Progress with heating and current drive technologies

High power heating and current drive (H&CD) facilities are required to fulf il a number of functions in Next Step tokamaks such as ITER and in power pl ants. The main functions of the ITER H&CD systems are: start-up assist; H-m ode access; heating to ignition; supplementary heating for driven-burn and for controlled plasma shut-down; current drive for extended burn and access to steady-state regimes; performance optimisation, control of plasma insta bilities and making the plasma rotate. This paper reviews recent progress w ith H&CD systems, which has largely come about in response to the needs of ITER [1-3]. We survey how the designs have been influenced by physics requi rements and technical constraints (such as reliable c.w. operation with mod ular integrated port plug designs), and emphasise key outstanding issues. T he four main candidate systems are: electron and ion cyclotron resonance fr equency, lower hybrid, and neutral beam heating. These all have their own p hysics and technology advantages, and disadvantages, and their components a re at various stages of development. (C) 1999 UKAEA Fusion. Published by El sevier Science S.A. All rights reserved.