Enhancement of FEM radiation by prebunching of the e-beam (stimulated super-radiance)

M. Arbel*, A. L. Eichenbaum, H. Kleinman, I. M. Yakover, A. Abramovich, Y. Pinhasi, Y. Luria, M. Tecimer, A. Gover

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


An electron beam (e-beam) prebunched at the synchronous FEM frequency and traversing through a waveguide, located coaxially with a magnetic undulator, emits coherent radiation at the bunching frequency. Introduction of both a premodulated e-beam and a radio-frequency (r.f.) signal at the same frequency at the input of the waveguide can lead to more efficient interaction, and thus more power can be extracted from the electron beam. In order to achieve this, the density modulation of the electron beam should be at an appropriate phase with respect to the r.f. signal. We report a first experimental demonstration of the influence of the phase difference between the r.f. input signal and the fundamental component of the density modulation of the e-beam on the radiated power in a Free-Electron Maser (FEM). Our experimental system allows control of the current density modulation, of the r.f. input power level, in the undulator region and of the phase between that r.f. input and the modulation of the e-beam. A comparison between measured radiation power with that predicted by theory for various phase differences, current density modulation, and r.f. signal levels, was made. Good correlation was obtained.

Original languageEnglish
Pages (from-to)303-307
Number of pages5
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Issue number1-3
StatePublished - 21 Nov 2001
Event22nd International Free Electron Laser Conference (FEL 2000) - Durham, NC, United States
Duration: 13 Aug 200018 Aug 2000


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