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(EX/P2-20) Predictive Study on High Performance Modes of Operation in HL-2A

Qingdi Gao1), R.V. Budny2), Fangzhu Li1), Jinhua Zhang1), Hongpeng Qu1)
1) Southwestern Institute of Physics, Chengdu, China
2) Princeton Plasma Physics Laboratory, Princeton University, Princeton, USA

Abstract.  High performance scenarios in the HL-2A tokamak, which will be ready for operation at the end of 2002, are studied by numerical modelling. Through shifting the plasma column outwards, a shaping plasma with significant triangularity is achieved with sufficient room left for the RF antenna. For the out-shifted shaping plasma ripple loss of high energy ions during NBI is analyzed, resulting in that the ripple loss fraction of NBI power for the shaping plasma is not higher than that for the unshifted circular plasma.The time dependent TRANSP code is used to model realistic reversed magnetic shear (RS) operations in HL-2A. In order to sustain the RS operation towards steady-state, off-axis current drive with a lower hybrid wave at 2.45 GHz is used to control the current profile. Due to the off-axis LHCD combined with the effect of bootstrap current and beam driven current a steady-state RS discharge is formed and sustained until the LH power is turned off. The sustainable RS scenario is robust, and we have performed the RS discharge modeling for various different target plasmas. In RS discharges the plasma confinement is enhanced with the development of an internal transport barrier (ITB). In the RS discharges with shaping plasma geometry, a double transport barrier is produceded.

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IAEA 2003