A High-Performance Cryovacuum Rotary Slip Ring Union

The Air Force tests and calibrates visible and infrared radiometric sensors for interceptor aircraft and space surveillance systems using test facilities that simulate the high-vacuum, cryogenic conditions of high-altitude flight and space. Simulation of continuous vehicle roll and variations in the test object’s temperature compared to the background environment is important and requires a new rotary fluid and electrical feedthrough capability with thermal isolation. Creare proposes to develop a new high-performance cryovacuum rotary slip ring union (SRU) that provides continuous rotation pass-through capability for electrical power channels, low-noise signal channels, and two or more cryogenic fluid channels. Our SRU approach is compatible with high-vacuum conditions and operates from ambient temperatures down to below 80 K. It provides high thermal resistance between the fluid channels and the mounting flange and between the source and return fluid channels themselves. In a Phase I project, Creare designed and successfully developed a proof-of-concept cryovacuum SRU prototype and conducted testing and analysis to demonstrate the baseline performance of key materials, design features, and components together and their ability to meet the requirements for vacuum compatibility, thermal isolation, signal noise, and service conditions. The key subsystem technologies performed as anticipated in limited laboratory tests, except that the cryogen seal leak rates were higher than anticipated, likely due to inadequate test component quality. In response to the seal leak rate results, an enhanced backup sealing approach was conceptually developed that promises fully hermetic seals and low-risk development. The Phase I project also developed a conceptual design for a fully functional cryovacuum rotary SRU prototype that will be suitable for Air Force test facilities. In this Phase II project, Creare proposes to develop, test, and deliver a fully functional cryovacuum rotary SRU prototype for an Air Force test facility. The project will complete the new rotary seal development, verify the performance of key subsystems, develop a detailed prototype design, and fabricate a fully functional cryovacuum rotary SRU prototype. The prototype will undergo laboratory testing to verify functionality and will then be delivered to the Air Force. This technology development will result in cryovacuum rotary SRU technology and products that meet the above Air Force testing needs and form a basis for custom products for other space and research applications.