A field-reversal mechanism in a reversed-field pinch

Publisher Website
Google Scholar
Abstract
A field-reversal mechanism in a reversed-field pinch (RFP) is studied through a three-dimensional resistive compressible magnetohydrodynamic (MHD) simulation of the single- and multiple-helicity modes. As the magnetic Reynolds number increases, the m=1 fluctuating magnetic field grows exponentially and extends radially, and then the flow begins to form the vortex structure around the core of the plasma. This radial flow acts such as to push out the toroidal magnetic field. As the dynamo electric field induced by this interaction increases near the core of the plasma, the toroidal magnetic field at the wall decreases toward the negative value and the toroidal magnetic field reverses. As a result, it is found that the field reversal is achieved by the single-helicity evolution of the m=1 mode alone, without the (m=0; n≠0) modes, and the interaction of the radial flow and the toroidal magnetic field is the most dominant source for the dynamo action on the field-reversal process.