被动型氢原子钟吸气剂泵的应用研究

描述了上海天文台在2008年为提高被动型氢原子钟真空系统的可靠性所研制的由非蒸散型吸气剂泵和小离子泵组成的复合泵的实验过程,吸气剂泵在室温下吸收2.1MPa.l的H2气后仍可达到3.2×10-5Pa的真空度,2l/s的离子泵电流工作在0.30μA,证明了复合泵可以维持氢钟13年以上的正常工作。经过再激活固定了激活工艺,吸气剂最终吸氢6.0 MPa.l仍没有饱和,证明了吸气剂的强大吸氢能力。至今复合泵已成功应用在4台被动型氢钟上。     

Recent innovations in barrier technologies for plastic packaging—a review

The barrier solutions presently available on the market all have their drawbacks, e.g. cost, water‐sensitivity, opacity or perceived environmental bad‐will. At the same time there is a trend to use more plastic‐based packaging materials for different applications, e.g. as replacements for metal and glass containers. This situation has stimulated the industry to provide new, more efficient barrier solutions. The innovations go along five major lines: (a) thin, transparent vacuum‐deposited coatings; (b) new barrier polymers as discrete layers; (c) blends of barrier polymers and standard polymers; (d) organic barrier coatings; and (e) nanocomposite materials. This paper provides a comprehensive review of the different approaches, outlining the principle behind each barrier technology, its performance, its potential and the companies developing and producing the materials. Copyright © 2003 John Wiley & Sons, Ltd.     

A new generation of getter‐coated sputter ion pumps for XHV applications

A new concept of sputtered ion getter pump is presented. The body of this pump is internally coated by a getter thin film constituted by a layer of TiZrV together with a protective covering of palladium, according to a technology that CERN (European Center for Nuclear Research) licensed us. TiZrV is a well‐known alloy able to pump getterable gases such as hydrogen, oxygen, nitrogen, carbon monoxide and dioxide. With the exception of H², the sorption of these gases is not reversible and it causes a progressive contamination of the bulk of the material. With the addition of the palladium overlayer, the pumping action is limited to hydrogen and carbon monoxide, but the lifetime of the film is strongly enhanced, thanks to the possibility of an unlimited number of thermal activations, which restore the initial performances of the film. An innovative sputter ion pump design, optimized for both pumping speed in ultra high vacuum and getter film sputtering, will be introduced. Moreover, pumping speed measurements and ultimate pressure data, obtained after a relatively short bake‐out at temperature lower than standard procedures, will be reported.     

Applications of non evaporable getter pump in vacuum metrology

Applications of non evaporable getter pump in vacuum metrology are reviewed and discussed with a special focus on static expansion primary vacuum standard, and flow division method ultra-high vacuum (UHV) and extremely high vacuum (XHV) standard. The results obtained show that the non evaporable getter pump is suited for extending the calibration lower limit, and it is a valuable supplement to the basic methods. The feasibility of use of non evaporable getter pump in constant conductance method vacuum leak standard is also discussed.     

小型锆吸气泵在真空靶室中的应用研究

本文主要介绍了锆吸气泵的原理,以及在真空靶室上应用锆吸气泵所获得的良好结果,为解决靶室静态真空保持问题提供新的思路和技术方法。     

New high capacity getter for vacuum insulated mobile LH2 storage tank systems

Current “Non-evaporable getters” (NEGs) are important for the improvement of vacuum by the help of metallic surface sorption of residual gas molecules. High porosity alloys or powder mixtures of Zr, Ti, Al, V, Fe and other metals are the base material for this kind of gas sorbents. The development of vacuum technologies creates new challenges for the field of getter materials. The main sorption parameters of the current NEGs, namely, pumping speed and sorption capacity, have reached certain level limits. Chemically active metals are the basis of NEGs of a new generation. The appearance of new materials with high sorption capacity at room temperature is a long-felt need. It is obvious, that chemically active metals and alloys with reactivity higher, than that of transition metals, can become this kind of materials. The potential of active metals as the strongest gas sorbents is very high. The improved getter materials allow faster pumping speed. The sticking rate on the chemically active surface is significantly higher, and sorption capacity can be increased by up to 104 times (during the life-time of a device the entire getter material reacts with residual gases). The main structural form of the new getter concepts are spherical powders, granules and porous multi-layers. The full pumping performance takes already place at room temperature and the activation temperature can be adjusted between room temperature and 660 °C. The successful insertion of this new chemical getter pump in a mobile double-walled LH₂ tank system shows the very high sorption capacity of all relevant residual gases including H₂. This new invention opens the possibility for significant vacuum improvements especially in the field of H₂ pumping, which is an important challenge in many different vacuum devices and processes.     

Mikrowellen‐PECVD für kontinuierliche Großflächenbeschichtung bei Atmosphärendruck

Microwave PECVD for continuous wide area coating at atmospheric pressure Plasma processes are applied for a variety of surface modifications. Examples are coatings to achieve an improved corrosion and scratch protection, or surface cleaning. Normally, these processes are vacuum based and therefore suitable to only a limited extend for large area industrial applications. By use of atmospheric pressure plasma technology integration in continuously working manufacturing lines is advantageously combined with lower costs and higher throughput. Microwave plasma sources present powerful modules for plasma enhanced chemical vapour deposition at atmospheric pressure. At Fraunhofer IWS processes and equipment as well as application specific materials are developed. The coatings are suitable for scratch resistant surfaces, barrier and corrosion protective layers or anti‐reflex layers on solar cells. The film properties achieved are comparable with those produced by low pressure processes.     

Surface area, pore size distribution and microstructure of vacuum getter

An effective getter is necessary in vacuum technology. In order to obtain the adsorption mechanism of the getter, its microstructure information must be studied. Surface area, pore size distribution and microstructure of vacuum getter were studied with XRD, SEM and N₂ adsorption technique.Vacuum getter is composed of the different proportions of PdO and Ag₂O. The crystalline size of 3^# vacuum getter that includes W₂AgO = 22% and W_PdO = 78% is the maximum among all the vacuum getters. SEM images showed that vacuum getters expose a large number of nanometer-size pores. The adsorption isotherms of the vacuum getters are typical of type Ⅳ, characteristic of mesoporous material, and a type H₂ hysteresis loop is observed. Langmuir model describes N₂ adsorption at low pressure region. At the medium pressure, N₂ adsorption can be modeled by BET model. The pore size distributions of the vacuum getters are calculated by applying BJH method to the adsorption branch of N₂ isotherms at 77 K. With percentage of Ag₂O elevation, Langmuir surface area, BET specific surface area, the adsorption capacity and the pore volume become larger. But the average pore diameter becomes smaller. However, above Ag₂O content of 22%, an inverse behavior is observed. 3^# vacuum getter has the highest surface area and pore volume among all the vacuum getters. The experimental results and related analysis can be adopted in the later design of the vacuum tank.     

Getter films with a reactive component

Abstract

Numerical solutions for the sorption problem for the films of the solid solutions of the reactive metal under a constant pressure P of the sorbed gas have been found. These solutions depend on the value of the kinetic coefficient H, which is proportional to gas pressure P. According to the found dependence the relative sorption capacity S of the getter film is the larger the smaller is pressure P, and this relation between the values S and P is due to the concentration changes taking place in the getter material during the diffusion of the reactive component to the film surface. The practical importance of the dependence of S on P is obvious: it serves the basis for a new method of increasing the efficiency of the getter materials and increasing the life span of vacuum devices by controlling the value P.     

Organische UV‐Schutzschichten für die Polycarbonatverglasung

Organic UV‐protective coatings for polycarbonate glazing Polycarbonate as glazing material in outdoor applications requires functional UV protective and scratch resistant coatings. The vacuum coating technology offers a wide range of deposition processes to produce such complex coatings. The Fraunhofer IOF developed an effective UV protection by the deposition of organic UV absorbers. Thermal evaporated organic compounds were investigated as single layers and hybrid layers in a SiO₂ matrix. The UV‐stability of such coatings was increased significantly.     

电真空器件残气质谱分析和贮存寿命的快速测试研究

电真空器件内的残气压强是制管和管子工作过程中管内吸气剂材料吸气后形成的平衡压强,器件击破后质谱分析室本底气体会被吸气剂吸收。因质谱分析室放出的本底气体量一般远小于吸气剂在器件内原吸收的气体量,故器件内的残气压强的新平衡值增量可以忽略,分析室本底不会影响正确的分析结果;大气漏入管内后只表现出该管内惰性气体氩的积累;据此,我们提出了充氩法贮存寿命的快速测试方法。只有吸气剂失效或吸气饱和后管内残气质谱图才反映出漏入的大气成份或分析室本底气体干扰的特征。     

主动型氢脉泽物理系统的小型化

为实现主动型氢原子钟脉泽的小型化,对其物理结构进行了优化设计。其中,腔-泡结构、真空系统、C场线圈、束光学系统、磁屏蔽系统均被理论分析和优化设计,并进行了相关的验证实验。双真空结构设计有效地减小了氢脉泽的尺寸。在此基础上,对空间应用主动型氢原子钟的地面样机进行了研制,复合泵技术进一步减小了主动型氢原子钟的尺寸和重量。     

Herstellung funktionaler organischer Dünnschichten durch Vakuumverdampfung

Depositing of functional organic thin films by vacuum evaporation Material evaporation under high or ultra‐high vacuum conditions has been a well known method of thin film coating since nearly a hundred years. Since discovery of semiconducting organics in the 1970s and 1980s, this technology has been increasingly applied to deposit organic molecular compounds. At the moment especially materials for organic LEDs (OLEDs) and for thin‐film solar cells are in the focus of interest. While organics evaporation makes use of advantages of high‐vacuum coating (purity, compatible processing, masking etc.) there are also dedicated demands on process control coming up. The article describes basic requirements, capabilities of present temperature‐controlled evaporation sources, material‐related features, as well as typical applications.     

Static expansion vacuum standard with extended low pressure range

The main factor to affect lower limit of static expansion vacuum standard is outgassing of the inner surface. A new method has been demonstrated to extend the lower limit by using a non-evaporable getter pump (NEGP) to eliminate the outgassing influence. Because NEGP has no pumping speed for inert gases, it can maintain the ultra-high vacuum background without changing gas quantity in the calibration chamber when an inert gas is used as the test gas, which makes the standard pressure accurately calculable by Boyle’s law. By this method, the lower limit of static expansion vacuum standard has been extended to 10⁻⁷ Pa.     

真空绝热容器夹层吸附剂盒的结构设计

绝热夹层的真空度，是保证真空绝热低温容器之绝热性能的关键因素。而合理设计夹层中的吸附剂盒，又是维持夹层真空的重要环节。讨论了吸附剂盒的结构设计要点。     

Der Alleskönner der Messtechnik

The all‐rounder of measurement technology – Monitoring of vacuum properties The Novion is an all‐rounder of vacuum measurement technology. The newly developed sensor is based on a novel ion source and an integrated TOF mass spectrometer. The new vacuum measuring instrument is versatile: precise total pressure measurement over a wide range and simultaneously determination of helium partial pressure and residual gas analysis. By using the patented ion source, the instrument also achieves a high dynamic range without the use of a cost‐intensive electron multiplier, down to the UHV range. The Novion comes with a compact design, easy maintenance and an intuitive operation. The article covers the fields of application of this multi‐method sensor and explains its functionality in detail.     

High‐Speed 3D Printing of Millimeter‐Size Customized Aspheric Imaging Lenses with Sub 7 nm Surface Roughness

Advancements in three‐dimensional (3D) printing technology have the potential to transform the manufacture of customized optical elements, which today relies heavily on time‐consuming and costly polishing and grinding processes. However the inherent speed‐accuracy trade‐off seriously constrains the practical applications of 3D‐printing technology in the optical realm. In addressing this issue, here, a new method featuring a significantly faster fabrication speed, at 24.54 mm³ h^?1, without compromising the fabrication accuracy required to 3D‐print customized optical components is reported. A high‐speed 3D‐printing process with subvoxel‐scale precision (sub 5 µm) and deep subwavelength (sub 7 nm) surface roughness by employing the projection micro‐stereolithography process and the synergistic effects from grayscale photopolymerization and the meniscus equilibrium post‐curing methods is demonstrated. Fabricating a customized aspheric lens 5 mm in height and 3 mm in diameter is accomplished in four hours. The 3D‐printed singlet aspheric lens demonstrates a maximal imaging resolution of 373.2 lp mm^?1 with low field distortion less than 0.13% across a 2 mm field of view. This lens is attached onto a cell phone camera and the colorful fine details of a sunset moth's wing and the spot on a weevil's elytra are captured. This work demonstrates the potential of this method to rapidly prototype optical components or systems based on 3D printing.     

Anorganisch‐organische Hybridschichten für die Entspiegelung optischer Oberflächen

Inorganic‐organic hybrid coatings for antireflection of optical surfaces The application of nanostructures for optical surfaces has been discussed since antireflective nanostructures have been discovered on the eyes of night‐flying insects. On injection molded plastic lenses, antireflective nanostructures can easily be produced by plasma etching. The procedure has now been adapted to vacuum evaporated organic layers. Complex coatings composed of inorganic layers and organic nanostructures are especially suitable for realizing broadband antireflection properties on glass lenses.     

Thin film getter coatings for the GSI heavy-ion synchrotron upgrade

For the future project the Facility for Antiproton and Ion Research (FAIR) at GSI, an accelerator system with a base pressure of 10⁻¹⁰ Pa is required. The low pressure is needed to reduce the charge exchange rate between the accelerated ions and the residual gas molecules and therefore to increase the ion beam lifetime. Among the different measures undertaken to upgrade the existing UHV system, the installation of non-evaporable getter (NEG)-coated dipole and quadrupole chambers is foreseen. For this purpose a licence agreement for the non-evaporable thin film getters was signed between GSI and CERN in the end of June 2005.A new dedicated magnetron sputtering facility was designed and commissioned at GSI to perform the Ti-Zr-V coating on the dipole chambers of the heavy-ion synchrotron (SIS 18).Those pipes, made from stainless steel, have an elliptical cross section, are 3 m long, and are characterised by a wall thickness of 0.3 mm and a 15° bending angle.The characterisation of the thin films produced has been carried out by Rutherford backscattering spectroscopy (RBS), energy dispersive X-ray spectroscopy (EDX) and elastic recoil detection analysis (ERDA) for the chemical composition, scanning electron microscopy (SEM) for the morphology, and X-ray photoelectron spectroscopy (XPS) for the activation behaviour.The coating facility, its operating mode, and the first results obtained on the NEG characterisation by means of the different techniques will be described.     

Die Molekularstrahleptaxie — vom Forschungsinstrument zum Industriellen Produktionswerkzeug

High technology molecular beam epitaxy (MBE) is a complex chemo‐physical crystal growth process for deposition of ultra thin monocrystalline layers on monocrystalline wafers. The goal is to obtain the crystal growth with precision of an atom in both, vertical as well as in horizontal direction. One most important condition is to achieve ultra high vacuum environment, it means, that in the deposition chamber is a background pressure in the range of 10^‐10 Torr or even better. Then the mean free path of the evaporated species is in the range of several hundred kilometers and there are no interactions between the molecules in the beams. The molecular beams come typically from thermally evaporated sources (effusion cells), but also different techniques are often used (chemical beam epitaxy — CBE, metal‐organic molecular beam epitaxy — MOMBE, gas‐source molecular beam epitaxy — GSMBE). Normally the molecular beams can be abrupted by individual source shutters with open‐close cycles of a few hundred milliseconds. Together with the natural very low growth rate of a few Ångstroms per second it is possible to composite atomically layers from one material to another.