SiGe RTG Unicouple Testing Capabilities

The Jet Propulsion Laboratory (JPL) Thermal Energy Conversion Group has been steadily increasing its thermolelectric (TE) fabrication and testing capabilities since its foundation in the 70s. It has a heritage of making thermoelectric devices from powder processing, all the way to life testing of thermoelectric devices or Electrically heated Thermoelectric Generators (ETG). The Next Generation Radioisotope Thermoelectric Generator Project (Next Gen RTG Project) is currently re-establishing the capability to manufacture heritage based GPHS-RTGs1. These RTGs will use the Heritage General Purpose Heat Source (GPHS)2 step II as thermal source with more than five hundred heritage-like silicon germanium (SiGe) unicouples3 for thermoelectric conversion. Radially oriented radiative fins around the RTG’s cylindrical housing will dissipate the waste heat in a way that maintains the desired temperature gradient across the SiGe thermoelectric unicouples with hot- and cold-sides at approximately 1,000°C and 300°C.JPL is supporting the Next Gen RTG Project, including providing Independent Verification and Validation (IV&V) of SiGe based thermoelectric unicouples performance for lifetime performance prediction.This paper describes the test itself, the test setup and fixtures, preliminary test results of JPL-built SiGe unicouples, and an overview of JPL’s unicouple testing capabilities.