Estimate of the Deposition Profile of Carbon Pellets Using a High-Speed VUV Imaging System in the LHD

Ming, Tingfeng; Ohdachi, S.; Suzuki, Y.

doi:10.1088/1009-0630/15/12/03

Cited by 2 publications

(2 citation statements)

References 15 publications

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“…Soft x-ray tomography (SXT) is an efficient tool for studying the magnetohydrodynamic (MHD) activities. SXT analysis gives vital insight into the mode structures, their poloidal rotation and growth trajectory [1][2][3][4]. SXT is also employed to study the shift in magnetic axis or the Shafranov shift with different plasma and machine parameters, and recovery of the plasma emission profile is commonly studied with soft x-ray tomography [5,6].…”

Section: Introductionmentioning

confidence: 99%

Soft x-ray tomographic reconstruction of Heliotron J plasma for the study of magnetohydrodynamic equilibrium and stability

Purohit¹,

Suzuki²,

Ohdachi³

et al. 2019

Plasma Sci. Technol.

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The preparation for an experimental soft x-ray tomography study on the Heliotron J (H-J) machine is carried out, with the objectives of evaluating the capability of the current soft x-ray tomographic system in terms of the identification of different mode structures and their poloidal rotation, and the axis shift with different plasma and machine parameters, and fixing the physics goals for the experimental study. These preparations were carried out via a simulated soft x-ray data set arising from different plasma conditions, such as magnetic islands, low beta and high beta. Soft x-ray tomography (SXT) is performed by the discrete pixel method including singular value decomposition and Phillips-Tikhonov regularization, to obtain clear and smooth images. The H-J soft x-ray tomography results from simulated soft x-rays for the equilibrium H-J plasma sensed the magnetic axis shift clearly and an estimate was also achieved. Successful reconstruction for mode structure m=1/n=1 was obtained along with the realization of the poloidal rotation of the structure. The reconstruction for the m=2/n=1 mode was not very clear for the current soft x-ray diagnostic design. Effective mode identification was not possible due to the lack of measurements. The SXT from the current soft x-ray diagnostic on H-J, the magnetic axis shift can be estimated and the m= 1/n=1 mode can be studied. Study of higher poloidal modes is difficult with the current design.

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Section: Introductionmentioning

confidence: 99%

Soft x-ray tomographic reconstruction of Heliotron J plasma for the study of magnetohydrodynamic equilibrium and stability

Purohit¹,

Suzuki²,

Ohdachi³

et al. 2019

Plasma Sci. Technol.

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“…Tomographic reconstruction from imaging diagnostics is a widely accepted methodology for transforming the line integrated data into its integrands [1][2][3][4][5], especially for soft X-ray measurements. The line integrated Soft X-ray data (SX) is magnetic free information, and efficiently represents the plasma interior.…”

Section: Introductionmentioning

confidence: 99%

Capability Studies of the Heliotron J Soft X-Ray Tomographic Diagnostic

Purohit

Suzuki

Ohdachi

et al. 2019

Plasma and Fusion Research

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Imaging diagnostics offers magnetic free information for the plasma emissions and able to define plasma shape and position, impurity distribution, and magnetohydrodynamics (MHD) instabilities. The tomographic reconstruction is one of the powerful tools to analyze imaging diagnostic data. Tomography is employed for a wide range of plasma studies prominently for the soft X-ray (SX). SX tomography allows access to spatiotemporal transient phenomena resulting from the magnetohydrodynamics (MHD) activities, which are important for plasma confinement. Heliotron J (H-J) is an L/M = 1/4 helical axis Heliotron with a low magnetic shear configuration and with a bumpy poloidal plasma shape. An attempt for qualitative evaluation of the tomographic reconstruction capabilities for the Heliotron-J device was made. The tomographic reconstructions were made via Phillips -Tikhonov regularizations from the experimental data set at different locations in the time-space. The results suggests that the diagnostic needs to be improved for a high quality of image reconstruction and possible realization of magnetic axis shift, Shafranov Shift.

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Estimate of the Deposition Profile of Carbon Pellets Using a High-Speed VUV Imaging System in the LHD

Cited by 2 publications

References 15 publications

Soft x-ray tomographic reconstruction of Heliotron J plasma for the study of magnetohydrodynamic equilibrium and stability

Soft x-ray tomographic reconstruction of Heliotron J plasma for the study of magnetohydrodynamic equilibrium and stability

Capability Studies of the Heliotron J Soft X-Ray Tomographic Diagnostic

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