Physics Design and Analysis of Pure Tension Bending Free Single Toroidal Field Coil for PST-I

The Pakistan Spherical Tokamak (PST-I) is the first medium-sized tokamak that will be installed in Pakistan. A pure tension toroidal field (TF) coil shape is suggested in order to get stable plasma operation and bending free TF coils. This paper utilizes pure tension theory for the design of TF coils. Numerical solutions of a modified form of File’s equation were employed to obtain the shape of the TF coil. The finite element method was used to find critical engineering parameters in the TF coil design. Excitation of the TF coil was done in two ways: steady state and transient state. Simulation results of the magnetic field profile, current density through the TF coil, Lorentz force distribution, stresses, and deformations/bendings are presented in this paper. Uniform stress distribution of around 5 MPa was observed in the pure tension TF coil during transient current excitation and 2.8 MPa during static current excitation. Maximum bending of 1.2 mm was observed in the TF coil during transient current excitation and 2 mm during static current excitation.