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Yogo, Akifumi; Daido, Hiroyuki; Bulanov, S. V.; Esirkepov, T. Z.; Nemoto, Koshichi*; Oishi, Yuji*; Nayuki, Takuya*; Fujii, Takashi*; Ogura, Koichi; Orimo, Satoshi; et al.
Journal of Physics; Conference Series, 112, p.042034_1 - 042034_4, 2008/00
Times Cited Count：1 Percentile：55.21(Physics, Fluids & Plasmas)In this work, we present a new method to enhance the proton generation by a 10
-contrast laser. High-energy protons up to 3.8 MeV are observed with 7.5-
m-thick insulator (Polyimide) target irradiated by a laser pulse having energy of 0.8 J and an intensity of 10
-W/cm
. Using two time-of-flight (TOF) spectrometers simultaneously in different directions, we measure the direction dependency of proton-energy spectra. As a result, we find that high-energy component of proton beam is shifted away from the target normal toward the laser-propagation direction, when the laser is focused with 45
incident angle. The TOF measurements over 130 laser shots confirm that the generation of the high-energy protons, which are steered away from the target normal, depends strongly on the laser-focusing condition.
Kotaki, Hideyuki; Daito, Izuru; Hayashi, Yukio; Ma, J.-L.; Chen, L.-M.; Kando, Masaki; Esirkepov, T. Z.; Fukuda, Yuji; Homma, Takayuki; Pirozhkov, A. S.; et al.
Journal of Physics; Conference Series, 112(4), p.042031_1 - 042031_4, 2008/00
Times Cited Count：1 Percentile：55.21(Physics, Fluids & Plasmas)Laser-driven plasma accelerators have been conceived to be the next-generation particle accelerators, promising ultrahigh field particle acceleration with a very short duration electron beam. In the case of electron beam generation by using one laser pulse via wavebreaking, however, it is not stable. In order to generate a stable high-quality electron beam, optical injection by collision of two laser pulses is proposed. Recently, the electron generation with this approach was demonstrated. The experiment was carried out by the perfect head-on collision, which has problems to the backward laser light and the extraction of the generated electron beam. The counter-crossing injection, which is a realistic setup for applications, by two sub-relativistic laser pulses collision with the colliding angle of 45 is demonstrated. The collision of two laser pulses generates a high-quality electron beam with high repeatability. The generated monoenergetic electron beam has 14.4 MeV of the peak energy, 10.6% of the energy spread, 21.8 pC of the charge, 1.6 
mm mrad of the normalized emittance, and 47.4% of the repeatability.
Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*
Journal of Physics; Conference Series, 112, p.042062_1 - 042062_4, 2008/00
Times Cited Count：5 Percentile：84.16(Physics, Fluids & Plasmas)no abstracts in English
Tanaka, Momoko; Furukawa, Hiroyuki*; Murakami, Hidetoshi*; Saito, Shigeki*; Sarukura, Nobuhiko*; Nishikino, Masaharu; Yamatani, Hiroshi; Nagashima, Keisuke; Kagamitani, Yuji*; Ehrentraut, D.*; et al.
Journal of Physics; Conference Series, 112(4), p.042058_1 - 042058_4, 2008/00
Times Cited Count：1 Percentile：55.21(Physics, Fluids & Plasmas)Optical technologies in the extreme ultraviolet (EUV) region have been receiving strong interest for the next generation lithography. Efficient and fast scintillators are one of the key devices functioning in the EUV region. In this paper, we report excellent properties of ZnO and GaN as scintillators in the EUV region, and to demonstrate the feasibility of using a Ni-like Ag EUV laser operated at 13.9-nm to evaluate these properties. The sample was irradiated with EUV laser pulses, and the fluorescence spectrum and the fluorescence lifetime were measured using a streak camera fitted with a spectrograph. In the case of ZnO, a clear, excitonic, fluorescence peak was observed at around 380 nm with a decay lifetime of 3 ns. For GaN, a fluorescence peak at 370 nm having slower 5-ns decay time was observed. In this respect, the EUV scintillation properties of ZnO is said to be more favorable than GaN.
Sunahara, Atsushi*; Sasaki, Akira; Nishihara, Katsunobu*
Journal of Physics; Conference Series, 112, p.042048_1 - 042048_4, 2008/00
Times Cited Count：22 Percentile：98.33(Physics, Fluids & Plasmas)We simulated Extreme Ultra-Violet (EUV) emission from laser-produced tin plasmas for the lithography of semi-conductor, using one- and two- dimensional radiation hydrodynamic simulation codes, and benchmarked the simulations by comparison with recent experiments. We successfully reproduced the measured conversion efficiency, X-ray spectra, and plasma density profiles in the experimental conditions. We found self-absorption of radiation due to the large opacity plays an important role in emission.
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：8 Percentile：93.57(Physics, Fluids & Plasmas)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.
Pirozhkov, A. S.; Esirkepov, T. Z.; Kando, Masaki; Fukuda, Yuji; Ma, J.-L.; Chen, L. M.; Daito, Izuru; Ogura, Koichi; Homma, Takayuki; Hayashi, Yukio; et al.
no journal, ,
Kato, Yoshiaki
no journal, ,
There has been significant progress in laser fusion and high field science in Japan as well as in Asia. The updated status and recent results in these fields will be reviewed. Short-pulse high-power lasers for high field science and high energy lasers for laser fusion are being developed at many laboratories in Asia, stimulating interactions among the Asian and with the Western countries. These activities will help developing understandings on plasma physics at high field and efficient laser drivers that form the bases for laser fusion and high field science. A new program on optical science and technology is being laid out in Japan under MEXT, with which the research on lasers and photonics will be enhanced by forming research networks among the institutes and universities.
