A real-time algorithm of spatial inversion for the line- integral signals and its application in HT-7 Tokamak

Abstract

Abstract: A new algorithm is introduced to reconstruct the parameters of plasma from line-integral data. This method is based on the Radon inversion theory. The series expansion and least-square methods are employed to get the Radon inversion of the plasma parameter on the minor cross-section of tokamak. Then the plasma parameter can be given by the Radon inversion formula. This algorithm is introduced to study the asymmetric phenomenon between the positive and negative current plasma of the X-ray emission in HT-7 tokamak.

Key words: Tokamak, Line-integral measurement, Spatial inversion, AC discharge

摘要： 介绍了一种通过线积分测量数据来快速重建等离子体参数的算法。该算法基于Radon反演定理，通过级数展开与最小二乘原理的方法来得到等离子体参数在托卡马克小圆截面上的Radon变换，最后由Radon逆变换公式给出等离子体参数的空间分布。应用这种算法研究了HT-7装置交流放电实验的软X射线在电流正负半周期空间分布的非对称性现象。

关键词: 托卡马克, 线积分测量, 空间反演, 交流放电

CLC Number:

O536

YANG Jian-hua,GAO Xiang,HU Li-qun,WU Zhen-wei. A real-time algorithm of spatial inversion for the line- integral signals and its application in HT-7 Tokamak[J]. NUCLEAR FUSION AND PLASMA PHYSICS, 2010, 30(2): 115-121.

杨建华，高翔，胡立群，吴振伟. HT-7装置线积分信号的快速空间反演方法[J]. 核聚变与等离子体物理, 2010, 30(2): 115-121.

References

[1] Hutchinson I H. Principles of plasma diagnostics [M]. UK: Cambridge University Press, 2002.

[2] Barr W L. Method for computing the radial distribution of emitters in a cylindrical source [J]. J. Opt. Soc. Am., 1962, 52: 885.

[3] Yasu Tomo Y. A new numerical method for asymmetrical Abel inversion [J]. IEEE Trans. on Plasma Science, 1981, PS-9: 18.

[4] 李定, 霍裕平. 用Radon变换处理非圆截面等离子体的测量结果 [J]. 中国物理, 1987, 36: 275.

[5] Nagayama Y. Tomography of m=1 mode structure in tokamak plasma using least-square-fitting method and Fourier-Bessel expansions [J]. J. Appl. Phys., 1987, 62: 2702.

[6] Ruan H L, Wan B N. Dealing with asymmetrical Abel inversion using Fourier-Bessel expansions [J]. Plasma Science & Technology, 2000, 2: 357.

[7] Ruan H, Wan B N, Wu Z W, et al. A new improvement method of Abel inversion [J]. International Journal of Infrared and Millimeter Waves, 2004, 25: 489.

[8] Tian C L, Zhou Y. The application of Barr numerical method to realize Abel inversion [J]. Plasma Science & Technology, 2006, 8: 521.

[9] Ma T P. Study of sawtooth oscillations on the HT-7 tokamak using 2D tomography of soft X-ray signal [J]. Chin. Phys., 2005, 14: 2061.

[10] Ma T P. Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak [J]. Chin. Phys., 2006, 15: 593.

[11] Deans S R. The Radon transform and some of its applications [C]. New York: J. Wiley, 1983, 204-217.

[12] 庄天戈. CT原理与算法 [M]. 上海: 上海交通大学出版社, 1992.

[13] Barrett H H, Swindell W. Radiological imaging: the theory of image formation, detection, and processing, vol 2 [M]. California: Academic Press, 1981.

[14] Kak A C, Slaney M. Principles of computerized tomographic image [M]. USA: IEEE Press, 1988.

[15] 张东平, 张定华, 张丰收, 等. 滤波器对滤波反投影重建图像质量的影响 [J]. 机械设计与制造, 2007, 9: 66.

[16] Gao X.. Particle confinement and transport confinements in ac plasma on the HT-7 superconducting tokamak [J]. Nucl. Fusion, 2008, 48: 035009.

[17] Gao W, Gao X, Wu Z W, et al. Study of impurity behaviour in ac plasma on the HT-7 tokamak [J]. Plasma Phys. Contr. Fusion, 2008, 50: 115003.