LOSS-CONE DRIVEN ELECTRON-CYCLOTRON MASER.

Abstract

Electron-cyclotron instabilities may be classified in two ways depending on whether the relativistic correction to the gyrofrequency is important (class S) or not (class N), and whether the instability mechanism is of a maser type (class M) or due to bunching (class B). The loss-cone driven SM instability is explored in detail through numerical calculations of the growth rate and the development of a semi-quantitative theory for the maser mechanism. The numerical calculations are for a hot Maxwellian distribution with a hole in pitch angle alpha ; the distribution falls off with pitch angle inside the loss cone alpha greater than alpha //0 ( greater than pi /2) as a power of a sine function of alpha minus alpha //0. The maser emission is possible at all harmonics s equals 1, 2, . . . ( omega approximately equals s OMEGA //e) and occurs just above the relevant harmonic. The maximum growth rate falls off with increasing s.