On the challenge of plasma heating with the JET metallic wall

Abstract

The major aspects linked to the use of the JET auxiliary heating systems:\nNBI, ICRF and LHCD, in the new JET ITER-like wall (JET-ILW) are presented. We\nshow that although there were issues related to the operation of each system,\nefficient and safe plasma heating was obtained with room for higher power. For\nthe NBI up to 25.7MW was safely injected; issues that had to be tackled were\nmainly the beam shine-through and beam re-ionisation before its entrance into\nthe plasma. For the ICRF system, 5MW were coupled in L-mode and 4MW in H-mode;\nthe main areas of concern were RF-sheaths related heat loads and impurities\nproduction. For the LH, 2.5 MW were delivered without problems; arcing and\ngeneration of fast electron beams in front of the launcher that can lead to\nhigh heat loads were the keys issues. For each system, an overview will be\ngiven of: the main modifications implemented for safe use, their compatibility\nwith the new metallic wall, the differences in behavior compared with the\nprevious carbon wall, with emphasis on heat loads and impurity content in the\nplasma.\n