[P-EM16] Space Plasma Physics: Theory and Simulation

[PEM16-08] A comprehensive model of the electron trapping regions on the resonant/non-resonant wave-particle interactions

*Masahiro Kitahara¹, Yoshizumi Miyoshi¹, Satoko Nakamura¹, Masafumi Shoji¹, Yuto Katoh², Naritoshi Kitamura³ (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Department of Geophysics, Graduate School of Science, Tohoku University, 3.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo)

Keywords:Wave-particle interaction, Cyclotron resonance, non-resonance interaction, Particle acceleration, Pitch angle scattering

Wave-particle interactions play a crucial role in the plasma dynamics such as particle acceleration, pitch angle scattering, wave growth in space plasmas. For quantitative evaluation of the effectiveness of wave-particle interactions, we should estimate the size of a trapping region of charged particles encountering plasma waves. The trapping region in wave-particle interaction is expressed as a set of closed trajectories in the phase space and involves conserved quantities. By applying the method used in Albert et al. (2021) to the two conserved quantities introduced by Berchem and Gendrin (1984), we classified the motion of non-relativistic electrons on the wave-particle interaction and constructed a new model that can express the exact trapping regions in the velocity space. We found that the model includes various models developed in the previous studies, such as the non-resonant interaction model, the single pendulum model of the cyclotron resonance, the two-valley motion model, and the anomalous trapping at low pitch angles. We also found that this new model includes a new trapping region in the velocity space in the direction opposite to the resonance velocity. This unified model predicts that the trapping region of the non-resonant interaction continuously connects with the trapping region of the cyclotron resonance at the low pitch angle region. Although the motion of trapped particles with the velocities that do not match the cyclotron resonance velocity has been classified into the non-resonant interaction conventionally, in this model, that motion can be classified as the resonance trapping in a broad sense that the resonance condition is defined as the temporal-stationary points of the relative phase angles. The exact trapping regions we derived should be applied to the particle data analysis of the high-time-resolution observations and will enable us to obtain more quantitative interpretations of wave-particle interactions through the cyclotron resonance.