Haizheng Dang

High efficiency pulse tube cryocoolers for aerospace applications

This paper reviews the recent advances in Stirling-type pulse tube cryocoolers for aerospace applications in the authors group. Due to the special environment featuring the limited power supply and adverse rejection condition, high cooler efficiencies are emphasized and thus the approaches to realize them are stressed. The cold fingers involve three geometries, and designs and optimizations on key dimensional parameters of coaxial and in-line ones for given compressors are discussed and compared. The high performance moving-coil linear compressors are studied, and the optimizations on linear motor and flexure springs are briefly reviewed as examples of studies on the key compressor technologies. The mature single-stage coolers cover 25-200 K with the capacities varying from milliwatt levels to over 30 W, and the high efficiencies at typical temperatures such as 40 K, 60 K, 80 K and 95 K are presented. The two-stage arrangement is becoming another trend to achieve cooling below 25 K and also to simultaneo...

High frequency coaxial pulse tube cryocoolers for cooling infrared focal plane arrays

A survey is made about the development of high frequency coaxial PTCs. The coolers cover from 30 K to 200 K and the cooling power levels from hundreds of milliwatts to 10s W. Tests suggest that they have the potential to provide appropriate cooling for HgCdTe-based infrared focal plane arrays from near visible down to very long wave infrared region. The paper also discusses the efforts to realize space qualified cryocooler technologies.

Development of high frequency pulse tube cryocoolers for space applications

This paper reviews recent advances in high frequency pulse tube cryocoolers developed in SITP/CAS to provide high reliability, low-noise and long life cooling for potential space applications. The advances in understanding the cooler mechanism and minimizing irreversible losses in various components are described, which have made a great contribution to the improved efficiencies. At present, the operating temperatures cover from 30 K to 200 K and the cooling capacities vary from hundreds of milliwatts to over 20 W to meet a variety of requirements. Some typical cryocooler development programs are introduced and a brief overview of the updated data package is presented. The proposed applications, design approaches, research advances, the major problems and the efforts to overcome them are described.

Development of a Miniature Coaxial Pulse Tube Cryocooler for a Space-Borne Infrared Detector System

A single-stage miniature coaxial pulse tube cryocooler prototype is developed to provide reliable low-noise cooling for an infrared detector system to be equipped in the future space mission. The challenging work is the exacting requirement on its dimensions due to the given miniature Dewar. The limited dimensions result in the insufficiency of the phaseshifting ability of the system when inertance tubes alone are employed. A larger filling pressure of 3.5 Mpa and higher operating frequency up to 70 Hz are adopted to increase the energy density, which compensates for the decrease in working gas volume due to the miniature structure, and realize a fast cool down process. A 1.5 kg dual opposed linear compressor based on flexure bearing and moving magnet technology is used to realize light weight, high efficiency and low contamination. The design and optimization are based on the theoretical CFD model developed by the analyses of thermodynamic behaviors of gas parcels in the oscillating flow. This paper describes the design approach and trade-offs. The cooler performance and characteristics are presented.

Advances in single- and multi-stage Stirling-type pulse tube cryocoolers for space applications in NLIP/SITP/CAS

This paper presents a review of recent advances in single- and multi-stage Stirling-type pulse tube cryocoolers (SPTCs) for space applications developed at the National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (NLIP/SITP/CAS). A variety of single-stage SPTCs operating at 25–150 K have been developed, including several mid-sized ones operating at 80–110 K. Significant progress has been achieved in coolers operating at 30–40 K which use common stainless steel meshes as regenerator matrices. Another important advance is the micro SPTCs with an overall mass of 300–800 g operating at high frequencies varying from 100 Hz to 400 Hz. The main purpose of developing two-stage SPTCs is to simultaneously acquire cooling capacities at both stages, obviating the need for auxiliary precooling in various applications. The three-stage SPTCs are developed mainly for applications at around 10 K, which are also used for precooling the J-T coolers to achieve further lower temperatures. The four-stage SPTCs are developed to directly achieve the liquid helium temperature for cooling space low-Tc superconducting devices and for the deep space exploration as well. Several typical development programs are described and an overview of the cooler performances is presented.

Development of a 2.0W at 60K Single-stage Coaxial Pulse Tube Cryocooler for Long Wave Infrared Focal Plane Array Applications

A 2.0W@60K single-stage coaxial pulse tube cryocooler has been developed to provide reliable low-vibration cooling for the space-borne long wave infrared focal plane array. The coaxial configuration result in a compact system and the inertance tube together with a gas reservoir serves as the only phase-shifting to realize a highly reliable system. The inertance tube consists of two parts with different inner diameter and length to obtain the desirable phase relationship. Both cold tip and warm flange integrated with fine slit heat exchanges fabricated with electro discharge machining technology to enhance heat exchange performance. A split Oxford-type linear compressor with dual-opposed piston configuration is connected to the cold finger with a 30 cm flexible metallic tube. The overall weight without control electronics is below 8 kg. The preliminary experiments show that a no-load temperature of 46 K and a cooling power of 2 W at 60 K with 104 W of input power at 300K reject temperature have been achieved.

Development of space Stirling and pulse tube cryocoolers in Shanghai Institute Technical Physics, Chinese Academy of Sciences

This paper briefly reviews the development of space Stirling and pulse tube cryocoolers in Shanghai Institute Technical Physics, Chinese Academy of Sciences (SITP/CAS). The status of both types of coolers is outlined, including those currently undergoing performance optimization, qualification investigation, or characterization and endurance evaluation. The approaches for vibration control and the efforts to increase reliability are also presented. The purpose is to present a brief overview of the data package of both types of coolers developed and under developing in SITP/CAS, and also demonstrates our efforts to enable space qualified cryogenic technologies in China.

Interference characterization of Stirling-type nonmagnetic and nonmetallic pulse tube cryocoolers for high-Tc SQUIDs operation

Publisher Summary This chapter describes the design and optimization of Stirling-type nonmagnetic and nonmetallic pulse tube cryocoolers (NNPTCs). These cryocoolers are developed to achieve portable low-noise cryogen-free cooling systems for continuous high-Tc SQUIDs operation and realize their direct coupling with the sensors. The optimizations of the cooler geometry and working parameters have been carried out. Stirling-type PTCs have advantages over their GM-type counterparts in terms of compactness, flexibility, portability and low vibration, due to the much smaller volume and much lighter weight (a reduction in volume or weight by a factor of above 5–10) and the absence of rotary valves, which adds the possibility of the direct coupling. An evaluation of the typical cooling performance and interference characterization of the new-type pulse tube coolers are also presented. A typical cooling power of 130mW at 80K for 70 W of input power has been achieved, which can meet the basic cooling requirements of the high-Tc SQUIDs. Preliminary results indicate the interference characteristics of the system can meet the basic noise requirements of the sensors. A disadvantage is that the performances of the Stirling-type NNPTCs are much poorer than those of their conventional metallic counterparts, and in practical applications, larger cooling power and lower working temperatures are usually desired. So the performance optimization of the coolers is underway.

Theoretical and experimental investigations on the dynamic and thermodynamic characteristics of the linear compressor for the pulse tube cryocooler

Theoretical and experimental investigations on the dynamic and thermodynamic characteristics of a linear compressor incorporating the thermodynamic characteristics of the inertance tube pulse tube cold finger have been made. Both the compressor and cold finger are assumed as a one-dimensional thermodynamic model. The governing equations of the thermodynamic characteristics of the working gas are summarized, and the effects of the cooling performance on the working gas in the compression space are discussed. Based on the analysis of the working gas, the governing equations of the dynamic and thermodynamic characteristics of the compressor are deduced, and then the principles of achieving the optimal performance of the compressor are discussed in detail. Systematic experimental investigations are conducted on a developed moving-coil linear compressor which drives a pulse tube cold finger, which indicate the general agreement with the simulated results, and thus verify the rationality of the theoretical model and analyses.

Theoretical and experimental investigations on the match between pulse tube cold fingers and linear compressors

The match between the cold finger and the linear compressor of the Stirling-type pulse tube cryocooler plays a vital role in optimizing the compressor efficiency and in improving the cold finger cooling performance. To reveal the match mechanism between the linear compressor and pulse tube cold finger (PTCF), detailed analyses have been made to understand the interactions between them. Based on the theoretical investigations, both of the design method of the PTCF to match the given linear compressor and a reverse method of the linear compressor to match the given PTCF have been proposed. In order to verify the validity of these theories and methods, actual PTCF and linear compressor are developed to match the existing linear compressor and PTCF, respectively. The experimental results show good agreements with the simulated ones.