Author: Fritz, D.M.
Paper Title Page
MOPC08 Compact X-Ray and Bremsstrahlung Collimator for LCLS-II 68
  • N.A. Boiadjieva, D.M. Fritz, T. Rabedeau
    SLAC, Menlo Park, California, USA
  Beam collimation is crucial to maintaining machine and personnel safety during LCLS-II operation. The high density of optics and beam transport components needed to steer the beam to multiple beam lines places a premium on compact collimator design. This presentation discusses a compact collimator consisting of an X-ray beam power collimator, a burn through monitor (BTM) designed to detect failure of the X-ray beam collimator, and a Bremsstrahlung collimator. The collimator body is a monolith machined from CuCrZr (C18150) that eliminates costly braze operations and reduces assembly time and complexity. Sintered high thermal conductivity SiC is employed as the X-ray absorber with design provisions incorporated to permit the inclusion of additional absorbers (e.g. diamond). The allowed FEL beam power is limited to 100W. Finite element analyses ensure that the power absorber remains in safe temperature and stress regimes under the maximum power loading and smallest expected beam dimensions. The beam power will be limited via credited controls placed on the electron beam. Beam containment requirements stipulate the inclusion of a monitor to detect burn through events owing to absorber failure. The BTM is a gas-filled, thin wall vessel which, if illuminated by the beam, will burn through and release the contained gas and trip pressure switches that initiate beam shutdown. The beam absorber and BTM shadow the Bremsstrahlung collimator shielding after appropriate propagation of manufacturing, assembly, and installation tolerances. Tooling is developed to minimize assembly complexity and ensure minimal alignment errors.  
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About • paper received ※ 21 July 2021       paper accepted ※ 13 October 2021       issue date ※ 08 November 2021  
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