Scaling and profiles of heat flux during partial detachment in DIII-D

We examine the scaling of the peak divertor heat flux and total divertor pl ate power in partially detached divertor (PDD) discharges in DIII-D, as a f unction of input power and radiated power. The peak divertor heat flux in t he attached plasma increases linearly with input power, but saturates in th e detached cases. The total divertor plate power remains linear with input power in both the attached and detached plasmas. This is consistent with th e fact that the heat flux peak is reduced from the attached case but other areas receive increased radiant heating from the detached plasma. The diver tor plate radiant heating is linear with input power because the total radi ated power from the entire plasma is a linear function of input power in bo th attached and detached plasma. In the private flux region, radiated heat flux absorbed on the target plate calculated from bolometer data is enough to account for the measured plate heating. Approximately half of the overal l plate heating power in detached plasma is due to absorbed radiation. (C) 1999 Elsevier Science B.V. All rights reserved.