ECH and HHFW Start-Up Experiments on the TST-2 Spherical Tokamak

Plasma start-up experiments without using inductive field have been performed on the TST-2 spherical tokamak device. A low power ECH (2.45GHz/4kW) and a medium power High Harmonic Fast Wave (HHFW) (21MHz/up to 50kW) were used. Comparisons of various operational parameters were carried out to find the optimum conditions for the toroidal and the poloidal field strengths, poloidal field configurations, ECH power and HHFW power. Using only ECH, currents up to about 0.4 kA were generated. Current increments by up to 0.4 kA were observed when we apply HHFW to ECH plasmas.