Temperature dependence of niobium superconducting nanowire single-photon detectors in He-3 cryocooler

Performances of superconducting nanowire single-photon detectors （SNSPDs） based on low Tc mate- rials strongly depend on the operating temperatures. We have fabricated infrared-sensitive niobium SNSPDs based on doped niobium （Nb＊） films and measured them in He-3 cryocooler. The critical current approaches to the de-pair- ing current at 0.3 K. Therefore, with the decrease in tem- peratures, we have observed a monotonous increase of count rate at the wavelength of 1,521 nm and exponential decrease of dark count rate at all bias currents. The possible origin of dark counts for doped Nb devices is also discussed.     

微型制冷机设计特点及联试结果分析

文章介绍了一种０．５Ｗ／８０Ｋ微型双活塞对置式斯特林循环制冷机的设计特点,并对设计思路及联试结果进行了分析。目前,该制冷机与红外探测器组件联试已取得成功,被冷却红外器件工作时温度低于７７Ｋ,室温成像效果清晰,已用于多元红外系统中。     

奇异G-M模型最小二乘估计新的相对效率

在奇异线性模型下利用2个矩阵特征根比值的最小值推广了Euclid范数定义的2种相对效率．文中研究了它们的下界,并给出了2种相对效率与广义相关系数之间的联系以及它们之间的关系,最后讨论了它们的性质,并研究了这2种相对效率的优越性．     

间壁式筛网网格换热器的性能分析

为揭示间壁式筛网网格换热器中网片与隔热片厚度比对换热器效率的影响规律,在数值计算中引入了间壁热阻和隔热片导热系数,改进了传统间壁式网格换热器的数值计算方法.通过与传统计算方法对比,发现改进方法使间壁式网格换热器计算更加精确并更体现其结构特点.利用改进的方法对换热器进行性能分析,得到了换热器效率及其内部温度分布特性.结果显示,隔热片与网片厚度的选取对换热器性能具有明显的影响,当隔热片厚度为0.2mm及网片与隔热片的厚度比为4∶1时,相同长度下的换热器性能达到最优.     

变质量二体问题及其解

该文采用Ｇｙｌｄｅｎ－Ｍｅｓｈｃｈｅｒｓｋｉｉ方程和Ｅｄｄｉｎｇｔｏｎ－Ｊｅａｎｓ定律研究了变质量二体问题并得到对于任意足值的Ｇ－Ｍ型变质量二体问题的解。结果表明由于主星的质量损失会使伴星的轨道半长径α产生一阶长期和周期项，轨道偏心率ｅ产生一阶周期和二阶混合项，近星点角角距ω产生一阶周期、二阶长期和混合项。文末，还对所得的结果进行了讨论。     

Performance of cryogenic regenerator with <Superscript>3</Superscript>He as working fluid

Almost all experimental and theoretical studies on regenerative cryocoolers at temperatures below 20 K mention the use of 4He as working fluid.A preliminary qualitative evaluation indicates that because of the superfluid phase transition,a working fluid of 3 He would overcome the cooling temperature limitation set by 4He.Starting with a comparison of the thermophysical properties of 3He and 4He,cryogenic regenerator simulations applied to the third/last stage of a pulse tube refrigerator,with 3He and 4He separately,were implemented to quantitatively analyze performance differences of the regenerator with respect to regenerator loss, cooling power and COP.Results conclude that 3He could significantly improve the performance of a regenerative cryocooler.