Effects of Mechanical Vibration and Thermal Conductivity in Bi-2223 Tapes Using Ionic Liquid Impregnation

We prepared two kinds of ionic liquids (DEME BF4, DEME TFSI), and measured the thermal conductivity of the ionic liquids and the ac loss of the Bi-2223 tape using the ionic liquid impregnation under dc magnetic field in liquid nitrogen. As a result, the thermal conductivity of DEME BF₄ is approximately twice that of the epoxy. When the mechanical loss is maximum value, the loss can be reduced about 98.5% by using the ionic liquid compared with no impregnation. We consider that the tape impregnated into the ionic liquid is effective for reducing the ac loss. These results produce fundamental data to reduce the ac loss of conduction-cooled high-temperature superconducting coils.