Y. Nodera

Utsunomiya University, Tochigi, Tochigi-ken, Japan

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Publications (11)4.05 Total impact

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    ABSTRACT: In a laser-foil interaction, a subwavelength-scale-multihole thin-foil target is proposed to increase the energy-conversion efficiency from laser to protons. The multiholes transpiercing the foil target enhance the laser-proton energy-conversion efficiency significantly.
    08/2009;
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    ABSTRACT: In a proton beam generation by a laser-foil interaction, significant improvement of energy-conversion efficiency from laser to proton beam is presented by particle simulations. When an intense short-pulse laser illuminates the thin-foil target, the foil electrons are accelerated around the target by the ponderomotive force. The hot electrons generate a strong electric field, which accelerates the foil protons, and the proton beam is generated. In this paper, a tailored multihole thin-foil target is proposed in order to increase the energy-conversion efficiency from laser to protons. The multiholes transpiercing the foil target enhance the laser-proton energy-conversion efficiency significantly. Particle-in-cell 2.5-dimensional simulations present that the total laser-proton energy-conversion efficiency becomes 9.3% for the tailored multihole target, although the energy-conversion efficiency is 1.5% for a plain thin-foil target. The maximum proton energy is 10.0 MeV for the multihole target and is 3.14 MeV for the plain target. The transpiercing multihole target serves a new method to increase the energy-conversion efficiency from laser to ions.
    IEEE Transactions on Plasma Science 05/2009; · 0.87 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Improvement of energy conversion efficiency from laser to proton beam is demonstrated by particle simulations in a laser- foil interaction. When an intense short-pulse laser illuminates the thin foil target, the foil electrons are accelerated around the target by the ponderomotive force. The hot electrons generate a strong electric field, which accelerates the foil protons, and the proton beam is generated. In this paper a multihole thin- foil target is proposed in order to increase the energy conversion efficiency from laser to protons. The multiholes transpiercing the foil target help to enhance the laser-proton energy conversion efficiency significantly. 2.5-dimensional particle-in-cell simulations present that the total laser- proton energy conversion efficiency becomes 9.3% for the multihole target, though the energy con version efficiency is 1.5% for a plain thin foil target. The maximum proton energy is lO.OMeV for the multihole target and is 3.14MeV for the plain target. The transpiercing multihole target serves a new method to increase the energy conversion efficiency from laser to ions. One of problems in the laser-ion acceleration is the energy conversion efficiency from laser to ions, and the energy conversion efficiency is low in actual experiments. The sub- wavelength fine microstructure enhances the laser energy absorption and the ion beam generation.
    IEEE International Conference on Plasma Science 01/2009;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Improvement of energy-conversion efficiency from laser to proton beam is demonstrated by particle simulations in a laser-foil interaction. When an intense short-pulse laser illuminates the thin-foil target, the foil electrons are accelerated around the target by the ponderomotive force. The hot electrons generate a strong electric field, which accelerates the foil protons, and the proton beam is generated. In this paper a multihole thin-foil target is proposed in order to increase the energy-conversion efficiency from laser to protons. The multiholes transpiercing the foil target help to enhance the laser-proton energy-conversion efficiency significantly. Particle-in-cell 2.5-dimensional ( x, y, vx, vy, vz) simulations present that the total laser-proton energy-conversion efficiency becomes 9.3% for the multihole target, though the energy-conversion efficiency is 1.5% for a plain thin-foil target. The maximum proton energy is 10.0 MeV for the multihole target and is 3.14 MeV for the plain target. The transpiercing multihole target serves as a new method to increase the energy-conversion efficiency from laser to ions.
    Physical Review E 11/2008; 78(4 Pt 2):046401. · 2.31 Impact Factor
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    ABSTRACT: Divergence suppression of laser-produced proton beam is demonstrated by a tailored thin-foil target with hole. When an intense short-pulse laser illuminates the thin-foil target with the hole, transverse-edge effects of an accelerated electron cloud and an ion source cloud are eliminated by a protuberant part of the hole. The edge fields of the electron cloud and the ion source cloud induce the proton-beam divergence. Therefore, the transverse proton-beam divergence is suppressed by the tailored hole target. First, this paper presents the robustness of the hole target against a contaminated proton-source layer. It may be also difficult to make the laser axis coincide with the target-hole center line in realistic experiments and uses when the target has only one hole. The 2.5-D particle-in-cell simulations present that a multiple-hole target is robust against the laser-alignment and the target-setting errors. The multiple-hole target may serve as a robust target for practical uses to produce a collimated proton beam. In addition, a method for a proton-energy-spectrum control is also proposed by using a hole-cover layer. The hole-cover layer serves a role of high-energy proton selection.
    IEEE Transactions on Plasma Science 05/2008; · 0.87 Impact Factor
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    ABSTRACT: In a laser-foil interaction for an ion beam generation, suppression of a transverse proton beam divergence is realized by a tailored thin foil target, which has holes at the rear side of the target. The electron and proton clouds are limited in transverse by the plasma at the protuberant part. In this paper, we investigate the robustness of the hole target for the high quality proton beam generation in the laser-plasma interaction. The transverse edge effects of the ion cloud and the electron cloud deform the potential shape, which defines the proton extraction direction. Consequently the proton beam divergence is induced by the deformed potential shape. The protuberant part of the hole target shields the edge fields of the ion and electron clouds. The present work demonstrate that the hole target is robust against the additional contaminated proton source layers. The multiple-hole target is also robust against the laser alignment error and the target positioning error. The multiple-hole target may serve a robust target to produce a collimated proton beam in realistic experiments and uses.
    Journal of Physics Conference Series 01/2008; 112(4).
  • International Congress on Plasma Physics 2008(ICPP2008), Fukuoka International Congress Center, Fukuoka, Japan, (8-12 Sep., 2008); 01/2008
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    ABSTRACT: A thin-foil tailored hole target is proposed for an efficient production of a collimated proton beam in a laser target interaction. The tailored target has holes at the target surface. When an intense short pulse laser illuminates the thin foil hole target, transverse edge fields of an accelerated electron cloud and a proton source cloud are shielded by a protuberant part of the hole so that the proton beam divergence is suppressed. This paper presents a robustness of the hole target against laser parameter changes, against a contaminant proton source layer and against a laser alignment error. The 2.5-dimensional PIC (particle-in-cell) simulations also present that a multiple-hole target serves a high energy efficiency of the proton beam generation. Recent researches in this field have demonstrated acceleration of ions to a high energy in an interaction between an intense laser pulse and a thin foil target. The ion beams are expected to be useful for basic particle physics, medical therapy, controlled nuclear fusion, high-energy sources and so on. The important issues of the ion beam production include a quality of the ion beam and an efficient energy convergence to the ion beam from the laser. This paper presents a new method for the efficient collimated proton beam in the laser foil interaction.
    IEEE International Conference on Plasma Science 01/2008;
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    ABSTRACT: A high-quality collimated proton beam generation is demonstrated by using a tailored thin foil target. A robustness of a thin-foil tailored hole target is demonstrated by particle simulations in laser-produced proton generation. The tailored target has holes at the target rear surface. When an intense short pulse laser illuminates the thin foil target with the hole, transverse edge fields of an accelerated electron cloud and an ion cloud are shielded by a protuberant part of the hole so that the proton beam divergence is suppressed [1, 2]. This paper presents the robustness of the hole target against laser parameter changes in a laser spot size and in a laser pulse length, against a contaminated proton source layer and against a laser alignment error. The 2.5-dimensional PIC (particle-in-cell) simulations also present that a multiple-hole target is robust against a laser alignment error and a target positioning error. The multi-hole target may serve a robust target for practical uses to produce a collimated proton beam. [1] R. Sonobe, et al., Phys. Plasmas, 12 (2005) 073104. [2] M. Nakamura, et al., J. Appl. Phys., 101 (2007) 113305.
    11/2007;
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    ABSTRACT: Suppression effect of proton beam divergence is numerically demonstrated in a tailored thin foil target with a hole at the opposite side of laser illumination. When an intense short pulse laser illuminates the thin foil target with the hole, edge effects of an accelerated electron cloud and an ion source cloud are eliminated by a protuberant part of the hole: the edge effects of the electron and ion-source clouds induce the proton beam divergence. Therefore the transverse proton beam divergence was suppressed well. In this study, we present the robustness of the hole target against laser parameter changes in a laser spot size and a laser pulse length, against a contaminated proton source layers, the laser alignment error, and the target positioning error by using particle-in-cell simulations.
    Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
  • Fifth International Conference on Inertial Fusion Sciences and Applications, Kobe, Japan, (9-14 September, 2007); 01/2007