Progress with heating and current drive technologies

High power heating and current drive (H&CD) facilities are required to fulfil a number of functions in Next Step tokamaks such as ITER and in power plants. The main functions of the ITER H&CD systems are: start-up assist; H-mode 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 instabilities and making the plasma rotate. This paper reviews recent progress with 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 requirements and technical constraints (such as reliable c.w. operation with modular integrated port plug designs), and emphasise key outstanding issues. The four main candidate systems are: electron and ion cyclotron resonance frequency, lower hybrid, and neutral beam heating. These all have their own physics and technology advantages, and disadvantages, and their components are at various stages of development.