Investigation of index heating as source of quench in the NHMFL 45-T hybrid superconducting outsert

The superconducting outsert of the NHMFL 45 T is cooled by static He II contained in cable-in-conduit conductors, which must be capable of extracting any internal heat (primarily from hysteresis losses) during a ramp to full field. In the event that the ramping losses exceed the cooling capacity of the He II, the long cooling channels become partially or completely filled by He I and even the relatively weak heating of index losses can lead to slow thermal runaway and a delayed quench. A numerical analysis is presented using a one-dimensional model of heat transfer in a column of superfluid helium. The computational results are compared with experimental data, showing good agreement with the observed quench behavior.