A 3-D Resistive MHD Simulation Analysis of Field Reversal Control in the Reversed Field Pinch

Abstract

A three-dimensional (3-D) resistive MHD simulation code under the compressibility condition has been applied to analysis of the field reversal control in the reversed field pinch (RFP). Simulation results have shown that a loss of the field reversal at the wall leads to flattening of the toroidal field profile, and also to the rapid increase of the fluctuating magnetic energy due to nonlinear tearing modes with m=1. Moreover, the fluctuating magnetic energy spectrum for the m=1 and m=2 modes rapidly broadens toward high and low n, which is caused by the (m=0; n=−1) mode. By deepening the field reversal at the wall, the reversal surface keeps away from the plasma surface, and safety factor becomes a narrow profile. As a result, a rapid growth and saturation of these tearing modes is suppressed by the field reversal control.