Plasma and Fusion Research

Volume 16, 1201082 (2021)

Rapid Communications

Proposal of Analysis Method for Pattern Recognition of Two-Dimensional Structure of Plasma
Taiki KOBAYASHI, Akihide FUJISAWA1), Yoshihiko NAGASHIMA1), Chanho MOON1), Daiki NISHIMURA, Kotaro YAMASAKI2) and Shigeru INAGAKI1)
Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
1)
Reserch Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
2)
Department of Mechanical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan
(Received 8 April 2021 / Accepted 6 May 2021 / Published 18 June 2021)

Abstract

Two-dimensional measurement becomes active to explore physics of plasma structure and dynamics. The paper proposes a set of new methods using the Fourier-Bessel function series expansion to characterize the two-dimensional images for plasma and illustrates an example of its application to a phenomenon of quasi-periodic oscillations observed with tomography in a linear plasma device PANTA. The analysis provides quantitative relations between the coherent structure and residual random fluctuations of the oscillations. The results suggest that similarity between their spatial patterns should be increased in the phase when both amplitudes become stronger.

Keywords

linear plasma, tomography, nonlinear oscillation, pattern recognition, similarity

DOI: 10.1585/pfr.16.1201082

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