研究者詳細 - 中井　光男

論文 - 中井　光男

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Encapsulation of low density materials for the first stage of fast ignition realization experiment (FIREX-I) - Control of microstructure and gelation process using a phase-transfer catalyst and tailored polymers 査読

Keiji Nagai, F. Ito, H. Yang, A. Iwamoto, M. Nakai, H. Homma, H. Shiraga, H. Azechi, K. A. Tanaka, R. Kodama, T. Norimatsu, K. Mima

22ND IEEE/NPSS SYMPOSIUM ON FUSION ENGINEERING 33 - + 2007年

Development of foam capsule fabrication for cryogenically cooled fuel targets is overviewed in the present paper. The fabrication development was initiated as a part of the Fast Ignition Realization Experiment (FIREX) Project at the ILE, Osaka University in the way of bilateral collaboration between Osaka University and National Institute for Fusion Science (NIFS). For the first stage of FIREX (FIREX-1), a foam cryogenic target was designed where low-density foam shells with a conical fight guide will be cooled down to the cryogenic temperature and will be fueled through a narrow pipe. The required diameter and thickness of the capsule are 500 pm and 20 [km, respectively. The material should be low-density plastics foam. We have prepared such capsules using 1) new material of (phloroglucinolcarboxylic acid)/formalin resin to control kinematic viscosity of the precursor, 2) phase-transfer-catalyzed gelation process to keep density matching of three phases of the emulsion. 3) non-volatile silicone oil as outer oil of emulsion in order to prevent hazard halogenated hydrocarbon and flammable mineral oil. The obtained foam capsule had fine structure of 180 nm (outer surface) to 220 nm (inner surface) and uniform thickness reaching to resolution limit of optical analysis (similar to 0.5 mu m). A small hole was made before the solvent exchange and the drying process to prevent distortion due to volume changes. The density of dried foam was 0.29 g/cm(3). After attaching the petawatt laser guiding cone and fueling glass tube, poly([2,2]paracyclophane) was coated on the foam surface and supplied for a fueling test of cryogenic hydrogen.

Progress of impact fast ignition

M. Murakami, H. Nagatomo, T. Sakaiya, S. Fujioka, H. Saito, H. Shiraga, M. Nakai, K. Shigemori, H. Azechi, M. Karasik, J. Gardner, J. Bates, D. Colombant, J. Weaver, A. Schmitt, A. Velikovich, Y. Aglitskiy, J. Sethian, S. Obenshain

34th EPS Conference on Plasma Physics 2007, EPS 2007 - Europhysics Conference Abstracts 31 ( 1 ) 21 - 24 2007年

プラズマ燃焼実験のための先進計測 5.レーザー慣性核融合の燃焼の物理と計測-高速点火実験のための先進計測-

疇地宏, 兒玉了祐, 田辺稔, 反保元伸, 中井光男, 中村浩隆, 西村博明, 藤岡慎介, 古河裕之, 細田裕計, 渡利威士

プラズマ・核融合学会誌 83 ( 12 ) 2007年

Fabrication of low-density solid xenon as laser-produced plasma extreme ultraviolet source 査読

Mizuho Nagata, Takayoshi Norimatsu, Mitsuo Nakai, Keiji Nagai, Nobuyoshi Ueda, Shinsuke Fujioka, Tatsuya Aota, Hiroaki Nishimura, Katsunobu Nishihara, Noriaki Miyanaga, Yasukazu Izawa, Kunioki Mima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 45 ( 33-36 ) L884 - L886 2006年9月

A low-density solid xenon (Xe) target has been developed as laser-produced plasma (LPP) extreme ultraviolet (EUV) source. Xe gas was cooled to below the condensation temperature, and liquid Xe was sprayed from a swirl atomizer into a low-pressure atmosphere. Microparticles of liquid Xe were rapidly cooled by their own latent heat of evaporation, and became a solid micrometer-sized powder. The most frequent particle diameter under an atomizing pressure of 0.3 MPa was 114 mu m, and the apparent density was 0.2 g/cm(3) 1/13 of the density of conventional solid Xe. The apparent production rate of the powder was 2.2 cm(3)/s.

Extreme ultraviolet emission from laser-irradiated low-density Xe targets 査読

Nobuyoshi Ueda, Mizuho Nagata, Hiroaki Nishimura, Shinsuke Fujioka, Tatsuya Aota, Yuzuri Yasuda, Yuichi Inubushi, Tsuyoshi Ando, Takayoshi Norimatsu, Mitsuo Nakai, Keiji Nagai, Katsunobu Nishihara, Atsushi Sunahara, Noriaki Miyanaga, Yasukazu Izawa, Kunioki Mima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 45 ( 7 ) 5951 - 5953 2006年7月

The effect of the initial density of xenon (Xe) targets on extreme ultraviolet (EUV) emission has been investigated. With decreasing initial density, it was found that the spectral width around 11 nm becomes broad, and the intensity of 13.5 nm emission increases. The maximum conversion efficiency (CE) for solid Xe targets is approximately 0.6% at a 2 x 10(11) W/cm(2) of laser intensity, whereas that for the low-density targets is approximately 0.7% at a 4 x 10(11) W/cm(2). The spectral broadening with decreasing initial density can be attributed to the change in optical thickness of laser-produced plasmas. The enhancement of CE is attributed to optically thick plasma formation.

Conceptual design of laser fusion reactor KOYO-fast - Target design and the fueling system 査読

T. Norimatsu, T. Johzaki, H. Azechi, K. Mima, Y. Nakao, H. Sakagami, H. Shiraga, R. Kodama, H. Nagatomo, T. Endo, A. Iwamoto, H. Yoshida, M. Nakai

JOURNAL DE PHYSIQUE IV 133 841 - 843 2006年6月

Preliminary results on the cryogenic target for FIREX project 査読

A. Iwamoto, R. Maekawa, T. Mito, M. Okamoto, O. Motojima, M. Nakai, T. Norimatsu, K. Nagai

JOURNAL DE PHYSIQUE IV 133 899 - 901 2006年6月

Preliminary tests on the cryogenic target for the fast ignition realization experiment (FIREX) project has been conducted. A foam shell method is proposed to realize its target design. A foam target consists of three parts: a foam shell, a conical laser guide and a liquid or gas feeder made of glass. The shell is a hollow sphere (500 pm in diameter) with a uniform and thin foam layer (similar to 20 mu m in thickness). Epoxy resin is utilized to assemble the parts into the target. Regarding target fabrication, one of the concerns is the influence on various thermal contractions from the different materials when it is cooled down to cryogenic environment. This paper describes the result on the validity check at cryogenic environment and the demonstration of H-2 liquefaction using a dummy target instead of the foam target.

Recent results and future prospects of laser fusion research at ILE, Osaka 査読

K. Mima, K. A. Tanaka, R. Kodama, T. Johzaki, H. Nagatomo, H. Shiraga, N. Miyanaga, M. Murakami, H. Azechi, M. Nakai, T. Norimatsu, K. Nagai, T. Taguchi, H. Sakagami

JOURNAL DE PHYSIQUE IV 133 27 - 28 2006年6月

Electrochemical fabrication of low density metal foam with mono-dispersed-sized micro- and submicro-meter pore 査読

K Nagai, D Wada, M Nakai, T Norimatsu

FUSION SCIENCE AND TECHNOLOGY 49 ( 4 ) 686 - 690 2006年5月

This paper deals with the fabrication of low-density metal using micro-template and electrochemical plating techniques. Tin and gold foam films were demonstrated For both cases, porous foam plating required 0.5 V negatively higher bias potential than that for conventional metal plating. The electric current density values for them are smaller than those for bulk metal plating. In spite of these differences, the coulomb efficiency was almost the same as those for bulk metal plating. The density was almost close to the rest of closed packing density; 23 % of bulk metal for gold and 20 % of bulk metal for tin. These low-density foams will be applied for extreme ultraviolet (EUV) generation or other application through laser produced plasma.

Hugoniot measurement of diamond under laser shock compression up to 2 TPa 査読

H Nagao, KG Nakamura, K Kondo, N Ozaki, K Takamatsu, T Ono, T Shiota, D Ichinose, KA Tanaka, K Wakabayashi, K Okada, M Yoshida, M Nakai, K Nagai, K Shigemori, T Sakaiya, K Otani

PHYSICS OF PLASMAS 13 ( 5 ) 2006年5月

Hugoniot data of diamond was obtained using laser-driven shock waves in the terapascal range of 0.5-2 TPa. Strong shock waves were generated by direct irradiation of a 2.5 ns laser pulse on an Al driver plate. The shock wave velocities in diamond and Al were determined from optical measurements. Particle velocities and pressures were obtained using an impedance matching method and known Al Hugoniot. The obtained Hugoniot data of diamond does not show a marked difference from the extrapolations of the Pavlovskii Hugoniot data in the TPa range within experimental errors. (c) 2006 American Institute of Physics.

Optimization of gelation to prepare hollow foam shell of resorcinol-formalin using a prase-transfer catalyst 査読

F Ito, K Nagai, M Nakai, T Norimatsu

FUSION SCIENCE AND TECHNOLOGY 49 ( 4 ) 663 - 668 2006年5月

We studied the gelation of an RF foam shell using a phase-transfer catalyst and density-match non-volatile silicon oil. A phase-transfe catalyst circumvent the problem of density-mismatch and achieve gelation at room temperature, by which the catalyst is contained in the outer oil (O-o,) phase, and is then gradually transferred into the RF droplets. For the O-o phase, we used non-volatile silicon oil as a non-hazardous material instead of a toxic (mineral oil)/carbontetrachloride.
Vigorous agitation conditions were optimized based on three experiments. An emulsion was produced using a droplet generator, and was injected into a drum containg a mixture of 0.39% acetic acid and silicon oil. The drum was rotated and its speed were increased to 95 rpm within 15 minutes. Five minutes later, the rotation speed was increased to 120 rpm (maximum rotation speed), which was maintained for 1 minute, there after reduced to 95 rpm for 39 minutes.

Polystyrene based foam materials for cryogenic targets of fast ignition realization experiment (FIREX) 査読

N Nemoto, K Nagai, Y Ono, K Tanji, T Tanji, M Nakai, T Norimatsu

FUSION SCIENCE AND TECHNOLOGY 49 ( 4 ) 695 - 700 2006年5月

This paper deals with the development of materials without volume change in the formation of uniform low density foam capsules with fine structures. Two monomers, i.e., 5-(4-vinylbenzyl)oxymethyl-5-methyl-1,3dioxane-2-thione (M1) and 4-vinylphenyloxirane (M2), were prepared as the comonomers polymerized with styrene. Polystyrene-based copolymers using styrene and M1 or M2 were prepared by free radical copolymerization using azobis(isoburyronitrile) (AIBN) as an initiator. The solutions of the obtained polystyrene-based copolymers in benzenel/dichloromethane mixture or 4-chlorotoluene were gelated by the addition of a cationic initiator, which caused cross-linking via ring-opening polymerization of the pendant cyclic moieties. The gel was transformed into an aerogel by exchanging solvent to 2-propanol, and removal of 2-propanol using supercritical CO2. SEM images of a cross sectional view of the aerogel indicated that sub-micrometer voids were distributed randomly, and most of parts look filled bulk morphology. The density of the gel obtained from the present polystyrene-based copolymers was estimated to be 200 mg/cm(3), which implies existence of vacancies without observation in the SEM image, suggesting the extremely fine cell structure.

Tin-polymer composite on a rotating drum as a high repetition rate laser target for extreme ultraviolet generation 査読

Y Yasuda, QC Gu, K Nagai, M Nakai, T Norimatsu, S Fujioka, H Nishimura, M Nakatsuka

FUSION SCIENCE AND TECHNOLOGY 49 ( 4 ) 691 - 694 2006年5月

High repetition rate irradiation of a laser on target is necessary for practical operation of an extreme ultraviolet (EUV) light source. A rotating drum with a tin composite film was fabricated for this purpose. Uniformly tin-dispersed plastic film was prepared from hydroxypropyl cellulose (HPC) and tin source solution of SnCl4/ethanol/H2O. It was transparent in the visible to near infrared region. The film was coated on an aluminum rotating drum from HPC-Sn solution. When this solution was coated on aluminum rotating target drum directly, the drum was corroded. Therefore an alternative method was developed starting with tin(tertbutoxide) instead of SnCl4. The later solution was used for coating on aluminum rotating target drum directly.

Low-density-plastic-foam capsule of resorcinol/formalin and (phloroglucinolcarboxylic acid)/formalin resins for fast-ignition realization experiment (FIREX) in laser fusion research 査読

F Ito, K Nagai, M Nakai, T Norimatsu, A Nikitenko, S Tolokonnikov, E Koresheva, T Fujimura, H Azechi, K Mima

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 45 ( 8-11 ) L335 - L338 2006年3月

In this report, we describe fuel (deuterium and tritium) Capsule preparation for the fast-ignition realization experiment (FIREX) in laser fusion research. The required diameter and thickness of the capsule are 500 and 20 pill, respectively. The material Should be plastics with low-density foam. We have prepared such a capsule using (1) a new material of (phloroglucinolcarboxylic acid)/formalin resin to control the kinematic viscosity of the precursor, (2) the phase-transfer-catalyzed gelation process to maintain the density matching of the emulsion. The obtained foam capsule had a fine structure of 180 run (outer surface) to 220 run (inner surface) size and a uniform thickness reaching the resolution limit of optical analysis (similar to 0.5 mu m).

Cool-down performance of the apparatus for the cryogenic target of the FIREX project 査読

A. Iwamoto, R. Maekawa, T. Mito, M. Okamoto, O. Motojima, S. Sugito, K. Okada, M. Nakai, T. Norimatsu, K. Nagai

Fusion Engineering and Design 81 ( 8-14 PART B ) 1647 - 1652 2006年2月

The apparatus for cryogenic target experiments of the Fast Ignition Realization EXperiment (FIREX) project has been developed at the National Institute for Fusion Science (NIFS). To achieve the target specifications for the project, the foam shell method has been proposed. The Institute of Laser Engineering (ILE), Osaka University and NIFS have started a cooperative study of the method. NIFS is responsible for the demonstration of the fuel layering process. The first cool-down test of the apparatus was conducted. Its cool-down performance is described in this paper. © 2005 Elsevier B.V. All rights reserved.

Angular distribution control of extreme ultraviolet radiation from laser-produced plasma by manipulating the nanostructure of low-density SnO2 targets 査読

K Nagai, QC Gu, ZZ Gu, T Okuno, S Fujioka, H Nishimura, YZ Tao, Y Yasuda, M Nakai, T Norimatsu, Y Shimada, M Yamaura, H Yoshida, M Nakatsuka, N Miyanaga, K Nishihara, Y Izawa

APPLIED PHYSICS LETTERS 88 ( 9 ) 2006年2月

We have found that the divergence of a relatively monochromatic extreme ultraviolet (EUV) emission from a laser-produced plasma can be manipulated by changing the target morphology which is a porous low-density tin oxide (SnO2) structure. The fundamental light of a Nd-YAG laser was irradiated on the target with laser intensity of similar to 10(11) W/cm(2) and pulse duration of 10 ns. The nanostructure and density of the targets were tuned by a combination of colloidal polymer template and sol-gel processes [Gu, Nagai, Norimatsu, Fujioka, Nishimura, Nishihara, Miyanaga, and Izawa, Chem. Mater. 17, 1115 (2005)], which has a merit in large-scale preparation. When the target has an open cell nanostructure, the EUV emission directed predominantly along target normal, while a closed cell target exhibited divergent emission. The angular distribution may be affected by the orientation of the microstructured initial target, and this phenomenon can be applied to wavefront control of EUV emission.

Ultrafast x-ray imaging with sliced sampling streak cameras 査読

TX Huang, M Nakai, H Shiraga, H Azechi, TX Huang, YK Ding, ZJ Zheng

REVIEW OF SCIENTIFIC INSTRUMENTS 77 ( 2 ) 2006年2月

Polymorphic tin dioxide synthesis via sol-gel mineralization of ethyl-cyanoethyl cellulose lyotropic liquid crystals 査読

Qincui Gu, Keiji Nagai, Mitsuo Nakai, Takayoshi Norimatsu

Colloid and Polymer Science 284 ( 4 ) 429 - 434 2006年1月

The polymorphic tin dioxide (SnO2) was synthesized by calcinating the sol-gel mineralized hybrid of the tin source solution (SnC14/ethanol/H2O) and the lyotropic liquid crystal of ethyl-cyanoethyl cellulose((E-CE)C)/acrylic acid (AA). The sub-micrometer SnO2 spheres with bimodal distribution at 370 and 860 nm were obtained after calcinating the hybrid at 400 °C for 5 h. When the hybrid was exposed to ultraviolet first and then calcinated the flying-saucer-like SnO2 was formed. The exposure time was found to influence the morphology of the as-prepared SnO2. Except for the spherical and the flying-saucer-like SnO2, a small amount of well-developed polyhedral SnO2 was also observed in the as-prepared samples. On this basis, the lyotropic liquid crystal of (E-CE)C/AA afforded a novel route to obtain polymorphic SnO2. © Springer-Verlag 2005.

Equation of state of diamond under shock compression up to 2 TPa 査読

H. Nagao, K. G. Nakamura, K. Kondo, N. Ozaki, T. Ono, K. Takamatsu, K. A. Tanaka, K. Nagai, M. Nakai, K. Wakabayashi, K. Okada, M. Yoshida

Shock Compression of Condensed Matter - 2005, Pts 1 and 2 845 111 - 114 2006年

The equation of state of diamond was studied using laser-driven shock waves in a terapascal region between 0.5 and 2 TPa. Strong shock waves were generated by direct irradiation of a 2.5 ns laser pulse on an Al driver plate. The shock wave velocities in the diamond and Al were measured optically. Particle velocities and pressures were obtained using impedance matching and the known Al Hugoniot. The dependence of U-s(Dia)(u(p)(Dia)) obtained for single crystalline diamond is well-approximated by U-s(Dia)=11.2+1.2u(p)(Dia) for the obtained Hugoniot data, all previous experimental data, and the bulk sound velocity.

Observation of Xenon EUV Spectra in Compact Helical System 査読

SUZUKI Chihiro, NISHIMURA Hiroaki, SONG Mi-Young, KATO Takako, OKAMURA Shoichi, MORE Richard, NISHIHARA Katsunobu, NAKAI Mitsuo, SHIGEMORI Keisuke, FUJIOKA Shinsuke, OGAWA Hiroaki, SASAKI Akira

Journal of Plasma and Fusion Research SERIES 7 73 - 76 2006年

We have carried out spectroscopic measurements of xenon (Xe) extreme ultraviolet (EUV) emissions in plasmas produced by a medium-size fusion-oriented torus device, Compact Helical System (CHS), for the development of reliable spectroscopic data of Xe ions. The EUV spectra have been measured in low density (<1019 m?3) hydrogen plasma with Xe gas injection by an existing grazing incidence spectrometer. Electron density and temperature profiles are measured by Thomson scattering diagnostic. Observed spectral lines arecompared with the results of HULLAC code calculation and charge exchanging collisions experiment. The charge states of Xe ions and transitions are inferred for several prominent peaks.

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