Control of the Polarization of a Vacuum-Ultraviolet, High-Gain, Free-Electron Laser
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Enrico Allaria
- Function : Author
Bruno Diviacco
- Function : Author
Benoît Mahieu
- Function : Author
- PersonId : 19544
- IdHAL : benoit-mahieu
- ORCID : 0000-0002-5439-0433
- IdRef : 170377431
Jens Viefhaus
- Function : Author
Guillaume Lambert
- Function : Author
- PersonId : 4339
- IdHAL : guillaume-lambert
- IdRef : 129226882
Eugenio Ferrari
- Function : Author
Jens Buck
- Function : Author
Markus Ilchen
- Function : Author
Boris Vodungbo
- Function : Author
- PersonId : 4340
- IdHAL : boris-vodungbo
- ORCID : 0000-0002-0168-9343
- IdRef : 130370444
Cristian Svetina
- Function : Author
- PersonId : 764652
- ORCID : 0000-0003-2399-4426
Simone Di Mitri
- Function : Author
Mauro Trovó
- Function : Author
William M. Fawley
- Function : Author
Primoz R. Rebernik
- Function : Author
Cesare Grazioli
- Function : Author
Barbara Ressel
- Function : Author
Tommaso Mazza
- Function : Author
Leif Glaser
- Function : Author
Patrick Gessler
- Function : Author
Michael Meyer
- Function : Author
Lorenzo Raimondi
- Function : Author
Emanuele Pedersoli
- Function : Author
- PersonId : 774255
- ORCID : 0000-0003-0572-6735
Oksana Plekan
- Function : Author
Miltcho B. Danailov
- Function : Author
Alexander Demidovich
- Function : Author
Alessandro Abrami
- Function : Author
Philippe Zeitoun
- Function : Author
- PersonId : 4358
- IdHAL : philippe-zeitoun
- IdRef : 08195574X
Abstract
The two single-pass, externally seeded free-electron lasers (FELs) of the FERMI user facility are designed around Apple-II-type undulators that can operate at arbitrary polarization in the vacuum ultraviolet-to-soft x-ray spectral range. Furthermore, within each FEL tuning range, any output wavelength and polarization can be set in less than a minute of routine operations. We report the first demonstration of the full output polarization capabilities of FERMI FEL-1 in a campaign of experiments where the wavelength and nominal polarization are set to a series of representative values, and the polarization of the emitted intense pulses is thoroughly characterized by three independent instruments and methods, expressly developed for the task. The measured radiation polarization is consistently >90% and is not significantly spoiled by the transport optics; differing, relative transport losses for horizontal and vertical polarization become more prominent at longer wavelengths and lead to a non-negligible ellipticity for an originally circularly polarized state. The results from the different polarimeter setups validate each other, allow a cross-calibration of the instruments, and constitute a benchmark for user experiments.