Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
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：52.91(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：10 Percentile：38.07(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：9 Percentile：45.71(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：147 Percentile：95.58(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：17.87(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：113 Percentile：94.26(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：80.02(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：23.97(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; Sunahara, Atsushi*; Nishihara, Katsunobu*
no journal, ,
no abstracts in English
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; Nishihara, Katsunobu*; Sunahara, Atsushi*
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
Sasaki, Akira
no journal, ,
In the study of extreme ultraviolet (EUV) light sources, high conversion efficiency is achieved using the double pulse technique; a small tin droplet target is irradiated by the prepulse laser to cause fragmentation of the target to form a cloud small particles or mist, which is heated by the main CO
laser pulse to produce the uniform plasma from which efficient EUV emission is obtained. The fragmentation may be caused due to shock heating driven by the prepulse laser irradiation, which also may bring the target to the warm dense state. In this paper, a new hydrodynamics simulation, which will be used to calculate the temporal and spatial development of tin particles, is proposed. The simulation is based on the two dimensional self-adapting Lagrangian grid. The theory of liquid and gas phase transition in thermodynamic equilibrium, allows one to determine the ratio between gas and liquid phase at given temperature and density.
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*
no journal, ,
no abstracts in English
