PLASMA-NEUTRAL GAS INTERACTION IN A TOKAMAK DIVERTOR - EFFECTS OF HYDROGEN MOLECULES AND PLASMA RECOMBINATION

We investigate the influence of hydrogen molecules on plasma recombina tion using a collisional-radiative model for multispecies hydrogen pla smas and tokamak detached divertor parameters. The rate constant found for molecular activated recombination of a plasma can be as high as 2 x 10(-10) cm(3)/s, confirming our pervious estimates. We investigate the effects of hydrogen molecules and plasma recombination on self-con sistent plasma-neutral gas interactions in the recycling region of a t okamak divertor. We treat the plasma flow in a fluid approximation ret aining the effects of plasma recombination and employing a Knudsen neu tral transport model for a 'gas box' divertor geometry. For the model of plasma-neutral interactions we employ we find: (a) molecular activa ted recombination is a dominant channel of divertor plasma recombinati on; and (b) plasma recombination is a key element leading to a decreas e in the plasma flux onto the target and substantial plasma pressure d rop which are the main features of detached divertor regimes.