Stability of internally cooled superconductors in the temperature range 1.8 to 4.2 K

The stability of an Internally Cooled Superconductor (ICS) has been investigated experimentally at temperatures including both the HeI and HeII range. A NbTi/Cu cable was enclosed in a thin wall, tubular, stainless steel sheath for containment of the cooling helium, supported inside a vacuum chamber for complete isolation from external cooling sources, and positioned in the bore of a superconducting magnet that provided fields at the conductor of up to 8 T. The cable was subjected to well defined, sudden heat inputs by superimposing a high current pulse directly on the steady state transport current. Results are reported and compared to previous ICS stability data at 4.2 K and to predictions of performances at lower temperatures.