Stability measurements on cored cables in normal and superfluid helium

The relative stability of LHC type cables has been measured by the direct h eating of one of the individual strands with a short duration current pulse . The minimum energy required to initiate a quench has been determined for a number of cables which have a central core to increase the effective inte r-strand cross-over resistance. Experiments were performed in both normal h elium at 4.4 K and superfluid at 1.9 K. Conductors in general are less stab le at the lower temperature when measured at the same fraction of critical current. Results show that the cored-cables, even when partially filled wit h solder or with a 'porous-metal' filler exhibit a relatively low stability at currents close to the critical current. It is speculated that the high inter-strand electrical and thermal resistance inherent in these cables may affect the stability at high currents. (C) 1998 Elsevier Science B.V. All rights reserved.