Ramping turn-to-turn loss and magnetization loss of a No-Insulation (RE)Ba2Cu3Ox high temperature superconductor pancake coil

Wang, Y. and Song, H. and Yuan, W. and Jin, Z. and Hong, Z. (2017) Ramping turn-to-turn loss and magnetization loss of a No-Insulation (RE)Ba2Cu3Ox high temperature superconductor pancake coil. Journal of Applied Physics, 121 (11). ISSN 0021-8979

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    Abstract

    This paper is to study ramping turn-to-turn loss and magnetization loss of a no-insulation (NI) hightemperature superconductor (HTS) pancake coil wound with (RE)Ba2Cu3Ox (REBCO) conduc-tors. For insulated (INS) HTS coils, a magnetization loss occurs on superconducting layers during aramping operation. For the NI HTS coil, additional loss is generated by the “bypassing” current onthe turn-to-turn metallic contacts, which is called “turn-to-turn loss” in this study. Therefore, theNI coil’s ramping loss is much different from that of the INS coil, but few studies have beenreported on this aspect. To analyze the ramping losses of NI coils, a numerical method is developedby coupling an equivalent circuit network model and a H-formulation finite element method model.The former model is to calculate NI coil’s current distribution and turn-to-turn loss, and the lattermodel is to calculate the magnetization loss. A test NI pancake coil is wound with REBCO tapesand the reliability of this model is validated by experiments. Then the characteristics of the NIcoil’s ramping losses are studied using this coupling model. Results show that the turn-to-turn lossis much higher than the magnetization loss. The NI coil’s total ramping loss is much higher thanthat of its insulated counterpart, which has to be considered carefully in the design and operation ofNI applications. This paper also discusses the possibility to reduce NI coil’s ramping loss bydecreasing the ramping rate of power supply or increasing the coil’s turn-to-turn resistivity.