Quench Test and Analysis on D-Shaped No-Insulation High Temperature Superconductor Single Pancake Coil

No-insulation (NI) high temperature superconductor (HTS) magnets are indeed an innovative technology in various fields that require a high magnetic field. In nuclear fusion applications, this technology may enable the realization of the fusion energy in the compact, high magnetic field fusion pathway. Yet, the development of toroidal field (TF) coil for compact tokamak is still ongoing, mainly in the private sectors such as Commonwealth Fusion Systems and Tokamak Energy, confronting many new challenges regarding large-scale NI HTS magnets which are mostly in the area where intensive research is required. Among the challenges, the design and measures to avoid quench are of high importance and should be dealt with throughout the design stages to ultimately achieve the target field and reliable operation. In this paper, we fabricate a laboratory-scale D-shaped NI HTS single pancake coil and proceed with consecutive quench tests. A modified lumped circuit model is used to estimate the different contact resistances in different sections of the coil and to analyze a quench case. Although the replication of the quench experimental data was not successful, discussions are made to point out the considerations in the quench study of NI HTS coils.