Physics of Highly Charged Ions

The physics of highly charged ions has become an essential ingredient of many modern research fields, such as x-ray astronomy and astrophysics, con­ trolled thermonuclear fusion, heavy ion nuclear physics, charged particle ac­ celerator physics, beam-foil spectroscopy, creation of xuv and x-ray lasers, etc. A broad spectrum of phenomena in high-temperature laboratory and astrophysical plasmas, as well as many aspects of their global physical state and behaviour, are directly influenced, and often fully determined, by the structure and collision properties of multiply charged ions. The growth of in­ terest in the physics of highly charged ions, experienced especially in the last ten to fifteen years, has stimulated a dramatic increase in research activity in this field and resulted in numerous significant achievements of both fun­ damental and practical importance. This book is devoted to the basic aspects of the physics of highly charged ions. Its principal aim is to provide a basis for understanding the structure and spectra of these ions, as well as their interactions with other atomic par­ ticles (electrons, ions, atoms and molecules). Particular attention is paid to the presentation of theoretical methods for the description of different radi­ ative and collision phenomena involving multiply charged ions. The exper­ imental material is included only to illustrate the validity of theoretical methods or to demonstrate those physical phenomena for which adequate theoretical descriptions are still absent. The general principles of atomic spectroscopy are included to the extent to which they are pertinent to the subject matter.

1. Introduction.- 1.1 General Overview.- 1.2 Basic Features of Highly Charged Ions and Their Interactions.- 1.3 Highly Charged Ions in Astrophysics.- 1.4 Highly Charged Ions in Controlled Thermonuclear Fusion Research.- 1.5 Highly Charged Ions in Accelerator-Based Physics and Other Research Fields.- 1.6 Scope of the Book.- 2. Structure and Spectra of Highly Charged Ions.- 2.1 General Properties of the Spectra.- 2.2 Satellites of the Spectral Lines.- 2.3 Classification of the States and Spectral Lines of Multiply Charged Ions.- 2.4 Relativistic and Radiative Effects.- 2.5 Decay of Excited Ionic States. Radiation and Autoionization.- 2.6 Static and Dynamic Dipole Polarizabilities of Multiply Charged Ions.- 2.6.1 General Remarks.- 2.6.2 Static Polarizability.- 2.6.3 Dynamic Polarizability.- 3. Radiative Processes in the Continuous Spectrum.- 3.1 Bremsstrahlung.- 3.2 Photoionization and Photorecombination.- 3.3 Dielectronic Recombination.- 3.3.1 Resonance Character of the Process.- 3.3.2 Theory and Experiment.- 3.4 Autoionization.- 4. Electron Collisions with Highly Charged Ions: General Theory and Excitation Processes.- 4.1 Introductory Remarks.- 4.2 Basic Equations.- 4.3 Effective-Range Theory for Attractive Coulomb Field.- 4.4 Quantum Defect Method. The Seaton Theory.- 4.5 Correct Asymptotic Expansion. Influence of Dielectronic Recombination.- 4.5.1 Radial Green’s Function.- 4.5.2 Solution of Integral Equations.- 4.5.3 T Matrix and Cross Sections.- 4.5.4 Radiative Decay of Resonances.- 4.6 Results of Calculations and Experimental Data.- 5. Electron-Impact Ionization of Highly Charged Ions.- 5.1 One-Electron Ionization. General Remarks.- 5.2 Exchange Effects in Ionization. The Peterkop Theory.- 5.3 Threshold Behaviour of the Cross Section.- 5.4 Quantum-Mechanical Methods for Ionization Cross Section Calculations.- 5.5 Classical and Semi-Empirical Formulae.- 5.6 Excitation-Autoionization.- 5.7 Experimental Data and Comparison with Theoretical Calculations.- 5.8 Analytic Approximations for the Quantum-Mechanical Cross Sections.- 6. Collisions of Atoms with Highly Charged Ions: General Theoretical Description.- 6.1 Two-Coulomb-Centre Problem.- 6.1.1 The Eigenvalue Problem.- 6.1.2 Correlation Rules and Pseudocrossings.- 6.1.3 Energy Splitting at a Pseudocrossing.- 6.1.4 Algorithms for Solving the Eigenvalue Problem for the (Z1, e, Z2) System.- 6.1.5 Application of the Two-Centre Problem to Many-Electron Diatomic Molecules: Molecular Orbital Model.- 6.2 Close-Coupling Methods.- 6.2.1 General Formulation of the Close-Coupling Methods.- 6.2.2 Molecular-Orbital Close-Coupling (MO ― CC) Methods.- 6.2.3 Atomic-Orbital Close-Coupling (AO ― CC) and Related Methods.- 6.2.4 Two-State Close-Coupling Models and Approximations.- 6.3 Perturbation Methods.- 6.3.1 Formal Theory of Atomic Reactions.- 6.3.2 Born Series.- 6.3.3 Distorted-Wave Method.- 6.3.4 Perturbation Treatment of Close-Coupled Equations.- 6.3.5 Second-Order and Related Approximations.- 6.4 Classical Descriptions.- 6.4.1 Binary-Encounter Approximation (BEA).- 6.4.2 Classical Trajectory Monte Carlo (CTMC) Method.- 7. Collisions of Atoms (Ions, Molecules) with Highly Charged Ions: Charge-Transfer Processes.- 7.1 General Considerations.- 7.2 Charge Exchange at Low Energies.- 7.2.1 Decay Models.- 7.2.2 Multichannel Landau-Zener Model.- 7.2.3 Molecular-Orbital Close-Coupling Calculations.- 7.2.4 Analytic Treatment of Diabatic MO ― CC Equations.- 7.3 Electron Capture at Intermediate Energies.- 7.3.1 AO―CC Method: Numerical Calculations.- 7.3.2 Approximate Treatments of Coupled-Channel Equations.- 7.3.3 Classical Treatments.- 7.4 Electron Capture at High Energies.- 7.4.1 The Brinkman-Kramers Approximation and Its Extensions.- 7.4.2 Higher-Order Approximations.- 7.4.3 Electron Capture into Continuum States.- 7.5 General Features of Single-Charge-Transfer Cross Sections.- 7.5.1 Scaling Laws for the Total Single-Charge-Transfer Cross Section.- 7.5.2 Final-State Distributions of Captured Electrons.- 7.5.3 Z-Oscillations of the Total Cross Sections.- 7.6 Single-Charge Transfer in Ion-Ion and Ion-Molecule Collisions.- 7.6.1 Ion-Ion Charge Exchange.- 7.6.2 Ion-Molecule Charge Exchange.- 7.7 Multiple-Charge Transfer.- 7.7.1 Two-Electron-Capture Processes.- 7.7.2 Multi-Electron-Capture Processes.- 8. Collisions of Atoms (Ions) with Highly Charged Ions: Excitation and Ionization.- 8.1 Basic Electron Transition Mechanisms.- 8.2 Excitation Processes.- 8.2.1 Close-Coupling Treatments.- 8.2.2 UDWA Treatment.- 8.2.3 Perturbation Theory and VPS Approximation.- 8.2.4 Excitation in Ion-Ion Collisions.- 8.3 Single-Electron Ionization.- 8.3.1 Perturbation Treatments.- 8.3.2 DACC Theory for Ionization.- 8.3.3 UDWA Calculations.- 8.3.4 Classical Models.- 8.3.5 Higher-Order High-Energy Approximations.- 8.3.6 Ion-Ion and Ion-Molecule Ionization.- 8.3.7 Scaling Laws for Single-Electron Ionization.- 8.3.8 Direct Multiple-Ionization.- 8.4 Electron Loss and Stripping Processes.- 8.4.1 The Keldysh Quasi-Classical Method.- 8.4.2 Classical Treatments.- 8.4.3 Stripping Reactions.- 9. Auger, Inner-Shell and Related Processes.- 9.1 Collisional Auger Processes Involving Outer Shells.- 9.1.1 Capture-Excitation.- 9.1.2 Capture-Ionization.- 9.1.3 Multiple Transfer Ionization.- 9.2 Inner-Shell Processes.- 9.2.1 Basic Electron Transition Mechanisms.- 9.2.2 K- and L-Shell Excitations.- 9.2.3 Vacancy Sharing.- 9.2.4 Correlated Electron Transitions in Vacancy Production and Decay.- 9.3 Some Aspects of Quasi-Molecule and Quasi-Atom Formation in Heavy Ion Collisions.- 9.3.1 Quasi-Molecular X-Ray Radiation.- 9.3.2 Positron Emission.- 10. Rate Coefficients of Elementary Processes.- 10.1 Energy (Velocity) Distribution Function.- 10.2 Electron-Impact Excitation.- 10.3 Electron-Impact Ionization.- 10.4 Photorecombination.- 10.5 Dielectronic Recombination.- 10.6 Charge Transfer.- References.