Author: Dziarzhytski, S.
Paper Title Page
MOP010 The Photon Beam Loss Monitors as a Part of Equipment Protection System at European XFEL 37
 
  • N. Gerasimova, H. Sinn
    XFEL. EU, Hamburg, Germany
  • S. Dziarzhytski, R. Treusch
    DESY, Hamburg, Germany
  
  For the X-ray beam trans­port sys­tems, the prob­lem of po­ten­tial dam­age to the equip­ment by mis-steered pho­ton beam emerged with ad­vent of pow­er­ful X-ray FELs. In par­tic­u­lar high rep­e­ti­tion rate ma­chines as Eu­ro­pean XFEL, where not only fo­cused beam can pro­duce ab­la­tion, but even un­fo­cused beam can melt the beam­line com­po­nents while ma­chine op­er­ates in multi­bunch mode, de­mand for im­ple­men­ta­tion of equip­ment pro­tec­tion. Here we re­port on de­vel­op­ment of pho­ton beam loss mon­i­tors at Eu­ro­pean XFEL fa­cil­ity. The pho­ton beam loss mon­i­tors will react on the mis-steered pho­ton beam and in­ter­face the ma­chine pro­tec­tion sys­tem. The pro­to­type com­prises the vac­uum cham­ber with flu­o­res­cence crys­tals po­si­tioned out­side the pho­ton beam­path. The fast sub-hun­dred ns flu­o­res­cence in­duced by mis-steered beam can be de­tected by pho­to­mul­ti­plier tube al­low­ing for in­tra-train re­ac­tion of ma­chine pro­tec­tion sys­tem. First tests have been car­ried out at FLASH and shown the fea­si­bil­ity of de­tec­tion based on PMT-de­tected flu­o­res­cence. In ad­di­tion to ef­fi­cient YAG:Ce crys­tal, the ro­bust low-Z ma­te­r­ial as CVD mi­cro­crys­talline di­a­monds has shown a po­ten­tial to be used as flu­o­res­cence crys­tals.  
 
TUB04 Operation of FLASH with Short SASE-FEL Radiation Pulses 342
 
  • J. Rönsch-Schulenburg, E. Hass, N.M. Lockmann, T. Plath, M. Rehders, J. Roßbach
    Uni HH, Hamburg, Germany
  • G. Brenner, S. Dziarzhytski, T. Golz, H. Schlarb, B. Schmidt, E. Schneidmiller, S. Schreiber, B. Steffen, N. Stojanovic, S. Wunderlich, M.V. Yurkov
    DESY, Hamburg, Germany
  
  Funding: The project has been supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301
This paper de­scribes the ex­per­i­men­tal ac­tiv­ity on the gen­er­a­tion of very short FEL pulses in the soft x-ray range in the SASE-mode at the high-gain free-elec­tron laser FLASH [1, 2]. The key el­e­ment, a photo-in­jec­tor laser which is able to gen­er­ate laser pulses of about 2 ps FWHM has been op­ti­mized and com­mis­sioned. It al­lows the gen­er­a­tion of shorter bunches with low bunch charge (of up to 200 pC) di­rectly at the photo-cath­ode. Ini­tially shorter in­jec­tor laser pulses and thus shorter bunches eases the re­quired bunch com­pres­sion fac­tor for short pulses below 10 fs du­ra­tion which makes op­er­a­tion of the elec­tron beam for­ma­tion sys­tem to be more ro­bust with re­spect to jit­ters and col­lec­tive ef­fects. As a re­sult, over­all sta­bil­ity of SASE FEL per­for­mance is im­proved. In the op­ti­mal case sin­gle-spike op­er­a­tion can be achieved. In this paper the ex­per­i­men­tal re­sults on pro­duc­tion of short elec­tron bunches and the SASE per­for­mance using the new in­jec­tor laser will be shown and the mea­sured elec­tron bunch and FEL ra­di­a­tion prop­er­ties are dis­cussed. In ad­di­tion, op­ti­miza­tions of bunch di­ag­nos­tics for low charge and short bunches are dis­cussed. 		 
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