(1) E. & F. N. SPON London VACUUM MANUAL. Edited by. W. Steckelmacher. J. Yarwood. L. Holland

Transcription

1 Vacuum Manual

2 VACUUM MANUAL Edited by L. Holland Formerly Director of Research Edwards High Vacuum; Associate Reader in Physics, Brunei University W. Steckelmacher Formerly Deputy Director of Research Edwards High Vacuum J. Yarwood Professor of Physics Central London Polytechnic (1) E. & F. N. SPON London

3 First published 1974 by E. & F. N. Span Ltd. 11 New Fetter Lane, London EC4P 4EE 1974 E. & F. N. Span Ltd. Soficover reprint of the hardcover 1st edition 1974 William Clowes & Sons Ltd. London, Colchester and Beccles ISBN DOl / ISBN (ebook) All rights reserved. No part of this book may be reprinted, or reproduced or utilized in any form or by any electronic, mechanical or other means, now known or hereafter invented, including photocopying and recording, or in any information storage and retrieval system, without permission in writing from the Publisher. Distributed in the U.S.A. by Halsted Press, a Division of John Wiley & Sons, Inc., New York Library of Congress Catalog Card Number

4 Contents Introduction page ix 1. Basic Data 1.1 Ultimate pressure (Pu) 1.2 Evolution of gas from materials Outgassing Degassing Vapour pressure 1.3 Permeation of gases through solids References 1.4 Gas flow in vacuum systems Maxwell's distribution of molecular velocities Mean free path, molecular diameter, viscosity Quantity of gas (as amount of substance) Flow regimes Viscous laminar flow in tubes Intensity distribution of gas issuing from tubes under molecular flow conditions Combined systems of tubes and components, conductance of composite systems Transient conditions Pump specifications and tests 44 References Conversion and other tables Pump fluids, sealing compounds and greases Impurities and degradation Pressure measurement problems Pump and trap effects Vapour pressure - measurement and use Pump fluids - chemical types Mineral oil distillates Chlorinated hydrocarbons Hydrocarbon waxes and greases Mineral oil lubricants Hostile conditions Mineral oil lubricants for rotary seals v

5 vi - CONTENTS Mineral oil lubricants in dry stage pumps and compressors Esters of - phthalic, sebacic and phosphoric acid Polyphenyl ethers Silicones and related compounds Perfluoropolyethers Backstreaming characteristics of vacuum pumps References 2. Vacuum Equipment 2.1 Vacuum pumps, valves and accessories Cryopumps Getter ion pumps Magnetless ion pumps Non-evaporable getter pumps Positive displacement pumps Roots pumps Sorption pumps Sputter-ion pumps Steam ejector pumps Titanium sublimation pumps Turbomolecular pumps Vapour pumps Water jet pumps Valves Vacuum accessories 2.2 Vacuum instrumentation Thermal conductivity gauges McLeod gauges and compression manometers U tube manometers Mechanical gauges Penning gauges Hot cathode ionization gauges Residual gas analysers Mass spectrometer leak detectors Leak detection instruments using search gas QIartz crystal surface density monitors Thickness monitors Rate meters Vacuum microbalances Optical film thickness monitors Ionization monitors Deposition process controllers page

6 CONTENTS - vii Vacuum switching or relay units Vacuum process controllers Surface analysis instruments 2.3 Vacuum process plant and vacuum systems General pumping units Chemical engineering applications of vacuum Vacuum metallurgy Vacuum furnaces Vacuum ovens Electron beam welding equipment Deposition plant: vacuum evaporation Vacuum evaporation special systems, vessel accessories and materials Sputtering plant. 2.4 Manufacturers' names and addresses page Recent Developments in Vacuum Science and Technology 3.1 Vacuum pumps; recent developments Introduction Positive displacement pumps Molecular drag pumps: the turbomolecular pump Getter pumps and getter-ion pumps Cryopumps References 3.2 Vacuum instruments for the analysis of surfaces Introduction Ellipsometry Electron diffraction (LEED and HEED) Auger electron spectroscopy (AES) Scanning electron microscopy (SEM) Electron microprobe Electron spectroscopy for chemical analysis (ESCA) Photoelectron spectroscopy Ion scattering spectrometer Ion scattering microscope Secondary ion mass spectrometer (SIMS) Static SIM Ion imaging (SIM) Secondary ion microprobe 365 References Ion impact sputtering: particle emission related to apparatus design and thin fj.1m growth Introduction Physical sputtering Basic types of sputtering system

7 viii - CONTENTS Factors influencing film growth and deposition rate Vacuum system design and partial pressure monitoring References Manufacturers' Index Equipment Index Subject Index Advertisers'Index page

8 Introduction Vacuum apparatus is widely used in research and industrial establishments for providing and monitoring the working environments required for the operation of many kinds of scientific instruments and process plant. The vacuum conditions needed range from the relatively coarse vacuum requirements in applications covering diverse fields such as food packaging, dentistry (investment casting), vacuum forming, vacuum metallurgical processes, vacuum impregnation, molecular distillation, vacuum drying and freeze drying etc. to the other extreme involving the highest possible vacuum as in particle accelerators, space technology - both in simulation and outer space, and research studies of atomically clean surfaces and pure condensed metal films. Vacua commence with the rough vacuum region, i.e. from atmosphere to 100 Pa * passing through medium vacuum of 100 Pa to 0 1 Pa and high vacuum of 0 1 Pa to 1 J.lPa (10-6 Pa) until ultra high vacuum is reached below 1 J.lPa to the limit of measurable pressure about I ppa (10-12 Pa). Two decades ago it was possible for a vacuum scientist or engineer to have a comprehensive knowledge of the operating principles, characteristic and chief manufacturers of the pumps, instruments and plant used in his field. Since then a whole family of new types of vacuum pump and analytical and process monitoring instruments have been developed and passed into routine manufacture. Also the ultra high vacuum region has been entered and new vacuum techniques have appeared often requiring use of vacuum systems, on an industrial scale. There are now many companies concerned with the production of basic vacuum components, such as pumps and instruments, and their related accessories. If it has become difficult for the vacuum worker to maintain an overall view of his field then obviously it is even more so for those who regard vacuum apparatus as tools or a means to an end. Fortunately reference works are available reviewing most aspects of vacuum technology and its applications but there are no major works cataloguing the types and makers of * The pascal CPa) is the SI unit of pressure: 1 Pa = 1 N/m2, although currently the Torr is still the most widely used pressure unit in vacuum technology. 100 Pa = 3/4 Torr approximately (1 Pa = mtorr, 1 Torr = Pa). Wherever possible the SI unit of pressure has been used in the handbook but conversion of many of the graphs and tables reproduced has not always been possible. Also, there are many fields where vacuum pressure is only an indicator of satisfactory or adverse working conditions and there is no immediate incentive to adopt the base unit. ix

9 x - INTRODUCTION available vacuum products except for occasional exhibition catalogues which are limited by participation. The handbook presented here corrects the foregoing deficiency by giving classified information about the performance and characteristics of the pumps, instruments and process plant available from manufacturers all over the world. It also relates their characteristics and performance to basic vacuum data which can be applied in system design and uses. The data sections give information on: gas flow under viscous and molecular flow conditions, gas permeation through and desorption from vacuum materials and the properties of pump fluids, sealing compounds and greases. Finally, it was considered desirable to present the reader with reviews on selected topics on vacuum attainment, instrumentation and application for which recent advances had been made. By this means parity is maintained between treatment of new products in these fields and knowledge of their function. The authors and publisher express their thanks to the many manufacturers and research centres who have kindly supplied information on which much of the product and basic vacuum data given here is based. Furthermore, comments, criticisms and suggestions for additions from manufacturers and users alike are welcomed to ensure the comprehensive nature of future editions of this handbook. We would like to express our appreciation for the help given by Jean Charman, Jennifer Roberts and Norma Ward, in the preparation of the manuscript. March 1973 L. Holland, W. Steckelmacher and J. Yarwood