EVALUATION OF CURRENT DRIVE REQUIREMENTS AND OPERATING CHARACTERISTICS OF A HIGH BOOTSTRAP FRACTION ADVANCED TOKAMAK REACTOR

The reactor potential of some advanced physics operating modes propose d for the TPX physics program [1] are examined. A moderate aspect rati o (A = 4.5 as in TPX), 2 GW reactor (see Table I for parameters) is an alyzed because of its potential for steady-state, noninductive operati on with high bootstrap current fraction. Particle, energy and toroidal current equations are evolved to steady-state conditions using the 1- 1/2-D time-dependent WHIST transport code [2]. The solutions are there fore consistent with particle, energy and current sources and assumed transport models. Fast wave current drive (FWCD) provides the axial se ed current. The bootstrap current typically provides 80-90% of the cur rent, while feedback on the lower hybrid current drive (LHCD) power ma intains the total current. The sensitivity of the plasma power amplifi cation factor, Q = P-fus/P-aux, to variations in the plasma properties is examined. The auxiliary current drive power, P-aux = P-LH + P-FW; bootstrap current fraction; current drive efficiency; and other parame ters are evaluated. The plasma is thermodynamically stable for the ene rgy confinement model assumed (a multiple of ITER89P). The FWCD and LH CD sources provide attractive control possibilities, not only for the current profile, but also for the total fusion power since the gain on the incremental auxiliary power is typically 10-30 in these calculati ons when overall and Q approximate to 30.