Fishbone instability was first observed during near-perpendicular neutral beam injection in PDX tokamak [1]. Although a large number of theoretical studies have been made on fishbone instability, little is known about self-consistent nonlinear evolution. Particle-MHD hybrid simulation [2] is carried out to investigate evolution of fishbone instability using parameters similar to the PDX experiment. The goal of our work is to clarify temporal evolution of spatial profile and frequency of fishbone mode, saturation mechanism, and energetic ion transport.
In this paper we focus on linear property of fishbone instability. Frequency, linear growth rate, and spatial profile of fishbone instability are investigated for different energetic ion beta values and beam injection energy.
It is demonstrated that internal kink mode is stabilized for low energetic ion beta value and fishbone mode is destabilized for relatively high energetic ion beta value. It is found that the fishbone mode has a spiral profile in a poloidal plane while the kink mode has a rigid profile.
As for frequency, the fishbone mode rotates with fast ion diamagnetic frequency while the kink mode has no rotation. Growth rate of the fishbone instability has the maximum value when energetic ion precession frequency is close to energetic ion diamagnetic frequency.

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