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Study of Compton backscattering with relativistic high-intense electron beam and single-pass free electron laser (FEL) is carried out to produce high-brightness short X-ray pulse. The single-pass FEL such as SASE is high power coherent light source and the wavelength of the FEL can be tuned changing magnetic field strength of wiggler or undulator continuously. In our study, the relativistic electron beam is generated using a linear accelerator, which is a driver for the FEL. The electron beam is used for both the Compton backscattering and the generation of SASE light. The preliminary experiment of X-ray generation based on Compton backscattering with high-intensity electron beam and infrared SASE light is planed using the L-band linear accelerator at the Institute of Scientific and Industrial Research (ISIR), Osaka University. We will describe the preliminary experiment and the result of numerical studies.

Accelerator-based light sources stimulated progress in photon science in a truly extraordinary manner. The spectral brightness of storage-ring-based facilities increased by three orders of magnitude every 10 years since the 1960s. The extreme peak brightness at single-pass free electron X-ray lasers with pulse durations variable between about 1 and 300 femtoseconds will allow transformative experiments in many areas of science. This article is an attempt to show how progress in accelerator science and technology stimulated advancement in photon science, by discussing a limited number of examples of work at third generation storage ring facilities and free electron lasers. Hopes for further improvements in specific beam properties are expressed.

In the last couple of years, free electron lasers (FELs) have been a remarkable success as fourth generation light sources all over the world. Operating in the SASE mode, they produce laser-like radiation in a broad wavelength range. Especially in the soft and hard X-ray ranges, these light sources open unique and completely new fields in physics and allow a vast range of applications in most scientific fields. This article gives an overview of the principles of FELs and the SASE process, discusses technological challenges and solutions, and presents an outlook for future developments.

We discuss recent results on soft and hard X-ray free electron lasers (FELs) and how they can be used to design and optimize the next generation of these sources of high brightness, coherent photons, with femtosecond pulse duration, or very narrow linewidth. In particular, we consider the experimental and theoretical progress in the electron beam generation and manipulation. These results, when combined with the successful development of powerful simulation codes, can be used to design optimized, high intensity sources of coherent photons, and to reduce their size and cost.

Fourth generation light sources based on high gain free electron lasers require production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake field effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, and hence the design of the injector and its operation constitute the leading edge for high quality beam production and for the success of the future light sources. RF and DC guns, cathode materials, laser pulse shaping and sub-picosecond synchronization systems are evolving toward a mature technology to produce high quality and stable beams. Nevertheless, reduction of thermal emittance, damping of emittance oscillations and bunch compression are still the main issues and challenges for injector designs. With the advent of energy recovery linacs, superconducting RF guns have been also considered in many new projects as a possible electron source operating in CW mode. An overview of recent advancements and future perspectives of high performance electron injectors are presented in this article.

Novel laser-powered accelerating structures at the miniaturized scale of an optical wavelength $(\sim 1\mu \text{m})$ open a pathway to high repetition rate, attosecond scale electron bunches that can be accelerated with gradients exceeding 1 GeV/m. Although the theoretical and computational study of dielectric laser accelerators dates back many decades, recently the first experimental realizations of this novel class of accelerators have been demonstrated. We review recent developments in fabrication, testing, and demonstration of these micron scale devices. In particular, prospects for applications of this accelerator technology are evaluated.

Accelerator-based X-ray sources have contributed uniquely to the physical, engineering and life sciences. There has been a constant development of the sources themselves as well as of the necessary X-ray optics and detectors. These advances have combined to push X-ray science to the forefront in structural studies, achieving atomic resolution for complex protein molecules, to meV scale dynamics addressing problems ranging from geoscience to high-temperature superconductors, and to spatial resolutions approaching 10nm for elemental mapping as well as three-dimensional structures. Here we discuss accelerator-based photon science in the frame of imaging and highlight the importance of optics, detectors and computation/data science as well as the source technology. We look to a bright future for X-ray systems, integrating all components from accelerator sources to digital image production algorithms, and highlight aspects that make them unique scientific tools.

Accelerator-based X-ray sources have contributed uniquely to the physical, engineering and life sciences. There has been a constant development of the sources themselves as well as of the necessary X-ray optics and detectors. These advances have combined to push X-ray science to the forefront in structural studies, achieving atomic resolution for complex protein molecules, to meV scale dynamics addressing problems ranging from geoscience to high-temperature superconductors, and to spatial resolutions approaching 10nm for elemental mapping as well as three-dimensional structures. Here we discuss accelerator-based photon science in the frame of imaging and highlight the importance of optics, detectors and computation/data science as well as the source technology. We look to a bright future for X-ray systems, integrating all components from accelerator sources to digital image production algorithms, and highlight aspects that make them unique scientific tools.

Novel laser-powered accelerating structures at the miniaturized scale of an optical wavelength (∼1μm) open a pathway to high repetition rate, attosecond scale electron bunches that can be accelerated with gradients exceeding 1 GeV/m. Although the theoretical and computational study of dielectric laser accelerators dates back many decades, recently the first experimental realizations of this novel class of accelerators have been demonstrated. We review recent developments in fabrication, testing, and demonstration of these micron scale devices. In particular, prospects for applications of this accelerator technology are evaluated.

Shortening the laser pulse length, ultimately toward the monocycle time scale, is one of the most important subject in the laser technology. Although this is also the case for free electron lasers (FELs), there is a fundamental and theoretical lower limit to the attainable pulse length in FELs, which comes from the so-called slippage effect intrinsic to the FEL amplification process. In this paper, a new FEL concept, which has been proposed to overcome the theoretical limit and realize monocycle FELs, is explained together with reviewing two schemes to implement the concept in the actual FEL system.

Accelerator-based light sources stimulated progress in photon science in a truly extraordinary manner. The spectral brightness of storage-ring-based facilities increased by three orders of magnitude every 10 years since the 1960s. The extreme peak brightness at single-pass free electron X-ray lasers with pulse durations variable between about 1 and 300 femtoseconds will allow transformative experiments in many areas of science. This article is an attempt to show how progress in accelerator science and technology stimulated advancement in photon science, by discussing a limited number of examples of work at third generation storage ring facilities and free electron lasers. Hopes for further improvements in specific beam properties are expressed.

In the last couple of years, free electron lasers (FELs) have been a remarkable success as fourth generation light sources all over the world. Operating in the SASE mode, they produce laser-like radiation in a broad wavelength range. Especially in the soft and hard X-ray ranges, these light sources open unique and completely new fields in physics and allow a vast range of applications in most scientific fields. This article gives an overview of the principles of FELs and the SASE process, discusses technological challenges and solutions, and presents an outlook for future developments.

We discuss recent results on soft and hard X-ray free electron lasers (FELs) and how they can be used to design and optimize the next generation of these sources of high brightness, coherent photons, with femtosecond pulse duration, or very narrow linewidth. In particular, we consider the experimental and theoretical progress in the electron beam generation and manipulation. These results, when combined with the successful development of powerful simulation codes, can be used to design optimized, high intensity sources of coherent photons, and to reduce their size and cost.

Fourth generation light sources based on high gain free electron lasers require production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake field effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, and hence the design of the injector and its operation constitute the leading edge for high quality beam production and for the success of the future light sources. RF and DC guns, cathode materials, laser pulse shaping and sub-picosecond synchronization systems are evolving toward a mature technology to produce high quality and stable beams. Nevertheless, reduction of thermal emittance, damping of emittance oscillations and bunch compression are still the main issues and challenges for injector designs. With the advent of energy recovery linacs, superconducting RF guns have been also considered in many new projects as a possible electron source operating in CW mode. An overview of recent advancements and future perspectives of high performance electron injectors are presented in this article.