Design analysis of plasma position control in SST1

For long-duration steady-state operation of the Steady-state Superconducting Tokamak (SST1), maintenance of the plasma radial and vertical positions within narrow limits would be crucial. For designing the position controller in SST1, we have adopted the simple linear RZIP control model. While the vertical position instability is slowed down by a set of passive stabilizers placed closed to the plasma edge, a pair of in-vessel active feedback coils can adequately control the perturbations to vertical position. The shifts in radial position due to minor disruptions would be controlled by a separate pair of poloidal field coils also placed inside the vessel. However, the radial position controller would ignore fast but insignificant changes in radius arising due to edge localized modes. Design considerations for the passive stabilizers and feedback control coils are discussed, and the simulations for vertical and radial position control using the RZIP model are presented. The parameters of both vertical and radial position control coils and their power supplies are determined based on the RZIP simulations.