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Tsujii, R.

Paper Title Page
THPMN034 Manipulation of Electron Beam Generation with Modified Magnetic Circuit on Laser-wakefield Acceleration 2790
  • A. Yamazaki, T. Hosokai, K. Kinoshita, A. Maekawa, R. Tsujii, M. Uesaka, A. G. Zhidkov
    UTNL, Ibaraki
  Electron beam injection triggered by intense ultrashort laser pulses, which is called as plasma cathode, is presented. We have studied generation of relativistic electrons by interaction between a high intensity ultra-short laser pulse and gas jet. When a static magnetic field of 0.2 T is applied, the modification of the preplasma cavity, and significant enhancement of emittance and an increase of the total charge of electron beams produced by a 12 TW, 40 fs laser pulse tightly focused in a He gas jet, were observed. And very high stability and reproducibility of the characteristics and position of well-collimated electron beams was detected. Now we are planning to experiment with a magnetic circuit that has more intense magnetic field of 1 T. The present report aims at presenting these experimental and analytical results.  
FRPMN044 Measurement of Ultra-short Electron Bunch Duration by Coherent Radiation Analysis in Laser Plasma Catode 4066
  • R. Tsujii, K. Kinoshita, Y. Kondo, A. Maekawa, Y. Shibata, M. Uesaka, A. Yamazaki
    UTNL, Ibaraki
  • T. Hosokai
    RLNR, Tokyo
  • T. Takahashi
    KURRI, Osaka
  • A. G. Zhidkov
    Central Research Institute of Electric Power Industry, Komae
  Laser plasma accelerator can recently generate monochromatic and low-emittanced electron bunchs. Its pulse duration is femtoseconds, 40fs by the PIC simulation and about 250fs by measurement at University of Tokyo. But in such measurements only time-averaged spectrum and pulse duration were obtained by a few bolometers and coherent transition radiation (CTR) interferometer. Since the electron generation and acceleration are not stable yet, we need to know shot-by-shot behavior to improve its mechanism. Here we introduce the polychromator with ten channel-sensors for the single shot measurement. By this polychromator, we can obtain such a discrete spectrum of CTR by a single shot, thus the bunch duration can also be obtained shot-by-shot. This polychromator has ten channels to observe infrared radiation, and is mainly sensitive for the wavelengths around 1~2mm. We select this range of wavelength as the measurement tool, because the electron bunch duration changes shot-by-shot during traveling along the distance between the plasma and Ti foil (CTR emitter) due to their energy spectrum fluctuation. Further results and discussion will be presented on the spot.