Plasma and Fusion Research

Volume 13, 3405029 (2018)

Regular Articles


Gas Pressure Measurements in Pure and Mixed Gases at Around 1.0 Pa by Using ASDEX Type Fast Ionization Gauge
Kazuya ICHIMURA, Sotaro YAMASHITA1), Yousuke NAKASHIMA1), Masakatsu FUKUMOTO2), Mamoru SHOJI3), Mizuki SAKAMOTO1), Naomichi EZUMI1), Md. Maidul ISLAM1), Md. Shahinul ISLAM1), Takayuki YOKODO1), Guanyi LEE1), Akihiro TERAKADO1), Kunpei NOJIRI1), Tsubasa YOSHIMOTO1) and Hiromasa TAKENO
Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan
1)
Plasma Research Center, University of Tsukuba, Tsukuba 305-8577, Japan
2)
National Institutes for Quantum and Radiological Science and Technology, Naka 311-0193, Japan
3)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 28 December 2017 / Accepted 8 March 2018 / Published 24 April 2018)

Abstract

Sensitivity of the ASDEX type fast ionization gauge (AIG) to several species of gases; hydrogen, nitrogen, noble gases and their mixtures have been investigated. Mixtures of hydrogen-helium and hydrogen-argon with total gas pressure from 0.2 Pa to 1.5 Pa are investigated in order to simulate the environment of divertor regions. It has been found that the observed output current of AIG in mixed gases are larger than the theoretical output current evaluated from the partial pressures and the sensitivities for pure gases. The enhancement of the AIG sensitivity observed in mixed gas conditions suggests that the ionization is enhanced due to the mixing of different gases. A qualitative analysis on the ionization reactions and their cross-sections has indicated that ionization related with metastable atoms of helium or argon is causing the changes in AIG sensitivity.


Keywords

ASDEX gauge, ionization gauge, gas pressure measurement, mixture gas

DOI: 10.1585/pfr.13.3405029


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