Electron Accelerators and Applications
Synchrotron light sources
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MOPO073 Coherent Edge Radiation Sources in Linac-Based Infrared Free-Electron Laser Facilities 154
  • N. Sei, H. Ogawa
    AIST, Tsukuba, Ibaraki, Japan
  • K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, T. Tanaka
    LEBRA, Funabashi, Japan
  • H. Ohgaki, H. Zen
    Kyoto University, Kyoto, Japan
  Funding: This study was financially supported by JSPS KAKENHI Grant Number JP16H03912.
National Institute of Advanced Industrial Science and Technology has been studied far-infrared coherent radiation at Linac-based infrared free-electron laser (FEL) facilities in col-laboration with Nihon University and Kyoto University. To obtain high FEL gain at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University and at Kyoto Uni-versity Free Electron Laser (KU-FEL), the electron-bunch length is compressed to less than 1 ps in their undulator sections. Short electron bunches are suitable for generating intense coher-ent radiation, and we have already developed some terahertz-wave sources based on the coher-ent synchrotron radiation and the coherent transition radiation [1-3]. However, it was difficult to observe them with sufficient intensity without disturbing the infrared FEL oscillations. Then, we now develop coherent edge radiation emitted from downstream bending magnets in the un-dulator sections. It can be extracted from the undulator sections without disturbing the FEL os-cillations. In this presentation, the observed coherent radiation at LEBRA and KU-FEL will be reported on.
[1] N. Sei et al., J. Phys. D: Appl. Phys. 46, (2013) 045104.
[2] N. Sei et al., Nucl. Instr. and Meth. A, 832, (2016) 208.
[3] N. Sei et al., Jpn. J. Appl. Phys.: 56, (2017) 032401.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO073  
About • paper received ※ 29 August 2018      issue date ※ 18 January 2019  
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MOPO076 Study on Generation of Variable Polarized Coherent THz Radiation Using a Crossed Undulator 157
SPWR004   use link to see paper's listing under its alternate paper code  
  • H. Saito, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, T. Muto, I. Nagasawa, K. Nanbu, S. Ninomiya, K. Takahashi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  A variable polarized THz radiation source using a crossed undulator system has been developed at Tohoku University. In this scheme, two coherent undulator radiations from an extremely short electron bunch are used to control the polarization. They are linearly polarized radiations orthogonal to each other. Polarization of superimposed radiation is controlled by adjusting a relative phase between them. A compact planar undulator with seven periods has been designed for an experiment at our facility. The radiation frequency is 2.06 THz for electron beam energy of 22 MeV. The opening angle of the crossed undulator radiation was estimated to be 34 mrad (FWHM). Since the polarization state of the crossed undulator depends on observation angle, its angular dependence was evaluated. It was found that ideal polarization control is realized only in the angle range of 2.5 mrad, which is quite smaller than that of the radiation itself.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO076  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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