ECR CURRENT DRIVE IN THE AUTORESONANCE REGIME IN CLOSED CONFINEMENT SYSTEMS

The physical principles underlying ECR current drive in the autoresona nce regime are systematically analyzed. The effect of both the nonunif ormity of the system and Coulomb collisions is examined. The OGRAY cod e, which was developed to investigate the processes that occur in the autoresonance regime, is described and is compared with the other code s used to study ECR plasma heating and ECR current drive in tokamaks. Results are presented from calculations of the microwave-beam trajecto ry, the electron distribution function on the magnetic surfaces crosse d by this beam, the spatial distributions of the heating power and of the density of the generated current, and the resulting current drive efficiency. Our analysis shows that the autoresonance regime holds pro mise for use in small tokamaks such as T-10. The question of whether t his regime can be used in large tokamaks requires a separate study.