Chemistry Reference
In-Depth Information
3
Physics of Nonthermal
Plasmas
CONTENTS
3.1 Basic Concepts of Plasma Physics.............................................17
3.1.1 Introduction and Basic Items..........................................17
3.1.1.1 Classification of Plasmas Concerning Their Energy
Content ......................................................17
3.1.1.2 IonizationDegree...........................................19
3.1.1.3 Quasi-Neutrality and Debye Shielding ....................19
3.1.2 Debye Shielding Length...............................................20
3.1.3 Plasma Frequency......................................................22
3.1.4 High-Frequency Conductivity and Permittivity of Plasmas .........24
3.1.5 AmbipolarDiffusionof ChargedParticles ...........................27
3.1.6 Motion of Charged Single Particle in Homogeneous
Magnetic Field .........................................................29
3.1.6.1 CyclotronMotion...........................................29
3.1.6.2 Drift Velocity Perpendicular to the Magnetic Field
due to Additional External Forces .........................31
3.1.6.3 Influence of Collisions on Charged Particle Transport
in Magnetized Plasmas .....................................33
3.2 ThermalandNonthermalPlasmas.............................................33
3.2.1
Plasma in Thermodynamic Equilibrium ..............................33
3.2.1.1
Complete Thermodynamic Equilibrium ...................33
3.2.1.2
Local Thermodynamic Equilibrium........................35
3.2.2
Nonequilibrium Plasmas ..............................................36
3.3
Elementary Collision Processes and Cross Sections ..........................38
3.3.1 Introduction and Overview ............................................38
3.3.1.1 Dynamics of Elastic and Inelastic Collisions..............39
3.3.2 Collision Processes in Nonthermal Plasmas and Their
Classification...........................................................42
3.3.3 Collision Cross Section................................................48
3.3.3.1 GasKineticCrossSection..................................48
3.3.3.2 PolarizationCrossSection..................................49
3.3.3.3 CoulombScattering.........................................53
3.3.3.4
Electron Attachment Cross Section ........................55
3.3.3.5
Electron Impact Excitation and Ionization
CrossSection................................................55
3.3.3.6
Cross Section of the Neutral-Neutral Reaction at
ThermalVelocitywithThresholdEnergy .................59
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