Abstract
This paper presents the operation status and results of ground thermal cycling test of pulse tube refrigerators (PTRs) for space application. Firstly, a thermal cycling degradation model was proposed by considering two physical mechanisms: contamination and fatigue damage. Then, a thermal cycling test scheme of two types of PTRs was designed and performed to demonstrate their long lifetime and high thermal stability. Two type A PTRs with cooling capacity of 1W@60 K and two type B PTRs with cooling capacity of 5W@80 K were continuously operated for about two years in a simulated vacuum thermal cycling environment. Effects of heat rejection temperature variation on thermal stability and dynamic performance of the PTRs were investigated. Furthermore, the thermal cycling degradation model was validated with the actual thermal cycling test data. Finally, the predicted pseudo-failure lifetime was acquired via experimental data and degradation model. Moreover, the estimated reliability of PTRs was obtained through using the Weibull distribution. The proposed thermal cycling test scheme and innovative lifetime prediction and reliability estimation method provide a quick and accurate approach for the cooler manufacturer to assess the lifetime and reliability of the space PTRs.
Highlights
Cryogenic technology has become more and more important as cryogenic detectors play a critical role in the fields of meteorological forecast, earth observation, and astronomical research. e long-life infrared detectors are required to operate at a cryogenic temperature in order to decrease background noise and provide high sensitivity and resolution [1,2,3]
Based on the above outgassing property of nonmetal materials and thermal cycle fatigue model, a theoretical thermal cycling degradation model is established to describe the correlation between power consumption increment of the pulse tube refrigerators (PTRs) and cycle number, reject temperature fluctuation, thermal cycling frequency, and maximum reject temperature based on the following assumptions: (1) ermal cycling is the only related factor for performance degradation of the PTRs
As the PTRs have to provide sufficient cooling for the science instruments and optical system as well as to meet the 8 years lifetime requirement, the failure criterion of pulse tube refrigerator is mainly determined by the power consumption increment and the cold-tip temperature
Summary
Cryogenic technology has become more and more important as cryogenic detectors play a critical role in the fields of meteorological forecast, earth observation, and astronomical research. e long-life infrared detectors are required to operate at a cryogenic temperature in order to decrease background noise and provide high sensitivity and resolution [1,2,3]. To satisfy the growing demand, PTRs should address the technical parameters and must reach the requirements in term of temperature stability, operating reliability, and lifetime that critically affect the sensitive detectors. It is a great challenge for the PTRs which must maintain long-term stable operation with predictable performance despite a rigorous operating environment. E space cryocoolers in the laboratory can achieve the required technical parameters such as cooling temperature and cooling power Whether they can operate stably for more than 8 years in a dynamic space environment needs to be systematically investigated and demonstrated.
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