The effect of plasma beta on high-n ballooning stability at low magnetic shear

被引:14
作者
Connor, J. W. [1 ,2 ]
Ham, C. J. [1 ]
Hastie, R. J. [1 ]
机构
[1] Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England
[2] Imperial Coll Sci & Technol & Med, London SW7 2BZ, England
关键词
Shafranov shift; plasma pressure; MHD stability; MHD ballooning equation; TOKAMAK; MODES; CONFINEMENT; INSTABILITY; BOUNDARIES; REGION; JT-60U;
D O I
10.1088/0741-3335/58/8/085002
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
An explanation of the observed improvement in H-mode pedestal characteristics with increasing core plasma pressure or poloidal beta, beta(pol), as observed in MAST and JET, is sought in terms of the impact of the Shafranov shift, Delta', on ideal ballooning MHD stability. To illustrate this succinctly, a self-consistent treatment of the low magnetic shear region of the 's - alpha' stability diagram is presented using the large aspect ratio Shafranov equilibrium, but enhancing both alpha and Delta' so that they compete with each other. The method of averaging, valid at low s, is used to simplify the calculation and demonstrates how alpha, Delta', plasma shaping and 'average favourable curvature' all contribute to stability.
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页数:9
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