Solenoid-free Plasma Startup in NSTX using Coaxial Helicity Injection

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...

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...

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

× B Plasma Rotation and n = 1 Oscillation Observed in the NSTX - CHI Experiments

In the National Spherical Torus Experiment (NSTX), a peak plasma current up to 390 kA has been successfully generated by the Coaxial Helicity Injection (CHI) current drive method. The plasma rotation (∼ 20 km/s) driven in the E × B toroidal direction by CHI has been clearly identified by an ion Doppler spectroscopic measurement. The n = 1 mode has been also observed to rotate in the same direct...

Study of Magnetic Helicity Injection Via Plasma Imaging Using a High-Speed Digital Camera

The evolution of a plasma generated by a novel planar coaxial gun is photographed using a state-of-the-art digital camera, which captures eight timeresolved images per discharge. This experiment is designed to study the fundamental physics of magnetic helicity injection, which is an important issue in fusion plasma confinement as well as solar and astrophysical phenomena such as coronal mass ej...