Analysis of magnetic fields due to transformer coils in plasma formation and fusion applications

The magnetic null is of greatest significance for plasma formation in any Fusion Reactor device. In Ideal case, the radial and vertical component of the magnetic field produced by the Ohmic transformer coil should be approximately zero at some specific location inside the vacuum vessel. Non-zero radial & vertical component of the magnetic field within the plasma region acts as error field and causes difficulties in the gas breakdown. The error field effect can be compensated by placing the transformer coils in series with the solenoid coil. These coil positions must be estimated precisely for designed plasma current inception. This paper proposes a method to optimize the coil positions in order to obtain the null position at the described location inside the vacuum vessel. After optimal positioning of the coils, the magnetic field and plasma formation are analyzed using ANSYS, EFFI, and Poisson codes. The analysis is conducted at Plasma Research Lab. The results obtained with ANSYS simulation is validated with Analytical calculations.