An overview of recent HL-2A experiments

• Published in: Nuclear fusion 2013-10, Vol.53 (10), p.104009-9
• Main Authors: Duan, X.R., Ding, X.T., Dong, J.Q., Yan, L.W., Liu, Yi, Huang, Y., Song, X.M., Zou, X.L., Xu, M., Yang, Q.W., Liu, D.Q., Rao, J., Xuan, W.M., Chen, L.Y., Mao, W.C., Wang, Q.M., Cao, Z., Li, B., Cao, J.Y., Lei, G.J., Zhang, J.H., Li, X.D., Chen, W., Zhao, K.J., Xiao, W.W., Chen, C.Y., Kong, D.F., Isobe, M., Morita, S., Cheng, J., Chen, S.Y., Cui, C.H., Cui, Z.Y., Deng, W., Dong, Y.B., Feng, B.B., Hong, W.Y., Huang, M., Ji, X.Q., Li, G.S., Li, H.J., Li, Qing, Liu, C.H., Peng, J.F., Shi, B.Z., Wang, Y.Q., Yao, L.H., Yao, L.Y., Yu, D.L., Yu, L.M., Yuan, B.S., Zhou, J., Zhou, Y., Zhong, W.L., Tynan, G., Diamond, P., Yu, C.X., Liu, Yong
• Format: Article
• Language: English
• Subjects: Elm; Fluid dynamics; Fluid flow; Heating; Shear flow; Turbulence; Turbulent flow
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/0029-5515/53/10/104009

For the first time supersonic molecular beam injection (SMBI) and cluster jet injection (CJI) were applied to mitigate edge-localized modes (ELMs) in HL-2A successfully. The ELM frequency increased by a factor of 2-3 and the heat flux on the divertor target plates decreased by 50% on average after SMBI or CJI. Energetic particle induced modes were observed in different frequency ranges with high-power electron cyclotron resonance heating (ECRH). The high frequency (200-350 kHz) of the modes with a relatively small amplitude was close to the gap frequency of the toroidicity-induced Alfvén eigenmode. The coexistent multi-mode magnetic structures in the high-temperature and low-collision plasma could affect the plasma transport dramatically. Long-lived saturated ideal magnetohydrodynamic instabilities during strong neutral beam injection heating could be suppressed by high-power ECRH. The absolute rate of nonlinear energy transfer between turbulence and zonal flows was measured and the secondary mode competition between low-frequency (LF) zonal flows (ZFs) and geodesic acoustic modes (GAMs) was identified, which demonstrated that ZFs played an important role in the L-H transition. The spontaneously generated E × B shear flow was identified to be responsible for the generation of a large-scale coherent structure (LSCS), which provided unambiguous experimental evidence for the LSCS generation mechanism. New meso-scale electric potential fluctuations (MSEFs) at frequency f ∼ 10.5 kHz with two components of n = 0 and m/n = 6/2 were also identified in the edge plasmas for the first time. The MSEFs coexisted and interacted with magnetic islands of m/n = 6/2, turbulence and LF ZFs.