The progress in the physics of highly-ionized atoms since the last NATO sponsored ASI on this subject in 1982 has been enormous. New accelerator facilities capable of extending the range of highly-ionized ions to very high-Z have come on line or are about to be completed. We note particularly the GANIL accelerator in Caen, France, the Michigan State Superconducting Cyclotrons in East Lansing both of which are currently operating and the SIS Accelerator in Darmstadt, FRG which is scheduled to accelerate beam in late 1989. Progress i~ low-energy ion production has been equally dramatic. The Lawrence Livermore Lab EBIT device has produced neon-like gold and there has been continued improvement in ECR and EBIS sources. The scientific developments in this field have kept pace with the technical developments. New theoretical methods for evaluating relativistic and QED effects have made possible highly-precise calcula tions of energy levels in one-and two-electron ions at high-Z. The calculations are based on the MCDF method and the variational method and will be subject to rigorous experimental tests. On the experimental side, precision x-ray and UV measurements have probed the Lamb shift in the one and two electron ions up to Z=36 with increasing precision.

The last decade has seen dramatic progress in the development of devices for producing mu1ticharged ions. Indeed it is now pos sible to produce any charge state of any ion right up through 92 fully-stripped uranium (U +). Equally dramatic progress has been achieved in the energy range of the available ions. As an example, fully-stripped neon ions have been produced in useable quantities with kinetic energies ranging from a few ev to more than 20 Gev. Interest in the atomic physics of multicharged ions has grown apace. In the fusion program, the spectra of these ions is an im portant diagnostic tool. Moreover the presence of mu1ticharged ions presents a serious energy loss mechanism in fusion devices. This fact has motivated a program to study the collision mech anisms involved. In another area, mu1ticharged ions are present in the solar corona and the interstellar medium and knowledge of their collision properties and spectra is essential to understand ing the astrophysics. Other possible applications are to x-ray lasers and heavy ion inertial fusion. On a more fundamental level, new possibilities for testing quantum electrodynamics with mu1ti charged ions have emerged.

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.

An introduction to the physics of highly excited, easily perturbed or interacting atoms. Covers Rydberg states, quantum defect theory, atomic f-values, centrifugal barrier effects, autoionisation, inner shell and double excitation spectra, K-matrix theory, atoms in high laser fields, statistical methods, quantum chaos, and atomic effects in solids.

In this thesis, the ionization of atoms and small molecules in strong laser fields is experimentally studied using a reaction microscope. The population of autoionizing doubly excited states in the laser fields is proven and a possible connection to the well-known dielectronic recombination processes is discussed. The fundamental process of tunnel ionization in strong laser fields is subject of investigation in a pump-probe experiment with ultrashort laser pulses. A coherent superposition of electronic states in singly charged argon ions is created within the first, and subsequently tunnel-ionized with the second pulse. This gives access to state-selective information about the tunneling process and allows to test common models. Moreover, the ionization of krypton and argon at different wavelengths is studied, from the multiphoton to the tunneling regime. The wavelength-dependent investigations are furthermore extended to molecular hydrogen. In addition to ionization, this system might undergo different dissociative processes. Channel-selective electron momentum distributions are presented and compared to each other.

Recent years have seen a growing interest in the effects of relativity in atoms, molecules and solids. On the one hand, this can be seen as result of the growing awareness of the importance of relativity in describing the properties of heavy atoms and systems containing them. This has been fueled by the inadequacy of physical models which either neglect relativity or which treat it as a small perturbation. On the other hand, it is dependent upon the technological developments which have resulted in computers powerful enough to make calculations on heavy atoms and on systems containing heavy atoms meaningful. Vector processing and, more recently, parallel processing techniques are playing an increasingly vital role in rendering the algorithms which arise in relativistic studies tractable. This has been exemplified in atomic structure theory, where the dominant role of the central nuclear charge simplifies the problem enough to permit some prediction to be made with high precision, especially for the highly ionized atoms of importance in plasma physics and in laser confinement studies. Today's sophisticated physical models of the atom derived from quantum electrodynamics would be intractable without recourse to modern computational machinery. Relativistic atomic structure calculations have a history dating from the early attempts of Swirles in the mid 1930's but continue to provide one of the primary test beds of modern theoretical physics.

It is perhaps surprising that a process which was one of the first to be studied on an atomic scale, and a process which first received attention over seven decades ago, continues to be the object of diverse and intense research efforts. Such is the case with the (seemingly) conceptually simple and familiar mechanism of electron impact ionization of atoms, molecules, and ions. Not only has the multi-body nature of the collision given ground to theoretical effort only grudgingly, but also the variety and subtlety of processes contributing to ionization have helped insure that progress has come only with commensurate work: no pain - no gain. Modern experimental methods have made it possible to effectively measure and explore threshold laws, differential cross sections, partial cross sections, inner-shell ionization, and the ionization of unstable species such as radicals and ions. In most instances the availability of experimental data has provided impetus and guidance for further theoretical progress.