The overall technical objective of the proposed Phase II program is to complete a system-level demonstration to show the capability and benefits of integrating this backup radiator/Variable Conductance Heat Pipe (VCHP) with the Advanced Stirling Radioisotope Generator (ASRG). The Phase I project developed a feasible VCHP radiator design that can be integrated with the ASRG. In Phase II, a trade study will be conducted to optimize the VCHP design. A superalloy heat pipe will be fabricated from Haynes 230, which has good strength at the 850o
C operating temperature and long term life tests with alkali metals. In addition to the VCHP, a General Purpose Heat Source (GPHS) simulator and a Heater Head simulator will both be designed and fabricated. Testing of the VCHP with the GPHS and Heater Head simulators will verify the ability of the VCHP to provide backup cooling for the Stirling convertors. The goal at the end of the program would be to bring the concept to Technology Readiness Level 5: Component Validation in a Relevant Environment.