Comparison of different ways of using superfluid helium to cool superconducting magnets

Several different schemes have been used or proposed for cooling large magnets using superfluid helium. These systems operate in three different heat transport regimes, depending on whether internal convection, forced convection, or both carry significant amounts of heat. A scheme is proposed for classifying global heat transport systems into four classes, and their essential thermodynamic characteristics are compared. Geometry is shown to have a large impact on temperature rise and cooling system performance. Some specific examples are shown for local heat transport between laminations of an accelerator magnet, and for global transport of the magnet heat load to the external refrigeration system.