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Description
In the context of accelerator and fusion magnet applications, high-temperature superconducting (HTS) coils must maintain stable performance over extended periods post-installation, during which they undergo multiple thermal and magnetic cycles. This study investigates the stability of REBCO MI/NI coils under repeated thermal cycling and periodic electromagnetic loading. The degradation of Ic performance, observed after multiple thermal-magnetic cycles, can be attributed to cumulative thermal stresses and electromagnetic forces that induce deformation. Such deformations lead to significant strain and localized stress concentrations within the coils. Notably, MI and NI coils exhibited an increasing delay time with the number of test cycles during liquid nitrogen evaluations, hinting at the presence of irreversible deformations accrued through repetitive testing. This paper summarizes the performance characteristics of MI/NI coils following multiple cycles and compares these findings with coils cured in paraffin.
