Comparison of O-ICR wall conditionings for limiter configuration in HT-7 and divertor one in EAST

Ion cyclotron resonance discharge-associated oxidation (He/O-ICR) wall conditioning was successfully carried out on full metallic material walls for a divertor configuration in EAST. Within a range of He/O-ICR parameters (5–20 kW, 1.2–7 × 10−2 Pa) in EAST, the highest removal rates (7.8 × 1022 H-atoms/h, 4.2 × 1022 C-atoms/h) were obtained with 20 kW and 7 × 10−2 Pa He/O-ICR. These rates are about 10 times higher than those in HT-7. Oxygen retention rates were lower than HT-7 by a factor of >10. Results of O-ICR cleanings in both EAST and HT-7 showed that power density, working pressure, plasma-facing area and materials, and pumping speed are the main factors influencing the co-deposit removal rates during O-ICR wall conditioning.