Transport of energetic ions and electrons energy through the vapor shield during a tokamak plasma disruption

Abstract

Summary form only given. Magfire, a 1D time-dependent coupled MHD-radiation transport code, originally used in modelling the vapor shield development under a blackbody radiation source, has been modified to include a charged particle source. The sources used to model a disruption are monoenergetic beams of electrons and/or deuterons with any given incident heat flux and energy/particle. Magfire uses a Lagrangian coordinate system with a finite differencing method of solving the fluid energy and momentum transport equations. It is shown that, for a typical disruption (20 keV/particle, 10 MW/cm/sup 2/), electrons can penetrate the growing vapor shield for tens of microseconds while the ion beam cannot penetrate the vapor shield except at much higher energies. An electron source will eventually (< 100 /spl mu/s) be completely absorbed by the vapor and will give the same f as an equivalent ion heat flux source. Results show that, in fact, all three sources converge (/spl sim/ 100 /spl mu/s) to the same steady-state value of f for any given heat flux.