Modular bolometric/soft x-ray diagnostic in Sino-UNIted Spherical Tokamak

Yang, Menghua; Wang, Binbin; Tan, Yidong; Gao, Zhe

doi:10.1063/5.0043678

Cited by 3 publications

(1 citation statement)

References 13 publications

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“…The soft x-ray (SXR) diagnostic system has been widely used in magnetic confinement fusion devices to reconstruct the two-dimensional (2D) SXR emission distribution for the investigation of plasma shape [1], magnetohydrodynamic (MHD) activities [2][3][4][5], impurity transport [6,7] and so on. For a toroidally symmetric tokamak plasma, several poloidal SXR arrays at certain toroidal locations are sufficient for tomography [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Development of a toroidal soft x-ray imaging system and application for investigating three-dimensional plasma on J-TEXT

ZHAO 赵,

LI 李,

ZHANG 张

et al. 2024

Plasma Sci. Technol.

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A toroidal soft X-ray imaging (T-SXRI) system has been developed to investigate the three-dimensional (3D) plasma physics on J-TEXT. This T-SXRI system consists of three sets of SXR arrays. Two sets are newly developed and located on the vacuum chamber wall at toroidal position ϕ of 126.4° and 272.6°, respectively, while one set is established previously at ϕ = 65.5°. Each set of SXR arrays consists of 3 arrays viewing the plasma poloidally, and hence can be used separately to obtain the SXR imaging via the tomographic method. The sawtooth precursor oscillations are measured by T-SXRI. The corresponding images of SXR perturbations are successfully reconstructed at three toroidal positions, hence forms a 3D measurement of the sawtooth precursor. The observed 3D structure is consistent with the helical structure of the m/n = 1/1 mode. The experimental observation confirms that the T-SXRI system is capable of observing the 3D structure of the plasma.

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Section: Introductionmentioning

confidence: 99%

Development of a toroidal soft x-ray imaging system and application for investigating three-dimensional plasma on J-TEXT

ZHAO 赵,

LI 李,

ZHANG 张

et al. 2024

Plasma Sci. Technol.

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Compressive sensing-based tomography for Absolute X-ray UltraViolet (AXUV) diagnostics

Yang

Cheng

Wang

et al. 2023

Review of Scientific Instruments

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Absolute x-ray ultraviolet diagnostics ensures 2D coverage of the radiation emission region that enables tomographic reconstruction. However, retrieving the local emissivity via tomography remains a challenge due to its ill-posed nature. Tikhonov regularization with smoothness operation generally performs well but tends to over-smooth regions with steep gradients and local structure in the radiation profile and may introduce artifacts. In this paper, a tomography method based on compressive sensing theory with Tikhonov regularization terms is developed. Experimental results on multiple phantom sets show that the proposed method improves the reconstruction accuracy and quality in regions with steep gradients compared with the Tikhonov regularization method and suppresses the unphysical negative emissivity. The analysis of reconstruction uncertainty shows that the dictionary learning process provides more accurate prior information about steep gradients to improve the quality of reconstructed images, and compressive sensing has the denoising capability to reduce the impact of noise. Finally, the method is validated by data from the Sino-UNIted Spherical Tokamak, showing fewer artifacts and more reliable reconstruction images than the earlier method.

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