Instability of elliptical vortex cores in electron clouds

Abstract

We investigate the stability of a magnetized electron cloud equilibrium with an elliptical E × B vortex core to the excitation of high frequency electrostatic waves. It is demonstrated that the finite ellipticity of the flow drives the instability of oblique electron plasma oscillations. When the flow ellipticity is small, certain matching conditions between the near rotation frequency of the vortex and the oscillation frequency of the plasma wave are needed. For larger ellipticities, the instability domain is shown to be much broader. Equilibria with elliptic vortex cores are therefore likely to be found with considerable electrostatic noise which will contribute to the transport of the electron fluid across field lines.