Oxygen glow discharge experiment to remove deposited layers and to release trapped hydrogen isotopes in HT-7 superconducting tokamak

Oxygen removal with D2-ICR cleanings after oxidation experiment in HT-7

“…A few factors would influence on the precision of the analysis, as discussed in the oxidation experiment [14][15][16][17][18]. (1) The complex distribution of temperature of vessel walls, liners and limiters; the hot area of the wall components facing the plasma is about 12 m 2 with a similar area not facing the plasma.…”

“…The oxidation experiments have been carried out in HT-7 in the last 2 years. It includes oxidation associated with ICR and GDC discharge (O-ICR and O-GDC), and thermal oxidation with neutral oxygen [14][15][16][17]. In order to fast recover high performance plasma after oxidation experiment, it is important to investigate different oxygen removal techniques.…”

Carbon removal in stainless steel wall and graphite sheet by using oxygen glow discharge

“…Tritium inventory in vacuum vessel in ITER is limited below 350 g; for this reason the co-deposited layer has to be removed. The oxygen glow discharging cleaning (He/O 2 -GDC) is proposed for removal of the co-deposited layer by many authors [4,[6][7][8][9]. The He/O 2 -GDC removes co-deposited layer with chemical sputtering by oxygen ions.…”

“…The retained tritium in vacuum vessel is also removed from the co-deposited layer. It is found that the He/O 2 -GDC is effective to remove co-deposited layer by the research conducted at Tokamak [6][7][8][9]. However, in order to apply this He/O 2 -GDC for ITER, further investigations of carbon removal, such as the removal rate and its influence for the first wall material, by the He/O 2 -GDC is needed.…”

Thermo-oxidation to remove re-deposited layers and to release trapped hydrogen isotopes in HT-7 superconducting tokamak

“…The oxidation experiments that have been carried out in the HT-7 superconducting tokamak include oxidation associated with ion cyclotron resonance discharge and glow discharge cleaning (O-ICR and O-GDC) [19,20], and thermo-oxidation with molecular oxygen. The objective of the experiments is to compare the removal rate of hydrogen and carbon for the different oxidation procedures.…”