中国物理B ›› 2020, Vol. 29 ›› Issue (9): 95201-095201.doi: 10.1088/1674-1056/aba2e4

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Gaussian process tomography based on Bayesian data analysis for soft x-ray and AXUV diagnostics on EAST

Yan Chao(晁燕), Liqing Xu(徐立清), Liqun Hu(胡立群), Yanmin Duan(段艳敏), Tianbo Wang(王天博), Yi Yuan(原毅), Yongkuan Zhang(张永宽)   

  1. 1 Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 Southwestern Institute for Physics, CNNC, Chengdu 610200, China
  • 收稿日期:2020-05-30 修回日期:2020-07-02 接受日期:2020-07-06 出版日期:2020-09-05 发布日期:2020-09-05
  • 通讯作者: Liqing Xu, Liqun Hu E-mail:lqxu@ipp.ac.cn;lqhu@ipp.ac.cn
  • 基金资助:
    Project supported by the National Magnetic Confinement Fusion Science Program of China (Grant No. 11505226) and the National Natural Science Foundation of China (Grant No. 11975273).

Gaussian process tomography based on Bayesian data analysis for soft x-ray and AXUV diagnostics on EAST

Yan Chao(晁燕)1,2, Liqing Xu(徐立清)1, Liqun Hu(胡立群)1, Yanmin Duan(段艳敏)1, Tianbo Wang(王天博)3, Yi Yuan(原毅)1,2, Yongkuan Zhang(张永宽)1,2   

  1. 1 Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China;
    2 University of Science and Technology of China, Hefei 230026, China;
    3 Southwestern Institute for Physics, CNNC, Chengdu 610200, China
  • Received:2020-05-30 Revised:2020-07-02 Accepted:2020-07-06 Online:2020-09-05 Published:2020-09-05
  • Contact: Liqing Xu, Liqun Hu E-mail:lqxu@ipp.ac.cn;lqhu@ipp.ac.cn
  • Supported by:
    Project supported by the National Magnetic Confinement Fusion Science Program of China (Grant No. 11505226) and the National Natural Science Foundation of China (Grant No. 11975273).

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摘要： This work presents the Gaussian process tomography (GPT) based on Bayesian data analysis and its applications in soft x-ray (SXR) and absolute extreme ultraviolet spectroscopy (AXUV) diagnostics on experimental advanced superconducting tokamak (EAST). This is the first application of the GPT method in the AXUV diagnostic system in fusion devices. It is found that even if only horizontal detector arrays are used to reconstruct the two-dimensional (2D) distribution of SXR and AXUV emissivity fields, the GPT method performs robustly and extremely fast, which enables the GPT method to provide real-time feedback on impurity transport and fast magnetohydrodynamics (MHD) events. By reconstructing SXR emissivity in the poloidal cross section on EAST, an m/n=1/1 internal kink mode has been observed, and the plasma redistribution due to the kink mode is clearly visible in the reconstructions, where m is the poloidal mode number and n is the toroidal mode number. Sawtooth-like internal disruptions extended throughout the entire plasma core and mainly driven by the m/n=2/1 mode have been acquired. During the sawtooth-like internal disruption crash phase, the conversion from an m=2 mode to an m=1 mode is observed. Using the reconstructed AXUV emissivity field we were able to observe the process of impurity accumulated in the plasma core and the mitigation of core impurity due to neon injection in the plasma edge. The data from all other diagnostics involved in the analysis shows that the reconstructions from AXUV measurements are reliable.

关键词: bayesian inference, Gaussian process, tomography, plasma physics

Abstract: This work presents the Gaussian process tomography (GPT) based on Bayesian data analysis and its applications in soft x-ray (SXR) and absolute extreme ultraviolet spectroscopy (AXUV) diagnostics on experimental advanced superconducting tokamak (EAST). This is the first application of the GPT method in the AXUV diagnostic system in fusion devices. It is found that even if only horizontal detector arrays are used to reconstruct the two-dimensional (2D) distribution of SXR and AXUV emissivity fields, the GPT method performs robustly and extremely fast, which enables the GPT method to provide real-time feedback on impurity transport and fast magnetohydrodynamics (MHD) events. By reconstructing SXR emissivity in the poloidal cross section on EAST, an m/n=1/1 internal kink mode has been observed, and the plasma redistribution due to the kink mode is clearly visible in the reconstructions, where m is the poloidal mode number and n is the toroidal mode number. Sawtooth-like internal disruptions extended throughout the entire plasma core and mainly driven by the m/n=2/1 mode have been acquired. During the sawtooth-like internal disruption crash phase, the conversion from an m=2 mode to an m=1 mode is observed. Using the reconstructed AXUV emissivity field we were able to observe the process of impurity accumulated in the plasma core and the mitigation of core impurity due to neon injection in the plasma edge. The data from all other diagnostics involved in the analysis shows that the reconstructions from AXUV measurements are reliable.

Key words: bayesian inference, Gaussian process, tomography, plasma physics

中图分类号:  (Emission, absorption, and scattering of electromagnetic radiation ?)

  • 52.25.Os
52.25.Vy (Impurities in plasmas) 52.35.Py (Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.))