Author: Tanaka, M.
Paper Title Page
TUPD12 Development of Non-Invasive Electron Beam Position Monitor Based on Coherent Diffraction Radiation from a Slit 442
 
  • Y. Taira, R. Kuroda, M. Tanaka, H. Toyokawa
    AIST, Ibaraki, Japan
  • K. Sakaue
    Waseda University, Tokyo, Japan
  • H. Tomizawa
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  Funding: This work was supported by Grants-in-Aid for Scientific Research (26246046).
Diffraction radiation (DR), which is closely related to transition radiation, is emitted when an electron passes near an edge or interface between two media with different dielectric constants. Theoretical and experimental investigation of DR is widely performing for a non-intercepting electron beam diagnostic. We have developed an electron bunch length and a beam position monitor using a coherent diffraction radiation (CDR), which is in the range of sub-millimeter wavelength. The frequency spectrum of CDR depends on a form factor expressed as the Fourier transform of the longitudinal particle distribution. We have measured the spatial intensity distribution of CDR emitted from the metallic edge with a terahertz camera. Total intensity passing through band pass filters (BPFs) was decreased as the transmission frequency of BPFs is increased up to 6 THz. The result indicates that the bunch length is few hundreds of femtosecond. A detailed data analysis is now performing. On the other hand, we have measured the intensity distribution of CDR emitted from the metallic rectangular slit. Bow-tie intensity distribution, aligned along the perpendicular direction to the slit edge, was measured with the terahertz camera. Moreover, when the electron beam did not pass through the center of the slit, an asymmetrical intensity distribution appeared. This asymmetry is due to the pre-wave zone effect. In short, we can found the beam position to the slit by measuring the asymmetry. In this conference, we will present the experimental results.
 
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