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C. Yamanaka,
S. Nakai,
T. Yamanaka, Y. Izawa,
Y. Kato,
K. Mima,
K. Nishihara,
T. Mochizuki,
M. Yamanaka,
M. Nakatsuka, [......],
K. Yoshida,
H. Azechi,
H. Nishimura,
T. Norimatsu,
S. Ido,
N. Miyanaga,
S. Sakabe,
H. Takabe,
J. Jitsuno,
M. Takagi
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ABSTRACT: High aspect ratio pellet targets are ablatively imploded with twelve green beams of GEKKO XII. Multiplexing of shock waves with a quasi-tailored pulse is performed successfully in DT fuel compression. The highest neutron yield achieved is 1.25 × 1012 per shot. The development of new diagnostics such as neutron activation and secondary fusion reaction diagnostics is also presented.
Nuclear Fusion 01/2011; 27(1):19. · 4.09 Impact Factor
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S Fujioka,
H Nishimura,
H Takabe,
N Yamamoto,
K Nishihara,
D Salzmann,
T Norimatsu,
N Miyanaga,
K Mima,
H Azechi, [......],
J Zhong,
G Zhao,
Y Li,
Q Dong,
S Wang,
Y Zhang,
J Zhang,
Y-J Rhee,
Y-W Lee,
D-H Kwon
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ABSTRACT: Laser produced plasma is one of the brilliant x-ray source that has unique capabilities for use in a wide range of science. Here we describe two examples of laser-produced plasma x-ray source application; one is for the semiconductor device industry and the other is for the astronomy. Extreme ultraviolet (EUV) light sources for microlithography are receiving much attention as an industrial application of laser-produced x-ray source. High power and clean EUV light source, 13.5 nm of wavelength, is developed for mass-production of next generation semiconductor devices. Highest EUV conversion efficiency of 4% has been attained by using low-density and minimum-mass tin targets produced by laser-driven explosion of micro-droplet. In addition, it was recently demonstrated that laser-produced x-ray source is very useful to simulate x-ray astronomical phenomena in the laboratory. A 0.5-keV Planckian x-ray source was created with laser driven implosion for producing non-local-thermodynamical-equilibrium (non-LTE) photoionized plasmas, which is a key to understand astronomical compact objects. Laboratory experiment of non-LTE photoionized plasma offers novel test bed for validation and verification of computational codes used in x-ray astronomy.
Journal of Physics Conference Series 09/2010; 244(1):012001.
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ABSTRACT: In the chemical process, it is hard to describe the polymer property by a rigorous model based on the physical and chemical theory. The soft sensor with the statistical data processing is often used for modeling to monitor and to control the polymer quality. We confirmed regarding the estimation accuracy that using data from the on-line tracking simulator is better than using data from the conventional use of the soft sensor. The on-line tracking simulator perfectly simulates the target and provides the virtual input data which can not be measured by the soft sensor on the real time. We propose the application of the rigorous and the statistical model to the plant operation.
ICCAS-SICE, 2009; 09/2009
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ABSTRACT: This paper deals with a lithium/tin combined target to increase the conversion efficiency of extreme ultraviolet (EUV) of 13.5 nm emission from laser-produced plasma. The bilayer target of glass/lithium (20 nm)/tin (50 nm) exhibits a sharp and strong emission in comparison with a Sn bulk target. The reverse coating of glass/tin/lithium was unstable and EUV could not be observed. By using nano-porous SnO2 and an electrochemical deposition of lithium, nano-structured lithium/tin composite was prepared, and was stable without deliquescence of lithium.
Laser and Particle Beams 08/2008; 26(03):497 - 501. · 1.62 Impact Factor
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S. Namba,
S. Fujioka,
H. Sakaguchi,
H. Nishimura,
Y. Yasuda,
K. Nagai,
N. Miyanaga, Y. Izawa,
K. Mima,
K. Sato,
K. Takiyama
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ABSTRACT: Out-of-band (OOB) radiation, in contrast to the in-band radiation at 13.5 nm in a 2% bandwidth, emitted from dense tin plasmas generated by a laser was investigated for application as an extreme ultraviolet lithography light source. It was found that the continuum spectrum, which overwhelms the atomic and ionic line emissions, is responsible for the intense OOB radiation. The spectral distribution of the continuum emission matches that of blackbody radiation with a temperature of about 10 eV. The OOB radiation can be considerably suppressed by employing a minimum-mass target and short-pulse laser irradiation. Spectroscopic observations were made to examine the spatiotemporal behavior of the plasma immediately after laser irradiation. Prominent line broadening due to the Stark effect in the high-density plasma was observed, from which the variation of the electron density was deduced. The electron density and temperature on the target surface were 10<sup>17</sup>–10<sup>18</sup> cm <sup>-3</sup> and a few eV’s, respectively, in the first 200 ns after laser illumination. In addition, the expansion velocities of neutral and singly ionized tin atoms were deduced from time-of-flight transients in the spectral emission.
Journal of Applied Physics 08/2008; · 2.17 Impact Factor
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ABSTRACT: Minimum-mass target is an effective way to control debris produced during 13.5 nm EUV emission. In this work, we introduce a new method to fabricate 500 μm PVA air bubbles which is the supporting medium for tin layer using our home-made apparatus. We found that the thinner needle could produce smaller PVA bubbles at a stirring speed of > 420 rpm and the air bubbles were found to be stable more than 40 min which satisfies the requirement of EUV target. Tin elements were assembled on the PVA air bubbles and the presence of tin was confirmed by ICP experiment. The stability of the PVA air bubbles shows that they could be used as EUV emission target in the future.
Journal of Physics Conference Series 06/2008; 112(3):032065.
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Y Izawa,
K Nishihara,
H Tanuma,
A Sasaki,
M Murakami,
A Sunahara,
H Nishimura,
S Fujioka,
T Aota,
Y Shimada,
M Yamaura,
M Nakatsuka,
H Fujita,
K Tsubakimoto,
H Yoshida,
N Miyanaga,
K Mima
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ABSTRACT: In the development of a high power EUV source used in the EUV lithography system, it is important to understand basic physics of EUV plasma and to optimize laser and target conditions. We have been constructed EUV database of laser-produced tin plasma by the theoretical and experimental studies. On the basis of our understanding, the optimum conditions of lasers and plasmas were clarified, and we proposed the guidelines of laser plasma to obtain clean, efficient and high power EUV source for the practical EUV lithography system. In parallel to such studies, novel targets and high power laser system to generate the optimized EUV source plasma have been developed. Recent progresses of our program are presented.
Journal of Physics Conference Series 06/2008; 112(4):042047.
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S Fujioka,
H Nishimura,
M Shimomura,
H Sakaguchi,
Y Nakai,
T Aota,
Y Shimada,
A Sunahara,
K Nishihara,
N Miyanaga, Y Izawa,
K Mima
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ABSTRACT: The optimum plasma conditions of extreme ultraviolet (EUV) light source for lithography were experimentally clarified that is optically thin and minimum mass Sn plasma generated from a limited size target. Sn plasma is quite opaque for EUV light of 13.5 nm in wavelength, therefore 13.5 nm light emitted from deep within a Sn plasma is strongly absorbed, thus optically thin plasma production is essential for efficient EUV generation. Contamination of EUV optics caused by debris emanated from laser irradiated Sn targets is a serious problem in the Sn based EUV source system. Target residue around the laser spot is the dominant source of neutral debris, which can be reduced with supplying the minimum mass target containing the minimum number of Sn atoms required for sufficient EUV generation. Spectral purity of generated EUV light is an important requirement to expose clear mask image on a photo-resist film without chromatism. Out-of-band radiation in the vacuum ultraviolet range is dominantly radiated from the laser spot peripheral. Target size must be equal to the laser spot size to suppress the out-of-band radiation.
Journal of Physics Conference Series 06/2008; 112(4):042049.
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ABSTRACT: EUV emission from spherical and planer targets were precisely characterized as an experimental database for use in EUV source generation at high repetition rates. In the single-shot base experiments, conversion efficiency as high as those for the plasma geometry has been demonstrated. The integrated experiment was made with 10 Hz plasma generation, obtained conversion efficiency is low mainly due to unstable positioning of the droplets.
Journal of Physics Conference Series 06/2008; 112(4):042064.
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ABSTRACT: Wavefront correction until Zernike polynomial of degree three by a phase conjugate plate has been demonstrated in a high-energy Nd:YLF amplifier system. 108, amplification of 380 mJ has been achieved with a near-diffraction-limited beam quality.
Journal of Physics Conference Series 06/2008; 112(3):032060.
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ABSTRACT: We have developed a novel debris-free in-air laser dicing technology, which gives more design freedoms in the structure, process and materials of MEMS as well as improves yields. Our technology combines two processes: dicing guide fabrication and wafer separation process. The first process is the internal transformation using a fundamental wavelength of a Ti: Sapphire laser or a Nd:YAG laser. The second process is non-contact separation by thermally-induced crack propagation using a CO<sub>2</sub> laser or mechanical separation by bending stress. The internal transformation fabricated in the first process worked well as the guide of separation, and the processed wafer was diced with low stress. The diced lines completely followed the internal transformation.
Micro Electro Mechanical Systems, 2008. MEMS 2008. IEEE 21st International Conference on; 02/2008
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Y Kato,
T Mochizuki,
M Nakatsuka,
T Yamanaka,
K loshida, Y Izawa,
K Mima,
K Fujita,
H Daido,
M Inoue,
S Nakai,
C Yamanaka
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ABSTRACT: A description is given of the construction of laser systems (drivers) with neodymium glass and CO2 gas active media designed for laser fusion research at the Institute of Laser Engineering at the Osaka University. The results are given of investigations of various physical processes in laser systems, such as the saturation effect in neodymium glass lasers and amplification of short light pulses in CO2 lasers.
Soviet Journal of Quantum Electronics 10/2007; 13(1):38.
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R. A. Snavely,
B. Zhang,
K. Akli,
Z. Chen,
R. R. Freeman,
P. Gu,
S. P. Hatchett,
D. Hey,
J. Hill,
M. H. Key, [......],
P. Patel,
R. Stephens,
M. Tampo,
K. A. Tanaka,
R. Town,
Y. Toyama,
T. Tsutsumi,
S. C. Wilks,
T. Yabuuchi,
J. Zheng
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ABSTRACT: The results of laser-driven proton beam focusing and heating with a high energy (170 J) short pulse are reported. Thin hemispherical aluminum shells are illuminated with the Gekko petawatt laser using 1 μm light at intensities of ∼ 3×1018 W/cm2 and measured heating of thin Al slabs. The heating pattern is inferred by imaging visible and extreme-ultraviolet light Planckian emission from the rear surface. When Al slabs 100 μm thick were placed at distances spanning the proton focus beam waist, the highest temperatures were produced at 0.94× the hemisphere radius beyond the equatorial plane. Isochoric heating temperatures reached 81 eV in 15 μm thick foils. The heating with a three-dimensional Monte Carlo model of proton transport with self-consistent heating and proton stopping in hot plasma was modeled.
Physics of Plasmas 09/2007; 14(9):092703-092703-5. · 2.15 Impact Factor
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H. Nishimura,
K. Nishihara,
S. Fujioka,
T. Aota,
T. Ando,
M. Shimomura,
K. Sakaguchi,
K. Nagai,
T. Norimatsu,
M. Murakami,
N. Miyanaga, Y. Izawa,
K. Mima,
Y. Simada,
M. Yamaura,
A. Sunahara,
A. Sasaki,
H. Tanuma,
F. Koike,
K. Fuijma
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ABSTRACT: Extreme ultraviolet (EUV) radiation from laser-produced plasma has been thoroughly studied for application in mass-production of the next generation semiconductor devices. Comprehensive experimental databases are provided for a wide range of parameters of lasers and targets. The atomic models are benchmarked with spectroscopic measurements not only for laser-produced plasma (LPP) but also for EUV emissions from magnetic-confinement plasmas or the charge exchange for uniquely ionized ions colliding with rare-gas targets. These experimental data are utilized in the industry as well as used to benchmark the radiation hydrodynamic code, including equation-of-state solvers and advanced atomic kinetic models, dedicated for EUV plasma predictions. Present status of the LPP EUV source studies is presented.
AIP Conference Proceedings 08/2007; 926(1).
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T. Kurita,
R. Yasuhara,
T Sekine,
T. Ikegawa,
T Kawashima,
O Matsumoto,
M Miyamoto,
H. Kan,
H Yoshida,
J. Kawanaka,
M Nakatsuka, Y Izawa,
T. Kanabe
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ABSTRACT: High power laser becomes a key component for the scientific and industry applications. Above all, diode-pumped solid state lasers (DPSSLs) play an important role in inertial fusion energy (IFE) and related high-energy applications as well as material processes. In these applications, repeatable operation (several Hz ~ 100 Hz) is indispensable. In this paper we present the diode-pumped zig-zag slab laser. Average power of 213 W (21.3 J at 10 Hz) was successfully achieved. The diffraction limited focusability was achieved by use of SBS phase conjugator. These results have indicated the 100-J scalability of slab architecture and the 1-kW average power potential of repeatable operation up to 10 Hz for high-energy applications.
Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on; 07/2007
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Y. Inubushi,
H. Nishimura,
M. Ochiai,
S. Fujioka,
T. Johzaki,
K. Mima,
T. Kawamura,
S. Nakazaki,
T. Kai,
S. Sakabe, Y. Izawa
Journal of Quantitative Spectroscopy and Radiative Transfer 08/2006; 101:191-192. · 3.19 Impact Factor
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Y. Tao,
H. Nishimura,
T. Okuno,
S. Fujioka,
N. Ueda,
M. Nakai,
K. Nagai,
T. Norimatsu,
N. Miyanaga,
K. Nishihara, Y. Izawa
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ABSTRACT: Temporally resolved imaging of 13.5 nm extreme ultraviolet (EUV) emission from laser-produced Sn plasmas was experimentally investigated with a monochromatic EUV imager. Absorption caused by the surrounding plasma was eliminated by adopting a stripe Sn target laminated on a plastic film so that the CH plasma tamped lateral expansion of the Sn plasma. The experimental results revealed that reabsorption induced by plasma, both in EUV emission-dominant and long scale coronal regions, plays an key role in extracting the EUV light from the plasma efficiently.
Applied Physics Letters 12/2005; 87(24):241502-241502-3. · 3.84 Impact Factor
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Keiji Nagai,
H. Azechi,
F. Ito,
A. Iwamoto, Y. Izawa,
T. Johzaki,
R. Kodama,
K. Mima,
T. Mito,
M. Nakai,
N. Nemoto,
T. Norimatsu,
Y. Ono,
K. Shigemori,
H. Shiraga,
K. A. Tanaka
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ABSTRACT: Development of foam materials for cryogenically cooled fuel targets is described in this paper. The fabrication development was initiated as a part of the fast ignition realization experiment (FIREX) project at the ILE, Osaka University under a bilateral collaboration between Osaka University and National Institute for Fusion Science (NIFS). For the first stage of FIREX (FIREX-I), a foam cryogenic target was designed in which low-density foam shells with a conical light guide will be fuelled through a narrow pipe and will be cooled down to the cryogenic temperature. Acrylic polymer, resorcinol–formaldehyde (RF) resin, poly(4-methyl-1-pentene) (PMP), and polystyrene-based crosslinking polymer have been investigated as supporting materials for cryogenic fuel. The properties of the material and the present status of the material development are summarized.
Nuclear Fusion 10/2005; 45(11):1277. · 4.09 Impact Factor
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H Fujita,
M Nakatsuka,
Tao Wang,
K. Tsubakimoto,
Y Fujimoto,
H Yoshida,
N Miyanaga, Y Izawa,
S Matsuoka,
H. Kubomura,
T Kasamatsu,
T Uchiyama,
H Miyajima,
Hirofumi Kan
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ABSTRACT: We have been developing a high repetition (5 kHz) and high power (5 kW) Nd: YAG laser system pumped by cw LDs for EUV lithography. Design concepts and experimental results will be reported.
Lasers and Electro-Optics, 2005. CLEO/Pacific Rim 2005. Pacific Rim Conference on; 09/2005
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ABSTRACT: An active-mirror oscillator with a cryogenically cooled Yb: YLF has been demonstrated for the first time. Output pulse energy was 40mJ and 3.4mJ for the free-running and Q-switching modes, respectively, in quasi-cw pump at 10Hz.
Lasers and Electro-Optics, 2005. CLEO/Pacific Rim 2005. Pacific Rim Conference on; 09/2005
