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otr

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MOPP038 Transverse Electron Beam Diagnostics at the VUV-FEL at DESY emittance, electron, linac, undulator 122
 
  • K. Honkavaara, F. Loehl
    Uni HH, Hamburg
  • M. Castellano, G. Di Pirro
    INFN/LNF, Frascati (Roma)
  • L. Catani, A. Cianchi
    INFN-Roma II, Roma
  • D. Noelle, S. Schreiber
    DESY, Hamburg
  • M. Sachwitz, E.S. sombrowski
    DESY Zeuthen, Zeuthen
  
 

The VUV-FEL is a new free electron laser user facility under commissioning at DESY. High demands on the electron beam quality require sophisticated beam diagnostics tools and methods. At the VUV-FEL, the transverse characterization of the electron beam is performed using optical transition radiation (OTR) monitors and wirescanners. This paper refers the concepts, analysis, and results of these measurements. The main emphasis is put on the emittance measurements, in which we have regularly observed small rms emittances around 1.4 mm mrad for 90% of a 1 nC bunch at 127 MeV beam energy.

   
    
THPP055 Nonintercepting Electron Beam Diagnostics Based on Optical Diffraction Radiation for X-Ray FELs radiation, dipole, electron, x-ray 604
 
  • A.H. Lumpkin, W. Berg, N. Sereno, B.X. Yang, C. Yao
    ANL, Argonne, Illinois
  • D.W. Rule
    NSWC, West Bethesda, Maryland
  
 

Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.

The challenge of providing nonintercepting beam diagnostics that address transverse parameters such as beam size and divergence in a linear transport line has been met. We have successfully used near-field imaging of optical diffraction radiation (ODR) from a 7-GeV electron beam passing near a single edge of a conducting screen to obtain beam size for the first time [1]. In this case appreciable visible wavelength ODR is emitted for impact parameters of 1 to 2 mm, values that are close to gamma times the reduced observation wavelength. We have now upgraded our imaging system to include an intensified camera; selectable bandpass filters, neutral density filters, and polarizers; a steering mirror; and an optical lens setup that provides either near-field or far-field imaging. The ODR has been obtained in both the single-edge mode and aperture mode with a single pulse of 3.3 nC. Beam-size resolution in the 20-50 micron regime is projected while beam position resolution to 10 microns with a smaller beam and higher optical magnification should be feasible with near-field imaging. Applications to high-energy accelerators that drive x-ray FELs or energy recovering linacs for light sources should be possible.

[1] A.H. Lumpkin et al., "First Near-Field Imaging of Optical Diffraction Radiation Generated by a 7-GeV Electron Beam,” submitted to Phys. Rev. Lett., May 4, 2005.