Calorimetric ac loss measurements of silver sheathed Bi-2223 superconducting tapes

A new calorimetric method has been developed to measure ac losses in superconductors. Calibration of the losses requires a reference heater of the same size and shape as the superconductor mounted in a symmetric environment. Its main advantage is the direct determination of the total losses. Variations of the method include a null technique and averaging of the main Fourier component to reduce noise effects. The method has been tested on Bi-2223 tapes and gives the expected hysteresis losses as well as a frequency independent loss which can be attributed to flux creep. The measured losses are similar to those obtained by other groups with other methods.