Plasma and Fusion Research

Volume 21, 1201046 (2026)

Rapid Communications

Observation of the Plasma Flow Effect on Ion Temperature Measurements using a Retarding Field Analyzer
Hiroyuki TAKAHASHI1), Shigetaka KAGAYA1), Tetsutarou OISHI1), Shinji YOSHIMURA2)
1)
Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
2)
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
(Received 5 April 2026 / Accepted 2 June 2026 / Published 1 September 2026)

Abstract

A retarding field analyzer (RFA) was designed for the ECR plasma device HYPER-I, making ion temperature (Ti) measurements possible for the first time. Using argon plasma, Ti was measured by rotating the RFA relative to the magnetic field lines in 90-degree increments, while maintaining a constant radial position and discharge conditions. Consistently higher Ti was observed when the RFA was exposed to axial and rotational plasma flows, whereas lower values were measured when it was oriented in the downstream directions. Such discrepancies in Ti are expected to remain robust across devices when RFAs are used in plasmas with significant flow.

Keywords

retarding field analyzer, ion temperature, plasma flow, argon, HYPER-I, ECR

DOI: 10.1585/pfr.21.1201046

Full Text

PDF format ([an error occurred while processing this directive]bytes) PDF Download

References

  • [1] S.T. Lai and C. Miller, AIP Advances 10, 095324 (2020).
  • [2] M. Fraunberger et al., Rev. Sci. Instrum. 91, 094503 (2020).
  • [3] D. Gahan et al., Rev. Sci. Instrum. 79, 033502 (2008).
  • [4] H. Takahashi et al., Phys. Plasmas 30, 053506 (2023).
  • [5] R.A. Pitts et al., Rev. Sci. Instrum. 74, 4644 (2003).
  • [6] S. Kagaya et al., Phys. Plasmas 32, 112103 (2025).
  • [7] S. Yoshimura et al., J. Plasma Phys. 81, 345810204 (2015).
  • [8] K. Nagaoka et al., J. Phys. Soc. Jpn., 70, 131 (2001).