Author: Schulte-Schrepping, H.
Paper Title Page
WEPF06 A Fast Switching Mirror Unit at FLASH 818
  • F. Perlick, J.D. Good, N. Leuschner, A.S. Ontoso, M. Sachwitz, L.V. Vu
    DESY Zeuthen, Zeuthen, Germany
  • H. Schulte-Schrepping
    DESY, Hamburg, Germany
  The Free Electron Laser (FLASH) at DESY Hamburg is a linac providing unique experimental opportunities to investigate the atomic structure and the properties of materials, nanoparticles, viruses and cells. At the experimental hall, the incoming FEL beam can be deflected towards five test sites by silicon mirrors mounted into vacuum vessels, of which one is operated in permanent switching mode, allowing the simultaneous use of the light at two different test sites. So far, the entire vacuum vessel with the mirror inside is moved into the beam by a linear motor. This results in high translatory inertia and, to compensate the vessel motion, requires vacuum bellows, which have a limited lifetime especially at higher switching frequencies. Therefore, in the recent design the mirror is shifted by piezo motors operated inside the vessel under ultra-high vacuum conditions. However, temperature measurements revealed that during continuous operation the motor reaches up to 90°C only when exposed to air, necessitating long breaks to allow it to cool. Therefore suitable cooling methods are being investigated to guarantee continuous operation of the motor under ultra-high vacuum conditions.  
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