Updated on 2024/03/14

写真a

 
NISHIKAWA Takeshi
 
Organization
Faculty of Environmental, Life, Natural Science and Technology Assistant Professor
Position
Assistant Professor
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Degree

  • Ph.D ( Osaka University )

  • Master of Engineering ( Osaka University )

Research Areas

  • Energy Engineering / Applied plasma science

  • Natural Science / Mathematical physics and fundamental theory of condensed matter physics

  • Energy Engineering / Fundamental plasma

Education

  • Osaka University   大学院工学研究科   電気工学専攻

    - 1992

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  • Osaka University   工学部   電気工学科

    - 1989

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Professional Memberships

Committee Memberships

  • プラズマ・核融合学会   代議員  

    2000   

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    Committee type:Academic society

    プラズマ・核融合学会

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  • 日本物理学会   原子・分子分科世話人  

    1998   

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    Committee type:Academic society

    日本物理学会

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Papers

  • N‐DMBI Doping of Carbon Nanotube Yarns for Achieving High n‐Type Thermoelectric Power Factor and Figure of Merit

    Hiroo Suzuki, Jun Kametaka, Shinya Nakahori, Yuichiro Tanaka, Mizuki Iwahara, Haolu Lin, Sergei Manzhos, Aung Ko Ko Kyaw, Takeshi Nishikawa, Yasuhiko Hayashi

    Small Methods   2024.3

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    Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    Abstract

    The application of carbon nanotube (CNT) yarns as thermoelectric materials for harvesting energy from low‐grade waste heat including that generated by the human body, is attracting considerable attention. However, the lack of efficient n‐type CNT yarns hinders their practical implementation in thermoelectric devices. This study reports efficient n‐doping of CNT yarns, employing 4‐(1, 3‐dimethyl‐2, 3‐dihydro‐1H‐benzimidazole‐2‐yl) phenyl) dimethylamine (N‐DMBI) in alternative to conventional n‐dopants, with o‐dichlorobenzene emerging as the optimal solvent. The small molecular size of N‐DMBI enables highly efficient doping within a remarkably short duration (10 s) while ensuring prolonged stability in air and at high temperature (150 °C). Furthermore, Joule annealing of the yarns significantly improves the n‐doping efficiency. Consequently, thermoelectric power factors (PFs) of 2800, 2390, and 1534 µW m−1 K−2 are achieved at 200, 150, and 30 °C, respectively. The intercalation of N‐DMBI molecules significantly suppresses the thermal conductivity, resulting in the high figure of merit (ZT) of 1.69×10−2 at 100 °C. Additionally, a π‐type thermoelectric module is successfully demonstrated incorporating both p‐ and n‐doped CNT yarns. This study offers an efficient doping strategy for achieving CNT yarns with high thermoelectric performance, contributing to the realization of lightweight and mechanically flexible CNT‐based thermoelectric devices.

    DOI: 10.1002/smtd.202301387

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  • Benzophenone: A Small Molecule Additive for Enhanced Performance and Stability of Inverted Perovskite Solar Cells. International journal

    Hytham Elbohy, Hiroo Suzuki, Takeshi Nishikawa, Thiri Htun, Kosei Tsutsumi, Chiyu Nakano, Aung Ko Ko Kyaw, Yasuhiko Hayashi

    ACS applied materials & interfaces   2023.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    In this study, we investigated the impact of benzophenone (BP), a small molecule additive, on the performance and stability of inverted perovskite solar cells (PSCs). Specifically, we introduced BP into the perovskite precursor solution of FAPbI3 to fabricate PSCs with an ITO/PEDOT:PSS/BP:FAPbI3/PCBM/C60/PCB/Ag architecture. The incorporation of BP with an optimum concentration of 2 mg mL-1 significantly enhanced the power conversion efficiency (PCE) of the inverted PSC from 13.12 to 18.84% with negligible hysteresis. Notably, the BP-based PSCs retained ∼90% of their initial PCE after being stored in ambient air with 30% relative humidity at 25 °C for 700 h. In contrast, control devices showed rapid degradation, retaining only 30% of their initial value within 300 h under the same conditions. We attributed the superior performance and stability of the BP-based PSCs to the grain boundary passivation of the perovskite film. The improvement was mainly attributed to the intermolecular interaction between the O-donor Lewis base BP material and both Pb2+ and FA+ in FAPbI3. This effectively suppresses trap-assisted recombination and promotes the conversion of the δ-phase to photoactive and stable α-phase FAPbI3. Overall, our findings suggest that BP is a promising additive for improving the performance and stability of inverted PSCs.

    DOI: 10.1021/acsami.3c09835

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  • Dispersion stability of tin(IV) oxide nanoparticles in polar solvents and water aided by ultrasonication

    Chinkhai Ong, Wengnam Lee, Linghong Lim, Wuyi Chong, Jingwen Chew, Yasuhiko Hayashi, Takeshi Nishikawa, Patrik Öhberg, Harith Ahmad, Yuenkiat Yap

    Japanese Journal of Applied Physics   62 ( 3 )   035002 - 035002   2023.3

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    Publishing type:Research paper (scientific journal)   Publisher:IOP Publishing  

    Abstract

    Dispersion stability of tin(IV) oxide nanoparticles dispersed in N-Methy-2-Pyrrolidone (NMP), dimethylformamide (DMF) and distilled water assisted by ultrasonication was investigated, aiming to identify a suitable liquid medium to effectively disperse tin(IV) oxide for many useful applications. The dispersions’ stability was characterized using field emission scanning electron microscopy, ultraviolet–visible spectroscopy and Zeta potential. The results show that distilled water has the highest stability with optimum sonication of 1 h. NMP shows better stability and consistency than DMF at different sonication timings. Good agreement between ultraviolet–visible absorbance and Zeta potentials shows that both distilled water and NMP are good mediums to produce highly stable tin(V) oxide dispersion.

    DOI: 10.35848/1347-4065/acc0b5

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    Other Link: https://iopscience.iop.org/article/10.35848/1347-4065/acc0b5/pdf

  • Mixed-halide copper-based perovskite R2Cu(Cl/Br)(4) with different organic cations for reversible thermochromism

    Amr Elattar, Kosei Tsutsumi, Hiroo Suzuki, Takeshi Nishikawa, Aung Ko Ko Kyaw, Yasuhiko Hayashi

    NEW JOURNAL OF CHEMISTRY   46 ( 45 )   21737 - 21745   2022.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ROYAL SOC CHEMISTRY  

    Two-dimensional (2D) hybrid perovskites have exhibited multiple features owing to their multiple quantum well structure. Here, we show the synthesis and characterization of 2D mixed-halide Cu-based perovskite crystals, R2Cu(Cl/Br)(4), with three different alkyl chains, where R is methyl, butyl, or hexyl ammonium cations. Exfoliated perovskite flakes exhibit reversible thermochromism with changes in color darkness with temperature variation. Differential scanning calorimetry and temperature-dependent X-ray diffraction measurements reveal that the thermochromic behavior mechanism of R2Cu(Cl/Br)(4) depends on the nature of the alkyl chain.

    DOI: 10.1039/d2nj04693h

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  • Enhancement of the mechanical and thermal transport properties of carbon nanotube yarns by boundary structure modulation

    Ryo Shikata, Hiroo Suzuki, Yuta Hayashi, Taisuke Hasegawa, Yuho Shigeeda, Hirotaka Inoue, Wataru Yajima, Jun Kametaka, Mitsuaki Maetani, Yuichiro Tanaka, Takeshi Nishikawa, Satoshi Maeda, Yasuhiko Hayashi, Masaki Hada

    NANOTECHNOLOGY   33 ( 23 )   2022.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:IOP Publishing Ltd  

    Carbon nanotubes (CNTs) exhibit extremely high nanoscopic thermal/electrical transport and mechanical properties. However, the macroscopic properties of assembled CNTs are significantly lower than those of CNTs because of the boundary structure between the CNTs. Therefore, it is crucial to understand the relationship between the nanoscopic boundary structure in CNTs and the macroscopic properties of the assembled CNTs. Previous studies have shown that the nanoscopic phonon transport and macroscopic thermal transport in CNTs are improved by Joule annealing because of the improved boundary Van-der-Waals interactions between CNTs via the graphitization of amorphous carbon. In this study, we investigate the mechanical strength and thermal/electrical transport properties of CNT yarns with and without Joule annealing at various temperatures, analyzing the phenomena occurring at the boundaries of CNTs. The obtained experimental and theoretical results connect the nanoscopic boundary interaction of CNTs in CNT yarns and the macroscopic mechanical and transport properties of CNT yarns.

    DOI: 10.1088/1361-6528/ac57d5

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  • Single Crystals of Mixed-Cation Copper-Based Perovskite with Trimodal Bandgap Behavior

    Amr Elattar, Wenhui Li, Hiroo Suzuki, Takashi Kambe, Takeshi Nishikawa, Aung Ko Ko Kyaw, Yasuhiko Hayashi

    CHEMISTRY-A EUROPEAN JOURNAL   28 ( 26 )   2022.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:WILEY-V C H VERLAG GMBH  

    Two-dimensional (2D) hybrid perovskites with novel functionalities and structural diversity are a perfect platform for emerging optoelectronic devices such as photodetectors, light-emitting diodes, and solar cells. Here, we demonstrate that excess concentration of Cesium bromide (CsBr) is key to the formation of easily exfoliated 2D Cs2Cu(Cl/Br)(4) perovskite crystal. Furthermore, by employing this trick to 2D perovskite MA(2)Cu(Cl/Br)(4) (MA=methylammonium), we achieve a phase-pure easily exfoliated 2D mixed-cation (MA/Cs)(2)Cu(Cl/Br)(4) perovskite crystal, which exhibits reduced bandgap (1.53 eV) with ferromagnetic behavior and photovoltaic property. The resultant mixed-cation structured device reveals enhanced efficiency compared to all MA and all Cs counterparts. These findings demonstrate the importance of cation-engineering in developing innovative materials with novel properties.

    DOI: 10.1002/chem.202104316

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  • Modeling the wavelength of unresolved transition arrays in the extreme ultraviolet region from Sn to Hf ions by combining theoretical and experimental spectral data

    A. Sasaki, K. Fujii, I. Murakami, H. A. Sakaue, T. Nishikawa, H. Ohashi, N. Nakamura

    AIP ADVANCES   12 ( 2 )   2022.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AIP Publishing  

    This paper proposes a method to determine the wavelength of unresolved transition arrays (UTAs) in the extreme ultraviolet (EUV) wavelength region from Sn to Hf plasma by combining calculated and experimental data. Based on a computational analysis of the atomic structure, we show that the wavelength of UTAs can be explained using the screening theory by a simple quadratic formula using the effective core charge and the screening constant for 4d electrons as parameters. The results from the model were compared with experiments to reproduce the trend of the spectrum, which has a minimum wavelength with respect to the ion charge. The wavelength is shown to agree with experiment over Pd- to Sr-like ions by applying a small shift that was determined using the spectrum observed in the electron beam ion trap. The present model would allow us to calculate the opacity of Sn plasmas with much smaller computational time than using present large-scale collisional radiative models, with fewer energy levels and parameterized rate coefficients, which will be also useful to investigate the efficiency of the EUV light source.& nbsp;(c) 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

    DOI: 10.1063/5.0077130

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  • Highly Oriented Carbon Nanotube Supercapacitors

    Kohei Komatsubara, Hiroo Suzuki, Hirotaka Inoue, Misaki Kishibuchi, Shona Takahashi, Tatsuki Marui, Shigeyuki Umezawa, Tomohiro Nakagawa, Kyohei Nasu, Mitsuaki Maetani, Yuichiro Tanaka, Miyato Yamada, Takeshi Nishikawa, Yoshifumi Yamashita, Masaki Hada, Yasuhiko Hayashi

    ACS APPLIED NANO MATERIALS   5 ( 1 )   1521 - 1532   2022.1

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    The demand for supercapacitors (SCs) with high capacitance, high charge-discharge rate, and long lifespan has been increasing because of the rapid development of wearable devices. In particular, flexible and durable SCs are essential for applications in wearable devices. A reasonable strategy to achieve such SCs involves the design and fabrication of SCs with flexible materials. In this study, we present a flexible SC with highly oriented carbon nanotube (CNT) sheets, which exhibit all the component functions of SCs: activated materials, conductive materials, and current collectors. Repeated bending tests validated the robustness of the flexible SCs. The SCs demonstrated extremely high durability with >99.9% capacitance retention after 50 000 bending cycles. Furthermore, we observed that the orientation angle of the CNT sheets with respect to the current flow direction (theta) was crucial for determining the performance of SCs. The SCs with CNT sheets oriented in the current flow direction (theta = 0 degrees) showed a higher scan rate and robustness than those with other CNT sheet orientations (theta = 45 or 90 degrees), because of the ease of access of charge carriers to the electrodes of the entire CNT sheet. Well-designed flexible and durable CNT-SCs can drastically improve the performance of future flexible devices.

    DOI: 10.1021/acsanm.1c04236

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  • Copper-incorporation for polytypism and bandgap engineering of MAPbBr3 perovskite thin films with enhanced near-Infrared photocurrent-response

    Amr Elattar, Jiban Kangsabanik, Kodai Nakao, Kosei Tsutsumi, Hiroo Suzuki, Takeshi Nishikawa, Kristian S. Thygesen, Yasuhiko Hayashi

    Materials Chemistry Frontiers   6 ( 18 )   2690 - 2702   2022

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    Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry (RSC)  

    Formation of secondary phase polytypes through incorporation of copper into MAPbBr3 perovskite yields bandgap reduction with generation of near-IR photocarriers.

    DOI: 10.1039/d2qm00491g

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  • Structure modulation for bandgap engineered vacancy-ordered Cs3Bi2Br9 perovskite structures through copper alloying

    Amr Elattar, Libor Kobera, Jiban Kangsabanik, Hiroo Suzuki, Sabina Abbrent, Takeshi Nishikawa, Kristian S. Thygesen, Jiri Brus, Yasuhiko Hayashi

    Journal of Materials Chemistry C   10 ( 35 )   12863 - 12872   2022

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    Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry (RSC)  

    Light absorption enhancement was achieved through structure modulation of the Cs3Bi2Br9 perovskite crystal via Cu-alloying. The Cs3Bi2Br9 perovskite retains its matrix structure with homogeneously distributed Cs2CuBr4 large domains.

    DOI: 10.1039/d2tc01762h

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  • Improved room-temperature thermoelectric characteristics in F4TCNQ-doped CNT yarn/P3HT composite by controlled doping

    May Thu Zar Myint, Takeshi Nishikawa, Hirotaka Inoue, Kazuki Omoto, Aung Ko Ko Kyaw, Yasuhiko Hayashi

    ORGANIC ELECTRONICS   90   2021.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER  

    High room-temperature thermoelectric performance is important for low-grade waste heat power generation as there are plenty of heat thrown away uselessly in our daily life, most of which are below 100 degrees C. However, most of the thermoelectric materials are limited to high temperature application. In this work, room-temperature thermoelectric power factor of carbon nanotube (CNT) yarn is improved by controlled doping, which is achieved by making composite with poly 3-hexylthiophene -2, 5-diyl (P3HT) followed by doping with 2, 3, 5, 6-tetrafluo-7, 7, 8, 8-tetracyanoquinodimethane (F4TCNQ). The temperature-dependent Seebeck coefficient based on power-law model suggests that P3HT shifts the Fermi energy of CNT yarn towards the valence band edge, and reduces the ionic scattering and carrier relaxation time. As a result, the Seebeck coefficient is increased while the variation of Seebeck coefficient with temperature is reduced, and hence, the room-temperature thermoelectric power factor is improved. With controlled doping, the power factor of CNT yarn/P3HT composite reaches to 1640-2160 mu W m(-1)K(-2) at the temperature range of 25-100 degrees C, which is higher than that of CNT yarn alone.

    DOI: 10.1016/j.orgel.2020.106056

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  • Single crystal of two-dimensional mixed-halide copper-based perovskites with reversible thermochromism

    Amr Elattar, Hiroo Suzuki, Ryuji Mishima, Kodai Nakao, Hiromi Ota, Takeshi Nishikawa, Hirotaka Inoue, Aung Ko Ko Kyaw, Yasuhiko Hayashi

    Journal of Materials Chemistry C   9 ( 9 )   3264 - 3270   2021

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry (RSC)  

    <p>Facile synthesis of single crystal of two-dimensional mixed-halide copper-based perovskites with tunable band gaps and their capability of exfoliation and reversible thermochromism.</p>

    DOI: 10.1039/d0tc04307a

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  • Synthesis and characterization of conductive flexible cellulose carbon nanohorn sheets for human tissue applications. International journal

    Karthik Paneer Selvam, Taichi Nagahata, Kosuke Kato, Mayuko Koreishi, Toshiyuki Nakamura, Yoshimasa Nakamura, Takeshi Nishikawa, Ayano Satoh, Yasuhiko Hayashi

    Biomaterials research   24   18 - 18   2020

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    Background: Conductive sheets of cellulose and carbon nanomaterials and its human skin applications are an interesting research aspect as they have potential for applications for skin compatibility. Hence it is needed to explore the effects and shed light on these applications. Method: To fabricate wearable, portable, flexible, lightweight, inexpensive, and biocompatible composite materials, carbon nanohorns (CNHs) and hydroxyethylcellulose (HEC) were used as precursors to prepare CNH-HEC (Cnh-cel) composite sheets. Cnh-cel sheets were prepared with different loading concentrations of CNHs (10, 20 50,100 mg) in 200 mg cellulose. To fabricate the bio-compatible sheets, a pristine composite of CNHs and HEC was prepared without any pretreatment of the materials. Results: The obtained sheets possess a conductivity of 1.83 × 10- 10 S/m and bio-compatible with human skin. Analysis for skin-compatibility was performed for Cnh-cel sheets by h-CLAT in vitro skin sensitization tests to evaluate the activation of THP-1 cells. It was found that THP-1 cells were not activated by Cnh-cel; hence Cnh-cel is a safe biomaterial for human skin. It was also found that the composite allowed only a maximum loading of 100 mg to retain the consistent geometry of free-standing sheets of < 100 μm thickness. Since CNHs have a unique arrangement of aggregates (dahlia structure), the composite is homogeneous, as verified by transmission electron microscopy (TEM) and, scanning electron microscopy (SEM), and other functional properties investigated by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), conductivity measurement, tensile strength measurement, and skin sensitization. Conclusion: It can be concluded that cellulose and CNHs sheets are conductive and compatible to human skin applications.

    DOI: 10.1186/s40824-020-00194-3

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  • Influence of pressure of nitrogen gas on structure and thermoelectric properties of acid-treated PEDOT:PSS films Reviewed

    May Thu Zar Myint, Hirotaka Inoue, Susumu Ichimura, Takeshi Nishikawa, Yuta Nishina, Aung Ko Ko Kyaw, Yasuhiko Hayashi

    Journal of Materials Science: Materials in Electronics   30 ( 14 )   13534 - 13542   2019.7

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    © 2019, Springer Science+Business Media, LLC, part of Springer Nature. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is the most commonly investigated conductive polymer due to its unique thermoelectric properties. Several post treatments using various acids have been reported to improve the thermoelectric properties of PEDOT:PSS. In most articles, however, only the role of acids on the structure and thermoelectric properties of PEDOT:PSS were reported. In this article, we report the major role of the pressure of nitrogen gas (N2) on the structure and thermoelectric properties of PEDOT:PSS after treatment with various acids at optimized temperatures. After treatment with acids followed by N2 gas-passing, electrical conductivity enhances significantly. Therefore, N2 gas-passing after acid treatments results in higher thermoelectric properties than other traditional acid treatment methods. The enhancement in electrical conductivity is attributed to the removal of insulating PSS and the conformational change of the PEDOT chain. Furthermore, the pressure of N2 is responsible for the additional conformation of PEDOT chain, favoring the linear orientation of the PEDOT structure and resulting in an improvement of the electrical conductivity.

    DOI: 10.1007/s10854-019-01721-2

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  • Bond Dissociation Triggering Molecular Disorder in Amorphous H2O Reviewed

    M Hada, Y Shigeeda, S Koshihara, T Nishikawa, Y Yamashita, Y Hayashi

    The Journal of Physical Chemistry A   122 ( 49 )   9579 - 9584   2018.11

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  • Rapid growth of tall and dense double-wall carbon nanotubes and its wire application by dry spinning process

    8 ( 1 )   29 - 33   2017.7

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  • Investigation of the ionization balance of bismuth-to-tin plasmas for the extreme ultraviolet light source based on a computer-generated collisional radiative model Reviewed

    Akira Sasaki, Atsushi Sunahara, Katsunobu Nishihara, Takeshi Nishikawa

    AIP ADVANCES   6 ( 10 )   2016.10

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER INST PHYSICS  

    The ionization balance of the bismuth-to-tin plasmas is systematically investigated on the basis of a collisional radiative model, which has been generated using a computer algorithm to analyze the level structure of multiple charged ions to construct the model. The atomic energy levels and rate coefficients corresponding to the model are calculated using the HULLAC code. With this method, we investigate the plasma temperature, which is required to obtain emission in the extreme ultraviolet wavelength range from 13.5 nm to thewater window. (C) 2016 Author(s).

    DOI: 10.1063/1.4964496

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  • Atomic process modeling in dense hydrogenic plasmas by nearest neighbor approximation Reviewed

    T. Nishikawa*

    Journal of Physics: Conference Series   688 ( 1 )   2016.4

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1088/1742-6596/688/1/012077

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  • Atomic process modeling in dense hydrogenic plasmas by nearest neighbor approximation Reviewed

    Takeshi Nishikawa

    Journal of Physics: Conference Series   688 ( 1 )   2016.3

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    DOI: 10.1088/1742-6596/688/1/012099

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  • Atomic processes and equation of state of high Z plasmas for EUV sources and their effects on the spatial and temporal evolution of the plasmas Reviewed

    Akira Sasaki, Atushi Sunahara, Hiroyuki Furukawa, Katsunobu Nishihara, Takeshi Nishikawa, Fumihiro Koike

    8TH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS (IFSA 2013)   688 ( 1 )   2016

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IOP PUBLISHING LTD  

    Laser-produced plasma (LPP) extreme ultraviolet (EUV) light sources have been intensively investigated due to potential application to next-generation semiconductor technology. Current studies focus on the atomic processes and hydrodynamics of plasmas to develop shorter wavelength sources at lambda = 6.x nm as well as to improve the conversion efficiency (CE) of lambda = 13.5 nm sources. This paper examines the atomic processes of mid-z elements, which are potential candidates for lambda = 6.x nm source using n=3-3 transitions. Furthermore, a method to calculate the hydrodynamics of the plasmas in terms of the initial interaction between a relatively weak prepulse laser is presented.

    DOI: 10.1088/1742-6596/688/1/012099

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  • 22aAE-1 Evaluation of Ionic and Atomic Potential Considering Electron Distribution in Plasmas and Its Application for Computing Electron State Densities

    NISHIKAWA Takeshi

    Meeting Abstracts of the Physical Society of Japan   71   965 - 965   2016

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    Language:Japanese   Publisher:The Physical Society of Japan (JPS)  

    DOI: 10.11316/jpsgaiyo.71.1.0_965

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  • Self-Assembled C-60 Fullerene Cylindrical Nanotubes by LLIP method Reviewed

    Venkata Krishna R. Rao, P. S. Karthik, Venkata K. Abhinav, Zaw Lin, May Thu Zar Myint, Takeshi Nishikawa, Masaki Hada, Yoshifumi Yamashita, Yasuhiko Hayashi, Surya Prakash Singh

    2016 IEEE 16TH INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO)   303 - 306   2016

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:IEEE  

    In this article, we report C60 Fullerene Nano Cylindrical Tubes (FNCT). The FNCTs were synthesized by a liquid-liquid interface precipitation (LLIP) method using m-Xylene as a saturating solvent and TBA (Tetra butyl alcoholic) as precipitation agent leading to the formation of FNCTs with uniquely structured and well oriented size and shape. The experiment was conducted in a closed atmosphere maintaining a low temperature. The main advantage of these structures is that they are stable up to 5 months in normal room temperature. Characterizations were done to the FNCTs and concluded to have applications in the field of electronics. Enhanced semiconducting properties have been observed in the nanostructures which can be used in the application of solar cells, FET transistors, etc.

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  • 19aCP-12 Definition of bound state in atomic process model based on nearest neighbor approximation

    NISHIKAWA Takeshi

    Meeting Abstracts of the Physical Society of Japan   70   705 - 705   2015

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    Language:Japanese   Publisher:The Physical Society of Japan (JPS)  

    DOI: 10.11316/jpsgaiyo.70.2.0_705

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  • 21aCJ-9 Partial dislocation motion incidental to the shrinkage of stacking fault introduced by electron beam irradiation in 4H-SiC epi-film

    Yamashita Y., Shimomura T., Nishikawa T., Hayashi Y.

    Meeting Abstracts of the Physical Society of Japan   70   2683 - 2683   2015

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    Language:Japanese   Publisher:The Physical Society of Japan (JPS)  

    DOI: 10.11316/jpsgaiyo.70.1.0_2683

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  • Modeling of free electronic state density in hydrogenic plasmas based on nearest neighbor approximation Reviewed

    Takeshi Nishikawa

    PHYSICS OF PLASMAS   21 ( 7 )   072713   2014.7

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER INST PHYSICS  

    Most conventional atomic models in a plasma do not treat the effect of the plasma on the free-electron state density. Using a nearest neighbor approximation, the state densities in hydrogenic plasmas for both bound and free electrons were evaluated and the effect of the plasma on the atomic model (especially for the state density of the free electron) was studied. The model evaluates the electron-state densities using the potential distribution formed by the superposition of the Coulomb potentials of two ions. The potential from one ion perturbs the electronic state density on the other. Using this new model, one can evaluate the free-state density without making any ad-hoc assumptions. The resulting contours of the average ionization degree, given as a function of the plasma temperature and density, are shifted slightly to lower temperatures because of the effect of the increasing free-state density. (C) 2014 AIP Publishing LLC.

    DOI: 10.1063/1.4891440

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  • Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source (vol 107, 113303, 2010)

    Akira Sasaki, Atsushi Sunahara, Hiroyuki Furukawa, Katsunobu Nishihara, Shinsuke Fujioka, Takeshi Nishikawa, Fumihiro Koike, Hayato Ohashi, Hajime Tanuma

    JOURNAL OF APPLIED PHYSICS   108 ( 2 )   2010.7

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    Language:English   Publisher:AMER INST PHYSICS  

    DOI: 10.1063/1.3464541

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  • Atomic processes in the LPP and LA-DPP EUV sources

    Akira Sasaki, Katsunobu Nishihara, Atsushi Sunahara, Hiroyuki Furukawa, Takeshi Nishikawa, Fumihiro Koike

    ALTERNATIVE LITHOGRAPHIC TECHNOLOGIES   7271   2009

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    Language:English   Publishing type:Research paper (international conference proceedings)   Publisher:SPIE-INT SOC OPTICAL ENGINEERING  

    We investigate characteristic feature of the atomic radiation from tin plasmas, which allow one to obtain high power EUV emission at lambda = 13.5nm 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.

    DOI: 10.1117/12.814026

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  • Plasma physics and radiation hydrodynamics in developing an extreme ultraviolet light source for lithography Reviewed

    Katsunobu Nishihara, Atsushi Sunahara, Akira Sasaki, Masanori Nunami, Hajime Tanuma, Shinsuke Fujioka, Yoshinori Shimada, Kazumi Fujima, Hiroyuki Furukawa, Takako Kato, Fumihiro Koike, Richard More, Masakatsu Murakami, Takeshi Nishikawa, Vasilii Zhakhovskii, Kouhei Gamata, Akira Takata, Hirofumi Ueda, Hiroaki Nishimura, Yasukazu Izawa, Noriaki Miyanaga, Kunoki Mima

    PHYSICS OF PLASMAS   15 ( 5 )   056708-1 - 056708-11   2008.5

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    Extreme ultraviolet (EUV) radiation from laser-produced plasma (LPP) has been thoroughly studied for application in mass production of next-generation semiconductor devices. One critical issue for the realization of an LPP-EUV light source for lithography is the conversion efficiency (CE) from incident laser power to EUV radiation of 13.5-nm wavelength (within 2% bandwidth). Another issue is solving the problem of damage caused when debris reaches an EUV collecting mirror. Here, we present an improved power balance model, which can be used for the optimization of laser and target conditions to obtain high CE. An integrated numerical simulation code has been developed for the target design. The code agrees well with experimental results not only for CE but also for detailed EUV spectral structure. We propose a two-pulse irradiation scheme for high CE, and reduced ion debris using a carbon dioxide laser and a droplet or a punch-out target. Using our benchmarked numerical simulation code, we find a possibility to obtain CE up to 6-7%, which is more than twice that achieved to date. We discuss the reduction of ion energy within the two-pulse irradiation scheme. The mitigation of energetic ions by a magnetic field is also discussed, and we conclude that no serious instability occurs due to large ion gyroradius. (c) 2008 American Institute of Physics.

    DOI: 10.1063/1.2907154

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  • EUV Source Design Flexibility for Lithography Reviewed

    T Nishikawa, A Sunahara, A Sasaki, and K Nishihara

    Journal of Physics: Conference Series   112   42065   2008.4

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  • Detailed atomic modeling of Sn plasmas for the EUV source Reviewed

    A. Sasaki, A. Sunahara, K. Nishihawra, T. Nishikawa, F. Koike, and H.Tanuma

    Journal of Physics: Conference Series   112   42062   2008.4

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  • Advanced laser-produced EUV light source for HVM with conversion efficiency of 5-7% and B-field mitigation of ions

    K. Nishihara, A. Sunahara, A. Sasaki, S. Fujioka, Y. Shimada, M. Nunami, H. Tanuma, M. Murakami, T. Aota, K. Fujima, H. Furukawa, T. Nishikawa, F. Koike, R. More, T. Kato, V. Zhakhovskii, K. Gamata, H. Ueda, H. Nishimura, Y. Yuba, K. Nagai, N. Miyanaga, Y. Izawa, K. Mima

    Proceedings of SPIE - The International Society for Optical Engineering   6921 ( 33 )   2008.2

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    We propose a new scheme for high conversion efficiency from laser energy to 13.5 nm extreme ultra violet emission within 2 % band width, a double pulse laser irradiation scheme with a tin droplet target. We consider two-color lasers, a Nd:YAG laser with 1.06 μm in wavelength as a prepulse and a carbon dioxide laser with 10.6 μm in wavelength for a main pulse. We show the possibility of obtaining a CE of 5 - 7 % using a benchmarked radiation hydro code. We have experimentally tested the new scheme and observed increase of CE greater than 4 %. We show many additional advantages of the new scheme, such as reduction of neutral debris, energy reduction of debris ions, and decrease of out of band emission. We also discuss debris problems, such as ion sputtering using newly developed MD simulations, ion mitigation by a newly designed magnetic coil using 3-PIC simulations and tin cleaning experiments.

    DOI: 10.1117/12.769086

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  • レーザー生成スズプラズマからの極端紫外光発生の放射流体シミュレーション Reviewed

    砂原淳、佐々木明、田沼肇、西原功修、*西川亘、小池文博、藤岡慎介、青田達也、山浦道照、島田義則、西村博明、井澤靖和、宮永憲明、三間圀興

    プラズマ・核融合学会誌   920   2007.4

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  • Theoretical and experimental databases for high average power EUV light source by laser produced plasma Reviewed

    H. Nishimura, K. Nishihara, S. Fujioka, T. Aota, T. Ando, M. Shimomura, K. Sakaguchi, Y. Simada, M. Yamaura, K. Nagai, T. Norimatsu, A. Sunahara, M. Murakami, A. Sasaki, H. Tanuma, F. Koike, K. Fuijma, C. Suzuki, S. Morita, T. Kato, T. Kagawa, T. Nishikawa, N. Miyanaga, Y. Izawa, K. Mima

    AIP Conference Proceedings   926   270 - 280   2007

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    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. © 2007 American Institute of Physics.

    DOI: 10.1063/1.2768859

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  • Development of EUV light source by laser-produced plasma

    Y. Izawa, N. Miyanaga, H. Nishimura, S. Fujioka, T. Aota, Y. Tao, S. Uchida, Y. Shimada, K. Hashimoto, M. Yamaura, K. Nishihara, M. Murakami, A. Sunahara, H. Furukawa, A. Sasaki, W. Nishikawa, H. Tanuma, T. Norimatsu, K. Nagai, Q. Gu, M. Nakatsuka, H. Fujita, K. Tsubakimoto, H. Yoshida, K. Mima

    Journal De Physique. IV : JP   133   1161 - 1165   2006.6

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    We have been developing an EUV light source by laser-produced plasma for the use of EUV lithography system under the Leading Project promoted by MEXT. The project aims at understanding physics of laser plasma EUV source and providing database and guidelines for the practical EUV source. Progresses in theoretical modeling and experimental results are briefly reported. © EDP Sciences.

    DOI: 10.1051/jp4:2006133237

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  • Numerical analysis of energy trasport by intense resonance line in Lithium plasmas

    *T. Nishikawa, K. Gamada, A. Sunahara, K. Nishihara

    Journal de physique IV   2006.6

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  • Progress in LPP EUV source development at Osaka University

    Noriaki Miyanaga, Hiroaki Nishimura, Shinsuke Fujioka, Tatsuya Aota, Shigeaki Uchida, Michiteru Yamaura, Yoshinori Shimada, Kazuhisa Hashimoto, Keiji Nagai, Takayoshi Norimatsu, Katsunobu Nishihara, Masakatsu Murakami, Vasilli Zhakhovskii, Young Gwang Kang, Atsushi Sunahara, Hiroyuki Furukawa, Akira Sasaki, Takeshi Nishikawa, Masahiro Nakatsuka, Hisanori Fujita, Koji Tsubakimoto, Hidetsugu Yoshida, Yasukazu Izawa, Kunioki Mima

    EMERGING LITHOGRAPHIC TECHNOLOGIES X, PTS 1 AND 2   6151   U567 - U574   2006

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    For EUV lithography the generation of clean and efficient light source and the high-power laser technology are key issues. Theoretical understanding with modeling and simulation of laser-produced EUV source based on detailed experimental database gives us the prediction of optimal plasma conditions and their suitable laser conditions for different target materials (tin, xenon and lithium). With keeping etendue limit the optimal plasma size is determined by an appropriate optical depth which can be controlled by the combination of laser wavelength and pulse width. The most promising candidate is tin (Sri) plasma heated by Nd:YAG laser with a pulse width of a few ns. Therefore the generation technology of clean Sri plasma is a current important subject to be resolved for practical use. For this purpose we have examined the feasibility of laser-driven rocket-like injection of extremely mass-limited Sri or SnO2 (punched-out target) with a speed exceeding 100m/s. Such a mass-limited low-density target is most preferable for substantial reduction of ion energy compared with usual bulk target. For high average power EUV generation we are developing a laser system which is CW laser diode pumped Nd:YAG ceramic laser (master oscillator and power amplifier system) operating at 5-10 kHz repetition rate. The design of practical laser for EUV source is being carried out based on the recent performance of > 1 kW output power.

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  • Opacity effect on extreme ultraviolet radiation from laser-produced tin plasmas

    Shinsuke Fujioka, Hiroaki Nishimura, Katsunobu Nishihara, Akira Sasaki, Atsushi Sunahara, Tomoharu Okuno, Nobuyoshi Ueda, Tsuyoshi Ando, Yezheng Tao, Yoshinori Shimada, Kazuhisa Hashimoto, Michiteru Yamaura, Keisuke Shigemori, Mitsuo Nakai, Keiji Nagai, Takayoshi Norimatsu, Takeshi Nishikawa, Noriaki Miyanaga, Yasukazu Izawa, Kunioki Mima

    Physical Review Letters   95 ( 23 )   2005.12

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    Opacity effects on extreme ultraviolet (EUV) emission from laser-produced tin (Sn) plasma have been experimentally investigated. An absorption spectrum of a uniform Sn plasma generated by thermal x rays has been measured in the EUV range (9-19 nm wavelength) for the first time. Experimental results indicate that control of the optical depth of the laser-produced Sn plasma is essential for obtaining high conversion to 13.5 nm-wavelength EUV radiation; 1.8% of the conversion efficiency was attained with the use of 2.2 ns laser pulses. © 2005 The American Physical Society.

    DOI: 10.1103/PhysRevLett.95.235004

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  • Characterization of extreme ultraviolet emission from laser-produced spherical tin plasma generated with multiple laser beams

    Y. Shimada, H. Nishimura, M. Nakai, K. Hashimoto, M. Yamaura, Y. Tao, K. Shigemori, T. Okuno, K. Nishihara, T. Kawamura, A. Sunahara, T. Nishikawa, A. Sasaki, K. Nagai, T. Norimatsu, S. Fujioka, S. Uchida, N. Miyanaga, Y. Izawa, C. Yamanaka

    Applied Physics Letters   86 ( 5 )   1 - 3   2005.1

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    Spherical solid tin targets were illuminated uniformly with twelve beams from the Gekko XII laser system to create spherical plasmas, and the extreme ultraviolet (EUV) emission spectra from the plasmas were measured. The highest conversion efficiency of 3% to 13.5 nm EUV light in 2% bandwidth was attained for an irradiance of around 5× 1010 W cm2. The experimental results were reproduced fairly well using a theoretical model taking the power balance in the plasma into consideration. © 2005 American Institute of Physics.

    DOI: 10.1063/1.1856697

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  • Estimations on high energy ions and neutral particles from LPP EUV light sources Reviewed

    H. Furukawa, T. Kawamura, T. Nishikawa, A. Sasaki, K. Fujima, S. Fujioka, H. Nishimura, K. Nishihara, N. Miyanaga, Y. Izawa, C. Yamanaka

    Progress in Biomedical Optics and Imaging - Proceedings of SPIE   5751 ( II )   789 - 797   2005

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    We have developed an integrated Laser Ablation Fluid RAdiation simulation Code (LAFRAC) to estimate the behaviors of highly energetic ions and neutral particles from LPP EUV light sources, and estimated recombination and charge transfer processes between the particles from laser-produced Xe EUV light sources. We clarify that charge transfer effects greatly affect on the number density of neutral particles, especially high energy ( more than roughly 500 eV ) neutral particles.

    DOI: 10.1117/12.597959

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  • Effect of the satellite lines and opacity on the extreme ultraviolet emission from high-density Xe plasmas

    SASAKI A.

    Applied Physics Letters   85   5857 - 5859   2004.12

  • Theoretical simulation of extreme UV radiation source for lithography

    K. Fujima, K. Nishihara, T. Kawamura, H. Furukawa, T. Kagawa, F. Koike, R. More, M. Murakami, *T. Nishikawa, A. Sasaki, A. Sunahara, V. Zhakhovskii, T. Fujimoto, H. Tanuma

    Proc. SPIE   2004.4

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  • レーザー生成球対称Snプラズマからの極短紫外線(EUV)放射特性

    西村博明25名20番目

    プラズマ・核融合学会誌   2004.4

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

    Tohru Kawamura, Atsushi Sunahara, Kouhei Gamada, Kazumi Fujima, Fumihiro Koike, Hiroyuki Furukawa, Takeshi Nishikawa, Akira Sasaki, Takashi Kagawa, Richard More, Takako Kato, Masakatsu Murakami, Vasilli Zhakhovskii, Hajime Tanuma, Takashi Fujimoto, Yoshinori Shimada, Michiteru Yamaura, Kazuhisa Hashimoto, Shigeaki Uchida, Chiyoe Yamanaka, Tomoharu Okuno, Takahiro Hibino, Nobuyoshi Ueda, Ryoji Matsui, Yezheng Tao, Mitsuo Nakai, Keisuke Shigemori, Shinsuke Fujioka, Keiji Nagai, Takayoshi Norimatsu, Hiroaki Nishimura, Katsunobu Nishihara, Noriaki Miyanaga, Yasukazu Izawa

    Proceedings of SPIE - The International Society for Optical Engineering   5374 ( PART 2 )   918 - 925   2004.4

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    Extreme Ultra Violet (EUV) light source produced by laser irradiation emits not only the desired EUV light of 13 ∼ 14 nm (about 90 eV) but also shorter x-rays. For example, emissions around 4 ∼ 8 nm (about 150 ∼ 300 eV) and 1 ∼ 2.5 nm (about 0.5 ∼ 1.2keV) 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.

    DOI: 10.1117/12.535031

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  • Simulation of the EUV spectrum of Xe and Sn plasmas

    Akira Sasaki, Katsunobu Nishihara, Fumihiro Koike, Takashi Kagawa, *Takeshi Nishikawa, Kazumi Fujima, Tohru Kawamura and Hiroyuki Furukawa

    special issue of the IEEE, Journal of Selected Topics in Quantum Electronics on "Short wavelength and EUV Lasers"   2004.1

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

    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

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    A design window of laser and plasma parameters required for an extreme ultraviolet (EUV) radiation source for practical application for the next generation of lithography has been introduced. We present a simple analytical model of conversion efficiency from laser energy to radiation energy with a wavelength of 13.5 nm with 2 % bandwidth, by considering power balance of laser produced high-z plasma. We also investigate dependence of the EUV emission from tin and tin-oxide plasmas on laser intensity and wavelength in spherical geometry using the GEKKO XII laser system. It is found that the conversion efficiency into a 2% bandwidth about 13.5 nm has a maximum of a few percent near the laser intensity 10 11 W/cm 2. The efficiency is about the same for 1.053 μm and 0.527 μm laser wavelengths. A scaling law of the conversion efficiency on the laser intensity obtained agrees fairly well with the experimental results. The model also explains many features of the spectrum observed in the experiments.

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    Other Link: http://orcid.org/0000-0002-3978-8427

  • Simple atomic model based on the plasma microfield

    Takeshi NISHIKAWA

    Proceedings of Second International Conference on Inertial Fusion Sciences and Applications 2001, September 9-14, 2001, Kyoto (IFSA2001)   2001.4

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  • Novel Laboratory Fusion Sources

    T. Kenmotsu, *T. Nishikawa, R. More

    Proceedings of Second International Conference on Inertial Fusion Sciences and Applications 2001, September 9-14, 2001, Kyoto (IFSA2001)   2001.4

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  • Energy level data recommendation by screening constant

    T Nishikawa

    JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER   67 ( 1 )   43 - 54   2000.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:PERGAMON-ELSEVIER SCIENCE LTD  

    Energy level data recommendation by the screening constant is more useful and more accurate than that by quantum defect for high-Z ions. While the quantum defect converges to a small value as Z increases, the screening constant monotonically decreases. Z dependence of the screening constant is approximately Z(3) for Z = 10-40, Z(3.5) for Z = 40-70, and Z(4) for Z &gt; 70. By the simple Z dependence, we have made a fitting formula for lie-like ions. The same Z dependence of the screening constant has been found in different ions, Li-like, Be-like, and etc. This simple Z(3) dependence of the screening constant could be explained as the spin-orbit interaction of the hydrogenic wave function in the Coulomb potential. (C) 2000 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0022-4073(99)00192-2

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  • Simple expression of occupation probability in the "chemical picture"

    T Nishikawa

    ASTROPHYSICAL JOURNAL   532 ( 1 )   670 - 672   2000.3

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    We propose a simple analytical expression for the occupation probability of highly excited states in low-density hydrogenic plasmas. This expression is based on the "chemical picture" and is derived by using the Holtsmark held and the saddle-point estimates. We believe that this expression would be a basic model in the chemical picture since ion-ion correlation is neglected and the simple saddle-point estimates are used. If the density of the plasma is low enough and the temperature is high enough, this expression would be a good approximation. If not, this model gives roughly the critical principal quantum number at which bound states disappear and the basic reference numerical values of the occupation probability for quantitative comparison study with numerical results by detailed modeling.

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  • SOFT-X-RAY SPECTRA OF HIGHLY IONIZED ELEMENTS WITH ATOMIC NUMBERS RANGING FROM 57 TO 82 PRODUCED BY COMPACT LASERS

    GM ZENG, H DAIDO, T NISHIKAWA, H TAKABE, S NAKAYAMA, H ARITOME, K MURAI, Y KATO, M NAKATSUKA, S NAKAI

    JOURNAL OF APPLIED PHYSICS   75 ( 4 )   1923 - 1930   1994.2

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    X-ray emission spectra in the spectral range of 2-13 nm from 19 kinds of material with high atomic numbers (lanthanum through lead) were recorded with a grazing incidence spectrometer equipped with a microchannel plate detector. There is an intense, narrow spectral band in these spectra which shifts toward shorter wavelength and becomes weak in intensity with increasing atomic number. The materials were irradiated either by a 4 J/35 ns slab Nd:glass laser or by a 0.5 J/8 ns Nd:YAG laser. The absolute photon intensities of the spectra were determined with an absolutely calibrated charge coupled device camera. The peak spectral brightness of the emission at the peak intensity of the spectral band for lanthanum plasma was estimated to be 2.1 X 10(16) photons/s/mm2/mrad2 in 0.1% bandwidth. The origin of the narrow, intense spectral bands in the recorded spectra and their dependence on target materials and laser wavelength are interpreted.

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  • COMPUTATIONAL MODEL FOR NON-LTE ATOMIC PROCESS IN LASER-PRODUCED PLASMAS

    H TAKABE, T NISHIKAWA

    JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER   51 ( 1-2 )   379 - 395   1994.1

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    A computational model for simulating hydro-radiation phenomena has been studied relating to the partially ionized gold plasma produced by irradiation of intense laser light. The screened hydrogenic model with l-splitting effect and the average ion model are used to determine the atomic state of gold ions in the collisional radiative equilibrium. A statistical method is used to evaluate the spectral opacity and emissivity due to the clusters of line transitions. The x-ray conversion rate and spectrum calculated with the hydrodynamic code ILESTA coupled with the opacity and emissivity are compared with those observed experimentally.

    DOI: 10.1016/0022-4073(94)90101-5

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  • PLASMA X-RAY SOURCE OF VARIOUS MATERIALS PRODUCED BY COMPACT SOLID-STATE LASERS

    GM ZENG, H DAIDO, S NAKAYAMA, K MURAI, T NISHIKAWA, S KIYOKAWA, H TAKABE, H ARITOME, M NAKATSUKA, Y KATO, S NAKAI

    APPLICATIONS OF LASER PLASMA RADIATION   2015   45 - 56   1994

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    DOI: 10.1117/12.168000

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  • LINE-PROFILE MODELING FOR NON-LTE PARTIALLY IONIZED PLASMAS BASED ON AVERAGE ATOM MODEL WITH L-SPLITTING

    T NISHIKAWA, H TAKABE, K MIMA

    LASER AND PARTICLE BEAMS   11 ( 1 )   81 - 87   1993

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:CAMBRIDGE UNIV PRESS  

    We have developed a new opacity modeling of partially ionized high-Z plasma to solve radiation transport in fluid codes. The average atom model is used to describe the electronic state of the plasma. The electronic state of the plasma is determined by solving the collisional radiative equilibrium model. We have taken into account the electron energy level splitting owing to the difference in the azimuthal quantum number. To model the line groups made of the same electronic transitions from ions indifferent charge states, we used a statistical method and calculated the distribution of the charge states from the averaged electron population in each bound state. By using the new opacity model, we can well reproduce the X-ray spectra from the plasmas. It is found that the DELTAn = 0 transition can explain the peaked spectra near hnu = 300 eV and I-splitted emission of the n = 5-4 transition can explain the flat spectra in the region of hnu = 400-800 eV seen in the experiments.

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  • NON-LTE ATOMIC MODELING FOR LASER-PRODUCED PLASMAS

    H TAKABE, S NAKAMURA, T NISHIKAWA

    LASER AND PARTICLE BEAMS   11 ( 1 )   119 - 126   1993

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:CAMBRIDGE UNIV PRESS  

    Atomic modeling of high-Z partially ionized plasma is essential for simulating radiation hydrodynamics of laser-produced plasma. A collisional-radiative model based upon an average atom model is used to calculate plasma opacity and emissivity. Because line radiations are most dominant in such plasma, the detail configuration accounting (DCA) for electronic state is required. We propose a statistical method to carry out the DCA with the use of the average population of bound electrons. Further modeling of line group made of the same transition from ions in different change states is discussed by considering the detail structure (hierarchy) of the line group.

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  • Statistical Approach for Calculating Opacities of High-Z Plasmas

    Journal Plasma Fusion Research   68,145   1992

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  • 統計手法を用いた高Zプラズマの原子モデル

    核融合研究   68,145   1992

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  • X-RAY-EMISSION AND TRANSPORT IN GOLD PLASMAS GENERATED BY 351-NM LASER IRRADIATION

    H NISHIMURA, H TAKABE, K KONDO, T ENDO, H SHIRAGA, K SUGIMOTO, T NISHIKAWA, Y KATO, S NAKAI

    PHYSICAL REVIEW A   43 ( 6 )   3073 - 3085   1991.3

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    Emission and transport characteristics of sub-keV x rays in laser-produced gold plasmas are investigated. Absolute x-ray spectra under three different experimental conditions have been measured with high spectral resolution to study dependences of x-ray emission on laser incidence angles, irradiation intensity, and thickness of a foil target. Simulations by a one-dimensional hydrodynamic code, which incorporates a detailed atomic physics, replicate quite well the general x-ray emission features obtained in the experiments. There remain, however, discrepancies in some details of spectral shapes, notably in the range between 0.5 and 0.9 keV. It is also shown that the transport of radiation heat wave deduced from x-ray emissions at the front and the rear sides of a thin gold foil may be interpreted by the self-similar solutions presented by Pakula and Sigel [Phys. Fluids. 28, 232 (1985); 29, 1340 (E) (1986)] with an approximated gold opacity under local thermodynamic equilibrium.

    DOI: 10.1103/PhysRevA.43.3073

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  • ION KINETIC EFFECT ON FUSION REACTION-RATE

    T NISHIKAWA, H TAKABE, K MIMA

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   28 ( 10 )   2004 - 2010   1989.10

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Books

  • EUV Sources for Lithography

    Katsunobu Nishihara, Akira Sasaki, Atsushi Sunahara, *Takeshi Nishikawa( Role: Sole author ,  Chapter 11 Conversion Efficiency of LPP Sources)

    SPIE Press  2005.4 

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  • Novel Laboratory Fusion Sources(共著)

    Elsevier, Proceedings of Second International Conference on Inertial Fusion Sciences and Applications, September 9-14, 2001, Kyoto (IFSA2001)  2001 

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  • Simple atomic model based on the plasma microfield

    Elsevier, Proceedings of Second International Conference on Inertial Fusion Sciences and Applications 2001, September 9-14, 2001, Kyoto (IFSA2001)  2001 

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MISC

  • エネルギー輸送の違いから見たカーボンナノチューブの通電加熱の効果

    中條大樹, 井上寛隆, 黒田泰平, 森本大我, 林拓磨, 徳永知春, 池田直, 横谷尚睦, 藤森和博, 羽田真毅, 西川亘, 山下善文, 紀和利彦, 林靖彦

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   65th   2018

  • ポリジアセチレンの熱・光誘起による相転移とそれに伴う構造変化

    森光生, 羽田真毅, 林靖彦, 山下善文, 西川亘, 井上寛隆, 伊東千尋, 腰原伸也

    応用物理・物理系学会中国四国支部合同学術講演会講演予稿集   2018   2018

  • 高分子線材/CNT紡績糸マルチフィラメント・ソフトアクチュエータの開発

    井上寛隆, 吉山貴之, 中條大樹, 齋藤慶考, 羽田真毅, 西川亘, 山下善文, 宝田亘, 松本英俊, 林靖彦

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   65th   2018

  • 時間分解電子線回折法を用いたEuBaCo2O5.38の構造ダイナミクス計測

    羽田 真毅, 鈴木 達也, 阿部 伸行, 有馬 孝尚, 沖本 洋一, 腰原 伸也, 慶尾 直哉, 村上 寛虎, 西川 亘, 山下 善文, 林 靖彦, 横谷 尚睦, 松尾 二郎, 浅香 透

    日本物理学会講演概要集   72   1128 - 1128   2017.1

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    DOI: 10.11316/jpsgaiyo.72.2.0_1128

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  • 10aAE-4 Threading dislocation motion in Sb-doped SiGe thin films with various Ge content

    Yamashita Yoshifumi, Maki Shinya, Fushimi Tatsuya, Ohno Yutaka, Yonenaga Ichiro, Nishikawa Takeshi, Hayashi Yasuhiko

    Meeting abstracts of the Physical Society of Japan   69 ( 2 )   706 - 706   2014.8

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  • 28pAM-12 Partial dislocation motion in 4H-SiC with/without electron beam irradiation

    Yamashita Yoshifumi, Shimomura Takuya, Fujii Yuji, Nishikawa Takeshi, Hayashi Yasuhiko

    Meeting abstracts of the Physical Society of Japan   69 ( 1 )   933 - 933   2014.3

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  • 26pGY-3 Atomic Process Modeling base on the distribution of the nearest neighbor atom

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   66 ( 1 )   257 - 257   2011.3

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  • 25pQA-15 State Density of Electrons and Average Charge Calculation Based on the Plasma Microfield

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   65 ( 2 )   200 - 200   2010.8

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  • 20aTJ-13 State Density of Electrons and Average Charge Calculation Based on the Binary Collision of Ions

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   65 ( 1 )   225 - 225   2010.3

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  • 23pRA-11 Atomic Modeling of the plasma EUV sources

    Sasaki A., Nishihara K., Sunahara A., Nishikawa T., Koike F., Tanuma H.

    Meeting abstracts of the Physical Society of Japan   63 ( 1 )   154 - 154   2008.2

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  • Analysis of the emission spectrum of Xe and Sn

    A. Sasaki, K. Nishihara, A. Sunahara, T. Nishikawa, F. Koike, K. Kagawa, H. Tanuma

    EMERGING LITHOGRAPHIC TECHNOLOGIES X, PTS 1 AND 2   6151   61513W   2006

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    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 Sri emission, which determines fraction of usable EUV power, is discussed with respect to its dependence on the plasma temperature, density as well as the optical depth.

    DOI: 10.1117/12.655938

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  • 19pXK-5 Atomic modeling of the Euv sources

    Sasaki A., Nishihara C., Maehara H., Nishikawa T., Sunahara A., Koike F., Kagawa T., Tanuma H.

    Meeting abstracts of the Physical Society of Japan   60 ( 2 )   98 - 98   2005.8

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  • 19pXK-4 Simulation on laser ablation with time dependent population kinetics

    Furnkawa Hiroyuki, Sasaki Akira, Nishikawa Takeshi, Nishihara Katsunobu, Mima Kunioki

    Meeting abstracts of the Physical Society of Japan   60 ( 2 )   98 - 98   2005.8

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  • 24aXG-14 Opacity structure and conversion efficiency of EUV emitting plasmas

    Fujioka S., Nishimura H., OkunoT.

    Meeting abstracts of the Physical Society of Japan   60 ( 1 )   197 - 197   2005.3

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  • 30pWH-8 New Screened Hydrogenic Model involving n, l-splitting

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   59 ( 1 )   249 - 249   2004.3

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  • 28aB02 Characterization of EVU emission from Laser Produced Plasma

    NISHIMURA Hiroaki, SHIGEMORI Keisuke, NAKAI Mitsuo, FUJIOKA Shinsuke, Sohnatzadeh F.L, Zhakhovickii V, More R

    プラズマ・核融合学会年会予稿集   ( 20 )   2003.11

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    DOI: 10.1585/jspf.80.325

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  • State density of free electrons including ionic potential in a plasma

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   56 ( 2 )   148 - 148   2001.9

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  • Atomic model based on semi-classical theory II

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   56 ( 1 )   128 - 128   2001.3

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  • Plasma effects reduced into elementary atomic processes

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   55 ( 1 )   114 - 114   2000.3

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  • Atomic model based on semi-classical theory

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   55 ( 1 )   121 - 121   2000.3

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  • 25aB-1 Calculation of statistical weight of highly excited states using the Stark effect by plasma microfield

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   54 ( 2 )   104 - 104   1999.9

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  • Calculation of statistical weight of highly excited states using the Stark effect by plasma microfield

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   53 ( 2 )   898 - 898   1998.9

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  • Calculation of Stark Profile of Lβ line by first Order Pertubed Wavefunction

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   53 ( 1 )   824 - 824   1998.3

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  • 7p-YN-4 Theoretical Calculation on Stark Effect Base on 1st Order Perturbed Wavefunction

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   52 ( 2 )   942 - 942   1997.9

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  • Theoretical Calculation of the Hydrogen Spectrum

    NISHIKAWA Takeshi

    1997 ( 26 )   7 - 10   1997.5

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  • 31a-YG-5 X-ray spectroscopic analysis of laser-produced plasmas

    NISHIKAWA Takeshi

    Meeting abstracts of the Physical Society of Japan   52 ( 1 )   867 - 867   1997.3

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  • 30a-R-1 Electronic Population of High-Z plasma including I-distribution

    Nishikawa T.

    Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1995 ( 4 )   213 - 213   1995.9

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  • 27a-YA-6 Energy Level Description of He-like Ions by Screened Hydrogenic Model

    Nishikawa T

    Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1995 ( 4 )   19 - 19   1995.9

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  • Recommended Atomic Data for Collisional-radiatire Model of LI-like Ions and Gain Cakulation for la Li-like Ai Ions in the Recombining Plasmas

    NIFS-DATA-30, NATIPMA; OMSTOTITE FPR FISOPM SCOEMCE   9103p   1995

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  • 2a-L-11 Screened Hydorgenic Model for Opacity Calculations

    Nishikawa T

    Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1994 ( 4 )   23 - 23   1994.8

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  • 30p-E-5 Model dependence of atomic process in simulating population inversion of recombining Li-like Aluminum Plasma II

    Nishikawa T, Nishihara K

    Abstracts of the meeting of the Physical Society of Japan. Annual meeting   49 ( 2 )   391 - 391   1994.3

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  • 15a-DA-1 Model dependence of atomic process in simulating population inversion of recombining Li-like Aluminum Plasma

    Nishikawa T., Nishihara K.

    Abstracts of the meeting of the Physical Society of Japan. Sectional meeting   1993 ( 2 )   461 - 461   1993.9

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  • Atomic Modeling and Radiation Transport in Laser Produced Plasmas

    Technology Reports of the Osaka University   41,253   1991

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Presentations

  • レーザー、放電励起EUV光源における原子過程および放電初期過程の考察

    佐々木明,西原功修,砂原淳,*西川亘,小池文博,古河裕之

    第70回応用物理学会学術講演会 

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    Event date: 2009.9.8

    Presentation type:Oral presentation (general)  

    Venue:富山大学  

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  • The atomic model of the Sn plasmas for the EUV sources International conference

    Akira Sasaki, Atsushi Sunahara, Katsunobu Nishihara, Takeshi Nishikawa, Fumihiro Koike, Hajime Tanuma

    14th Internationl Conference on the Physics of Highly Charged Ions 

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    Event date: 2008.9.2

    Presentation type:Poster presentation  

    Venue:Chofu, Tokyo, JAPAN  

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  • EUV~軟X線領域のプラズマ 光源のモデリング

    佐々木 明、1西原 功修、2砂原 淳、 3西川 亘、4小池 文博、2古河 裕之

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    Event date: 2008.4

    Presentation type:Oral presentation (general)  

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  • Advanced laser-produced EUV light source for HVM with conversion efficiency of 5-6% and B-field mitigation of ions (Invited Paper) International conference

    Katsunobu Nishihara, 間に8名, Takeshi Nishikawa*, 後ろに7名

    EUV Source II, SPIE Advance Lithography 

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    Event date: 2008.2.27

    Presentation type:Oral presentation (general)  

    Venue:San Jose, California, USA  

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  • EUV Source Desgin Flexility for Lithography

    *Nishikawa Takeshi, Sunahara Atsushi, Sasaki Akira, Nishihara Katsunobu

    Fifth International Conference on Inertial Fusion Science and Applications 

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    Event date: 2007.9.11

    Venue:Kobe  

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  • Snの輻射放出・吸収係数に対する発光線波長の精度の影響

    佐々木明、西原功修、砂原淳、*西川亘、小池文博、香川貴司、田沼肇

    第54回応用物理学関係連合講演会 

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    Event date: 2007.3.29

    Venue:青山学院大学 相模原キャンパス  

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  • レーザー生成錫プラズマからの極端紫外光発生の最適化

    砂原淳、西原功修、佐々木明、*西川亘、藤岡慎介、青田達也、山浦道照、島田義則、西村博明、宮永憲明、井澤靖和、三間圀興

    レーザー学会学術講演会第27回年次大会 

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    Event date: 2007.1.18

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  • Detailed Modeling of Atomic Process and Radiative Transfer of the EUV Source Plasmas

    Akira Sasaki, Atsushi Sunahara, Katsunobu Nishihara, *Takeshi Nishikawa, Fumihiro Koike, Takashi Kagawa, Hajime Tanuma

    EUV Source Workshop 

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    Event date: 2006.10.19

    Venue:Barcelona, Spain  

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  • Laser and Target Optimization for the Highest Conversion to 13.5 nm EUV Light with Laser Produced, Minimum-Mass Tin Plasma

    Hiroaki Nishimura他18名11番目

    5nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2006.10.15

    Venue:Barcelona, Spain  

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  • Radiation Hydrodynamic Simulation for LPP EUV Sources

    Atsushi Sunahara他11名4番目

    5nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2006.10.15

    Venue:Barcelona, Spain  

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  • Systematics of Atomic 4d-4f Transitions of Atomic Ions in EUVL Source Plasmas and Neighboring Atomic Numbers

    Fumihiro Koike, Akira Sasaki, Katsunobu Nishihara, Atsushi Sunahara, Takeshi Nishikawa, Takashi Kagawa, Hajime Tanuma

    5nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2006.10.15

    Venue:Barcelona, Spain  

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  • Theoretical Guidelines of LPP-EUV Sources for HVM

    Katsunobu Nishihara他21名10番目

    5nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2006.10.15

    Venue:Barcelona, Spain  

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  • Modeling of the Atomic Processes in EUVL Source Plasmas

    Akira Sasaki, Katsunobu Nishihara, Atsushi Sunahara, *Takeshi Nishikawa, Fumihiro. Koike, Takashi Kagawa, Hajime Tanuma

    5nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2006.10.15

    Venue:Barcelona, Spain  

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  • EUV光源用Sn, Xeの詳細原子モデル

    佐々木明、西原功修、砂原淳、*西川亘、小池文博、香川貴司、田沼肇

    日本物理学科2006年秋季大会 

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    Event date: 2006.9.23

    Venue:千葉大学西千葉キャンパス  

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  • レーザー生成プラズマからの極端紫外光発生の2次元シミュレーションII

    砂原淳、西原功修、佐々木明、西川亘、青田達也、山浦道照、藤岡慎介、島田義則、西村博明、宮永憲明、井澤靖和、三間国興

    第67回応用物理学会学術講演会 

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    Event date: 2006.8.30

    Venue:立命館大学びわこ・くさつキャンパス  

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  • EUV光源の原子過程モデルの高精度化

    佐々木明、西原功修、砂原淳、西川亘、香川貴司、小池文博、田沼肇

    第67回応用物理学会学術講演会 

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    Event date: 2006.8.30

    Venue:立命館大学びわこ・くさつキャンパス  

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  • Xe, Snプラズマの原子モデル改良の課題

    佐々木明、西原功修、前原宏昭、砂原淳、*西川亘、小池文博、香川貴司、田沼肇

    応用物理学会 

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    Event date: 2006.3.24

    Venue:武蔵工業大学世田谷キャンパス  

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  • LPP EUV光源のターゲット材料としてのスズ、およびスズ化合物の理論解析

    *西川亘、砂原淳、佐々木明、西原功修

    応用物理学会 

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    Event date: 2006.3.24

    Venue:武蔵工業大学世田谷キャンパス  

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  • レーザー生成プラズマからの極端紫外光発生の2次元放射流体シミュレーション

    砂原淳、西原功修、佐々木明、*西川亘、古河裕之、前原宏昭、山浦道照、藤岡慎介、島田義則、西村博明、宮永憲明、井澤靖和、三間圀興

    応用物理学会 

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    Event date: 2006.3.24

    Venue:武蔵工業大学世田谷キャンパス  

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  • Analysis of the emission spectrum of Xe and Sn

    A. Sasaki, K. Nishihara, F. Koike, T. Kagawa, *T. Nishikawa, A. Sunahara, H. Tanuma

    SPIE microlithography 2006 

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    Event date: 2006.2.23

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  • レーザープラズマによるEUVリソグラフィー用光源の開発

    宮永憲明他31名30番目

    レーザー学会学術講演会第27回年次大会 

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    Event date: 2006.1.17

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  • Characteristics of Emission Lines from Xe, Sn, and Other Species at EUV Region

    F. Koike, K. Nishihara, A. Sunahara, H. Maehara, *T. Nishikawa, A. Sasaki, T. Kagawa, H. Tanuma

    4nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2005.11.7 - 2005.11.9

    Venue:San Diego, CA, USA  

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  • High Conversion to 13.5 nm EUV and Debris Mitigation with Mass-limited Plasmas Generated with Laser

    Hiroaki Nishimura他24人14番目

    4nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2005.11.7 - 2005.11.9

    Venue:San Diego, CA, USA  

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  • Progress in LPP EUV Source Development by Japan MEXT Project

    Yasukazu Izawa他23人18番目

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    Event date: 2005.11.7 - 2005.11.9

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  • Radiative properties of Xe and Sn plasmas

    A. Sasaki, K. Nishihara, A. Sunahara, H. Maehara, *T. Nishikawa, F. Koike, T. Kagawa, H. Tanuma

    4nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2005.11.7 - 2005.11.9

    Venue:San Diego, CA, USA  

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  • Theoretical Modeling and Optimization of LPP EUV Light Source

    K. Nishihara他23人12番目

    4nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2005.11.7 - 2005.11.9

    Venue:San Diego, CA, USA  

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  • Physics of laser-produced Li plasma EUV light source

    *T. Nishikawa, A. Sunahara, A. Sasaki, K. Nishihara

    4nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2005.11.7 - 2005.11.9

    Venue:San Diego, CA, USA  

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  • EUV光源プラズマの原子モデルの特性

    佐々木明、西原功修、前原宏昭、*西川亘、砂原淳、小池文博、田沼肇

    日本物理学会 

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    Event date: 2005.9.19

    Venue:同志社大学京田辺キャンパス  

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  • 時間依存の原子過程を含んだレーザーアブレーションのシミュレーション

    古河裕之、佐々木明、*西川亘、西原功修、三間圀興

    日本物理学会 

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    Event date: 2005.9.19

    Venue:同志社大学京田辺キャンパス  

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  • Xe, Snプラズマのemissivity, opacityの特性

    佐々木明、西原功修、前原宏昭、砂原淳、*西川亘、小池文博、香川貴司、田沼肇

    応用物理学会 

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    Event date: 2005.9.10

    Venue:徳島大学 常三島キャンパス  

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  • レーザー生成EUVプラズマからの高エネルギー粒子に関する考察

    古河裕之、佐々木明、*西川亘、藤岡慎介、西村博明、西原功修、宮永憲明、井澤靖和、三間圀興、山中千代衛

    応用物理学会 

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    Event date: 2005.9.10

    Venue:徳島大学 常三島キャンパス  

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  • 輻射励起を考慮したレーザー生成プラズマからのEUV光発生特性

    前原宏昭、西原功修、砂原淳、古河裕之、佐々木明、*西川亘

    応用物理学会 

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    Event date: 2005.9.10

    Venue:徳島大学 常三島キャンパス  

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  • 小委員会活動による教育改善活動・・・岡山大学工学部電気電子工学科

    小西正躬、藤原耕二、金範錫、佐薙稔、*西川亘、石山武、野木茂次

    電気学会教育フロンティア研究会 

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    Event date: 2005.8.4

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  • EUV光源のターゲット材料としてのリチウムの理論解析

    *西川亘、蒲田康平、古河裕之、砂原淳、佐々木明、西原功修

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • 輻射流体シミュレーションによるレーザー生成プラズマからの極端紫外光放射特性解析

    砂原淳、西原功修、蒲田幸平、前原宏昭、佐々木明、*西川亘、古河裕之、島田義則、山浦道照、陶業争、内田成明、藤岡慎介、西村博明、宮永憲明、井澤靖和

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • 詳細原子モデルによるXe, Snプラズマのemissivity, opacity

    佐々木明、西原功修、蒲田幸平、砂原淳、*西川亘、小池文博、香川貴司、田沼肇

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • 種々のターゲット物質のEUV変換効率と輻射輸送

    蒲田幸平、西原功修、砂原淳、古河裕之、佐々木明、*西川亘、河村徹

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • LPP-UEV光における輻射励起・電離の効果

    前原宏昭、西原功修、蒲田幸平、砂原淳、古河裕之、佐々木明、*西川亘

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • LPP-EUV光源から発生する光速イオンの速度分布モデルリング

    村上匡且、姜永光、西原功修、西村博明、藤岡慎介、陶業争、山浦道照、長井圭治、内田成明、宮永憲明、砂原淳、*西川亘、佐々木明、井澤靖和

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • レーザー生成EUV Xeプラズマからの高エネルギー粒子に関する考察

    古河裕之、河村徹、*西川亘、佐々木明、藤間一美、藤岡慎介、西村博明、西原功修、宮永憲明、井澤靖和、山中千代衛

    応用物理学会 

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    Event date: 2005.3.31

    Venue:埼玉大学  

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  • EUV放射プラズマのオパシティー構造と放射効率の関係

    藤岡慎介、西村博明、奥野智晴、島田義則、橋本和久、一木理史、重森啓介、中井光男、陶業争、上田修義、安藤強史、谷勤翠、長井圭治、乗松孝好、佐々木明、*西川亘、砂原淳、西原功修、宮永憲明、井澤靖和田沼肇

    日本物理学会 

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    Event date: 2005.3.24

    Venue:東京理科大学野田キャンパス  

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  • EUV光源用Xe, Snプラズマの原子過程モデリング

    佐々木明、西原功修、蒲田幸平、*西川亘、砂原淳、小池文博、香川貴司、田沼肇

    日本物理学会 

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    Event date: 2005.3.24

    Venue:東京理科大学野田キャンパス  

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  • Estiamtions on high energy ions and neutral particles from LPP EUV light sources

    H. Furukawa, T. Kawamura, *T. Nishikawa, A. Sasaki, K. Fujima, S. Fujioka, H. Nishimura, K. Nishihara, N. Miyanaga, Y. Izawa, C. Yamanaka

    SPIE 30th Annual International Symposium on Microlithography 

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    Event date: 2005.2.27 - 2005.3.4

    Venue:San Jose  

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  • Modeling of the atomic processes in the laser-plamsa EUV sources

    A. Sasaki, K. Nishihaar, F. Koike, K. Kagawa, H. Tanuma, A. Sunahara, K. Gamada, *T. Nishikawa

    SPIE 30th Annual International Symposium on Microlithography 

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    Event date: 2005.2.27 - 2005.3.4

    Venue:San Jose  

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  • EUV light source design by Li target LPP

    *T. Nishikawa, K. Gamada, K. Nishihara

    EUVL Source Workshop 

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    Event date: 2005.2.27

    Venue:San Jose, USA  

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  • レーザー生成スズプラズマからのEUV光発生の放射流体シミュレーション

    砂原淳、西原功修、蒲田幸平、*西川亘、佐々木明、古河裕之、島田義則、山浦道照、内田成明、藤岡慎介、西村博明、宮永憲明、井澤靖和

    プラズマ・核融合学会第21回年会 

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    Event date: 2004.11.24

    Venue:静岡コンベンションアーツセンター「グランシップ」  

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  • 新しい遮蔽水素モデルを用いたEUV放射プラズマの原子過程モデル

    *西川亘、佐々木明、砂原淳、古河裕之、西原功修

    プラズマ・核融合学会第21回年会 

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    Event date: 2004.11.24

    Venue:静岡コンベンションアーツセンター「グランシップ」  

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  • Modeling of LPP EUV Light Source at Japan MEXT Leading Project

    K. Nishihara他21名11番目

    3nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2004.11.1 - 2004.11.4

    Venue:Miyazaki, Japan  

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  • Atomic models for radiation transport in laser plasma hydrodynamic simulation of EUV light source

    *Takeshi Nishikawa, Akira Sasaki, Hiroyuki Furukawa, Atsushi Sunahara, and Katsunobu Nishihara

    3nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2004.11.1 - 2004.11.4

    Venue:Miyazaki, Japan  

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  • Experimental Database of LPP EUV Sources at ILE and ILT

    N. Miyanaga他28人27番目

    3nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2004.11.1 - 2004.11.4

    Venue:Miyazaki, Japan  

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  • Numerical Analysis of Extreme Ultra-Violet Emission from Laser-Produced Tin Plasmas

    Atsushi Sunahara他14人3番目

    3nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2004.11.1 - 2004.11.4

    Venue:Miyazaki, Japan  

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  • The Role of Interference and Correlations in 13.5 nm Radiations of Sn and Xe Atomic Ions -- For Precise and Accurate Determination of Sprctral

    F. Koike, K. Nishihara, A. Sasaki, T. Kagawa, *T. Nishikawa, K. Fujima, T. Kawamura, and H. Furukawa

    3nd International Extreme Ultra-Violet Lithography (EUVL) Symposium 

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    Event date: 2004.11.1 - 2004.11.4

    Venue:Miyazaki, Japan  

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  • Atomic Data for Laser Produced Plasma Extreme Ultra Violet Light Source

    K. Nishihara他21人11番目

    Joint Meeting 14th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion 4th International Conference on Atomic and Molecular Data and Their Applications 

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    Event date: 2004.10.5 - 2004.10.8

    Venue:Toki, Gifu, Japan  

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  • Precise and Accurate Calculations of Electronic Transitions in Heavy Atomic Ions Relevant to Extreme Ultra-Violet Light Sources

    F. Koike, K. Nishihara, A. Sasaki, T. Kagawa, *T. Nishikawa, K. Fujima, T. Kawamura, H. Furukawa

    Joint Meeting 14th International Toki Conference on Plasma Physics and Controlled Nuclear Fusion 4th International Conference on Atomic and Molecular Data and Their Applications 

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    Event date: 2004.10.5 - 2004.10.8

    Venue:Toki, Gifu, Japan  

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  • EUV光源プラズマの原子過程モデルと流体シミュレーション

    *西川亘、砂原淳、佐々木明、古河裕之、西原功修

    日本物理学会 

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    Event date: 2004.9.12

    Venue:青森大学  

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  • Interference effects in correlated transitions of heavy atomic ions

    F. Koike, K. Nishihara, A. Sasaki, T. Kagawa, *T. Nishikawa, K. Fujima, T. Kawamura, H. Furukawa

    12th International Conference on the Physics of Highly Charged Ions 

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    Event date: 2004.9.6 - 2004.9.11

    Venue:Vilnus, Lithuania  

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  • パワーバランス解析モデルを用いたEUV2%BWへの変換効率の考察

    蒲田幸平、西原功修、砂原淳、古河裕之、佐々木明、*西川亘、河村徹

    応用物理学会 

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    Event date: 2004.9.2

    Venue:東北学院大学(泉キャンパス)  

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  • EUV光源プラズマ流体シミュレーションのための原子過程モデルとデータセット

    *西川亘、佐々木明、古河裕之、砂原淳、西原功修

    応用物理学会 

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    Event date: 2004.9.2

    Venue:東北学院大学(泉キャンパス)  

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  • 輻射流体シミュレーションによるEUV放射の波長依存性の解析

    砂原淳、西原功修、*西川亘、佐々木明、古河裕之、蒲田幸平、山浦道照、藤岡慎介、島田義則、内田成明、橋本和久、西村博明、井澤靖和

    応用物理学会 

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    Event date: 2004.9.2

    Venue:東北学院大学(泉キャンパス)  

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  • Xe,Snプラズマの詳細原子モデル

    佐々木明、西原功修、砂原淳、*西川亘

    応用物理学会 

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    Event date: 2004.9.2

    Venue:東北学院大学(泉キャンパス)  

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  • Simulations on laser ablation and its applications

    Hiroyuki Furukawa, Tohru Kawamura, Atsushi Sunahara, *Takeshi Nishikawa, Katsunobu Nishihara, Chiyoe Yamanaka

    High-Power Laser Ablation 2004 

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    Event date: 2004.4.25 - 2004.4.30

    Venue:Taos, New Mexico, USA  

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  • n, l分離を含んだ新しい遮蔽水素モデル

    西川亘

    日本物理学会 

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    Event date: 2004.3.30

    Venue:九州大学箱崎キャンパス  

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  • EUV光源プラズマのスペクトルの構造の解析

    佐々木明、西原功修、西村博明、河村徹、砂原淳、古河裕之、西川亘、小池文博、藤間一美、香川貴司、加藤隆子、R. More

    日本物理学会 

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    Event date: 2004.3.30

    Venue:九州大学箱崎キャンパス  

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  • 相変化、詳細なレーザー吸収過程を考慮したEUVプラズマ輻射流体シミュレーション

    古河裕之、河村徹、砂原淳、島田義則、山浦道照、西川亘、蒲太幸平、西原功修、宮永憲明、井澤靖和

    応用物理学会 

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    Event date: 2004.3.30

    Venue:東京工科大学  

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  • 輻射流体シミュレーションによるレーザー生成プラズマからのEUV放射の解析

    砂原淳、西川亘、古河裕之、河村徹、蒲太幸平、西原功修、島田義則、藤岡慎介、西村博明、宮永憲明、山浦道照、内田成明、井澤靖和

    応用物理学会 

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    Event date: 2004.3.30

    Venue:東京工科大学  

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  • 自然科学の楽しさを伝えたい?岡山大学サイエンス・スクールの試み?

    長屋智之、奈良重俊、*西川亘、山下信彦、稲田佳彦、味野道信、木村吉伸

    電気学会教育フロンティア研究会 

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    Event date: 2004.3.4

    Venue:岡山  

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

    T. Kawamura, K. Fujima, F. Koike, H. Furukawa, A. Sunahara, T. Nishikawa, A. Sasaki, T. Kagawa, R. More, M. Murakami, V. Zhakhovskii, T. Fujimoto, H. Tanuma, K. Nishihara

    SPIE 29th Annual International Symposium on Microlithography 

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    Event date: 2004.2.26

    Venue:anta Clara, CA, USA  

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  • Theoretical simulation of extreme UV radiation source for lithography

    K. Fujima, K. Nishihara, T. Kawamura, H. Furukawa, T. Kagawa, F. Koike, R. More, M. Murakami, T. Nishikawa, A. Sasaki, A. Sunahara, V. Zhakhovskii, T. Fujimoto, H. Tanuma

    SPIE 29th Annual International Symposium on Microlithography 

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    Event date: 2004.2.25

    Venue:anta Clara, CA, USA  

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  • Atomic models and hydrodynamic simulation for laser-plasma EUV source

    Takeshi Nishikawa, Akira Sasaki, Hiroyuki Furukawa, Atsushi Sunahara, Katsunobu Nishihara

    EUVL Source Workshop 

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    Event date: 2004.2.22

    Venue:Santa Clara, USA  

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  • 輻射流体コードによるEUV放射の数値シミュレーション

    砂原淳、古河裕之、河村徹、西川亘、村上匡且、西原功修、宮永憲明、井澤靖和

    プラズマ・核融合学会年会 

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    Event date: 2003.11.28

    Venue:茨城県立県民文化センター  

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  • レーザー生成プラズマからの極短紫外線(EUV)放射特性

    西村博明他36名中25番目

    プラズマ・核融合学会年会 

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    Event date: 2003.11.28

    Venue:茨城県立県民文化センター  

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  • EUV光源開発のためのレーザーアブレーション輻射流体シミュレーション

    古河裕之、河村徹、砂原淳、西川亘、藤間一美、西原功修、宮永憲明、井澤靖和

    プラズマ・核融合学会年会 

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    Event date: 2003.11.23

    Venue:茨城県立県民文化センター  

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  • Simulation of the EUV spectrum of Xe and Sn plasmas

    N. Miyanaga他36名のうち19番目

    Progress in Understanding of Laser-Produced Plasmas for EUV Source 16th Annual Meeting of IEEE, Laser and Electro-Optics Society, (LEOS2003) 

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    Event date: 2003.10.27 - 2003.10.30

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  • Laser-Produced-Plasma for EUV Light Source for Lithography

    K. Nishihara他36名の2番目

    Ultrashort high-energy radiation and matter 

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    Event date: 2003.10.7 - 2003.10.10

    Venue:Varenna, Italy  

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  • Radiation Hydrodynamic Simulation of Laser-Produced Plasma for EUVL

    A. Sunahara, H. Furukawa, T. Kawamura, T. Nishikawa, M. Murakami, K. Nishihara

    2nd International Extreme UltraViolet Symposium 

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    Event date: 2003.9.30 - 2003.10.2

    Venue:Antwerp, Belgium  

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  • Japan MEXT Leading Project for Laser-Produced-Plasma EUV Light Source Development

    K. Nishihara他36名の10番目

    2nd International Extreme UltraViolet Symposium 

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    Event date: 2003.9.30 - 2003.10.2

    Venue:Antwerp, Belgium  

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  • Characterization of EUV Emission from Laser Produced Low-Density Tin-oxidized plasmas

    H. Nishimura他17名の17番目

    2nd International Extreme UltraViolet Symposium 

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    Event date: 2003.9.30 - 2003.10.2

    Venue:Antwerp, Belgium  

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  • Experimental Study on Basic Properties of Laser-Produced Plasma as an EUV Source on GEKKO XII

    M. Nakai他24名の24番目

    2nd International Extreme UltraViolet Symposium 

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    Event date: 2003.9.30 - 2003.10.2

    Venue:Antwerp, Belgium  

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  • Evaluation of Emission Efficiency at 13.5-nm EUV Source form One-Dimensional Spherical Plasma without Lateral Heat Transport an Density Gradient

    M. Yamaura他23名23番目

    2nd International Extreme Ultra-Violet Lithography Symposium 

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    Event date: 2003.9.30 - 2003.10.2

    Venue:Antwerp, Belgium  

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  • Dependence of EUV Emission Properties on Drive Laser Wavelength

    M. Yamaura他23名の23番目

    2nd International Extreme UltraViolet Symposium 

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    Event date: 2003.9.30 - 2003.10.2

    Venue:Antwerp, Belgium  

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  • EUV光源開発のためのレーザーアブレーション輻射流体シミュレーション

    古河裕之、河村徹、砂原淳、西川亘、藤間一美、佐々木明、村上匡且、西原功修、宮永憲明、井澤靖和

    応用物理学会 

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    Event date: 2003.9.30

    Venue:福岡大学  

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  • EUV光源プラズマ流体シミュレーションのための簡便な平均イオンモデル

    西川亘、古河裕之、砂原淳、西原功修

    応用物理学会 

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    Event date: 2003.9.30

    Venue:福岡大学  

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  • Theoretical Modeling of Laser-Produced Plasma for Development of Extreme UV Radiation Source for Lithography

    K. Nishihara, *T. Nishikawa, A. Sasaki, T. Kawamura, A. Sunahara, H. Furukawa, M. Murakami, R. More, K. Fujima, F. Koike, T. Kagawa, V. Zhakhovskii, T. Kato, H. Tanuma, H. Nishimura, M. Nakai, 他20名

    International Conference of Fusion Science 2003 

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    Event date: 2003.9.7 - 2003.9.12

    Venue:Monterey  

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  • 岡山大学電気電子工学科における実験科目への取り組み?物理学実験?

    小笠原悟司、藤原耕二、鶴田健二、佐薙稔、山下善文、石山武、西竜志、*西川亘、東辻千枝子、宮城大輔、小松原均、中野正典、安原清隆

    電気学会教育フロンティア研究会資料FIE-03-13 

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    Event date: 2003.5.30

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  • EUV光源開発のためのXeイオンのエネルギー準位の評価

    古河裕之、香川貴司、小池文博、佐々木明、藤間一美、西川亘、More Richard、西原功修

    第50回応用物理学関係連合講演会 

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    Event date: 2003.3.29

    Venue:横浜  

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  • XeプラズマのEUVスペクトルの理論解析

    佐々木明、西原功修、西村博明、古河裕之、西川亘、藤間一美、More Richard、小池文博、香川貴司

    第50回応用物理学関係連合講演会 

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    Event date: 2003.3.29

    Venue:横浜  

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  • 水熱量計を用いた交流電力測定の学生実験

    西川亘、数乗有、八田和道、藤田英明

    日本物理学会 

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    Event date: 2002.3.25

    Venue:草津  

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  • イオンポテンシャルを考慮したプラズマ中自由電子の状態密度II

    西川亘、数乗有、八田和道、藤田英明

    日本物理学会 

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    Event date: 2002.3.24

    Venue:草津  

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  • イオンポテンシャルを考慮したプラズマ中自由電子の状態密度

    西川 亘

    日本物理学会 

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    Event date: 2001.9.19

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  • Simple atomic model based on the plasma microfield

    Takeshi NISHIKAWA

    Second International Conference on Inertial Fusion Sciences and Applications 

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    Event date: 2001.9.13

    Venue:Kyoto  

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  • Novel Laboratory Fusion Sources

    T. Kenmotsu*, T. Nishikawa, R. More* *核融合科学研究所

    Second International Conference on Inertial Fusion Sciences and Applications 

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    Event date: 2001.9.10

    Venue:Kyoto  

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  • 水熱量計を用いた交流電力測定の学生実験

    西川亘、数乗有、八田和道、藤田英明

    電気・情報関連学会中国支部第52回連合大会講演論文集 

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    Event date: 2001.4

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  • 半古典近似を用いた原子モデルII

    西川 亘

    日本物理学会 

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    Event date: 2001.3.29

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  • 半古典近似を用いた原子モデ

    西川 亘

    日本物理学会 

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    Event date: 2001.3.25

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  • プラズマ効果の原子素過程への要素還元

    西川 亘

    日本物理学会 

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    Event date: 2001.3.24

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  • シュタルク効果に基づく高励起状態数の計算

    西川亘

    日本物理学会 

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    Event date: 1999.9.25

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Research Projects

  • Development of lightweight artificial muscle with polymer threads and carbon nanotube yarn towards true human support

    Grant number:19K21946  2019.06 - 2021.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Research (Exploratory)

    Hayashi Yasuhiko

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    Grant amount:\6370000 ( Direct expense: \4900000 、 Indirect expense:\1470000 )

    To realize an artificial muscle that stretches and contracts elastomeric yarns using Joule heat generated by applying an electric current to carbon nanotube (CNT) webs, the concept of a "stiff" actuator mechanism, which has been developed so far, cannot be used. The elastic modulus of the CNTs is larger than that of the elastomer, which prevents the elastomeric yarn from stretching and thus prevents the elastomeric yarn from stretching sufficiently. In order to solve this problem, we proposed a method of wrapping CNT webs around elastomeric yarns, and by optimizing the fabrication procedures, we were able to achieve higher force generation than that of bio-muscular or nylon 6,6 yarns.

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  • Development of ultra high strength more than 6GPa ultra light wegiht carbon nanotube spun yarn

    Grant number:18H01708  2018.04 - 2021.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    HAYASHI Yasuhiko

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    Grant amount:\17810000 ( Direct expense: \13700000 、 Indirect expense:\4110000 )

    In this study, carbon nanotube (CNT) yarns were fabricated from tall and high-density, few-walled CNT forest synthesized on the substrate by dry spinning method to achieve CNT yarns with tensile strength exceeding the strength of carbon fibers, which is a benchmark for practical use. The shape and diameter change of the catalytic metal particles from room temperature to the initial temperature of CNT synthesis was clarified, which enabled the selective synthesis of double-layer CNTs. We also found that the removal of residual amorphous carbon and the structural change to graphene occurred simultaneously when the entire CNT yarn was heated by joule heating in vacuum and extreme ethane gas. Furthermore, by using a spinning technique to orient the CNTs in one direction, a high strength of over 2.5 GPa was achieved.

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  • Modeling of structure formation in the intial stage of laser plasma interaction and its application to the study of EUV source

    Grant number:26610195  2014.04 - 2018.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    Sasaki Akira

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    Grant amount:\3120000 ( Direct expense: \2400000 、 Indirect expense:\720000 )

    Theoretical investigation of the particle emission from short pulse laser irradiated solid targets is carried out, and simulation code is developed, for its application to the analysis of laser pumped plasma (LPP) Extreme Ultra-Violet (EUV) light source.
    We develop the algorithms for the reorganization of mesh, along the distribution of the material, for the 2 dimensional Lagrangian hydrodynamics model. Furthermore, the liquid-to-gas transition is taken into account firstly by determining the ratio of volumes of liquid and gas region corresponding to the average temperature and density, and secondly by splitting the target cell and redistributing the mass and internal energy to the divided cells. Test calculations are carried out for uniformly heated tin cylinder to show the initial bubble formation to subsequent decomposition of the target into particles.

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  • Investigation of phase transition processes arises from atomic and radiative property of plasmas for EUV and X-ray laser applications

    Grant number:23340185  2011.04 - 2014.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    SASAKI Akira, NISHIHARA Katsunobu, SUNAHARA Atsushi, FURUKAWA Hiroyuki, NISHIKAWA Takeshi, KOIKE Fumihiro

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    Grant amount:\17550000 ( Direct expense: \13500000 、 Indirect expense:\4050000 )

    We investigate the mechanism of formation of the inhomogeneous structure in laser produced plasmas and discharge plasmas, by taking the phase transition processes into account, which originate from atomic and radiative properties of plasmas. We develop a detailed atomic model of tungsten, which is interested in fusion plasmas. The size of the model is parameterized, and accuracy of the calculation of mean charge and radiative power loss is improved by sensitivity studies and benchmark calculations. We also investigate percolation transition in discharge plasmas. We investigate development of discharge in SF6 based on its material properties such as ionization and attachment coefficient to reproduce experimental observations from initial partial discharge to later growth of the stepped leader to cause breakdown. By combining both atomic model, radiative transfer model and phase transition model understanding of structure formation in the plasmas will be improved.

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  • Development of an integrated model of the hybrid pumping plasma light source based on laser assisted discharge

    Grant number:20340166  2008 - 2010

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    SASAKI Akira, NISHIHARA Katsunobu, SUNAHARA Atsushi, FURUKAWA Hiroyuki, KOIKE Fumihiro, NISHIKAWA Takeshi, KAI Takeshi, NUNAMI Masanori

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    Grant amount:\17030000 ( Direct expense: \13100000 、 Indirect expense:\3930000 )

    Modeling methods of laser-plasma hybrid pumping plasma light sources are investigated. On the modeling of plasma atomic processes, a model, which calculates level population, emissivity and opacity of the plasma with a reasonable accuracy and is capable of reproducing emission spectrum, is developed. Calculated dependence of the plasma radiation pressure, which shows non-monotonic behavior with respect to density, suggests instability of the plasmas. The model is also applied to evaluate the emission characteristics of Tb plasma for future EUV applications. On the modeling of plasma radiation hydrodynamics, importance of modeling methods, which can calculate the temporal and spatial structure formation, is discussed. Instead of existing MHD and other fluid and particle approach, it is found that using the percolation model, the initial structure of the discharge can be reproduced.

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  • Control and Information Processing Functions using Chaotic Dynamics in Neural Network Model and Cellular Automata

    Grant number:16500131  2004 - 2006

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    NARA Shigetoshi, NAGAYA Tomoyuki, KUROIWA Jousuke, NISHIKAWA Takeshi

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    Grant amount:\3400000 ( Direct expense: \3400000 )

    It is shown that complex dynamics including chaos can be useful in realizing of complex functions and complex control by means of simple rule (s) . The two computer experiments have been done. One is to use a neural network model and the other is to use cellular automata The former enables us to understand a possible mechanism of memory dynamics in brain and excellent control observed in biological control. The latter enables us not only to analyze complexity contained in sound signal, music and voices, but also to compress data in completely reversible way. Using the neural network model, computer experiment to solve two-dimensional maze which is set as a typical ill-posed problem was done. The performance is evaluated by numerical methods. A plan of hardware implementation is proposed. All works were reported in conference meetings and were submitted to several scientific or engineering journals.

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  • Observation of One-dimensional Spinodal Decomposition in a Liquid Crystal

    Grant number:15540371  2003 - 2004

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    NAGAYA Tomoyuki, NARA Shigetoshi, NISHIKAWA Takeshi

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    Grant amount:\3600000 ( Direct expense: \3600000 )

    The zigzag instability coarsening of a splay-bend wall formed in a nematic liquid crystal under external fields is investigated experimentally as a study of a one-dimensional analog of the spinodal decomposition in a conserved order parameter system. When an electric field is applied on the liquid crystal, a sinusoidal modulation first appears, then the shape of wall changes to zigzag. In the late stage, the coarsening of zigzag vertexes proceeds due to the coalescence of zigzag vertexes.
    1.In the late stage of coarsening, a characteristic length, i.e.the mean width of the zigzag period, shows logarithmic increase in time, which agrees with the theoretical prediction.
    2.The structure function and the correlation function for the Ising domain and the density correlation of zinzag vertexes are analyzed. Then it is clarified that the dynamical scaling law holds in the late stage of coarsening.
    3.The kink-antikink kinetics of one-dimensional phase ordering is studied numerically. The logarithmic growth of the mean width of domains is also confirmed. The distribution of domain size and the correlation function are shown to satisfy a scaling relation. The two-time autocorrelation function follows a power law whose exponent depends on the start time of the calculation.
    4.The time evolution of the sinusoidal modulation in the early stage of coarsening is analyzed experimentally. It is found that the sinusoidal modulation develops exponentially up to an equilibrium value as expected in the theory of spinodal decomposition. Basing our study on the linear stability analysis of the splay-bend wall equation of motion, the growth rate of the sinusoidal modulation is discussed. In the vicinity of the zigzag instability, the experimental result agrees with the prediction form the linear stability analysis.

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  • Ion Cluster Model for Super-Dense Plasmas

    Grant number:07680508  1995 - 1996

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    FURUTANI Yoichiro, TKABE Hideaki, NISHIKAWA Takeshi, FUKUYAMA Atsushi, TOTSUJI Hiroo

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    Grant amount:\1200000 ( Direct expense: \1200000 )

    With recourse to the Thomas-Fermi-Dirac-Weizasacker (TFDW) statistical model of atoms, based on the Density Functional Theory (DFT), we have carried out numerical analysis of the internal structure of compressed atoms, diatomic and triatomic molecules, the smallest candidates for the ion cluster, immersed in such dense matters as a laser-imploded plasma.
    1. DFT for compressed diatomic molecules
    Substituting as an initial input the effective potential for a diatomic molecule into the potential-energy term of the two-dimensional Kohn-Sham equation and coupling it with Poisson's equation, we solve them by iterative method to obtain the one-electron state (DFT). We have concentrated only to the analytical aspect of the problem, expounded in the attached research report. As for numerical analysis, a relevant code is not completely explored yet, so that no numerical result is available at present.
    2. Formulation of the triatomic molecule
    With regards the ion cluster model, we have formulated the problem of the triatomic molecule, considered as the smallest example of the ion cluster, the content of which we present in the attached research report. Since the triatomic molecule loses whatsoever symmetry, numerical analysis turns out to be three-dimensional. Though a formal extension of the two-dimensional code to the three-dimensional one within the free-boundary finite difference scheme is straightforward, the latter code can not be handled by Workstation of our group. We envisage a tight collaboration with the theoretical group of ILE (Osaka University) which disposes of a high-quality supercomputer.
    3. Analysis of the two-temperature model of heavy atoms
    As was already explained in the brief report of the 1996 fiscal year, the two-temperature model is a model out of equilibrium, composed of closed shells at their ground state and the peripheral clad electron gas at finite temperatures. After the presentation, with success, at the 12th International Conference on Laser Interaction and Related Plasma Phenomena on April 1995, the reults was published in J.PHys.Soc.Jpn. (Vol.65, No.8, pp.2463-2471).
    4. Analysis of the Thomas-Fermi (TF) atom in super-intense magnetic fields
    It is conjectured that there exist super-intense magnetic fields of the order of 10^<12> to 10^<14> Gausss on pulsar surfaces and of the order of 10^6 to 10^8 Gauss on the surface of a laser-imploded plasma due to the anisotropic compression. We have carried out numerical analysis of the internal structure of spherically symmetric TF atoms at their ground stae, subject to such super-intense magnetic fields. Extention of the TF to the TFDW atoms, by inclusion of the gradient correction of the elctron density and of the exchange-correlation potentials, is now in progress. A solution of the Kohn-Sham equation applied to a strongly magnetized TFDW atoms is also envisaged in view of distinguishing spherical from non-spherical atomic shapes.

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  • レーザー生成高ZプラズマからのX線輻射輸送に関する理論的研究

    Grant number:05780359  1993

    日本学術振興会  科学研究費助成事業  奨励研究(A)

    西川 亘

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    Grant amount:\900000 ( Direct expense: \900000 )

    ハートリー・フォック・スレーターモデル(HFS)を用いて、レーザー照射によって生成されたプラズマ中に存在する部分電離高Zイオンのエネルギー凖位と振動子強度を計算するコードを作成した。従来の流体コード中で用いられている放射、吸収係数を計算した原子モデルのうち、金プラズマの束縛-束縛遷移の遷移エネルギーと振動子強度について、HFSモデルの計算結果と比較した。
    束縛-束縛過程の遷移エネルギーについては、流体コード中で用いられている簡単なPerrotのモデルでも最大で15%程度の違いに収まることがわかった。しかしながら、金などの高Zイオンでは内部量子数(j)が違うことによるエネルギー凖位の分離が無視できないほど大きいことがわかった。主量子数と方位量子数で分けた従来のモデルで得られるエネルギー凖位は、実際には内部量子数の違う2つのエネルギー凖位に分かれ、その結果、従来のモデルでは含めることのできていない束縛-束縛遷移があることがわかった。現在その効果を入れた平均イオンモデルを作成中である。
    吸収振動子強度は同じ殻の束縛電子の電子数が変化しても単調な変化をし、従来の流体コード中で用いられているモデルでは開殻の電子数が少ないイオンではよく一致していることを確認した。しかしながら、殻の電子数が変化しても同じ値を用いているため、殻に電子がほとんど詰まっている閉殻に近い状態では、正確な値からの差が拡大し、最大100%程度の違いがあることがわかった。特に、低電離プラズマのシミュレーションをする場合にはこの傾向は大きくなり改善する必要があることがわかった。

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  • 半古典近似を用いた原子モデル

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    Grant type:Competitive

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  • オパシティーの理論・数値計算に関する研究

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    Grant type:Competitive

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  • Atomic Modeling based on semi-classical theory

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  • Study on theory and numerical calulation of Opacity

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    Grant type:Competitive

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