Plasma and Fusion Research

Volume 14, 2405029 (2019)

Regular Articles

Analysis on the Sensitivity of the ASDEX Type Ionization Gauge in Mixed Radiator Gases of Divertor Simulators
Kazuya ICHIMURA, Sotaro YAMASHITA1), Yousuke NAKASHIMA1), Masakatsu FUKUMOTO2), Mamoru SHOJI3), Mizuki SAKAMOTO1), Naomichi EZUMI1), Md. Shahinul ISLAM1), Akihiro TERAKADO1), Kunpei NOJIRI1), Tsubasa YOSHIMOTO1), Toshiki HARA1) and Hiromasa TAKENO
Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
1)
Plasma Research Center, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
2)
National Institutes for Quantum and Radiological Science and Technology, 801-1 Mukouyama, Naka, Ibaraki 311-0193, Japan
3)
National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292, Japan
(Received 30 September 2018 / Accepted 8 December 2018 / Published 12 February 2019)

Abstract

The sensitivity of the ASDEX type ionization gauge (AIG) in the mixture of argon and hydrogen gas, which is a candidate of radiator gas in the radiative divertor, is studied. In a small vacuum chamber, the sensitivity of the AIG is calibrated against capacitance-manometers, which have constant sensitivity for all gas species. Increase of the output signal AIG was observed in the mixture of 25% Ar and 75% H2, although the actual sensitivity of the gauge against gas pressure is degraded. In the gas pressure larger than 0.8 Pa, the degradation of the sensitivity will be the main concern of the measurements. The results indicated that the molecular ions produced by the collision between the metastable argon atom and hydrogen molecule is the main cause of the change of the sensitivity. The change of sensitivity is analyzed by varying the collision energy of the electrons and the ionization cross-section of the ArH molecular ion is evaluated.

Keywords

divertor, gas measurement, ionization gauge, mixture gas, asdex gauge

DOI: 10.1585/pfr.14.2405029

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