Solenoid and Racetrack Coils Wound from MgB2 Strand

Results from measurements on five racetrack coils and one solenoid coil are reported in this work. Three of the racetracks were wound with monofilamentary strand, and two from multifilamentary 19‐stack strands. The solenoid coil was wound from 7‐stack multifilamentary strand. Some strands had Fe barriers, others Nb, some had none. Outer sheaths of pure Cu, Cu‐30Ni, and monel were investigated. S‐glass insulation was used in all cases. Some coils were potted in CTD101, others in Stycast. Transport Jc measurements were performed initially in liquid helium, and then as a function of temperature up to 30 K. The highest result at self field was 400 A at 12 K for a racetrack coil. This coil had a Jc of 200 kA/cm2, a Je of 50 kA/cm2, and a winding pack Je of 26 kA/cm2, all as measured at 12 K. The 20 K results were Ic = 260 A, Jc = 130 A/cm2, Je = 32.6 kA/cm2, and Jw = 17.5 kA/cm2. The B field generated by the racetrack was 0.44 T at 12 K and 0.29 T at 20 K. The solenoid coil critical current was lower than this...