Design of the ohmic system for SST-1

The conceptual design of SST-1 tokamak has been finalized at the Institute of Plasma Research. The SST-1 tokamak is being designed as a steady state tokamak with superconducting toroidal and poloidal field magnets, RF and neutral current drives and RF current heating. While the plasma equilibrium and shaping is provided by the superconducting poloidal field coils, plasma start-up and current ramp-up upto certain extent is desirable by a resistive ohmic transformer, as the stability of superconducting cable demands a limited rate of change of current in these coils so as to avoid the quenching in these coils and thus rules out the possibility of using these coils for the plasma start-up. The ohmic transformer consists of a central solenoid and two sets of compensating coils, which are required to minimize the stray fields of central solenoid in the plasma volume. The design of central solenoid and the compensating coils along with the thermal requirements is discussed. The Lorentz forces and internal stresses resulting from them are also presented