Plasma and Fusion Research

Volume 14, 1201066 (2019)

Rapid Communications

Observation of Axial Neutral-Gas Flow Reversal in an ECR Plasma
Emika ABE, Kenichiro TERASAKA, Shinji YOSHIMURA1), Mitsutoshi ARAMAKI2) and Masayoshi Y. TANAKA
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580, Japan
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
College of Industrial Technology, Nihon University, Narashino 275-8575, Japan
(Received 22 January 2019 / Accepted 24 February 2019 / Published 22 March 2019)


Axial neutral gas transport has been experimentally investigated in a partially ionized cylindrical plasma. The high-accuracy laser induced fluorescence spectroscopy is embraced to evaluate the absolute flow velocity of ions and neutral particles, and the axial flow velocity associated with the mass transport parallel to the magnetic field has been measured by changing the filling gas pressure. It has been found that the neutral gas flow is spatially non-uniform, and the axial flow reversal takes place under a certain circumstance. The experimental results indicate that non-uniformity of neutral gas flow field is generated as a consequence of the plasma-neutral coupling and the axial neutral transport plays an important role in the plasma structure formation.


ECR plasma, laser induced fluorescence spectroscopy, neutral gas flow, plasma-neutral coupling, axial flow reversal

DOI: 10.1585/pfr.14.1201066


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