Beta-induced Alfvén eigenmode (BAE) during a strong tearing mode activity (termed as m-BAE) has been observed and investigated in HL-2A. BAE excited by energetic electrons (termed as e-BAE) has been identified both in the Ohmic and ECRH plasma. The hard x-ray spectrum detected by cadmium telluride and the non-thermal radiation measured by electron cyclotron emission are used to analyse the behaviour of the energetic electrons. Experimental results show that the e-BAE is related not only to the populations of the energetic electrons, but also their energy distribution. An interesting result about the BAEs modulated by a supersonic molecular beam and gas puffing is presented. In addition, BAEs during a sawtooth cycle are described in this paper. To assess the identification of the e-BAE and m-BAE, the generalized fishbone-like dispersion relation and magnetic-island-induced BAE dispersion relation are solved near marginal stability, respectively. Compared with experimental results, the calculation analysis shows that the observed frequencies are all close to the theoretical results.
Stability of beta-induced Alfvén eigenmodes (BAE) in DIII-D