Description: Between 1998 and 2003, Hi-Z Technology developed and built a 40 mW radioisotope power supply (RPS) that used a 1 watt radioisotope heater unit (RHU) as the energy source. This RPS represented a continuation of 30 years of development that began in the Thermoelectrics Division of General Atomics in the 1960's. This system is the most efficient of its size to this day, and has been validated by extensive life testing. We now propose to devise improvements to the design giving it increased resistance to mechanical shock. In the Phase I we will conduct simulations to inform a trade study examining multiple options of up to 10,000 G of shock tolerance and up to 40 mW of output power. We will also build TEM modules for destructive testing to measure mechanical properties. In Phase II, we will fabricate prototypes that use electric heaters and weights to simulate an RHU. These will be subjected to shock testing at NASA Ames. After iterations of design, build and test, we will present a new RPS design that offers valuable new mission capabilities to the space program.

Benefits: The proposed system is a power supply about the size of a soda can which can reliably produce electric power in the 40 mW range for in excess of 20 years. It will be hardened against mechanical shock to survive launch and impact on the surface of planetary bodies. This will be an enabling technology for dozens of small, low cost missions for data collection throughout the solar system.

Because this RPS system relies on a plutonium-based heat source, it cannot be sold anywhere in the private sector. However, the thermoelectric module (TEM) at its core could have widespread commercial application as an energy harvesting power source for wireless sensors. These devices would use temperature gradients from their environment to scavenge energy and convert heat flows into electric power. This could be a huge benefit in any application where the sensor's location makes it difficult to access for periodic battery replacement. For example, wireless self-powered sensors and controls along air ducts in large HVAC systems could enable more energy efficient heating and cooling. There could also be implanted medical applications using differences between skin and core temperature to produce electric power for a sensor or therapeutic device.