THE TOKAMAK PHYSICS EXPERIMENT - TOKAMAK IMPROVEMENT THROUGH ADVANCEDSTEADY-STATE CONTROL

The achievement of a long-pulse ignited discharge with over 1000 MW of fusion power in the International Thermonuclear Experimental Reactor will be an important goal for the next phase of the world magnetic fus ion program. However, improvements in the physics are needed to design a more economically attractive tokamak power reactor than the present data base would support. Advanced, steady state plasma controls are t he key to realizing these improvements. The Tokamak Physics Experiment has a flexible heating and current drive system for profile control; a flexible poloidal field system that supports a strongly shaped doubl e-null poloidal divertor plasma configuration over a wide range of pro files; and a divertor designed for dispersive operation, flexibility, and remote handling. The machine performance in deuterium is sufficien t to produce a reactor-like bootstrap current profile and to confine f ast electrons for localized current profile control. A conducting stru cture, plasma rotation, field error compensation coils, and profile co ntrol are used to provide stable plasma configurations with beta up to twice the Troyon limit and bootstrap current fraction approaching uni ty. The facility will be designed for 1000 s pulses initially to minim ize the influence of initial transients on system behavior, but the pu lse length can be extended through upgrades of external systems if nec essary.