HYBRID INDUCTIVE CURRENT DRIVE NONINDUCTIVE CURRENT DRIVE FOR A TOKAMAK REACTOR

A hybrid current drive scheme is investigated for its potential utiliz ation with a tokamak reactor. In this scheme, the toroidal plasma curr ent I-p is maintained steady by the hybrid use of the tokamak transfor mer and non-inductive current drive (NICD). I-p is driven by the induc tive 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 h alf-cycle as in a.c. operation, the NICD power is applied to overcome the fact that the reversed E impedes I-p and to maintain the direction and magnitude of I-p as unchanged. A small amount of NICD power is fo und to be necessary if n is decreased to a low level in this half-cycl e. 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 that in the a.c. scheme.