Equilibrium Reconstruction and Equilibrium Properties in QUEST Tokamak

Plasma shape reconstruction is an important part of tokamak data analysis. An off-line plasma shape reconstruction, based on the EFIT code in Linux system, can be carried out in Q-shu Univ. Experiment in Steady-State Spherical Tokamak (QUEST). In this paper, the algorithm about equilibrium reconstruction is described in detail. Magnetic reconstruction in QUEST, which is calculated by the EFIT code according to the external magnetic measurements, is introduced and the results are presented in detail. It is known that the eddy current effect is large in QUEST experiment, the eddy current effect is first considered into equilibrium reconstruction. Fourier expansion is applied to reconstruct the vessel current distribution in EFIT code. To test the accuracy of the result, a comparison with the result of Cauchy condition surface method has made, which suggests the reliability of the result. A visualization interface is made, which is convenient for physicists and operators to analyze the behavior of plasma. At the same time, the operation space of elongated discharges is discussed based on the QUEST database. The real time EFIT will be applied to the plasma control system of QUEST in the future.