Removal of deuterium retention by various helium discharge cleanings under strong magnetic field in EAST superconducting tokamak

Fuel (deuterium) removal by various helium (He) discharge cleanings under strong magnetic field are studied in EAST superconducting tokamak, including deuterium-to-helium changeover by main plasma operation, glow discharge cleaning (GDC), and ion cyclotron wall conditioning (ICWC). The study demonstrates that He-GDC works well in strong magnetic field, but the cleaning is poloidally located near the GDC anodes. Both He-GDC and He-ICWC are effective in removing deuterium under strong magnetic field. Moreover, deuterium-to-helium changeover by main plasma operation is highly effective in rapidly reducing the deuterium from the first wall surface. A comprehensive comparison of the three techniques shows that deuterium-to-helium changeover and He-GDC exhibit higher deuterium removal rate, and the pulse duration and duty cycle of He-ICWC should be optimized to improve the deuterium removal. These studies present a comprehensive investigation on fuel removal techniques in EAST tokamak, providing valuable insights into the optimization of tritium removal strategies for future fusion reactors.