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Purchase Capture Pump Tecnology by Kimo M. Welch


CAPTURE PUMPING TECHNOLOGY


(Elsevier Science, Amsterdam, 2001)
Kimo M. Welch
October 2001

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Alternatively, the book may be purchased through Amazon.com.

TABLE OF CONTENTS ©
 
Page
Preface
xii
Biographical Note
xiii
Acknowledgments
xiv
1        BASIC THEORY     
1
         1.0  Introduction, Pump Classification    
1
         1.1  Pump Capacity    
1
         1.2  Understanding Pump Behavior    
1
         1.3 The Ideal Gas Assumptions    
2
         1.4  Definitions of Temperature and Pressure    
2
               The Ideal Gas Law or Equation of State    
3
               Manipulation of the Equation of State    
5
         1.5 Counting Molecules (or Atoms)    
5
         1.6 Density, Pressure and Molecular Velocities    
6
         1.7 Vapor Pressure    
8
                Surface Pumping    
11
                Pumping on a Liquid Cryogen    
12
         1.8 Mean Free Path    
12
         1.9 Thermal Conductivity of Gases    
15
                Gas Flux Incident on a Surface    
16
         1.10 Pumping Speed, a Convenient Abstraction    
17
         1.11 Throughput    
19
         1.12 Conductance, Another Convenient Abstraction    
20
               1.12.1 Conductance Model Applications    
22
                     Species and Temperature Dependence    
22
                     Pressure Dependence of Conductance    
22
                     System Geometry Dependence for Molecular Flow    
23
                     Molecular Conductance for Different Gases    
23
         1.13 Voltage, Current and Impedance Analogies    
25
                     Constructing Voltage Analogues of Complex Systems    
28
         1.14 Dalton's Law of Linear Superposition    
28
         1.15 Selective and variable Pumping Speed    
32
         1.16 Measuring Pumping Speed    
33
               1.16.1 Rate of Pumpdown    
33
               1.16.2 Single Gauge Dome Method    
36
               1.16.3 Three Gauge Method    
37
               1.16.4 Fischer-Mommsen Dome    
39
                          Three Gauge Versus Fischer-Mommsen Results    
41
                          Speed Measurement Errors Due to Trace Gas Contamination    
41
         1.17 System Diagnostics With Any Pump    
42
                          Measuring Throughput by Rate-of-Pressure-Rise    
43
         1.18 Electrical Discharges in Gases    
44
                          Ionizing Gases    
46
                          High Pressure Electrical Discharges    
46
                          Low Pressure Ionization Processes    
50
                          Ionization Gauge Sensitivities    
52
                          Partial Pressure Gauges    
53
                                Ion Collectors    
57
                                Spectra Interpretation    
57
                          Gauge Calibration Methods    
59
         1.19 Vacuum Seals    
62
                    1.19.1 Elastomer Seals    
62
                          Outgassing From Elastomers    
63
                    1.19.2 Metal Seals    
65
          1.20 Comments on Helium Leak Detection    
71
                    1.20.1 System Applications    
71
                    1.20.2 Leak Checking Systems Appended by Capture Pumps    
76
                Problem Set    
77
                References    
79
2        SPUTTERING-ION PUMPING    
83
         2.0 Introduction    
83
         2.1 The Penning Cell    
84
         2.2 I+/ P Characteristics in Penning Cells    
86
                          Qualitative I/P Characteristics    
90
         2.3 Pumping Speed Abstraction    
93
         2.4 The Making of Sputter-Ion Pumps    
94
               2.4.1 Pumping Mechanisms and Materials    
94
                          Sputtering Yield    
94
                          Physisorption and Binding Energies    
97
                          Chemisorption    
99
               2.4.2 Diode Pumps    
102
                          The Need for Clean Pumping    
102
               2.4.3 Noble Gas Instabilities    
105
                          SLAC Pump Instability Problem    
106
                          Diodes With Slotted Cathodes    
108
                          The Galaxy Pump    
109
               2.4.4 The Triode Pump    
110
                          Magnetic Fields in Diodes and Triode Pumps    
113
                          Field Emission in Triode Pumps    
114
               2.4.5 The Differential Sputtering Pump    
114
                          The High Energy Neutral Theory    
115
                          Beware of Shortcuts    
118
         2.5 Hydrogen Pumping    
119
               2.5.1 Hydrogen Pumping in Diode Pumps    
121
                          Diffusion in the Cathodes    
127
                          Titanium Cathode Material, a Model    
130
                          Ti-6Al-4V Cathode Material    
133
                          Beta-Stabilized Cathode Materials    
133
                          Diodes With Aluminum Cathodes    
134
                          Hydrogen Burial in Pump Walls    
136
                          Conclusion on Hydrogen Pumping    
137
         2.6 Triode Pumping    
138
         2.7 Transient Speed Effects    
142
         2.8 Pumping Gas Mixtures    
143
         2.9 High Pressure Operation    
145
                Advantages of Low Pressure Operation    
149
         2.10 Sputter-Ion Pumping Helium    
149
                          Regeneration After Pumping Helium    
153
         2.11 Pumping Elements Located in Antechambers or Pockets    
154
                          Distributed Sputter-Ion Pumps (DIPs)    
156
         2.12 Pump Power Supplies    
158
         2.13 Magnet Designs    
160
         2.14 More on the Nature of Penning Discharges    
164
               2.14.1 Space Charge Distribution in Penning Cells    
164
               2.14.2 More on Sputtering Patterns on Pump Cathodes    
170
                          Noise in Sputter-Ion Pumps    
171
               2.14.3 Striking Characteristics    
172
               2.14.4 Use of Very High Magnetic Fields    
173
         2.15 Other Considerations    
173
                          Maintenance and Trouble Shooting    
173
         2.16 A Summary of Advantages and Disadvantages    
175
                Appendix 2A - Electrostatic Getter-Ion Pumps    
177
                Problem Set    
179
                References    
181
3        TITANIUM SUBLIMATION PUMPING    
195
         3.0 Introduction    
195
         3.1 Sticking Coefficients    
196
         3.2 Pump Speed vs. Sticking Coefficient, a    
200
                          Titanium and Conductance Limited Operation    
203
                          Dependency of a on gas, Film Thickness and Temperature    
204
         3.3 Synthesis, Displacement and Dissociation of Gases    
208
         3.4 Sublimation Sources    
210
                          Filamentary Sources    
211
                          Constant Current Operation    
212
                          Constant Voltage Operation    
214
                          Radiantly Heated Sources    
216
                          E-Gun Sources    
218
         3.5 Combination Pumping    
220
                          Pealing of Titanium Films    
222
         3.6 Advantages and Disadvantages of TPS Pumping    
222
                Problem Set    
223
                References    
224
4        NONEVAPORABLE GETTERS (NEG)    
229
         4.0 Introduction    
229
         4.1 Mechanical Features    
229
         4.2 NEG Pumping Mechanisms    
232
                          The Pumping of CO, CO2, N2, O2    
233
                          Hydrogen Pumping    
235
                          The Pumping of Hydrocarbons    
240
                          Pumping Speeds for Gases and Gas Mixtures    
241
         4.3 Sintered NEG Structures    
246
         4.4 Advantages and Disadvantages of NEGs    
248
                Problem Set    
249
                References    
251
5       CRYOPUMPING    
255
         5.0 Introduction    
255
         5.1 Cryocondensation vs. Cryosorption    
255
               5.1.1 Cryocondensation Pumping    
257
               5.1.2 The Clausius-Claperon Equation    
258
                          Condensation at Higher Pressures    
260
               5.1.3 Thermal Transpiration    
261
               5.1.4 Adsorption Isotherms    
264
                          Classification of Adsorption Isotherms    
267
                          He and Hydrogen Isotherms on 4.2K Surfaces    
271
               5.1.5 Speed and Capacity of Cryopumps    
274
               5.1.6 Cryotrapping    
276
               5.1.7 Sieve Materials    
277
                          Plugging of Sieve Materials    
279
                          Surface Bonding of Sieve Materials    
283
         5.2 Sorption Roughing Pumps    
284
               5.2.1 Staging of Sorption Pumps    
287
                          Effects of Neon When Rough Pumping    
291
               5.2.2 Dewars and Bakeout Regeneration Heaters    
292
               5.2.3 Safety Considerations    
293
         5.3 Liquid Helium Cryopumps    
295
               5.3.1 Classification of LHe Cryopumps    
295
               5.3.2 Chevron Design    
299
         5.4 Closed-Loop Gaseous Helium Cryopumps    
301
                          Chevron Design    
303
                          Sticking Coefficients    
306
                          Thermal Loading of Cryopumps    
307
                          Sputtering Applications    
309
                          Cryopump Applications    
312
                          System Configurations    
313
                          Regeneration of Cryopumps    
315
                          Standard & Quick Regeneration Methods    
316
                          Reverse Cycle Regeneration    
318
                          The Placebo Effect    
319
                          Sources & Remedies of He Gas Contamination    
320
         5.5 Closed-Loop, Gaseous Helium Refrigerators    
321
                          Some History    
321
                          The GM-Cycle Refrigerator    
323
                          The Expander    
323
                          The Compressor    
326
                          Refrigerator Capacity    
329
                          Networking Cryopumps on Complex Systems    
329
               5.5.4 Meissner Coils & Traps Using Vapor Refrigerants    
331
                Problem Set    
331
                References    
334
SUBJECT INDEX    
345
AUTHOR INDEX    
353
     
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