Energy transfer between various electron populations via resonant
interaction with whistler mode wave

- Artemiy A Luzhkovskiy,
- David R. Shklyar

Artemiy A Luzhkovskiy

Space Research Institute

Corresponding Author:luzartyom@yandex.ru

Author Profile## Abstract

Electron energization in the Earth's radiation belts caused by resonant
interaction with whistler mode waves currently is under intense
investigation. When the waves are excited due to cyclotron instability
in collisionless plasma, i.e., when the energy source for the waves is
the free energy of unstable electron distribution, particle energization
by excited waves is nothing but energy transfer from one group of
electrons to another mediated by the waves. An example of such a process
is considered in which a quasi-monochromatic whistler mode wave packet
with the frequency and the wave normal angle corresponding to the
maximum growth rate is excited at the equator. Since the maximum growth
rate corresponds to parallel propagating wave, only the first cyclotron
resonance particles play a part in this excitation. While propagating
from the equator towards the Earth, the wave normal vector becomes more
and more oblique, and all cyclotron resonances, in particular, Landau
resonance come into play. Wave-particle interaction at Landau resonance
leads to the wave damping and the corresponding particle energization on
the average. Moreover, we show that the mean square variation of
resonant particle energy greatly exceeds the average value, thus, the
energy increase of some particles is much larger than the Landau
resonance particles get from the wave on the average. This means that
the exchange of energy between different groups of particles through a
wave is a more efficient process than the amplification or damping of a
wave due to its resonant interaction with particles.08 Aug 2023Submitted to *ESS Open Archive * 10 Aug 2023Published in *ESS Open Archive *