THE BALLISTIC MISSILE DEFENSE ORGANIZATION CRYOGENIC COOLING TECHNOLOGY DEVELOPMENT FOR SPACE-BASED INFRARED SYSTEM LOW

摘要

The Air Force Research Laboratory (AFRL) and its predecessors, Phillips Laboratory and the Air Force Space Technology Center, has been the primary agent of the Ballistic Missile Defense Organization (BMDO) for the development of low capacity cryogenic refrigerators and integration technologies for space applications since the mid 1980s. These cryocooler development programs concentrated on addressing the negative impacts of mechanical refrigerators on optical space systems: induced line of sight vibration, longevity, power consumption, and mass. The initial focus of development efforts was on relatively large capacity machines to support cooling requirements for the Space Surveillance and Tracking System (SSTS). The protoflight Cryocooler program produced two three-stage 10K cryocoolers (Contractors: Air Research and Arthur D. Little) for cooling of the long wave silicon focal plane arrays. Both of these programs were terminated in the final stages of assembly as a result of the cancellation of SSTS in 1989. An additional program aimed at 10K performance was jointly funded with the Brilliant Eyes program office (successor to SSTS) and focused on sorption technology. Primarily developed by NASA's Jet Propulsion Laboratory and Aerojet, this program culminated with the BESTCE Shuttle flight experiment in 1995. While overall performance was adequate, the sorption cryocooler was considered too large for current small satellite payloads. The Standard Spacecraft Cryocooler program (SSC) initiated in 1990 marked a change in emphasis from relatively large machines to more compact and efficient cryocoolers aimed at meeting cooling needs in the range from 60K to 150K for mid-wave infrared (MWIR) applications. Using Oxford Stirling cycle technology developed primarily in the United Kingdom, these machines utilized linear drive motors and tight clearance seal non-contacting piston shafts. The pulse tube cryocooler, a variation of this technology, replaces the actively moving expander piston with a non-moving regenerator and pulse tube. AFRL has also pursued alternate cryocooler concepts including reverse Brayton cycle designs. The principal technological challenge of these simple Brayton machines is accurately micro-machining the components (impellers, shafts, motor magnets, etc). For extremely low temperature cooling (～10K), variants using Joule-Thomson combinations and improved Stirling and pulse tube designs are being considered.