Training of the position controller in SST-1 using TSC simulations

Abstract

For sustenance of the long duration discharges in the Steady State Tokamak (SST-1), it would be necessary to accurately measure and control the plasma shape, radial and vertical positions. While the plasma shape and position would be controlled by a set of superconducting coils placed outside the vessel and copper feedback control coils placed inside the vessel, their diagnostics would be carried out by an array of magnetic probes placed inside the vessel, just outside the first wall. The main objective of this paper is to demonstrate the reconstruction of plasma position and shape parameters from magnetic probe measurements in steady-state operation. Function parametrization method would be employed to infer the plasma position and shape parameters from the probe signals, which needs large volume of prior database for the probe signals for various plasma positions and shape parameters. This has been generated through SST-1 discharge simulations using the Tokamak Simulation Code (TSC), which generally has excellent agreements with experimental data. The discharge simulations using TSC over a wide range of SST-1 plasma parameters and use of the corresponding database in fitting of plasma position and shape parameters to probe signals are presented. It is also shown that the subsequent reconstruction of plasma position and shape from test data also generated from TSC simulations is well within the error limits.