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Impact of Nonuniform Spatial Distribution of Ground-State Atoms on He I Line Intensity Ratio Analysis

Shogo OTSUKA¹⁾, Hiroyuki TAKAHASHI¹⁾, Keigo YOSHIMURA²⁾, Ryota NISHIMURA¹⁾, Shigetaka KAGAYA¹⁾, Muto TAKAHASHI¹⁾, Ryota INOUE¹⁾, Daichi KARAHASHI¹⁾, Hiroki MINAMI¹⁾, Tetsutarou OISHI¹⁾

1)

Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan

2)

National Institutes for Quantum Science and Technology, Rokkasho, Aomori 039-3212, Japan

(Received 17 April 2026 / Accepted 13 May 2026 / Published 1 September 2026)

Abstract

This study developed a model to calculate the optical escape factor in consideration of the spatial distribution of ground-state (11S) helium atoms. Based on the improved model, the impact of spatially nonuniform distribution on the helium line intensity ratio (LIR) method was investigated. The LIR method reproduced the input ne and Te values with good agreement when the spatial distribution was considered appropriately, whereas ne and Te evaluated without considering the distribution exhibited considerable deviations. These results suggest that the spatial distribution of the 11S atoms can be a significant source of uncertainty in the helium LIR method.

Copyright (c) 2026 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

helium line intensity ratio method, radiation trapping, escape factor, spatial distribution of ground-state atoms, CR model

DOI: 10.1585/pfr.21.1202042

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References

• [1] T. Fujimoto and J. Quant., Spectrosc. Radiat. Transfer 21, 439 (1979).
• [2] Y. Iida et al., Rev. Sci. Instrum. 81, 10E511 (2010).
• [3] A. Fruchtman, J. Phys. D: Appl. Phys. 50, 473002 (2017).
• [4] S. Kado et al., J. Nucl. Mater. 415, 1174(2011).
• [5] M. Goto, J. Quant. Spectrosc. Radiat. Transfer 76, 331 (2003).
• [6] R.M. Magee et al., Phys. Plasmas 20, 123511 (2013).