Dr Falk Braunschweig

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Formerly of Alcatel Vacuum Technology, Pfeiffer Vacuum
Wertheim, Germany


Book review ‘Vacuum Science and Technology’

Authors: Bert Suurmijer, Theo Mulder, Jan Verhoeven

Release date: February 2016

The fundamentals of vacuum science have already been worked out since the 17th and basic techno­logy during the first decades of the 20th century. So the knowledge about vacuum should have spread to those interested in the subject by means of a selection of books already on the market. So why would we need a new textbook on Vacuum Science and Technology?
Those who have studied science and technology might have experienced situations when they were stuck at an incomprehensible subject which suddenly fell into place when they read about it in another textbook. So a new book offering different views is always welcome. Moreover vacuum technology is continuously spreading into new applications which in turn require adaptations of existing devices and the development of new products. A comprehensive textbook on vacuum needs to take this evolution into account. The reader will therefore appreciate a new book offering the state-of-the-art as it guides him to contemporary knowledge directly applicable in research and industrial working environments.
In the preface of Vacuum Science and Technology (VST) the authors sum up in detail the evolution of the originally in Dutch language published textbook Basisboek Vacuümtechniek. For those who know the predecessor and contemplate to buy the new book a valuable read to aide their decision. The transition from Dutch to English language might be a little hardship for Dutch readers but the authors have chosen an easy to read style which makes the book attractive for a wide range of non native English speakers.
The table of contents unfolds the whole spectrum of vacuum science and vacuum technology, well organized in ten comprehensive chapters. The first three thereof comprise the physics from the basic concepts of gases to their interaction with solid enclosures and to flow phenomena. The next four chapters cover vacuum generation and measurement while the last three are dedicated to the fine art of constructing, operating and maintaining vacuum systems. The book comes along in a generous format with an easily readable text, well arranged formulae, and ample diagrams and figures. The latter partly in colour.
The first three chapters provide the fundamentals of physics for the understanding of vacuum technology. After a brief yet very interesting historical introduction into vacuum the physical basics from atoms and molecules to the states of matter lead to the kinetic theory of gases. Soon the first maths with integrals appear. However, readers mostly interested in the practical work with vacuum systems should not be scared off by differential equations and integrals as they flip through the pages. The book is for them as well as for those who want to dig deeper into the fundamentals of gas physics. The more theoretical paragraphs are clearly marked by a vertical bar at the margin of the page. Omitting these sections will not hinder comprehension of subsequent chapters. Formulae referenced consecutively are numbered for easier look-up. As these numbers include the chapter where the formula appeared in the text, the impression of the chapter number on the header or footer would be very helpful and should be considered for a future revision of the book.
Readers not bothering with the carefully laid-out mathematical derivations can skip the marked sections and will soon learn the basics of vacuum: pressure, ideal gas law, mean free path, vapour pressure. Valuable practical advice is given during the discussion of derived formulae, e.g. on temperature dependence of pressure measurements by specific vacuum gauges (equation 1.26 and 1.85). Those who have to deal with high and ultra-high vacuum (HV and UHV) will benefit from the thorough presentation of gas-solid interactions in chapter two. Especially the schematic pressure vs time curve (fig 2.18) with its “1 year” bar is worth contemplating by anyone who has to achieve UHV in a vacuum system on a production floor. The vacuum physics part of the book is completed by the third chapter on flow of gases trough tubes and orifices. Here the tools for the vacuum engineer’s day-to-day work are derived and discussed: the concepts of throughput, conductance, and pumping speed in the various flow regimes. Easy to use formulae for gases in general and specially for air at room temperature are given not only for circular but also for rectangular tube sections. A simple vacuum chamber/tube/pump system serves as an example to calculate the achievable pressure using the formulae of the preceding pages. Eleven exercises related to real life invite the reader to become familiar with calculations of vacuum systems. Thirty years of experience in the vacuum business have shown the formulae presented in this chapter yield results of sufficient precision for practical work. The application of sophisticated layout software for vacuum systems rarely give significantly improved results. So students should embrace this chapter for quick-and-dirty layout considerations and judge­ment of existing vacuum systems.
A veritable encyclopaedia is chapter four of the book. On over 200 pages the contemporary available vacuum pumps are presented, their working principles explained, typical data given, and applications discussed. All in detail and mostly illustrated with cutaway views of commercially available pumps. Most readers will not be interested in the entire range of pumps so might start with the introduction and definition paragraphs and continue with the section on pump selection at the end of the chapter. Here not only the vacuum requirements for typical applications are discussed but also the often more important requests for non vacuum aspects like secure and economic operation. Based on the knowledge of these valuable sections the pump(s) under consideration should then be studied in detail.
The next chapter is dedicated to pressure measurement. To be accurate: total pressure measurement as partial pressure measurement is discussed in a separate chapter. The broad range of com­mercially available vacuum gauges is presented, the operating principles derived from physical considerations, and the range and limits of operation are discussed. The collection even includes gauge designs which never went into production, disappeared from the market or are barely used in niche applications. A telegram style summary concludes the discussion of every gauge (measuring range, pressure reading, classification). Unlike for pumps no handy “gauge selection” chapter is provided. The reader has to check the diagram of pressure ranges given in the introduction to the pressure measurement chapter to select potential candidates for his application. He then should consult directly the individual paragraphs dealing with pros and cons of the selected gauges. The workhorses of vacuum measurement (Pirani, hot and cold ion gauges) are well covered in the book, with all the nasty traps users could slump into when they believe the convincing digital readout of their gauges. No explicit accuracy comparison of different gauge types is presented although there is sometimes much confusion among users, especially with capacitance gauges (usually linear output) and Pirani/ion gauges (usually logarithmic output). Those dedicated to run high and ultra high vacuum systems should spend the time to solve the well chosen exercises at the end of this chapter as they will sharpen senses to avoid the traps.
The title of the next chapter points to what partial pressure measurement is all about: analysis of the residual gas in a vacuum system. The authors confine themselves to three types of ion filters: sector-field, quadrupole, and ion-trap. A wide range of ion sources and ion detectors are explained together with their fields of application and pressure range limits. The important concept of the mass filter’s resolution and the interpretation of mass spectra are thoroughly discussed. The chapter gives a very good introduction to residual gas analysis and the authors do not hide the fact that understanding mass spectra may require hard work and a lot of experience.
After pumps and gauges are introduced a short chapter addresses specific measurements to qualify vacuum pumps. It is intended to give just a glimpse of these kind of measurements and in fact, bespoken specs agreed between a supplier of a vacuum pump and a customer might involve considerably more detailed measuring procedures.
The chapter on leak detection offers a broad overview of leak detection methods. Not only those usually applied in vacuum technology but also the full range of methods employed in industrial applications are presented. The most common tracer gases helium and hydrogen with the respective detectors mass spectrometer, quartz window, and MOSFET sensor are discussed as well as configurations of leak detector pumping systems. Practical advice on leak detection and leak finding on vacuum systems, also with the aid of gas type dependent total pressure gauges renders this chapter a valuable guide for daily work with vacuum installations in research and industry.
The next chapter deals with all the other components which make up a vacuum system together with pumps and gauges: tubing elements with their standard flanges, feedthroughs, and a wide variety of valves. Also joining techniques and sealing elements, both elastomeric and metallic are discussed in great detail. Even the operating principle of a mass flow controller, often used with vacuum systems but rarely discussed in vacuum text books, is presented in conjunction with dosing valves.
Materials and their properties with regard to vacuum applications and the associated working techniques are the subject of the last chapter. The authors present a plethora of information mainly on gas evolution from solid materials and about good working practices. The book is completed by annexes of useful tables, diagrams and vacuum symbols. A handy glossary of materials follows, each entry stating the main data and properties for vacuum use including information like the vapour pressure, which sometimes is difficult to find. The book is completed by the answers to the exercises and an extensive index.
After studying Vacuum Science and Technology the initial question why we need a new book on vacuum can be answered: Yes we need a book with the latest developments in pumps and gauges. Yes we need a book dedicated to Pascal as a SI unit (maybe in a future revision also amu will be replaced by up-to-date u). Yes we need a book like VST – easy to read and to comprehend.

FB 12-11-2018

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