Plasma shaping effects on the geodesic acoustic mode in toroidally axisymmetric plasmas

Journal Article · Tue Jul 15 04:00:00 EDT 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2955766· OSTI ID:21269015

Zhe, Gao; Ping, Wang ^[1]; Sanuki, H ^[2]

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1. Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)
2. National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)

The geodesic acoustic mode (GAM) is studied in noncircular, finite aspect ratio, toroidal plasmas with a gyrokinetic theory and a local magnetohydrodynamics equilibrium model. Dependencies of the GAM frequency on finite aspect ratio and elongation are investigated when trapped particle effects are neglected in the large aspect ratio limit. It is found that the GAM frequency sharply decreases with an increasing elongation by dependence of [2/({kappa}{sup 2}+1)]{sup 1/2} and slightly decreases with an increasing inverse aspect ratio by dependence of about 1-3{epsilon}{sup 2}/4, where {kappa} and {epsilon} are the plasma elongation and inverse aspect ratio. The elongation dependence comes from the modification of classical ion polarization balanced by that of curvature drift polarization while the aspect ratio dependence is due to the former in the leading order.

• OSTI ID: 21269015
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 7 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ASPECT RATIO
AXIAL SYMMETRY
ELONGATION
EQUILIBRIUM
IONS
MAGNETOHYDRODYNAMICS
PLASMA
PLASMA CONFINEMENT
POLARIZATION