Measurement of a Conduction Cooled Nb3Sn Racetrack Coil
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Publisher:IOP Publishing Ltd
Citation:HS Kim et. al. 2017 IOP Conf. Ser.: Mater. Sci. Eng. 279 012018. https://doi.org/10.1088/1757-899X/279/1/012018
Use of superconducting coils for wind turbines and electric aircraft is of interest because of the potential for high power density and weight reduction. Here we test a racetrack coil developed as a proof-of-concept for cryogen-free superconducting motors and generators. The coil was wound with 1209 m of 0.7-mm-diameter insulated tube-type Nb3Sn wire. The coil was epoxy-impregnated, instrumented, covered with numerous layers of aluminized mylar insulation, and inserted vertically into a dewar. The system was cooled to 4.2 K, and a few inches of liquid helium was allowed to collect at the bottom of the dewar but below the coil. The coil was cooled by conduction via copper cooling bars were attached to the coil but also were immersed in the liquid helium at their lower ends. Several current tests were performed on the coil, initially in voltage mode, and one run in current mode. The maximum coil Ic at 4.2 K was 480 A, generating 3.06 T at the surface of the coil. The coil met the design targets with a noticeable margin.
A Nb3Sn coil was fabricated, cooled, and tested. A small amount of liquid helium below the coil was used as the cold reservoir with the coil cooled by conduction through the cooling legs. The operational current target of I = 435 A was achieved, with both current (45 A) and temperature (3.8 K) margin. The field values reached 3 T at the outer can of the coil, as expected by modelling. The coil met the needed targets for the winding design with a noticeable margin.
Funded by a NASA Learn Program