Guang-Hoon Kim

Korea Electrotechnology Research Institute-KERI, Tsau-liang-hai, Busan, South Korea

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Publications (7)5.95 Total impact

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    ABSTRACT: From 2001, the laser wakefield accelerator has been studied at the Center for Advanced Accelerator (CAA) of Korea Electrotechnology Research Institute (KERI). For this study, 2 TW, 700 fs Ti: sapphire and Nd: Glass hybrid type laser was installed and self-modulated laser wakefiled acceleration (SM-LWFA) has been tried as a first step. Recently, electron beam generation from SM-LWFA is successfully performed and its energy and charge are measured as 6 MeV and 2 nC, respectively. In this paper, we describe the experimental detail and present a characterization result of the generated electron beam.
    11/2004;
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    ABSTRACT: Characterizations of the high-density gas jets are performed for the laser–gas interaction. It is shown that the gas density profile can be obtained without the Abel inversion, when a Gaussian distribution is assumed. In addition, a rectangular nozzle is characterized for the long plasma generation. In this case, the Boltzmann distribution is introduced for the density profile and its result shows a good agreement with the experimental result.
    Review of Scientific Instruments 09/2004; 75(9):2865-2868. · 1.60 Impact Factor
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    ABSTRACT: High-energy ion generation from the interaction of an ultrashort intense laser pulse with an overdense plasma slab is studied with fully electromagnetic and relativistic particle-in-cell simulation. With a properly designed underdense preplasma, we observed that the forward ion acceleration from the front surface can be enhanced. The momentum distribution functions of the accelerated ions are investigated with respect to the laser pulse intensity and the preplasma profile.
    Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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    Guang-Hoon Kim, Hae June Lee, Jong-UK Kim, Hyyong Suk
    Journal of the Optical Society of America B 01/2003; 20(2):351-359. · 2.21 Impact Factor
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    ABSTRACT: Self-injection mechanisms in the self-modulated laser wakefield acceleration (SM-LWFA) are investigated. Two-dimensional (2D) particle-in-cell (PIC) simulations show that a significant amount of plasma electrons can be self-injected into the acceleration phase of a laser wakefield by a dynamic increase in the wake wavelength in the longitudinal direction. In this process, it is found that the wake wavelength increases due to the relativistic effect and this leads to a large amount of electron injection into the wakefields. In this paper, the injection phenomena are studied with 2D simulations and a brief explanation of the new self-injection mechanism is presented.
    Japanese Journal of Applied Physics 01/2003; 42:7091-7094. · 1.07 Impact Factor
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    ABSTRACT: When a laser pulse is located on a downward density gradient of a plasma wave, the frequency of the laser pulse is blue-shifted and the group velocity increases. This phenomenon is called photon acceleration[1]. The interaction length between the laser pulse and the density gradient can be extended significantly by using a wake field generated by a short laser pulse propagating through plasmas. In this study, we present simulation results of the photon acceleration by one- and two-dimensional electromagnetic particle-in-cell codes, 1D-XOOPIC and OSIRIS. More than 150 percent of frequency upshift was observed in the one-dimensional simulation, but much less in the two-dimensional simulation because of laser diffraction and transverse plasma motion. The saturation mechanisms and the effects of slippage, dispersion, diffraction, and pump depletion are discussed for parameter optimization. [1] S. C. Wilks, J. M. Dawson, W. B. Mori, T. Katsouleas, and M. E. Jones, Phys. Rev. Lett. 62, 2600 (1989).
    11/2002;
  • Jong-Uk Kim, Guang-Hoon Kim, Hyyong Suk
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    ABSTRACT: Two-dimensional slices of the cross-sectional distributions of fuel images in the combustion chamber were visualized quantitatively using a laser-induced exciplex fluorescence technique. A new exciplex visualization system consisting of 5% N,N-dimethylaniline (DMA)\cdot5%1,4,6-trimethylnaphthalene (TMN) in 90% isooctane (2,2,4-trimethylpentane) fuel was employed. In this method, the vapor phase was tagged by the monomer fluorescence while the liquid phase was tracked by the exciplex fluorescence with good spectral and spatial resolution. The 308 nm (XeCl) line of an excimer laser was used to excite the doped molecules in the fuel and the resulting fluorescence images were obtained with an intensified charge coupled device (ICCD) detector as a function of time. The results demonstrate that at the end of the compression stroke, the liquid fuel was almost vaporized and a dense stratified vapor phase charge developed near the two spark plugs.
    Japanese Journal of Applied Physics 01/2002; 41:895-900. · 1.07 Impact Factor