SIMPLE THEORY OF A NONLINEAR DIOCOTRON MODE

A simple perturbation theory of the frequencies and density distortions of the l = 1 diocotron mode on pure electron plasma columns is presented. This mode is the dynamical state of an off-axis electron column which is orbiting around the containment axis at the E X B drift velocity. The theory predicts shifts in the orbit frequency ind quadrupole distortions of the plasma sur-face, both varying as the offset squared, in good agreement with experiments. The results also apply to a two-dimensional vortex patch in an inviscid fluid with circular boundaries.