Hysteresis losses in superconducting coil

The hysteretic losses of superconducting coils are measured and the results are compared with theoretical calculations. Wires used for coils are Nb-Ti twisted ones with 19 filaments. Coupling between filaments may be negligible, because they are insulated electrically from each other. Special care is also taken for the uniformity of magnetic field of the coils. The measured dependence of hysteretic losses on the magnetic field strength of coils agrees with the theoretical one and the loss energy density is irrelevant to the geometry of the coils.