Author: Sakai, T.
Paper Title Page
TUPAB116 Toward THz Coherent Undulator Radiation Experiment with a Combination of Velocity Bunchings 1663
 
  • Y. Sumitomo, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka
    LEBRA, Funabashi, Japan
  
  Funding: Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631.
We have launched a research program to generate the THz coherent undulator radiations, following the proposal of the combination of velocity bunchings * at Nihon University. The combination of velocity bunchings is an efficient way of bunch compression allowing a range of energy choices, in other words, a range of quasi-monochromatic radiation wavelengths generated at the undulator. In addition to the existing wideband THz light sources (0.1 - 2 THz) by the coherent edge and transition radiations currently available at Nihon Univ., the development of a high peak-power and quasi-monochromatic coherent radiation should accelerate the activities including the material science related to the THz bandwidths. In this presentation, we illustrate the program and report the current status of the experiment.
* Y. Sumitomo et al., J. Phys. Conf. Ser., vol. 1067, p. 032017, 2018. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB116  
About • paper received ※ 19 May 2021       paper accepted ※ 15 June 2021       issue date ※ 15 August 2021  
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WEPAB055 Development of a Linac for Injection of Ultrashort Electron Bunches Into Laser Plasma Electron Accelerators 2725
 
  • S. Masuda, N. Kumagai, T. Masuda, Y. Otake
    JASRI, Hyogo, Japan
  • Y. Koshiba, S. Otsuka
    Waseda University, Tokyo, Japan
  • T. Sakai, T. Tanaka
    LEBRA, Funabashi, Japan
  • K. Sakaue
    The University of Tokyo, The School of Engineering, Tokyo, Japan
  
  Funding: This work is supported by JST-Mirai Program Grant Number JPMJMI17A1, Japan.
We are developing a C-band linac that produces ultrashort electron bunches as an injector for laser plasma accelerators. A plasma wave excited by a high intense ultrashort laser pulse has a wavelength of the order of 10 to 100 fs and transverse dimensions of the order of 10 to 100 um. To inject the bunch into a proper phase of the plasma wave, a length and transverse sizes of the bunch must be much smaller than the plasma wave structure. A laser triggered photo cathode electron RF-gun and a 2pi/3 mode traveling wave buncher with 24 cells for ultrashort electron bunch production have been developed based on electron beam tracking simulations that show the bunch length is less than 10 fs with a charge of 100 fC at a focus on the plasma wave. The simulations also show that sufficiently small transverse sizes of the bunch at the focus can be obtained by a Q triplet. A highly accurate timing lower than the plasma wavelength (~10fs) is required for the synchronization between the electron bunch injection and the plasma wave excitation. An RF master oscillator with low SSB phase noise (-150dBc/Hz@10MHz) has been developed for the synchronization. We will report present development status. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB055  
About • paper received ※ 19 May 2021       paper accepted ※ 15 July 2021       issue date ※ 29 August 2021  
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WEPAB071 Design and Construction of an Intense Terahertz-Wave Source Based on Coherent Cherenkov Radiation Matched to Circle Plane Wave 2751
 
  • N. Sei, H. Ogawa
    AIST, Tsukuba, Ibaraki, Japan
  • K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, Y. Takahashi, T. Tanaka
    LEBRA, Funabashi, Japan
  • T. Takahashi
    Kyoto University, Research Reactor Institute, Osaka, Japan
  
  Funding: This work was supported by Japan Society for the Promotion of Science KAKENHI JP19H04406 and the Visiting Researchers Program of Kyoto University Research Reactor Institute (R2013).
National Institute of Advanced Industrial Science and Technology has been studied terahertz (THz) coherent radiation in collaboration with Nihon University and Kyoto University. We have been developed a coherent transition radiation (CTR) source with macropulse power of 1 mJ using a screen monitor in the parametric X-ray line at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. However, to obtain a THz-wave source with higher intensity, we have undertaken a development of a new THz-wave source based on coherent Cherenkov radiation (CCR) matched to circle plane wave. Bypassing an electron beam through a hollow conical dielectric having an apex angle equal to the Cherenkov angle, the wavefront of the CCR generated on the inner surface of the hollow conical dielectric matches on the basal plane. Therefore, it is possible to obtain a high-power beam that is easy to transport. We have already produced a hollow conical dielectric made of high-resistivity silicon and considered a position controller for the hollow conical dielectric. In this presentation, the status of the new THz-wave source will be reported. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB071  
About • paper received ※ 18 May 2021       paper accepted ※ 22 June 2021       issue date ※ 21 August 2021  
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