Destabilization of the m = 1 diocotron mode in non-neutral plasmas
The theory for a Penning-Malmberg trap predicts m = 1 diocotron stability. However, experiments with hollow profiles show robust exponential growth. We propose a new mechanism of destabilization of this mode, involving parallel compression due to end curvature. The results are in good agreement with the experiments. The resulting modified drift-Poisson equations are analogous to the geophysical shallow water equations, and conservation of line integrated density corresponds to that of potential vorticity. This analogy predicts Rossby waves in non-neutral plasmas and an m = 1 instability in fluids.
Finn
JM
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
del-Castillo-Negrete
D
Barnes
DC