High Vacuum Applications Research Articles

A paper in our education series: The theory and practice of vacuum science and technology in schools and colleges

The equilibrium pressure attainable in a vacuum system is limited by gas influx from vaporization, desorption, diffusion and permeation. This imposes stringent requirements on the physical properties of the material used for the fabrication of the system, and leads to the selection of a limited number of suitable materials, especially if ultrahigh vacuum pressures are to be achieved. The properties and performance of such materials, namely glass, metals, ceramics and, in some application, synthetics, are reviewed in this article. Data on the physical parameters and preparation procedures, pertinent to their use in ultra high vacuum application, are given.

Abstract: Controlled-energy micropositioning system for high-vacuum applications

The operation of a high-performance positioning system within a high-vacuum environment poses several restraints on configuration and materials selection. To overcome these physical design limitations and reduce their effect on the dynamic performance of the positioning system, a technique for achieving optimum energy usage during stepping has been developed and evaluated. Principles used in developing this technique are reviewed; their application is illustrated through the use of simulation techniques and actual test results. System design requirements, control system configuration, and simulation will be discussed. Dynamic performance and accuracy objectives are emphasized.

An integrated, high vacuum, beam modulation device

A piezoelectric element employed as a vibrating-reed beam modulator inherently possesses characteristics which allow the device to operate as a self-maintaining oscillator. The electrical drive, resonant frequency and controlling feedback are all integral properties of the multimorph. The resulting chopper is remarkably simple to make, highly stable and ideally suited for high vacuum applications.

An Electron Bombardment Substrate Heater for Use with Very Thin, High Resistivity Substrates

An electron bombardment substrate heater has been designed for reproducible uniform heating to ∼900°C of very thin high resistivity disk shaped silicon wafers. The contact area of the wafer with heater hardware is kept minimal and the heater is suitable for high vacuum application.

Glass-bonding techniques for semiconductor strain gages

Conventional organic-epoxy adhesives outgas when exposed to ultra-high vacuum and, as operating temperatures are increased, they begin to exhibit plastic behavior causing hysteresis and zero instability in the transducer. The use of an inorganic glass as the bonding material has resulted in a significant advance in transducer-fabrication technology for the following reasons: 1. The outgassing of transducers in high-vacuum applications is minimized. 2. Mechanical properties of the transducer such as hysteresis and repeatability are improved. 3. The electrical isolation of the strain gages from the metallic elements of the transducer is increased at high temperatures over that provided by epoxy. Also, the glass bond can survive and operate in severe radiation environments, wherein the epoxy adhesive will suffer either temporary or permanent loss of its dielectric strength. 4. Glass-bonding techniques are particularly useful for the extension of the temperature range of operation of silicon-strain-gage transducers.

Articulated vacuum line

An articulated vacuum line is described which provides a flexible connecting means for relatively high vacuum applications.

1733. Lubrication and wear fundamentals for high vacuum applications: R L Johnson and D H Buckley,Rep NASA-TM-X-52271, 1967 ( NASA Lewis Res Centre, Cleveland, Ohio)

Lubrication and wear in high vacuum, considering inability to maintain oxide films, evaporation of lubricants, heat transfer and sliding friction

Paper 31: Lubrication and Wear Fundamentals for High-Vacuum Applications

The problems of lubrication and wear in vacuum are mostly caused by the low pressure and the lack of oxygen. Important considerations are: (1) inability to maintain oxide films; (2) evaporation of lubricants and (3) poor heat transfer. The usefulness of the adhesion concept of friction is demonstrated by correlation of cleavage and adhesion studies with sliding friction. Behaviour of solids in these areas of study is significantly influenced by crystal structure and atomic bonding forces. Better definition of surface, lubricating films and slider material on the basis of atomic arrangement in crystals and molecules is required for continued progress. Metals and alloys with hexagonal crystal structure and a c/a stacking ratio approaching ideal (1·633) have useful friction and wear properties. Crystal structures of inorganic lubricants are also important. Adhesion between surfaces in sliding contact may result in junctions formed from (1) diffusion bonding (i.e. solid solubility), (2) chemical bonding and (3) mechanical bonding. Material transfer occurs during sliding with most material combinations by one or more of these adhesion processes. Properties such as the proper hexagonal structure or contamination films that cause subsequent shearing to occur in the plane and region of the original interface will minimize adhesive wear. Friction responds to factors such as crystal structure that influence the shear strength of metal junctions. Methods for maintaining useful surface contamination and obtaining proper crystalline structure are the most promising areas for study in achieving efficient operation of sliding surfaces in vacuum. The problems as well as materials for their solutions need to be defined on the basis of atomic structure.

Tools for the Industry

A Selection of Equipment of Use in the Production and Maintenance of Aircraft, Missiles, Space Vehicles and their Components. A versatile, easily demounted stainless steel chamber 14 in. dia. × 20 in. high has recently been produced by Edwards High Vacuum Limited for general purpose ultra high vacuum applications.

Practical Vacuum Techniques

W. F. Brunner, JR., and T. H. Batzer New York: Reinhold; London: Chapman & Hall. 1965.Pp. x + 198. Price £3. 6s. There has been a spate of books on high vacuum subjects in recent years, but the needs of laboratory and industrial technicians have been largely neglected. The authors of the work under review recognize that success in the new fields of high vacuum application, such as titanium production and plasma research, depends greatly upon the correct use of vacuum technology.

The properties of Viton “A” elastomers: I. Determination of the sorption and air solubility characteristics of Viton “A” and their effect in vacuum applications of the material

The solubility of atmospheric constituents in Viton “A” has been evaluated from long-term sorption data. The solubility of air in Viton “A” elastomer at 18°C and at a relative humidity of 50 per cent was found to be 4.25 atm. cc per cc of elastomer with a deviation of ±3.5 per cent. From previously published data it is deduced that the sorbed gases are mainly water vapour and carbon dioxide. The overall sorption mechanism is discussed in terms of surface adsorption and diffusion into the bulk of the material. The time taken to reach any particular gas content depends on the diffusion coefficient, the temperature and the initial conditions (previous history) of the material. The influence of these factors on the gas emission process in high vacuum applications is discussed, using the model established for the sorption process. This suggests a reason for the apparent discrepancies in reported outgassing values. The advantages of pre-outgassing and storing under vacuum an elastomer intended for high vacuum use are demonstrated. A formula is quoted which appears to relate, for the samples tested, the cord diameter to the time required for decline in sorption rates.

A demountable electron tube for high vacuum applications

A demountable electron tube for high vacuum applications

A demountable electron tube for high-vacuum applications : A. Matthewson, Vacuum, 13 (10), Oct. 1963, 425

The advantages of cryopumping, e.g. high pumping speed, flexibility, cleanliness and wide pressure range of operation, have long been recognised. Nevertheless, industrial application of this method has been rejected so far. This paper describes the vacuum performance of a cryopump equipped with a recently introduced cryogenerator. The machine offers a cold production of approximately 50 W at 80 K and 10 W at 20 K simultaneously, thus eliminating the need for a liquid helium and (or) nitrogen supply. Data presented show that industrial applications of cryopumping at 20 K impose special requirements on the design of the cryopanels and the cold capacity of the cryogenerator. It is shown that a 10 W cold capacity will offer long term operation of the pump, particularly in industrial thin film coaters, if (a) hydrogen gas is distributed uniformly over an adsorbent glued on a 20 K panel, (b) the grain size of the adsorbent is about one millimetre, and (c) contamination of the adsorbent by gases more easily condensable than hydrogen is avoided.

A demountable electron tube for high-vacuum applications

A demountable electron tube for high-vacuum applications

Bearings for High Vacuum Applications

Bearings for High Vacuum Applications

High vacuum applications of polythene

High vacuum applications of polythene

High vacuum applications of polythene

High vacuum applications of polythene

High vacuum applications of polythene

High vacuum applications of polythene

High vacuum applications of polythene

The use of polythene in high vacuum work is discussed. The fabrication of polythene vessels, valves, taps, fine control valves, manometers, etc., is described, together with the use of polythene in jointing glass, metal, alumina and other ceramics to high vacuum lines.

Oil-Sealed Spherical Joints for High-Vacuum Application

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOil-Sealed Spherical Joints for High-Vacuum ApplicationClark E. Thorp and H.L. LandayCite this: Ind. Eng. Chem. Anal. Ed. 1945, 17, 11, 741–742Publication Date (Print):November 1, 1945Publication History Published online1 May 2002Published inissue 1 November 1945https://doi.org/10.1021/i560147a025RIGHTS & PERMISSIONSArticle Views25Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts