NEUTRAL PARTICLE AND RADIATION EFFECTS ON PFIRSCH-SCHLUTER FLUXES NEAR THE EDGE

The edge plasma of a tokamak is affected by atomic physics processes a nd can have density and temperature variations along the magnetic fiel d that strongly modify edge transport. A closed system of equations in the Pfirsch-Schluter regime is presented that can be solved for the r adial and poloidal variation of the plasma density, electron and ion t emperatures, and the electrostatic potential in the presence of neutra ls and a poloidally asymmetric energy radiation sink due to inelastic electron collisions. Neutrals have a large diffusivity so their viscos ity and heat flux can become important even when their density is not high, in which case the neutral viscosity alters the electrostatic pot ential at the edge by introducing strong radial variation. The strong parallel gradient in the electron temperature that can arise in the pr esence of a localized radiation sink drives a convective flow of parti cles and heat across the field. This plasma transport mechanism can ba lance the neutral influx and is particularly strong if multifaceted as ymmetric radiation from the edge (MARFE) occurs, since the electron te mperature then varies substantially over the flux surface. (C) 1998 Am erican Institute of Physics. [S1070-664X(98)01211-7].