Investigation and analysis of turn-to-turn contact resistance of a no-insulation YBCO pancake coil under time-varying

This paper is focused on the turn-to-turn contact resistance as a major source of the characteristic resistance of no-insulation YBCO pancake coil. Usually, the characteristic resistance of the coil is calculated by measuring decay time constant. However, we identify that the turn-to-turn contact resistance is not a constant value and changes with time. In order to verify this, one single pancake NI HTS coil consisting of 27 turns were fabricated with winding tension carefully maintained at a constant level. Through charge, discharge and sudden tests under time-varying, we obtain curves of the axial field at the centre, coil end-to-end voltage and an output current of power supply. In this paper, results show that the turn-to-turn contact resistance of NI coil varies with the time.