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Journal Articles

Temporal behavior of unresolved transition array emission in water window soft X-ray spectral region from multiply charged ions

Dinh, T.-H.*; Suzuki, Yuhei*; Arai, Goki*; Li, B.*; Dunne, P.*; O'Sullivan, G.*; Fujioka, Shinsuke*; Hasegawa, Noboru; Kawachi, Tetsuya; Nishikino, Masaharu; et al.

Applied Physics Letters, 107(12), p.121101_1 - 121101_5, 2015/09

 Times Cited Count:5 Percentile:25.53(Physics, Applied)

Journal Articles

Density and X-ray emission profile relationships in highly ionized high-Z laser-produced plasmas

Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; Hirose, Ryoichi*; et al.

Applied Physics Letters, 106(12), p.121109_1 - 121109_5, 2015/03

 Times Cited Count:6 Percentile:29.98(Physics, Applied)

Journal Articles

Efficient extreme ultraviolet emission from one-dimensional spherical plasmas produced by multiple lasers

Yoshida, Kensuke*; Fujioka, Shinsuke*; Higashiguchi, Takeshi*; Ugomori, Teruyuki*; Tanaka, Nozomi*; Ohashi, Hayato*; Kawasaki, Masato*; Suzuki, Yuhei*; Suzuki, Chihiro*; Tomita, Kentaro*; et al.

Applied Physics Express, 7(8), p.086202_1 - 086202_4, 2014/08

 Times Cited Count:25 Percentile:73.69(Physics, Applied)

We demonstrate high conversion efficiency for extreme ultraviolet (EUV) emission at 6.5-6.7 nm from multiple laser beam-produced one-dimensional spherical plasmas. Multiply charged-state ions produce strong resonance emission lines, which combine to yield intense unresolved transition arrays in Gd, Tb, and Mo. The maximum in-band EUV conversion efficiency was observed to be 0.8%, which is one of the highest values ever reported due to the reduction of plasma expansion loss.

Journal Articles

A View of technology maturity assessment to realize fusion reactor by Japanese young researchers

Kasada, Ryuta*; Goto, Takuya*; Fujioka, Shinsuke*; Hiwatari, Ryoji*; Oyama, Naoyuki; Tanigawa, Hiroyasu; Miyazawa, Junichi*; Young Scientists Special Interest Group on Fusion Reactor Realization*

Purazuma, Kaku Yugo Gakkai-Shi, 89(4), p.193 - 198, 2013/04

Japanese young researchers who have interest in realizing fusion reactor have analyzed Technology Readiness Levels (TRL) in Young Scientists Special Interest Group on Fusion Reactor Realization. In this report, brief introduction to TRL assessment and a view of TRL assessment against fusion reactor projects conducting in Japan.

Journal Articles

Quantitative measurement of hard X-ray spectra for high intensity laser produced plasma

Zhang, Z.*; Nishimura, Hiroaki*; Namimoto, Takura*; Fujioka, Shinsuke*; Arikawa, Yasunobu*; Nishikino, Masaharu; Kawachi, Tetsuya; Sagisaka, Akito; Hosoda, Hirokazu*; Orimo, Satoshi; et al.

Review of Scientific Instruments, 83(5), p.053502_1 - 053502_5, 2012/05

 Times Cited Count:18 Percentile:65.08(Instruments & Instrumentation)

X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was calibrated using pre-characterized laser-produced X-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for X-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency for specific X-ray line emissions, is derived as a consequence of this work.

Journal Articles

Efficient multi-keV X-ray generation from a high-Z target irradiated with a clean ultra-short laser pulse

Zhang, Z.*; Nishikino, Masaharu; Nishimura, Hiroaki*; Kawachi, Tetsuya; Pirozhkov, A. S.; Sagisaka, Akito; Orimo, Satoshi; Ogura, Koichi; Yogo, Akifumi; Okano, Yasuaki*; et al.

Optics Express (Internet), 19(5), p.4560 - 4565, 2011/02

 Times Cited Count:17 Percentile:65.28(Optics)

$$Kalpha$$ line emission from Mo and Ag plate were experimentally studied by using ultra-high intensity, clean femtosecond laser pulses. Absolutely yield of $$Kalpha$$ X-rays at 17 keV from Mo and 22 keV from Ag were measured as a function of the laser pulse contrast ratio and irradiation intensity. Significant enhancement of $$Kalpha$$ yields were obtained for both Mo and Ag with higher contrast ratios and high irradiance. The conversion efficiencies of 4.28 $$times$$ 10$$^{-5}$$/sr for Mo and 4.84 $$times$$ 10$$^{-5}$$/sr for Ag, the highest values ever obtained, have been demonstarted with the contrast ratio of 10$$^{-10}$$ to 10$$^{-11}$$.

Journal Articles

Monochromatic X-ray emission from laser produced plasma with a clean ultra-short laser pulse

Zhang, Z.*; Nishikino, Masaharu; Nishimura, Hiroaki*; Kawachi, Tetsuya; Sagisaka, Akito; Orimo, Satoshi; Ogura, Koichi; Pirozhkov, A. S.; Yogo, Akifumi; Okano, Yasuaki*; et al.

Reza Kenkyu, 38(9), p.698 - 701, 2010/09

Monochromatic X-ray generation from Cu plates was experimentally studied by using a high contrast femtosecond laser pulse. Absolute yield of Ka line at 8 keV was measured as a function of laser pulse contrast ration and irradiation intensity. The conversion efficiency of 8 $$times$$ 10$$^{-5}$$/sr, the highest value ever obtained, has been demonstrated at 5.5 $$times$$ 10$$^{16}$$ W/cm$$^{2}$$ with a contrast ratio of 10$$^{-11}$$.

Journal Articles

Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

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

Journal of Applied Physics, 107(11), p.113303_1 - 113303_11, 2010/06

 Times Cited Count:35 Percentile:77.43(Physics, Applied)

Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. An atomic model of Sn is developed on the basis of calculated atomic data using the Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions are identified. The wavelengths of the 4$$d$$-4$$f$$ + 4$$p$$-4$$d$$ transitions of Sn$$^{5+}$$ to Sn$$^{13+}$$ are investigated. Results of calculation are compared with those of the charge exchange spectroscopy, measurement of the emission spectrum of the laser produced plasma EUV source, and the opacity measurement of a radiatively heated Sn sample. A reasonable agreement is observed between calculated and experimental EUV emission spectra. The spectral emissivity and opacity of Sn plasmas are calculated using a full collisional radiative (CR) model as a function of electron temperature and ion density.

Journal Articles

Complementary spectroscopy of tin ions using ion and electron beams

Ohashi, Hayato*; Suda, Shintaro*; Tanuma, Hajime*; Fujioka, Shinsuke*; Nishimura, Hiroaki*; Nishihara, Katsunobu*; Kai, Takeshi; Sasaki, Akira; Sakaue, Hiroyuki*; Nakamura, Nobuyuki*; et al.

Journal of Physics; Conference Series, 163, p.012071_1 - 012071_4, 2009/06

 Times Cited Count:7 Percentile:89.79

Extreme ultra-violet (EUV) emission spectra of multiply charged tin ions were measured in the wavelength range of 10-22 nm following charge exchange collisions or the electron impact excitation of tin ions. In charge exchange collisions, we observed both the resonance lines and the emission lines corresponding to the transitions between the excited states. On the other hand, we observed mainly the resonance lines in the electron impact experiments. We can distinguish the resonance lines from other emission lines in the charge exchange spectrum by comparison with the emission lines in the electron impact spectrum.

Journal Articles

Atomic model and optimization of EUV light source

Nishihara, Katsunobu*; Sunahara, Atsushi*; Sasaki, Akira; Tanuma, Hajime*; Koike, Fumihiro*; Fujioka, Shinsuke*; Nishimura, Hiroaki*; Shimada, Yoshinori*

Reza Kenkyu, 36(11), p.690 - 699, 2008/11

The critical issue for realization of a laser produced plasma (LPP) extreme ultraviolet (EUV) light source is the conversion efficiency (CE) from incident laser power to EUV radiation of 13.5 nm wavelength. From an atomic physics, we show that tin is the most suitable radiation material compared with xenon and lithium. We also show the optimization of laser and target conditions to obtain high CE using a power balance model. We propose a double-pulse irradiation scheme for high CE using a carbon dioxides laser and a droplet target.

Journal Articles

EUV light source by high power laser

Izawa, Yasukazu*; Nishihara, Katsunobu*; Tanuma, Hajime*; Sasaki, Akira; Murakami, Masakatsu*; Sunahara, Atsushi*; Nishimura, Hiroaki*; Fujioka, Shinsuke*; Aota, Tatsuya*; Shimada, Yoshinori*; et al.

Journal of Physics; Conference Series, 112, p.042047_1 - 042047_4, 2008/00

 Times Cited Count:7 Percentile:92.67

In the development of a high power EUV source used in the EUV lithography system, we have been constructed EUV database of laser-produced tin plasma by the theoretical and experimental studies. On the basis of our understanding, the optimum conditions of lasers and plasmas were clarified, and we proposed the guidelines of laser plasma to obtain clean, efficient and high power EUV source for the practical EUV lithography system. In parallel to such studies, novel targets and high power laser system to generate the optimized EUV source plasma have been developed.

Journal Articles

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

Nishihara, Katsunobu*; Sunahara, Atsushi*; Sasaki, Akira; Nunami, Masanori*; Tanuma, Hajime*; Fujioka, Shinsuke*; Shimada, Yoshinori*; Fujima, Kazumi*; Furukawa, Hiroyuki*; Kato, Takako*; et al.

Physics of Plasmas, 15(5), p.056708_1 - 056708_11, 2008/00

 Times Cited Count:110 Percentile:97.36(Physics, Fluids & Plasmas)

Journal Articles

Radiation hydrodynamic simulation of extreme ultra-violet emission from laser-produced tin plasmas

Sunahara, Atsushi*; Sasaki, Akira; Tanuma, Hajime*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Fujioka, Shinsuke*; Aota, Tatsuya*; Yamaura, Michiteru*; Shimada, Yoshinori*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(11), p.920 - 926, 2007/11

We study the EUV emission from laser produced Sn plasmas using the 1D and 2D radiation hydrodynamics simulation, for the development of EUV source for the next generation semiconductor lithography. The opacity and emissivity of the plasma used in the simulation are calculated by a detailed atomic model, with the accurate wavelength of emission lines obtained from the detailed spectroscopic measurements. Calculation is shown to reproduce the experimental spectrum and conversion efficiency reasonably, including the effect of photo pumping which modifies the EUV emission spectrum in the case with a long scale length of the plasmas.

Journal Articles

Low-density tin targets for efficient extreme ultraviolet light emission from laser-produced plasmas

Okuno, Tomoharu*; Fujioka, Shinsuke*; Nishimura, Hiroaki*; Tao, Y.*; Nagai, Keiji*; Gu, Q.*; Ueda, Nobuyoshi*; Ando, Tsuyoshi*; Nishihara, Katsunobu*; Norimatsu, Takayoshi*; et al.

Applied Physics Letters, 88(16), p.161501_1 - 161501_3, 2006/04

 Times Cited Count:63 Percentile:88.08(Physics, Applied)

no abstracts in English

Journal Articles

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

Fujioka, Shinsuke*; Nishimura, Hiroaki*; Nishihara, Katsunobu*; Sasaki, Akira; Sunahara, Atsushi*; Okuno, Tomoharu*; Ueda, Nobuyoshi*; Ando, Tsuyoshi*; Tao, Y.*; Shimada, Yoshinori*; et al.

Physical Review Letters, 95(23), p.235004_1 - 235004_4, 2005/12

 Times Cited Count:140 Percentile:95.51(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

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

Shimada, Yoshinori*; Nishimura, Hiroaki*; Nakai, Mitsuo*; Hashimoto, Kazuhisa*; Yamaura, Michiteru*; Tao, Y.*; Shigemori, Keisuke*; Okuno, Tomoharu*; Nishihara, Katsunobu*; Kawamura, Toru*; et al.

Applied Physics Letters, 86(5), p.051501_1 - 051501_3, 2005/01

 Times Cited Count:110 Percentile:94.52(Physics, Applied)

no abstracts in English

Oral presentation

Monoenergetic hard X-ray emission using ultra-short laser pulses with high contrast

Nishikino, Masaharu; Zhang, Z.*; Nishimura, Hiroaki*; Kawachi, Tetsuya; Pirozhkov, A. S.; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Okano, Yasuaki*; Oshima, Shinsuke*; et al.

no journal, , 

no abstracts in English

Oral presentation

Experimental demonstration of neutron resonance measurement using laser-driven neutron source

Lan, Z.*; Yogo, Akifumi*; Mirfayzi, S. R.*; Hayakawa, Takehito*; Koizumi, Mitsuo; Wei, T.*; Shi, B.*; Ishimoto, Takashi*; Golovin, D.*; Mori, Takato*; et al.

no journal, , 

Oral presentation

Pulsed neutron source and its applications realized by laser

Yogo, Akifumi*; Mirfayzi, S. R.*; Arikawa, Yasunobu*; Abe, Yuki*; Iwamoto, Akihumi*; Hayakawa, Takehito*; Koizumi, Mitsuo; Golovin, D.*; Mori, Takato*; Lan, Z.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Neutron resonance absorption by laser-driven source; Toward "Single Shot" analysis

Yogo, Akifumi*; Lan, Z.*; Hayakawa, Takehito*; Arikawa, Yasunobu*; Abe, Yuki*; Mirfayzi, S. R.*; Koizumi, Mitsuo; Mori, Takato*; Wei, T.*; Fujioka, Shinsuke*; et al.

no journal, , 

no abstracts in English

Oral presentation

The Development of laser-driven epithermal neutron source for resonance spectral diagnostics, 2

Lan, Z.*; Yogo, Akifumi*; Mirfayzi, S. R.*; Koizumi, Mitsuo; Hayakawa, Takehito*; Arikawa, Yasunobu*; Abe, Yuki*; Golovin, D.*; Mori, Takato*; Wei, T.*; et al.

no journal, , 

21 (Records 1-20 displayed on this page)