Calculation of Coil Currents for Equilibria with Reversed Plasma Current Density in J-Text Tokamak

To design the alternating current operation of the J-text tokamak, this paper studies the plasma equilibrium during the plasma toroidal current reversing. First, four alternative current reversal equilibrium configurations with circular cross section when the total toroidal current becomes zero were constructed. Then, the profile of the plasma current was used as the input of a fixed boundary equilibrium solver to calculate the poloidal field coil currents. According to the results, the relationship between the plasma current distribution and currents in ohmic heating coils and vertical field coils is discussed. Finally, the plasma equlibrium of a toroidal current reversal with total plasma current from 40 kA to –40 kA in 40 ms was designed.