Development of a prototype superfluid helium safety relief valve for the LHC superconducting magnets

A prototype safety relief valve for superfluid helium, contaminated with solid particles (10-700 mu m), is developed to protect the cooling system of the magnet strings of the intended LHC at CERN, against overpressure when the magnet string undergoes resistive transition. The development work mainly focused on the construction of a safety relief valve that operates reliably with contaminated medium. Different valve types have been designed, manufactured and tested. The results of the development will be summarized and discussed. (3 refs).