研究者詳細 - 中井　光男

論文 - 中井　光男

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Implosion and heating experiments of fast ignition targets by Gekko-XII and LFEX lasers 査読

H. Shiraga, S. Fujioka, M. Nakai, T. Watari, H. Nakamura, Y. Arikawa, H. Hosoda, T. Nagai, M. Koga, H. Kikuchi, Y. Ishii, T. Sogo, K. Shigemori, H. Nishimura, Z. Zhang, M. Tanabe, S. Ohira, Y. Fujii, T. Namimoto, Y. Sakawa, O. Maegawa, T. Ozaki, K. A. Tanaka, H. Habara, T. Iwawaki, K. Shimada, M. Key, P. Norreys, J. Pasley, H. Nagatomo, T. Johzaki, A. Sunahara, M. Murakami, H. Sakagami, T. Taguchi, T. Norimatsu, H. Homma, Y. Fujimoto, A. Iwamoto, N. Miyanaga, J. Kawanaka, T. Kanabe, T. Jitsuno, Y. Nakata, K. Tsubakimoto, K. Sueda, R. Kodama, K. Kondo, N. Morio, S. Matsuo, T. Kawasaki, K. Sawai, K. Tsuji, H. Murakami, N. Sarukura, T. Shimizu, K. Mima, H. Azechi

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

The FIREX-1 project, the goal of which is to demonstrate fuel heating up to 5 keV by fast ignition scheme, has been carried out since 2003 including construction and tuning of LFEX laser and integrated experiments. Implosion and heating experiment of Fast Ignition targets have been performed since 2009 with Gekko-XII and LFEX lasers. A deuterated polystyrene shell target was imploded with the 0.53-mu m Gekko-XII, and the 1.053-mu m beam of the LFEX laser was injected through a gold cone attached to the shell to generate hot electrons to heat the imploded fuel plasma. Pulse contrast ratio of the LFEX beam was significantly improved. Also a variety of plasma diagnostic instruments were developed to be compatible with harsh environment of intense hard x-rays (gamma rays) and electromagnetic pulses due to the intense LFEX beam on the target. Large background signals around the DD neutron signal in time-of-flight record of neutron detector were found to consist of neutrons via (gamma, n) reactions and scattered gamma rays. Enhanced neutron yield was confirmed by carefully eliminating such backgrounds. Neutron enhancement up to 3.5 x 10(7) was observed. Heating efficiency was estimated to be 10-20% assuming a uniform temperature rise model.

Implosion and heating experiments of fast ignition targets by Gekko-XII and LFEX lasers 査読

EPJ Web of Conferences 59 2013年

The FIREX-1 project, the goal of which is to demonstrate fuel heating up to 5 keV by fast ignition scheme, has been carried out since 2003 including construction and tuning of LFEX laser and integrated experiments. Implosion and heating experiment of Fast Ignition targets have been performed since 2009 with Gekko-XII and LFEX lasers. A deuterated polystyrene shell target was imploded with the 0.53- μm Gekko-XII, and the 1.053- μm beam of the LFEX laser was injected through a gold cone attached to the shell to generate hot electrons to heat the imploded fuel plasma. Pulse contrast ratio of the LFEX beam was significantly improved. Also a variety of plasma diagnostic instruments were developed to be compatible with harsh environment of intense hard x-rays (γ rays) and electromagnetic pulses due to the intense LFEX beam on the target. Large background signals around the DD neutron signal in time-of-flight record of neutron detector were found to consist of neutrons via (γ,n) reactions and scattered gamma rays. Enhanced neutron yield was confirmed by carefully eliminating such backgrounds. Neutron enhancement up to 3.5 × 107 was observed. Heating efficiency was estimated to be 10-20% assuming a uniform temperature rise model. © Owned by the authors, published by EDP Sciences, 2013.

Multichannel down-scattered neutron detector for areal density measurement

Y. Arikawa, H. Hosoda, T. Nagai, K. Watanabe, K. Yamanoi, M. Cadatal-Raduban, T. Shimizu, N. Sarukura, M. Nakai, T. Norimatsu, H. Azechi, N. Izumi, T. Murata, T. Suyama, A. Yoshikawa, K. Kamada, Y. Usuki, N. Satoh, H. Kan

EPJ Web of Conferences 59 UNSP 13011 2013年

A down-scattered neutron detector operating in the multichannel counting mode was developed for areal density (ρR) measurement. Equipped with a newly developed 6Li glass scintillator (APLF80), the detector was tested in a fusion experiment at the GEKKO XII facility, Osaka University, Osaka, Japan. For a low-ρR fusion shot, the detector clearly discriminated the γ-rays, primary neutrons, γ-rays produced via (n, γ) reactions from the target chamber, and neutrons scattered by the target chamber. Furthermore, the observed signal was in good agreement with predictions made by Monte Carlo simulation. © Owned by the authors, published by EDP Sciences, 2013.

Recent progress of fuel layering study for FIREX cryogenic target 査読

A. Iwamoto, T. Fujimura, M. Nakai, T. Norimatsu, H. Shiraga, H. Azechi, Y. Fujimoto, S. Machi, H. Sakagami

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

Fast-Response and Low-Afterglow Cerium-Doped Lithium 6 Fluoro-Oxide Glass Scintillator for Laser Fusion-Originated Down-Scattered Neutron Detection 査読

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

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 59 ( 5 ) 2256 - 2259 2012年10月

The photonuclear neutron and gamma-ray backgrounds in the fast ignition experiment 査読

Y. Arikawa, T. Nagai, H. Hosoda, Y. Abe, S. Kojima, S. Fujioka, N. Sarukura, M. Nakai, H. Shiraga, T. Ozaki, H. Azechi

Review of Scientific Instruments 83 ( 10 ) 10D909 2012年10月

In the fast-ignition scheme, very hard x-rays (hereinafter referred to as γ-rays) are generated by Bremsstrahlung radiation from fast electrons. Significant backgrounds were observed around the deuterium-deuterium fusion neutron signals in the experiment in 2010. In this paper the backgrounds were studied in detail, based on Monte Carlo simulations, and they were confirmed to be γ-rays from the target, scattered γ-rays from the experimental bay walls γ'-rays), and neutrons generated by (γ, n) reactions in either the target vacuum chamber or the diagnostic instruments (γ-n neutrons). © 2012 American Institute of Physics.

Integrated experiments of fast ignition targets by Gekko-XII and LFEX lasers 査読

H. Shiraga, S. Fujioka, M. Nakai, T. Watari, H. Nakamura, Y. Arikawa, H. Hosoda, T. Nagai, M. Koga, H. Kikuchi, Y. Ishii, T. Sogo, K. Shigemori, H. Nishimura, Z. Zhang, M. Tanabe, S. Ohira, Y. Fuji, T. Namimoto, Y. Sakawa, O. Maegawa, T. Ozaki, K. A. Tanaka, H. Habara, T. Iwawaki, K. Shimada, H. Nagatomo, T. Johzaki, A. Sunahara, M. Murakami, H. Sakagami, T. Taguchi, T. Norimatsu, H. Homma, Y. Fujimoto, A. Iwamoto, N. Miyanaga, J. Kawanaka, T. Jitsuno, Y. Nakata, K. Tsubakimoto, K. Sueda, N. Morio, S. Matsuo, T. Kawasaki, K. Sawai, K. Tsuji, H. Murakami, T. Kanabe, K. Kondo, R. Kodama, N. Sarukura, T. Shimizu, K. Mima, H. Azechi

HIGH ENERGY DENSITY PHYSICS 8 ( 3 ) 227 - 230 2012年9月

Implosion and heating experiments at the Institute of Laser Engineering, Osaka University on Fast Ignition (FI) targets for the FIREX-1 project have been performed with Gekko-XII laser for implosions and LFEX laser for heating. We tried to reduce the prepulse level in the LFEX laser system and have improved the plasma diagnostics to observe the plasma in the harsh hard X-ray envilonment. A plastic (CD) shell target, 7-mu m thick and 500 mu m in diameter with a hollow gold cone was used in this experiment to guide the short-pulse laser at the time of the maximum compression. The shell target was imploded with 9 or 12 beams of Gekko-XII laser (527 nm) with energy of 300 J/beam in a 1.5 ns pulse. Two of the four LFEX laser (1053 nm) beams were injected into the inside bottom of the cone with an energy up to 0.7 kJ/beam in a 1.5 Ps pulse at the time around the maximum implosion. We have observed neutron enhancement up to 3.5 x 10(7) with total heating energy of 300 J, which is higher than the yield obtained in the previous experiment in 2002 [R. Kodama et al. Nature 418,933 (2002)]. We found the estimated heating efficiency is at a level of 10-20%. Fuel heating to 5 keV is expected when the full output of LFEX is used. (c) 2012 Elsevier B.V. All rights reserved.

Fast ignition integrated experiments with Gekko and LFEX lasers 査読

H. Shiraga, S. Fujioka, M. Nakai, T. Watari, H. Nakamura, Y. Arikawa, H. Hosoda, T. Nagai, M. Koga, H. Kikuchi, Y. Ishii, T. Sogo, K. Shigemori, H. Nishimura, Z. Zhang, M. Tanabe, S. Ohira, Y. Fujii, T. Namimoto, Y. Sakawa, O. Maegawa, T. Ozaki, K. Tanaka, H. Habara, T. Iwawaki, K. Shimada, H. Nagatomo, T. Johzaki, A. Sunahara, M. Murakami, H. Sakagami, T. Taguchi, T. Norimatsu, H. Homma, Y. Fujimoto, A. Iwamoto, N. Miyanaga, J. Kawanaka, T. Jitsuno, Y. Nakata, K. Tsubakimoto, N. Morio, T. Kawasaki, K. Sawai, K. Tsuji, H. Murakami, T. Kanabe, K. Kondo, N. Sarukura, T. Shimizu, K. Mima, H. Azechi

PLASMA PHYSICS AND CONTROLLED FUSION 53 ( 12 ) 2011年12月

Based on the successful result of fast heating of a shell target with a cone for heating beam injection at Osaka University in 2002 using the PW laser (Kodama et al 2002 Nature 418 933), the FIREX-1 project was started in 2004. Its goal is to demonstrate fuel heating up to 5 keV using an upgraded heating laser beam. For this purpose, the LFEX laser, which can deliver an energy up to 10 kJ in a 0.5-20 ps pulse at its full spec, has been constructed in addition to the Gekko-XII laser system at the Institute of Laser Engineering, Osaka University. It has been activated and became operational since 2009. Following the previous experiment with the PW laser, upgraded integrated experiments of fast ignition have been started using the LFEX laser with an energy up to 1 kJ in 2009 and 2 kJ in 2010 in a 1-5 ps 1.053 mu m pulse. Experimental results including implosion of the shell target by Gekko-XII, heating of the imploded fuel core by LFEX laser injection, and increase of the neutron yield due to fast heating compared with no heating have been achieved. Results in the 2009 experiment indicated that the heating efficiency was 3-5%, much lower than the 20-30% expected from the previous 2002 data. It was attributed to the very hot electrons generated in a long scale length plasma in the cone preformed with a prepulse in the LFEX beam. The prepulse level was significantly reduced in the 2010 experiment to improve the heating efficiency. Also we have improved the plasma diagnostics significantly which enabled us to observe the plasma even in the hard x-ray harsh environment. In the 2010 experiment, we have observed neutron enhancement up to 3.5 x 10(7) with total heating energy of 300 J on the target, which is higher than the yield obtained in the 2009 experiment and the previous data in 2002. We found the estimated heating efficiency to be at a level of 10-20%. 5 keV heating is expected at the full output of the LFEX laser by controlling the heating efficiency.

LEAKAGE CONTROL OF TRITIUM THROUGH HEAT CYCLES OF CONCEPTUAL-DESIGN, LASER-FUSION REACTOR KOYO-F 査読

T. Norimatsu, H. Saika, H. Homma, M. Nakai, S. Fukada, A. Sagara, H. Azechi

FUSION SCIENCE AND TECHNOLOGY 60 ( 3 ) 893 - 896 2011年10月

To reduce the tritium permeation from the primary liquid metal loop to the secondary water loop, a heat exchanger concept that incorporates small diameter tubes containing an oxidizer was proposed. An inert gas containing a small amount of oxidizer flows in the small tubes oxiding tritium that comes from the primary liquid metal coolant. The tritiated water is sent to a tritium recovery system minimizing leakage to the secondary water loop. Our evaluation results indicated that the tritium leakage through the heat exchanger was reduced to 1/10(5) with an acceptable increase in the size of the heat exchanger.

Present states and future prospect of fast ignition realization experiment (FIREX) with Gekko and LFEX Lasers at ILE 査読

Mayuko Koga, Y. Arikawa, H. Azechi, Y. Fujimoto, S. Fujioka, H. Habara, Y. Hironaka, H. Homma, H. Hosoda, T. Jitsuno, T. Johzaki, J. Kawanaka, R. Kodama, K. Mima, N. Miyanaga, M. Murakami, H. Nagatomo, M. Nakai, Y. Nakata, H. Nakamura, H. Nishimura, T. Norimatsu, Y. Sakawa, N. Sarukura, K. Shigemori, H. Shiraga, T. Shimizu, H. Takabe, M. Tanabe, K. A. Tanaka, T. Tanimoto, T. Tsubakimoto, T. Watari, A. Sunahara, M. Isobe, A. Iwamoto, T. Mito, O. Motojima, T. Ozaki, H. Sakagami, T. Taguchi, Y. Nakao, H. Cai, M. Key, P. Norreys, J. Pasley

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 653 ( 1 ) 84 - 88 2011年10月

The fast ignition realization experiment (FIREX) project is progressing. The new short pulse laser system, LFEX laser, has been completely assembled and one of the four beamlets is now in operation. A fast-ignition experiment was performed using this single short pulse combined with the Gekko XII implosion laser. The energy of the GXII implosion laser was about 2 kJ and the pulse width was 1.5 ns. The energy of the LFEX laser was increased upto 800 J and two pulse durations 5 and 1.6 ps were compared. Targets were deuterated plastic shells with gold cones. It was found that the neutron yield was increased by a factor of 30 as a result of the fast electron-induced heating in LFEX 1.6 ps shot. The estimated coupling efficiency between the LFEX laser pulse and the compressed fuel was low (less than 5%). This may be due to pre-plasma formed by light arriving at the target before the main laser pulse. Further investigations and attempts to overcome these problems are now in progress. (C) 2011 Elsevier B.V. All rights reserved.

Fast-response, Low-Afterglow 4,4 '''-Bis[(2-butyloctyl)oxy]-1,1 ':4 ',1 '':4 '',1 '''-quarterphenyl Dye-Based Liquid Scintillator for High-Contrast Detection of Laser Fusion-Generated Neutrons 査読

Takahiro Nagai, Yusuke Ioka, Ai Hasegawa, Kazuhiro Wada, Shingo Takaoku, Masatoshi Takata, Katsuya Noritake, Yuki Minami, Kozue Watanabe, Kohei Yamanoi, Yasunobu Arikawa, Hirokazu Hosoda, Hirotaka Nakamura, Takeshi Watari, Marilou Cadatal-Raduban, Mayuko Koga, Toshihiko Shimizu, Nobuhiko Sarukura, Hiroyuki Shiraga, Mitsuo Nakai, Takayoshi Norimatsu, Hiroshi Azechi

JAPANESE JOURNAL OF APPLIED PHYSICS 50 ( 8 ) 2011年8月

4,4'''-Bis[(2-butyloctyl)oxy]-1,1':4',1 '':4 '',1'''-quaterphenyl (BBQ) dye dissolved in xylene and enriched with oxygen is shown to exhibit the characteristics of an ideal neutron scintillator for time-of-flight (TOF) measurement in a laser fusion experiment. Initial results from excitation with 290-nm pulses show that it has a 0.76-ns fast decay component and a negligible slow decay component or afterglow. By using this scintillator for TOF measurement, we have successfully discriminated between nuclear fusion-generated neutrons and X-rays. This would dramatically improve neutron diagnostics in fast ignition experiments where neutrons have to be detected in the presence of an intense X-ray burst. (C) 2011 The Japan Society of Applied Physics

Laser-shock compression and Hugoniot measurements of liquid hydrogen to 55 GPa 査読

T. Sano, N. Ozaki, T. Sakaiya, K. Shigemori, M. Ikoma, T. Kimura, K. Miyanishi, T. Endo, A. Shiroshita, H. Takahashi, T. Jitsui, Y. Hori, Y. Hironaka, A. Iwamoto, T. Kadono, M. Nakai, T. Okuchi, K. Otani, K. Shimizu, T. Kondo, R. Kodama, K. Mima

PHYSICAL REVIEW B 83 ( 5 ) 2011年2月

The principal Hugoniot for liquid hydrogen was obtained up to 55 GPa under laser-driven shock loading. The pressure and density of compressed hydrogen were determined by impedance matching to a quartz standard. The shock temperature was independently measured from the brightness of the shock front. Hugoniot data of hydrogen provide a good benchmark to modern theories of condensed matter. The initial number density of liquid hydrogen is lower than that for liquid deuterium, and this results in shock-compressed hydrogen having a higher compression and higher temperature than deuterium at the same shock pressure.

Optical and scintillation properties of Pr-doped Li-glass for neutron detection in inertial confinement fusion process 査読

Akihiro Fukabori, Takayuki Yanagida, Valery Chani, Federico Moretti, Jan Pejchal, Yuui Yokota, Noriaki Kawaguchi, Kei Kamada, Ken-ichi Watanabe, Takahiro Murata, Yasunobu Arikawa, Kohei Yamanoi, Toshihiko Shimizu, Nobuhiko Sarukura, Mitsuo Nakai, Takayoshi Norimatsu, Hiroshi Azechi, Shigeru Fujino, Hideki Yoshida, Akira Yoshikawa

JOURNAL OF NON-CRYSTALLINE SOLIDS 357 ( 3 ) 910 - 914 2011年2月

Optical and scintillation properties of Pr-doped Li-glass, 20Al(PO3)(3)-80LiF:Pr 3%, have been studied for applications in neutron detection systems. Based on optical transmission and reflectivity, the absorption coefficient and refractive index were calculated from the Beer Lambert law. The absorption edge was apparently shifted to the longer wavelength from 160 nm to 240 nm due to 4f -> 5d transitions of Pr ions. The strong absorption peaks of praseodymium 4f -> 4f transitions were observed from 420 nm to 500 nm and around 590 nm. The radio-luminescence spectrum excited by Am-241 5.5 MeV a source was measured. Strong emission peaks were observed around 250 nm. The alpha-ray excited pulse height spectrum and decay kinetics were also examined. Light yield was estimated to be 400 +/- 40 photons/5.5 MeV a and the main component of the decay time was evaluated to be about 12 ns. Furthermore, the pulse height spectrum of the glass excited by 252Cf neutrons was also measured, and the light yield was estimated to be 140 +/- 10 photons/neutron. (C) 2010 Elsevier B.V. All rights reserved.

RECENT DEVELOPMENTS IN FABRICATION OF NEW CONCEPTUAL GOLD CONE AND MACHINING OF POLYSTYRENE SHELL FOR FAST IGNITION TARGET 査読

H. Homma, H. Kadota, H. Hosokawa, M. Nagata, T. Fujimura, K. Nagai, M. Nakai, T. Norimatsu, H. Azechi

FUSION SCIENCE AND TECHNOLOGY 59 ( 1 ) 276 - 278 2011年1月

Recent developments of several key issues for fabrication techniques of cone and shell target for the first phase of the Fast Ignition Realization Experiment (FIREX-I) project at the Institute of Laser Engineering, Osaka University, are described in this paper. The most important modification of the target design is a double cone, and a new fabrication technique has been developed. Although the error of assembling the cones is still several microns, the first prototype of a double-cone target with a vacuum gap of 20 mu m was successfully provided for the preliminary experiment. Additionally, Ti:sapphire laser machining was used to bore a hole in the polystyrene shell.

Optical properties and structure of Pr3+-doped Al(PO3)3–LiF glasses as scattered neutron scintillator for nuclear fusion diagnostics 査読

T Murata, S Fujino, H Yoshida, Y Arikawa, T Nakazato, T Shimizu, N Sarukura, M Nakai, T Norimatsu, H Azechi, K Kamada, Y Usuki, T Suyama, A Yoshikawa, N Sato, H, Ka

IOP Conf. Series: Materials Science and Engineering 18 ( 8 ) 112006 2011年

Down-scattered neutron imaging detector for areal density measurement of inertial confinement fusion 査読

Y. Arikawa, K. Yamanoi, T. Nakazato, E. S. Estacio, T. Shimizu, N. Sarukura, M. Nakai, H. Hosoda, T. Norimatsu, Y. Hironaka, H. Azechi, N. Izumi, T. Murata, S. Fujino, H. Yoshida, K. Kamada, Y. Usuki, T. Suyama, A. Yoshikawa, N. Satoh, H. Kan

Review of Scientific Instruments 81 ( 10 ) 10D303 2010年10月

A custom developed 6Li glass scintillator (APLF80+3Pr) for down-scattered neutron diagnostics in inertial confinement fusion experiments is presented. 6Li provides an enhanced sensitivity for down-scattered neutrons in DD fusion and its experimentally observed 5-6 ns response time fulfills the requirement for down-scattered neutron detectors. A time-of-flight detector operating in the current mode using the APLF80+3Pr was designed and its feasibility observing down-scattered neutrons was demonstrated. Furthermore, a prototype design for a down-scattered neutron imaging detector was also demonstrated. This material promises viability as a future down-scattered neutron detector for the National Ignition Facility. © 2010 American Institute of Physics.

Note: Light output enhanced fast response and low afterglow Li-6 glass scintillator as potential down-scattered neutron diagnostics for inertial confinement fusion 査読

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

REVIEW OF SCIENTIFIC INSTRUMENTS 81 ( 10 ) 2010年10月

The characteristics of an APLF80+3Ce scintillator are presented. Its sufficiently fast decay profile, low afterglow, and an improved light output compared to the recently developed APLF80+3Pr, were experimentally demonstrated. This scintillator material holds promise for applications in neutron imaging diagnostics at the energy regions of 0.27 MeV of DD fusion down-scattered neutron peak at the world's largest inertial confinement fusion facilities such as the National Ignition Facility and the Laser Megajoule. (C) 2010 American Institute of Physics. [doi:10.1063/1.3488460]

Custom-designed scintillator for laser fusion diagnostics - Pr3+-doped fluoro-phosphate lithium glass scintillator 査読

Yasunobu Arikawa, Kohei Yamanoi, Tomoharu Nakazato, Elmer Surat Estacio, Toshihiko Shimizu, Nobuhiko Sarukura, Mitsuo Nakai, Takayoshi Norimatsu, Youichirou Hironaka, Hiroshi Azechi, Takahiro Murata, Shigeru Fujino, Hideki Yoshida, Kei Kamada, Yoshiyuki Usuki, Toshihisa Suyama, Akira Yoshikawa, Nakahiro Satoh, Hirohumi Kan

OPTICAL MATERIALS 32 ( 10 ) 1393 - 1396 2010年8月

A novel custom-developed scintillator for laser fusion diagnostics is reported. With the aim of diagnosing scattered neutrons from the imploded high-density fusion plasma, a fast response lithium-6 glass scintillator has been developed. Praseodymium, instead of the more widely-used cerium was chosen as the dopant. Sufficiently fast luminescence lifetime for scattered neutron diagnostics (<20 ns) was experimentally observed, and the feasibility was successfully shown in laser-fusion experiments at the GEKKO XII facility of the Institute of Laser Engineering, Osaka University. (C) 2010 Elsevier B.V. All rights reserved.

Custom-Designed Fast-Response Praseodymium-Doped Lithium 6 Fluoro-Oxide Glass Scintillator With Enhanced Cross-Section for Scattered Neutron Originated From Inertial Confinement Fusion 査読

Takahiro Murata, Shigeru Fujino, Hideki Yoshida, Yasunobu Arikawa, Tomoharu Nakazato, Toshihiko Shimizu, Nobuhiko Sarukura, Mitsuo Nakai, Takayoshi Norimatsu, Hiroshi Azechi, Kei Kamada, Yoshiyuki Usuki, Toshihisa Suyama, Akira Yoshikawa, Nakahiro Sato, Hirofumi Kan

IEEE TRANSACTIONS ON NUCLEAR SCIENCE 57 ( 3 ) 1426 - 1429 2010年6月

Scintillation properties of Pr(3+)-doped 20Al(PO(3))(3)-80 LiF glasses melted in N(2) were investigated to seek a candidate for a scattered neutron scintillator in nuclear fusion diagnostics. The fluorescence lifetime of the sample with 217 nm ultraviolet femtosecond pulse excitation was measured to be 19.5 ns. More importantly, the fluorescence lifetime with alpha particles from (241)Am radioisotope excitation was determined to be 6.7 ns. Based on our material design strategy, we have successfully developed the fast response time praseodymium-doped (6)Li glass scintillator for scattered neutron diagnostics.

Measurement of preheating due to radiation and nonlocal electron heat transport in laser-irradiated targets 査読

K. Otani, K. Shigemori, T. Kadono, Y. Hironaka, M. Nakai, H. Shiraga, H. Azechi, K. Mima, N. Ozaki, T. Kimura, K. Miyanishi, R. Kodama, T. Sakaiya, A. Sunahara

PHYSICS OF PLASMAS 17 ( 3 ) 2010年3月

This paper reports an experimental study on preheating of laser-irradiated targets. We performed temperature measurements at the rear surface of laser-irradiated targets under conditions of two different laser wavelengths (0.35 or 0.53 mu m) and several intensities (2 x 10(13) -1 x 10(14) W/cm(2)) in order to verify an effect of radiation and nonlocal electron heat transport. The preheating temperature was evaluated by observing self-emission, reflectivity, and expansion velocity at the rear surface of planar polyimide foils. The experimental results show that the x-ray radiation is dominant for preheating for 0.35-mu m laser irradiation, but contribution of nonlocal electron heat transport is not negligible for 0.53-mu m laser irradiation conditions. (C) 2010 American Institute of Physics. [doi:10.1063/1.3372099]

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