Plasma and Fusion Research
Volume 13, 3405029 (2018)
Regular Articles
- 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
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
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