The MMR (Micro Miniature Refrigerator) is a novel Joule-Thomson cryocooler manufactured by micro-machining technology, its axial length is significantly shorter than the traditional Joule-Thomson cryocoolers that are used in infrared detectors. So MMRs can greatly reduce the size of infrared detectors once they are successfully integrated. To study the working mechanism of MMRs a micro-channel flow calculation model is established considering the gas compressibility, the Joule-Thomson effect at the throttling section and the distributed Joule-Thomson effect along the micro channels and the calculation model is verified with experiments. The characteristics of heat transfer, micro-channel distribution and heat losses are further investigated, leading the model to describe the working condition of the MMR more correctly. The temperature and pressure distribution in the micro channels and the theoretical cooling performance of the MMR is thus obtained, and a set of MMR geometry parameters with superior theoretical cooling performance are acquired. Furthermore, a MMR prototype is fabricated, and a testing platform is built and the cooling performance of the prototype is experimentally studied. The experimental results agree well with the prediction of the calculation model. The MMR prototype achieves 110K and 119K cooling temperature under 10MPa N2 and Ar working condition, the cooling power reaches 231mW and 479mW, and the cool down time is 250s and 70s respectively. As a result, the cooling performance of the MMR prototype can meet the cool down requirement of infrared detectors, providing a new approach to infrared detectors’ miniaturization.

The vibration of a single-piston linear Stirling Cryocooler caused by the compressor operation seriously affects the component performance and imaging quality of the infrared detector, so in terms of vibration abatement, the use of a vibration absorber has become an important way of vibration damping. While during using the vibration absorber, the damping variation is an important factor affecting the vibration damping performance. Hence, through the experimental analysis of the damping variation of the vibration absorber, it is identified in this paper that the main reason for the damping variation is the variation of mass and amplitude of the vibration absorber, which affects the deformation of the plate spring and the internal friction energy dissipation of the material. It is discovered in the experiment that at the same amplitude, the damping variation is the most stable when the mass of the vibration absorber is 28.6g~36.4g and the amplitude is 1.6~2.1mm. In the end, a vibration-damping experiment is also carried out for the compressor using a vibration absorber with a mass of 33.1g. When the compressor operates at a working frequency of 75Hz and an input power of 6W, its vibration acceleration can be decreased from 42.274m/s2 before vibration damping to 3.047m/s2 .

当前,对于吸振器和单活塞线性斯特林制冷机振动系统的研究,几乎都是在已知制冷机进行某种固定安装方式的正定模型上进行的.而这种正定方法由于缺乏对制冷机和吸振器系统固有频率的分析,当改变系统的安装方式后,可能会产生共振并减小吸振器的减振效果.基于此,本文将对制冷机和吸振器振动系统在未进行任何安装时的半正定模型进行理论分析,并通过悬挂测试法对制冷机适配吸振器前后进行振动实验.由此得到了系统在半正定模型下的理论固有频率值为78.6Hz.而通过实验可发现,受吸振器实际加工和装配的影响,系统的固有频率随吸其刚度的增大而增大,其增大的范围在78.1～80.8 Hz之间.

The attainment and maintenance of a low temperature environment is essential for aerospace cryogenic detectors to achieve their required performance. Developing cryocoolers with features of high efficiency, compact structure, and long lifetime is the main challenge for cryogenic detector cooling. In this paper, a high efficiency thermally-coupled two-stage Stirling type pulse tube cryocooler working at 35 K for HgCdTe long wave infrared detector cooling is designed and tested. The thermally-coupled type avoids gas distribution at cold side which minimizes the inter-stage influence. The whole cryocooler is driven by one linear compressor which enables compact structure. The influence of operation frequency and mean pressure is studied by numerical calculation and experiments to determine the optimum operation condition. Acoustic impedance characteristics of both stages and the whole cold finger are also analyzed by comparing performance of cryocooler with different frequency, mean pressure and structure dimensions. The distributions of acoustic power and phase angle are presented to study the relation between impedance characteristic and the cooling performance. Impedance match between compressor and cold finger is also discussed by analyzing the efficiency of the linear compressor and the performance of cryocooler with different pulse tubes. Under optimum impedance match and operation condition of a working frequency of 39.2 Hz and a mean pressure of 2.45 MPa, the cryocooler provides a cooling power of 1 W at 35.1 K with an input electrical power of 150 W, which indicates a relative Carnot efficiency of 5%. This is a rather high efficiency for developed Stirling type multi-stage pulse tube cryocooler working at 35 K with only inertance tubes as phase shifter. The development of this cryocooler lays a solid base for the further optimization to realize a competitive candidate for aerospace cooling requirements.

微机电系统MEMS(micro-electro-mechanical system)是一种集合了微电子与机械工程技术的新型高科技装置,其制造工艺可以进行最小至纳米尺度的加工以及高度集成化的微型制造.其产品微小体积、高度集成化以及高性能高产热的特性也决定了其需要匹配相应的制冷解决方案,本文重点阐述了基于MEMS制造工艺并同时应用于MEMS产品的微型制冷器的工作原理、性能及发展趋势.分别分析了微型半导体制冷器以及微型节流制冷器各自的优势和不足,对微型制冷器的未来发展提出了建议.

The SC100H linear Stirling cryocooler is designed by Kunming Institute of Physics. The characteristics of the magnetic circuit of the moving magnet linear oscillation motor used in SC100H was analyzed by the theoretical and experimental methods. In this study, a theoretical model of the motor was established, and its structure was simplified for easy analysis and calculation. Using the equivalent circuit methods and principle of electromechanical energy conversion, the relationship between the thrust characteristic and relative position of the mover in the motor was analyzed. The thrust characteristics of the motor at different input currents were tested by a tension test system. The results were consistent with that predicted from the theoretical analysis. Taken together, this study provided a good basis for the design and optimization for the structure and operation parameters of the motor.

线性压缩机目前是长寿命斯特林制冷机和高温斯特林制冷机常用的压缩机.本文首先分析了阻尼系数在压缩机运行过程中对压缩机的影响,然后对线性压缩机阻尼系数测试方法进行了理论分析,最后对昆明物理研究所线性压缩机的阻尼系数进行了测试分析.通过理论分析给出了线性压缩机的阻尼计算方法,并搭建真空实验平台测试出压缩机的阻尼系数.对昆明物理研究所SCI09H制冷机的线性压缩机和SCI15H制冷机的线性压缩机进行了阻尼测试,测试结果表明不同线性压缩机的阻尼系数并不完全相同.

Due to the advantages of low vibration and long MTTF,Free Piston Stirling Cooler(FPSC)can be uesed to cool down the infrared detectors. With the development of the High Operation Temperature detector(HOT detector),re-duction of size,weight,power along with higher performance and lower price is needed for the stirling cooler,which can be defined as micor-miniature stirling cooler. In this paper,we summarized the development of the micro-miniature FPSC at home and abroad in recent ten years,and introduced it's design balance. One novel micro-miniature FPSC prototype de-veloped by Kunming Institute of Physics is also shown in this paper.

This paper is based on the SC100H linear Stirling Cryocooler which has been designed by Kunming Institute of Physics.The theoretical and experimental study has been used in analyzing the magnetic circuit characteristics of the moving magnet linear oscillation motor.In this paper,a theoretical model of the motor is established,and the structure of the model is simplified in order to analyze and calculate the model.By using the equivalent circuit methods and the principle of electromechanical energy conversion,the relationship between the thrust characteristic of the motor and the relative position of the rotor is analyzed.We also build a test experiment rig by using the force testing system and the relationship between the thrust characteristic of the motor and the input current were tested.The test results are consistent with the theoretical value very well,which provides a design basis for the design and optimization of structure parameters and operation parameters of the motor.

With no moving parts at cold head, the pulse tube cryocooler has merits of high reliability, long life and low vibration, which are evident advantages in space use. Basic structure, numerical simulation and experiment performance of a micro pulse tube cryocooler(C391) are introduced in this paper. The compressor is driven by a moving-magnet linear motor, supported by flexure bearings and clearance seal technology, and the expander is with coaxial structure between regenerator and pulse tube, which is very convenient for coupling between cold head and infrared devices. The phasor shift characteristics of C391 is simulated using SAGE software, and it is verified by experiments.

As the key component of the linear Stirling cryocooler,the regenerator plays a vital role on the thermal performance.Based on the effect of the filled metal meshes on regenerators' thermal performance and the simulation results of REGEN3.3,three typical multi-metal-mesh filled regenerators were built and tested,which are assembled in linear Stirling cryocooler.The experimental results show that the regenerator,which have been multi-metal-mesh filled in a right way,can make a great thermal performance improvement of linear Stirling cryocooler.Finally,the cooling rate of the crycooler was improved by 14％,and the efficiency of cryocooler was improved by 37.5％.

Basic structure,numerical simulation and experiment performance of a high capacity singlestage coaxial pulse tube cryocooler(C392) were introduced.The compressor is driven by a Redlich type moving-magnet linear motor,supported by flexure bearings and using clearance seal technology,the motor efficiency is over 83％ at 80 K.Regenerator and pulse tube in expander are coaxial,which makes the coupling between cold head and infrared devices convenient.The cooler performance and phasor shift characteristics of C392 are simulated by numerical simulation software,and it is verified by experiment.The operating frequency and cooling performance are researched.At 80 K,the typical cooling power of 10 W can be achieved with 210.3 W input electric power,and the relative Carnot efficiency is 12.66％,when the cooler operates with the frequency of 62 Hz.And the weight of cooler is less than 5.5 kg.

The moving magnet linear compressors are very popular in the tactical miniature stirling cryocoolers. The magnetic circuit of LFC3600 moving magnet linear compressor, manufactured by Kunming institute of Physics, was studied in this study. Three methods of the analysis theory, numerical calculation and experiment study were applied in the analysis process. The calculated formula of magnetic reluctance and magnetomotive force were given in theoretical analysis model. The magnetic flux density and magnetic flux line were analyzed in numerical analysis model. A testing method was designed to test the magnetic flux density of the linear compressor. When the piston of the motor was in the equilibrium position, the value of the magnetic flux density was at the maximum of 0.27T. The results were almost equal to the ones from numerical analysis.

The vibrator in pneumatic expander of split-stirling cryocooler was analyzed and verified. With pneumatic rod area increases, vibrator's phase angle decreases, while stroke increases. The cooling capacity of Stepped-rod type was compared with direct-connected type's. The stepped-rod area rate will affect the matching of the expander to the compressor. The pressure ratio, phase angle and amplitude were considered to determine the area of the stepped-rod. The stepped-rod type expander’s wide frequency adapt characteristics is also analyzed.

Changes of two dynamical factors would be induced when Matching Pneumatic Expander to the Linear Compressor, those are displacer’s natural frequency and motion damp. Experimental Study about the influence of the two dynamical factors on the cooling performance was made(the charging pressure is 1.8MPa ). Some conclusions were acquired: compressor’s resonant frequency was slightly affected by the displacer’s natural frequency and motion damp, so the effect could be ignored. The optimum ratio value of the operating frequency to the displacer’s natural frequency is about 0.7. Further more, the optimum ratio value reduces with the increment of the motion damp.

This paper analyzes resonant frequency of the moving magnet linear compressor of Stirling cryocooler. The CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) are used for the analysis of resonant frequency with FLUENT 6.2 and ANSYS 11.0 and an experiment is designed for testing the resonant frequency of moving magnet linear compressor. Results from simulations and experiments showed that the resonant frequency of the moving magnet linear compressors is affected by the machine spring, the gas spring, the magnet spring, and the mass of moving assembly, while the resonant frequency of the moving coil linear compressors is only affected by the machine spring, the gas spring, and the mass of moving assembly.

The influence of the displacer resonant frequency on the cooling performance was studied experimentally. Three conclusions were acquired. Firstly,with the increment of the displacer's resonant frequency,the compressor's resonant frequency decreases. Secondly,the cooling performance is strongly enhanced when charging pressure is 1.8 MPa and the ratio value of the working frequency to the displacer's resonant frequency is within 0.73～0.75. Lastly,for the enhancement of cooling performance,not only must the cooler work at the resonant frequency of the compressor,but also the ratio of the working frequency to the displacer's resonant frequency should be adjusted to the optimized value.

Moving magnet linear compressors are very popular compressor in tactical miniature stirling cryocoolers.This paper studied LFC3600 moving magnet linear compressor manufactured by Kunming institute of physics.The analysis theory,numerical calculation and experiment research are used in the analysis.The calculated formula of magnetic reluctance and magnetomotive force are given in theoretical analysis model.The magnetic flux density and magnetic flux line are analyzed in numerical analysis model.A novel testing method is designed to test magnetic flux density of linear compressor,and results are almost equal to numerical results.

Moving magnet linear stirling cryocoolers are very popular tactical miniature ones.This paper studied the SCI15H moving magnet linear stirling cryocooler manufactured by Kunming institute of physics.The FEM and CFD methods were used in analysis models.Inner helium flow and cooling power of stirling cryocooler were calculated in thermodynamics analysis model,magnetic flux density was calculated in magnetic circuit analysis model,the spring stress and stiffness were calculated in spring analysis model.

The integration Stirling cooler was analysed by numerical methods. The mathematical model is constructed according to a real cooler, and the flow resistance is added in the computational model. The cooler was then tested. The whole cooler is divided into 13 controlling volumes, and the mass equation, momentum equation, and energy equation were established for each volume. The computation program was written in Visual C++ and MATLAB. These basal equations were solved by iteration. Comparing the calculating pressure and power data with the testing data, the model we constructed is more close to real Stirling cooler than other computational ones. The program has been used in new Stirling cooler design.