Stability of electrostatic modes in a levitated dipole

Abstract

Plasma confined in a magnetic dipole is stabilized by the expansion of the magnetic flux. The stability of low beta electrostatic modes in a magnetic dipole field is examined when the distribution function is to lowest order Maxwellian. It is shown that for sufficiently gentle density and temperature gradients the configuration would be expected to be stable to magnetohydrodynamic interchange, as well as to dissipative trapped ion and collisionless trapped particle modes. These results are applicable to any magnetic configuration for which the curvature drift frequency exceeds the diamagnetic drift frequency.