This technology was developed to address the limitations of traditional, single-fed linear alternators that require permanent magnets, adhesive bonding organics, and heavy iron laminations for flux control. They experience eddy-current losses and require electromagnetic interference protection. Furthermore, they have a limited operational temperature range (only up to 250 °C), which typically declines to below 200 °C as the adhesive bonding organics outgas and degrade over time. Consequently, they are limited to approximately 93% efficiency at ambient temperatures.

Glenn's linear alternator addresses all of the limitations of its predecessors and engenders a number of desirable new qualities — notably, the ability to reduce eddy-current losses by 25% and operate at 99% efficiency at temperatures up to 950 °C. It features a concentric, additively manufactured, monolithic copper plunger and stator. The stator is a stationary, single copper Halbach array, whereas the plunger is a moving, electromagnetic copper Halbach array.

A direct current is delivered through the conductive piston flexure support, which also provides reactive power for resonance. It creates a fixed magnetic field similar to that of a permanent magnet, but the magnetic field is channeled inward by the Halbach mover, doubling its strength.

By utilizing standard double-fed induction control methods, the reactive power can be transferred and adjusted between both coils. When used with the double-action, extremely light, thermo-acoustic (DELTA) converter, the engine/alternator system is one-tenth the weight of a traditional system. This innovative technology will enable a new class of vastly superior linear alternators with the ability to operate at extreme temperatures with increased performance and efficiency.

NASA is actively seeking licensees to commercialize this technology. Please contact the Technology Transfer Office at This email address is being protected from spambots. You need JavaScript enabled to view it. or 216-433-3484. Follow this link here for more information.