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Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Nishikawa, Takeshi*
Proceedings of SPIE, Vol.9776, p.97762C_1 - 97762C_6, 2016/03
Times Cited Count：1 Percentile：51.18(Optics)For the improvement of efficiency and output of the laser pumped plasma (LPP) extreme ultra-violet (EUV) light source, we present a hydrodynamics model of laser irradiated Sn targets. The model takes liquid/solid to gas transition and mixed phase condition of the flow into account for the calculation of the distribution of the particles produced by the pre-pulse laser irradiation and optimization of the EUV source. Firstly, we investigate the mechanisms of the fragmentation of the target and particle emission, including the effect of the equation of state of Sn, and secondly, an applicable model is proposed based on the analysis.
Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; Hirose, Ryoichi*; et al.
Applied Physics Letters, 106(12), p.121109_1 - 121109_5, 2015/03
Times Cited Count：15 Percentile：50.09(Physics, Applied)Arita, Ren*; Nakazato, Tomoharu*; Shimizu, Toshihiko*; Yamanoi, Kohei*; Empizo, M.*; Hori, Tatsuhiro*; Fukuda, Kazuhito*; Minami, Yuki*; Sarukura, Nobuhiko*; Maruyama, Momoko; et al.
Optical Materials, 36(12), p.2012 - 2015, 2014/10
Times Cited Count：10 Percentile：47.42(Materials Science, Multidisciplinary)A single shot image of a ZnO crystal excited by the EUV laser of Kansai Photon Science Institute was captured. The evaluated EUV beam waist radii from the ZnO emission pattern along the horizontal and vertical axes are 5.0 and 4.7
m, respectively. The expected focal spot size of EUV laser and the spatial resolution of the magnifier (including the Schwarzschild objectives and lenses) are however 1 and 4m, respectively. The discrepancy on the spatial resolutions is attributed to exciton diffusion. We estimated the ZnO exciton diffusion length from the effective decay time which is shortened by exciton-exciton collision quenching and which is dependence on excitation energy density. Our results indicate that the short lifetime of ZnO is required to improve the spatial resolution.
Fujioka, Shinsuke*; Nishimura, Hiroaki*; Nishihara, Katsunobu*; Sasaki, Akira; Sunahara, Atsushi*; Okuno, Tomoharu*; Ueda, Nobuyoshi*; Ando, Tsuyoshi*; Tao, Y.*; Shimada, Yoshinori*; et al.
Physical Review Letters, 95(23), p.235004_1 - 235004_4, 2005/12
Times Cited Count：155 Percentile：95.57(Physics, Multidisciplinary)no abstracts in English
Masnavi, M.*; Nakajima, Mitsuo*; Sasaki, Akira; Hotta, Eiki*; Horioka, Kazuhiko*
Applied Physics Letters, 87(11), p.111502_1 - 111502_3, 2005/09
Times Cited Count：4 Percentile：17.60(Physics, Applied)no abstracts in English
Shimada, Yoshinori*; Nishimura, Hiroaki*; Nakai, Mitsuo*; Hashimoto, Kazuhisa*; Yamaura, Michiteru*; Tao, Y.*; Shigemori, Keisuke*; Okuno, Tomoharu*; Nishihara, Katsunobu*; Kawamura, Toru*; et al.
Applied Physics Letters, 86(5), p.051501_1 - 051501_3, 2005/01
Times Cited Count：115 Percentile：94.17(Physics, Applied)no abstracts in English
Sasaki, Akira; Nishihara, Katsunobu*; Murakami, Masakatsu*; Koike, Fumihiro*; Kagawa, Takashi*; Nishikawa, Takeshi*; Fujima, Kazumi*; Kawamura, Toru*; Furukawa, Hiroyuki*
Applied Physics Letters, 85(24), p.5857 - 5859, 2004/12
Times Cited Count：43 Percentile：79.57(Physics, Applied)no abstracts in English
Masnavi, M.*; Nakajima, Mitsuo*; Sasaki, Akira; Hotta, Eiki*; Horioka, Kazuhiko*
Japanese Journal of Applied Physics, 43(12), p.8285 - 8291, 2004/12
Times Cited Count：5 Percentile：23.64(Physics, Applied)no abstracts in English
Nishihara, Katsunobu*; Nishimura, Hiroaki*; Mochizuki, Takayasu*; Sasaki, Akira
Reza Kenkyu, 32(5), p.330 - 336, 2004/05
no abstracts in English
Fujima, Kazumi*; Nishihara, Katsunobu*; Kawamura, Toru*; Furukawa, Hiroyuki*; Kagawa, Takashi*; Koike, Fumihiro*; More, R.*; Murakami, Masakatsu*; Nishikawa, Takeshi*; Sasaki, Akira; et al.
Emerging Lithographic Technologies VIII, Proceedings of SPIE Vol.5374, p.405 - 412, 2004/00
no abstracts in English
Sasaki, Akira
Purazuma, Kaku Yugo Gakkai-Shi, 79(4), p.315 - 317, 2003/04
no abstracts in English
Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*
no journal, ,
no abstracts in English
Sasaki, Akira
no journal, ,
Improvement of the efficiency and output power of the EUV source is essential for the realization of the next generation micro-lithography. Recently, a high efficiency is obtained using the double pulse technique, where the Sn droplet is broken up into particles by the irradiation of the relatively weak pre-pulse laser. For the optimization of the source, we study methods for the modeling of pre-plasma formation including the solid/liquid to gas phase transition of Sn and particle emission. We study the equation of state of Sn and phase transition theoretically, and also study methods to calculate distribution of solid/liquid and gas phase after the phase transition. Results of test calculation of the evaporation hot Sn droplet will be shown.
Sasaki, Akira
no journal, ,
Modeling of the fragmentation and particle emission from Sn droplet target, which is irradiated by the pre-pulse laser is developed for the optimization of the output and efficiency of the EUV source. Methods of reconstruction of the Lagrangian mesh to represent the shape and arrangement of particles for the hydrodynamics simulation are developed. The ratio of liquid and gas as well as the latent heat are determined by evaluating the Gibbs free energy in the material based on the Van-der-waals theory. Results of test calculation for the evaporating hot Sn droplet are presented.
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*
no journal, ,
For the development of laser plasma pumped (LPP) extreme ultraviolet light (EUV) source, we develop a new hydrodynamics model, which is applicable to the fragmentation of liquid Sn by the pre-pulse laser irradiation. A 2-dimensional Lagrange simulation code with mesh reorganization algorithms as well as phase transition dynamics is developed and initial application to an analysis of the particle formation during the evaporation of a hot Sn droplet is presented.
Sasaki, Akira; Murakami, Izumi*; Kato, Daiji*; Morita, Shigeru*
no journal, ,
The non-local thermodynamic equilibrium (nLTE) atomic kinetics in high-Z plasmas is investigated for Ag, Sn through W, which are used for X-ray lasers, EUV sources and fusion devices. We develop the atomic model based on nl configuration averaged levels structure, with atomic energy levels, radiative rates and autoionization rates calculated using the HULLAC code. The dielectronic recombination processes are included into the model by including autoionizing levels explicitly. We investigate the mean charge and radiative power loss with respect to the size of the model; by defining the groups of the levels, which consist of core a configuration and one excited electron, and by performing calculations increasing the number of groups. It is found that as a general trend, the mean charge decreases and the radiative power loss increases, until convergence is obtained when sufficiently large number of dielectronic recombination channels is included. The model is validated at code comparison workshops and also comparison with spectroscopic measurements, which are carried out using magnetic fusion devices.
Sasaki, Akira
no journal, ,
no abstracts in English
Sasaki, Akira
no journal, ,
no abstracts in English
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*
no journal, ,
no abstracts in English
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*
no journal, ,
no abstracts in English
