Low frequency drift instabilities in a dusty plasma

Abstract

Low frequency drift instabilities are investigated in a dusty magnetized plasma with negatively charged grains in which locally there is an electron density gradient which is opposite in sign to a dust density gradient. Frequencies less than the ion gyrofrequency but much larger than the dust gyrofrequency are considered. Two different equilibria are considered that are characterized by ρd≶Lnd, where ρd is the dust gyroradius and Lnd is the dust density scale length. Instabilities analogous to the universal instability and to the lower-hybrid-drift instability (with the lower-hybrid frequency in this case associated with the dust) are investigated. Possible applications to dusty space plasmas such as the spoke regions of Saturn’s B-ring are discussed.