High Thermal Conduction Bobbin and Thermal Stability of Conduction Cooled Superconducting Pancake Coils

We have proposed a Dyneema fiber reinforced plastic (DFRP) as a coil bobbin material. The DFRP has some properties such as high thermal conduction, easy mechanical processing, and expansion with cool down. We fabricated superconducting coils having an YBCO tape, cooled the coils with a refrigerator, and supplied a dc current to the conduction cooled coils. Thermal stability of the coils was also estimated. The DFRPs, glass fiber reinforced plastics, and AlN blocks were used as the bobbin materials for the coils. From the experimental results, the thermal stability of the coils increased with increasing of the winding tension of the coils, and the coil having the DFRP bobbin showed better performance than the coils with the glass fiber reinforced plastic and the AlN bobbins. We think that contact force between the superconducting tape and the bobbin became large due to the thermal expansion of the DFRP bobbin. These results showed that DFRP can represent a viable opportunity as bobbin material for conduction cooled high-temperature superconducting coils.