Effect of limiter recycling on measured poloidal impurity emission profiles in Tore Supra

Poloidal impurity emission profiles measured with the Tore Supra grazing in cidence duochromator exhibit a complex spatial structure during ergodic div ertor operation with an outboard poloidal guard limiter. As previous measur ements with inboard-wall limited plasmas have shown that these profiles giv e important information about the ergodic field structure, so the contribut ion of local neon recycling from the limiter-induced plume has been modeled . This permits a discrimination of edge and core transport effects. The BBQ 3D scrape-off layer code calculates the asymmetric contribution to the emi ssion amd MIST 1D simulation gives the symmetric part. A systematic increas e is observed in the decay rate of neon emission after injection as the erg odic divertor strength is increased. The calculations permit identification of the limiter plume contribution to the profile structure, and, with this identification, the effect of the divertor to enhance impurity efflux can be seen from the decay data. (C) 2001 Published by Elsevier Science B.V.