Current drive experiments in the HIT-II spherical tokamak

The Helicity Injected Torus programme has made progress in understanding re laxation and helicity injection current drive. Helicity conserving MHD acti vity during the inductive (ohmic) current ramp demonstrates the profile fla ttening needed for coaxial helicity injection (CHI). Results from cathode a nd anode central column CHI pulses are consistent with the electron locking model of current drive from a pure n = 1 mode. Finally. lon density CHI, c ompatible with ohmic operation. has been achieved. Some enhancement of CHI discharges with the application of ohmic heating is shown.