Plasma Control Requirements and Concepts for ITER

Plasma control requirements for the International Thermonuclear Experimental Reactor (ITER) are identified, and an overview of proposed ITER plasma control concepts is presented. ITER will operate with a burning deuterium-tritium plasma to produce 1.5 GW effusion power for durations of 1000 s or more. Key plasma control requirements to achieve these objectives encompass (a) plasma scenario and sequencing: plasma initiation, current rampup, divertor formation, auxiliary heating, ignition and burn, deignition (fusion power shutdown), and current rampdown and termination; (b) plasma magnetics control: plasma current and shape (R-0, a, kappa, delta) versus time, plus control of critical plasma-to-first-wall clearance gaps, including ion-cyclotron coupling gap and divertor magnetic configuration, during the diverted heating/ignition/burn/deignition phase of the plasma scenario; (c) plasma kinetics and divertor control: core plasma density and/or fusion power, core impurity content and/or radiated power fraction; core profile control (auxiliary heating and/or current drive), and divertor control (pumping, in-divertor gas and/or impurity injection and magnetic configuration optimization for divertor performance); and (d) fast plasma shutdown: fusion power and current shutdown by means of impurity injection. Physics and hardware concepts are presented as to how these plasma control functions will be implemented. Diagnostic measurements needed for plasma control are summarized. The relationship of plasma control to machine protection and public safety is also addressed.