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

A special issue of Photonics (ISSN 2304-6732). This special issue belongs to the section "Optical Interaction Science".

Deadline for manuscript submissions: 31 October 2025 | Viewed by 3529

Special Issue Editors


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Guest Editor
School of Electronic Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China
Interests: terahertz technology; high power microwave technology; new particle accelerators; free electron laser theory and technology

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Guest Editor
Distinguished Researcher (Plan GenT), Institute of Materials Science, University of Valencia (ICMUV), Paterna, Spain
Interests: advanced beam dynamics studies; beam diagnostics and novel particle acceleration techniques
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, China
Interests: storage ring superconducting high frequency cavity; linear section room temperature high gradient accelerator cavity; new medium acceleration structure

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Guest Editor
FN-Istituto Nazionale di Fisica Nucleare, Frascati, Italy
Interests: beam dynamics; beam coupling impedance; linear accelerators; injection extraction kickers; RF acceleration structures; deflection cavities; and electron guns

Special Issue Information

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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Keywords

  • free-electron beam
  • electromagnetic radiation
  • light sources
  • laser-driven particle acceleration
  • laser free-electron beam interaction

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Published Papers (4 papers)

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Research

13 pages, 1812 KiB  
Article
Study of a Graphene Surface Plasmon Polariton-Based Dielectric Laser Accelerator
by Hongxiang Lin, Tianfa Liao, Xiaohui Wei, Wenyuan Wang, Juan Du and Yaoxuan Zhi
Photonics 2025, 12(4), 292; https://doi.org/10.3390/photonics12040292 - 21 Mar 2025
Viewed by 257
Abstract
Due to their high breakdown threshold and acceleration gradient, dielectric laser accelerators (DLAs) have become an important technical direction of accelerator miniaturization. In this study, an electron accelerator scheme based on graphene surface plasmon polaritons (SPPs) is proposed. The grating was designed to [...] Read more.
Due to their high breakdown threshold and acceleration gradient, dielectric laser accelerators (DLAs) have become an important technical direction of accelerator miniaturization. In this study, an electron accelerator scheme based on graphene surface plasmon polaritons (SPPs) is proposed. The grating was designed to be etched on the silica surface in the simulation, and a layer of graphene was modeled to cover the surface of the medium. The incident laser light in the simulation was configured to be coupled by the grating to generate surface plasmon polaritons (SPPs) on the graphene surface. According to the simulation results, a relatively large acceleration channel aperture and long acceleration length could be formed on the graphene surface using a mid-infrared laser; this provides a technical solution for increasing the beam current of a DLA. A 53.375 THz laser was incident on the surface of the accelerating structure to carry out tracking calculations on a 10 MeV electron beam. For the 100 μm accelerating structure, an energy gain of 0.105 MeV was achieved, and the acceleration gradient reached 1.05 GeV/m. Full article
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12 pages, 1371 KiB  
Article
Multi-Beam-Energy Control Unit Based on Triple-Bend Achromats
by Liuyang Wu, Zihan Zhu, Bingyang Yan, Jiawei Yan and Haixiao Deng
Photonics 2025, 12(3), 275; https://doi.org/10.3390/photonics12030275 - 17 Mar 2025
Viewed by 262
Abstract
X-ray free electron lasers (XFELs) are the new generation of particle accelerator-based light sources, capable of producing tunable, high-power X-ray pulses that are increasingly vital across various scientific disciplines. Recently, continuous-wave (CW) XFELs driven by superconducting linear accelerators have garnered significant attention due [...] Read more.
X-ray free electron lasers (XFELs) are the new generation of particle accelerator-based light sources, capable of producing tunable, high-power X-ray pulses that are increasingly vital across various scientific disciplines. Recently, continuous-wave (CW) XFELs driven by superconducting linear accelerators have garnered significant attention due to their ability to enhance availability by supporting multiple undulator lines simultaneously. In this paper, we introduce a novel delay system comprising four triple-bend achromats (TBAs). This delay system was combined with fast kickers and can be employed to generate electron beams on a bunch-to-bunch basis in a CW-XFEL facility. Based on the parameters of the Shanghai High-Repetition-Rate XFEL and Extreme Light Facility, start-to-end simulations demonstrate that the TBA-based delay system achieves excellent electron beam qualities while providing a wide beam-energy-tuning range from 1.39 to 8 GeV. Full article
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13 pages, 2725 KiB  
Article
Scintillation Properties of β-Ga2O3 Under the Excitation of Ultra-High-Charge Electron Bunches
by Yulan Liang, Jianhan Sun, Chaoyi Zhang, Tianqi Xu, Haoran Chen, Huaqing Huang, Chenhao Hua, Pengying Wan, Chuanwei Dai, Qingfan Wu, Juntao Liu, Lin Huang, Lin Lin, Huili Tang, Jianming Xue, Jun Xu, Senlin Huang, Bo Liu and Wenjun Ma
Photonics 2025, 12(2), 149; https://doi.org/10.3390/photonics12020149 - 12 Feb 2025
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Abstract
The performance of ultrafast scintillators under ultrahigh dose rate is highly important for applications utilizing brilliant radiation sources. In this work, the scintillation properties of β-Ga2O3, a high-performance ultrafast wide-bandgap semiconductor scintillator, are systematically investigated under dose rates of [...] Read more.
The performance of ultrafast scintillators under ultrahigh dose rate is highly important for applications utilizing brilliant radiation sources. In this work, the scintillation properties of β-Ga2O3, a high-performance ultrafast wide-bandgap semiconductor scintillator, are systematically investigated under dose rates of 107 to 109 Gy/s for the first time by employing ultrashort high-charge electron bunches (bunch charge from 500 fC to 50 pC) generated from a superconducting radio-frequency accelerator. Our results show that in spite of the ultrahigh dose rate, the scintillation intensity was still linearly proportional to the electron bunch charge. Lifetime analysis reveals a fast decay component ranging from 3 to 4 ns, along with an average lifetime of 20 ns. These findings establish a solid foundation for the application of β-Ga2O3 as the scintillation material for high-charge electron sources such as laser-wakefield accelerated electrons. Full article
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15 pages, 5042 KiB  
Article
Characterization of kHz Repetition Rate Laser-Driven Electron Beams by an Inhomogeneous Field Dipole Magnet Spectrometer
by Illia Zymak, Marco Favetta, Gabriele Maria Grittani, Carlo Maria Lazzarini, Gianfranco Tassielli, Annika Grenfell, Leonardo Goncalves, Sebastian Lorenz, Vanda Sluková, Filip Vitha, Roberto Versaci, Edwin Chacon-Golcher, Michal Nevrkla, Jiří Šišma, Roman Antipenkov, Václav Šobr, Wojciech Szuba, Theresa Staufer, Florian Grüner, Loredana Lapadula, Ezio Ranieri, Michele Piombino, Nasr A. M. Hafz, Christos Kamperidis, Daniel Papp, Sudipta Mondal, Pavel Bakule and Sergei V. Bulanovadd Show full author list remove Hide full author list
Photonics 2024, 11(12), 1208; https://doi.org/10.3390/photonics11121208 - 23 Dec 2024
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Abstract
We demonstrate a method to characterize the beam energy, transverse profile, charge, and dose of a pulsed electron beam generated by a 1 kHz TW laser-plasma accelerator. The method is based on imaging with a scintillating screen in an inhomogeneous, orthogonal magnetic field [...] Read more.
We demonstrate a method to characterize the beam energy, transverse profile, charge, and dose of a pulsed electron beam generated by a 1 kHz TW laser-plasma accelerator. The method is based on imaging with a scintillating screen in an inhomogeneous, orthogonal magnetic field produced by a wide-gap magnetic dipole. Numerical simulations were developed to reconstruct the electron beam parameters accurately. The method has been experimentally verified and calibrated using a medical LINAC. The energy measurement accuracy in the 6–20 MeV range is proven to be better than 10%. The radiation dose has been calibrated by a water-equivalent phantom, RW3, showing a linear response of the method within 2% in the 0.05–0.5 mGy/pulse range. Full article
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