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New Method to Evaluate Negative-Ion Density Using Conventional Langmuir Probe

Engrhyt RATTANAWONGNARA¹⁾, Masaki OSAKABE^1,2), Shingo MASAKI¹⁾, Katsuyoshi TSUMORI^1,2), Haruhisa NAKANO^2,3), Kenichi NAGAOKA^2,3), Katsunori IKEDA²⁾ and Yasuhiko TAKEIRI²⁾

1)

The Graduate University for Advanced Studies (SOKENDAI), 322-6 Oroshi, Toki, Gifu 509-5292, Japan

2)

National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki, Gifu 509-5292, Japan

3)

Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601, Japan

(Received 10 December 2022 / Accepted 14 February 2023 / Published 5 April 2023)

Abstract

A new experimental method using a Langmuir probe to measure negative-ion density is introduced in an area that cannot use lasers, such as the extraction hole. An electron reduction Langmuir probe model is established to distinguish negative ions from electron density. A comparison between density measured by the Langmuir probe with the electron reduction model and a photo-detachment Langmuir probe is performed to verify the use of the newly developed model.

Copyright (c) 2023 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

negative ion, negative-ion source, electronegative plasma, N-NBI, Langmuir probe

DOI: 10.1585/pfr.18.1401020

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