AN INEXACT NEWTON ALGORITHM FOR SOLVING THE TOKAMAK EDGE PLASMA FLUID EQUATIONS ON A MULTIPLY-CONNECTED DOMAIN

Newton's method is combined with a preconditioned conjugate gradient-like algorithm and finite volume discretization to solve the steady-state two-dimensional tokamak edge plasma fluid equations. A numerical evaluation of the Jacobian is employed. Mesh sequencing, pseudo-transient continuation, and adaptive damping are used to increase the radius of convergence. The computations are performed on a multiply-connected curvilinear geometry in a fully coupled manner. The preconditioned conjugate gradient-like algorithm is shown to have a significant storage advantage over the previously used banded Gaussian elimination, while maintaining the excellent convergence characteristics of the overall algorithm. Simulations of a high recycling divertor and a gaseous divertor on the DIII-D tokamak geometry are used to demonstrate algorithm performance. (C) 1995 Academic Press. Inc.