Progress in ICRH and Lower Hybrid Launcher Development
Radio frequency methods of heating and non-inductive current drive have become wen established and are likely to be part of any next-step Tokamak programme. This paper reviews the present state of development of antennae for ion cyclotron heating and recent developments to enhance the effectiveness of fast wave current drive systems. The performance achieved by present systems enables the provision of an ICRH system for next step devices within the existing technology limits. The main Lower Hybrid current drive systems are also reviewed. Present operating limits suggest that the design power density at the grill in large multijunction launchers must be somewhat reduced due to peaking of the electric field. The resulting launcher for a next step machine based on present technology is a large and highly complex device. Development of recent proposals such as the rod array or the hyperguide, in parallel with necessary improvements in the current drive efficiency would make Lower Hybrid a more attractive method of non-inductive current drive for next step machines.