Subharmonic autoresonance of the diocotron mode

This paper investigates the excitation and control of the driven [formula omitted] diocotron mode in a pure electron plasma by adiabatic passage through higher order resonances. The excitation takes place when the driving frequency [formula omitted] is swept such that its [formula omitted] harmonic passes through the linear diocotron mode frequency [formula omitted] [formula omitted] [formula omitted] Once past the resonant region, the mode enters the autoresonant regime characterized by persisting phase locking and strong nonlinearities. The transition to autoresonance occurs provided that the driving amplitude exceeds a sharp threshold, which scales as [formula omitted] where [formula omitted] is the driving frequency chirp rate. The theory of these thresholds for [formula omitted] and [formula omitted] is developed and experimental results for [formula omitted] and [formula omitted] are presented.