Atoms in Plasmas

Atoms in Plasmas is concerned with radiative-collisional phenomena in neutral and ionized gases. Central to the studies is a "perturbed atom" that is an atom under the influence of different perturbations in plasmas, namely by electrical and magnetic fields, fields of plasma oscillations, laser and Planck-radiation fields, collisions with excited particles, stochastic accelerations, etc. The treatment covers fundamental aspects of modern physics, such as atomic quantum mechanics and quantum optics, radiation and collisional processes in plasmas and gases, nonlinear laser spectroscopy, plasma diagnostics, etc.

1. Introduction. General Problems of Description of Atomic Spectra in Plasmas.- 1.1 Atomic Physics and Plasma Physics. Quasiclassical Methods for Atomic Processes.- 1.2 General Problems of Atomic-State Mixing in a Plasma Medium. Density Matrix Method.- 2. Classical Motion in an Atomic Potential. Atomic Structure.- 2.1 Classical Radiation Spectra in a Coulomb Field. Peculiarities of the High-Frequency Domain. Kramers’ Electrodynamics.- 2.2 Symmetry Properties of the Coulomb Field.- 2.3 Nonhydrogenic Atoms. Allowed and Forbidden Transitions. Properties of Multicharged Ion Spectra.- 2.3.1 Nonhydrogenic Atomic Spectra Structure. Allowed and Forbidden Transitions.- 2.3.2 Properties of Multicharged Ions (MCI) Spectra.- 2.4 Auto-ionization States. Stationary (Fano) and Time-Dependent (Kompaneets) Descriptions.- 2.4.1 Auto-ionization States.- 2.4.2 The Interaction of Discrete States with a Continuum. Fano and Kompaneets Descriptions.- 2.5 Rydberg Atomic States in Plasmas.- 3. Radiation Itansition Probabilities and Radiation Kinetics in Kramers’ Electrodynamics.- 3.1 Quasiclassical Transition Probabilities.- 3.2 Line Radiation (LR) Probabilities.- 3.3 Photorecombination (PR) Cross Section.- 3.4 Kramers’ Electrodynamics and Radiative Cascades Between Rydberg Atomic States.- 3.4.1 Classical Kinetic Equation.- 3.4.2 Quantum Kinetic Equation in the Quasiclassical Approximation.- 3.4.3 Relationship of the Quasiclassical Solution to the Quantum Cascade Matrix. The Solution in the General Quantum Case.- 3.4.4 Atomic-Level Populations for a Photorecombinative Source. Quasiclassical Scaling Laws.- 4. Fermi Method of Equivalent Photons and the Probabilities of Radiative-Collisional Transitions in Atoms.- 4.1 Applicability of the Fermi Method.- 4.2 Excitation by Electron Impact asAbsorption of Equivalent Photons by an Ion.- 4.3 Dielectronic Recombination as the Resonance Fluorescence of Equivalent Photons.- 4.4 Polarization Radiation as Non-Resonant Scattering of Equivalent Photons.- 5. Hydrogenic Atom in an Electric Field. Quasiclassical Consideration.- 5.1 Quasiclassical Results for the Transition Probabilities and Lifetimes in Parabolic Coordinates.- 5.1.1 Introductory Comments.- 5.1.2 General Relationships.- 5.1.3 Radiative Lifetimes of States.- 5.2 Intensities of the Stark Components.- 5.3 Weak Fields. Asymptotic Theory of the Decay of an Atom.- 5.4 Classical Theory of the Decay of an Atom in an Electric Field.- 5.5 Decay of States Near the Critical Value of an Electric Field.- 5.6 General Theory of Atomic States in an Electric Field.- 5.6.1 Basis of the Semiclassical Approach.- 5.6.2 Energy Levels.- 5.6.3 Decay Rates.- 5.7 Results of Numerical Calculations.- 6. Atom in a Magnetic Field and Crossed F—B Fields.- 6.1 Introductory Remarks. Energy Spectrum of Low Lying Atomic States.- 6.1.1 Energy Spectrum of Lower States.- 6.2 Adiabatic Theory for Highly Excited Atomic States in a Strong Magnetic Field.- 6.3 “Latent” Symmetry of an Atom in a Magnetic Field.- 6.4 Oscillator Strengths of Atomic Transitions in Strong Magnetic Fields.- 6.5 Classical Trajectories of an Atomic Electron in a Magnetic Field. Stochastization Effects.- 6.5.1 Calculation of Classical Trajectories.- 6.5.2 Stochastization of Electron Motion in Coulomb and Magnetic Fields.- 6.5.3 Numerical Calculations of Spectra of an Atom in a Magnetic Field.- 6.6 Hydrogen Atom in Crossed Electric and Magnetic Fields.- 6.6.1 First-Order Theory.- 6.6.2 Second-Order Corrections.- 6.6.3 Atom in Electric and Strong Magnetic Fields.- 6.7 Conclusions.- 7. Atom in a NonresonantOscillating Electric Field.- 7.1 The Types of Oscillating Fields in Plasmas. Quasi-energetic Level Structure.- 7.2 The Blokhintsev Spectrum.- 7.3 Hydrogen Atom in a Rotating Electric Field.- 7.4 Multiphoton Transitions in a Two-Level System.- 7.5 The Quasi-energy Spectrum of a Two-Level System. Intensities of Satellites.- 7.6 Highly Excited Atom in a Low Frequency, Nonresonant Electric Field. Quasiclassical Solution.- 8. Atom in a Resonant Oscillating Electric Field. Simultaneous Influence of Constant and Oscillating Fields.- 8.1 Features of Resonance Conditions in Plasmas.- 8.2 Action of Weak Oscillating Electric Fields of Broad Spectral Composition on the Atom.- 8.3 Hydrogen Atom in Static (S) and Strong Oscillating (Dynamie-D) Fields. Numerical Solutions for the Case when S?D.- 8.4 Analytical Theory of Multiquantum Resonances in S — D Fields.- 8.5 Hydrogen Spectral, Line Structure Near Resonances in S — D Fields.- 8.6 On the Stochastization of Highly Excited Electron Motion in a Periodic Field.- 9. Decay of Atomic States.- 9.1 Resonance of Discrete States Against the Background of a Continuous Spectrum.- 9.1.1 A Number of Discrete States Against the Background of One Continuum.- 9.1.2 Several Continua. Scattering Problems.- 9.1.3 Two-Level Problem with a Stationary Perturbation.- 9.1.4 Certain Examples.- 9.2 Damping of Atomic States Due to Their Relaxation in Plasmas.- 9.2.1 Impact Relaxation of Atomic Levels.- 9.2.2 Features of the Spectral Line Shape Under Impact Relaxation of Atomic Sublevels in an Ion Field.- 9.3 Emission of Forbidden Spectral Lines and the Decay of Metastable Levels in Plasmas.- 9.3.1 The Polarization Mechanism for Forbidden Transitions in an Atom.- 9.3.2 Interrelation Between the Nonelastic and Polarization Mechanisms. The WeisskopfMechanism for Inelastic Transitions.- 9.3.3 The Adiabatic Approximation for Polarization Radiation.- 9.4 Decay of Atomic States and Some Elementary Processes in Plasmas.- 9.4.1 Transition Discrete Spectrum — Continuum in Hydrogenic Plasmas.- 9.4.2 Charge Exchange of Atoms at Multicharged Ions as a Decay Process.- 9.4.3 Auto-ionization Decays and Dielectronic Recombination in Plasmas.- 10. Excited Hydrogen-Like Atom in Electrical Fields of Charged Particles.- 10.1 The Atomic State Evolution in the Electric Field of a Classically Moving Charged Particle.- 10.2 Effect of the Hydrogenic State Mixing During Charge Exchange of an Atom at the Multicharged Ion.- 10.3 Quantum Motion of an Electron in an Electric Field of Hydrogen-Like Atom or Ion. Connection with the Line-Broadening Problem.- 10.3.1 Classical and Quantum Formulations of the Problem of Electron Interaction with an Excited Atom.- 10.3.2 The System of Wave Functions of an Excited Hydrogen Atom and a Broadening Particle.- 10.3.3 The Hydrogen Line Shape and the Overlap Integral of the Wave Functions of a Broadening Particle.- 10.3.4 Generalization onto the Case of Hydrogen-Like Ions.- 10.4 Differential Cross Sections for Electron and Ion Scattering at the Excited Hydrogen Atom. Precise Solutions.- 11. Collisions of an Atom with Atomic Particles in External Fields.- 11.1 Collisional Transitions Between Fine Structure Sublevels of a Hydrogen Atom in a Magnetic Field.- 11.2 Collisions of a Two-Level Atom with Particles in a Strong Resonant Electromagnetic Field.- 11.2.1 Optical Collisions. The Basic System of Equations.- 11.2.2 Optical Collisions and Characteristics of Light Absorption in Media.- 11.3 Landau-Zener Mechanism of Strong Electromagnetic (E.M.) Radiation Absorption in the Wings of a Spectral Line.- 11.3.1Landau-Zener Model for Optical Phenomena.- 11.3.2 Nonlinear Effects in Absorption for the Collision of Identical Atoms.- 11.3.3 Experimental Aspects.- 11.4 Multiparticle Effects. The Change of the Atom’s Quantization Direction in a Laser Field.- 11.4.1 Multiparticle Approach to the Powerful Radiation Absorption by the Atom in a Plasma.- 11.4.2 Calculation of Spectra in a Laser Field.- 11.4.3 The Change of the Atom Quantization Direction in a Laser Field.- 11.5 Radiative Collisions.- 11.6 Effect of the Electric Microfield on Resonant Charge Exchange in a Dense Medium.- 12. The Influence of Regular and Stochastic Accelerations on Atomic Spectra.- 12.1 Regular Acceleration. Adiabatic Population Inversion in a Strong Laser Field.- 12.1.1 Landau-Zener Nonlinearities in the Spectra of a Two-Level System Subjected to Acceleration.- 12.1.