Non-inductive solenoid-less plasma current startup in NSTX using transient CHI

Solenoid-free Plasma Start-up in NSTX using Transient CHI

Experiments in NSTX have now demonstrated the coupling of toroidal plasmas produced by the technique of Coaxial Helicity Injection (CHI) to inductive sustainment and ramp-up of the toroidal plasma current. In these discharges, the central Ohmic transformer was used to apply an inductive loop voltage to discharges with a toroidal current of about 100 kA created by CHI. The coupled discharges hav...

Solenoid-free Plasma Start-up in HIT-II and NSTX using Transient CHI

Non-inductive startup using localized washer gun plasma sources on the Pegasus Toroidal Experiment*

Non-inductive startup experiments are being conducted on the ultralow-A Pegasus Toroidal Experiment using an array of localized high current density plasma guns for plasma formation and current drive. This DC helicity injection technique has yielded tokamak-like plasmas of Ip/Itf up to 2.3 (IN > 12), far exceeding that achieved by ohmic induction. The guns are located in the lower divertor regi...

Experimental Demonstration of Tokamak Inductive Flux Saving by Transient Coaxial Helicity Injection on NSTX

Discharges initiated by Transient Coaxial Helicity Injection (CHI) in NSTX have attained peak toroidal plasma currents up to 300 kA. When induction from the central solenoid is then applied, these discharges develop up to 300 kA additional current compared to discharges initiated by induction only. CHI initiated discharges in NSTX have achieved 1 MA of plasma current using only 258 mWb of solen...

Simulated flux-rope evolution during non-inductive startup in Pegasus

Magnetic flux ropes produced during non-inductive startup of the Pegasus Toroidal Experiment [Eidietis N W, et al., 2007 J. Fusion Energy 26 43] are simulated with nonlinear magnetohydrodynamic (MHD) and two-fluid plasma models. A single injector is represented by a localized source-density for magnetic helicity and thermal energy. Results show development of a hollow tokamak-like profile from ...