Pressure Rise Analysis in Superconducting Coils during Dumping

Abstract

An abrupt helium pressure rise in a superconducting coil due to dumping has the possibility of causing not only coil case failure but also expansion turbine damage in the associated refrigerator. Analysis of the pressure rise is indispensable in the design of a large superconducting coil regardless of its cooling type in order to identify the maximum operating pressure in the helium circuit and helium loss when the relief devices open. The set pressure and the size of the safety devices installed on a coil and the proof-pressure of a coil are decided on the basis of this analysis to prevent coil failure even in an instantaneous quench of the entire coil. The maximum pressure in a coil during dumping basically depends on the heat generation, the initial helium inventory, the nominal operating pressure, and the set pressures and sizes of safety devices. Although a few papers 1,2,3 on pressure rise of a superconducting coil with internally cooled conductors are published, nothing is found on a pool-boiling superconducting coil.