Impurity-Seeding Experiments on JET in Preparation for the ITER-Like Wall
A major step towards development of ITER operating regimes will be taken on JET by installation of a beryllium first-wall and tungsten divertor, providing an ITER-Like Wall (ILW). These new materials imply revised, stringent constraints on tolerable loadings, while exclusion of carbon, primarily to lower fuel retention, is expected to reduce its present typically large contribution to radiated power. To address both issues, seeding of main plasma scenarios with extrinsic impurities is being explored. Attention is particularly focused upon moderation of "steady" loads between ELMs, as a potential adjunct to other active ELM control techniques.