Fundamentals of Vacuum Technology www.leybold.com Leybold GmbH Bonner Strasse 498 D-50968 Cologne Fundamentals of Vacuum Technology

Preface Leybold GmbH being part of the globally active industrial Atlas Copco Group has developed into the world market leader in the area of vacuum technology. In this leading position we do not only recognize this as a task and a challenge but also as a responsibility with respect to our customers. This brochure shall independently of the current range of products provide an easy to read overview covering the entire area of vacuum technology. The presented diagrams and data of the products shall above all promote a deeper understanding of the underlying technological functions and are not to...

Fundamentals of Vacuum Technology

Fundamentals of Vacuum Technology revised and compiled by Dr. Walter Umrath with contributions from Dr. Hermann Adam †, Alfred Bolz, Hermann Boy, Heinz Dohmen, Karl Gogol, Dr. Wolfgang Jorisch, Walter Mönning, Dr. Hans-Jürgen Mundinger, Hans-Dieter Otten, Willi Scheer, Helmut Seiger, Dr. Wolfgang Schwarz, Klaus Stepputat, Dieter Urban, Heinz-Josef Wirtzfeld, Heinz-Joachim Zenker

Vacuum physics Quantities, their symbols, units of measure and definitions . . . . . . . . . . . . . . . . . . . . . . . 9 Basic terms and concepts in vacuum technology . . . . . . . . . . . . 9 Atmospheric air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Gas laws and models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Continuum theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Kinetic gas theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 The pressure ranges in vacuum technology and...

Table of Contents 4. Analysis of gas at low pressures using mass spectrometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.2 A historical review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.3 The quadrupole mass spectrometer (TRANSPECTOR) . . . . . . 96 4.3.1 Design of the sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 4.3.1.1 The normal (open) ion source . . . . . . . . . . . . . . . . . . . . . . . . . . 96...

Optical coatings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 Glass coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Systems for producing data storage disks . . . . . . . . . . . . . . . 137 8 Instructions for vacuum equipment operation . . . . . . . . . . 139 8.1 Causes of faults where the desired ultimate pressure is not achieved or is achieved too slowly . . . . . . . . . . . . . . . . . . 139 8.2 Contamination of vacuum vessels and eliminating contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....

Table of Contents 10.4 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 10.4.1  Basic SI units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 10.4.2  Derived coherent SI units with special names andsymbols . . 177 10.4.3   Atomic units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 10.4.4  Derived noncoherent SI units with special names and symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 11. 11.1 National and international standards and recommendations...

Quantities, their symbols, units of measure and definitions (cf. DIN 28 400, Part 1, 1990, DIN 1314 and DIN 28 402) Basic terms and concepts in vacuum technology Pressure p (mbar) of fluids (gases and liquids). (Quantity: pressure; symbol: p; unit of measure: illibar; abbreviation: mbar.) Pressure is defined in DIN Standard m 1314 as the uotient of standardized force applied to a surface and the q extent of this surface (force referenced to the surface area). Even though the Torr is no longer used as a unit for measuring pressure (see Section 10), it is nonetheless useful in the interest of “transparency”...

Vacuum physics Avogadro’s number (or constant) NA indicates how many gas particles will be contained in a mole of gas. In addition to this, it is the proportionality factor between the gas constant R and Boltzmann’s constant k: R = NA · k Derivable directly from the above equations (1.1) to (1.4) is the correlation between the pressure p and the gas density ρ of an ideal gas. In practice we will often consider a certain enclosed volume V in which the gas is present at a certain pressure p. If m is the mass of the gas present within that volume, then m ρ = --V The ideal gas law then follows directly...

throughput of this pump can be expressed with the simple equation Although it is not absolutely correct, reference is often made in practice to the “quantity of gas” p · V for a certain gas. This specification is incomplete; the temperature of the gas T, usually room temperature (293 K), is normally implicitly assumed to be known. Example: The mass of 100 mbar · l of nitrogen (N2) at room temperature (approx. 300 K) is: where S is the pumping speed of the pump at intake pressure of p. (The throughput of a pump is often indicated with Q, as well.) The concept of pump throughput is of major significance...

Vacuum physics Leak rate qL (mbar · l · s–1) According to the definition formulated above it is easy to understand that the size of a gas leak, i.e. movement through undesired passages or “pipe” elements, will also be given in mbar · l · s–1. A leak rate is often measured or indicated with atmospheric pressure prevailing on the one side of the barrier and a vacuum at the other side (p < 1 mbar). If helium (which may be used as a tracer gas, for example) is passed through the leak under exactly these conditions, then one refers to “standard helium conditions”. Outgassing (mbar · l) The term outgassing...