Predictive study of high performance scenarios in HL-2A

摘要

High performance scenarios in the HL-2A tokamak are studied by numerical modelling. Through shifting the plasma column outwards, a shaped plasma with significant triangularity is achieved with sufficient room left for the RF antenna. For the out-shifted, shaped plasma, ripple loss of high energy ions during neutral beam injection (NBI) is analysed, and the results show that the ripple loss fraction of NBI power for the shaped plasma is no higher than that for the unshifted circular plasma. The time dependent TRANSP code is used to model realistic reversed magnetic shear (RS) operation in such plasmas. In order to sustain the RS operation towards steady-state, an off-axis current shear (RS) operatin in such plasmas. In order to sustain the RS operation towards steady-state, an off-axis current drive with a lower hybrid wave at 2.45 GHz is used to control the current profile. A steady-state RS discharge is formed and sustained until the LH power is turned off; the plasma confinement is enhanced with the development of an internal transport barrier. In the RS discharges with shaped plasma geometry, a double transport barrier is developed. To understand the underlying physics for the current profile control with LHCD in HL-2A, the LH wave deposition in plasmas with RS is analysed.