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(EXP5/08) Reversed Magnetic Shear Experiment in the HL-1M Tokamak

E. Y. Wang¹⁾, Y. Liu¹⁾, J. Y. Cao¹⁾, J. F. Dong¹⁾, X. T. Ding¹⁾, Z. C. Deng¹⁾, G. C. Guo¹⁾, X. D. Li¹⁾, X. Hua¹⁾, W. Y. Hong¹⁾, J. Rao¹⁾, L. B. Ran¹⁾, W. B. Xu¹⁾, D. M. Xu¹⁾, L. W. Yan¹⁾, L. Yao¹⁾, Y. Zhou¹⁾, N. M. Zhang¹⁾ and HL-1M Team^1)
 
1) Southwestern Institute of Physics, Chengdu, Sichuan 610041, China

Abstract.  An ohmic shear reversed configuration has been obtained in HL-1M by combined control of plasma current rise and supersonic Molecular Beam Injection (MBI). An equilibrium reconstruction code has been applied to the HL-1M database, which stores data from 32 magnetic probes to derive the current density profile and safety q profile. The current density profile derived from the code is found to be hollow in core plasma and q is nonmonotonic. They are characterized by the peaked density profile and hollow electron temperature profiles. The hollow temperature profile leads to a hollow current density profile and reversed magnetic shear. Current profile control by LHCD was conducted in HL-1M. The sawtooth and m=1 mode instabilities were observed to be suppressed by LHCD. The current profile and q profile reconstructed by the equilibrium code show a hollow current profile during LHCD and they are related to the nonmonotonic q profile. In ECRH off-axis experiments the occurrence of the compound sawtooth observed by the soft X-ray diode array implies that the hollow current density profiles were formed.

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