Low AC-loss MgB2 Superconductors for Turbo-electric Aircraft Propulsion Systems, Phase I

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.

Potential NASA Commercial Applications: Manufacturers of large electrical systems desire to increase the efficiency, and decrease the size and weight of their systems in order to reduce costs. Presently manufacturers of transformers, motors, generators, fault current limiters, transmission cables, and magnetic resonance imaging (MRI) systems are pursuing superconductor wires to achieve these objectives. To make major cost improvements with superconducting systems, the barriers have been the higher cost of cooling at liquid helium temperature (4 K) for traditional metallic superconductors and the high wire cost for ceramic high temperature superconductors at 20-30 K temperatures. Low cost MgB2 superconductor wires operating at 4 25 K can overall lower the upfront and ongoing operational costs of superconducting systems. Potential Non-NASA Commercial Applications: Besides stator and rotor coils, magnesium diboride superconductors can benefit NASA applications for many applications where light weight power components are required such as cables, generators, motors, transformers, inductors, and power conditioning equipment. Other magnet applications that magnesium diboride wires can be considered for are magnetic shielding in space applications, ADR coils, magnetic bearings, actuators, MHD magnets, and magnetic launch devices.