Ceramics: Mechanical properties, failure behaviour, materials selection

TLDR

The study investigates how a partially‑insulated winding scheme affects the discharge behavior of GdBCO coated conductor single‑pancake coils via sudden discharge tests. The authors fabricated three PI coil sets with insulation intervals of every 2nd, 4th, and 8th turn and four insulation angles (90°, 180°, 270°, 360°) to test discharge characteristics. Increasing insulation interval or angle extended discharge delay by enlarging insulated area, and the experimental results matched simulations, enabling the characteristic resistance to be estimated for practical use of PI coils in superconducting magnets.

Abstract

In this study, sudden discharge tests were performed on partially-insulated (PI) GdBCO coated conductor single-pancake coils to investigate the effects of a PI winding scheme on the discharge characteristics. Three sets of PI coils were constructed with insulation at 3 different intervals: every 2nd, 4th, and 8th turn. Each set included coils with 4 different insulation-angles: 90°, 180°, 270°, and 360°. Discharge delay of the PI coils was alleviated by increasing the insulation-interval or insulation-angle due to increased insulated area, which partially hinders radial current flow. The results of the sudden discharge test were in fairly good agreement with simulations of the PI coils using an equivalent circuit model consisting of a single RL circuit in parallel. The characteristic resistance of the PI coils was reasonably estimated through the numerical approach with contact surface resistance and compensation for the current-bottleneck effect, which enables the PI coils to be utilized in practical superconducting magnet applications.