SITIS Topic Details |
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| Proposals Accepted: | |
| Program: | STTR |
| Topic Number: | AF10-BT02 (AirForce) |
| Title: | Optical Cryocooling for Space-borne Sensors | Research & Technical Areas: | Space Platforms |
| Objective: | To develop concepts for a compact solid-state cryocooler for space applications based on optical refrigeration. This enables vibrationless microscale coolers to support AF IR space missions.
| Description: | Next generation Air Force space infrared sensing technologies and on-board cryogenic cooling needs will require improvements in component level technology that reduce payload jitter, mass, and power budgets through improved thermal management of cooling loads and rejected heat. Sensor sensitivity in general depends on reducing the background noise due to thermal fluctuations and stabilizing the device’s temperature dependent calibration. Active localized cooling can be used to prevent thermal run-away in high-density processor chips, and processing speed is increased by decreased resistance. The thermal solution is microscale, vibrationless cryocoolers, which have become high interest items for the Air Force (especially for operationally responsive space) in order to reduce thermal fluctuations and improve EO IR payloads. Space-based cryocoolers tend to be costly items with low MRLs and TRLs. Currently, conventional space qualified cryocoolers do not exist that are compact, vibrationless and microscale. Traditional R&D shows small incremental improvements in size, weight, and power (SWAP) reductions. Optical refrigeration offers an innovative way to significantly reduce SWAP without large sacrifices in capability. All devices must be capable of 10 years operation in a space environment, including 300Krad total dose of radiation (ionizing and proton). Some notional system within which the improved component will operate must be described, including thermal stability across the array and stability over time. Increasing the thermal stability of the system improves the reliability and lifetime of the components, which are important for satellites. The nominal rejection sink of a usual payload is at 250-325 K and the minimal continuous duty lifetime is 10 years. Optical Refrigeration is based on anti-Stokes fluorescence in rare-earth doped solids. Recently temperatures down to 155K has been achieved in a ytterbium-doped crystal with a heat lift of >100 mW. Laser light can be delivered with a fiber to the cooling crystal which has shown to be able to deliver a high cooling power density (10 W/cm3). The compactness and solid-state aspect of these refrigerators make them suitable for cooling sensors in space applications where the lack of vibrations is critical. Furthermore, the low mass of the cooling head offers much desired agility in gimbal-mounted sensors. Achieving <100K is a significant challenge for optical cryocoolers, and requires an innovative approach.
| PHASE I: Efforts should concentrate on the development of the fundamental concepts for increased efficiency or reduced mass, jitter, or power input of space EO payloads by developing the concepts of a solid-state optical cryocooler that can approach 100 K with a cooling power exceeding 200 mW.
| PHASE II: Efforts should take the innovation of Phase I and design/implement the thermal link, cold finger, high power operation, and to demonstrate the innovation to specifications. Demonstration of the potential improvements in efficiency or mass reduction of space cryogenic coolers or space payloads should be included in the effort, but does not need to be optimized to flight levels.
| PHASE III | DUAL USE COMMERCIALIZATION:
Military Application: Transition into military systems working with spaced-based IR sensors is anticipated, particularly missile tracking, surveillance, and Operationally Responsive Space Flight Demos for EO IR payloads.
Commercial Application: Applications of this technology include NASA and commercial for space/airborne uses such as astronomy, weather & earth monitoring ,and ground uses such as superconducting electronics, and MRIs.
| References: | 1. Optical Refrigeration: Science and Applications of Laser Cooling of Solids By Richard Epstein, Mansoor Sheik-Bahae, ISBN 978 3 527 40876 4 2. D. V. Seletskiy, S. D. Melgaard, S. Bigotta, A. Di Lieto, M. Tonelli and M. Sheik-Bahae, "Laser Cooling of Solids to Cryogenic Temperatures," Nature Photonics 4, 161 - 164 (2010) 3. T. Roberts and F. Roush, USAF Cryogenic Thermal Management System Needs, Proceedings of the 2007 Cryogenic Engineering Conference 4. Davis, T. M., Reilly, J., and Tomlinson, B. J., USAF "Air Force Research Laboratory Cryocooler Technology Development," Cryocoolers 10, R. G. Ross, Jr., Ed., Plenum Press, New York (1999), pp. 21-32. |
| Keywords: | optical cooling; anti-Stokes; fluorescence; thermal management; cryogenics |
Questions and Answers: |
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