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Observation of Electron Temperature and Density Gradients in Volumetric Recombining Plasma Using ECR Linear Plasma Experimental Device NUMBER

Kota TAKEDA, Atsushi OKAMOTO, Takaaki FUJITA, Yuichi KAWACHI, Minami SUGIMOTO, Muneo KOIKE, Koki SATO, Yuto YAMADA, Kazuhiro TORII

Nagoya University, Nagoya 464-8603, Japan

(Received 23 April 2025 / Accepted 19 May 2025 / Published 25 July 2025)

Abstract

Spatial gradients of electron temperature and density along the magnetic field line are directly measured in helium recombining plasma using the linear plasma device NUMBER. In a specific neutral gas pressure range, a steep temperature gradient is observed, with a scale length shorter than the device length. At higher pressures, the sign of electron density gradient reversed from positive to negative, indicating existence of a spatial density peak. Reconstruction of spatial temperature and density profiles indicates that monotonically decreasing temperature and the spatial peak of density along the magnetic field line.

Copyright (c) 2025 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

detached divertor, volumetric recombining plasma, electrostatic probe, electron temperature, electron density, distribution along the magnetic field line, rollover

DOI: 10.1585/pfr.20.1201038

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References

• [1] H. Tanaka et al., Phys. Plasmas 27, 102505 (2020).
• [2] K. Yoshimura et al., Plasma Fusion Res. 20, 1401015 (2025).
• [3] Y. Nakashima et al., Nucl. Fusion 57, 116033 (2017).
• [4] N. Ezumi et al., Contrib. Plasma Phys. 38, 31 (1998).
• [5] D. Hamada et al., Plasma Fusion Res. 13, 3401044 (2018).
• [6] K. Yagasaki et al., Plasma Fusion Res. 18, 2401082 (2023).
• [7] A. Okamoto et al., Contrib. Plasma Phys. 46, 416 (2006).