Chapter 6: Plasma auxiliary heating and current drive

Heating and current drive systems must fulfil several roles in ITERoperating scenarios: heating through the H-mode transition and to ignition; plasmaburn control; current drive and current profile control in steady state scenarios; andcontrol of MHD instabilities. They must also perform ancillary functions, such asassisting plasma start-up and wall conditioning. It is recognized that no one systemcan satisfy all of these requirements with the degree of flexibility that ITER willrequire. Four heating and current drive systems are therefore under consideration forITER: electron cyclotron waves at a principal frequency of 170GHz; fast wavesoperating in the range 40-70MHz (ion cyclotron waves); lower hybrid waves at5GHz; and neutral beam injection using negative ion beam technology for operation at1MeV energy. It is likely that several of these systems will be employed inparallel. The systems have been chosen on the basis of the maturity of physicsunderstanding and operating experience in current experiments and on the feasibilityof applying the relevant technology to ITER. Here, the fundamental physics describingthe interaction of these heating systems with the plasma is reviewed, the relevantexperimental results in the exploitation of the heating and current drive capabilitiesof each system are discussed, key aspects of their application to ITER are outlined,and the major technological developments required in each area are summarized.