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These proceedings present a selection of invited and contributed papers presented during the 18th International Conference on X-Ray Lasers (the 18th ICXRL), held in Shanghai, China, from 17 to 21 July 2023. The conference is part of an ongoing series dedicated to recent developments in the science and technology of X-ray lasers and other coherent X-ray sources, with an additional focus on supporting technologies, instrumentation and applications. The book highlights advances in a wide range of fields including laser and discharge-pumped plasma X-ray lasers, the injection and seeding of X-ray amplifiers, high-order harmonic generation and ultrafast phenomena, X-ray free electron lasers, X-ray and gamma-ray generation, X-ray ghost imaging, optics and metrology, X-rays and γ-rays for fundamental science, the practical implementation of X-ray lasers, XFELs and super-intense lasers, and the applications and industrial uses of X-ray lasers.

This book gives a comprehensive account of modern x-ray science, based on the use of synchrotron radiation and x-ray-free electron lasers (XFELs). It emphasizes the new capabilities of XFELs which extend the study of matter to the intrinsic timescales associated with the motion of atoms and chemical transformations and give birth to the new field of non-linear x-ray science. Starting with the historical understanding of the puzzling nature of light, it covers the modern description of the creation, properties, and detection of x-rays within quantum optics. It then presents the formulation of the interactions of x-rays with atomic matter, both, from semi-classical and first-principles quantum points of view. The fundamental x-ray processes and techniques, absorption, emission, Thomson, and resonant scattering (REXS and RIXS) are reviewed with emphasis on simple intuitive pictures that are illustrated by experimental results. Concepts of x-ray imaging and diffractive imaging of atomic and nano structures are discussed, and the quantum optics formulation of diffraction is presented that reveals the remarkable quantum substructure of light. The unique power of x-rays in providing atom and chemical-bond specific information and separating charge and spin phenomena through x-ray polarization (dichroism) effects are highlighted. The book concludes with the discussion of many-photon or non-linear x-ray phenomena encountered with XFELs, such as stimulated emission and x-ray transparency.

This thesis presents research on novel laboratory-scale synchrotron X-ray sources based on inverse Compton scattering and applications of their X-ray radiation using the Munich Compact Light Source (MuCLS) as an example. It provides an introduction to the theory of this laser-electron interaction, laser resonators and X-ray interactions with matter. On this basis, upgrades to the laser system including the development of a new laser optic, X-ray beam stabilisation and two techniques for fast X-ray energy switching of inverse Compton sources are presented. On the application side, the beamline, designed and developed for the inverse Compton X-ray source at the MuCLS, is described before various techniques and applications are demonstrated at this laboratory-scale synchrotron X-ray facility. Among them are K-edge subtraction imaging, X-ray phase contrast imaging and X-ray absorption spectroscopy. Additionally, a new X-ray microscopy technique, called full-field structured-illuminationsuper-resolution X-ray transmission microscopy, is presented.Apart from research conducted at the MuCLS, this thesis contains an in-depth overview on the state of the art of the various types of inverse Compton X-ray sources that have been realised so far. Accordingly, this thesis may serve as a guide and reference work for researchers working with inverse Compton X-ray sources as well as future users of such devices.

This thesis presents significant advances in the understanding of the statistical properties of undulator radiation via two experiments carried out in the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The first experiment studied the turn-to-turn fluctuations in the power of the radiation generated by an electron bunch. The magnitude of these fluctuations depends on the 6D phase-space distribution of the electron bunch. The author presents the most complete theoretical description of this effect to date, and shows that it can be used to measure some electron bunch parameters (e.g. its size and divergence). Remarkably, the performance of this technique improves for smaller bunches and shorter radiation wavelengths and it may, therefore, be particularly beneficial for existing state-of-the-art and next-generation low-emittance high-brightness x-ray synchrotron light sources. In the second experiment, a single electron was stored in the ring, emitting a photon only once per several hundred turns. In this regime, any classical interference-related collective effects were eliminated, and the quantum fluctuations could be studied in detail to search for possible deviations from the expected Poissonian photon statistics. In addition, the photocount arrival times were used to track the longitudinal motion of a single electron and to compare it with simulations. This served as an independent measurement of several dynamical parameters of the storage ring.

The physics of atomic inner shells has undergone significant advances in recent years. Fast computers and new experimental tools, notably syn­ chrotron-radiation sources and heavy-ion accelerators, have greatly enhan­ ced the scope of problems that are accessible. The level of research activity is growing substantially; added incentives are provided by the importance of inner-shell processes in such diverse areas as plasma studies, astrophysics, laser technology, biology, medicine, and materials science. The main reason for all this exciting activity in atomic inner-shell physics, to be sure, lies in the significance of the fundamental problems that are coming within grasp. The large energies of many inner-shell processes cause relativistic and quantum-electrodynamic effects to become strong. Unique opportunities exist for delicate tests of such phenomena as the screening of the electron self-energy and the limits of validity of the present form of the frequency-dependent Breit interaction, to name but two. The many-body problem, which pervades virtually all of physics, presents somewhat less intractable aspects in the atomic inner-shell regime: correlations are relatively weak so that they can be treated perturbatively, and the basic potential is simple and known! The dynamics of inner-shell processes are characterized by exceedingly short lifetimes and high transition rates that strain perturbation theory to its limits and obliterate the traditional separation of excitation and deexcitation. These factors are only now being explored, as are interference phenomena between the various channels.

Description based on print version record.