Design Description for a Coaxial Helicity Injection Plasma Start-Up System for a ST-FNSF

Economics, design simplifications, and design optimizations, may require a Fusion Nuclear Science Facility (FNSF) based on an ST or AT concept to generate the plasma currents required for initial plasma start-up to be produced without reliance on the conventional central solenoid. The method of Transient Coaxial Helicity Injection (CHI) has been successfully used on the HIT-II device and on the thirty times larger in volume Proof-of-Principle NSTX device, to generate over 200 kA of plasma current, and to demonstrate the physics capability of this concept for the generation of substantial amounts of plasma currents in larger devices. The conceptual design of a transient CHI system for a ST-FNSF (B_T = 3 T, R = 1.7 m, A = 1.7, I_p = 10 MA) is described, in which the projected start-up current generation potential is about 2 MA.