Sherwood 2015

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approvedsherwood_2015_abstract_fengwang_final.pdf2015-01-19 07:44:45Feng Wang

Fishbone instability and nonlinear dynamics in HL-2A plasmas

Author: Feng Wang
Requested Type: Poster Only
Submitted: 2015-01-19 07:40:45

Co-authors: G.Y. Fu, W. Chen, L.M. Yu

Contact Info:
Princeton Plasma Physics Laboratory
James Forrestal Campus
Princeton, NJ   08543

Abstract Text:
Fishbone mode was first reported in 1983 on PDX[1], and it can be driven unstable by energetic beam ions in tokamaks. This mode is dominated by a large amplitude m/n=1/1 component, and it usually induces significant fast ion losses. It has been widely studied in experiment and theory regarding its fascinating details, especially about nonlinear dynamics. The HL-2A tokamak has reported abundant fishbone phenomena, such as frequency jumps, V-font-style sweeping, run-on fishbone, sawbone and e-fishbone[2]. To understand fishbone linear stability and nonlinear dynamics in realistic tokamak plasmas, the global kinetic-MHD hybrid code M3D-K[3,4] is used in this work. Firstly, a equilibrium with monotonous q profile with q0<1 is analyzed. With different energetic particle parameters, linearly, either sawtooth or fishbone mode can be excited, and nonlinearly, fishbone mode may also lead to a sawtooth crash. Secondly, fishbone instability with different q profiles is studied, especially for low shear q profiles. Since this mode is strongly dependent on both MHD components and kinetic effects, the magnetic shear is a key critical parameter for the mode stability. Lastly, nonlinear simulation results of fishbone are presented, which might be relevant to the V-font-style sweeping observed in the experiment.

[1] M. N. Rosenbluth, et al 1983 Phys. Rev. Lett. 51 1967
[2] W. Chen, et al 2010 Nucl. Fusion 50 084008
[3] W. Park, et al 1999 plasma. Phys. 6 1796
[4] F.Wang, et al 2013 Plasmas.Phys. 20 102506


March 16-18, 2015
The Courant Institute, New York University