Evaluating Cooling Performance of High-Thermal-Conduction Composite in Conduction-Cooled Superconducting Coils

Aluminum nitride (AlN) has been widely used as a heat sink material in conduction-cooled superconducting coils but is hard to process. We have therefore developed an easily processed Dyneema-fiber-reinforced plastic (DFRP) with high thermal conductivity. Making small superconducting coils with DFRP or AlN bobbins, cooling them to a cryogenic temperature by using a refrigerator, and comparing their voltage profiles when DC currents were applied to them, we found the heat-sink effect of DFRP to be almost same as that of AlN because DFRP has a high thermal conductivity and expands when cooled. This expansion increases the contact force between superconducting windings and the DFRP bobbin and thereby improves the transfer of heat from the winding to the DFRP. We think DFRP will be the next-generation heat-sink material.