TY - JOUR
T1 - Microfocusing of the FERMI@Elettra FEL beam with a K-B active optics system
T2 - Spot size predictions by application of the WISE code
AU - Raimondi, L.
AU - Svetina, C.
AU - Mahne, N.
AU - Cocco, D.
AU - Abrami, A.
AU - De Marco, M.
AU - Fava, C.
AU - Gerusina, S.
AU - Gobessi, R.
AU - Capotondi, F.
AU - Pedersoli, E.
AU - Kiskinova, M.
AU - De Ninno, G.
AU - Zeitoun, P.
AU - Dovillaire, G.
AU - Lambert, G.
AU - Boutu, W.
AU - Merdji, H.
AU - Gonzalez, A. I.
AU - Gauthier, D.
AU - Zangrando, M.
PY - 2013/5/11
Y1 - 2013/5/11
N2 - FERMI@Elettra, the first seeded EUV-SXR free electron laser (FEL) facility located at Elettra Sincrotrone Trieste has been conceived to provide very short (10-100 fs) pulses with ultrahigh peak brightness and wavelengths from 100 nm to 4 nm. A section fully dedicated to the photon transport and analysis diagnostics, named PADReS, has already been installed and commissioned. Three of the beamlines, EIS-TIMEX, DiProI and LDM, installed after the PADReS section, are in advanced commissioning state and will accept the first users in December 2012. These beam lines employ active X-ray optics in order to focus the FEL beam as well as to perform a controlled beam-shaping at focus. Starting from mirror surface metrology characterization, it is difficult to predict the focal spot shape applying only methods based on geometrical optics such as the ray tracing. Within the geometrical optics approach one cannot take into account the diffraction effect from the optics edges, i.e. the aperture diffraction, and the impact of different surface spatial wavelengths to the spot size degradation. Both these effects are strongly dependent on the photon beam energy and mirror incident angles. We employed a method based on physical optics, which applies the Huygens-Fresnel principle to reflection (on which the WISE code is based). In this work we report the results of the first measurements of the focal spot in the DiProI beamline end-station and compare them to the predictions computed with Shadow code and WISE code, starting from the mirror surface profile characterization.
AB - FERMI@Elettra, the first seeded EUV-SXR free electron laser (FEL) facility located at Elettra Sincrotrone Trieste has been conceived to provide very short (10-100 fs) pulses with ultrahigh peak brightness and wavelengths from 100 nm to 4 nm. A section fully dedicated to the photon transport and analysis diagnostics, named PADReS, has already been installed and commissioned. Three of the beamlines, EIS-TIMEX, DiProI and LDM, installed after the PADReS section, are in advanced commissioning state and will accept the first users in December 2012. These beam lines employ active X-ray optics in order to focus the FEL beam as well as to perform a controlled beam-shaping at focus. Starting from mirror surface metrology characterization, it is difficult to predict the focal spot shape applying only methods based on geometrical optics such as the ray tracing. Within the geometrical optics approach one cannot take into account the diffraction effect from the optics edges, i.e. the aperture diffraction, and the impact of different surface spatial wavelengths to the spot size degradation. Both these effects are strongly dependent on the photon beam energy and mirror incident angles. We employed a method based on physical optics, which applies the Huygens-Fresnel principle to reflection (on which the WISE code is based). In this work we report the results of the first measurements of the focal spot in the DiProI beamline end-station and compare them to the predictions computed with Shadow code and WISE code, starting from the mirror surface profile characterization.
KW - Free electron laser
KW - Fresnel diffraction
KW - K-B mirrors
KW - Wavefront propagation
U2 - 10.1016/j.nima.2012.11.039
DO - 10.1016/j.nima.2012.11.039
M3 - Article
AN - SCOPUS:84891865731
SN - 0168-9002
VL - 710
SP - 131
EP - 138
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
ER -