Study on transient cooling characteristics of superconducting magnet by superfluid helium with phase changes

A numerical model is presented to analyze the stability of the internally cooled composite superconductors cooled by superfluid helium with phase changes taken into consideration. To simulate the unique characteristics of superfluid helium, the momentum difference term between the actual momentum and the homogeneous one is derived, which is added to the conventional Navier-Stokes equation. Numerical analyses are performed to study the quenching process in a system of a one-dimensional composite superconducting magnet that is locally heated. Transient temperature profiles are numerically obtained for the superconductor as well as the helium. The validity of the model is discussed. It is clarified that the model simulates well the evolution of the quenching process of the superconductor as well the phase changes in the helium flow. (author)