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Development of Helium Electron Cyclotron Wall Conditioning on TCV for the Operation of JT-60SA
https://repo.qst.go.jp/records/54851
https://repo.qst.go.jp/records/54851c8f6822e-1eea-4ad7-87ea-77ea50605ab6
| Item type | 会議発表論文 / Conference Paper(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2018-02-22 | |||||
| タイトル | ||||||
| タイトル | Development of Helium Electron Cyclotron Wall Conditioning on TCV for the Operation of JT-60SA | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_5794 | |||||
| 資源タイプ | conference paper | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Douai, D.
× Douai, D.× Figini, L.× P., Goodman T.× 諫山, 明彦× 福本, 正勝× Sozzi, C.× Garavaglia, S.× Miyata, Yoshiaki× Moro, A.× Ricci, D.× Blanchard, P.× Silva, M.× Theiler, C.× Vartanian, S.× Verhaegh, K.× Coda, S.× 諫山 明彦× 福本 正勝× 宮田 良明 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Wall conditioning will be required in JT-60SA to control fuel and impurity recycling and to improve plasma performance and reproducibility. In addition to glow discharge cleaning, operable only in the absence of toroidal field, electron cyclotron wall conditioning (ECWC) plasmas created with its ECRF launchers are envisioned. ECWC has been successfully operated in helium at the first harmonic in JT-60U, allowing recovering from disruptions. However, in JT-60SA (R = 2:96 m, a = 1.18 m, Bt = 2.25 T), with gyrotrons frequencies f = 110 or 138 GHz, ECWC discharges will have to be operated at the second harmonic of the EC wave. This paper reports on helium ECWC experiments on TCV in support of JT-60SA operation. About forty discharges have been produced in TCV, at a toroidal field Bt = 1.3-1.54 T, with gyrotrons at 82.7 GHz in X2 mode. Hence, the cold ECR layer lies in TCV at R = 0.78-0.92 m, mimicking operation in JT-60SA. Helium pressures ranged between 0.5 and 2 x 10^{-2} Pa and ECRH powers up to 480 kW, using different launchers. Horizontal and vertical poloidal fields with amplitudes typically 0.1 to 2% of Bt have been used, aiming at extending the discharge vertically and radially. Discharge homogeneity was estimated from the electron density radial profile measured with far-infrared interferometry (FIR) and from visible CCD images, while wall coverage was assessed from the ion saturation current measured by the TCV array of wall-mounted Langmuir probes located at the high and low field sides, and at the bottom of the device. Electron densities of 5-15 x 10^{18} /m^2 and temperatures of 20–40 eV have been measured with the TCV FIR and Thomson Scattering systems. Typical edge temperatures were found to be 3 eV at the probes. The efficiency of ECWC was assessed from the amount of released D2 fuel, measured in the exhaust gas using optical Penning gauges connected to the vacuum vessel. About 2-10^{20} D2 molecules could be removed with the forty He-ECWC discharges operated in TCV. Despite this, the initiation of a standard ohmic D2-plasma could not be sustained after conditioning. Thus, demonstration of the ability of ECWC, operated in X2 mode, to recover to normal operation still remains to be done. For this, a larger operational domain will need to be investigated, e.g., higher pressures, different field patterns, and longer ECWC operation will be needed. | |||||
| 書誌情報 |
Proceedings of the 26th IAEA Fusion Energy Conference 発行日 2016-10 |
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