航天器上的氦制冷

综合介绍了氦制冷在航天器中的应用状况。氦制冷的温度低于4K。80年代以来,氦制冷在红外天文卫星、空间实验室、空间站、航天飞机所进行的许多与液氦温区有关的实验中得到了成功的应用。介绍了对低温的要求、应用状况、低温系统的特性。展望了90年代航天器中氦制冷的应用前景。     

航天器上的氦制冷

综合介绍了氦制冷在航天器中的应用状况。氦制冷的温度低于４Ｋ。８０年代以来，氦制冷在红外天文卫星、空间实验室、空间站、航天飞机所进行的许多与液氦温区有关的实验中得到了成功的应用。介绍了应用状况、低温系统的特性。展望了９０年代航天器中氦制冷的应用前景。     

氦制冷在90年代航天器上的新应用

80年代发射的红外天文卫星上的红外望远镜已开始采用超流氦制冷。这是为红外天文学设计的低温望远镜的具体应用。这种低温望远镜用于8～12μm 波段的空间观测。望远镜主镜的直径为40cm。蒸发制冷系统可以使其中的探测器的温度降到2.4K,光学系统的温度降到2.2K,寿命为1年。内部的氦容器呈圆柱形,周围装有光学系统。四周还有3个蒸发制冷屏和多层隔热系统.液相氦和气相氦的分离采用多孔塞式的相分离器来实现。多孔塞位于氦出口管与器壁的接口处。80年代在航天飞机上进行的红外天文学实验所用的氦制冷系统在小型化方面有所改进。     

空间低温光学试验深低温背景环境的实现

为了实现空间低温光学试验的深低温背景条件,对实现深低温环模技术以及氦冷却系统进行了探讨.通过分析得到以氦循环方式建立的20 K稳定深低温冷黑背景是最为合适的低温光学试验背景环境.该系统是由氦液化系统配合相应冷氦分配装置以及终端冷舱组成密闭循环系统.氦液化系统是基于由布雷顿循环和焦耳-汤姆逊作用组合而成的克劳德循环,它能持续提供一定流量和压力的液氦或冷氦气作为循环系统中制冷工质,从而为试验提供稳定的深低温环境.     

深冷文献消息(国内部分)

<正>983101 氦制冷在空间制冷技术中的应用徐烈等《低温工程》1998 №1 1~6介绍几种用于空间制冷中的氦制冷技术,如氦－3减压蒸发制冷、氦－3压缩相变制冷、亚临界液氦制冷、超流氦制冷等。分别介绍了它们的原理、关键技术及应用实例,最后提出了这方面工作的建议。     

大型氦制冷低温真空系统的设计研究

在大型空间环境试验设备的研制中,大型氦制冷低温真空系统的设计和制造有很大的技术难度,本文介绍了我国某大型窨环境试验设备中的大型氦制冷低温室系统的设计研究工作,对设计研究中的一些技术问题进行了研究探讨。     

液氢温区冷氦增压系统试验研究

针对某型号火箭冷氦增压系统,建设了液氢温区冷氦增压系统试验平台,通过试验得到了冷氦气源压力和温度、冷氦加热器性能、模拟贮箱压力和温度的变化规律.结果表明:低温制冷机组配合高压低温换热贮罐可以真实模拟箭上的冷氦气源;根据对增压过程中贮箱压力的分析表明排气方式可以真实模拟箭上推进剂消耗过程中贮箱压力的变化情况;另外,试验中压力信号器、电磁阀和贮箱工作正常,验证了火箭冷氦增压系统的可靠性.     

稳态强磁场实验装置低温系统360 W/4.5 K制冷循环热力学分析和优化计算

稳态强磁场实验装置的超导线圈采用4.5 K超临界氦进行冷却,制冷模式下,制冷机的设计容量为360 W/4.5 K.首先对氦制冷循环进行了热力学分析,然后以压缩机氦流量为优化对象,结合低温系统的工程要求,选取合适的参数,对制冷循环进行了优化计算.计算结果显示:液氮消耗量为28.50 L/h,压机消耗功率约102 kW,系统的制冷系数为0.003 5.     

氦透平膨胀机叶轮造型与设计方法

在制冷和低温系统中,氦低温系统的效率主要取决氦透平膨胀机的效率.利用ANSYA软件对氦透平膨胀机中工作轮和制动轮进行叶片造型,并对模型进行数值模拟计算.分析结果显示ANSYS可以比较方便快捷的设计出符合设计参数的透平膨胀机工作轮和制动轮,对提高氦透平膨胀机制冷效率和稳定性等方面都有实际意义.     

先进光源技术研发与测试平台(PAPS)2 K超流氦低温系统流程设计与计算

先进光源技术研发与测试平台(PAPS)2 K超流氦低温系统流程设计与计算需根据系统热负荷以及功能需求,进行方案设计和管道的规格选型,确定氦制冷机制冷能力.使用关联式编程计算方法对PAPS氦低温系统进行了流程模拟和计算,确定了2 K超流氦的获得方式,并研究了不同的节流前温度与节流效率以及相分离器供液质量流量的关系,重点介...     

超流氦低温系统发展及涡轮冷压缩机的应用

2 K下大型氦低温系统已采用离心式涡轮冷压缩机在低温低压下对饱和液氦槽减压操作,以获得超流氦或过冷氦.介绍了2K温度级超流氦制冷机发展情况和涡轮冷压缩机在氦制冷系统中的应用,以及中国科学院等离子体物理研究所EAST超导托卡马克氦低温制冷机中过冷氦的制取过程.     

低温节流阀的设计与计算

针对某超流氦系统所需要的低温节流阀,设计并加工了几种不同结构形式和尺寸的阀针.运用数值模拟方法分析了节流阀的流量特性,并运用实验的手段测量了其流量系数与阀门开度之间的关系.最终确定了一个适合该超流氦系统的较为理想的节流阀.     

ADS 2K低温系统超流氦换热特性研究

以ADS 2K低温系统为研究平台,分析了恒温器结构参数中上升管与峰值热量的关系,测量了超导腔液氦池中不同工作温度下的超流氦峰值热量,最后给出了恒温器上升管的设计方法,并验证了ADS低温恒温器上升管设计的合理性。     

In-orbit performance of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H

ASTRO-H was an X-ray astronomy satellite that the Japan Aerospace Exploration Agency (JAXA) developed to study the evolution of the universe and physical phenomena yet to be discovered. The primary scientific instrument of ASTRO-H was the Soft X-ray Spectrometer (SXS). Its detectors were to be cooled to 50 m K using a complex cryogenic system with a multistage adiabatic demagnetization refrigerator (ADR) developed by the National Aeronautics and Space Administration (NASA), and a cryogenic system developed by Sumitomo Heavy Industries, Ltd. (SHI). SHI’s cryogenic system was required to cool the ADR’s heatsink to 1.3 K or less in orbit for three years or longer. To meet these requirements, SHI developed a hybrid cryogenic system consisting of a liquid helium tank, a 4 K Joule-Thomson cooler, and two two-stage Stirling coolers.ASTRO-H was launched from Tanegashima Space Center on February 17, 2016. The initial operation of the SXS cryogenic system in orbit was completed successfully. The cooling performance was as expected and could have exceeded the lifetime requirement of three years.This paper describes results of ground tests, results of top-off filling of superfluid liquid helium just before launch, and cooling performance in orbit.     

Visualization techniques applied to thermo-fluid phenomena in cryogenic fluids

A variation of visualization techniques such as Shadowgraph, Schlieren and holographic interferometry, has been so far applied to visualize thermo-fluid phenomena in cryogenic fluids, superfluid helium (He II) and supercritical nitrogen, by some researchers. This paper is a review of these visualization techniques used in cryogenic fluids as well as an introduction of visualization techniques.     

The fast alternative cryogenic experiment testbed

Subsystems for a “proof of concept” cryogenic payload have been developed to demonstrate the ability to accommodate low temperature science investigations within the constraints of the Hitchhiker siderail (HH-S) carrier on the Space Shuttle. These subsystems include: a hybrid solid neon – superfluid helium cryostat, a multi-channel Versa Modular European (VME) architecture Germanium Resistance Thermometer (GRT) readout and heater control servo system, and a multiple thermal isolation stage “probe” for thermal control of helium samples. The analysis and tests of these subsystems have proven the feasibility of a cryogenic HH-S carrier payload.     

空间低温技术的进展

综合介绍国外，主要是美国、西欧空间低温技术的最新进展。论述超流氦冷却技术及空间飞行中的液氦再供给等在轨机载验证、低温风洞技术、氢浆的制备和应用前景等。重点讨论目前在空间探测过程中最具竞争性的斯特林制冷机和脉管制冷机的最新发展。对可望在空间中应用的毫开（ｍＫ）级３Ｈｅ—４Ｈｅ稀释制冷机和绝热退磁制冷机及其它制冷技术也作简要介绍。最后对发展我国空间低温技术提出了建议。     

Test of a model coil of "Tore Supra"

Inside the qualifying test programme, supporting the "Tore Supra" Tokamak design, a reduced scale model of coil was fabricated by an industrial firm and fully tested. This model coil is provided with the same features as those retained for the complete magnet and is built according to the same design; in particular the Nb-Ti mixed matrix monolithic conductor is cooled by a pressurized superfluid helium bath, supplied from a model of the envisaged complete cryogenic system. Three main objectives have been assigned to this test: operation of the cryogenic system, stability of the superconductor winding under high mechanical stresses, mainly shear, and simulation of coil quench conditions. For this purpose, the model coil (outside bore 0.8 m) is located inside a 4 T magnet, an hydraulic jack applies a 1 MN force along a coil diameter. Operation of the model coil has been found highly stable, under the conditions of applied field and forces, a coil transition can be induced by an electrical heater only when the superfluid bath temperature is close to Tλ. The 1.8 K cryogenic system provides a useful calorimetric measure of total losses induced inside the winding; its operation has been quite simple and reliable, permitting a sure extrapolation to a much larger size.     

Helium Adsorption on Lithium Substrates

We have developed a cryogenic pulsed laser deposition (PLD) system to deposit lithium films onto a quartz crystal microbalance (QCM) at 4 K. Adsorption isotherms of ⁴He on lithium were measured in the temperature range between 1.42 K and 2.5 K. The isotherms are qualitatively different from isotherms on strong substrates such as gold and weak substrates such as cesium. There is no evidence of the formation of solid-like layers of helium, and the helium coverage is approximately linear in the pressure over a wide range. By measuring the low coverage slope of the isotherms, the binding energy of helium to lithium was found to be approximately −13.6 K. For lithium substrates less than approximately 100 layers thick, the chemical potential at which the superfluid transition was observed was surprisingly sensitive to the details of lithium deposition. This work was supported by NSF grant DMR 0509685.     

Possible criteria for the ac Josephson effect in superfluid helium

Based on the differences between superfluid helium and superconductors in the dissipation mechanism of a weakly coupled system, an attempt is made to explain the possibility of observing an ac Josephson effect in superfluid helium with an orifice much larger than the coherence length of the superfluid helium. The temperature criterion for the ac Josephson effect proposed by Biswas is also discussed. The temperature needed for observing an ac Josephson effect in superfluid helium may not have to be much below 1 K.