The characteristics of beta-induced Alfvén eigenmode (BAE) at L-I-H transitions have been investigated in the HL-2A experiments for the first time. It is found that a BAE of fBAE ∼ 13.6 kHz coexists with the limit cycle oscillations of fLCO ∼ 2.6 kHz and both disappear after the I-H transition in the discharges with L-I-H transitions. It is also found that the ambient turbulence is modulated by the radial electric field at the BAE frequency and that the level of density fluctuation gradually drops in L-I-H transitions, but it remains invariant in L-I-L ones. These results suggest a possible correlation between the BAE and the L-I-H transitions. The sudden disappearance of the BAE in L-I and I-H transitions has the similar effect of sawtooth crashes on triggering L-I-H transitions in the HL-2 A tokamak.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics
- Condensed Matter Physics