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| WEPPH001 |
Femtosecond CPA-based Laser Research & Development Program for Photoinjectors
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- D. Garzella, S. Grabielle, J-F. Hergott, Ph. Hollander, D. Jourdain, F. Lepetit, M. Perdrix, O. Tcherbakoff, O. B. Gobert
CEA, Gif-sur-Yvette
- T. Oksenhendler
FASTLITE, Palaiseau
- G. D. Rovera
LNE-SYRTE, Paris
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High Brightness, electron Linac-based light sources call for synergy with conventional high energy laser sources. Indeed, photoinjectors R&D needs lasers R&D. The Ti:S lasers based on Chirped Pulse Amplification (CPA) techniques can supply the requested light features for operating with such accelerator systems, provided that one can shape and control the laser pulses in the temporal and spatial domain. In the EUROFEL European program framework, the investigations performed by the LUCA/PLFA team at the Saclay Laser Interaction Center are twofold : - Temporal and spatial shaping of fs UV laser pulses. Temporal beam shaping is performed through an amplitude and phase modulation in the pulse spectral domain by means of an active programmable system. Transverse pulse shaping is achieved with a passive optical system based on aspheric optics. A combination of both techniques allows one to obtain "beer can" shaped photoelectron bunches easily. -Investigations in laser/LINAC synchronization and timing distribution. Optical experimental techniques are used to measure the drift and the jitter at the output laser system whose oscillator repetition rate is locked on a Rb atomic clock. In the present paper the major numerical studies and experimental results are presented. Further considerations on the benefits and the limits brought by these experimental techniques will be discussed.
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| WEPPH045 |
Femtosecond-level Timing Instabilities on CPA-based Laser Systems
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- D. Garzella, O. B. Gobert, J-F. Hergott, Ph. Hollander, D. Jourdain, F. Lepetit, M. Perdrix, O. Tcherbakoff
CEA, Gif-sur-Yvette
- G. D. Rovera
LNE-SYRTE, Paris
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An essential feature for operating accelerator-based light sources is the Timing and Synchronization system. This is necessary in photoelectron bunches generation, in order to synchronize the drive laser with the RF of the accelerating cavity, or in the seeding of an external laser in an undulator. A unique Timing Standard is also required by the end-users for setting up time resolved pump-probe experiments. These various needs call for sub-ps synchronization level. The LUCA/PLFA team at the Saclay Laser Interaction Center (SLIC) developed an experimental setup to lock the repetition rate of the oscillator of the CPA-based laser system on a Rb atomic clock. An analysis of the temporal characteristics of the system without this stabilization is presented, showing the influence of the environmental parameters (temperature, atmospheric pressure and humidity) on the oscillator rate. The results obtained with the stabilization system on, are then presented and analyzed using classical methods (Allan variance and phase power spectral density). In order to investigate experimentally the temporal jitter and drift which can appear inside the laser system, a Fourier Transform Spectral Interferometry experiment has been set up. This experiment should give us an accuracy of tens of fs. Detailed results and analysis will be presented.
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