Plasma and Fusion Research

Volume 16, 2402090 (2021)

Regular Articles

MHD Equilibrium Reconstruction Using the Visible Light Tomographic Method with Laplacian Eigenfunction
Kosuke SUZUKI, Sadayoshi MURAKAMI, Satoshi OHDACHI1), Hiroshi IDEI2), Kengoh KURODA2), Ryuya IKEZOE2) and Takumi ONCHI2)
Kyoto University, Kyoto 615-8540, Japan
1)
National Institute for Fusion Science, Toki 509-5292, Japan
2)
The Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
(Received 16 November 2020 / Accepted 3 June 2021 / Published 5 July 2021)

Abstract

A tomographic method using tangential visible light is proposed for MHD equilibrium reconstruction via two processes. The first process is a tomographic method to estimate the last-closed-flux-surface (LCFS) in two-dimensional poloidal cross-section using a single tangential camera image. Applying the Laplacian eigenfunction series expansion and L1 regularization, we can reconstruct the LCFS from relatively sparse and noisy observations. The second method is a free-boundary tokamak equilibrium calculation using the TASK/EQU code, in which we use the estimated plasma surface information as the constraints for the equilibrium calculation. As a result, we develop a new method for identifying equilibrium states using visible light information.

Keywords

equilibrium, tomography, series expansion, Laplacian eigenfunction, L1 regularization

DOI: 10.1585/pfr.16.2402090

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