April 15-17

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Abstracts

Author: Haijun Ren
Requested Type: Poster
Submitted: 2019-02-19 13:52:13

Co-authors: Wenlong Huang, X. Q. Xu

Contact Info:
University of Science and Technology of China
96 Jinzhai Road
Hefei, Anhui   230026
China

Abstract Text:
The geodesic acoustic mode (GAM) is analytically investigated by taking into account the finite-orbit-width (FOW) resonance effect to the second order and the finite beta effect. The general dispersion relation is derived from the gyro-kinetic equations in the presence of nonzero $delta A_parallel$, the parallel component of the perturbed magnetic vector potential. Transparent and concise expressions for the GAM frequency and Landau damping rate in the presence of the second order FOW effect and finite b effect are first presented. It is clearly shown that the $m = pm 2$ harmonics dominant $delta A_parallel$ and the kinetic expression of $delta A_parallel$ have the same form as the fluid one. For the real frequency, the electromagnetic effect introduces a term on the order of q^2 beta, which is comparable to the second order electrostatic terms, namely, the terms introduced by the second order FOW resonance effect. While for the collisionless damping rate, $delta A_parallel$ does not directly introduce beta-dependent terms, but affects the damping rate via modifying the real frequency. Besides, our analytical result shows good agreement with the numerical examinations.

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