5) Plasma-wall interaction and particles and heat extraction
(p 1 -
- 3 - 4
5 - 6 -
divertor: an original configuration tested by Tore Supra over 10 years.
c) The different configurations
Over a period of 10 years Tore Supra has intensively tested the possibilities of the ergodic
divertor, which was dismantled in 2000 to start the machine up again in the CIEL configuration with an increased
heat extraction capability (incompatibility between the ergodic
divertor and the main component of the CIEL project: the toroidal pumped limiter).
The main results obtained are as follows :
- good control of the ergodic interference
- efficient screening of impurities
- strong capability to radiate
For example, we see here the screening effect of the ergodic
divertor on impurities. Two successive identical argon injections are carried out, symbolised in green, one in limiter configuration, and the other with the ergodic
divertor activated. We measure in blue the time evolution of the argon signal in the
plasma centre. Before injection, the signal is nearly nil, corresponding to traces of argon in the machine. At the moment of injection, the signal soars, then drops, as the argon
diffuses towards the plasma edge and is eliminated bit by bit from the centre. It can be seen that during the ergodic
divertor phase, the same injection results in a much lower level of argon in the centre. This is the screening efficiency of the ergodic
divertor, blocking impurities at the edge.
Analyses are currently being carried out to study the adaptation of an ergodic
divertor to a next generation machine (that we imagine for the moment fitted with an axisymetric
divertor). In the meanwhile, it is the German machine Textor that will take over study of the ergodic
divertor, with the installation of a new device for a new start-up in 2002.