Advances in Free-Electron Radiation Sources and Particle Accelerators: Current Research and Future Directions

Dear Colleagues,

Free-electron radiation sources refer to electromagnetic radiation sources that are driven by free-electron beams exhibiting relatively high kinetic energies. These are typically generated by particle accelerators. Examples of these include free-electron lasers (FELs) and electromagnetic radiation sources based on transition radiation, Cherenkov radiation, and diffraction radiation (Smith–Purcell radiation). When compared with traditional laser sources, free-electron light sources exhibit the advantages of high power and broad spectral coverage, particularly across the spectral regions that traditional laser sources are unable to access, such as the terahertz, ultraviolet, and X-ray regions. This novel characteristic has a broad number of applications across multiple fields. Although these radiation schemes have been the subject of extensive research for decades, recent discoveries in the field of physics have led to increasing attention being paid to them in the past few years.

Particle accelerators find broad applications in fundamental scientific research and cutting-edge technologies. The conventional particle accelerator, using microwave technology, has encountered difficulties related to its high cost and large equipment. New designs for particle accelerators, such as the laser plasma wakefield accelerator, the laser dielectric accelerator, and the terahertz accelerator, have been proposed and trialed recently. These new accelerators can greatly increase the acceleration gradient and reduce the size of required equipment, indicating promising options for developing compact particle accelerators for the next generation.

This research topic will provide a platform for collating the latest research results, including theories, techniques, and applications, with respect to the following related topics.

The areas of interest include, but are not limited to, the following:

• Free-electron-driven coherent electromagnetic sources, including vacuum electron devices and free-electron lasers;
• Electromagnetic pulse radiation driven by electron beams, including transition radiation, Cherenkov radiation, and diffraction radiation;
• Accelerator on a chip, dielectric laser accelerators, and acceleration structures.
• Terahertz-driven accelerators, terahertz electron-guns, terahertz/microwave wakefield accelerators, other new guns, and advanced particle acceleration concepts;
• Electron bunch manipulation, laser free-electron beam modulation, and ultrafast electron-beam generation.

Prof. Dr. Weihao Liu
Dr. Javier Resta-Lopez
Dr. Yelong Wei
Dr. David Alesini
Guest Editors

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