Fundamental Aspects of Plasma Chemical Physics (eBook)

Mario Capitelli, University of Bari, mario.capitelli@ba.imip.cnr.itGianpiero Colonna, IMIP CNRFabrizio Esposito, IMIP CNRKhaled Hassouni, Institut Galilee-Univeriste ParisAnnarita Laricchiuta, IMIP CNRSavino Longo, University of Bari

Preface 8
Acknowledgments 10
Contents 12
Introduction 16
1 Electron-Molecule Collision Cross Sections and Rate Coefficients 18
1.1 Theoretical Model of Resonant Collisions 19
1.2 Resonant Collisions Involving Atmospheric Molecules 24
1.2.1 N2, O2 and NO Molecules 24
1.2.2 CO and CO2 Molecules 30
1.3 Electron-Molecule Collisions in Fusion Plasmas 34
1.3.1 CH, BeH+, and BeH Molecules 35
1.3.2 Resonant Processes Involving H2 Molecule 41
References 44
2 Reactivity and Relaxation of Ro-Vibrationally Excited Molecules 48
2.1 Computational Method 48
2.2 H+H2 51
2.2.1 Isotopes and Scaling Relations 54
2.3 N+N2 54
2.4 O+O2 68
2.5 Future Developments 69
References 70
3 Atom Recombination at Surfaces 74
3.1 Hydrogen on Graphite Surface 77
3.2 Hydrogen on Metals 82
3.3 Oxygen and Nitrogen on Silica 86
3.4 vdfs in Catalysis: A Phenomenological Approach 88
References 93
4 Kinetic and Monte Carlo Approaches to Solve Boltzmann Equation for eedf 96
4.1 Boltzmann Equation in Two-Term Approximation 97
4.1.1 Theoretical Model 97
4.1.1.1 Two-Term Approximation 98
4.1.1.2 Differential Equations 101
4.1.1.3 Quasi-stationary Approximation 104
4.1.1.4 Electrons in Flow 105
4.1.1.5 Electron Energy Distribution 107
4.1.1.6 Electron Kinetics in Nozzle Flow 110
4.1.1.7 Transport Properties 112
4.1.1.8 When Quasi-steady Approximation Fails 114
4.1.2 Numerical Aspects in the Solution of BE 115
4.1.3 Negative Electron Conductivity 117
4.2 Monte Carlo Method for Electron Transport 117
References 126
5 Superelastic Collisions and Electron Energy Distribution Function 129
5.1 Boltzmann Equation for Atomic and Molecular Plasmas 130
5.1.1 Inelastic Collisions 131
5.1.2 Superelastic Collisions 131
5.1.3 A Golden Rule for Superelastic Collisions 132
5.2 Atomic and Molecular Plasmas 134
5.2.1 Case 1: Pure CO 134
5.2.2 Case 2: Pure He 135
5.2.3 Case 3: He-CO Mixture 136
5.3 Time Evolution of eedf 138
5.3.1 Post-discharge Conditions 138
5.3.1.1 Penning Ionization and Superelastic Electronic Collisions 138
5.3.1.2 Post-discharge and Electron-Electron Collisions 139
5.3.2 eedf Evolution During Discharges 143
5.3.3 Abrupt Change of E/N 143
5.3.4 RF Bulk Discharges 147
5.3.4.1 Nitrogen Plasma 147
5.3.4.2 Excimer Laser Mixture 150
5.3.5 Case Study: Excimer Laser Kinetics 151
5.3.6 Photoresonant Plasmas 153
5.4 Experimental Determination of eedf 154
References 156
6 Collisional-Radiative Models for Atomic H Plasmas 159
6.1 Equilibrium Relations 160
6.1.1 Boltzmann Relation 160
6.1.2 Saha Relation 161
6.1.3 Maxwell Distribution 161
6.1.4 Planck Spectral Distribution 162
6.2 Non-equilibrium Atomic Plasma 162
6.2.1 Electron Impact Excitation 163
6.2.1.1 Electron Impact Ionization/Recombination 164
6.2.2 Radiative Transitions 164
6.2.2.1 Radiative Recombination 165
6.2.3 Master Equations for Spatially Homogenous Plasma 166
6.3 Cross Sections and Rate Coefficients 167
6.3.1 Excitation by Electron Impact 167
6.3.2 Electron Impact Ionization 169
6.3.3 Spontaneous Emission 171
6.4 Radiative Recombination 172
6.5 QSS Approximation 173
6.5.1 QSS Approximation (General Equations) 173
6.5.2 Interpretation of Xi0 e Ri1 176
6.6 QSS Results for Optically-Thin Atomic H Plasmas 177
6.7 Time-Dependent Results 178
6.7.1 Ionizing Plasma ?< 0
6.7.2 Large Deviations from Equilibrium 182
References 187
7 Vibrational Kinetics 190
7.1 Vibrational Kinetics of Diatomic Molecules 191
7.1.1 VT Terms 191
7.1.2 VV Terms 193
7.1.2.1 Some Considerations About VV Processes 194
7.1.3 Dissociation-Recombination Terms 196
7.1.3.1 Ladder Climbing Model 198
7.2 Vibrational Relaxation Kinetics 198
7.2.1 Sudden Decrease of Gas Temperature 199
7.2.2 Laser Pumping of CO 201
7.2.3 Pumping of CO by Vibrationally Excited N2 202
7.2.4 Boundary Layer 206
7.3 Vibrational Kinetics Under Plasma Conditions 210
7.3.1 Laser-Plasma Interaction 213
Appendix 1: Non-equilibrium Vibrational Distributions: General Considerations 214
Appendix 2 216
References 217
8 Particle Models for Low Pressure Plasmas 220
8.1 Time Scales 221
8.2 Particle Models 222
8.3 Dynamic Particle List 223
8.4 Self-Consistent Approach 224
8.5 Worked Example: RF Model for Hydrogen 226
8.5.1 The Model 227
8.5.2 Solutions to Reduce the Computational Effort 229
8.5.3 Test Case 230
8.5.4 Some Results for Hydrogen 230
8.5.5 Ion Energy Distribution Functions (iedf) in H2 RF Discharge 232
References 236
9 Self-Consistent Kinetics of Molecular Plasmas: The Nitrogen Case 238
9.1 Database of N2 Processes 239
9.2 Excited State Kinetics and eedf Under Discharge Conditions 242
9.3 Excited State Kinetics and eedf Under Post-discharge (Afterglow) Conditions 251
9.3.1 Short Time Pulsed Discharges 252
9.3.2 Nitrogen Afterglow Following Continuous Discharges 253
References 256
10 Negative Ion H- for Fusion 261
10.1 The Kinetic Model 262
10.2 Time-Dependent Pulsed Discharges 271
10.3 Rydberg States 274
10.4 RF Coupled Negative Ion Sources 276
10.5 Negative Ion Energy Distribution Function 280
References 283
11 Non Equilibrium Plasma in High Enthalpy Flows 288
11.1 Fluid Dynamic Model for State-to-State Kinetics 289
11.2 N2 Vibrational Kinetics in Nozzle 291
11.3 Air Vibrational Kinetics in Nozzle 295
11.4 Ionizing Nitrogen Mixture 298
11.5 Nozzle Expansion in the Presence of Electric and Magnetic Field 301
11.6 The Role of Radiation in High Enthalpy Flows 306
11.6.1 Shock Tube 306
11.6.2 Nozzle Flow 311
References 314
12 Toward the Activation of Polyatomic Molecules by eV Processes: The CO2 Case Study 317
References 323
Index 325