KINETIC EFFECTS ON PARTICLE AND HEAT FLUXES IN DETACHED PLASMAS

A model of high recycling scrape-off layer plasmas in tokamaks is pres ented where both ion and electron species are described by nonlinear k inetic equations, Coulomb and charged-neutral particle collisions an i ncluded. The ambipolar electric field and electrostatic sheath potenti al are evaluated self-consistently. Two models of fluid neutral transp ort are used to distinguish the neutral density variation for differen t tokamak divertor geometries. These models are incorporated into a co mprehensive three-dimensional (1-D,2 V) hybrid collisional particle-in -cell-Monte Carlo code wt [Contrib. Plasma Phys, 34, 436 (1994)]. This code is used to investigate the effects of neutrals on divertor plasm a detachment phenomena and on parallel heat and particle fluxes in the presence of strong gradients where fluid descriptions break down. Res ults are given for simulations of detached and attached divertor plasm as, and comparisons are made with solutions from a one-dimensional flu id model and with experimental observations. (C) 1996 American Institu te of Physics.