Analysis of the Current Charge and Discharge Characteristics of a Small-Scale Turn-to-Turn Soldered HTS Coil

Abstract

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.Index Terms-Charge and discharge, semipersistent, turn-toturn soldered.

Construction and test result of an all-REBCO conduction-cooled 23.5 T magnet prototype towards a benchtop 1 GHz NMR spectroscopy

“…The average resistance of individually measured six inner joints was 176.3 nΩ with a standard deviation of 1.8 nΩ and the average characteristic resistance, R c , representing an average radial-direction resistance of the NI DP coil, was 4.3 mΩ with a standard deviation of 0.3 mΩ.After finishing the initial liquid nitrogen test, we have applied In 52 Sn 48 solder on the top and bottom surfaces of each DP coil as an extra shunting for the extreme NI coil. This extra shunting reduces the contact resistance between turns and provides additional current paths if any defective part appears inside the coil[17,18].…”