Author: Vinokurov, N.A.
Paper Title Page
TUC01 Polarization Control of Storage Ring FELs Using Cross Polarized Helical Undulators 235
 
  • J. Yan, H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • S. Huang
    PKU, Beijing, People's Republic of China
  • J.L. Li
    IHEP, Beijing, People's Republic of China
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • N.A. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  
  For more than two decades, accelerator researchers have been working to gain control of polarization of synchrotron radiation and FELs using non-optical means. In 2005, the first experimental demonstration of polarization control of an FEL beam was realized with the Duke storage-ring FEL. With the recent upgrade of the undulator system, the Duke FEL can be operated with up to four helical undulators simultaneously. Using two sets of helical undulators with opposite helicities, for the first time, we have demonstrated full polarization control of a storage ring FEL. First, the helicity switch of the FEL beam has been realized with good lasing up to a few Hz. Second, the linearly polarized FEL beam has been generated with a high degree of polarization (Plin>0.95). The FEL polarization direction can be fully controlled using a buncher magnet. Furthermore, the use of non-optical means to control the FEL polarization allows us to extend polarization control to gamma-ray beams generated using Compton scattering. This has been experimentally demonstrated with the production of linearly polarized Compton gamma-ray beams with rotatable polarization direction based upon helical undulators.  
slides icon Slides TUC01 [5.921 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUC01  
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WEB02
 Characterization of Electron Bunches in Ultrafast Electron Diffraction Beamlines at KAERI  
 
  • H.W. Kim, I.H. Baek, K.H. Jang, Y.U. Jeong, K. Lee, J.H. Nam, N.A. Vinokurov
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • I.H. Baek, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, Y.-C. Kim, K. Lee, S.V. Miginsky, J.H. Nam, S. Park, S. Setiniyaz
    KAERI, Daejon, Republic of Korea
  • R. Fabian, H. Ihee, J. Kim, K.Y. Oang, H. Yang
    KAIST, Daejeon, Republic of Korea
  • K.W. Kim
    Chung Buk National University, Cheongju, Republic of Korea
  • S.V. Miginsky, N.A. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  
  Ultrashort electron bunches from ultrafast electron diffraction (UED) beamlines at the Korea Atomic Energy Research Institute (KAERI) has been characterized for sub-100-femtosecond-accuracy time-resolved diffraction experiments. The UED beamlines are designed to deliver electron bunches of 30 fs (rms) duration and 10 fs (rms) timing fluctuation with pumping laser pulses. We have two UED beamlines for solid and gas-phase samples. The energy of the electron beam is ~3 MeV and the bunch charge is more than 1 pC. We measured single-shot and multi-shot electron diffraction patterns of single-crystalline-silicon and poly-crystalline-gold films to confirm the electron beam quality. The temporal characteristics of the electron bunches are investigated by using laser-induced ponderomotive deflecting and spectral decoding of coherent transition radiation from the electron bunch by pumping IR pulse.  
slides icon Slides WEB02 [13.820 MB]  
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