Demonstration of 300 kA CHI Startup Current Coupling to Transformer Drive on NSTX

Discharges started by Transient Coaxial Helicity Injection (CHI) in NSTX have attained peak currents up to 300 kA for the first time. When these discharges are coupled to induction, it has produced over 200 kA additional current over inductive-only operation. For the first time, the CHI-produced toroidal current that couples to induction has continued to increase with the energy supplied by the CHI power supply at otherwise similar values of the injector flux. Furthermore, CHI in NSTX has shown to be energetically quite efficient, producing a plasma current of about 10 A/Joule of capacitor bank energy. These results indicate the potential for substantial current generation capability by CHI in NSTX and in future toroidal devices.