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Plasma density behavior with new graphite limiters in the Hefei Tokamak-7

2005; American Institute of Physics; Volume: 12; Issue: 8 Linguagem: Inglês

10.1063/1.1995627

1527-2419

Muhammad Asif, Xiang Gao, J. Li, G. L. Kuang, Baonian Wan, Y. X. Jie, J. Y. Zhao, X. D. Zhang, Haiqing Liu, Xin Tong, J. Liu, Qian Xu, Jiansheng Hu, Y. Yang, Biao Shen, Jiangyu Mao, Lisha Hu, Ze Wu, Bili Ling,

Particle accelerators and beam dynamics

A new set of actively cooled toroidal double-ring graphite limiters has been developed in the Hefei Tokamak-7 (HT-7) [X. Gao et al., Phys. Plasmas 7, 2933 (2000)] for long pulse operation. The extension of operational region and density behavior with graphite (C) limiters have been studied in this paper. Extended high-density region at the high plasma current low-qa was obtained. The density profile with the C limiter was studied to compare with the previous molybdenum (Mo) limiter. The critical density of multifaceted asymmetric radiation from the edge (MARFE) onset is observed in the region of Zeff1∕2fGW=0.9∼1.2, where fGW=n¯e∕nGW. (Here n¯e is the maximum line average electron density and nGW is the Greenwald density.) Under the same injected power, the critical density of MARFE onset with the new C limiter is much higher than the previous Mo limiter.