Graphene-Cu Hybrid Foil Thermal Straps for Conduction Cooling of SRF systems

Statement of problem or situation being addressed: The sluggish conduction cooling rate of conventional thermal straps made from copper, aluminum, or graphite hinders the application of thermal straps to compact accelerators and superconducting radio frequency technologies. Advanced materials with high performance properties hold the key for thermal straps, effectively balancing device heat dissipation with cryocooler capacity, and reducing conduction cooling time, enabling faster operation. Space platforms and high-power electronic systems require next-generation high thermal and electrical conductivity materials for fast conduction cooling and/or low resistance electrical pathways.Statement of how problem is being addressed: This project will develop and validate an efficient, scalable, manufacturing-ready approach for production of high-performance graphene-copper hybrid foils/coatings, and demonstrate their application in thermal straps, electronic devices, and space landing systems. This technology utilizes the intrinsic physiochemical, thermal and mechanical properties of graphene and copper matrix, combined with advanced electrodeposition techniques for hybrid material fabrication. This technology can tailor graphene-copper hybrid properties for operational performance, making the hybrid material an ideal thermal strap or coating for fast conduction cooling processes and/or low electrical resistance requirements.What was done in Phase I? Manufacturing processes to fabricate graphene-copper hybrid foils were developed. Fabricated hybrid foils exhibited ~50% sheet resistance reduction and ~50% mechanical strain increase compared to pure copper foils. Thermal conductivity, measured by the stepped-bar method, increased with the incorporation of graphene in the copper matrix, adjusted for surface roughness. Government users and commercial partners were identified.What is planned for Phase II? Phase II will mature and scale the production of graphene-copper hybrid foils with both incorporated and laminate structures. The graphene-copper hybrid foils will be assembled into thermal straps for SRF cavities and cryocoolers. The performance of individual foils and assembled thermal straps will be evaluated. The hybrid foil manufacturing parameters will be customized based on both DOE applications in thermal straps and identified commercial applications in electronics, and space systems. The cost analysis will be refined and a technology transfer plan and business case based on the commercial interests of our partners will be further developed.Commercial Applications and Other Benefits: Copper-graphene hybrid materials are of interest to entities with advanced thermal management needs using conduction cooling, including NASA and Air Force. The proposed technology is anticipated to attract interest from markets for high-powered electronics and space landing systems, which use conduction cooling technology for heat transfer or high conductivity backplanes as low resistance electrical pathways.