Carbon balance and deuterium inventory from a carbon dominated to a full tungsten ASDEX Upgrade

The evolution of carbon/boron deposition and the deuterium inventory were determined during the transition from a carbon dominated to a full tungsten ASDEX Upgrade. In the carbon dominated machine about 17 g of carbon were deposited at the inner divertor and in remote areas during one standard discharge campaign. Main carbon sources were the ICRH antennae protection limiters in the main chamber. After coating these limiters with tungsten the carbon deposition decreased to 3–5 g. The remaining carbon originated mainly from erosion at the outer divertor strike point. Transition to a full tungsten machine resulted in a further decrease of the carbon deposition to about 1 g. 1.3–1.7 g deuterium was trapped in codeposited carbon/boron layers in the divertor and in remote areas during the carbon dominated campaigns. The deuterium inventory decreased to 0.16–0.24 g in the full tungsten machine.