CALORIMETRIC AC LOSS MEASUREMENTS OF SILVER-SHEATHED BI-2223 SUPERCONDUCTING TAPES

A new calorimetric method has been developed to measure ac losses in s uperconductors. Calibration of the losses requires a reference heater of the same size and shape as the superconductor mounted in a symmetri c environment. Its main advantage is the direct determination of the t otal losses. Variations of the method include a null technique and ave raging of the main Fourier component to reduce noise effects. The meth od 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 o ther groups with other methods.