A Non-planar ReBCO Test Coil with 3D-printed Aluminum Support Structure for the EPOS Stellarator

Abstract: We report on the test of a small scale, non-planar coil using non-insulated ReBCO tape wound on a 3D-printed aluminum support structure. A 3D-scan of the winding frame which was printed out of AlSi10Mg using selective laser melting, showed peak manufacturing deviations of 0.3 mm. We tested the coil with 21 turns of 3 mm wide tape cooled both by liquid nitrogen and with a cryocooler. We achieved a central field strength of up to 21 mT which agrees with the prediction suggesting that we manufactured the coil without defects. The peak field was reached at a supply current of 120 A. The current leads showed a contact resistance of $\left(2.25\pm0.13\right)\mu\Omega$. The discharge time $L/R$ was found to be 0.63 s in liquid nitrogen and 2.92 s when cooled by the cryocooler. From this we estimate a winding pack temperature of 41 K.