FERMI Free Electron Laser Research Articles

Erratum: Transverse emittance preservation during bunch compression in the Fermi free electron laser [Phys. Rev. ST Accel. Beams15, 020701 (2012)

Received 18 July 2012DOI:https://doi.org/10.1103/PhysRevSTAB.15.089901This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical Society

Publisher’s Note: Transverse emittance preservation during bunch compression in the Fermi free electron laser [Phys. Rev. ST Accel. Beams15, 020701 (2012)

Received 15 February 2012DOI:https://doi.org/10.1103/PhysRevSTAB.15.029901This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by American Physical Society

Transverse emittance preservation during bunch compression in the Fermi free electron laser

A characterization of the transverse emittance of a 200 pC, 6 ps long electron bunch has been performed in the Fermi@Elettra Free Electron Laser (FEL) first bunch compressor area. This region includes a magnetic bunch length compressor, diagnostics, and quadrupole magnets. The beam is time compressed in one stage, without linearization of the longitudinal phase space. Some growth of the normalized emittance has been measured in the compressor area. To understand this effect, we have investigated mechanisms of emittance growth such as coherent synchrotron radiation emission, chromatic aberration, and spurious dispersion. We show that careful optics control inside the compressor is essential for emittance growth reduction. The final configuration of one-stage magnetic compression limits the emittance to values below the design goal of 2 mm mrad, up to a compression factor of about 5. This machine configuration has been adopted to optimize FEL radiation output at wavelengths in the range 30--60 nm.

A velocity map imaging apparatus for gas phase studies at FERMI@Elettra

The design and evaluation of a velocity map imaging spectrometer specifically optimised for experiments at the FERMI free electron laser source are described. Optimisation of the set-up for the detection of high energy electrons (experimentally calibrated up to 45eV), reduction of scattered light and characterisation of the pulsed gas source are outlined. The instrument has been tested using synchrotron light at the GasPhase beamline at Elettra, the Italian synchrotron source, and the results are presented.