中国物理B ›› 2004, Vol. 13 ›› Issue (9): 1500-1509.doi: 10.1088/1009-1963/13/9/024

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Evolution of local ideal helical perturbations in cylindrical plasma

张文禄, 李定   

  1. Department of Modern Physics, University of Science and Technology of China, Hefei 230027, China
  • 收稿日期:2004-03-15 修回日期:2003-12-24 出版日期:2004-06-21 发布日期:2005-06-21
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10175065, 40244006, 40336052).

Evolution of local ideal helical perturbations in cylindrical plasma

Zhang Wen-Lu (张文禄), Li Ding (李定)   

  1. Department of Modern Physics, University of Science and Technology of China, Hefei 230027, China
  • Received:2004-03-15 Revised:2003-12-24 Online:2004-06-21 Published:2005-06-21
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10175065, 40244006, 40336052).

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摘要： The evolution of a local helical perturbation and its stability property for arbitrary magnetic shear configurations are investigated for the case of in cylindrical geometry. An analytic stability criterion has been obtained which predicts that a strong magnetic shear will enhance the instability in the positive shear region but enhance the stability in the negative shear region. The perturbations with the poloidal and toroidal perturbation mode numbers m/n=1/1 is most unstable due to the stabilizing terms increasing with m. For m/n=1/1 local perturbations in the conventional positive magnetic shear (PMS) configurations, a larger q_{min} exhibits a weaker shear in the core and is favourable to the stability, while in the reversed magnetic shear (RMS) configurations, a larger q_0 corresponds to a stronger positive shear in the middle region, which enhances the instability. No instabilities are found for m≥2 local perturbations. The stability for RMS configuration is not better than that for PMS configuration.

关键词: time expanding method, local ideal helical perturbation, cylindrical plasma

Abstract: The evolution of a local helical perturbation and its stability property for arbitrary magnetic shear configurations are investigated for the case of in cylindrical geometry. An analytic stability criterion has been obtained which predicts that a strong magnetic shear will enhance the instability in the positive shear region but enhance the stability in the negative shear region. The perturbations with the poloidal and toroidal perturbation mode numbers m/n=1/1 is most unstable due to the stabilizing terms increasing with m. For m/n=1/1 local perturbations in the conventional positive magnetic shear (PMS) configurations, a larger $q_{\rm min}$ exhibits a weaker shear in the core and is favourable to the stability, while in the reversed magnetic shear (RMS) configurations, a larger $q_0$ corresponds to a stronger positive shear in the middle region, which enhances the instability. No instabilities are found for m≥2 local perturbations. The stability for RMS configuration is not better than that for PMS configuration.

Key words: time expanding method, local ideal helical perturbation, cylindrical plasma

中图分类号:  (Tokamaks, spherical tokamaks)

  • 52.55.Fa
52.65.Vv (Perturbative methods)