Hybrid inductive current drive—non-inductive current drive for a tokamak reactor

A hybrid current drive scheme is investigated for its potential utilization with a tokamak reactor. In this scheme, the toroidal plasma current IP is maintained steady by the hybrid use of the tokamak transformer and non-inductive current drive (NICD). IP is driven by the inductive electric field E in the half-cycle of the high density burn phase of tokamak reactor. When the direction of E is reversed in the next half-cycle as in a.c. operation, the NICD power is applied to overcome the fact that the reversed E impedes IP and to maintain the direction and magnitude of IP as unchange. A small amount of NICD power is found to be necessary if n is decreased to a low level in this half-cycle. In this hybrid operation scheme, there are no problems of periodic ionization loss, breakdown and current ramp that is associated with a.c. operation scheme. Also, the requirement for transformer flux swing is found to be much lower than that in the a.c. scheme.