L Giannessi and P Musumeci 2006 New J. Phys. 8 294 doi:10.1088/1367-2630/8/11/294
The free-electron laser harmonic cascade
Focus on Accelerator and Beam PhysicsL Giannessi1,3 and P Musumeci2
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Free-electron laser (FEL) devices based on a sequence of amplifiers with a harmonic relation between the resonant frequencies of each section have been proposed to extend to shorter wavelengths the FEL operating range. Because of the practical limit on the tunability of undulator magnets, the e-beam energy still represents the main constraint on the shortest reachable wavelength of the cascade. In this paper, we propose a scheme where the undulators of the cascade are tuned at different, not-harmonic, fundamental frequencies having instead one of the higher order harmonics at a common frequency. A short and intense seed pulse in such a system creates a superradiant pulse which harmonically seeds the following undulator at the common multiple frequency. The microbunching at the higher harmonic in the second undulator is enhanced by the modulation of the previous undulator so that lasing at shorter wavelengths may be obtained with a relatively low-energy electron beam.
- PACS
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles
- Subjects
- Dates
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Issue 11 (November 2006)
Received 8 June 2006
Published 28 November 2006
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The free-electron laser harmonic cascade
L Giannessi and P Musumeci 2006 New J. Phys. 8 294
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