Deuterium and impurity contamination of divertor tiles and collector probes of asdex-upgrade

Abstract

The uptake and release of hydrogen isotopes at the plasma-facing components in magnetic, confinement fusion devices affects the working gas recycling, the plasma behaviour and the tritium inventory [1]. This attracts considerable interest in the investigation of hydrogen trapping during plasma exposure. The most intensive plasma material interaction occurs on limiters and divertor plates. Post-mortem analysis of such components gives information on the total amount of hydrogen isotopes retained in the material after plasma exposure. Recent investigations of divertor tiles of ASDEX-UPGRADE have shown that the dominant trapped deuterium amount is contained in the deposited material at the surface [2]. This surface contamination consists mainly of carbon, boron and the hydrogenic isotopes. Movable collector probes have been applied to investigate the hydrogen trapping and impurity deposition under specific plasma conditions. In the present paper results on the impurity and deuterium contamination at the surface of collector samples are presented and compared with corresponding results from the divertor tiles. The collector samples were exposed to the scrape-off plasma of the main chamber (SOL-probe) and to the divertor plasma (DIV-probe)