Stage Pulse Tube Refrigerator Research Articles

Experimental investigation of the connecting tube effect on a step displacer type two stage pulse tube refrigerator

Using the step displacer in two stage pulse tube refrigerator has already been proved as a sufficient way to improve the efficiency. In this article, an experimental setup has been manufactured. A no-load temperature of 16.9 K is achieved with a step displacer type gas-coupled pulse tube refrigerator filled with stainless steel mesh. The influence of the connecting tube between pulse tube hot end and displacer on the performance of the refrigerator is investigated. The experimental results show that the phase shifting ability can be adjusted by the connecting tube. The performance of the refrigerator can be optimized by this method. For different rod diameters, there is an optimum connecting tube ratio to get the lowest temperature.

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English

CFD Simulation to Optimise Single Stage Pulse Tube Refrigerator Temperature Below 6oK

An optimize result of the single stage iterance tube pulse tube refrigerator (ITPTR) has been found by the use of a computational fluid dynamic (CFD) solution method. A well CFD solution software FLUENT is used for solution purpose. A number of case has been solved by changing the pulse tube length by taking diameter constant out of which it is found that a length of about 125mm at which the minimum temperature is achieved at cold heat exchanger end of 58K. The variation in any parameter of ITPTR will affect the cooling temperature that may be the length or diameter of pulse tube or inertance tube or change in operating frequency but it is essential to achieve lower temperature than till date achieved by same method. So for optimization purpose we take the length of pulse tube length as the varying Para-meter and the operating frequency 34Hz, pulse tube diameter 5mm remains constant. To get an optimum parameter experimentally is a very tedious for iterance tube pulse tube refrigerator job so the CFD approach gives a better solution which is the main purpose of the present work.

Aligned nuclear targets for the test of time reversal invariance

The new aligned nuclear targets are proposed for investigation of time reversal invariance violation (TRIV) in the neutron-nuclei interactions with the use of five-fold correlation. The nuclei121Sb,123Sb and127I can be aligned in these targets by brute force method at 20 mK. The construction of127I single crystal target is considered with the use of dilution refrigerator that is precooled by two stage pulse-tube refrigerator without any cryoliquids. The use of above targets at new neutron spallation sources (SNS, USA and JSNS, Japan) will provide a way of TRIV observation or allow to decrease the present limit on intensity of parity conserving time violating interation by two orders of magnitude.

Thermodynamic analysis of active valve pulse tube refrigerators

This paper presents a detailed thermodynamic analysis of the working process of an active valve pulse tube refrigerator which is introduced to enhance the performance of a single stage pulse tube refrigerator. With the aid of several simplifying assumptions, the theoretical refrigeration power and coefficient of performance of this kind of refrigerator are obtained. Simulation results illustrate that the values of two intermediate pressures play a significant role in the system performance.

Two stage pulse tube refrigerator with double rotary valves

We have constructed a two stage pulse tube refrigerator equipped with two rotaryvalves. The first stage regenerator was made of stainless steel tube 39mm OD, 0.5mm thickness and 180mm long packed 1735 stainless steel screens of 200 mesh and the second stage regenerator was made of stainless steel tube 18mm OD, 0.3mm thickness and 250mm long packed with stainless steel screen of 250 mesh and lead shots of about 0.3 mm diameter. The performance was investigated by changing the ratio of the stainless steel mesh and lead shots of the second regenerator and the volumes of first and second pulse tubes. The second stage cold end reached below 20K.

Multi-staged pulse tube refrigerator for superconducting magnet applications

This paper describes the experimental results of the pulse tube refrigeratorwhich could be used for the cooling system of the superconducting magnet. In 1993, we developed three-staged pulse tube refrigerator which has a cooling capacity of 100 mW at 4.8 K and the minimum attainable temperature of 3.6 K, and single stage pulse tube refrigerator which has a cooling capacity of 15 W at 80 K and the minimum attainable temperature of 22 K. These results indicate the possibility of the NbTi magnet cooling system combined with a pulse tube refrigerator which has no moving parts at the low temperature region. Design parameters and some preliminary test results are also given.