Anomalous decay of induced electron currents in field-reversed systems

Induced electron currents are studied in systems which are field-reversed due to ion currents, with no toroidal magnetic field. In such systems, electron flow is induced in the region of closed field lines, with a large velocity shear that can drive a Kelvin-Helmholtz type instability. Analysis of the nonlinear evolution suggests that the instability leads to a rapid dissipation of electron currents. Rough estimates show that the instability is likely to be of importance in field-reversed ion ring and mirror experiments.