| Paper | Title | Page |
|---|---|---|
| THPPH050 | Beat-Wave Laser-Driven Photoinjector for Superradiance Free-Electron Laser | 699 |
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Electron bunching plays a crucial role in a radiative emission process. Every free-electron laser (FEL) more or less relies on periodic bunching of electrons to build up radiation power. In this paper, we present our study on the generation and acceleration of periodically bunched electrons in a photo-injector. The idea is to use a laser beat wave to induce a density modulated photocurrent from a photocathode, which is subsequently accelerated to a relativistic speed. The electron micro-bunches in the density modulated current repeat at the laser beat frequency. Our computer simulations using the ASTRA* code show remarkable modulation contrast in > 50 A output current of a 4 MeV RF photocathode gun and a 20 MeV photocathode accelerator. With slight modifications to a conventional photocathode-gun driver laser, a UV beat-wave laser with a variable beat frequency can be implemented by combining two chirped laser pulses with a variable time delay. We will report our experimental progress toward realizing such a new technique in a compact superradiance Smith-Purcell FEL at THz frequencies.
* K. Floettmann, ASTRA User Manual, http://www.desy.de/mpyflo/Astra\dokumentation |