Demonstration of 300 kA CHI-startup current, coupling to transformer drive and flux savings on NSTX

摘要

Discharges formed by transient coaxial helicity injection (CHI) in the National Spherical Torus Experiment (NSTX) have attained peak currents of 300 kA for the first time. CHI-started discharges are coupled to induction, and ramped up to over 1 MA. Up to an additional 400 kA of toroidal current is produced, compared with discharges with the same inductive drive without CHI. These CHI-inductively coupled discharges demonstrate flux savings over standard NSTX inductive-only discharges, requiring significantly less transformer flux to reach 1 MA of toroidal current, as well as exhibiting higher elongation and lower internal inductance. These results indicate the potential for substantial current generation capability by CHI in NSTX and in future toroidal devices.