Simulation of the breakdown in TEXTOR

The optimal conditions of the gas breakdown in the new option of TEXTOR tokamak with increasing flux swing were found. The stray poloidal magnetic field inside the vessel generated by the inductor current was found by numerical solution of the 2D magnetostatic problem. The conditions of the compensation of this field by currents in the poloidal field coils were obtained. The minimal breakdown voltages in the uncompensated and compensated magnetic configurations were calculated.