Low AC-loss MgB2 Superconductors for Turbo-Electric Aircraft Propulsion Systems

The development of magnesium diboride (MgB2) superconducting wires makes possible the potential to have much lighter weight superconducting stator and rotor coils for heavy aircraft motors and generators than with any other metal or ceramic superconductor. The MgB2 superconductor can be cooled to 20 K by liquid hydrogen fuel or conductively with a cyrocooler. The lighter weight coils, especially in the stator, will enable a lighter weight motor/generator. In a NASA SBIR Phase I and Phase II program we want to develop low AC loss MgB2 superconductors for the stators of synchronous motors or generators. For turbo-electric aircraft propulsion systems, it is desirable to have very light weight superconducting wires that can operate at greater than 1.5 T field and 500 Hz electrical frequency with input power between 10 and 100 kW. This SBIR Phase I aims to design, fabricate, and characterize AC-tolerant superconductors with a targeted loss budget less than 10 W/kA-m. This will be accomplished by reducing the hysteretic losses in MgB2 superconductors by fabricating wires with very small filaments, reducing the eddy current component of AC losses in MgB2 superconductors, and characterizing the transport current and AC losses of MgB2 wires.