"Flying" RF-undulators for Compton FELs: Design, Simulations and Testing

• Published in: 2021 Photonics & Electromagnetics Research Symposium (PIERS) pp. 1054 - 1059
• Main Authors: Vikharev, A. A., Kuzikov, S. V., Peskov, N. Yu, Proyavin, M. D., Savilov, A. V.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 21.11.2021
• Subjects: Electrodynamics; Electron beams; Prototypes; Radio frequency; Scattering; Sensitivity; Waveguide components
• ISSN: 2694-5053
• DOI: 10.1109/PIERS53385.2021.9694869

Present paper is devoted to the original concept of Compton FEL-scattrons, which is under development now at the IAP RAS (Nizhny Novgorod). The aims of this concept are to reduce energy of driving relativistic electron beam, to increase the efficiency of electron-wave interaction and to achieve relative compactness of the FEL. For this concept a new type of RF undulator, the so-called "flying" undulator was proposed. As an electrodynamic system of such RF-undulator, a section of helically corrugated cylindrical waveguide can be used that forms a microwave pulse (normal wave), which synchronously propagate with the electron bunch, and contain counter-propagating partial wave, which pumps operating oscillations of this bunch and, thus, stimulated scattering of this RF-pulse with a high Doppler frequency up-conversion in the FEL-scattron. Additionally, further enhance of the FEL efficiency can be achieved when profiling parameters of "flying" RF undulators to implement original multi-stage "non-resonant" trapping regime. In this paper we present the design parameters, results of simulations and "cold" electrodynamical tests of regular and profiled "flying" undulators operating at the Ka and W frequency bands.