System for controlling a superconducting coil with a magnetic persistent current switch

Abstract

The invention relates to a system for controlling a superconducting coil () with a magnetic persistent current switch (). The magnetic persistent current switch () is used for switching the superconducting coil () between a persistent mode and a ramp mode, respectively. The system further comprises a heat exchanger () configured to disperse heat to a cryocooler (), a loop tube () configured to enable flow of coolant to transfer thermal energy generated by the magnetic persistent current switch () to the heat exchanger (), and a thermal switch () comprising a valve () integrated with the loop tube () between the magnetic persistent current switch () and the heat exchanger (), the valve () comprising a valve body () with and inlet () and an outlet () with which the valve body () is connected to the loop tube (), a movable shaft () which is arranged inside the valve body () and which comprises a permanent rod magnet (), a latching arrangement () which comprises a permanent magnet (), and a solenoid (), wherein the shaft () is movable between a closed position in which the shaft () effects the closing of the inlet () or the outlet () of the valve body () and therefore no flow of coolant through the valve body is allowed, and an open position in which the inlet () and the outlet () of the valve body () are open and therefore flow of coolant through the valve body () is allowed, the solenoid () is arranged relative to the shaft () in such a way that by applying a current pulse with a first polarity to the solenoid () the shaft () is moved to the closed position, and by applying a current pulse with a second polarity to the solenoid (), the second polarity being opposite to the first polarity, the shaft () is moved to the open position, and the latching arrangement () is arranged relative to the shaft () in such a way that the magnetic force acting from the permanent magnet () of the latching arrangement () to the permanent magnet () of the shaft () forces the shaft () to stay in the closed position or in the open position, respectively, as long as no current pulse is applied to the solenoid () for switching the shaft () from the closed position to the open position or vice versa, respectively. In this way, a cooling system is provided that allows the temperature of the magnet persistent current switch () to rise and fall as desired within a short period of time, without straining the cooling system for the superconducting coil ().