Self-consistent plasma-neutral modeling in tokamak plasmas with a large-area toroidal belt limiter

Plasma-neutral phenomena in the edge plasma and scrape-off layer of the Tor us Experiment for Technology Oriented Research [G.H. Wolf and the TEXTOR Te am, J. Nucl. Mater. 122&123, 1124 (1984)] with the toroidal belt Advanced L imiter Test (ALT-II) [D.M. Goebel et al;, J. Nucl. Mater. 162-164, 115 (198 9)] are simulated using the code package B2-EIRENE [D. Reiter et al;, Plasm a Phys. Controlled Fusion 33, 1579 (1991)]. Spatially-constant, anomalous r adial transport coefficients (D,V,chi) are used for fitting measured electr on temperature and density profiles. Primary neutral fluxes are determined by plasma fluxes to material surfaces, and D alpha emissions are predicted from them. Comparison of the predicted D alpha emission with measurements i ndicates a critical need, in predictive modeling, for a self-consistent mod el of fluxes to material surfaces that are parallel to the magnetic field. Appropriate factors are calculated for deducing D+ source rates from D alph a emissions measured in various locations, taking into account molecular pr ocesses and spatially varying plasma parameters; values range from 17 to 28 ions/photon. Ion fluxes lost to pumps or the wall must be explicitly re-in troduced as neutral fluxes at the outer boundary. (C) 1999 American Institu te of Physics. [S1070-664X(99)03707-6].