SUMMARY

Pulse tube refrigerators (PTR) are robust, efficient cryocoolers capable of providing refrigeration at cryogenic temperatures. They are often employed in space applications for cooling of high performance electronics. Miniaturizing these refrigerators has been a subject of intense research interest because of the benefits of minimizing their size and weight for airborne operation and because miniature coolers would be an enabling technology for other applications. Despite this effort, the extent of possible PTR miniaturization is still uncertain. Several phenomena expected to limit PTR performance as their scale is reduced have been identified, but some of their effects have not been quantified and many are not included in the models commonly used for analyzing conventional scale Stirling machines and PTRs. Certainly, further progress on miniature PTRs will require directly applicable tools for their design and analysis which represent all of the relevant phenomena. The proposed investigation seeks to address this need through the development of suitable system and component level models for miniature PTRs, including experimental measurement of necessary closure relations. These models will then be used to quantify the effects of several phenomena expected to affect miniaturization and to estimate the minimum size threshold below which further miniaturization may be impractical.