An experimental study of catastrophic loss of vacuum for RHIC dipole in MAGCOOL

Experimental studies of catastrophic loss of insulating vacuum for RHIC dipoles to air and to helium have been performed in the Brookhaven MAGCOOL magnet test facility. A RHIC dipole was cooled to 4.5 Kelvin and powered to its 5000 Ampere design current prior to the test. Ambient air or helium was then introduced into the enclosure to simulate the vacuum loss conditions. The response of the cryogenic system, including the insulating vacuum, pressure, temperature and flow rate for the cooling helium, temperatures on the vacuum tank and heat shield are given as a function of time. The heat load is calculated from the sum of the heat into the magnet and the adjacent helium cooling pipes. The results indicate that for this system the heat load from a sudden loss of vacuum is of the order of 10 kW [0.086 W/cm2] for the helium test and 20 kW [0.17 W/cm2] for the air test. These are approximately one order of magnitude larger than the magnet quench heat load, and thus require special consideration of a pressure relief system for the helium cooling circuit