Analysis of the current charge and discharge characteristics of a small-scale turn-to-turn soldered HTS coil

A semipersistent current-mode operation with a high-temperature superconducting (HTS) coil is very useful for some applications, including maglev. An HTS coil for semipersistent mode operation includes at least one residual joint to make a closed-loop coil. A low current decaying rate is achieved by reducing the residual joint resistance. This paper suggests a winding method with a turn-to-turn soldering process. The turn-to-turn soldering process provides a wide flow path for the charged current in the HTS coil during the semipersistent mode operation. Therefore, the total equivalent residual resistance is reduced. However, this reduced residual resistance also prevents the current from participating in the charging process. Therefore, a new current charging method for the turn-to-turn soldered HTS coil needs to be tested. In this paper, a small-scale sample HTS coil with turn-to-turn soldering method is fabricated for testing. A simple charging-discharging experiment is performed on the sample coil. The time constant of the sample coil is calculated from the experimental results. A fast current charging sequence for the turn-to-turn soldered coil is also tested and analyzed from the perspective of power and energy consumption during the current charging operation.