Ion Cyclotron Wall Conditioning (ICWC) on KSTAR

Ion Cyclotron Wall Conditioning (ICWC) has been performed in KSTAR. Fuel retention and removal, impurity removal have been investigated in a dedicated session. By varying pressure (mixture rate) and duty cycle, parameter study has been done. An average hydrogen retention rate of ~2 × 10²⁰ H/sec is measured. The ratio of H_implanted/D^pumped is found to be ~5-15 depending on the operation conditions. Other impurity removal rate is of the order of ~10¹⁶-10¹⁷ molecules/sec. It is shown that inter-shot ICWC is a powerful tool for superconducting tokamaks like KSTAR and ITER.