研究者詳細 - 中井　光男

論文 - 中井　光男

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Development of multichannel low-energy neutron spectrometer 査読

Y. Arikawa, T. Nagai, Y. Abe, S. Kojima, S. Sakata, H. Inoue, M. Utsugi, Y. Iwasa, T. Murata, N. Sarukura, M. Nakai, H. Shiraga, S. Fujioka, H. Azechi

REVIEW OF SCIENTIFIC INSTRUMENTS 85 ( 11 ) 2014年11月

A multichannel low-energy neutron spectrometer for down-scattered neutron (DSN) measurements in inertial confinement fusion (ICF) experiments has been developed. Our compact-size 256-channel lithium-glass-scintillator-based spectrometer has been implemented and tested in ICF experiments with the GEKKO XII laser. We have performed time calibration of the 256-channel analog-to-digital convertor system used for DSN measurements via X-ray pulse signals. We have clearly observed the DD-primary fusion neutron signal and have successfully studied the detector's impulse response. Our detector is soon to be implemented in future ICF experiments. (C) 2014 AIP Publishing LLC.

Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron bunch 査読

Sadaoki Kojima, Yasunobu Arikawa, Yasuhiko Nishimura, Hiromi Togawa, Zhe Zhang, Takahito Ikenouchi, Tetsuo Ozaki, Alessio Morace, Takahiro Nagai, Yuki Abe, Shouhei Sakata, Hiroaki Inoue, Masaru Utsugi, Mitsuo Nakai, Hiroaki Nishimura, Hiroyuki Shiraga, Ryukou Kato, Shinsuke Fujioka, Hiroshi Azechi

REVIEW OF SCIENTIFIC INSTRUMENTS 85 ( 11 ) 2014年11月

A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons' energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is +/- 0.5 MeV for 6.0 MeV electrons. (C) 2014 AIP Publishing LLC.

Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeV 査読

S. Sakata, Y. Arikawa, S. Kojima, T. Ikenouchi, T. Nagai, Y. Abe, H. Inoue, A. Morace, M. Utsugi, R. Kato, H. Nishimura, M. Nakai, H. Shiraga, S. Fujioka, H. Azechi

REVIEW OF SCIENTIFIC INSTRUMENTS 85 ( 11 ) 2014年11月

A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (N-e = 1.0 x 10(-6) C, E-e = 16 +/- 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%-70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Delta h nu/h nu) of about 15%. Quantum efficiency of this spectrometer was designed to be 10(-7), 10(-4), 10(-5), respectively, for 2-10, 11-15, and 15-25 MeV of photon energy ranges. (C) 2014 AIP Publishing LLC.

Development of x-ray radiography for high energy density physics 査読

A. Morace, L. Fedeli, D. Batani, S. Baton, F. N. Beg, S. Hulin, L. C. Jarrott, A. Margarit, M. Nakai, M. Nakatsutsumi, P. Nicolai, N. Piovella, M. S. Wei, X. Vaisseau, L. Volpe, J. J. Santos

PHYSICS OF PLASMAS 21 ( 10 ) 2014年10月

We describe an experiment performed at the LULI laser facility using an advanced radiographic technique that allowed obtaining 2D, spatially resolved images of a shocked buried-code-target. The technique is suitable for applications on Fast Ignition as well as Warm Dense Matter research. In our experiment, it allowed to show cone survival up to Mbar pressures and to measure the shock front velocity and the fluid velocity associated to the laser-generated shock. This allowed obtaining one point on the shock polar of porous carbon. (C) 2014 AIP Publishing LLC.

High intensity g-ray and neutron generation by ultra intense laser 査読

Yasunobu Arikawa, Masaru Utsugi, Alessio Morace, Takahiro Nagai, Sadaoki Kojima, Shohei Sakata, Hiroaki Inoue, Shigeki Tokita, Yoshiki Nakata, Junji Kawanaka, Takahisa Jitsuno, Nobuhiko Sarukura, Noriaki Miyanaga, Mitsuo Nakai, Hiroyuki Shiraga, Hiroaki Nishimura, Hiroshi Azechi

ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 248 2014年8月

Stabilization of radiation reaction with vacuum polarization 査読

Keita Seto, Sen Zhang, James Koga, Hideo Nagatomo, Mitsuo Nakai, Kunioki Mima

PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS ( 4 ) 2014年4月

From the development of the electron theory by H. A. Lorentz in 1906, many authors have tried to reformulate this model. P. A. M. Dirac derived the relativistic-classical electron model in 1938, which is now called the Lorentz-Abraham-Dirac model. But this model has the big difficulty of the runaway solution. Recently, this equation has become important for ultra-intense laser-electron (plasma) interactions. For simulations in this research field, it is desirable to stabilize this model of the radiation reaction. In this paper, we will discuss this ability for radiation reaction with the inclusion of vacuum polarization.

Development of compton X-ray spectrometer for fast ignition experiment 査読

Sadaoki Kojima, Yasunobu Arikawa, Takahito Ikenouchi, Takahiro Nagai, Yuki Abe, Shouhei Sakata, Hiroaki Inoue, Takuya Namimoto, Shinsuke Fujioka, Mitsuo Nakai, Hiroyuki Shiraga, Tetsuo Ozaki, Makoto R. Asakawa, Ryukou Kato, Hiroshi Azechi

Plasma and Fusion Research 9 ( 3 ) 2014年

In the context of Fast Ignition, the fast electron temperature is a key parameter to determine the laserto- fast electron energy conversion efficiency. Bremsstrahlung X-ray (γ-ray) emission represents an attractive alternative to measure this fundamental parameter. In this study, a single-shot high-energy γ-ray spectrometer with sensitivity ranging from 0.5MeV to 7MeV was developed, allowing to estimate the γ-ray spectrum in the fast ignition. © 2014 The Japan Society of Plasma Science and Nuclear Fusion Research.

Energy transportation by mev hot electrons in fast ignition plasma driven with LFEX PW laser 査読

Zhe Zhang, Hiroaki Nishimura, Shinsuke Fujioka, Yasunobu Arikawa, Mitsuo Nakai, Hideo Nagatomo, Hiroyuki Shiraga, Sadaoki Kojima, Alessio Morace, Noriaki Miyanaga, Junji Kawanaka, Yoshiki Nakata, Takahisa Jitsuno, Hiroshi Azechi, Tetsuo Ozaki, Hui Chen, Jaebum Park, Gerald Jackson Williams, Tomoyuki Johzaki, Atsushi Sunahara

Plasma and Fusion Research 9 2014年

Implosion and heating experiments with the scheme of fast ignition (FI) have been performed on Gekko-XII and LFEX laser platform at the Institute of Laser Engineering in Osaka University. A cone-guided CD-shell has been used as a base-line target for the fast ignition realization. The information about energy transfer from LFEX petawatt (PW) laser is quantitatively studied with an absolute Kα diagnostics and a fast electron trajectory simulation. The transfer efficiency (ηTE) is estimated for a planar interaction as a reference and for several types of guiding-cone. As a general trend, the guiding-cone enhanced the ηTE by a factor of 3 comparing with the planar case.

The development of the neutron detector for the fast ignition experiment by using LFEX and gekko XII facility 査読

Nagai T, Nakai M, Arikawa Y, Abe Y, Kojima S, Sakata S, Inoue H, Fujioka S, Shiraga H, Sarukura N, Norimatsu T, Azechi H

Plasma and Fusion Research 9 ( SPECIALISSUE.3 ) 2014年

The neutron imaging diagnostics and reconstructing technique for fast ignition 査読

Inoue H, Arikawa Y, Nozaki S, Fujioka S, Nagai T, Kojima S, Abe Y, Sakata S, Kinjo A, Nakai M, Shiraga H, Azechi H

Plasma and Fusion Research 9 ( SPECIALISSUE.3 ) 2014年

Present status of fast ignition realization experiment and inertial fusion energy development 査読

H. Azechi, K. Mima, S. Shiraga, S. Fujioka, H. Nagatomo, T. Johzaki, T. Jitsuno, M. Key, R. Kodama, M. Koga, K. Kondo, J. Kawanaka, N. Miyanaga, M. Murakami, K. Nagai, M. Nakai, H. Nakamura, T. Nakamura, T. Nakazato, Y. Nakao, K. Nishihara, H. Nishimura, T. Norimatsu, P. Norreys, T. Ozaki, J. Pasley, H. Sakagami, Y. Sakawa, N. Sarukura, K. Shigemori, T. Shimizu, A. Sunahara, T. Taguchi, K. Tanaka, K. Tsubakimoto, Y. Fujimoto, H. Homma, A. Iwamoto

NUCLEAR FUSION 53 ( 10 ) 2013年10月

One of the most advanced fast ignition programmes is the fast ignition realization experiment (FIREX). The goal of its first phase is to demonstrate ignition temperature of 5 keV, followed by the second phase to demonstrate ignition-and-burn. The second series experiment of FIREX-I, from late 2010 to early 2011, has demonstrated a high (>10%) coupling efficiency from laser to thermal energy of the compressed core, suggesting that the ignition temperature can be achieved at laser energy below 10 kJ. Further improvement of the coupling efficiency is expected by introducing laser-driven magnetic fields.

Efficient Generation and Collimation of Relativistic Electron Beams for Fast-Ignition Laser Fusion

S. Fujioka, H. Shiraga, Y. Arikawa, Y. Fujimoto, Y. Hironaka, T. Jitsuno, J. Kawanaka, K. Mima, N. Miyanaga, M. Murakami, H. Nagatomo, M. Nakai, Y. Nakata, K. Nishihara, H. Nishimura, T. Norimatsu, Y. Sakawa, N. Sarukura, K. Shigemori, T. Shimizu, K. Tsubakimoto, Z. Zhang, A. Sunahara, T. Johzaki, T. Taguchi, A. Iwamoto, T. Ozaki, T. Watanabe, H. Sakagami, H. Azechi

2013年9月

Luminescence properties of Nd3+ and Er3+ doped glasses in the VUV region 査読

Kohei Yamanoi, Takahiro Murata, Yasunobu Arikawa, Tomoharu Nakazato, Marilou Cadatal-Raduban, Toshihiko Shimizu, Nobuhiko Sarukura, Mitsuo Nakai, Takayoshi Norimatsu, Hiroaki Nishimura, Hiroshi Azechi, Shigeru Fujino, Hideki Yoshida, Akira Yoshikawa, Nakahiro Satoh, Hirofumi Kan

OPTICAL MATERIALS 35 ( 11 ) 1962 - 1964 2013年9月

We report the vacuum ultraviolet (VUV) spectroscopy of APLF + Nd and APLF + Er glass, with composition 20Al(PO3)(3)-80LiF + 1NdF(3) and + 1ErF(3) (in mol%). APLF + Nd and APLF + Er have a dominant fluorescence peak at 185 nm and 168 nm with decay times of 4.5 ns and 5.8 ns, respectively. Fluorescence from APLF + Nd is attributed to 4f(2)5d -> 4f(3) transitions in neodymium (Nd) while fluorescence from APLF + Er is due to spin allowed transition in erbium (Er). This is the first report of VUV fluorescence from rare earth ions doped in glass hosts, which could provide the basis for mass production of VUV emitting materials. Our results also suggest the potential of using APLF + Nd and APLF + Er as neutron scintillators during inertial confinement fusion. (C) 2012 Elsevier B.V. All rights reserved.

Quantitative measurement of hard X-ray spectra from laser-driven fast ignition plasma 査読

Z. Zhang, H. Nishimura, T. Namimoto, S. Fujioka, Y. Arikawa, H. Nagatomo, M. Nakai, T. Ozaki, M. Koga, T. Johzaki, A. Sunahara, H. Chen, J. Park, G. J. Williams, H. Shiraga, S. Kojima, M. Nishikino, T. Kawachi, H. Hosoda, Y. Okano, N. Miyanaga, J. Kawanaka, Y. Nakata, T. Jitsuno, H. Azechi

High Energy Density Physics 9 ( 3 ) 435 - 438 2013年9月

Absolute K. α line spectroscopy is proposed for studying laser-plasma interactions taking place in the Au cone-guided fast ignition targets. X-ray spectra ranging from 20 to 100keV were quantitatively measured with a Laue spectrometer composed of a cylindrically curved crystal and a filter-absorption method for Bremsstrahlung continuum emission. The absolute sensitivities of the Laue spectrometer systems were calibrated using pre-characterized laser-produced X-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an X-ray diffraction code. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer mechanism, is derived from this work. The absolute yield of Au and Ta K. α lines were measured in the fast ignition experimental campaign performed at Institute of Laser Engineering, Osaka University. Applying the hot electron spectrum information from electron spectrometer and scaling laws, the energy transfer efficiency from the incident LFEX, a kJ-class PW laser, to hot electrons was derived for the first time. © 2013 Elsevier B.V.

FIREX foam cryogenic target development: Residual void reduction and estimation with solid hydrogen refractive index measurements 査読

A. Iwamoto, T. Fujimura, M. Nakai, T. Norimatsu, H. Sakagami, H. Shiraga, H. Azechi

Nuclear Fusion 53 ( 8 ) 2013年8月

Voidless fuel solidification within a foam material is attempted for the development of a Fast Ignition Realization EXperiment (FIREX) target. A typical target consists of a foam shell with a thin solid fuel layer, a gold cone guide and a glass fill tube. The foam layer is formed with aggregations of tiny cells. The porous foam material has the advantage of forming a uniform layer in a liquid state by the effect of capillarity. Random liquid-solid transitions of fuel, however, would cause void spaces in each cell because of their different densities. To form a voidless solid fuel layer in the FIREX target, we propose a layering method, which includes the process of controlled solidification and simultaneous liquid fuel supply to the liquid/solid interface. Normal H 2 is used as a surrogate fuel for our experiments. By applying a resorcinol/formalin aerogel, which has been developed in the Institute of Laser Engineering, Osaka University, instead of a foam material, formation of a solid H2 layer with reduced void spaces is preliminarily demonstrated. Related solid H2 refractive indices are measured to estimate the void fraction. Eventually, its filling factor reaches ∼99%. Furthermore, the application of the proved method is numerically simulated on the FIREX target. The method is confirmed to be applicable in it with a cone guide heating technique. © 2013 IAEA, Vienna.

OPIC Conference on Laser and Accelerator Neutron Sources and Applications '13 (LANSA'13) 開催報告

西村博明, 有川安信, 中井光男

レーザー研究 41 ( 7 ) 540 - 542 2013年7月

Electronic States of Trivalent Praseodymium Ion Doped in 20Al(PO3)(3)-80LiF Glass 査読

Tsuboi Mizuki, Takeda Kohei, Nakazato Tomoharu, Kono Masahiro, Yamanoi Kohei, Cadatal-Raduban Marilou, Sakai Kohei, Nishi Ryosuke, Minami Yuki, Mui Viet Luong, Arikawa Yasunobu, Shimizu Toshihiko, Sarukurua Nobuhiko, Norimatsu Takayoshi, Nakai Mitsuo, Azechi Hiroshi, Murata Takahiro, Fujino Shigeru, Yoshida Hideki, Yoshikawa Akira, Sato Nakahiro, Kan Hirofumi, Kamata Kei

JAPANESE JOURNAL OF APPLIED PHYSICS 52 ( 6 ) 2013年6月

New insights into the laser produced electron-positron pairs 査読

Hui Chen, M. Nakai, Y. Sentoku, Y. Arikawa, H. Azechi, S. Fujioka, C. Keane, S. Kojima, W. Goldstein, B. R. Maddox, N. Miyanaga, T. Morita, T. Nagai, H. Nishimura, T. Ozaki, J. Park, Y. Sakawa, H. Takabe, G. Williams, Z. Zhang

NEW JOURNAL OF PHYSICS 15 2013年6月

We report new results from the intense laser target interaction experiment that produces relativistic electron-positron pairs. Laser to electron energy transfer, inferred using x-ray and neutron measurements, was found to be consistent with the measured positrons. To increase the number of positrons, one needs to deliver a greater number of relativistic electrons from the laser-plasma interaction to the high Z gold target. A large preplasma was found to have a negative impact for this purpose, while the laser could produce hotter electrons in such preplasma. The peak energy shift in the positron spectrum is confirmed as the post-acceleration in the sheath potential behind the target. The results were supported by a collisional one-dimensional particle-in-cell code. This experiment was performed using the high-power LFEX laser at the Institute of Laser Engineering at Osaka University using a suite of diagnostics measuring electrons, positrons, x-rays and neutrons from the laser-target interaction at the relativistic regime.

Pr or Ce-doped, fast-response and low-afterglow cross-section-enhanced scintillator with Li-6 for down-scattered neutron originated from laser fusion 査読

Kozue Watanabe, Yasunobu Arikawa, Kohei Yamanoi, Marilou Cadatal-Raduban, Takahiro Nagai, Masahiro Kouno, Kohei Sakai, Tomoharu Nazakato, Toshihiko Shimizu, Nobuhiko Sarukura, Mitsuo Nakai, Takayoshi Norimatsu, Hiroshi Azechi, Akira Yoshikawa, Takahiro Murata, Shigeru Fujino, Hideki Yoshida, Nobuhiko Izumi, Nakahiro Satoh, Hirofumi Kan

JOURNAL OF CRYSTAL GROWTH 362 288 - 290 2013年1月

We explore the potential of Pr- or Ce-doped 20Al(PO3)(3)-80LiF (APLF80+3Pr or +3Ce) scintillator to observe the lower edge of down-scattered neutron and discriminate fusion originated neutron from strong X-ray signals. APLF80+3Pr or +3Ce scintillator exhibits considerably fast decay profiles and negligible slow-decay components. Using these newly developed APLF80+3Pr or +3Ce scintillators, we have successfully observed fusion-originated neutron signal in the midst of strong X-ray-excited fluorescence in an integrated experiment using our 10 kJ class GEKKO XII Nd-glass laser system. A sophisticated neutron detection system using APLF80+3Pr or 3Ce will be used for the first fast ignition experiment. (C) 2011 Elsevier BY. All rights reserved.

Development of time-of-flight neutron detector with fast-decay and low-afterglow scintillator for fast ignition experiment 査読

T. Nagai, Y. Arikawa, H. Hosoda, Y. Ioka, A. Hasegawa, K. Wada, S. Takaoku, M. Takata, K. Noritake, Y. Minami, K. Watanabe, K. Yamanoi, H. Nakamura, T. Watari, M. Cadatal-Raduban, T. Shimizu, N. Sarukura, M. Nakai, T. Norimatsu, H. Azechi

IFSA 2011 - SEVENTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS 59 2013年

A fast-decay and low-afterglow liquid scintillator was developed for the fast ignition experiment at the Institute of Laser Engineering (ILE). The liquid scintillator was coupled to a gated photomultiplier (PMT), and the gating performance under high-intensity gamma-rays was experimentally checked. In 2010, a detector with a high detection efficiency of 10(-4) was developed and installed in this experiment. The neutron yield in the fast heating experiment was successfully measured using this detector.

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