Abstract
An energetic-electron-driven β-induced Alfvén eigenmode (e-BAE) in an HL-2A tokamak experiment (discharge #17461) was studied using a gyrokinetic particle simulation code. Investigations of e-BAEs excited by an initial perturbation, an external antenna, and an energetic-electron pressure gradient were performed, and the measured eigenfrequencies were found to be close to the experimental observations and the theoretical predictions. The damping mechanism is also discussed based on the simulation results. The e-BAE becomes unstable when the driving force of the energetic-electron pressure gradient exceeds the total background damping. Simulations show that the e-BAE propagates along the diamagnetic direction of the energetic electrons and that the most unstable mode number is n∕m = 1∕3; these findings are in good agreement with the experimental observations. The simulation results also show that the mode is radially localized near the rational surface. Both the mode width and growth rate increase as the background plasma density increases. As the density and temperature of the energetic electrons increase, the eigenfrequency increases slightly, and the growth rate increases considerably.
Published Version
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