Type Tests of JT-60SA Central Solenoid/Equilibrium Field Superconducting Magnet Power Supplies

JT-60SA is a superconducting tokamak in the framework of the broader approach agreement between Europe and Japan. For this international project among its various procurements, the Italian National Agency for new technology energy and sustainable economic development (ENEA) is providing four ac/dc converters for the central solenoid (CS) superconducting magnets, two ac/dc converters for the equilibrium field (EF) superconducting magnets, and two ac/dc converters for the fast plasma position control coils (FPPCC). Furthermore, ENEA is also providing six converter transformers of which four are of the dry type for FPPCC power supplies (PSs) and two of oil type for CS PSs. CS/EF PSs feed poloidal superconducting magnets of JT-60SA, whose purpose is the generation of strong magnetic fields able to induce and confine the plasma current in a prefixed geometrical configuration. The control system of CS/EF PSs has to be able to reproduce in real-time a reference current or voltage profile, known as “scenario” and these are particularly critical in these systems for the high currents required and for the high magnetic energy stored in the superconducting magnets. All performed type tests, carried out in accordance to the IEC60146 Standards, pointed toward a good dynamic behavior of the control system both for forward and for reverse rectifier bridges, assuring the smooth transitions between different operating modes: single mode, circulating current mode and dual mode. This is the focus of this paper.