[Table of Contents]

Plasma and Fusion Research

Volume 5, 001 (2010)

Regular Articles

Collisional-Radiative Model for Spectroscopic Diagnostic of Optically Thick Helium Plasma
Keiji SAWADA, Yusuke YAMADA, Takamasa MIYACHIKA, Naomichi EZUMI1), Atsushi IWAMAE2) and Motoshi GOTO3)
Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan
1)
Nagano National College of Technology, 716 Tokuma, Nagano 381-8550, Japan
2)
Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193, Japan
3)
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 7 September 2009 / Accepted 1 November 2009 / Published 25 January 2010)

Abstract

We have included the effect of radiation trapping in a collisional-radiative model of neutral helium atoms developed by Goto [M. Goto, JQSRT 76, 331 (2003)], which is used to determine the electron temperature and density in plasmas from visible emission line intensities of atoms. In addition to the electron temperature and density, photo-excitation events from the ground state 11S to the 21P, 31P, and 41P states per second per one atom are treated as fitting parameters to reproduce the population density obtained by spectroscopic measurement. The model has been applied to an RF plasma at Shinshu University, Japan. The electron temperature and density and the contribution of radiation trapping to the population density of excited states are evaluated.

Keywords

radiation trapping, helium plasma, collisional-radiative model, electron density, electron temperature, metastable state, RF plasma

DOI: 10.1585/pfr.5.001

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References

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This paper may be cited as follows:

Keiji SAWADA, Yusuke YAMADA, Takamasa MIYACHIKA, Naomichi EZUMI, Atsushi IWAMAE and Motoshi GOTO, Plasma Fusion Res. 5, 001 (2010).