COMPASS electrical systems and commissioning

The COMPASS experiment is designed to operate in both Pinch and Tokamak modes, the latter with both circular and shaped plasma cross-sections. In Tokamak mode, the primary windings are used as an inductive store with a two stage opening switch system to transfer the energy to the plasma loop. Three thyristor converters (total power 17MW) are used to maintain the plasma current, to provide vertical equilibrium field and to produce the required plasma shapes (e.g. dee, ellipse, etc). For Pinch operation, a conventional start bank/active crowbar circuit is used to feed a reconfigured winding arrangement. Three high power (each 250 kW) transistor amplifiers are used to energize other machine windings to provide vertical and radial correction fields for fast control of plasma position. A thyristor rectifier (40MVA) is used to supply the toroidal field system (92kA/turn for max. field of 2.1T). The control system uses programmable controllers controlled by a central computer. The operating interface is through touch-sensitive color monitors. 4 refs., 5 figs., 1 tab