The problem of current leads in superconducting devices

A method is described for determining the heat flux along electrical leads to a cryostat with liquid helium. Formulas are obtained which enable the heat flux to the liquid helium to be calculated.     

Measurement of the transient heat transfer to liquid helium from a thin metal film

A method to measure transient heat transfer to liquid helium from a thin metal film heater under the condition of pulsed heating during τ ≤ 400 ns is proposed. The experimental equipment used for the measurements is described. The method is based on the comparison of heat pulses transfered from the heater into a monocrystal substrate which is surrounded either by vacuum or by liquid helium. The method can also be used to investigate the heat flux density transmitted into liquid helium over a wide region of thermal loads. Experimental results showing the heat flux density radiated from a Cu heater into liquid helium at 3.8 K as a function of the electric power fed into the heater by pulses of 200–400 ns duration are demonstrated.     

A proposed new and quick method for measuring surface tension of liquid helium

Experimental difficulties in measuring the surface tension of liquid helium by the existing methods are discussed. A new, fast and reliable experimental technique for measuring the surface tension of liquid helium is described. The instrument is simple, compact and sensitive for such investigations. The principle of this method is to balance the downward pull due to surface tension on the edges of a glass-slide against the upthrust of liquid helium. The instrumental technique is flexible for modification, to facilitate the measurements of surface tension of other liquified gases and chemicals subjected to various physical conditions     

氦质谱正压检漏法

为了直接获得工作状况下的漏率 ,在模拟工况条件下 ,采用氦质谱检漏仪正压检漏法可满足这样的要求。这种方法具有广泛地推广价值。介绍了此方法的意义、检漏过程及计算公式。     

Method for extracting neon and helium from air

A new method for extracting neon and helium from air is described along with a laboratory installation of industrial scale output constructed to realize the new method. The results of the experiments on the installation which show the feasibility and the advantages of the new method are shown. The possibility of further improvements to the method is discussed.     

建立纯氙气中六氟乙烷含量的分析方法

介绍用FTV2 70 0型氦离子化气相色谱仪分析氙气中六氟乙烷含量的方法。     

The stabilization of temperature in miniature continuously filled He cryostats

This paper describes a continuously filled cryostat which consumes a negligible amount of liquid helium. The cryostat can measure temperatures below 4.2K to room temperature. The method of controlling the pressure of the exchange gas in the vacuum can will be described.     

AMS-02超导磁体中超流氦加注过程研究

论述了AMS-02超导磁体中超流氦的加注过程,进行了各个环节压降和温降的计算分析,并用图表表示了在不同质量流量加注超流氦工况下管路系统中氦工质的速度、压力、温度和含气量的变化情况.计算结果表明,氦工质从液氦主杜瓦加注到磁体杜瓦的过程中,其压力和温度不断降低,而含气量不断增加.同时也表明在节流阀VVP9中实现了常流氦向超流氦的转变和质量流量的控制.     

大型空间环境模拟设备的气氦制冷系统

介绍了大型空间环境模拟设备的气氦制冷系统,说明了气氦系统的作用、工作原理及组成,并与同类空间环境模拟设备的气氦制冷系统进行了比较与分析。     

The Use of Particle Image Velocimetry in the Study of Turbulence in Liquid Helium

Experiments are described in which Particle Image Velocimetry has been used to study turbulent flow in helium I. The possibility that this technique might be applied usefully to superfluid helium is explored briefly.     

A glass helium cryostat for optical and magneto-optical studies

A glass helium cryostat with copper shield for optical and magneto-optical studies is described. The shield-insert placed in the nitrogen dewar without hindering visual observation at the liquid helium level, prevents scattering of light by the bubbles of boiling nitrogen.     

A Low Power Photoemission Source for Electrons on Liquid Helium

Electrons on the surface of liquid helium are a widely studied system that may also provide a promising method to implement a quantum computer. One experimental challenge in these studies is to generate electrons on the helium surface in a reliable manner without heating the cryo-system. An electron source relying on photoemission from a zinc film has been previously described using a high power continuous light source that heated the low temperature system. This work has been reproduced more compactly by using a low power pulsed lamp that avoids any heating. About 5×10³ electrons are collected on 1 cm² of helium surface for every pulse of light. A time-resolved experiment suggests that electrons are either emitted over or tunnel through the 1 eV barrier formed by the thin superfluid helium film on the zinc surface. No evidence of trapping or bubble formation is seen.     

Semiconductor liquid helium level sensor

An all purpose liquid helium level detector utilizing a silicon transistor is described. The small size, low power dissipation, fast response time and tolerance of high magnetic fields combine to make this sensor suitable for the majority of helium level detection applications.     

Interfacing small closed-cycle refrigerators to liquid helium cryostats

Several different means of connecting small closed cycle refrigerators to liquid helium cryostats for the purpose of reliquefying the boiloff or reducing the boiloff rate are described. Interface principles which enhance the reliability and serviceability are presented. Most of the interfaces which are described permit the refrigerator to be serviced while maintaining liquid helium in the cryostat.     

新型氦气体轴承透平膨胀机的研制

着重介绍所开发的新型氦气体轴承透平膨胀机的主要设计参数及关键部件的结构，该氦气体轴承透平膨胀机用于空间环境模拟的氦制冷系统，在设计中，利用多目标优化程序获得了较好的热力性能及较高的失稳转速，同时还开展了不同工质的相似模化研究，以便更好地预测氦透平膨胀机的热力性能，为了测试透平膨胀机的热力性能及机械性能，进行了多次的常温空气试车及液氮级温度低温试车，试验结果及现场实际车结果表明氦气体轴承透平膨胀机具有优异的热力性能及机械性能，满足了神舟号飞船发射前的热真空试验要求。     

Versatile experimental low power 4 K cryocooler

The construction of a low power cryocooler consisting of a five-stage plastic Stirling cooler with an additional Joule-Thomson stage is described. Among its novel features are a contamination-free, pneumatic helium compressor and displacer drive. Valve timing is under computer control. Titanium foil embedded in the cylinder wall reduces helium diffusion through the plastic. The Joule-Thomson stage uses the same low pressure helium as the Stirling stages. The Stirling system cools down below 9 K. The Joule-Thomson stage delivers a few mW cooling at 4.2 K.     

A cryostat enabling thermal conductivity measurements of specimens deformed plastically at liquid helium temperatures

A new type of cryostat is described which enables tensile plastic deformation of copper alloys at liquid helium temperatures and measurements of thermal conductivity to be made without allowing the samples to age at temperatures above the liquid helium range. The cryostat has also been adapted for residual electricity resistivity measurements.     

空分设备产品气体纯度和允许漏率的计算

为了保证空分设备产品的纯度,必须考虑各个设备有可能对产品污染的具体情况,提出对各个设备允许漏率的具体要求及对精馏塔的分离纯度要求。详细介绍了漏率及最大允许漏率的计算以及转换到图纸标注设备允许氦质谱检漏的漏率计算方法,最后以空分设备的主冷为例,对氦质谱检漏要求的漏率最大值进行了演算。     

An efficient continuous flow helium cooling unit for mossbauer experiments

A Mossbauer continuous flow cooling unit for use with liquid helium over the temperature range 4.2–300 K is described. The cooling unit can be used for either absorber or source studies in the horizontal plane and it is positioned directly on top of a helium storage vessel. The helium transfer line forms an integral part of the cooling unit and feeds directly into the storage vessel so that helium losses are kept to the minimum. The helium consumption is 0.12 / h^-1 itat 4.2 K decreasing to 0.055 / h-1 at 40 K. The unit is top loading and the exchange gas cooled samples can be changed easily and quickly.     

Liquid helium transfer with a two-phase jet pump

A new two-phase helium jet pump is described. It may be possible to transfer helium or other cryogenic liquids with a two-phase jet pump that has no moving parts. The pump delivers subcooled liquid for filling the receiver tank without venting. The amount of vapour discharged is about the same as for transfer by receiver-tank venting.