Numerical simulation of transport in a field-reversed mirror plasma

Abstract

A computer code is described which simulates the evolution of the axisymmetric toroidal region of a field-reversed mirror plasma. The code alternates between a 1-D transport calculation and a 1-D or 2-D equilibrium calculation. Four 1-D transport equations are solved simultaneously for the ion density, electron entropy, ion entropy and toroidal magnetic flux. The transport equations for these adiabatic quantities are independent of the time rate of change of the poloidal magnetic flux. This choice of dependent variables eliminates some of the coupling of the transport and equilibrium calculation. The physical processes which are modeled by the transport calculation are classical transport using Braginskii transport coefficients, Joule heating of the electrons, collisional transfer of energy between ion and electrons, charge exchange loss of ion energy, radiation cooling of electrons due to impurities, heating of ions by neutral beams and enhancement of electron thermal conductivity by a given factor. The equilibrium calculation consists of the solution of the 2-D Grad-Shafranov equation in the r, z grid. Or, if the adiabatic quantities have not changed much, the 1-D flux surface averaged Grad-Shafranov equation is solved.