Deuterium removal from beryllium co-deposits by simulated strike-point sweeping

Abstract

Beryllium (Be) co-deposition with hydrogen isotopes will probably be the main mechanism of tritium accumulation in ITER. To reduce the use of baking of the first wall and divertor, raising strike-points during a pure deuterium (D) discharge has been proposed to heat the co-deposits directly and enhance tritium desorption. The feasibility of such plasma-induced removal as a potential means of tritium control has been investigated. Be-D co-deposited layers with a thickness of around 3 μm were created at 428–458 K and exposed to D or H plasma at various temperatures (673–873 K) for various times (180–1200 s). The remaining D content was measured by thermal desorption spectroscopy and compared to the control samples. Plasma-induced desorption was found to be efficient in removing significant amounts of D out of the co-deposits, removing 85% of D from the layer after D plasma exposure at 773 K for 1200 s and 84% of D after exposure at 873 K for only 180 s.

Keywords

• Beryllium co-deposits
• Deuterium
• Tritium removal