| Paper |
Title |
Page |
| RPAT049 |
Numerical Studies on the Electro-Optic Sampling of Relativistic Electron Bunches
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3070 |
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- S. Casalbuoni, H. Schlarb, B. Schmidt, B. Steffen
DESY, Hamburg
- P. Schmüser, A. Winter
Uni HH, Hamburg
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Ultraviolet and X ray free electron lasers require sub-picosecond electron bunches of high charge density. Electro-optic sampling (EOS) is a suitable diagnostic tool for resolving the time structure of these ultrashort bunches. The transient electric field of the relativistic bunch induces a polarization anisotropy in a nonlinear crystal which is sampled by femtosecond laser pulses. In this paper, the EOS process is studied in detailed numerical calculations. The THz and the laser pulses are treated as wave packets which are propagated through the zinc telluride resp. gallium phosphide crystals. The effects of signal broadening and distortion are taken into account. The time resolution is limited by the lowest lattice oscillation frequency which amounts to 5.3 THz in ZnTe and 11 THz in GaP. The shortest bunch length which can be resolved with moderate distortion is about 200 fs (FWHM) in ZnTe and 100 fs in GaP.
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| RPAT050 |
Electro Optic Bunch Length Measurements at the VUV-FEL at DESY
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3111 |
| |
- B. Steffen, S. Casalbuoni, E.-A. Knabbe, H. Schlarb, B. Schmidt
DESY, Hamburg
- P. Schmüser, A. Winter
Uni HH, Hamburg
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For the operation of a SASE FEL, the longitudinal bunch length is one of the most critical parameters. At the superconducting linac of the VUV-FEL at DESY, we have installed an electro optic sampling (EOS) experiment to probe the time structure of the electric field of the bunches to better than 100 fs rms. The field-induced birefringence of a ZnTe crystal is detected by a femtosecond laser pulse (TiSa) and the time structure is measured by scanning the relative timing of the electron bunch and the TiSa pulse. A synchronization stability of better than 50 fs between laser and accelerator RF has been achieved. First results on the synchronization measurements and for the bunch length as function of the linac parameters are presented.
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