| Paper |
Title |
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| TUPPH068 |
Coherent Micro-Bunching Radiation from Electron Bunches at FLASH in the 10 Micrometer Wavelength Range
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397 |
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- B. Schmidt, C. Behrens, S. Wesch
DESY, Hamburg
- H. Delsim-Hashemi, P. Schmüser
Uni HH, Hamburg
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At FLASH (DESY), a single shot broad band spectrometer THz spectrometer has been developed and installed which allows to measure the spectra of coherent bunch radiation for wavelengths between 2 micrometer and 300 micrometer. The spectrometer uses coherent transition radiation from an off-axis screen, extracted through a diamond window. Using this instrument, we found that the electron bunches emit coherent radiation in the regime 5 - 15 micrometer with an intensity which is almost independent of the bunch compressor strength. The radiation is present even for bunch lengths of several picoseconds. The shape of the spectrum indicates that the radiation is produced by a 'micro-bunching' of the charge density with a characteristic length in the 10 micrometer range. In this paper, we present systematic studies into the origin of this radiation, including its charge dependence, dependence on the photon injector parameters and on the strength of the magnetic chicanes and the bunch compression scheme.
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| THBAU02 |
Observation of 40 fs Synchronization of Electron Bunches for FELs
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490 |
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- F. Loehl, V. R. Arsov, M. Felber, L. Froehlich, K. E. Hacker, B. Lorbeer, F. Ludwig, K.-H. Matthiesen, H. Schlarb, B. Schmidt, A. Winter
DESY, Hamburg
- C. Behrens, S. Schulz, S. Wesch, J. Zemella
Uni HH, Hamburg
- W. Jalmuzna
TUL-DMCS, Łódź
- J. Szewinski
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
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State of the art XUV-light and X-Ray light sources like FLASH or the planned European XFEL produce light pulses with durations down to a few femtoseconds. To fully exploit the experimental opportunities offered by these light pulses, synchronization of the FEL facility on the same time scale is required. To meet these high demands, which can not be fulfilled by conventional, coaxial RF distribution schemes, at different laboratories, optical synchronization systems are developed. At FLASH, a prototype system consisting of a mode-locked, Er-doped fiber laser, two fiber links which are stabilized by optical cross-correlation to sub-10 fs, and two electro-optical bunch arrival time monitors with resolutions below 10 fs has been installed and tested recently. We report on our experience with the system and describe its use for an intra bunch train arrival time feedback with which we could improve the arrival time stability of the electron bunches from above 200 fs for the unstabilized case to 40 fs with the feedback active.
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