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As the demand for compact pulse tube cryocoolers in space applications continues to grow, the lightweight design has become crucial. The phase shifter occupies a significant portion of the system’s weight. To optimize this issue, a Sage model was established to investigate the impact of different combinations of inertance tubes on the performance of cryocoolers. An experimental system was set up to validate the simulation results. The experimental data show excellent agreement with simulations and indicate that using a single-stage inertance tube can reduce the weight of the cryocooler with minimal performance compromise.

The mechanical Joule-Thomson (JT) refrigerator operating in 2 K-class or 4 K-class temperature ranges serve as crucial equipment for space astronomical observation and deep space exploration. Current typical space-borne JT cryocoolers face multiple technical challenges due to their compressor operation at ambient temperatures, including excessive pressure ratio requirements, increased compressor stages, enlarged system volume/weight/power consumption, as well as complex configurations with multiple inefficient heat exchanger stages. This study analyzed the enthalpy of a typical helium throttling refrigeration cycle and found that there is an optimal pressure ratio for the throttling refrigeration. A quantitative comparison was made between operating at the optimal pressure ratio and operating at a typical 20 times pressure ratio, resulting in a 66 % increase in refrigeration capacity and a 28.1 % decrease in power consumption. This study innovatively proposes a novel solution by implementing cryogenic operation of the driver assembly and establishing a throttling refrigeration cycle with working fluid in sub-20 K temperature range. This approach fundamentally provides new possibilities for pressure ratio reduction in cryocooler systems.

With the advancement of deep cryogenic detection technology, spacecraft are required to operate at a background temperature of 100 K or lower, necessitating the use of pulse tube cryocooler as a critical support component. Traditionally, the compressor and hot end heat exchanger of pulse tube cryocooler function at an ambient temperature of 300 K. Multi-stage pulse tube cryocoolers typically require precooling to a temperature range of 80 K to 100 K before the second stage can commence operation. The transient regenerator serves as the thermal buffer between the ambient temperature compressor and the secondary pulse, leading to significant PV power losses and reduced cryocooler efficiency. Additionally, two-stage pulse tube cryocoolers often exhibit low operating frequencies, large volumes and weights, and high launch costs. This paper presents the design of a micro single-stage coaxial pulse tube cryocooler capable of direct operation in the 80 K temperature range. The cryocooler is powered by liquid nitrogen precooling and a linear compressor, with a total mass of 2.6 kg. It employs inertance tube and gas reservoir as phase shifters. The cold finger has a diameter of 14 mm and a fill length of 55 mm. Preliminary experiments yielded the following results: at an operating frequency of 60 Hz, an input power of 20 W, a hot end temperature of 80 K, and an operating pressure of 1.5 MPa, the minimum no-load temperature achieved was 13 K, and a cooling capacity of 1 W at 28.2 K was obtained at 52 Hz.

Human space exploration is becoming more frequent with the rapid development of modern space technology. The pulse tube cryocooler is an indispensable part of the space probe, but the cost of launching space probes restricts their volume and weight. Therefore, it is particularly important to improve the performance of the pulse tube cryocooler under the premise of limited volume and weight. This paper develops on a single-stage, high frequency, lightweight coaxial pulse tube cryocooler. This cryocooler is driven by a linear compressor with a total mass of 2.5 kg, using the inertance tube and gas reservoir as phase shifters. The cold finger has a diameter of 14 mm and a length of 55 mm. At an operating frequency of 102 Hz, an input power of 100 W, a hot end temperature of 293 K and a charge pressure of 6 MPa, a minimum temperature of 31.7 K and a cooling capacity of 1.5 W at 47.7 K can be achieved. In this paper, the related parameters that affect the performance of the cryocooler are introduced in detail, which are mainly charge pressure, hot end temperature and cold finger direction.

To develop a long-wavelength infrared (LWIR) detector, a 40 K pulse tube cryocooler is needed to provide reliable and low-noise cooling power. Traditionally, it is generally believed that to improve efficiency, a 40 K pulse tube cryocooler needs to operate at around 40 Hz. However, low frequency cryocoolers are heavier and are not preferred for use on satellites. In this paper, a lightweight pulse tube cryocooler working at 76 Hz is designed. The inertance tubes, along with the reservoir, serve as the only phase-shifter to guarantee the stability. Currently, the cryocooler has a cooling capacity of 9 W at 40 K while operating at 500 W of electrical power, and it weighs only 7.8 kg. The efficiency relative to the Carnot efficiency was approximately 11.1%. The performance characteristics of the designed cryocooler are presented in detail.

The Einstein Probe (EP) satellite is designed for X-ray time-domain astronomy. The Follow-up X-ray Telescope (FXT) is one of the scientific payloads onboard EP. It will mainly be used for the follow-up X-ray observation, and it will also be used for the sky survey and Target of Opportunity (ToO) observation. The focal plane detector of FXT provided by the Max Planck Institute for Extraterrestrial Physics (MPE) adopts a PNCCD sensor. For detector cooling, a helium pulse tube refrigerator is used, provided by the Technical Institute of Physics and Chemistry (TIPC), Chinese Academy of Sciences (CAS), to keep the detector working at a temperature of −90 ± 0.5 °C. The PNCCD driving and data acquisition electronics are developed by the Institute of High Energy Physics (IHEP), CAS. To observe different celestial sources, we designed six filter wheel positions and three scientific operating modes for the PNCCD detector: the full-frame mode, the partial-window mode, and the timing mode. In the full-frame mode, the system frame rate is 20 frame/s and the energy resolution of the whole system reaches 92 eV @ 1.49 keV (FWHM). The frame rate of partial-window mode is 500 frame/s. In the timing mode, the time resolution is about 94 μs. This paper mainly introduces the design and test results of the focal plane camera.

An infrared detector represents a crucial instrument for human exploration of the universe. The pulse tube cryocooler is a widely utilized technology for the cooling of various types of infrared detectors. At present, the development of pulse tube cryocoolers, which can operate at lower temperatures and have higher cooling capacity, has become an important development direction in this field. In order to achieve this objective, a pulse tube cryocooler with a substantial cooling capacity in the lower temperature zone has been developed, in this study, a high-frequency pulse tube cryocooler operating at 70 K with a total weight of 4.7 kg, a cold finger diameter of 25.6 mm, and a length of 51 mm. The regenerator is filled with #600 and #500 stainless steel screens. Under the conditions of input power 200 W, hot end temperature 300 K, operating frequency 106 Hz, and charge pressure 6MPa, the minimum temperature is 32.4 K, and the cooling capacity of 10 W can be obtained at 70.75 K, the relative Carnot efficiency is 16.35%.

As the fundamental component of the pulse tube cryocooler, the functionality of the regenerator exerts a direct influence on the overall performance of the cryocooler. In the design of a pulse tube cryocooler, two principal structural options for the regenerator are available, contingent on the specific requirements. One option is a non-variable cross-section structure, while the other is a variable cross-section structure. The advantage of the variable cross-section structure is that it allows the pulse tube cryocooler to increase the cold end heat exchanger at the variable cross-section for cooling, thereby enabling the cryocooler to operate in different temperature zones. Furthermore, a multi-bypass configuration can be added at the variable cross-section region of the regenerator to enhance the phase modulation capacity of the inertance tube. Consequently, the mass of gas entering the cold end heat exchanger is reduced, which in turn diminishes the cooling capacity. The variable section structure presented in this paper is based on the design and processing experience of the single-stage pulse tube cryocooler. The design parameters are as follows: The diameter of the primary regenerator is 16 mm, with a filling length of 40 mm; the diameter of the secondary regenerator is 10 mm, with a length of 30 mm; and the packing of the regenerator is comprised of #500 and #635 stainless steel screens. The cryocooler was subjected to testing under varying operating pressures. At an input power of 100 W, an operating pressure of 4.2 MPa, a hot end temperature of 300 K, and an operating frequency of 92 Hz, a no-load temperature of 32.16 K and a cooling capacity of 1 W at 44.44 K can be achieved.

A micro coaxial pulse tube cryocooler has been developed for infrared detection. This paper presents the experimental data of performance and describes the optimization process of a pulse tube cryocooler in detail. With a tiny size and high frequency, this cryocooler is driven by the linear compressor. The combination of inertance tube and buffer is adopted as phase shifter. The effect of the structure and operating parameters on cooling performance are investigated through experiments. As a result, the regenerator has a dimension of 40 mm length, and the optimal frequency is 175 Hz. It can provide a cooling power of 0.5 W at 80 K with a 30 W input electric power and 0.8 W at 150 K with a 10 W input electric power.

A micro coaxial pulse tube cryocooler has been developed to meet the requirements of high operating temperature infrared detection in space applications. To increase the efficiency of the cryocooler, the optimization experiments were designed. Driven by a double-piston opposed linear compressor with the mass less than 200 g, this cryocooler uses the inertance tubes and a reservoir as phase shifter and has the regenerator with a diameter of 10 mm. The effect of the operating frequencies and charging pressure on cooling performance were investigated through a series of experiments. This cryocooler can provide a cooling power of 0.61 W at 150 K with an input electric power of 10 W. This paper describes the optimizing processes and presents test data in detail.