Electron acceleration by Z-mode waves associated with cyclotron maser instability

Abstract

We demonstrate by a particle simulation that Z-mode waves generated by the cyclotron maser instability can lead to a significant acceleration of energetic electrons. In the particle simulation, the initial electron ring distribution leads to the growth of Z-mode waves, which then accelerate and decelerate the energetic ring electrons. The initial ring distribution evolves into an X-like pattern in momentum space, which can be related to the electron diffusion curves. The peak kinetic energy of accelerated electrons can reach 3 to 6 times the initial kinetic energy. We further show that the acceleration process is related to the "nonlinear resonant trapping" in phase space, and the test-particle calculations indicate that the maximum electron energy gain Δε[max] is proportional to B[0.57]w, where Bw is the wavemagnetic field.