SURFACE EROSION ISSUES AND ANALYSIS FOR DISSIPATIVE DIVERTORS

Erosion/redeposition is examined for the sidewalls of a dissipative di vertor using coupled impurity transport, charge exchange, and sputteri ng codes, applied to plasma solutions for the ITER design. A key issue for this regime is possible runaway self-sputtering, due to the effec t of a low boundary density and nearly parallel field geometry on rede position parameters. Net erosion rates, assuming finite self-sputterin g, vary with wall location, boundary conditions, and plasma solution, and are roughly of the following order. 200-2000 Angstrom/s for beryll ium, 10-100 Angstrom/s for vanadium, and 0.3-3 Angstrom/s for tungsten .