Electrostatic waves in an inhomogeneous collisionless plasma

Abstract

Small amplitude electrostatic ion‐cyclotron waves are examined under a variety of conditions, with emphasis on nonuniform density plasmas, and, in particular, on the drift‐cyclotron flute instability. The plasma is assumed collisionless and uniform in temperature. Rather than seeking plasma parameters which yield marginal stability, solutions of the dispersion relations for various parameter values have been obtained in such a way as to discover, for example, the frequencies and wavelengths at which the growth rate is the largest and which therefore are most likely to be seen experimentally. Perpendicular velocity distributions range from Maxwellian to an idealized (monoenergetic) loss cone. Some new features of known modes are discussed. Connections are made between branches of the solutions in various limits and other modes such as the electron drift waves.