Thermionic energy conversion for hypersonics

Spark Thermionics proposes to develop a design for thermionic devices that integrate directly into hypersonic vehicles. Thermionic energy conversion has the potential to leapfrog competing technologies but has largely been neglected for decades. Today, we have demonstrated best-in-class thermionic performance using novel materials and manufacturing techniques, as well as fully encapsulated prototypes meeting solicitation targets, including power density (1-10 W/cm2). Using these devices as a baseline, we propose to develop a new design that is compatible with harvesting heat directly from high temperature surfaces in the vehicle, relying on existing thermal pathways within the vehicle to simultaneously generate electricity while thereby displacing and reducing the vehicle thermal load. These devices can increase the Mach number in any vehicle and we believe will be enabling for long-duration and reusable hypersonic vehicles. If successful, our solution will add virtually no extra weight or volume vs the existing skin / liner, becoming the “APU” for all next-generation long-duration hypersonic vehicles.

Development of hypersonic capabilities is “the highest technical priority” according to Dr. Michael Griffin, DoD Under Secretary for Research and Engineering. However, for reusable and long-duration hypersonic vehicles, no good way to power the vehicle currently exists: a standard APU is not compatible with the lack of moving parts in typical hypersonic propulsion systems. For reusable and long-duration vehicles, of strong interest to NASA, we propose thermionics can become the "APU," generating power from existing high-T waste heat streams.

The applications outside of NASA are numerous for Spark's uniquely high power density technology. We have identified multiple commercial markets that value the small size and low weight of our generators, and we have received strong validation of scalable, compact generators from the Army, including SBIRs as well as being named finalists in xTechSearch 2.0 and AFC Innovation Combine.

This is early/mid-stage (TRL 5) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

None of these are guaranteed paths for this specific project — TechPort itself doesn't have an "apply" button. Reaching out to the contact(s) above with a specific question is usually the fastest way to find out what's actually open.