FOKKER-PLANCK MODELING OF EDGE PLASMA NEAR THE NEUTRALIZER PLATE IN A TOKAMAK

We have modelled the transport of particles and energy through a tokamak SOL near the neutralizer plate. The electron kinetic/ion fluid code FPI and a two-fluid code were employed for this study. Because of the electron time scale, it would take a very long time to reach steady state with the kinetic code. We have therefore developed a hybrid technique, using both codes in alternation, to reach a full equilibrium compatible with electron kinetics. When it is used in the stand-alone mode, the two-fluid code's results are closest to FPI if a heat flux limiter f=0.2 is used. The electron distribution function is very non-Maxwellian near the plate.