Papers - Nakai Mitsuo

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

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   2012.9

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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 Reviewed

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 )   2011.12

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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 Reviewed

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

FUSION SCIENCE AND TECHNOLOGY   60 ( 3 )   893 - 896   2011.10

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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 Reviewed

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   2011.10

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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 Reviewed

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 )   2011.8

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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 Reviewed

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 )   2011.2

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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 Reviewed

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   2011.2

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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 Reviewed

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   2011.1

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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(PO 3)3-LiF glasses as scattered neutron scintillator for nuclear fusion diagnostics Reviewed

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. Kan

IOP Conference Series: Materials Science and Engineering   18 ( 8 )   112006   2011

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Scattered neutron diagnostics is an indispensable tool for both inertial confinement and magnetic confinement fusion research. For this purpose, a fast-response neutron scintillator with a high cross section for scattered neutrons is strongly required. Recently, based on our material design strategy, we have successfully developed the fast response time Pr3+-doped 20Al(PO3)3-80LiF glass scintillator for scattered neutron originated from inertial confinement fusion. The matrix glass 20Al(PO 3)3-80LiF shows good glass forming ability, chemical durability and transparency in the deep ultraviolet region. The purpose of this work is to investigate the glass structure of 20Al(PO3) 3-80LiF glasses using Raman spectroscopy and to discuss the relationship between physical and scintillation properties and glass structure. © 2011 Ceramic Society of Japan.

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

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   2010.10

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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 Reviewed

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 )   2010.10

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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 Reviewed

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   2010.8

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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 Reviewed

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   2010.6

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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 Reviewed

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 )   2010.3

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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]

Experimental investigation to demonstrate Impact Fast Ignition scheme Reviewed

T. Watari, H. Azechi, M. Nakai, Y. Hironaka, T. Sakaiya, H. Nakamura, H. Shiraga, K. Shigemori, H. Hosoda, Y. Arikawa, H. Homma, T. Norimatsu, M. Murakami, T. Jhozaki, M. Karasik, J. Gardner, J. Bates, D. Colombant, J. Weber, Y. Aglitsky, S. Obenschain

SIXTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, PARTS 1-4   244   2010

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We have proposed a new ignition scheme of Fast Ignition, called "Impact Fast Ignition (IFI)", in which a compressed fuel is ignited by impact collision of a fragment of separately imploded fuel. We performed integrated experiments on impact ignition, in which a portion of a deuterated polystyrene (CD) shell was accelerated to about 600 km/s and was collided with precompressed CD fuel. The shell was imploded using 9 beams and the impactor was accelerated using 3 beams of the GEKKO XII laser system. The laser energy was 350 J per beam. The kinetic energy of the impactor was efficiently converted into thermal energy generating a temperature of about 1.8 keV., Observed maximum neutron yield was 2x10(6). This yield was 80 times as large as that without impactor. We will present the experimental details and results, demonstrating the high potential of impact ignition for fusion energy production.

Industrial Applications of Laser Neutron Source Reviewed

S. Nakai, K. Mima, Y. Kato, K. Tanaka, Y. Ikeda, H. Azechi, K. Miyanaga, M. Nakai, M. Perlado, R. Gonzalez Arrabal

SIXTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, PARTS 1-4   244   2010

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The industrial applications of the intense neutron source have been widely explored because of the unique features of the neutron-matter interaction. Usually, intense neutron sources are assembled with fission reactors or high energy ion accelerators. The big size and high cost of these systems are the bottle neck to promote the industrial applications of intense neutrons. In this paper, we propose the compact laser driven neutron source for the industrial application. As the first step of our project for the versatile applications of laser driven neutron source, Li-neutron and/or Li-proton interactions have been investigated for the application to the development of Li battery.

Hugoniot and temperature measurements of liquid hydrogen by laser-shock compression Reviewed

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

SIXTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, PARTS 1-4   244   2010

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Hydrogen at high pressure in the fluid state is of great interest for target design of inertial confinement fusion and understanding the interior structure of gas giant planets. In this work, we successfully obtained the Hugoniot data for liquid hydrogen up to 55 GPa under laser-driven shock loading using impedance matching to a quartz standard. The shocked temperature was determined simultaneously by the brightness temperature. The compression and temperature along the principal Hugoniot are in good agreement with theoretical models. High reflectivity of hydrogen was observed at 40 GPa, which suggests the fluid becomes conducting

High-speed monochromatic x-ray imager for electron temperature mapping of fast igniter plasmas Reviewed

Minoru Tanabe, Takashi Fujiwara, Shinsuke Fujioka, Nobuo Hayashi, Hiroaki Nishimura, Takeshi Fujimura, Mitsuo Nakai, Keiji Nagai, Hirofumi Homma, Hiroyuki Shiraga, Takayoshi Norimatsu, Hiroshi Azechi, Kunioki Mima

SIXTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, PARTS 1-4   244   2010

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We report on experiments aimed at obtaining laser-imploded core plasma temperature maps using two color, monochromatic x-ray imager. This instrument uses two toroidally bent Bragg crystals and a high-speed sampling imager to provide spatial resolution of 25 mu m, temporal resolution of 20 ps, and spectral resolution over 200, simultaneously. Using a deuterated plastic shell target filled with CHClF(2) gas, time-resolved monochromatic x-ray images in the Cl-He(beta) and Cl-Ly(beta) were successfully obtained.

Laser Machining for Fabrication of Targets used in the FIREX-I project Reviewed

T. Fujimura, M. Nakai, A. Iwamoto, N. Hayashi, M. Tanabe, Yu. Izawa, K. Nagai, H. Homma, H. Nishimura, T. Norimatsu, H. Azechi

SIXTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, PARTS 1-4   244   2010

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This paper reports on way to fabricate a gas-tight targets dedicated for the first stage of Fast Ignition Realization Experiment (FIREX-I) at the Institute of Laser Engineering (ILE), Osaka University. It was found that a Ti;sapphire laser machining can be used to fabricate the target. The performance of the laser machining using a fs Ti; sapphire laser was examined on shell materials. The conditions for accurate machining were determined. Michelson interferometer with two different wavelengths which imitates a white light interferometer is an excellent tool for confirming the gas-tightness of the target after assembly.

A SCATTERED-NEUTRON DETECTOR FOR AREAL DENSITY MEASUREMENT Reviewed

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

SIXTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, PARTS 1-4   244   2010

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Experimental results are presented on the neutron scintillating properties of a custom-designed Praseodymium-doped Lithium-6 glass for a new deuterium-deuterium (DD) fusion scattered-neutron detector. Luminescence was observed at 278 nm-wavelength, and time-resolved measurement yielded similar to 5.4 ns decay time for neutron excitation. Actual time-of-flight data in laser fusion experiments at the GEKKO XII facility at the Institute of Laser Engineering (ILE), Osaka University reveal that it can clearly discriminate fusion primary-neutrons from the x-ray signals. This material promises the realization of more accurate DD fusion scattered-neutron diagnostics. Design work for a scattered-neutron detector is being conducted for the Fast Ignition Realization Experiment (FIRE-X) at ILE.