the strongest VLF transmitters using Van Allen Probe observations. These coefficients are included into global models of the radiation belts to assess the importance of the effects of VLF transmitters individually and collectively on electron populations.</p>

scholarly journals Effect of plasma density on diffusion rates due to wave particle interactions with chorus and plasmaspheric hiss: extreme event analysis

2014 ◽  
Vol 32 (8) ◽  
pp. 1059-1071 ◽  
Author(s):  
A. Sicard-Piet ◽  
D. Boscher ◽  
R. B. Horne ◽  
N. P. Meredith ◽  
V. Maget
Keyword(s):  
Electron Density ◽  
Plasma Density ◽  
Radiation Belts ◽  
Cumulative Distribution ◽  
Cumulative Probability ◽  
Particle Interactions ◽  
Energy Diffusion ◽  
Chorus Waves ◽  
Diffusion Rates ◽  
Wave Particle Interactions

Abstract. Wave particle interactions play an important role in controlling the dynamics of the radiation belts. The purpose of this study is to estimate how variations in the plasma density can affect diffusion rates resulting from interactions between chorus waves and plasmaspheric hiss with energetic particles and the resulting evolution of the energetic electron population. We perform a statistical analysis of the electron density derived from the plasma wave experiment on the CRRES satellite for two magnetic local time sectors corresponding to near midnight and near noon. We present the cumulative probability distribution of the electron plasma density for three levels of magnetic activity as measured by Kp. The largest densities are seen near L* = 2.5 while the smallest occur near L* = 6. The broadest distribution, corresponding to the greatest variability, occurs near L* = 4. We calculate diffusion coefficients for plasmaspheric hiss and whistler mode chorus for extreme values of the electron density and estimate the effects on the radiation belts using the Salammbô model. At L* = 4 and L* = 6, in the low density case, using the density from the 5th percentile of the cumulative distribution function, electron energy diffusion by chorus waves is strongest at 2 MeV and increases the flux by up to 3 orders of magnitude over a period of 24 h. In contrast, in the high density case, using the density from the 95th percentile, there is little acceleration at energies above 800 keV at L* = 6, and virtually no acceleration at L* = 4. In this case the strongest energy diffusion occurs at lower energies around 400 keV where the flux at L* = 6 increases 3 orders of magnitude.

Energetic electron precipitation via oblique whistler mode chorus emissions in the outer radiation belt

2021 ◽  
Author(s):  
Yikai Hsieh ◽  
Yoshiharu Omura
Keyword(s):  
Cyclotron Resonance ◽  
Energetic Electron ◽  
Particle Simulation ◽  
Electron Precipitation ◽  
Particle Interactions ◽  
Outer Radiation Belt ◽  
Whistler Mode ◽  
Mode Wave ◽  
Whistler Mode Wave ◽  
Wave Particle Interactions

<p>Whistler mode chorus emissions in the Earth’s magnetosphere cause energetic electron precipitation and the associated pulsating aurora. First-order cyclotron resonance in parallel whistler mode wave-particle interactions is the main mechanism of the precipitation. Not only cyclotron resonance but also Landau resonance and higher-order cyclotron resonances occur in the oblique whistler mode wave-particle interactions. Especially, electrons can be accelerated and scattered to lower equatorial pitch angles rapidly via Landau resonance. We apply test particle simulation and the Green’s function method to check the energetic electron precipitation caused by oblique chorus emissions. We simulate the wave-particle interactions around L=4.5 for electron ranges from 10 keV to a few MeV. We further compare the precipitation fluxes between parallel and oblique chorus emissions. Our simulation result reveals that oblique chorus emissions lead to more electron precipitation than parallel chorus emissions. At kinetic energy E < 100 keV, the electron precipitation ratio (oblique case/parallel case) is about 1.3. At 100 keV < E < 0.5 MeV, the ratio is greater than 2. At E > 0.5 MeV, the ratio is greater than 2 orders. Multiple resonances effect in the oblique whistler mode wave-particle interactions is the reason for the greater precipitation.</p>

Sign in / Sign up

Export Citation Format

Share Document