PLASMA CONTROL REQUIREMENTS AND CONCEPTS FOR ITER

Plasma control requirements for the International Thermonuclear Experi mental Reactor (ITER) are identified, and an overview of proposed ITER plasma control concepts is presented. ITER will operate with a burnin g deuterium-tritium plasma to produce 1.5 GW effusion power for durati ons of 1000 s or more. Key plasma control requirements to achieve thes e objectives encompass (a) plasma scenario and sequencing: plasma init iation, current rampup, divertor formation, auxiliary heating, ignitio n and burn, deignition (fusion power shutdown), and current rampdown a nd termination; (b) plasma magnetics control: plasma current and shape (R-0, a, kappa, delta) versus time, plus control of critical plasma-t o-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 impuri ty content and/or radiated power fraction; core profile control (auxil iary heating and/or current drive), and divertor control (pumping, in- divertor gas and/or impurity injection and magnetic configuration opti mization for divertor performance); and (d) fast plasma shutdown: fusi on power and current shutdown by means of impurity injection. Physics and hardware concepts are presented as to how these plasma control fun ctions 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.