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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:52.57(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.
Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*
Plasma and Fusion Research (Internet), 6(Sp.1), p.2401145_1 - 2401145_4, 2011/12
Atomic processes and radiation from multiple charged ions in plasmas are of the interest in the investigation of plasma wall interaction and transport of impurity ions in the fusion devices. The emission from multiple charged ions is also investigated for the development of extreme ultra violet light (EUVL) sources at . Efficient emission through the 4d-4f + 4p-4d transition array is obtained from tin ions. An optimization of pumping conditions of laser produced plasma sources is carried out theoretically and experimentally. We also investigate an extension of the plasma light sources to short wavelength to using Gd and Tb plasmas. We discuss requirements to the atomic structure, rate coefficient and collisional radiative codes to determine ion abundance and level population as a function of plasma temperature and density, to calculate the radiation intensity as well as emission spectrum.
Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*
Applied Physics Letters, 97(23), p.231501_1 - 231501_3, 2010/12
Times Cited Count:15 Percentile:52.44(Physics, Applied)Emission spectrum and conversion efficiency of laser produced terbium plasmas are investigated theoretically on the basis of computational atomic data. It is shown that calculation reproduces the main peak of the experimental spectrum at nm, which originates from 4-4 transitions of near palladium like ions (Tb). Simple model of the isothermal expansion of plasma suggests that efficient emission can be obtained by pumping a plasma with a laser pulse with an intensity approximately one order of magnitude grater than in the case of tin sources at nm.
Sasaki, Akira; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishihara, Katsunobu*; Fujioka, Shinsuke*; Nishikawa, Takeshi*; Koike, Fumihiro*; Ohashi, Hayato*; Tanuma, Hajime*
Journal of Applied Physics, 107(11), p.113303_1 - 113303_11, 2010/06
Times Cited Count:45 Percentile:82.61(Physics, Applied)Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. An atomic model of Sn is developed on the basis of calculated atomic data using the Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions are identified. The wavelengths of the 4-4 + 4-4 transitions of Sn to Sn are investigated. Results of calculation are compared with those of the charge exchange spectroscopy, measurement of the emission spectrum of the laser produced plasma EUV source, and the opacity measurement of a radiatively heated Sn sample. A reasonable agreement is observed between calculated and experimental EUV emission spectra. The spectral emissivity and opacity of Sn plasmas are calculated using a full collisional radiative (CR) model as a function of electron temperature and ion density.
Sasaki, Akira; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*
High Energy Density Physics, 5(3), p.147 - 151, 2009/09
Times Cited Count:11 Percentile:39.57(Physics, Fluids & Plasmas)We study the radiative properties of the EUV source to address conditions to achieve an output power and efficiency required for its application to the next generation microlithography. An atomic model is developed based on the atomic data calculated by Hullac code, which is validated through detailed comparisons with experimental emission and a absorption spectra. The atomic model is improved with respect to the wavelength of the strong emission lines, and the number of satellite channels taken into account. As a result, the radiation hydrodynamics model is shown to successfully reproduce the experiments. We show Sn plasma is more efficient than Xe plasma because of the atomic number dependence of the emission wavelength, and the use of CO lasers as a pumping source has an advantage to reduce satellite contribution and to have narrower emission spectrum to obtain higher conversion efficiency.
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*
Journal of Physics; Conference Series, 163, p.012107_1 - 012107_4, 2009/06
Times Cited Count:5 Percentile:84.68(Physics, Multidisciplinary)no abstracts in English
Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*
Alternative Lithographic Technologies (Proceedings of SPIE Vol.7271), p.727130_1 - 727130_8, 2009/03
We investigate characteristic feature of the atomic radiation from tin plasmas, which allow one to obtain high power EUV emission efficiently. We develop a collisional radiative model of tin ions to calculate steady-state and time dependent ion abundance, level population, and coefficients of radiative transfer of the plasma. The model, which is based atomic data calculated using the Hullac code is refined both theoretically and experimentally. Calculation of the spectral emissivity and opacity are carried out over a wide range of plasma density and temperature, and pumping conditions to obtain high conversion efficiency are discussed.
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*
Reza Kenkyu, 36(Suppl.), p.1132 - 1135, 2008/11
no abstracts in English
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*
Journal of Physics; Conference Series, 112, p.042062_1 - 042062_4, 2008/00
Times Cited Count:5 Percentile:87.55(Physics, Fluids & Plasmas)no abstracts in English
Nishihara, Katsunobu*; Sunahara, Atsushi*; Sasaki, Akira; Nunami, Masanori*; Tanuma, Hajime*; Fujioka, Shinsuke*; Shimada, Yoshinori*; Fujima, Kazumi*; Furukawa, Hiroyuki*; Kato, Takako*; et al.
Physics of Plasmas, 15(5), p.056708_1 - 056708_11, 2008/00
Times Cited Count:122 Percentile:97.42(Physics, Fluids & Plasmas)Sunahara, Atsushi*; Sasaki, Akira; Tanuma, Hajime*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Fujioka, Shinsuke*; Aota, Tatsuya*; Yamaura, Michiteru*; Shimada, Yoshinori*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 83(11), p.920 - 926, 2007/11
We study the EUV emission from laser produced Sn plasmas using the 1D and 2D radiation hydrodynamics simulation, for the development of EUV source for the next generation semiconductor lithography. The opacity and emissivity of the plasma used in the simulation are calculated by a detailed atomic model, with the accurate wavelength of emission lines obtained from the detailed spectroscopic measurements. Calculation is shown to reproduce the experimental spectrum and conversion efficiency reasonably, including the effect of photo pumping which modifies the EUV emission spectrum in the case with a long scale length of the plasmas.
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Fujima, Kazumi*; Kagawa, Takashi*; Koike, Fumihiro*; Tanuma, Hajime*
High Energy Density Physics, 3(1-2), p.250 - 255, 2007/05
Times Cited Count:17 Percentile:51.42(Physics, Fluids & Plasmas)no abstracts in English
Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Nishikawa, Takeshi*; Koike, Fumihiro*; Kagawa, Takashi*; Tanuma, Hajime*
Proceedings of SPIE's International Symposium on Microlithography, Vol.6151, p.61513W_1 - 61513W_8, 2006/03
The atomic processes in the Xe and Sn plasmas are investigated. The wavelength of atomic transitions is shown to have a critical effect in reproducing experiments. The wavelengths of resonance lines in our model are improved through detailed comparison with charge specific spectroscopic measurement. Distribution of satellite lines in the presence of the effect of the configuration interaction (CI) is investigated. The spectral profile of Xe and Sn emission, with determines fraction of usable EUV power, is discussed with respect to its dependence on the plasma temperature, density as well as the optical depth.
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:95.55(Physics, Multidisciplinary)no abstracts in English
Sakamoto, Yoshihiko; Kotake, Shoji; Nishikawa, Akira; Enuma, Yasuhiro; Ando, Masato; Sagayama, Yutaka
Proceedings of 13th International Conference on Nuclear Engineering (ICONE-13), 0 Pages, 2005/05
The Feasibility Study on Commercialized Fast Reactor (FR) Cycle Systems is under way in order to propose prominent FR cycle systems that will respond to the diverse needs of society in the future. The design studies on various FR system concepts have been achieved and then the evaluations of potential to achieve the development targets have been carried out. Crucial issues have been found out for each FR system concept and their development plans for the key technologies are summarized as the roadmap. The characteristics and the differences in performances have been investigated. The crucial issues and the development periods have been clarified. Further investigation is now in progress. The promising concept will be proposed based on result of comparative evaluation at the end of the Phase II study.
Kotake, Shoji; Sakamoto, Yoshihiko; Enuma, Yasuhiro; Ando, Masato; Nishikawa, Akira; Sagayama, Yutaka
Proceedings of 2005 International Congress on Advances in Nuclear Power Plants (ICAPP '05), 0 Pages, 2005/05
The Feasibility Study on Commercialized Fast Reactor (FR) Cycle Systems is under way in order to propose prominent FR cycle systems that will respond to the diverse needs of society in the future. The design studies on various FR system concepts have been achieved and then the evaluations of potential to achieve the development targets have been carried out. Crucial issues have been found out for each FR system concept and their development plans for the key technologies are summarized as the roadmap. The characteristics and the differences in performances have been investigated. The crucial issues and the development periods have been clarified. Further investigation is now in progress. The promising concept will be proposed based on result of comparative evaluation at the end of the Phase II study.
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:94.29(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:79.93(Physics, Applied)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
Sakamoto, Yoshihiko; Sakamoto, Yoshihiko; Enuma, Yasuhiro; Ando, Masato; Nishikawa, Akira; Kotake, Shoji; Ieda, Yoshiaki
Dai-14-Kai Kantaiheiyo Genshiryoku Kaigi (2004-Nen 3-Gatsu 21-Nichi25-Nichi), 0 Pages, 2003/00
This paper describes the summary of an interim report of phase II of the Feasibility Study on Commercialized FR Cycle Systems, related to reactor systems. Promising plant concepts (sodium-, lead-bismuth-, helium-, and water-cooled fast reactor) and reactor core concepts are presented. These concepts are quantitatively evaluated from the viewpoint of the suitability to the development targets, such as economic competitiveness, efficient utilization of resources and reduction of environmental burden, with securing safety. As results, sodium cooled fast reactor is well suited to the development targets. LBE cooled fast rector would have a potential to attain the development targets. Helium gas cooled fast reactor would have the great potential for high thermal efficiency and multipurpose energy system. And water cooled fast reactor has the advantage that there are many experiences with LWR. Furthermore the crucial issues for technical feasibility are also clarified as road map of key technology development for each concept.