Nonlinear Saturation of Cyclotron Maser Instability Associated with Energetic Ring-Beam Electrons

Abstract

We study the cyclotron maser instability (CMI) driven by an energetic ring-beam distribution by a particle simulation to explain possible generation mechanisms of intense radiation phenomena observed in space. The main objective is to understand the nonlinear processes that control saturation of the emission process. Our study reveals new issues that have been overlooked in past literature. It is found that electrostatic wave modes excited by the electron beam instability compete with the electromagnetic waves excited by the CMI. Nonlinear effects of these electrostatic modes tend to redistribute the energy of the energetic electrons and make the physics more complicated. The CMI can be much less effective in a realistic case than it is anticipated theoretically.

Loss cone‐driven cyclotron maser instability

“…The essential physical explanation for the terrestrial (or auroral) kilometric radiation (AKR for short) was provided by Wu and Lee [] in terms of the maser instability mechanism. Since then, many researchers devoted their efforts on the theoretical investigation of the cyclotron maser instability [ Lee and Wu , ; Hewitt et al , ; Melrose et al , ] as well as on numerical simulations thereof [ Pritchett , , , ; Winglee and Pritchett , ; Pritchett and Winglee , ; Pritchett et al , ; Lee et al , ; Speirs et al , ]. As a result of these efforts, many details associated with the cyclotron maser instability are well known (see, e.g., the recent review by Treumann []).…”

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

“…Wu and Lee 1 and Lee and Wu 2 discovered the importance of relativistic effect on the resonance condition for the generation of X-mode and O-mode waves. Wagner et al, 3 Pritchett et al, 4 and Lee et al 5 simulated CMI based on various velocity distributions with population inversion.…”

“…In the previous literature, the generation of X-and O-mode waves was often discussed. [1][2][3][4][5][6][7] The two wave modes are important because they can be directly amplified and propagate into field-free space. The Z mode needs mode-conversion to generate waves propagating into field-free space.…”

“…However, the electron acceleration by electromagnetic whistler-mode waves has been widely studied recently. 9 In our previous simulation study on ring-beam CMI, 5 we focused on the generation of various wave modes. In this paper, we examine the electron acceleration by carrying out a series of particle simulations with an initial energetic electron ring distribution in the presence of a dense background plasma.…”

A 2D simulation study of Langmuir, whistler, and cyclotron maser instabilities induced by an electron ring-beam distribution

“…Many literatures on the ring-beam CMI were published. [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] Applications to various types of solar radio bursts and to radiations of astrophysical shocks were also studied. [44][45][46][47][48][49][50] It is believed that a ring-beam distribution can provide an effective radiation source for radio emissions.…”