COMMENTS ON PARTICLE AND ENERGY-BALANCE IN THE EDGE PLASMA OF ALCATORC-MOD

Particle balance is examined in a large set of representative Alcator C-Mod [I. H. Hutchinson et nl., Phys. Plasmas 1, 1511 (1994)] diverted plasmas using measurements of neutral gas pressures and ionization so urce strengths in the main chamber, and parallel plasma flow into the divertor. It is inferred that plasma flow in the scrape-off layer (SOL ) is dominated by transport to the main chamber walls rather than by f low into the divertor. It follows that (i) the effective diffusion coe fficient for anomalous cross-field particle transport in the SOL must rapidly grow with distance from the magnetic separatrix to account for the measured density profiles, (ii) a significant fraction of the pow er from the core plasma can be convected rather than conducted into th e SOL, and (iii) the neutral pressure at the outer midplane is governe d more by cross-field plasma transport than by wall-plasma separation or divertor/limiter geometries. (C) 1998 American Institute of Physics . [S1070-664X(98)01709-1]