Resonant interaction of tearing modes with energetic-ions resulting in fishbone activities on HL-2A

Abstract

The resonant interaction between energetic-particles and tearing mode is an unresolved physics issue at present. It is found for the first time in tokamaks that an unstable tearing mode with slowly rotating m/n = 2/1 helicity, where m/n represent poloidal/toroidal mode-numbers, interacts with energetic-ions and results in amplitude-bursting/frequency-chirping fishbone-like activities. Nonlinear hybrid kinetic-MHD simulations with M3D-K code prove that the co-passing energetic-ions are responsible for the drive of tearing modes, and the waveparticle resonance condition is satisfied at omega(phi) - 2 omega(theta) - omega = 0, where omega(phi), omega(theta) and omega are the toroidal, poloidal angular frequencies of energetic-ions and the mode frequency respectively. These findings can help the understanding of tearing mode induced energetic-particle loss and particle acceleration during the tearing mode reconnection in laboratory and space plasmas.