Chapter One The Nature of Vacuum 1
1.1 What Is Vacuum? 1
1.2 General Nature of a Gas 1
1.3 The Atmosphere 4
1.4 Units of Pressure 7
1.5 Decimals and Powers of Ten 9
1.6 Degrees of Vacuum 11
1.7 Mean Free Path of a Gas 11
1.8 Temperature Scales 13
1.9 Effect of Pressure on a Gas 15
1.10 Effect of Temperature on a Gas 17
1.11 The General Gas Law 19
1.12 Some Other Characteristics of Gases 21
Chapter Two Vacuum Systems 23
2.1 Elements of a Vacuum System 23
2.2 Some Types of Vacuum Systems 25
2.3 Quantity of Gas and Throughput 26
2.4 Comparison with an Electric Circuit 28
2.5 Comparison with Water Flow 30
2.6 Resistances Connected in Series 31
2.7 Resistances Connected in Parallel 34
2.8 The Use of Logarithms 36
2.9 Logarithmic Scales 37
2.10 Pumping Speed 41
2.11 Losses in Pumping Speed 42
Chapter Three Rotary Oil-Sealed Pumps 49
3.1 The Nature of Such Pumps 49
3.2 Pump Oils and the Oil System 50
3.3 Ultimate Pressure 52
3.4 Pumping Speed 53
3.5 Effect of Connecting Lines 56
3.6 Pump Size and Pump-Down Time—Method 1 62
3.7 Pump Size and Pump-Down Time—Method 2 65
3.8 Pump Size and Pump-Down Time—Method 3 67
3.9 Gas Handling Capacity of a Pump 69
3.10 Some General Rules 70
3.11 Setting Up Rotary Oil-Sealed Pumps 70
3.12 Starting Rotary Oil-Sealed Pumps 72
3.13 Stopping Rotary Oil-Sealed Pumps 72
3.14 Maintenance Problems 73
3.15 Use of a Nomograph 76
Chapter Four Vapor Pumps 77
4.1 General Nature of Vapor Pumps 77
4.2 Some Features of Diffusion Pumps 79
4.3 Some Features of Ejector Pumps 84
4.4 Mercury versus Oil 87
4.5 Pump Performance 89
4.6 Performance Characteristics of Diffusion Pumps 92
4.7 Performance Characteristics of Ejector Pumps 98
4.8 Migration of Pump Fluid 98
4.9 Backing Pump Requirements 100
4.10 Effect of Connecting Lines 101
4.11 Pump-Down Time for Vapor Pumps 103
4.12 Operating a Vapor Pump 104
4.13 Poor Operation or Failure of Vapor Pumps 105
Chapter Five Some Other Types of Pumps 109
5.1 Molecular Drag Pumps 109
5.2 Roots Blower Pumps 113
5.3 The Use of Getters as Pumps 117
5.4 Gettering and Ionizing 122
5.5 Pumps Using Evaporation and Ionization 124
5.6 Pumps Using Sputtering and Ionization 125
5.7 Cryopumping 132
5.8 Other Sorption Pumps 138
5.9 Water Aspirator,Toepler,and Sprengel Pumps 139
Chapter Six Measurement of Pressure 142
6.1 The Nature of Vacuum Gauges 142
6.2 Bourdon and Diaphragm Gauges 143
6.3 U-Tube Manometers 146
6.4 McLeod Gauges 150
6.5 Pirani and Thermocouple Gauges 162
6.6 Thermionic Ionization Gauges 168
6.7 Cold Cathode Ionization Gauge 176
6.8 Gauges Using Radioactive Materials 181
6.9 Viscosity- and Radiometer-Type Gauges 184
6.10 Use of Discharge Tube to Measure Pressure 187
6.11 Gauges to Measure Very Low Pressures 190
6.12 Calibration and Ranges of Vacuum Gauges 193
Chapter Seven Measurement of Pumping Speed 198
7.1 Why Measure Pumping Speed? 198
7.2 The Metered-Leak Method 199
7.3 Positioning of Vacuum Gauge and Air Leak 201
7.4 Admission of Air 202
7.5 Vacuum Gauges 205
7.6 Test Dome 206
7.7 Rate-of-Rise Measurement 207
7.8 Use of a Known Conductance 211
Chapter Eight Properties of Some Vacuum Materials 216
8.1 The Elements 216
8.2 Mercury and Water 218
8.3 Liquids Used in Vacuum Practice 219
8.4 Gases and Vapors 222
8.5 Elastomers and Some Other Materials 226
8.6 Glasses,Ceramics,and Metals Sealing to Them 233
8.7 Copper and Copper Bearing Alloys 236
8.8 Iron and Some of Its Alloys 238
8.9 Molybdenum,Tantalum,and Tungsten 240
8.10 Nickel and Its Alloys 241
8.11 Vacuum Greases,Oils,Cements,and Waxes 242
8.12 Some Drying and General Sorption Agents 249
8.13 Temperature Data 252
8.14 Alphabetical Listing 252
Chapter Nine Cleaning Techniques 262
9.1 The Nature of Contaminants 262
9.2 General Methods of Reducing Contamination 263
9.3 Descaling and Pickling Processes 266
9.4 Electrolytic Cleaning and Polishing 268
9.5 Cleaning of Mercury and Glass 271
9.6 Miscellaneous Cleaning Procedures 273
9.7 Cleaning by Degassing 274
Chapter Ten Some Fabrication Techniques 279
10.1 Glass versus Metal 279
10.2 Glass-to-Metal Seals 281
10.3 Fabrication of Some Other Types of Seals 283
10.4 Soldering 285
10.5 Brazing 288
10.6 Hydrogen Brazing 298
10.7 Welding 301
10.8 Electroplating 305
10.9 Gasketed Joints 309
10.10 Construction of Vacuum Vessels 318
Chapter Eleven Baffles,Traps,and Valves 322
11.1 The Use of Baffles and Traps 322
11.2 Some Designs of Baffles 324
11.3 Some Designs of Traps 328
11.4 Operation and Maintenance of Baffles and Traps 338
11.5 Liquid Nitrogen Filling Systems 341
11.6 Pumping Losses in Baffles and Traps 343
11.7 The Functions of Vacuum Valves 349
11.8 Gate,Disk,and Flap Valves 351
11.9 Globe,Needle,and Diaphragm Valves 356
11.10 Stopcock,Plug,and Ball Valves 359
11.11 Bakable Valves 363
11.12 Some Special Valves 367
11.13 Care and Maintenance of Valves 369
Chapter Twelve Some Other Vacuum Components 371
12.1 Common Static Seals Using Elastomers 371
12.2 Sliding and Rotating Seals 377
12.3 High Temperature Seals 383
12.4 Low Temperature Seals 388
12.5 Some Other Forms of Seals 391
12.6 Couplings,Hose Clamps,etc. 395
12.7 Electrical Lead-Throughs 398
12.8 Leak Devices and Cut-Offs 401
12.9 Protective Devices 407
Chapter Thirteen Conventional Vacuum Systems 411
13.1 The Nature of Such Systems 411
13.2 Basic Design Considerations 412
13.3 Conductances of Components 413
13.4 Designing a Vacuum System 414
13.5 Setting Up a New Vacuum System 422
13.6 Starting Up a Vacuum System 423
13.7 Starting and Operating Tight Vacuum Systems 426
13.8 Shutting Down a Vacuum System 428
13.9 Maintenance Problems with Vacuum Systems 429
13.10 The Small Vacuum Laboratory 430
Chapter Fourteen Very High and Ultra-High Vacuum Systems 433
14.1 The Nature of Such Systems 433
14.2 Small Very High Vacuum Systems 434
14.3 Small Ultra-High Vacuum Systems 436
14.4 Bake-Out Arrangement for Small Systems 440
14.5 Bake-Out Procedure for Small Systems 441
14.6 Large Low Pressure Vacuum Systems 444
14.7 Bake-Out of Large Systems 451
14.8 Construction Materials and Techniques 453
14.9 Is There a Low Pressure Limit? 454
Chapter Fifteen Finding and Repairing Leaks 456
15.1 When Is a System Tight? 456
15.2 Sizes of Leaks 457
15.3 Methods of Leak Detection 458
15.4 Sealing Substance Outside,Pressure Change Inside 460
15.5 Rate-of-Rise Measurements 460
15.6 High Pressure Inside,Indicator Outside 463
15.7 Spark Coils and Discharge Tubes 466
15.8 Probe Materials with Standard Vacuum Gauges 468
15.9 Unique Response of Vacuum Gauges 469
15.10 Halogen Leak Detectors 473
15.11 The Helium Leak Detector 474
15.12 Sensitivity of Helium Leak Detectors 475
15.13 Response and Clean-Up Times 478
15.14 Vacuum Testing 480
15.15 Pressure and Pressure-Vacuum Testing 484
15.16 Commercial Helium Leak Detectors 488
15.17 What Leak Detection System Should Be Used? 493
15.18 Some General Rules for Leak Hunting 497
15.19 Repairing Leaks 499
Appendices 503
A Quantities from Kinetic Theory of Gases 503
B Mechanical,Ejector,and Diffusion-Ejector Pump Oils 506
C Quantities and Relationships Useful in Vacuum Practice 508
D Appearance of Discharges in Gases and Vapors at Low Pressures 514
E Bibliography 515
Index 523