論文 - 中井　光男

Characterization of extreme UV radiation in laser produced plasma for use in lithography 査読

Nishimura H, Shigemori K, Nakai M, Fujioka S, Shimada Y, Hashimoto K, Yamaura M, Uchida S, Matsui R, Hibino T, Okuno T, Tao Y, Nagai K, Norimatsu T, Nagatomo H, Zhakhovckii V, Furukawa H, Sunahara A, Kawamura T, Murakami M, Nishihra K, Miyanaga N, Nakatsuka M, Izawa Y

Inertial Fusion Sciences and Applications 2003   1077 - 1080   2004年

Estimation of emission efficiency for laser-produced EUV-plasmas 査読

T Kawamura, A Sunahara, K Gamada, K Fujima, F Koike, H Furukawa, T Nishikawa, A Sasaki, T Kagawa, R More, T Kato, M Murakami, Zhakhovskii, V, H Tanuma, T Fujimoto, Y Shimada, M Yamaura, K Hashimoto, S Uchida, C Yamanaka, T Okuno, T Hibino, N Ueda, R Matsui, YZ Tao, M Nakai, K Shigemori, S Fujioka, K Nagai, T Norimatsu, H Nishimura, K Nishihara, N Miyanaga, Y Izawa

EMERGING LITHOGRAPHIC TECHNOLOGIES VIII   5374   918 - 925   2004年

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Extreme Ultra Violet (EUV) light source produced by laser irradiation emits not only the desired EUV light of 13 similar to 14 nm (about 90 eV) but also shorter x-rays. For example, emissions around. 4 similar to 8 nm (about 150 similar to 300 eV) and 1 similar to 2.5 nm (about 0.5 similar to 1.2 keV) are experimentally observed from Sn and/or SnO2 plasmas. These emissions are correspond to the N-shell and M-shell transitions, respectively. From the view point of energy balance and efficiency, these transitions should be suppressed. However, they may, to some extent, contribute to provide the 5p and 4f levels with electrons which eventually emit the EUV light and enhance the intensity. To know well about radiative properties and kinematic of the whole plasma, atomic population kinetics and spectral synthesis codes have been developed. These codes can estimate the atomic population with nl-scheme and spectral shapes of the EUV light. Radiation hydrodynamic simulation have been proceeding in this analysis. Finally, the laser intensity dependence of the conversion efficiency calculated by these codes agrees with that of the corresponding experimental results.

Characterization of GEKKO/HIPER-driven shock waves for equation-of-state measurements in ultra-high pressure regime

Takamatsu Kikuo, Yamanaka Tatsuhiko, Azechi Hiroshi, Miyanaga Noriaki, Nakai Mitsuo, Ono Takatoshi, Nagai Keiji, Shigemori Keisuke, Ozaki Norimasa, Tanaka Kazuo A.

Journal of Plasma and Fusion Research   vol. 80, pp. 486-491 ( 6 )   486 - 491   2004年

Experimental study on ablative stabilization of Rayleigh-Taylor instability of laser-irradiated targets 査読

K Shigemori, T Sakaiya, K Otani, S Fujioka, M Nakai, H Azechi, H Shiraga, Y Tamari, K Okuno, A Sunahara, H Nagatomo, M Murakami, K Nishihara, Y Izawa

HIGH-POWER LASER ABLATION V, PTS 1 AND 2   5448   634 - 641   2004年

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Hydrodynamic instabilities are key issues of the physics of inertial confinement fusion (ICF) targets. Among the instabilities, Rayleigh-Taylor (RT) instability is the most important because it gives the largest growth factor in the ICF targets. Perturbations on the laser irradiated surface grow exponentially, but the growth rate is reduced by ablation flow. The growth rate gamma is written as Takabe-Betti formula: gamma = (kg/(1+kL))(1/2). -betakm/rho(a), where k is wave number of the perturbation, g is acceleration, L is density scale-length, beta is a coefficient, m is mass ablation rate per unit surface, and rho(a), is density at the ablation front. We experimentally measured all the parameters in the formula for polystyrene (CH) targets. Experiments were done on the RIPER laser facility at Institute of Laser Engineering, Osaka University. We found that the beta value in the formula is similar to 1.7, which is in good agreements with the theoretical prediction, whereas the beta for certain perturbation wavelengths are larger than the prediction. This disagreement between the experiment and the theory is mainly due to the deformation of the cutoff surface, which is created by non-uniform ablation flow from the ablation surface. We also found that high-Z doped plastic targets have multiablation structure, which can reduce the RT growth rate. When a low-Z target with high-Z dopant is irradiated by laser, radiation due to the high-Z dopant creates secondary ablation front deep inside the target. Since, the secondary ablation front is ablated by x-rays, the mass ablation rate is larger than the laser-irradiated ablation surface, that is, further reduction of the RT growth is expected. We measured the RT growth rate of Br-doped polystyrene targets. The experimental results indicate that of the CHBr targets show significantly small growth rate, which is very good news for the design of the ICF targets.

Experimental study on basic properties of laser-produced EUV plasmas on GEKKO-XII laser facility 査読

K Shigemori, M Nakai, Y Shimada, M Yamaura, K Hashimoto, S Fujioka, H Nishimura, S Uchida, A Sunahara, K Nishihara, N Miyanaga, Y Izawa

EMERGING LITHOGRAPHIC TECHNOLOGIES VIII   5374   971 - 978   2004年

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Extremely ultraviolet (EUV) light at around 13.5 nm of wavelength is the most probable candidate of the light source for lithography for semiconductors of next generation. We have been studying about the EUV light source from laser-produced plasma. Detailed understanding of the EUV plasma is required for developments of modeling with simulation codes. Several parameters should be experimentally measured to develop the important issues in the simulation codes. We focused on density profile, properties of EUV emission, and opacity of the laser-produced plasmas. We present recent experimental results on these basic properties of the laser-produced EUV plasmas.

Rayleigh-taylor instability and its reduction in laser-accelerated targets 査読

Shiraga H, Shigemori K, Nakai M, Sakaiya T, Fujioka S, Tamari Y, Azechi H, Nishihara K, Sunahara A, Nagatomo H, Ikegawa T, Ohnishi N, Nagai K, Norimats T, Yamanaka T

Inertial Fusion Sciences and Applications 2003   115 - 120   2004年

Reduction of the Rayleigh-Taylor instability growth with multi-color laser irradiation 査読

Shigemori K, Otani K, Sakaiya T, Sunahara A, Fujioka S, Nakai M, Shiraga H, Azechi H, Nishihara K

Inertial Fusion Sciences and Applications 2003   186 - 189   2004年

Theoretical modeling of laser-produced plasmas for development of extreme UV radiation source for lithography 査読

Nishihara K, Nishikawa T, Sasaki A, Kawamura T, Sunahara A, Furukawa H, Murakami M, Nishimura H, Shimada Y, Nakai M, Fujioka S, Shigemori K, Uchida S, Fujima K, More R, Koike F, Kagawa T, Zhakhovskii V, Hashimoto K, Yamaura M, Matsui R, Hibino T, Okuno T, Tao Y, Sohnatzadeh F.L, Nagai K, Norimatsu T, Tanuma H, Miyanaga N, Izawa Y

Inertial Fusion Sciences and Applications 2003   1069 - 1073   2004年

First observation of density profile in directly laser-driven polystyrene targets for ablative Rayleigh-Taylor instability research 査読

S Fujioka, H Shiraga, M Nishikino, K Shigemori, A Sunahara, M Nakai, H Azechi, K Nishihara, T Yamanaka

PHYSICS OF PLASMAS   10 ( 12 )   4784 - 4789   2003年12月

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The temporal evolution of the density profile of a directly laser-driven polystyrene target was observed for the first time using an x-ray penumbral imaging technique coupled with side-on x-ray backlighting at the GEKKO XII [C. Yamanaka , IEEE J. Quantum Electron. QE-17, 1639 (1981)]-High Intensity Plasma Experimental Research laser facility (I-L=0.7x10(14) W/cm(2), lambda(L)=0.35 mum). This density measurement makes it possible to experimentally confirm all physical parameters [gamma(k),k,g,m,rho(a),L-m] appearing in the modified Takabe formula for the growth rate of the ablative Rayleigh-Taylor instability. The measured density profiles were well reproduced by a one-dimensional hydrodynamic simulation code. The density measurement contributes toward fully understanding the ablative Rayleigh-Taylor instability. (C) 2003 American Institute of Physics.

Equation-of-state measurements of polyimide at pressures up to 5.8 TPa using low-density foam with laser-driven shock waves 査読

K Takamatsu, N Ozaki, KA Tanaka, T Ono, K Nagai, M Nakai, T Watari, A Sunahara, M Nakano, T Kataoka, H Takenaka, M Yoshida, K Kondo, T Yamanaka

PHYSICAL REVIEW E   67 ( 5 )   2003年5月

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The laser-driven equation-of-state (EOS) experiments for polyimide are presented. The experiments were performed with emission measurements from the rear sides of shocked targets at up to a laser intensity of 10(14) W/cm(2) or higher with 351 nm wavelength and 2.5 ns duration. Polyimide Hugoniot data were obtained up to 0.6 TPa with good accuracy. Applying low-density foam ablator to the EOS unknown material, we also obtained the data at a highest pressure of 5.8 TPa in the nonmetal materials. Those data were in agreement with the theoretical curves.

Side-on measurement of hydrodynamics of laser-driven plasmas with high space- and time-resolution x-ray imaging technique 査読

S Fujioka, H Shiraga, M Nishikino, Y Tamari, K Shigemori, M Nakai, H Azechi

REVIEW OF SCIENTIFIC INSTRUMENTS   74 ( 3 )   2198 - 2201   2003年3月

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We developed and improved high space- and time-resolution x-ray imaging techniques (3-6 mum, 100-200 ps). These techniques were coupled with side-on x-ray backlighting for observing hydrodynamics of directly laser-driven polystyrene plasmas. As a high sensitive x-ray image detector, Imaging Plate was introduced to penumbral imaging technique [S. Fujioka et al, Rev. Sci. Instrum. 73, 2588 (2002)]. Noise in penumbral images was reduced by this improvement, and high quality density profiles of plasmas were obtained. A large-magnification slit camera, whose-slit width and magnification were 4 mum and 82.8, was coupled with an x-ray streak camera (XSC). Due to the advantage of the large-magnification, high spatial resolution of 5.8 mum was found even with an XSC, the photocathode of which usually has low spatial resolution. These techniques are useful in understanding of hydrodynamic instability in inertial confinement fusion. (C) 2003 American Institute of Physics.

Temporal evolution of temperature and density profiles of a laser compressed core (invited) 査読

Y Ochi, Golovkin, I, R Mancini, Uschmann, I, A Sunahara, H Nishimura, K Fujita, S Louis, M Nakai, H Shiraga, N Miyanaga, H Azechi, R Butzbach, E Forster, J Delettrez, J Koch, RW Lee, L Klein

REVIEW OF SCIENTIFIC INSTRUMENTS   74 ( 3 )   1683 - 1687   2003年3月

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Temporal evolutions of the electron temperature and density profiles in the inertial confinement fusion core plasma were obtained through a combination of experimental technology to create a uniform core, diagnostics developments,,and a data analysis technique to obtain an optimal solution. In the experiment, time- and space-resolved x-ray spectroscopic measurements were carried out; an x-ray streak spectrograph and a monochromatic x-ray framing camera provided temporal evolution of x-ray spectrum and monochromatic emissivities, respectively. The spectrum and emissivity profile were iteratively fitted as a function of electron temperature, density, and space. Then, optimal solutions were successfully extracted with the help of Niched-Pareto genetic algorithm. Temporal behavior between those data is well corrected by comparing spatially and spectrally integrated intensities. The resultant profiles were compared with hydrocode simulations, showing that spatially averaged electron temperature and density evolutions are well replicated by the simulations, but their detail spatial profiles do not agree with them. (C) 2003 American Institute of Physics.

X-ray imaging diagnostics for laser-driven hydrodynamic instability experiments 査読

H Shiraga, H Azechi, M Nakai, K Shigemori, M Nishikino, T Sakaiya, S Fujioka, Y Tamari, T Yamanaka

REVIEW OF SCIENTIFIC INSTRUMENTS   74 ( 3 )   2194 - 2197   2003年3月

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Rayleigh-Taylor (RT) instability is one of the most important physical issues in the inertial confinement fusion research. The reduction of its growth rate due to laser-driven ablation, which is described by the modified Takabe formula, is of great importance for-a precise understanding of the target physics. We have developed various diagnostic techniques for the measurement of the parameters appearing in the Takabe formula, such as the growth rate, the acceleration, the mass ablation rate, and the density structure including ablation density and density scalelength. Face-on and side-on x-ray backlighting were coupled with moire interferometry imaging, penumbral imaging, and Fresnel zoneplate imaging. All the physical parameters related to RT instability were measured experimentally, and compared with simulation results. (C) 2003 American Institute Of Physics.

Equation-of-state measurements of polyimide at pressures up to 5.8 TPa using low-density foam with laser-driven shock waves 査読

K. Takamatsu, N. Ozaki, K. A. Tanaka, T. Ono, K. Nagai, M. Nakai, T. Watari, A. Sunahara, M. Nakano, T. Kataoka, H. Takenaka, M. Yoshida, K. Kondo, T. Yamanaka

Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics   67 ( 5 )   5   2003年

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The laser-driven equation-of-state (EOS) experiments for polyimide are presented. The experiments were performed with emission measurements from the rear sides of shocked targets at up to a laser intensity of [Formula presented] or higher with 351 nm wavelength and 2.5 ns duration. Polyimide Hugoniot data were obtained up to 0.6 TPa with good accuracy. Applying low-density foam ablator to the EOS unknown material, we also obtained the data at a highest pressure of 5.8 TPa in the nonmetal materials. Those data were in agreement with the theoretical curves. © 2003 The American Physical Society.

High-speed x-ray radiographic measurement of laser-driven hydrodynamic instability 査読

H Shiraga, H Azechi, M Nakai, K Shigemori, M Nishikino, T Sakaiya, S Fujioka, Y Tamari, T Yamanaka

25TH INTERNATIONAL CONGRESS ON HIGH-SPEED PHOTOGRAPHY AND PHOTONICS   4948   425 - 430   2003年

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Hydrodynamic instability in laser-irradiated targets have been investigated in detail by using ultra high-speed x-ray radiographic technique. Recently developed high-resolution x-ray imaging for laser-driven Rayleigh-Taylor (RT) instability experiments as well as data including RT growth rate, ablation density and plasma density profile are described. Results are of great importance for comprehensive understanding of the dispersion relation of the laser-driven RT instability. Especially, direct observation of the ablation density was first achieved with temporal and spatial resolutions of 100 ps and 3 mum, respectively. Imaging technique includes x-ray Moire imaging, x-ray penumbral imaging and Fresnel phase zone plate imaging coupled with x-ray streak cameras or x-ray CCD cameras. Experiments were performed by using Gekko-XII/HIPER laser system at the Institute of Laser Engineering, Osaka University.

Hydrodynamic instability experiments on the HIPER laser 査読

K Shigemori, H Azechi, S Fujioka, Y Kanai, N Miyanaga, A Murakami, T Muranaka, H Nagatomo, M Nakai, M Nishikino, K Nishihara, H Nishimura, T Sakaiya, H Shiraga, A Sunahara, H Takabe, T Takayama, Y Tamari, A Tanaka, T Yamanaka

PLASMA PHYSICS   669   269 - 272   2003年

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We present recent results on the hydrodynamic instability experiments on the HIPER (High Intensity Plasma Experimental Research) laser facility at Institute of Laser Engineering, Osaka University. We measured the Rayleigh-Taylor growth rate on the HIPER laser. Also measured were all parameters that determine the RT growth rate. We focused on the measurements of the ablation density of laser-irradiated targets, which had not been experimentally measured. The experimental results were compared with calculations with one dimensional simulation coupled with and without Fokker-Planck equation for electron heat transport.

Progress in understanding of laser-produced plasmas for EUV source 査読

N Miyanaga, K Fujima, S Fujioka, Y Fujimoto, H Fujita, H Furukawa, K Hashimoto, T Hibino, T Kagawa, T Kato, T Kawamura, F Koike, R Matsui, R More, M Murakami, K Nagai, M Nakai, M Nakatsuka, T Nishikawa, K Nishihara, H Nishimura, T Norimatsu, T Okuno, A Sasaki, K Shigemori, Y Shimada, FL Sohnatzadeh, A Sunahara, H Tanuma, Y Tao, K Tsubakimoto, S Uchida, M Yamaura, H Yoshida, Zhakhovskii, V, Y Izawa

2003 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2   297 - 298   2003年

Study on EUV emission properties of laser-produced plasma at ILE, Osaka 査読

M Nakai, H Nishimura, K Shigemori, N Miyanaga, T Norimatsu, K Nagai, R Matsui, T Hibino, T Okuno, FS Sohbatzadeh, Y Tao, K Hashimoto, M Yamaura, S Fujioka, H Nagatomo, Zhakhovckii, V, K Nishihra, S Uchida, Y Shimada, H Furukawa, M Nakatsuka, Y Izawa

LASER-GENERATED AND OTHER LABORATORY X-RAY AND EUV SOURCES, OPTICS, AND APPLICATIONS   5196   289 - 297   2003年

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A new research project on extreme ultraviolet (EUV) source development has just been started at the Institute of Laser Engineering, Osaka University. The main task of this project is to find a scientific basis for generating efficient, high-quality, high power EUV plasma source for semiconductor industry. A set of experimental data is to be provided to develop a detailed atomic model included in computer code through experiments using GEKKO-XII high power laser and smaller but high-repetitive lasers. Optimum conditions for efficient EUV generation will be investigated by changing properties of lasers and targets. As the,first step of the experiments, spherical solid tin and tin-oxide. targets were illuminated uniformly with twelve beams from the GEKKO XII. It has been confirmed that maximum conversion efficiency into 13.5 nm EUV light is achieved at illumination intensity less than 2 x 10(11) W/cm(2). No significant difference is found between laser wavelengths of one pm and a half mum. Density structure of the laser-irradiated surface of a planar tin target has been measured experimentally at 10(12) W/cm(2) to show formation of double ablation structure with density plateau by thermal radiation transport. An opacity experiment has just been initiated.

Nuclear fusion - Fast heating scalable to laser fusion ignition 査読

R Kodama, H Shiraga, K Shigemori, Y Toyama, S Fujioka, H Azechi, H Fujita, H Habara, T Hall, Y Izawa, T Jitsuno, Y Kitagawa, KM Krushelnick, KL Lancaster, K Mima, K Nagai, M Nakai, H Nishimura, T Norimatsu, PA Norreys, S Sakabe, KA Tanaka, A Youssef, M Zepf

NATURE   418 ( 6901 )   933 - 934   2002年8月

Penumbral imaging for measurement of the ablation density in laser-driven targets 査読

S Fujioka, H Shiraga, M Nishikino, M Heya, K Shigemori, M Nakai, H Azechi, S Nakai, T Yamanaka

REVIEW OF SCIENTIFIC INSTRUMENTS   73 ( 7 )   2588 - 2596   2002年7月

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One-dimensional (1D) penumbral imaging technique with high spatial resolution has been developed, and applied to density profile measurements in laser-driven Rayleigh-Taylor instability experiments at a GEKKO XII-HIPER laser system. A laser-irradiated planar target was observed with side-on x-ray backlighting. A penumbral image of an x-ray radiograph was made by using a knife-edge imager. The x-ray radiograph was, then, reconstructed by differentiating the penumbral image with a proper Wiener filtering. A density profile was deduced from the reconstructed x-ray radiograph. In a proof-of-principle experiment, the density profile of a polystyrene (PS) target before laser irradiation was measured by using this method, and high spatial resolution of 3-4 mum was demonstrated. A laser-irradiated PS target in the acceleration phase was observed. The experimentally observed density profile was found to be consistent with the prediction by a 1D hydrodynamic simulation code. The x-ray penumbral imaging is a very simple and useful technique with high spatial resolution for research in hydrodynamics relevant to inertial fusion energy. (C) 2002 American Institute of Physics.