Design and manufacturing of bulk tungsten tiles for WEST outer limiter

Abstract

Limiter objects are facing high loads, even if they are not as close to the plasma as divertor for example. Loads come from plasma interaction during the standard situation (heat loads) and during abnormal situation like disruption (electromagnetic loads, runaway electrons). In WEST, the initial guess was to use CFC tiles with a tungsten coating for the outer bumper limiter. After two campaigns, it appears that the power and quantity of runaway beams had been underestimated, leading to early damages of the coating on significant surfaces. A second attempt for the tiles is to use bulk tungsten. This should ensure a high resistance the runaway beams. The design is validated for the given specifications. The tiles are manufactured in early 2019, and used during the WEST operations later this year. The first observations show a good resistance to the runaway beam, as expected.