Study of Plasma MHD Equilibrium in HL-2A Tokamak

Abstract

EFIT(Equi1ibrium Fitting) code is successfully transplanted for HL-2A tokamak parameters. The evolution of the equilibrium configurations for shot 2898 is simulated. It is shown that the discharge starts with a limiter configuration and develops into a divertor configuration gradually after t = 200 ms. The latter lasts until the end of the discharge at t = 900 ms. The evolution of the major plasma shape parameters such as the boundary magnetic fluxes, the positions of the x-point and magnetic axis, and the minor radii obtained are calculated and compared with the experimental results. The agreement between the simulation and experiments are shown to be reasonable. The possibility for discharge quality improvement is discussed.

Studies of Reynolds stress and the turbulent generation of edge poloidal flows on the HL-2A tokamak

“…The position of last closed flux surface (LCFS) is set by the point where poloidal phase velocity of plasma fluctuations changes direction from the ion diamagnetic drift to electron diamagnetic drift [49,50]. This is verified by the equilibrium configuration reconstruction from EFIT [51] within the error ~2 mm. The depth that the probe shoots beyond the LCFS can then be inferred.…”

Doppler coherence imaging of scrape-off-layer impurity flows in the HL-2A tokamak

“…Figure 4(b) shows the projection of the tangent plane on the poloidal cross section obtained by the equilibrium configuration reconstruction from EFIT code. 40 The size of the projection area is about 927 × 580 mm 2 . The inboard vacuum chamber wall on the HFS is inside this area.…”

Experimental evaluation of Langmuir probe sheath potential coefficient on the HL-2A tokamak

“…Figure 1(a) shows the MHD equilibrium configuration which was reconstructed by EFIT [30] during limiter discharge. A fast reciprocating probe [31], was installed on the mid-plane.…”