Shaping effects on the geodesic acoustic mode in tokamaks

Nuclear Fushion

article

Zhe Chen¹  Haijun Ren¹ 

[1] CAS Key Laboratory of Geospace Environment and Department of Engineering and Applied Physics, School of Physical Sciences, University of Science and Technology of China

关键词: shaping effects;    geodesic acoustic mode;    triangularity;    tokamak;    magnetic confinement;   

DOI  :  10.1088/1741-4326/acc817

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

The geodesic acoustic mode (GAM) is investigated with gyro-kinetic equations in Miller local equilibrium model for shaped tokamak plasmas with an arbitrary elongationκand a finite triangularityδ . In particular, the effects of triangularity on GAM frequency and damping rate are analyzed both analytically and numerically. The asymptotic analytical and exact numerical results both show that the frequency almost linearly increases with the triangularity but increases relatively more slowly for a negativeδ , which agree well with the TCV observation on the trend. The analytical results clearly claim that the triangularity effect strength is dependent on the inverse aspect ratio epsilonand Shafranov shift gradient Delta^{^{prime}} , while the numerical results indicate that the safety factorqalso has a significant impact on the triangularity effects. In addition, the damping rate increases rapidly with triangularity whenqis not too large and then saturates whenδis above about 0.3.

【 授权许可】

Unknown