Foreword ....................................................... xv
Preface ....................................................... xix
Acknowledgments ............................................. xxiii
Author ........................................................ xxv
1 Introduction ................................................. 1
Plasma ....................................................... 1
What Is Plasma? ........................................... 1
Plasma as a Fourth State of Matter ........................ 1
Physics of Plasma Production .............................. 2
Ways of Creating Plasmas in the Laboratory ................ 2
Particle Interactions ........................................ 3
Some Basic Plasma Properties ................................. 3
Criterion for the Definition of a Plasma ..................... 5
Different Types of Plasmas ................................... 7
Description of Plasmas ...................................... 10
Theoretical Approaches ...................................... 12
Microwave-Generated Plasmas ................................. 12
Compact Microwave Plasma Sources ............................ 13
Research Objective and Methods .............................. 14
Note ........................................................ 15
References .................................................. 16
2 Review of the Cutoff Problem ................................ 19
A Brief History of Earlier Work ............................. 19
Microwave Propagation in Waveguides ......................... 20
Waveguide Geometrical Cutoff ............................. 21
Rectangular Waveguide ................................. 21
Circular Waveguide .................................... 23
Waveguide Filled with a Plasma ........................... 25
Effect of a Magnetic Field ............................ 27
Plasma Density Cutoff ....................................... 28
Ordinary Wave ............................................ 28
Extraordinary Wave ....................................... 28
References .................................................. 29
3 Plasma and Wave Diagnostics ................................. 33
Plasma Diagnostics with Langmuir's Probes ................... 33
Single Langmuir Probe .................................... 33
Electron Saturation Region ............................ 36
Ion Saturation Region ................................. 37
Methods to Determine Plasma Parameters ................... 37
Electron Temperature (Te) ............................. 37
Electron Density (Ne) ................................. 37
Ion Density (N+) ...................................... 38
Space Potential (Vs) and Floating Potential (Vƒ) ...... 38
Practical Difficulties Encountered in Determination
of the Plasma Parameters ................................. 39
Measurement of the Electron Energy Distribution .......... 40
Retarding Field Analyzer Probe (or Electron Energy
Analyzer) ................................................ 42
Ion Energy Analyzer Probe ................................ 43
Design of Electromagnetic Probes ............................ 45
Wave Electric Field Probe ................................ 47
B-Dot Probe .............................................. 47
References .................................................. 48
4 Genesis of a Wave Induced Discharge: A New Perspective ...... 51
Introduction ................................................ 51
Historical Development of Breakdown Studies ................. 52
Modeling of the Electron Dynamics ........................... 53
Development of the General Algorithm ........................ 56
Field-Free Case: Three-Dimensional Random Walk .............. 60
Electron Transport in the Presence of an EM Field ........... 61
Magnetostatically Assisted Electron Transport in the
Presence of an EM Field ..................................... 65
Electric Field Effects and the Random Walk Parameter ........ 69
Linear and Circularly Polarized Waves ....................... 71
Summary and Conclusion ...................................... 72
References .................................................. 73
5 Plasma Production in Continuous-Mode Microwaves:
Near-Circular Multicusp ..................................... 75
Introduction ................................................ 75
Apparatus ................................................... 75
Vacuum Chamber ........................................... 76
Microwave System ......................................... 77
Vacuum Pumps ............................................. 78
Pressure Gauges .......................................... 79
Multicusp Design ............................................ 79
Waveguide Design ............................................ 80
Experimental Results ........................................ 81
Spatial Profiles of the Plasma .............................. 84
Discussion .................................................. 86
On the Possible Reasons for Plasma Production ............ 86
On the Produced Plasma ................................... 87
Conclusions ................................................. 89
References .................................................. 89
6 Plasma Production in Continuous-Mode Microwaves:
Rectangular Nonmulticusp Waveguide .......................... 91
Introduction ................................................ 91
Experimental Procedures ..................................... 92
Waveguide Design ......................................... 92
Magnetic Field Design .................................... 94
Measurement of the Reflected Power and the Ion Current ... 95
Experimental Results ........................................ 95
O-like" Mode Propagation (Ј || B) ........................ 95
"X-Like" Mode Propagation (Ј | B) ........................ 98
Discussion .................................................. 99
"O-Like" Mode Propagation (Ј || B) ...................... 100
"X-Like" Mode Propagation Case (Ј | B) .................. 101
Conclusions ................................................ 102
References ................................................. 103
7 Comparison of Square and Near-Circular Multicusp
Waveguides ................................................. 105
Introduction ............................................... 105
Waveguide Design ........................................... 106
Experimental Results ....................................... 107
Discussion ................................................. 109
Comparison of the Effect of Cross-Section ............... 109
Mechanisms of Plasma Maintenance ........................ 113
Ionization Effects of the Space Potential and the
Electron Temperature ................................. 113
Reduction of the Wavelength λ due to UHR ............. 114
Existence of Pass Band for Wave Propagation .......... 115
Conclusions ................................................ 119
Summary of Experimental Results in Continuous-Mode
Microwaves ................................................. 119
Summary of the Plasma Production Mechanisms ................ 121
Plasma Ignition at the Waveguide Entrance ............... 121
Potential Ionization and Confinement .................... 121
Confinement by the Minimum-B Magnetic Field ............. 121
Plasma Diffusion into the Waveguide ..................... 123
Waveguide's Reduced Dimension ........................... 123
Wave Propagation with a Reduced Wavelength and
Existence of Pass Bands ................................. 123
References ................................................. 123
8 Plasma Production in Pulsed-Mode Microwaves:
General Experiment ......................................... 125
Introduction ............................................... 125
Apparatus and Methods in the General Experiment ............ 127
Apparatus and Methods of the Experiment with a Circular
Waveguide with a Dimension below Cutoff .................... 129
Some Additional Details of the Experimental Set-Up ......... 130
Microwave Source ........................................ 130
Boxcar Integrator ....................................... 130
Digital Oscilloscopes ................................... 131
Probe for Measuring the Electric Field .................. 132
Experimental Results ....................................... 132
Discussion ................................................. 135
Argon ................................................... 136
Nitrogen ................................................ 137
Standard Air ............................................ 138
Conclusions ................................................ 140
References ................................................. 140
9 Plasma Production in Pulsed-Mode Microwaves: Circular
Multicusp Waveguide with a Dimension below Cutoff .......... 143
Introduction ............................................... 143
Experimental Setup and Procedures .......................... 144
Experimental Results ....................................... 146
Discussion ................................................. 156
On the Mechanisms of Plasma Production .................. 156
Modeling of the Spatiotemporal Current Profiles ......... 156
Discussion ................................................. 161
Electric Field Penetration .............................. 162
Plasma Buildup .......................................... 162
Pulse Repetition Frequency and Pulse Duration ........... 163
Conclusions ................................................ 163
References ................................................. 164
10 Plasma Buildup by Short-Pulse, High-Power Microwaves ....... 165
Introduction ............................................... 165
Experiments ................................................ 166
Discussion ................................................. 171
Electron Temperature Growth during the Pulse ............ 172
Plasma Evolution after the End of Pulse ................. 174
On the Experimental Results ............................. 176
Conclusion ................................................. 178
References ................................................. 178
11 Power Absorption and Intense Collimated Beam Production
in a Pulsed High-Power Microwave Ion Source ................ 181
Introduction ............................................... 181
Ion Source Design and Experimental Setup ................... 182
Experimental Results ....................................... 182
Discussion ................................................. 185
Conclusions ................................................ 186
Summary in Pulsed Microwaves ............................... 187
Experimental Results .................................... 187
General Properties of the Plasma ........................ 187
Plasma Characteristics in the Circular Waveguide ........ 188
Summary of the Plasma Production Mechanisms ............. 188
Continuation of the High Electron Temperature ........ 188
Penetration of the Electric Field .................... 189
Particle Diffusion into the Waveguide ................ 189
Effect of Finite Length of the Waveguide ............. 189
References ................................................. 189
12 New Experiments in Continuous-Mode Microwaves: Formation
of Standing Waves and Electron Trapping .................... 191
Overview of the New Experimental System .................... 191
Introduction ............................................... 194
Spatial Plasma Characteristics ............................. 195
Axial Wave Field Intensity Measurements .................... 196
Electron Trapping in SW Minima ............................. 198
Model Calculation .......................................... 199
Summary and Discussion ..................................... 203
References ................................................. 204
13 Penetration and Screening of Perpendicularly Launched
Electromagnetic Waves ...................................... 207
Introduction ............................................... 207
Experimental Setup ......................................... 208
Experimental Observation ................................... 213
Modeling ................................................... 217
Modeling Results ........................................... 221
Discussion and Summary ..................................... 225
References ................................................. 227
14 Wave Birefringence in Perpendicular Propagation ............ 231
Introduction ............................................... 231
Polar Plasma Characteristics ............................... 233
Polar Wave Field Intensity Measurements .................... 233
Modeling of the Wave Birefringence ......................... 235
Discussion anci Summary .................................... 238
References ................................................. 238
15 Electron Localization and Trapping Physics Revisited ....... 241
Introduction ............................................... 241
Experimental Setup ......................................... 242
Experimental Results ....................................... 243
Modeling ................................................... 248
Modeling Results ........................................... 250
Summary and Discussion ..................................... 252
References ................................................. 254
16 New Experiments in Pulsed Microwaves: Quasisteady-State
Interpulse Plasmas ......................................... 257
Introduction ............................................... 257
Experiment ................................................. 258
Experimental Results ....................................... 260
Model Calculation .......................................... 264
Temporal Evolution of the Electron Energy ............... 264
Temporal Evolution of the Plasma ........................ 265
Discussion and Conclusion .................................. 270
References ................................................. 271
17 Electron Plasma Waves Inside Large-Amplitude
Electromagnetic Pulses ..................................... 273
Introduction ............................................... 273
Experimental Setup ......................................... 274
Experimental Results ....................................... 276
Time-Frequency Analysis .................................... 281
Model ...................................................... 281
Temporal Variation of the Electron Current .............. 281
Spatial Variation of the Electron Current ............... 286
Summary .................................................... 288
References ................................................. 289
18 Transition from Interpulse to Afterglow Plasmas ............ 291
Introduction ............................................... 291
Experimental Setup ......................................... 292
Results .................................................... 294
Summary .................................................... 299
References ................................................. 300
19 Introduction to Focused Ion Beams .......................... 303
Focused Ion Beams .......................................... 303
Microwave Plasma Sources ................................ 304
References ................................................. 304
20 Experimental Setup for Basic Plasma Studies ................ 307
Introduction ............................................... 307
Basic Plasma Experiments ................................... 307
Measurement of Plasma Parameters ........................... 308
Sub-Cutoff Dimensional Plasma Sources ...................... 311
Plasma Generation ....................................... 312
Plasma Sustenance ....................................... 314
Conclusion ................................................. 318
References ................................................. 320
21 Basic Beam Studies: Extraction and Ion Energy
Distribution ............................................... 321
Introduction ............................................... 321
Experiment ................................................. 321
Total Beam Current Measurements ......................... 322
Ion Energy Spread Measurements .......................... 322
Results and Discussion ..................................... 323
Ion Energy Distribution along the Radial Direction ...... 328
Total Beam Current Measurements ......................... 329
Ion Energy Spread Measurements .......................... 332
Conclusion ................................................. 333
References ................................................. 334
22 Multielement Focused Ion Beam .............................. 337
Introduction ............................................... 337
Beam Column of MEFIB ....................................... 337
Beam Simulation Codes ...................................... 338
Results and Discussion ..................................... 338
Single-EL System ........................................ 338
Double-EL System ........................................ 340
Tolerance Studies .......................................... 345
Conclusion ................................................. 346
References ................................................. 347
23 Focused Ion Beam Experiments ............................... 349
Introduction ............................................... 349
Results and Discussion ..................................... 349
Focused Beam Current Measurements ....................... 349
Case A .................................................. 350
Beam Profile Measurements ............................... 352
Beam Spot Size Measurements ............................. 356
Conclusion ................................................. 357
References ................................................. 357
24 Summary and Future Prospects ............................... 359
Index ......................................................... 363
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