Contents

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Contents chapter 1

Basic concepts

1.1        Introduction 1
1.2        Historical overview 2
1.3        Molecules and atoms 5
1.4        Physical states of matter 8
1.5        Kinetic theory of gases 9
1.6        Molecular velocities and energies 10
1.7        Pressure of a gas 16
1.8        Ideal gas law 20
1.9        Dalton’s law 21
1.10      Avogadro’s law; equation of state for an ideal gas 21
1.
11      Van der Waals equation of state 23
1.12      Mean free path 25
1.13      Rate of incidence of gas particles on a surface 30
1.14      Energy flow to a wall 32
1.15      Vapour pressure; evaporation rate of 34
1:16      Transport phenomena in gases 36
1.
17      Transportation of a physical quantity in a viscous gas G 37
1.
18      Viscosity 40
1.18.1   Viscosity in a dense gas (Kn «1) 40
1.18.2   Viscosity in a rarefied gas (Kn »1) 42
1.19      Thermal transpiration (thermo-molecular flow) 45
1.
20      Thermal conductivity 46
1.20.1   Thermal conductivity at high pressures (Kn «1) 46
1.20.2   Thermal conductivity at low pressures (Kn »1) 50
1.21      Diffusion of gases 54
1.21.1   Fick’s diffusion laws 54
1.21.2   Self-diffusion 55
1.21.3   Diffusion in gas mixtures 57
exercises

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Contents chapter 2

Gas-solid interaction

2.1      Introduction 63
2.2      Physical adsorption 63
2.3      Why no mirror reflection at a solid surface? 65
2.4      Lennard-Jones potential 67
2.5      Rate of adsorption 71
2.6      Residence time 71
2.7      Rate of desorption 73
2.8      Adsorption-desorption equilibrium 75
2.9      Adsorption isotherms 76
2.9.1   Monolayer (Langmuir) adsorption 76
2.9.2   Multilayer (BET) adsorption 78
2.10    Surface migration; mobile versus localized adsorption 81
2.11    Porous materials; persorption 82
2.12    Chemisorption 85
2.13    Condensation 89
2.14    Absorption, diffusion and permeation 90
2.15    Outgassing 97
exercises

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Contents chapter 3

Flow of gases through tubes and orifices

3.1       Introduction 101
3.2      Thermodynamic laws 104
3.2.1   First law of thermodynamics 104
3.2.2   Second law of thermodynamics; isentropic process 107
3.2.3   Equation of state 107
3.3      Overview of flow laws 109
3.3.1   Continuity equation 109
3.3.2   Bernoulli’s law 111
3.3.3   Conservation of momentum 115
3.4      Supersonic flow through a nozzle or aperture 116
3.5      The shock wave 123
3.6      Laminar flow 129
3.7      ‘Choked’ gas flow in a tube 133
3.8      Molecular flow 134
3.8.1   Molecular flow through an orifice 135
3.8.2   Molecular flow in a (cylindrical) tube 136
3.9      Definition of the concept of ‘conductance’ 139
3.10    Conductance in case of a supersonic flow 140
3.11    Conductance in case of a laminar flow 141
3:12    Conductance in the case of a choked flow 144
3.13    Conductance in case of a molecular flow 144
3:14    Conductance in the transition domain between viscous and molecular flow 152
3.15    Conductance of complex vacuum components 153
3:16    Pumping speed 153
17.3    Calculation examples in a simple vacuum system 155
exercises

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Contents chapter 4

Vacuum pumps and pumping systems

4.1      Introduction 160
4.2      Definitions 163
4.3      Compression processes in transfer pumps 166
4.4      Liquid-sealed rotary pumps 168
4.4.1   Liquid ring pump 168
4.4.2   Rotary vane pump 175
4.4.3   Gas ballast 181
4.4.4   Oil-sealed multivane pump 189
4.4.5   Rotary-piston pump 190
4.4.6   Oil-sealed rotary pumps in practice; pump accessories 193
4.5      Liquid jet pump 198
4.6      Vapour-stream pumps 199
4.6.1   Steam jet pump 208
4.6.2   Diffusion pump 211
4.6.3   Pump fluids 223
4.6.4   Diffusion pump system operation 225
4.6.5   Hints and safety measures for diffusion pump systems 228
4.6.6   Vapour booster pump 229
4.7      Oscillation pumps 230
4.7.1   Piston pump 231
4.7.2   Diaphragm pump 233
4.8      Dry rotary pumps 235
4.8.1   Side channel blower 235
4.8.2   Oil-free multivane pump 239
4.8.3   Scroll pump 240
4.8.4   Roots pump 243
4.8.5   Claw pump 260
4.8.6   Screw pump 268
4.9      Molecular pumps 270
4.9.1   Molecular drag pump (MDP) 272
4.9.2   MDP/side channel pump 280
4.9.3   Turbo molecular pump (TMP) 285
4.9.4   Design and engineering aspects of turbo molecular pumps 293
4.9.5   Turbo molecular pump system operation 301
4.9.6   Hybrid molecular pump (HMP) 303
4:10     Capture pumps 307
4.10.1  Sorption pump 308
4.10.2  Getter pump 318
4.10.3  Sputter-ion pump 325
4.10.4  Cryopump 335
4.10.5  Cryopump system operation 348
4:11      Pump selection 351
4.11.1  Quantity of gas (throughput) Q to be pumped 351
4.11.2  Desired operating pressure p 352
4.11.3  Required pumping speed S 353
4.11.4  Economic aspects 353
4.11.5  Pumping aggressive, toxic or explosive gases and vapours 354
4.11.6  Pumping large amounts of gas 356
4.11.7  Obtaining ultra-high vacuum 358
exercises

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Contents chapter 5

Pressure measurement

5.1      Introduction 367
5.2      Absolute gauges 370
5.2.1   U-tube manometer 370
5.2.2   McLeod manometer 373
5.2.3   Knudsen gauge 377
5.3      Mechanical (aneroid) gauges 384
5.3.1   Bourdon gauge 385
5.3.2   Capsule dial gauge 387
5.3.3   Diaphragm vacuum gauge 388
5.3.4   Piezoresistive pressure gauge 389
5.3.5   Capacitance gauge 392
5.4      Viscosity gauges 396
5.4.1   Spinning rotor gauge 396
5.4.2   Quartz crystal friction gauge 401
5.5      Heat conductivity gauges 404
5.5.1   Principle and operation 404
5.5.2   Configurations and measuring methods 411
5.6      Hot cathode ionization gauges 416
5.6.1   Principle and operation 416
5.6.2   Properties 424
5.6.3   Configurations 431
5.7      Cold cathode ionization gauges 438
5.7.1   Principle and operation 438
5.7.2   Properties 443
5.7.3   Configurations 445
exercises

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Contents chapter 6

 Partial pressure gauges and residual gas analysis

6.1    Introduction 452
6.2    The ion source 454
6.3    The mass analyzer section; resolution 460
6.4    180° magnetic deflection mass spectrometer 465
6.5    Quadrupole mass spectrometer 472
6.6    Autoresonant trap mass spectrometer 480
6.7    The ion collector; electron multipliers 486
6.8    Interpretation of residual gas spectra 490
6.9    Spectrum analysis 494
6.10  Spectra or vacuum systems 498
exercises

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Contents chapter 7

Measurements of pump properties

7.1     Introduction 506
7.2     Measurement of ultimate pressure 506
7.3     Pumping speed measuring procedures 508
7.3.1  Constant volume method 508
7.3.2  Constant pressure method 511
7.4     Measurement of the pumping speed of a (ultra-)high vacuum pump 515
7.5     Measurement of the pump’s compression ratio 517
exercises

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Contents chapter 8

Leak detection

8.1      Introduction 520
8.2      Conceptual considerations; leak rate 521
8.3      Leak detection methods 523
8.3.1   Pressurizing (inside-out) methods 524
8.3.2   Reduced pressure (outside-in) methods 526
8.3.3   Atmosphere method versus bombing 529
8.4      The use of helium as a tracer gas 532
8.5      Reviewing the symptoms; troubleshooting 535
8.6      Leak testing and leak finding 537
8.7      Helium leak detectors 538
8.7.1   The mass spectrometer 538
8.7.2   The pumping system 540
8.7.3   Response time 543
8.7.4   Sensitivity 546
8.7.5   Reference leak 548
8.8      Leak detection by vacuum gauge or RGA 549
8.9      Inside-out sniffing systems 552
8.9.1   Helium sniffer 552
8.9.2   Hydrogen leak detector 553
8.9.3   Quartz window sensor 555
8.9.4   Halogen leak detector 556
8.9.5   Multigas sniffing systems 558
8.10    Leak detection of (ultra-)high vacuum systems 559
exercises

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Contents chapter 9

Sealing techniques and system components

9.1       Introduction 575
9.2       Demountable joints 575
9.2.1   Grooved flanges with elastomer sealing 576
9.2.2   The Pneurop standard flange system 580
9.2.3   Metal seals 581
9.2.4   Flange constructions for metal sealing 581
9.3      Permanent sealing techniques 584
9.3.1   Welding 584
9.3.2   Brazing and soldering 588
9.3.3   Glass-to-metal and ceramic-to-metal seals 591
9.3.4   Gluing 592
9.4      Vacuum feedthroughs 593
9.4.1   Electrical feedthroughs 593
9.4.2   Motion feedthroughs 594
9.4.3   Manipulator systems 598
9.4.4   Liquid feedthroughs 598
9.4.5   Optical windows 599
9.5      Vacuum valves 599
9.5.1   Sealing constructions 600
9.5.2   Actuation mechanisms 603
9.5.3   Configurations 604
9.6      Fine control gas admission systems 607
9.6.1   Needle valves 607
9.6.2   Bakeable UHV precision dosing valves 608
9.6.3   Permeation valves 609
9.6.4   Mass flow controllers 611
9.7      Bellows 612
9.7.1   Corrugated bellows 612
9.7.2  Diaphragm bellows 613

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Contents chapter 10

Material selection, lubrication, cleaning,
working discipline

10.1       General considerations on the selection of materials 614
10.2       Vacuum properties of materials 615
10.3       Surface outgassing 618
10.4       Bulk outgassing 619
10.5       Measurement of outgassing rate 620
10.6       Permeability 622
10.7       Vapour pressure of materials 625
10.8       Decomposition of materials 630
10.9       Summary of outgassing phenomena 632
10.10     Specific selection criteria for metals and alloys 634
10.11     Specific selection criteria for glasses 638
10.12     Specific selection criteria for ceramics 639
10.13     Specific selection criteria for synthetic materials 641
10.14     Lubrication in vacuum 646
10.14.1  Dry lubrication 647
10.14.2  Wet lubrication 648
10.15     Cleaning procedures 649
10.15.1  Bulk outgassing 649
10.15.2  The ‘physical’ surface 649
10.15.3  Surface contamination 650
10.15.4  Adsorbed gases and vapours 653
10.16     General rules for working with vacuum systems 655
10.16.1  What’s clean should be kept clean 655
10.16.2  Pumping procedures 656
10.16.3  Operating errors and malfunctions 657

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Appendices

Appendix A: Units and Symbols 659

SI base units
SI derived units
Some unit conversion factors
Prefix for decimal multiples and submultiples of SI units

Appendix B: Tables and diagrams 663

Important constants
Periodic table of the elements
Greek alphabet
Conversion factors for pressure units
Conversion factors for throughput (flow rate)
Conversion factors for pumping speed (volumetric flow rate)
Physical properties of some gases
Vapour pressure and density of saturated water vapour in the temperature range 0-100 °C
Technical data of some diffusion pump oils
Components of atmospheric air
Graph of air pressure and temperature as a function of the altitude above the earth’s surface
Composition of air as a function of the altitude above the earth’s surface

Appendix C: ISO symbols for vacuum components 678

Appendix D: Properties and applications of materials in vacuum 683

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Index

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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