中国物理B ›› 2005, Vol. 14 ›› Issue (10): 2061-2067.doi: 10.1088/1009-1963/14/10/023

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Study of sawtooth oscillations on the HT-7 tokamak using 2D tomography of soft x-ray signal

阮怀林1, 马天鹏2, 胡立群2, 万宝年2, 高翔2, 甄香君2, 周立武2, 孙有文2, 陈忠勇2, 林士耀2, 孔伟2   

  1. (1)Institute of Electronic Engineering, Hefei 230037,China; (2)Institute of Plasma Physics, Chinese Academy of Sciences,Hefei 230031, China
  • 收稿日期:2005-03-24 修回日期:2005-06-25 出版日期:2005-10-20 发布日期:2005-10-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10375070 and 10305012).

Study of sawtooth oscillations on the HT-7 tokamak using 2D tomography of soft x-ray signal

Ma Tian-Peng (马天鹏)a, Hu Li-Qun (胡立群)a, Wan Bao-Nian (万宝年)a, Ruan Huai-Lin (阮怀林)b, Gao Xiang (高翔)a, Zhen Xiang-Jun (甄香君)a, Zhou Li-Wu (周立武)a, Sun You-Wen (孙有文)a, Chen Zhong-Yong (陈忠勇)a, Lin Shi-Yao (林士耀)a, Kong Wei (孔伟)a   

  1. a Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China; b Institute of Electronic Engineering, Hefei 230037, China
  • Received:2005-03-24 Revised:2005-06-25 Online:2005-10-20 Published:2005-10-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10375070 and 10305012).

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摘要： It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate two-dimensional (2D) images of sawtooth oscillation on the HT-7 tokamak using the Fourier--Bessel harmonic reconstruction method, and using the singular value ecomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation.Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasi-interchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows:the magnetic surface is made up of the crescent-shaped ``hot core'' and the circular ``cold bubble''. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.

关键词: soft x-ray tomography, sawtooth oscillation, singular value decomposition (SVD)

Abstract: It is the first time so far as we know that two arrays of multi-channel soft x-ray detectors are used to generate two-dimensional (2D) images of sawtooth oscillation on the HT-7 tokamak using the Fourier--Bessel harmonic reconstruction method, and using the singular value ecomposition to analyse the data from soft x-ray cameras. By these two arrays, 2D image reconstruction of soft x-ray emissivity can be obtained without assumption of plasma rigid rotation.Tomographic reconstruction of the m=1 mode structure is obtained during the precursor oscillation of the sawtooth crash. The crescent-shaped mode structure appearing on the contour map of the soft x-ray emissivity is consistent with the quasi-interchange mode. The characteristics of the m=1/n=1 mode structure observed in the soft x-ray tomography are as follows:the magnetic surface is made up of the crescent-shaped ``hot core'' and the circular ``cold bubble''. The structure of the magnetic surface rotates in the direction of the electron diamagnetic drift and the rotation frequency is the oscillation frequency of soft x-ray signals.

Key words: soft x-ray tomography, sawtooth oscillation, singular value decomposition (SVD)

中图分类号:  (Electrostatic waves and oscillations (e.g., ion-acoustic waves))

  • 52.35.Fp
52.55.Fa (Tokamaks, spherical tokamaks) 29.40.-n (Radiation detectors) 52.25.Os (Emission, absorption, and scattering of electromagnetic radiation ?) 52.30.Cv (Magnetohydrodynamics (including electron magnetohydrodynamics))