Divertor physics

The recent progress and current status of divertor studies in association with ITER physics R and D are summarized. The detached divertor (and particularity the partially detached divertor) has recently been investigated as a standard operation mode of ITER. Characteristics of detachment phenomena, such as enhanced radiation loss, recombination processes, drops in plasma pressure etc., have been experimentally investigated and discussed. Such detached divertor states and features have been found to be well reproduced by recently developed simulation codes. Despite experimental studies in tokamaks with different divertor shapes, however, it is still unclear to what degree divertor geometry has improve the detached plasma performance. It has been shown that difficulties in particle fueling in ITER can be mitigated by use of a pellet injection scheme from the high magnetic field side. Experimental results and extensive simulations indicate that no serious problems are likely to develop with respect to the helium exhaust. Also discussed are the R and D activities of archiving, the scrape-off-layer (SOL) data-bases and of deriving some empirical laws for the SOL parameters. Finally, the erosion an redeposition characteristics of wall materials are summarized. (author)