Some results from the T-7 tokamak superconducting magnet test program

The first results from the superconducting toroidal coil test program for the T-7 tokamak are described. The coils, which have a cold mass of 12 tons and a field volume of 6m
³
, utilize a force-cooled circulation system. The system was cooled to 4.5K in 4 days using an HGU-250/4.5 refrigerator with a nominal capacity of 400W. The coils were initially charged to 4500A, and then to 4800A, or 75% of the critical current at 4.2K, which was achieved without quenching. At this current the magnetic field at the torus axis was 2.4T, the maximum field at winding 4T, and the stored energy 12MJ. Total charging time was 5 hours and the discharge time 20 minutes. The T-7 installation is now being prepared for plasma physics experiments.