镀膜设备真空系统主泵的配置

真空系统是真空镀膜设备的主要组成部分,其主泵的选择对真空性能影响很大,真空镀膜设备的发展要求真空性能清洁无油,动态抽速大.传统的以油扩散泵为主泵的设备不能满足要求,本文叙述了油扩散泵、分子泵及低温泵的特点及北京北仪创新真空技术有限责任公司开发以分子泵及低温泵为真空系统主泵的镀膜设备情况.     

Comparison of two pumping speed measuring methods of oil diffusion pumps

This paper presents a comparative study of two pumping speed measurement methods recommended for oil diffusion pumps. The methods used are the test dome method and the conductance tube method with an auxiliary pumping system which is used at very low pressures when the throughput is below 10^?5 Nm s^?1 (～ 0.1 μl s^?1). It is found that, in order to obtain the comparative results in the overlapping pressure region on the speed measurement of oil diffusion pumps by these two methods, the conductance tube in the conductance tube method should be located at a height 1.2 D from the pump mouth when the position of the inlet gauge is at a distance D/2 from the pump flange, i.e. at the same position as recommended in the dome method to obtain the intrinsic speed of the pump.     

Membranpumpen mit hoher Kompression durch tangentiale Membraneinspannung

Diaphragm pumps dominate the field of rough vacuum (down to 1 mbar) in modern industry and science. Their construction is quite simple and therefore warrants great reliability. Diaphragm pumps are oil‐free, maintenance free, have a low noise level and a long lifetime. Up to now, problems occurred in generating lower vacuum pressure. With a completely new tangential diaphragm insertion as well as with improvements of the gas flow, and the form and position of the valves, the of a Puchheim pump company now solved this problem: The tangential diaphragm pumps reach an ultimate pressure of 20 mbar (single‐stage) and less than 1 mbar (double‐stage). A pump head provides a pumping speed of 36 l/min at atmospheric pressure.     

罗茨真空机组预抽阶段的抽气特性比较研究

针对罗茨泵真空机组在启动预抽阶段的三种工作模式——旁通式、直通式和变频式,分别建立了简化计算模型,推导得出罗茨泵进入正常稳态工作之前罗茨机组的有效抽速计算公式,以及被抽容器的抽气时间计算方法.通过一个计算示例,对比得出了三种不同启动预抽方式的压力-时间曲线,结果表明,直通式、旁通式、变频式工作模式下容器的抽气时间依次减...     

Das Saugvermögen von Pumpen: Untersuchung verschiedener Meßverfahren im Grobvakuumbereich

The term pumping speed of a vacuum pump denotes the volume flow rate of gas removed by the pump. In a measurement of the pumping speed it has to be taken into account that the volume of a quantity of gas depends on pressure and temperature. The present article presents a critical investigation of two different procedures for measuring the pumping speed in the rough vacuum regime: In the first procedure, gas flows continuously through the test dome and the pump under investigation. The pumping speed is obtained from the stationary values of throughput and pressure in the test dome. This procedure is well established, technical details are described in various standards. In the second procedure, a large vessel with known volume is evacuated by the pump, and the pumping speed is derived from the pressure decrease with time. In order to avoid disturbances by thermal effects, the vessel may be pumped only during short time intervals with intermediate waiting for thermal equilibrium. The second procedure offers instrumental advantages and its practices are described in a new DIN standard. The physical basis and technical aspects of both procedures including disturbing thermal and other effects are investigated. If applied correctly at inlet pressures in the rough vacuum range, both procedures are expected to yield the same values of the pumping speed. Comparative measurements at a diaphragm pump confirm this expected behaviour within the experimental uncertainty of about 3% (2σ).     

油扩散泵抽气速率与被抽气体的关系

通过对油扩散泵抽气速率、气体分子平均热运动速度和分子流态下气体流导的分析，指出油扩散泵对不同气体的抽气速率具有选择性，给出了泵对不同气体和空气抽气速率比值的计算值，同时指出电离规的规管常数与气体种类有关。     

Experimental Study of Oil‐Free Claw Vacuum Pump Characteristics

Experimental study of pumping characteristics of a pilot model of a claw single‐stage vacuum pump with identical rotors was carried out. The curves of pumping speed vs. pressure at different rotary speed and the ultimate pressure at different rotors speed were determined on a test unit. Indicator pressure diagrams in working chambers of claw vacuum pump were obtained with the help of special sensors. Thus, an experimental data bank concerning the pumping characteristics of claw vacuum pump was created. It may be used for estimation of mathematical model adequacy and further development of the pump design.     

油封机械真空泵噪声机理再探

提出了一个新的观点，在油封机械真空泵中除了油锤现象产生的噪声外，同时存在着程度不同的汽蚀现象所引起的噪声，严重时还会造成汽蚀破坏，它取决于极限压力的高低，泵的大小和转速的高低，此外在滑阀真空泵中还存在着机械撞击噪声，提出了降低上述噪声的相应措施。     

Scroll Geometry of Scroll Vacuum Pump

The influence of the end part of the scroll on the pumping characteristics and indicated power of the oil free scroll vacuum pump is considered. With the help of developed mathematical model of the scroll pump dependence of pumping speed on the inlet pressure at different curvature radii of the scroll end part and compression duration is obtained. The influence of compression duration on the ultimate pressure and delivery rate is examined. Dependence of the indicated power on the inlet pressure at different number of scroll wraps and compression duration is calculated.     

喷嘴角度对水银扩散泵抽气性能影响的DSMC模拟研究

扩散泵由于其大抽速、连续稳态工作的优点,有望应用于未来聚变堆的偏滤器抽气系统中,以降低目前托卡马克装置中广泛采用的捕集式低温泵所带来的高氚存储量问题。由于氚相容性的限制,目前的商业油扩散泵无法直接应用于聚变堆中,水银将是理想的扩散泵工作介质。为了支持未来聚变堆偏滤器抽气系统的水银扩散泵设计,需要针对水银扩散泵开展设计优化研究。本文采用直接模拟蒙特卡洛方法,基于KT-150扩散泵结构,研究了喷嘴角度对水银扩散泵的抽气速度及水银返流率的影响。结果表明喷嘴角度为45°时能够达到最佳的抽气速度1.53m^3/s,同时返流率没有显著提升。     

Uncertainty analysis of the high vacuum part of the orifice-flow-type pressure standard

The orifice-flow-type pressure standard is commonly accepted as primary standard for vacuum gauge calibration in the high vacuum gas pressure range. It consists of two parts—a high vacuum part and a flowmeter. Practical questions arising at design of the standard have to be answered based on the standard uncertainty analysis.The analysis of the uncertainty sources in the high vacuum part except deviations from the Maxwellian distribution is given in the paper. Uncertainty of a precise flowmeter is taken from references for comparison. It follows from the analysis that uncertainties caused by some sources at routinely achievable parameters are negligibly small and further improvement brings no benefit. The crucial quantities influencing the total uncertainty are the temperature of the chamber and the flowmeter, the outgassing rate from the inner surfaces, the ultimate pressure of the pump and the additional (detrimental) pumping speed. The pumping speed of the main pump has to be “sufficiently higher” than the orifice conductance.     

分子泵对Xe气抽速的测试

在不同Xe气流量下测量了F-400／3500和F-250／1500分子泵对Xe气的抽速，指出分子泵对Xe气的抽速是其对N2抽速的0．6～0．8倍。这一折算系数和泵的型号有关，和泵口真空度也相关。     

Der Beginn einer Erfolgsgeschichte

The beginnings of a successful story The exciting invention of the molecular Pump by Wolfgang Gaede was followed by his new ‘Device of Producing High Vacua’ in 1913. It was announced in the second edition 1913 of E.Leybold's cataloge. Three years later Langmuir in the USA presented a similar pump called ‘condensationpump’, but with clearly better pumping speed. Another design of a pump with two stages was invented by Prof. Volmer in Berlin. Other European companies announced similar pumps. Because Gaede claimed the prinziple of evacuating gas by diffusion, he and Leybold succeeded in making all of them to ask for licences. Respective to Langmuir they exchanged licence to each other. By the time this ‘diffusion pump’ was produced from metal instead of glas, and used special mineral oil, not mercury. In the middle of the 20.century it became a most important tool for creating high vacuum, available with a few liters per second to some thousend liters of pumping speed.     

对油封机械泵一些主要性能的分析

该文介绍了油封机械泵的抽速与入口压力的关系、泵抽气效率下降的原因,指出泵入口管道的流导和油蒸汽逆流是造成泵抽速下降的主要原因.其次,还对油封机械泵的消耗功率与入口压力的关系进行了分析,指出最大功率时所对应的入口压力,同时还对泵油温度对功率的影响作了分析;给出对泵油性能的要求.     

Vacuum Challenges for Ion Thruster Testing

Electrical propulsion is the keyword for nowadays movement of space vehicles. Ionized particles, usually xenon ions, are accelerated by thrusters in an electric field. State-of-the-art xenon thrusters emit a gas flow of 0.1 to 10 mg/sec. In order to maintain a high vacuum pressure at this flow in thruster test chambers, a large pumping speed is required, often in the range of 10'000 to 100'000 l/s for xenon. The advantage of a large ion mass for the propulsion system is a major challenge for vacuum pumps. Leybold has developed an optimized and simple cryogenic solution for Xe pumping. Strong single-stage Gifford-McMahon type cold heads carry metal discs which condense the Xe gas with a pumping speed at the edge of the theoretical limit. In this work, we will present the whole vacuum system for a thruster testing facility.     

Fragen zu Vakuum‐Molekularpumpen

Questions about vacuum molecular pumps For experiments about gas friction we used a turbomolecular pump with magnetic bearings. The blade system was replaced by a cylinder of carbon fiber materal. lt rotates in a stationary aluminium cylinder at a distance of 0. 8 and 0. 4 millimeters at a rotating speed up to 48000 rpm. We got a linear dependance of the reciprocal values of pressure and viscosity in good agreement with other experiments in that field. Preparing experiments showed us our apparatus is working like a pump too. We saw differential pressures in dependance of flow and gas pressures. In our sytem pumping works against the flow resistance. The pumping range is limited by a graph showing the compensation of pumping and resistance. Here we have no flow through the system but only in tangential direction by the rotation The experiments showed graphs with 2 arms showing the compensaion of pumping and flow resistance. In the range between the arms the pressure difference reaches the highbest negativ numbers. That is the point of best pumping. The position of this point decreases to lower rotation frequencies with rising gas pressure and flow. The question is: what are the reasons for this behavior? Possibly the molecular pump developped by Siegbahn uses this effect. It makes higher compression rates by lowering the friction speed. The molecular pump of the Holweck type has at a constant rotation speed an optimal pumping effect at a certain nitrogen gas pressure and flow. At this optimum the pump makes high compression rates for additional hydrogen or helium.     

Überlastgrenzen bei Hochvakuumpumpen

High-vacuum pumps have a limited inlet pressure above which they cannot function. Recognizing and dealing with the approaching overload conditions is an important aspect of vacuum system operation. This paper outlines the basic considerations for selecting the pressure at which the high vacuum pumps are started, emphasizing the importance of mass flow (throughput) limits rather than the pressure as such. Some basic parameters, such as the ratio of pumping speeds of the roughing pump and the high vacuum pump are associated with the choice of the cross-over pressure. Practical engineering recommendations are offered for system design and operation. Adverse system effects (e.g., backstreaming and oil loss) resulting from pump overload are noted for momentum transfer pumps (diffusion pumps and turbomolecular pumps) and capture pumps (sputter-ion pumps and cryogenic pumps). To prevent any adverse effect, normally, the transient pressure rise during switching should not be longer than a few seconds.     

一种基于深冷混合工质节流制冷机的高真空水汽捕集器

详细介绍了一种新型的高真空深冷水汽捕集器.该深冷水汽捕集器采用单压缩机驱动的混合工质节流制冷机冷却,制冷系统采用商用单级油润滑压缩机驱动,在配套600 L涡轮分子泵时,压缩机的额定输入功率450 W,捕集器表面温度最低为110 K.在相同真空测试条件下,开启低温捕集器可使系统极限真空度和抽速均提高一个数量级.该新型深冷捕集器具有优异的性能、低廉的造价及高可靠性等特点,与其他高真空获得设备如涡轮分子泵结合可成为一种优异的洁净高真空获得系统.     

涡轮分子增压泵的研究现状与进展

综述了涡轮分子增压泵的研究现状与进展。涡轮分子增压泵是一种动量传输型真空泵，它的出口压力范围可达1000Pa，通过计算流体动力学方法(CFD法)和直接模拟蒙特卡罗法(DSMC)可以模拟计算抽气通道内气体的流动，这两种互补的方法可以研究从粘滞流到分子流的全部抽速曲线，从而指导新型涡轮分子增压泵的设计。     

The use of perfluoropolyether fluids in vapour stream pumps

The performance of a 5 in. diameter diffusion pump (Edwards EO4) has been studied using a distillation cut of the perfluoropolyether fluid with an average mass of 3000 amu. A pumping speed for air of 700 l/s was measured which is similar to the speed obtained when the pump is charged with Silicone 704 fluid. A higher critical backing pressure was obtained, however, for the new fluid viz 1.2 torr compared with 0.8 torr for the conventional fluid. Fragmentation spectra of the vapour molecule obtained by direct injection into the ion source and from backstreaming fluid showed prominent peaks at mass to charge ratios 31 and 69 corresponding to the fragments CF and CF₃. The similarity of the spectra obtained by the two methods suggests that the fragmentation takes place in the ion source and that the fluis is not degraded by use in the pump. An analysis of the pumping mechanism in vapour stream pumps is given.