Beat-Wave Resonant Down Scattering of Diocotron and Kelvin Modes

A theory is presented of beat-wave resonant down scattering of two-dimensional diocotron (or Kelvin) modes, in which modes down scatter to lower azimuthal mode number. The phenomenon is a fluid analogue to nonlinear Landau damping. The principal new result is a quantitative prediction of the scattering rate. The predicted rates and scalings are close to those observed in experiments with magnetized electron...