Author: Kan, K.
Paper Title Page
MOPPP006 Inverse Cherenkov Radiation based on Smith-Purcell Effect 577
  • K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
    ISIR, Osaka, Japan
  • M. Hangyo
    ILE Osaka, Suita, Japan
  • R. Kuroda, H. Toyokawa
    AIST, Tsukuba, Ibaraki, Japan
  Inverse Cherenkov radiation based on Smith-Purcell effect using metamaterial was investigated. A metallic grating and picosecond electron bunch of 27 MeV beam energy from a thermionic DC gun and linac were used for the inverse radiation. The frequency spectra in terahertz (THz) range were measured by a Michelson interferometer experimentally. Peaks of discrete component in the spectra shifted continuously according to the radiation angles, e. g. discrete peak changing from 0.117 to 0.085 THz with radiation angle along the electron bunch from 102 to 134 degree (backward) using a 2-mm-period metallic grating. In this presentation, experiment using another electron bunch generated by a photocathode RF gun linac will be reported.  
MOPPP007 High-intensity Monochromatic Cherenkov Radiation in THz Range by Femtosecond Electron Bunches in Impurity-doped Semiconductor Tube 580
  • A. Ogata, K. Kan, T. Kondoh, K. Norizawa, J. Yang, Y. Yoshida
    ISIR, Osaka, Japan
  A novel method to generate high-power THz radiation is proposed and the preliminary experiments are conducted. If a beam with a bunch length on the order of 100 fs is injected into an electron–hole plasma of a semiconductor with a plasma frequency on the order of THz, THz wake fields are coherently generated. If the beam moves on the axis of a hollow tube covered by a metal, the frequency spectrum of the radiation is composed of discrete components. Monochromatic radiation is obtained by making only the lowest frequency component coherent. In the preliminary experiments using mm-sized dielectric tubes, the radiation spectra, which was driven by electron bunches of 200fs/27 MeV, were measured directly by a Michelson interferometer and bolometer. Peaks at frequencies of 0.09 and 0.14 THz of transverse magnetic (TM) modes, which corresponded to TM03 and TM04, were observed. The other higher modes, e. g. 0.36 (TM09) and 0.40 THz (TM010), were also observed successfully at a bunch charge of 15 pC, which decreased the electron bunch length.  
THPPR058 Pulse Radiolysis using Double-decker Femtosecond Electron Beam from a Photocathode RF Gun 4106
  • K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
    ISIR, Osaka, Japan
  Pulse radiolysis, which utilizes an electron bunch and a probe light (laser), is a powerful tool that can be used for an observation of ultrafast radiation-induced phenomena. The time resolution in pulse radiolysis depends on the electron bunch length, the probe-light width, and the timing jitter between the electron bunch and the probe light. In order to reduce the jitter, double-decker accelerator, in which separated laser was injected on a photocathode RF gun for a generation of synchronized double electron beams, was applied to pulse radiolysis. One electron beam was used as a pump source of a material, e. g. water, and another as a probe light at 800 nm wavelength with Cherenkov radiation.  
THPPR059 Progress of the Equivalent Velocity Spectroscopy Method for Femtosecond Pulse Radiolysis by Pulse Rotation and Pulse Compression 4109
  • T. Kondoh, K. Kan, K. Norizawa, A. Ogata, S. Tagawa, J. Yang, Y. Yoshida
    ISIR, Osaka, Japan
  • H. Kobayashi
    KEK, Ibaraki, Japan
  Femtosecond pulse radiolysis is developed for studies of electron beam induced ultra-fast reaction in matter. 98 fs electron pulse was generated by a photocathode RF gun LINAC with a magnetic bunch compressor. However for more fine time resolution, the Equivalent velocity spectroscopy (EVS) method is required to avoid degradation of time resolution caused by velocity difference between electron and analysing light in sample. In the EVS method, incident analysing light is oblique toward electron beam with an angle associated with refractive index of sample, and then, electron pulse is rotated toward the direction of travel to overlap with light pulse. In previous studies, pulse rotation had not been compatible with pulse compression. However, by oblique incident of light to the photocathode, pulse rotation was compatible with pulse compression, and the time resolution was improved by principle of the equivalent velocity spectroscopy.  
FRXBB01 Femtosecond Electron Guns for Ultrafast Electron Diffraction 4170
  • J. Yang, K. Kan, T. Kondoh, N. Naruse, K. Tanimura, Y. Yoshida
    ISIR, Osaka, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
  This talk should describe the development of electron guns for producing femtosecond electron pulses with low (<0.1 micron) emittance, for ultrafast electron diffraction. Comparisons should be made between the systems developed by groups in Asia, Europe and America, outlining any similarities and contrasts. The focus should be on the technology for generating, accelerating, and controlling the bunches, but some description of the science applications should also be included. Finally, prospects for future developments should be considered.  
slides icon Slides FRXBB01 [7.004 MB]