Manufacturing and testing of AMaSED-2: a no-insulation high-temperature superconducting demonstrator coil for the space spectrometer ARCOS

The Astroparticle Research Compact Orbital Spectrometer (ARCOS) magnet is a 12-coil toroidal magnet for a proposed next-generation magnetic spectrometer in space. AMaSED-2 is a small-scale non-flight demonstrator coil for the ARCOS magnet. AMaSED-2 consists of two individually built no-insulation high-temperature superconducting pancake coils with racetrack-like shapes. The two pancake coils are contained in a total of 724 m of 12 mm wide SuperPower REBCO HTS tape. Copper bands functioning as current leads and layer jump surround the winding blocks. An aluminum structure mechanically supports the coil assemblies. AMaSED-2 was manufactured and tested at CERN. The coil was tested in cryogenic helium gas at various temperatures between 10 K and 77 K by measuring the center magnetic flux density while varying the operating current. We employ a model for no-insulation coils and identify for each temperature the center magnet constant and magnet charging time constant as system parameters. We also determine the radial resistance, peak magnet constant, magnet critical current, and maximum achieved magnetic flux densities. Central magnetic flux densities up to 2.9 T were measured, corresponding to a peak magnetic flux density on the coil of 9.7 T. The design and characterization of AMaSED-2 provides a basis for future magnet development of a flight model.