Plasma vertical stability and feedback control for TPX

The n=0 axisymmetric vertical stability and vertical position control have been examined for the Tokamak Physics Experiment. The passive stabilization is accomplished by using stabilizer plates close to the plasma. The present configuration is found to provide robust stability over a wide range of plasma parameters. The active feedback control of the plasma vertical position is done using coils located inside the vacuum vessel. These are required to control random disturbances leading to /spl les/1.0 cm RMS displacements from the midplane, and acceptable coil currents and voltages are found.