Design and Prototype Testing of the Columbia Stellarator eXperiment (CSX) Non-Planar HTS Magnets

The rise of high-temperature superconductors (HTS) has accelerated the pursuit of fusion via magnetic confinement, enabling stronger magnetic fields and broader operational margins than conventional superconductors. However, the tape form factor of HTS poses challenges for adapting to non-planar stellarator magnets. We present work designing and testing non-planar HTS magnets for the Columbia Stellarator eXperiment (CSX), a quasi-axisymmetric device composed of two optimized non-planar interlocked HTS magnets and two copper stabilizing magnets. Prototype and eventual full-scale magnets consist of HTS tape wound and solder-potted in channels on 3D-printed aluminum frames. A gimballed winding mechanism maintains constant tension and mitigates strain during the winding process. Prototypes are tested at 77 K, then conductively cooled to 20 K target temperatures using a coldhead in a test-stand. Initial testing indicates a superconducting state was achieved with measured fields within 88% of predictions. Diagnostics and controls are interfaced with LabVIEW and include a high-current power supply, Hall probes, and temperature sensors. This work aims to enable the construction of an optimized university-scale HTS stellarator, addressing critical engineering challenges in the adaptation of HTS technology to stellarators.