Passive Ballistic Microbunching of Nonultrarelativistic Electron Bunches Using Electromagnetic Wakefields in Dielectric-Lined Waveguides

• Published in: Physical review letters 2019-02, Vol.122 (4), p.044801-044801, Article 044801
• Main Authors: Lemery, F, Piot, P, Amatuni, G, Boonpornprasert, P, Chen, Y, Good, J, Grigoryan, B, Groß, M, Krasilinikov, M, Lishilin, O, Loisch, G, Oppelt, A, Philipp, S, Qian, H, Renier, Y, Stephan, F, Zagorodnov, I
• Format: Article
• Language: English
• Subjects: Density; Electromagnetic radiation; Electron beams; Electron diffraction; Electrons; Excitation; Light diffraction; Modulation; Waveguides
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.122.044801

Temporally modulated electron beams have a wide array of applications ranging from the generation of coherently enhanced electromagnetic radiation to the resonant excitation of electromagnetic wakefields in advanced-accelerator concepts. Likewise producing low-energy ultrashort microbunches could be useful for ultrafast electron diffraction and new accelerator-based light-source concepts. In this Letter we propose and experimentally demonstrate a passive microbunching technique capable of forming a picosecond bunch train at ∼6  MeV. The method relies on the excitation of electromagnetic wakefields as the beam propagates through a dielectric-lined waveguide. Owing to the nonultrarelativistic nature of the beam, the induced energy modulation eventually converts into a density modulation as the beam travels in a following free-space drift. The modulated beam is further accelerated to ∼20  MeV while preserving the imparted density modulation.