Device for protection of superconducting magnets using a superconducting switch

A protection device for superconducting magnets is described, which provides evacuation of energy stored in the magnet both during the input (output) of the current and in the frozen-current mode. To provide highly effective energy evacuation the protection device incorporates, in addition to the superconducting jumper, a superconducting switch and a protective resistor. Structurally the superconducting switch constitutes a coil comprising a textolite frame with a bifilar stranded-wire double-layer winding. The heater element made of sheet steel embraces the winding and is separated from the latter by a layer of dacron-type material. The critical current of the superconducting switch is equal to 200 A, the resistance under normal conditions constitutes 41 Ohm at 10 K. Results of testing the working capacity of the proposed protection system are presented, which have been obtained during experiments on a seven-sectional solenoid (with the magnetic field in the center equal to 8 T) at a current of 150 A and a maximum stored eneAgy of 50 kJ. It has been found that the efficiency of energy evacuation constitutes 60-80% when simulating the transition of the solenoid into the normal state and 40% in the case of destruction of superconductivity