Thermal conductivity in a sample simulating the winding structure of Bi-2223/Ag epoxy impregnated coils

We measured the effective thermal conductivity in samples simulating the structure of Bi-2223/Ag impregnated coils at liquid nitrogen temperature. We also studied the effect of the sample orientation with respect to the coolant surface: samples with the cooled surface in the horizontal and vertical positions were measured. The effect of heat drains located between the layers of the tape on the effective thermal conductivity was studied. Its increase is important for coils conductively cooled by refrigerators. Our experimental results are compared with those obtained by other authors using model calculations