Penalization modeling of a limiter in the Tokamak edge plasma

An original penalization method is applied to model the interaction of magnetically confined plasma with limiter in the frame of a minimal transport model for ionic density and parallel momentum. The limiter is considered as a pure particle sink for the plasma and consequently the density and the momentum are enforced to be zero inside. Comparisons of the numerical results with one-dimensional analytical solutions show a very good agreement. In particular, the penalization scheme followed in this paper tends to ensure an almost sonic plasma condition at the plasma-obstacle interface, Bohm-like criterion, with relatively weak dependence on the target Mach number profile within the obstacle. The new system being solved in a periodic obstacle free domain, an efficient pseudo-spectral algorithm based on a Fast Fourier transform is also proposed, and associated with an exponential filtering of the unphysical oscillations due to Gibbs phenomenon. Finally, the efficiency of the method is illustrated by investigating the flow spreading from the plasma core to the Scrape-Off Layer at the wall in a two-dimensional system with one, then two neighboring limiters. (C) 2009 Elsevier Inc. All rights reserved.