Charge Excitation of Plasma Motion in a Magnetic Field

Abstract

The wake of a massive point charge traversing a low-density plasma of vanishing ion temperature, in a constant external magnetic field, is investigated by means of linearized Boltzmann theory. The speed of the exciting charge is taken to be less than the root-mean-square thermal speed of the electrons and the electron thermal energy is taken to be much less than the ion energy associated with the ambient flow velocity, that is, the ion flow velocity as seen in a reference frame moving with the external charge. The magnetic field is taken along the direction of motion of the exciting charge. One of the effects of the magnetic field is the production of oscillations of both the charge density and the potential. Over some regions of space the frequency of these oscillations is approximately equal to the ion cyclotron frequency.