Discrete Alfvén eigenmodes in HL-2A tokamak

Abstract

Basing on HL-2A tokamak, applying a magnetohydrodynamic (MHD) simulate codes, we study the characteristics of discrete Alfvén eigenmodes (αTAEs, α is a measure of plasma pressure gradient) in the power deposition region of lower hybrid wave auxiliary heating scheme. We explore the distribution of αTAE upon varied different plasma profiles. Employing gyrokinetic-MHD hybrid simulate codes, we investigate αTAE kinetically excited by energetic particles produced by neutral beam injection. Furthermore, we study physical characteristics of αTAE destabilized by energy particles in the lower hybrid wave power deposition region. In addition, we find that there exist αTAEs in HL-2A tokamak with relatively small α values. Besides, the αTAEs are mainly distributed in the reversal magnetic shear region. There are the abundant αTAEs in the lower hybrid wave power deposition region, where the amount of lower hybrid wave power deposition is greater. Moreover, with different plasma profiles, abundant αTAEs are found in the different region in the directions of the small radius of the HL-2A tokamak. With the increase of the neutral beam injection energy, the multiple branches of αTAEs are developed kinetically into unstable modes, which may potentially affect the plasma confinement of tokamak. tokamak, Alfvén eigenmodes, energetic particles, instabilities