Determination of best operation parameters of electron cyclotron wall conditioning in KSTAR. (October 2022)

• Record Type: Journal Article
• Authors: Nakano, T.; Douai, D.; Vartanian, S.; Fukumoto, M.; Son, S.H.; Jang, J.H.; Jeong, W.I.; Kim, J.; Hong, S-H.; Lee, H.H.
• Is Part Of: Nuclear materials and energy. Volume 33(2022)
• Publication Date: 2022-10
• Subjects: Wall conditioning -- Electron cyclotron wave -- Second harmonics -- Outgas; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2022.101275
• Languages: English
• ISSNs: 2352-1791

Abstract

Abstract: Dependence of EC injection power (0.6 and 1.4 MW), EC injection width (0.1–1.0 s) and prefilled He pressure ( 2 . 8 × 1 0 − 5 ∼ 2 . 2 × 1 0 − 3 mbar) on D 2 outgas efficiency is investigated at a toroidal field of 2.4 T in a poloidal trapped particle configuration with an EC wave frequency of 140 GHz (X-mode) and a second harmonic resonance layer near the machine center (1.73 m). With increasing EC injection power, D 2 outgas increases clearly. The dependence of the EC power injection is the most pronounced between the scanned parameters. It is found that an optimum prefilled He pressure for D 2 outgas exists under the condition of a constant EC injection power. It is observed that both high EC injection power and the optimum prefilled He pressure enhance the ion flux to the center stack, suggesting that the D 2 outgas originates from the center stack. Highlights: Parameter scan (prefilled He pressure, EC pulse width, EC power) was performed to determine best ECWC parameters in KSTAR. Within this experiment. In terms of D 2 removal efficiency, optimum He pressure existed, higher EC injection power was better but EC injection length was less effective. It was suggested that D 2 outgassing originated from the center stack. The reason why ECWC at highest He pressure with very small D 2 outgassing resulted in successful burn-through was still unclear.