%0 Journal Article
%A Hoger, Tim
%A Rutkowski, Marco
%A Menneken, Martina
%A Düsterer, Stefan
%A Zacharias, Helmut
%A Siemer, Bjoern
%T Multiple free electron laser pulse illumination of a carbon coated silicon substrate
%J Proceedings of SPIE
%V 8777
%@ 0277-786X
%C Bellingham, Wash.
%I SPIE
%M PUBDB-2015-00458
%P 87770F
%D 2013
%Z © COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE)
%X The fourth generation of XUV-, soft x-ray- and x-ray-light sources, like the free electron lasers FLASH and FERMI@Elettra, leads to new seminal scientific findings and technical challenges. For the facilities the question of the beam transport is of utmost importance. To provide a good reflectivity over a large range of photon energies up to about 300 eV mostly carbon coated silicon mirrors illuminated under gracing incidence angle are mostly chosen. Thereby the coating for the mirrors must tolerate high light intensities at high photon energies and also high repetition rates. In the present experiment an amorphous carbon coated silicon substrate was illuminated at photon energies of 21 nm (58 eV) and an average pulse energy of  27 μJ. The ellipsoidal spot size of 300 μm × 600 μm at FLASH leads to a fluence of 0.019 J/cm2. The influence of multiple (100 - 20.000) light pulses to the coated surface is analyzed. Depending on the number of pulses a change in reflectivity is visible under a light microscope. Both an AFM profile and measurements with a profilometer yield no topological changes. The investigation of the illuminated spots with a microfocus Raman spectrometer shows a decrease of the carbon signal at higher pulse repetition rates.
%B SPIE Optics + Optoelectronics: Advances in X-ray Free-Electron Laser Instrumentation
%C 13 Apr 2015 - 16 Apr 2015, Prague (Czech Republic)
Y2 13 Apr 2015 - 16 Apr 2015
M2 Prague, Czech Republic
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000329577700012
%R 10.1117/12.2017248
%U https://bib-pubdb1.desy.de/record/205921