Status of Heating and Current Drive Systems Planned for ITER

Abstract

An auxiliary heating power of > 70 MW is envisaged at ITER in order to obtain the plasma temperatures and plasma profiles required to achieve $Q > 10$ for 400 s (inductive ELMy H-mode) and $Q = 5$ for a pulse duration of 3600 s (noninductive discharge), for which a potential upgrade may be necessary. In addition to providing the desired heating, the systems are also expected to drive current, tailor the plasma profile, and control the plasma instabilities. It is difficult to realize such a broad range of functionalities through a single system. As a result, three systems are planned during the first operational phase of ITER, which include the neutral beam (NB), electron cyclotron (EC), and ion cyclotron (IC) systems. While the NB systems are expected to deliver 33 MW of heating power to the plasma and drive current through it by the use of two NB injectors, the IC and the EC systems deliver 20 MW each. IC covers a wide variety of heating and current drive schemes and EC heats the electrons providing local heating and current drive, which can be steered across the plasma cross section. These systems, operating in a hostile radiative environment, become radioactive due to the neutron flux from ITER. Coupled to this are the features of long operating pulse lengths at high powers, reduced maintainability, and increased remote handling requirements. As a result, these devices are challenging to realize compared with their present operational counterparts worldwide. In order to help mitigate the risks involved with the manufacturing, setting up, and operation of these systems at ITER, extensive prototyping and research and development (R&D) activities are underway at various laboratories of the participating domestic agencies (DAs) for each of these systems. This paper provides a brief description of the requirements of each of the three heating systems for the various plasma scenarios foreseen for ITER operation, their functional and technical advantages, the various developments over the period of time, and the present status of the prototype and R&D activities underway to realize these systems and the overall development schedule.