| Paper |
Title |
Page |
| MOPKF020 |
Proposal for a Sub-100 fs Electron Bunch Arrival-time Monitor for the VUV-FEL at DESY
|
345 |
| |
- H. Schlarb, S. Düsterer, J. Feldhaus, J. Hauschildt, R. Ischebeck, K. Ludwig, B. Schmidt, P. Schmüser, S. Simrock, B. Steffen, F. Van den Berghe, A. Winter
DESY, Hamburg
- P.H. Bucksbaum, A. Cavalieri, D. Fritz, S. Lee, D. Reis
Michigan University, Ann Arbor, Michigan
|
|
| |
For pump-probe experiments at the VUV-Free Electron Laser at DESY, an external optical laser system will be installed, capable of delivering ultra-short pulses of high intensity. The laser pulses with a center wavelength of 800 nm are synchronized with the VUV-FEL beam which covers the wavelength range between 6 nm and 80 nm. The expected pulse durations are typically 100 fs FWHM or below. For high-resolution pump-probe experiments a precise knowledge of the time difference between both pulses is mandatory. In this paper we describe the layout and the design of a high-precision electron bunch arrival time monitor based on an electro-optic technique. We present the numerical results of simulations that include: the laser propagation in a specifically designed demanding optical system, the laser transport through a 150 m long optical fibre, the electro-optically induced effect in different types of crystals and for different electron bunch shapes as well as the effects of wake fields on the co-propagating electric-fields and their impact on the observable signals.
|
|
| THPLT044 |
Measurement of the Transverse Coherence of the TTF Free Electron Laser
|
2577 |
| |
- R. Ischebeck, M. Tonutti
RWTH, Aachen
- J. Feldhaus, E. Saldin, E. Schneidmiller, K. Tiedtke, R. Treusch
DESY, Hamburg
- C. Gerth
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- P. Schmüser
Uni HH, Hamburg
- M.V. Yurkov
JINR, Dubna, Moscow Region
|
|
| |
The transverse coherence is important for many applications of a free electron laser (FEL). It depends on the inner structure of the electron bunch in the undulator, which is difficult to measure. It is therefore essential to determine the coherence properties of the FEL radiation directly. The coherence of the vacuum ultraviolet FEL at the TESLA Test Facility has been measured by recording the diffraction pattern of a double slit and measuring the visibility of the interference fringes. The experimental near field diffraction pattern is compared with a numerical model, taking into account the formation of the FEL radiation, the Fresnel diffraction in the near field zone and effects of the experimental set-up. Diffraction patterns have been recorded at various undulator lengths to measure the evolution of the transverse coherence along the undulator. This is compared to the expected evolution of the transverse radiation modes.
|
|