Measuring transport AC losses in YBCO-coated conductor coils

Several AC power applications of YBCO-coated conductors (CCs) involve superconducting tapes wound in coils. In such a configuration the superconducting tape is arranged as closely packed turns, which strongly interact due to the generated magnetic field. This has a strong influence on the AC losses, which are different from those of an isolated tape, and need to be precisely quantified in order to predict and reduce the refrigeration requirements of applications. In this paper we experimentally evaluate the transport AC losses in a pancake coil composed of 25 turns of superconducting tape. We describe in detail the measuring technique utilized, pointing out the issues in this kind of measurement. We also present preliminary results of AC loss computation by finite-element modelling.