Limiter heat load and consequences on impurity source and transport

Power deposition and consequences during short pulse operation t < 2 s, on non-actively cooled limiter (low held side) and large actively cooled inner -mall limiter (high field side) of Tore-Supra as well as long pulse operati on t > 20 s (plasma limited by the inner wall) are reported. Infrared surfa ce temperature measurements, thermocouples and Langmuir probes are used to diagnose the inner wall front face. They are presented for the first time a nd are complemented by measurements of a reciprocating Langmuir probe locat ed at the top of the machine. A diagram of injected energy versus power sho ws how difficult it is to run high power long pulses in steady state condit ions, which is one of the main goals for the next step fusion machine. An u ncontrolled density rise is observed during long pulse operation (P-LHCD < 2.5 MW, time duration > 20 s). It is believed that it is due to recessed el ements heated by plasma or due fast particle losses due to the ripple. The CIEL project will implement in Tore-Supra a set of actively cooled plasma f acing components so that the performance of long pulse, high power shots sh ould be improved. (C) 1999 Elsevier Science B.V. All rights reserved.