Overview of the new Magnet Power Supply Systems of JT-60SA procured by EU

Abstract

JT-60SA, the superconducting tokamak under construction in Japan, will be equipped with a mix of new and reused Power Supply Systems. Most of the new Power Supply Systems are procured by European Voluntary Contributors under the framework of Broader Approach agreement between Europe and Japan.For the toroidal circuit, the 25.7kA steady state ac/dc converter is procured by CEA. For the poloidal circuits, the procurement of 10 ac/dc converters, almost all rated ±20kA and about ±1kV is shared between CEA and ENEA. The two in-vessel coils for fast control of plasma position are supplied with two independent thyristor converters procured by ENEA, each one rated ±5kA and ±1kV. The operation of four Switching Network Units procured by ENEA inserts settable resistors in series to each Central Solenoid module, producing up to 5kV at the nominal current of 20kA and allowing stable plasma initiation. The protection of toroidal and poloidal superconducting magnets is assured by thirteen Quench Protection Circuits procured by Consorzio RFX, rated ±20kA and ±3.8kV for poloidal coils and 25.7kA and 2.8kV for toroidal ones, inserting a discharge resistor in the related circuit for fast dissipation of the magnetic energy stored in the coil. Finally, the suppression of Resistive Wall Modes is actively performed by 18 in-vessel coils, independently supplied by a corresponding number of fast inverters procured by Consorzio RFX, each one rated for 300A and 240V.The key aspects of the design of the aforementioned Power Supply Systems are described in the paper, informing also about the present status of the procurement: their design was completed and some systems were already manufactured, tested and delivered to Japan.