Non-inductive current drive scenarios for steady state operation of an ITER HARD option

The requirements for steady-state operation of a high aspect ratio design, (HARD) option for ITER (International Thermonuclear Experimental Reactor) using non-inductive current drive by neutral beam (NB) injection, lower hybrid (LH) slow waves, and fast waves (FWs) have been examined. For the higher field (B_T=7.1 T) and moderate density (<n_e>=1.1×10²⁰ m^-3) in this HARD steady state operating point, NB injection provides the optimal current drive subject to the constraints of minimizing the total input power and achieving a high plasma internal inductance (l_i=0.75, i.e., a peaked current drive profile). An alternative scenario uses FW current drive in the plasma core combined with LH waves in the outer plasma regions in place of the neutral beams, with approximately 30% higher power requirement. Finally, electron cyclotron resonance current drive is used in either scenario to provide localized perturbation of the current profile at the q=2 surface for disruption stabilization