Coaxial Pulse Tube Refrigerator Research Articles

Investigation on the internal thermal link of pulse tube refrigerators

Within a pulse tube refrigerator (PTR) in coaxial configuration the pulse tube is located inside the regenerator matrix in axial direction. An internal thermal contact between these two main components of the coldfinger occurs. The experimental investigation of the direction and the quantity of transferred heat is in focus of this paper. Intermediate cooling of the regenerator by the corresponding part of its own pulse tube can improve the cooling performance of a PTR. Therefore, a well-adapted geometrical arrangement between the pulse tube and the regenerator is essential, considering the temperature distribution inside the coldfinger. We deduce design parameters to optimise the configuration of coaxial PTRs.

Factors influencing the lowest refrigerating temperature of the miniature co-axial pulse tube refrigerator

Experimental studies of the influencing factors on the lowest refrigerating temperature of a miniature co-axial pulse tube refrigerator have been carried out in this paper. The results show that with the decrease of the mole fraction of hydrogen in the hydrogen-helium mixture, the lowest refrigerating temperature decreases, and when the mole fraction of hydrogen is below 20%, the lowest refrigerating temperature is close to that obtained using pure helium. In addition, it is also found that the optimum frequency of the compressor is about 16.7 Hz for different hydrogen-helium mixtures. When the charge pressure of the compressor increases, the lowest refrigerating temperature decreases; however, the decreasing trend gradually slows down with the increase of the charge pressure. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(4): 219–225, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20065

A practical microwave subsystem of HTS filter integrated with coaxial pulse tube refrigerator

The pulse tube refrigerator is a competitive new technology for cooling HTS microwave devices because it involves no moving parts at low temperature. A new Chebyshev type 8-pole band-pass filter with bandwidth about 1GHz at 5.6 GHz was designed and fabricated on a 20 × 20 × 0.5 mm LaAlO 3 substrate. Integrated with a coaxial pulse tube refrigerator, the filter shows satisfactory performance with low insertion loss (less than 0.6dB) and high out band rejection (better than 60 dB), which demonstrated successfully the potential application of the integrated device and the refrigerator as a practical HTS sub-system.

Experimental analysis of the multi-bypass principle in pulse tube refrigerators

This paper describes the structural characteristics and the mechanical performance of a co-axial pulse tube refrigerator with a multi-bypass. Some experimental results and an experimental analysis of the multi-bypass method are also given. The minimum attainable temperature at the cold end of a co-axial pulse tube refrigerator with multi-bypass is 33 K at a vacuum of 1 × 10 −4 torr. This shows that the performance of a pulse tube refrigerator is comparable to that of a Stirling refrigerator. Moreover, pulse tube systems would probably be more extensively used than Stirling refrigerators because of their advantages in terms of structural simplicity and mechanical reliability.

Development of a liquid nitrogen precooled co-axial pulse tube refrigerator

This paper describes the testing of a liquid nitrogen precooled co-axial pulse tube refrigerator. It mainly considers the influence of opening the orifice and double-inlet valve, and the effect of changing the average pressure, frequency and system vacuum upon the lowest temperature achieved. The experimental refrigerator reached a lowest temperature of 20 K with no load. It has great potential for use in certain practical applications.