Influences of geometrical configuration on AC loss measurement with pickup-coil method

We usually measure AC losses of superconducting wires and cables exposed to a transverse AC magnetic field by a pickup-coil method. In this case, a main pickup coil is coaxially located around the sample wire wound as a solenoidal coil. An additional pickup coil (a cancelling coil) is also placed inside or outside the sample coil. This method is advantageous to obtain detailed electromagnetic properties of the sample. In the present study, we discussed the effect of the geometrical configurations of the sample and pickup coils on AC losses measured by the pickup-coil method for three types of arrangements of the cancelling coils. We analytically calculated interlinkage magnetic flux into the pickup coils due to magnetic moments induced in the sample wire, and formulated the geometrical errors in the pickup-coil method. We also prepared some sets of sample and pickup coils, and compared observed AC losses with the theoretical predictions.