Vacuum

261 Pages·1998·17.297 MB·English

VACUUM
SCIENCE,
TECHNOLOGY
AND
APPLICATIONS

VACUUM
SCIENCE,
TECHNOLOGY
AND
APPLICATIONS
Pramod K. Naik
CRC Press
Taylor & Francis Group
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Contents v
Contents
About the Author xi
Preface and Acknowledgements xii
Introduction xv
1. Kinetic Theory of Gases 1
1.1 Basic Concepts 1
1.1.1 Pressure 1
1.1.2 Equation of State 2
1.1.3. Gas Density 2
1.1.4 Avogadro’s Law 3
1.1.5 Molecular Motion and Energy 4
1.1.6 Molecular Impingement Rate 4
1.1.7 Mean Free Path 5
1.1.8 Heat Transfer 5
1.1.8.1 Heat Transfer by Radiation 5
1.1.8.2 Heat Transfer by Conduction at Low Pressure 6
1.1.8.3 Convection 7
1.1.9 Thermal Transpiration 8
2. Flow of Gas and Conductance 10
2.1 Types of Gas Flow 10
2.1.1 Viscous Flow 10
2.1.2 Molecular Flow 12
2.2 Conductance 13
2.2.2 Conductance in the Viscous Flow Region 16
2.2.3 Conductance in the Transition Flow Region 18
2.3 Basic Pumping Equation 21
2.4 Standard Leaks 21
2.5 Rise of Pressure in a Sealed-off Vacuum Device 22
3. Surface Phenomena 24
3.1 Neutrals–Surface Interactions 24
3.1.1 Diffusion of Gases 24
3.1.2 Permeation 25
3.1.3 Physical and Chemical Adsorption 26
3.1.3.1 Monolayer 28
vi Contents
3.1.3.2 Sticking probability 28
3.1.3.3 Adsorption Isotherms and Surface Area 30
3.1.4 Desorption 32
3.1.4.1 Determination of Activated Energy of Desorption 35
3.1.4.2 Photon–Electron and Ion-Induced Desorption 37
3.1.5 Thin Films Deposition on Surfaces 37
3.1.6 Molecular Beam Epitaxy (MBE) 39
3.1.7 Surface Ionization 39
3.2 Interaction of Charged Particles, Radiation and Heat
with Solid Surfaces 41
3.2.1 Ion–Surface Interactions 41
3.2.1.1 Scattering of Positive Ions 42
3.2.1.2 Secondary Electron Emission by Ion Surface Interaction 43
3.2.1.3 Entrapment of Injected Ions 44
3.2.1.4 Sputtering 45
3.2.1.5 Ion Beam Implantation 47
3.2.1.6 Ion Beam Deposition/Ion Plating 48
3.2.2 Electron–surface interactions 48
3.2.2.1 Secondary Electron Emission by Electrons 49
3.2.2.2 Auger Electron Emission 50
3.2.2.3 X-ray Emission 51
3.2.2.4 Interaction of High Energy Electrons with Surface 52
3.2.3 Photon–surface interactions 53
3.2.3.1 Photoelectric Emission 53
3.2.3.2 X-Ray Photoelectron Emission 53
3.2.4 Electric Field–Surface Interaction 54
3.2.4.1 Field Emission 54
3.2.5 Thermionic Emission 55
3.2.6 Emission From Contact Surfaces in Vacuum Arcs 56
3.2.7 Evaporation–Sublimation–Vapour Pressure 56
3.2.8 Vacuum Evaporation 57
4. Interaction of Neutrals, Charged Particles and Radiation
with Gases in Vacuum 62
4.1 Disassociation, Excitation and Ionization 62
4.1.1 Mean Free Path of Electrons and Ions 63
4.1.2 Ionization Potential and Ionization Efficiency/Cross
Section 63
4.1.3 Positive Ion-Impact Ionization 64
4.1.4 Ionization by Photons and Thermal Ionization 64
4.1.5 Deionization 65
4.2 Electrical Breakdown in Vacuum 65
4.2.1 Gas Breakdown 66
4.2.2 Glow Discharge 70
4.2.3 Vacuum Breakdown 70
4.3 Plasma 72
Contents vii
5. Measurement of Pressure 74
5.1 Mechanical Gauges 74
5.1.1 Manometers 74
5.1.2 McLeod Gauge 76
5.1.3 Diaphragm gauges 77
5.1.4 Knudsen Gauge 78
5.1.5 Bourdon Gauge 79
5.2 Thermal Conductivity-based Gauges 79
5.3 Ionization Gauges 81
5.3.1 Hot Cathode Ionization Gauges 82
5.3.1.1 Schulz and Phelps Gauge 82
5.3.1.2 Conventional Hot Cathode Ionization Gauge 83
5.3.1.3 Bayard–Alpert Gauge 84
5.3.1.4 Modulated Bayard–Alpert Gauge 87
5.3.1.5 Extractor Gauge 88
5.3.1.6 Magnetron Gauge 88
5.3.1.7 Helmer Gauge 90
5.3.1.8 Helmer Gauge–180° Ion Deflection 90
5.3.1.9 Axial Symmetric Transmission Gauge 91
5.3.1.10 Orbitron Gauge 92
5.3.2 Cold Cathode Ionization Gauges 94
5.3.2.1 Penning gauge 94
5.3.2.2 Magnetron and inverted magnetron gauges 95
5.4 Partial Pressure Gauges 96
5.4.1 Magnetic Sector Mass Spectrometer 97
5.4.2 Omegatron 99
5.4.3 Quadrupole Mass Analyzer 100
5.4.4 Time-of-Flight (TOF) Mass Analyzer 101
5.4.5 Detectors 103
5.4.6 General Discussion on Residual Gas Analyzers 103
6 Vacuum Pumps 107
6.1 Positive Displacement Pumps 107
6.1.1 Water-Ring Pump 107
6.1.2 Rotary Vane Pump and Rotary Piston Pump 108
6.1.3 Turbo-molecular Pump 113
6.1.4 Roots Pump 117
6.1.5 Diaphragm Pump 118
6.1.6 Screw, Scroll and Claw Pumps 119
6.1.7 Diffusion Pump 121
6.1.8 Vapour Booster Pump 125
6.2 Pumps Using Conversion of Gas into Solid Phase 126
6.2.1 Getter Pumps 126
6.2.1.1 Bulk Getters 127
6.2.1.2 Flash and Evaporable Getters 129
viii Contents
6.2.2 Getter-Ion Pump 133
6.2.3 Sputter-Ion Pump 135
6.2.3.1 Normal Diode Pump 136
6.2.3.2 Stabilized Diode Pumps 139
6.2.3.3 Triode Pump 141
6.2.3.4 Integrated Linear Pumps 141
6.2.3.5 Pressure Range and Operational Aspects 142
6.2.4 Cryogenic Pumps 142
6.2.4.1 Cryo-condensation Pumping 143
6.2.4.2 Cryo-Sorption Pumps 146
6.2.4.3 Pumping by Cryo-Trapping 150
6.2.4.4 Types of Cryo-Pump 151
7. System Design 154
7.1 Selection of Pumps 155
7.2 Pumping Process and Pumpdown 157
7.2.1 Pumpdown Time 160
7.3 Symbolic Diagrams 163
8. Vacuum Measurement Methods 167
8.1 Pumping Speed Measurements 167
8.2 Calibration of Gauges 171
9. Vacuum Materials, Hardware, Fabrication Techniques,
Cleaning Processes and Surface Treatment 172
9.1 Couplings and Flanged Joints 172
9.2 Hoses and Bellows 174
9.3 Vacuum Valves and Traps 175
9.4 Mechanical Manipulators for Vacuum 177
9.5 Glass-to-Metal Seals 177
9.6 Ceramic-to-Metal Seals 179
9.7 Fabrication Techniques 181
9.7.1 Soldering and brazing 182
9.7.2 Vacuum brazing 183
9.7.3 Welding 184
9.7.4 Electron Beam Welding 185
9.8 Cleaning 186
9.8.1 Mechanical cleaning 187
9.8.2 Chemical Cleaning 187
9.8.3 Electrochemical Cleaning 188
9.8.4 Ultrasonic Cleaning 188
9.8.5 Thermal Cleaning Processes 189
9.8.6 Commonly used cleaning chemicals 189
9.8.7 Clean Rooms 191
Contents ix
10. Leak Detection 193
10.1 Methods using Pressurization 193
10.2 Methods using Evacuation 194
10.3 Leak Detector Calibration 197
11. Extreme High Vacuum 198
11.1 Factors Governing Ultrahigh and Extreme High Vacuum 198
11.2 Pumps for XHV 200
11.3 Gauges for XHV 201
11.4 Reduction of Outgassing 201
12. Applications 206
12.1 General 206
12.2 Surface Analysis 207
12.2.1 Ion Scattering Spectroscopy 207
12.2.2 Secondary Ion Mass Spectrometry 209
12.2.3 Auger Electron Spectroscopy 210
12.2.4 Electron Spectroscopy for Chemical Analysis 212
12.2.5 Low Energy Electron Diffraction and Reflected High
Energy Electron Diffraction 213
12.2.6 Electron Microscopy 216
12.2.6.1 Scanning Electron Microscope 216
12.2.6.2 Transmission Electron Microscope 218
12.2.6.3 Reflection Electron Microscope 219
12.2.6.4 Scanning Transmission Electron Microscope 219
12.2.6.5 Field Emission Microscope 219
12.2.6.6 Field Ion Microscope 220
12.3 Space Simulation 222
12.4 Gravitational Waves 224
12.5 Vacuum Furnaces 224
12.6 Particle Accelerators 227
12.7 Plasma Applications 230
12.7.1 Plasma Fusion Machines 230
12.7.2 Vacuum Plasma Spraying 231
12.8 Thin Films Applications 232
12.9 Vacuum Interrupters 234
12.10 Recent Advances 236
Index 239