Calculation of the Poloidal Magnetic Field Configuration for the J-TEXT Tokamak

Two approximate analytical methods are used to calculate and analyze the poloidal magnetic field configuration for the J-TEXT tokamak, an iron core tokamak. The methods are based on a spool model and an infinite length model, respectively. By comparing the calculated results with the experimental data, the two methods are modified by the least square method. The results given by the modified method based on the spool model shows good agreements with the experimental data. The modified method based on the spool model replaces the similar function in a general equilibrium code, EFIT. The displacements of the centriod of the plasma current in the J-TEXT tokamak reconstructed by the revised EFIT are coincident with the results measured by the soft-X ray array and magnetic probes.