Minimum quench energy measurements on prototype LHC inner cables in normal helium at 4.4 K and in superfluid He at 1.9 K

The minimum energy of short duration (MQE) required to quench superconducting cables at fixed field for currents close to the critical current has been measured for several prototype LHC inner type cables. Measurements done both in normal helium at 4.4 K and also in superfluid helium at 1.9 K show that the level of cable compaction has a substantial effect on the conductor stability. It also appears that another parameter that significantly influences the ability of the conductor to absorb transient energy pulses is the inter-strand resistance, which can vary greatly depending on the cable design and the nature of the strand surface. This parameter seems to make a bigger difference to MQE at 1.9 K than at 4.4 K. Details of these measurements are presented.