SUPERCRITICAL HELIUM COOLED, CABLED, SUPERCONDUCTING HOLLOW CONDUCTORS FOR LARGE HIGH FIELD MAGNETS.
Within the last two years the authors have developed a new concept of cabled superconducting hollow conductors able to recover from transient instabilities by virtue of on-going, single-phase helium cooling. The authors have been able to correlate small scale experimental results with an iterative computer program. The latter has been recently upgraded to include axial as well as radial heat transfer and predict more closely the chances of recovery. Success has been achieved in circulating nearly 1 g/s of supercritical helium in a closed loop using a high speed centrifugal fan and up to 10 g/s using a reciprocating single pulse bellows pump. The authors are currently in the process of adapting the loop to a 3 m length of a tightly wound 5000 A cabled hollow conductor equipped with pulse coils designed to fit inside a water cooled Bitter magnet. The combination will allow for a steady background field of 7. 5 t with a 2 t superimposed pulse.