Hydrogen retention in mixed materials

The deuterium inventory in mixed-material surface layers formed during beryllium-containing plasma bombardment of graphite surfaces is investigated. The beryllium-containing plasma simulates the erosion of first wall material into the ITER SOL plasma and its subsequent flow towards the carbon divertor plates. The experiments are designed to quantify the behavior of plasma-created mixed Be/C and Be/W surfaces. Developing an understanding of the mixed-material surface behavior is crucial to accurately predicting the tritium accumulation rate within the ITER vacuum vessel. A new periodic heat pulse deposition system is also installed on PISCES-B to simulate the transient temperature excursions of surfaces expected to occur in the ITER divertor during ELMs and other off-normal events. These periodically applied heat pulses allow us to study the effects of transient power loading on the deuterium content of mixed-material surfaces that are created during the experiments. (author)