Plasma and Fusion Research

Volume 13, 3406070 (2018)

Regular Articles

Spatially Resolved Measurements of Metastable Atom Density and Electric Field Strength in a Microhollow Cathode Helium Plasma by Laser Absorption Spectroscopy
Keisuke UENO, Kenta KAMEBUCHI, Jiro KAKUTANI, Leo MATSUOKA1), Shinichi NAMBA1), Keisuke FUJII, Taiichi SHIKAMA and Masahiro HASUO
Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8540, Japan
1)
Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan
(Received 28 December 2017 / Accepted 10 April 2018 / Published 12 June 2018)

Abstract

We apply laser absorption spectroscopy to direct-current hollow-cathode helium plasma generated in a 0.3-mm-diameter cylindrical hole at gas pressures of 10 - 80 kPa. The measured transitions are 23S-23P and 21P-31D. We evaluate the helium metastable 23S density and gas temperature using the former transition and the 21P atom density and electric field strength from the latter one. The observed lateral distributions of the 23S and 21P atom densities depend on the gas pressure, which results from the sheath length estimated based on the spatial distribution of the evaluated electric field strength.

Keywords

microhollow cathode discharges, laser absorption spectroscopy, helium metastable

DOI: 10.1585/pfr.13.3406070

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