Author: Okamoto, H.
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TUPMY017 Laser Driven Dielectric Accelerator in the Non-relativistic Energy Region 1585
 
  • K. Koyama, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • S. Kurimura
    NIMS, Ibaraki, Japan
  • H. Okamoto, S. Otsuki
    The University of Tokyo, Tokyo, Japan
  • M. Yoshida
    KEK, Ibaraki, Japan
  
  Laser-driven dielectric accelerator (LDA) is suitable for delivering a submicron-size ultra-short electron beam, which is useful for studying basic processes of the radiation effect in a biological cell. Both the oblique incidence and the normal incidence configurations of LDA were studied. The oblique incidence configuration of LDA relaxes the synchronization condition as ve=¥pm c LG/¥left(¥λ+ LG n ¥sin ¥theta ¥right) and is somewhat suitable for accelerating the non-relativistic electrons. The required energy to accelerate electrons in the oblique incidence configuration is smaller than that in the normal incidence configuration by a factor of ¥cos ¥theta, where ¥theta is the incidence angle of the laser beam. Two gratings each were made of different material structure of silica ({¥rm SiO2}) were fabricated by the electron beam lithography. When a crystal silica was adopted, many large humps of several hundred nm size were observed in grooves of the grating. On the other hand, a glass silica had smoother grooves.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY017  
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THPOW056 Fiber Laser Development for Dielectric Laser-driven Accelerator and Electron Beam Source 4070
SUPSS024   use link to see paper's listing under its alternate paper code  
 
  • H. Okamoto, S. Otsuki
    The University of Tokyo, Tokyo, Japan
  • K. Koyama, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • D. Satoh, T. Shibuya
    TIT, Tokyo, Japan
  • M. Yoshida
    KEK, Ibaraki, Japan
  
  Our group is aiming for developing a table-top electronμbeam source, whose beam size is micro-meter order so that we can irradiate just the nuclei of cells (1μm) and observe the behavior in real time. This beam source will be realized by dielectric laser-driven accelerators(DLAs), which is expected to produce acceleration gradients of ~GV/m. To drive these accelerators, ultra-short pulse laser has to be incident to the structure*. We chose Ytterbium (Yb) fiber laser for generating and amplifying ultra-short laser pulse, which has high quantum efficiency and can easily pumped by LD, and is proper to produce ultra-short pulses because of its wide-band oscillation. We succeeded in getting ultra-short pulse (central wavelength: {1030} nm, average output: 10 W, pulse duration: ~10 ps, reputation rate: 84 MHz) from Yb fiber laser system. Also in order to make electron bunch by photo cathode, we then converted the obtained IR laser to UV of 258 nm (4ω) using BBO and LBO crystals. We are planning to amplify the pulses by Yb:YAG in future, which has its amplification band in {1030} nm.
* K. Koyama el al., "Design Of Photonic Crystal Accelerator For Radiation Biology," IPAC'12 Proceedings (2014) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW056  
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