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Proceedings Paper

Development of miniature, high frequency pulse tube cryocoolers
Author(s): Ray Radebaugh; Isaac Garaway; Alexander M. Veprik
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Paper Abstract

Because acoustic power density is proportional to frequency, the size of pulse tube cryocoolers for a given refrigeration power can be reduced by operating them at higher frequencies. A frequency of about 60 Hz had been considered the maximum frequency that could be used while maintaining high efficiency. Recently, we have shown through modeling that by decreasing the volume and hydraulic diameter of the regenerator and increasing the average pressure, it is possible to maintain high efficiency even for frequencies of several hundred hertz. Subsequent experimental results have demonstrated high efficiencies for frequencies of 100 to 140 Hz. The very high power density achieved at higher pressures and higher frequencies leads to very short cooldown times and very compact devices. The use of even higher frequencies requires the development of special compressors designed for such conditions and the development of regenerator matrices with hydraulic diameters less than about 30 Μm. To demonstrate the advantages of higher frequency operation, we discuss here the development of a miniature pulse tube cryocooler designed to operate at 80 K with a frequency of 150 Hz and an average pressure of 5.0 MPa. The regenerator diameter and length are 4.4 mm and 27 mm, respectively. The lowest temperature achieved to date has been 97 K, but a net refrigeration power of 530 mW was achieved at 120 K. Acoustic mismatches with existing compressors significantly limit the efficiency, but necessary modifications to improve the acoustic impedance match between the compressor and the cold head are discussed briefly.

Paper Details

Date Published: 3 May 2010
PDF: 14 pages
Proc. SPIE 7660, Infrared Technology and Applications XXXVI, 76602J (3 May 2010); doi: 10.1117/12.852766
Show Author Affiliations
Ray Radebaugh, National Institute of Science and Technology (United States)
Isaac Garaway, National Institute of Science and Technology (United States)
Alexander M. Veprik, RICOR, Cryogenic and Vacuum Systems (Israel)

Published in SPIE Proceedings Vol. 7660:
Infrared Technology and Applications XXXVI
Bjørn F. Andresen; Gabor F. Fulop; Paul R. Norton, Editor(s)

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