By Thom Davis, B. J. Tomlinson, Jim Ledbetter (auth.), R. G. Ross Jr. (eds.)
Over the final years we now have witnessed a continuation within the step forward shift towards pulse tube cryocoolers for long-life, high-reliability cryocooler functions. One type of pulse tubes that has reached adulthood is known as "Stirling kind" simply because they're in response to the linear Oxford Stirling-cooler kind compressor; they often supply cooling within the 30 to a hundred okay temperature diversity and function at frequencies from 30 to 60 Hz. the opposite kind of pulse tube cooler making nice advances is the so-called "Gifford-McMahon kind. " Pulse tube coolers of this sort use a G-M variety compressor and reduce frequency operation to accomplish temperatures within the 2 to ten ok temperature diversity. approximately a 3rd of this complaints covers those new advancements within the pulse tube area. Complementing the paintings on low-temperature pulse tubes is vast persisted growth on infrequent earth regenerator fabrics and Gifford-McMahon coolers. those applied sciences proceed to make nice growth in establishing up the two - four okay marketplace. additionally within the advertisement area, endured curiosity is being proven within the improvement of long-life, reasonably cheap cryocoolers for the rising extreme temperature superconductor electronics industry, rather the cellular phone base-station marketplace. At greater temperature degrees, closed-cycle J-T or throttle-cycle fridges are benefiting from combined refrigerant gases, spearheaded within the former USSR, to accomplish reasonably cheap cr- cooler platforms within the sixty five - eighty okay temperature range.
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Extra info for Cryocoolers 11
2 W refrigeration at 35 K and 3 W refrigeration at 60 K. This Oxford-class unit employs three finger tangential flexures in the compressor module. These flexures have been shown to provide smoother, lower vibration piston motion than previously obtained with conventional three finger spiral flexures. Acceptance Tests validated the required performance capabilities and Qualification Tests validated the cooler for flight. Acceptance Tests included performance mapping at rejection temperatures from 275 K to 325 K, residual vibration measurements for each module, temperature stability under various conditions, cold tip motion, cold tip side load capacity.
Raytheon PSC. The Raytheon PSC is a split-Stirling cryocooler designed to lift 2W @ 60K. This cryocooler is the latest design from Raytheon and is directly related to the older Raytheon SSC II currently under endurance at AFRL. 2W @ 35K. After characterization, the PSC entered its endurance evaluation, but was shut down temporarily due to an electronics problem in the control rack. With the problem was solved, the cooler was moved to a 24” thermal vacuum chamber and is continuing with endurance evaluation.
It was determined that the PSC, without design modification, outperformed both in efficiency and cooling loads, existing cryocoolers specifically designed to perform in the 35K region. At 35K, the PSC was able to cool loads over one watt with thermo-mechanical efficiencies under 90w/w from a reject temperature of 300K. In addition, the system was able to deliver up to 3W at 60K, a 50% increase over the 2W cooling load requirement. COMMENTS ON IPT PROGRAM MANAGEMENT The PSC Integrated Product Team (IPT), including the government Project Officer and key Raytheon personnel, encountered and solved a number of problems during the course of the program.
Cryocoolers 11 by Thom Davis, B. J. Tomlinson, Jim Ledbetter (auth.), R. G. Ross Jr. (eds.)