Author: Nam, I.H.
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WEPMY014 Feasibility Study of a Laser-Driven High Energy Electron Acceleration in a Long Up-Ramp Density 2576
  • M. Kim, J. Kim, S.W. Lee, I.H. Nam, H. Suk
    GIST, Gwangju, Republic of Korea
  Laser-driven wakefield acceleration (LWFA) has received much attention as it can produce GeV-level high-energy electrons in cm-scale distance*. However, the accelerated electron energies are still limited by several factors, especially by the dephasing problem that is caused by different velocities between the plasma wake wave and the accelerated electron beam. In order to increase the acceleration length restricted by the dephasing problem**, we developed a gas-cell with density-tapering, which is realized by applying different gas pressures into two gas inlets in the gas cell. In this way, the gas density and gradient can be easily controlled in the gas cell. We used the density-tapered gas-cell for laser wakefield acceleration experiments in our laboratory with a 20 TW/40 fs Ti:sapphire laser system***. The results show that the electron energy can be significantly enhanced (about twice) with the tapered density gas-cell, compared with a uniform density conventional gas-cell. In this presentation, we show the experimental results and comparison with two-dimensional (2-D) particle-in-cell (PIC) simulation results.
* W. P. Leemans et al. Phy. Rev. Lett. 113, 245002 (2014).
** M. S. Kim et al. Appl. Phy. Lett. 102, 204103 (2013).
*** I. H. Nam et al. Curr. Appl. Phy. 15, 468 (2015).
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY014  
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WEPMY015 Numerical Studies on Tunable Coherent Radiations with a Laser-Plasma Accelerator 2579
  • J. Kim, M. Kim, I.H. Nam, H. Suk
    GIST, Gwangju, Republic of Korea
  • M.S. Hur
    UNIST, Ulsan, Republic of Korea
  Generation of tunable coherent radiation is numerically investigated via the two-dimensional particle-in-cell (2D-PIC) code developed by UNIST* and SIMPLEX developed by Spring-8. The electron beams can be produced by the laser-driven wakefield acceleration technique. The electron beam energy can be easily adjusted between 450 MeV and 800 MeV with a tapered density plasma on the order of 1×1018 cm-3 while the driving laser power is fixed, and the high-energy electron beams can be sent through the undulator arrays for the coherent light emission. The energy-controllable electron bunches can provide an opportunity to control the radiation wave-length with the fixed gap undulators. For the tapered density profile, a capillary cell with two gas inlets can be used. In this paper, we show some simulation and numerical research results regarding these issues, which reveal the possibility for a tunable light source in the soft X-ray regime.
* M. S. Hur, H. Suk, Phys. Plasmas 18 033102 (2011).
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY015  
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