Heavy Ion Acceleration by Double-cyclotron Absorption: Some Analytic Approximations

Abstract

Possible to accelerate heavy ions in a magnetised plasma via a process where an ion simultaneously absorbs two gyromagnetic waves whose frequencies sum to the ion gyrofrequency. Analytic approximations to the probability of such double-cyclotron absorption are derived. A particularly simple approximation is presented for the special case where the waves all have frequencies very close to half the ion gyrofrequency. The rate of perpendicular acceleration of the ions due to double-cyclotron absorption is considered, and a simple analytic expression is derived for the case here the waves have the quasimonochromatic distribution mentioned above. One possible application of these proximatio.ns is to investigate the proposal that perpendicular acceleration of oxygen (0+) ions in the Earth's magnetosphere, due to double-cyclotron absorption, may give rise to O+-conic distributions