The effect of beta-induced Alfvén eigenmode on L–I–H transitions in the HL-2A tokamak. (23rd June 2015)

• Record Type: Journal Article
• Authors: Yan, L.W.; Cheng, J.; Dong, J.Q.; Itoh, K.; Zhao, K.J.; Huang, Z.H.; Ji, X.Q.; Yu, D.L.; Nie, L.; Jiang, M.; Liu, C.H.; Song, X.M.; Yuan, B.S.; Liu, Yi; Yang, Q.W.; Ding, X.T.; Itoh, S.-I.; Duan, X.R.; Liu, Y.
• Other Names: collab.
• Is Part Of: Nuclear fusion. Volume 55:Number 7(2015:Jul.)
• Publication Date: 2015-06-23
• Subjects: beta-induced Alfvén eigenmode -- L–I–H transition -- limit cycle oscillations -- electrostatic fluctuation -- magnetic perturbation -- Langmuir probe array -- bicoherence; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/0029-5515/55/7/073026
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: 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 f BAE ∼ 13.6 kHz coexists with the limit cycle oscillations of f LCO ∼ 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.