Simulations of MHD Dynamo With and Without the Reversal Surface

Fluctuations in the Reversed Field Pinch (RFP) are dominated by Fourier mode numbers m=0 and m=1. The velocity and magnetic fluctuations drive a dynamo which redistributes current in the plasma. In experiments, m=0 modes and dynamo due to m=1 modes are highly dependent on the existence of the reversal surface in the plasma. We investigate the effects of reversal surface on magnetic and velocity fluctuations using a magnetohydrodynamic simulation to model the plasma with and without a reversal surface. We find that while m=0 modes are suppressed through the removal of the reversal surface, magnetic m=1 amplitudes are not affected. Velocity fluctuations for both modes decrease with the reversal surface removed. Work funded by USDOE.