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Kimura, K.

Paper Title Page
THPLS041 Observation of Intense Terahertz Synchrotron Radiation produced by Laser Bunch Slicing at UVSOR-II 3377
 
  • M. Katoh, M. Hosaka, K. Kimura, A. Mochihashi, M. Shimada
    UVSOR, Okazaki
  • T. Hara
    RIKEN Spring-8 Harima, Hyogo
  • T. Takahashi
    KURRI, Osaka
  • Y. Takashima
    Nagoya University, Nagoya
 
  We have performed electron bunch slicing experiments using a femto-second high power pulse laser in the UVSOR-II electron storage ring. As the pulse laser system we have used a Ti:Sa laser whose wavelength is 800 nm, typical pulse duration is 100 fs, pulse repetition is 1 kHz and typical average power is 2W. The laser is operated in mode-locked condition and synchronized with the electron beam revolution. The laser pulse is injected into an undulator section and it goes along with the electron bunch. By adjusting the radiation wavelength of the undulator to the laser wavelength, the electron beam energy can be partially modulated in the electron bunch. We have observed THz synchrotron radiation (SR) light from a bending magnet that is downstream of the interaction region. The SR light contains extremely intense THz pulse radiation that is synchronized with the laser injection. The extremely high intensity strongly suggests that the THz pulses are coherent synchrotron radiation from the electron bunch with a hole because of the laser-beam interaction.  
THPLS042 Observation of THz Synchrotron Radiation Burst in UVSOR-II Electron Storage Ring 3380
 
  • A. Mochihashi, M. Hosaka, M. Katoh, K. Kimura, M. Shimada
    UVSOR, Okazaki
  • T. Takahashi
    KURRI, Osaka
  • Y. Takashima
    Nagoya University, Nagoya
 
  Very intense THz synchrotron radiation bursts have been observed in single-bunch operation in the UVSOR-II electron storage ring*. The observation was performed in an infrared beam line in UVSOR-II by using a liquid-He-cooled In-Sb hot-electron bolometer that has a good response time of several microseconds. Thanks both to the beam line and the detector, it is clearly observed that the intense bursts have typical macroscopic and microscopic temporal structure. Macroscopically, it is clearly observed that the bursts tend to be generated with quasi-periodic structure in which the period tends to depend on the beam intensity. From a microscopic point of view, each burst has also quasi-periodic structure in itself, and the period almost corresponds to the half value of the inverse of the synchrotron oscillation frequency. The peak intensity of the bursts was about 10000 times larger than that of ordinary synchrotron radiation in the same wavelength region. The extremely high intensity strongly suggests that the bursts are coherent synchrotron radiation, although the radiation wavelength was much shorter than the electron bunch length.

*Y. Takashima et al., Jpn. J. Appl. Phys. 44, No.35 (2005) L1131.