Transient cooling in internally cooled, cabled superconductors (ICCS)

Rapid heat transfer is reported in transiently heated copper capillaries containing stagnant supercritical helium. The hydraulic diameter and metal-to-liquid ratio of these capillaries are similar to typical ICCS characteristics and simulate ICCS heat transfer behavior. The characteristic cooling time of capillaries was found experimentally to be simply related to the heated length and speed of sound in helium. The ICCS stability margin could be estimated from the measured fluid temperature in the heated zone once equilibrium temperatures had been re-established. These experimental results can be predicted by a computer code. The code also predicts ICCS stability margins by accounting for induced helium flow. The correlation of experiment and theory seemingly supports the hypothesis that locally induced helium flow is responsible for unexpectedly high ICCS recovery characteristics.