Plasma and Fusion Research

Volume 20, 1201052 (2025)

Rapid Communications

Revisit to Cormack Inversion Using Function Modification Technique for Plasma Tomography

Yuki NISHIMURA¹⁾, Akihide FUJISAWA²⁾, Yoshihiko NAGASHIMA²⁾, Chanho MOON²⁾, Takashi NISHIZAWA²⁾, Taiki KOBAYASHI²⁾, Naohiro KASUYA²⁾, Tatsuya KOBAYASHI^2,3), Akihiro SHIMIZU^2,3), Tokihiko TOKUZAWA^2,3), Takeshi IDO^2,3)

1): Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
2): Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan
3): National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Gifu 509-5202, Japan

(Received 21 August 2025 / Accepted 22 September 2025 / Published 5 December 2025)

Abstract

The Cormack inversion is a well-known procedure for tomography. However, the Fourier-Bessel function expansion could be preferably used for plasma tomography, since plasma images obtained with the Cormack inversion tend to produce a false plasma image in the boundary without regards to its advantage: the direct structural analysis of plasma is possible using a set of line-integrated data. Here we propose an application of function modification technique to revive the advantage of the Cormack inversion and present successful experimental result in a tomography system of a cylindrical plasma.

Keywords

plasma diagnostics, tomography, Cormack inversion, image reconstruction, Fourier-Zernike function

DOI: 10.1585/pfr.20.1201052

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References

[1] Y. Nagayama et al., J. Appl. Phys. 62, 2702 (1987).
[2] A.M. Cormack, J. Appl. Phys. 35, 2908 (1964).
[3] Y. Nishimura et al., Plasma Fusion Res. 19, 1201014 (2024).
[4] A. Fujisawa et al., Plasma Phys. Control. Fusion 58, 025005 (2016).