Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yogo, Akifumi*; Bulanov, S. V.; Mori, Michiaki; Ogura, Koichi; Esirkepov, T. Z.; Pirozhkov, A. S.; Kanasaki, Masato*; Sakaki, Hironao; Fukuda, Yuji; Bolton, P.; et al.
Plasma Physics and Controlled Fusion, 58(2), p.025003_1 - 025003_7, 2016/02
Times Cited Count：9 Percentile：46.03(Physics, Fluids & Plasmas)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：62.3(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.
Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya*; Sakaki, Hironao; Hori, Toshihiko*; Ogura, Koichi; Nishiuchi, Mamiko; Teshima, Teruki*; Nishimura, Hiroaki*; et al.
Japanese Journal of Applied Physics, 50(10), p.106401_1 - 106401_7, 2011/10
Times Cited Count：8 Percentile：34.67(Physics, Applied)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：19 Percentile：66.78(Optics)
line emission from Mo and Ag plate were experimentally studied by using ultra-high intensity, clean femtosecond laser pulses. Absolutely yield of 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 yields were obtained for both Mo and Ag with higher contrast ratios and high irradiance. The conversion efficiencies of 4.28 
10
/sr for Mo and 4.84 10/sr for Ag, the highest values ever obtained, have been demonstarted with the contrast ratio of 10
to 10
.
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 10/sr, the highest value ever obtained, has been demonstrated at 5.5 10
W/cm
with a contrast ratio of 10.
Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Kawase, Keigo; Bulanov, S. V.; Ogura, Koichi; Pirozhkov, A. S.; Kondo, Kiminori; Sugiyama, Akira; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.4062 - 4064, 2010/05
Azuma, Hirozumi*; Sagisaka, Akito; Daido, Hiroyuki; Ito, Isao*; Kadoura, Hiroaki*; Kamiya, Nobuo*; Ito, Tadashi*; Nishimura, Akihiko; Ma, J.*; Mori, Michiaki; et al.
Applied Surface Science, 255(24), p.9783 - 9786, 2009/09
Times Cited Count：2 Percentile：11.75(Chemistry, Physical)Commercial single crystal silicon wafers and amorphous silicon films piled on single crystal silicon wafers were irradiated with a femtosecond pulsed laser and a nanosecond pulsed laser at irradiation intensities between 10
W/cm and 10
W/cm. In the single crystal silicon substrate, the irradiated area was changed to polycrystalline silicon and the piled silicon around the irradiated area has spindly column structures constructed of polycrystalline and amorphous silicon. In particular, in the case of the higher irradiation intensity of 10 W/cm, the irradiated area was oriented to the same crystal direction as the substrate. In the case of the lower irradiation intensity of 10
W/cm, only amorphous silicon was observed around the irradiated area, even when the target was single crystal silicon.
Mori, Michiaki; Kondo, Kiminori; Mizuta, Yoshio*; Kando, Masaki; Kotaki, Hideyuki; Nishiuchi, Mamiko; Kado, Masataka; Pirozhkov, A. S.; Ogura, Koichi; Sugiyama, Hironori*; et al.
Physical Review Special Topics; Accelerators and Beams, 12(8), p.082801_1 - 082801_5, 2009/08
Times Cited Count：23 Percentile：77.92(Physics, Nuclear)The pointing stability and divergence of a quasimonoenergetic electron bunch generated in a self-injected laser-plasma acceleration regime using 4 TW laser is studied. A pointing stability of 2.4 mrad root-mean-square (RMS) and a beam divergence of 10.6 mrad (RMS) were obtained using an argon gas-jet target for 50 sequential shots, while these values were degraded by a factor of three at the optimum condition using helium. The peak electron energies were 8.5
0.7 MeV and 24.83.6 MeV using argon and helium, respectively. The experimental results indicate that the different propagation condition could be generated with the different material, although it is performed with the same irradiation condition.
Mori, Michiaki; Mizuta, Yoshio*; Kondo, Kiminori; Nishiuchi, Mamiko; Kado, Masataka; Kando, Masaki; Pirozhkov, A. S.; Kotaki, Hideyuki; Ogura, Koichi; Sugiyama, Hironori*; et al.
no journal, ,
The collimatability of quasi-monoenergetic electron beam production in the self-injected laser-plasma acceleration regime is studied. The collimation of electron beam drived by terawatt femtosecond laser (4.1 TW, 40 fs) is measured at two species of gas material (Helium gasjet and Argon gasjet). We measured 3.2 mrad pointing stability and beam divergence of 11 mrad (r.m.s.) at Argon gasjet for 50 sequencial shots. At such condition, the peak electron energy is 9.11.0 MeV with 80% reproducebility. For Helium, the pointing stability is three times larger than that of Argon. It is considered that the laser channel formation is important role for stable electron beam generation.
Mori, Michiaki; Mizuta, Yoshio*; Kondo, Kiminori; Nishiuchi, Mamiko; Kado, Masataka; Kando, Masaki; Pirozhkov, A. S.; Kotaki, Hideyuki; Ogura, Koichi; Sugiyama, Hironori*; et al.
no journal, ,
The stability and collimatability of quasi-monoenergetic electron beam production in the self-injected laser-plasma acceleration regime are studied. The collimation of electron beam drived by terawatt femtosecond laser (4.5 TW, 40 fs) is measured at two species of gas material (Helium gasjet and Argon gasjet). We measured 3.2 mrad pointing stability and beam divergence of 11 mrad (r.m.s.) at Argon gasjet for 50 continuous shots. At such condition, the peak electron energy is 9.11.6 MeV. For Helium, the pointing stability is three times larger than that of Argon. It is considered that the laser channel formation is important role for stable electron beam generation.
Mori, Michiaki; Ogura, Koichi; Yogo, Akifumi; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Pirozhkov, A. S.; Sagisaka, Akito; Orimo, Satoshi; Tampo, Motonobu; Daito, Izuru; et al.
no journal, ,
Experimental studies of laser-driven ion acceleration aimed at ion therapy for cancer treatment are being conducted at the PMRC of JAEA using the J-KAREN Ti:Sapphire laser system at JAEA's APRC. In recent experiments thin foil targets have been irradiated with focused 38 fs laser pulses at the 1.8J laser energy. The energy spectrum of the proton beam is observed to extend to a cut-off value in excess of 7-MeV. Our results expose the prospects and challenges associated with developing a laser-driven ion therapy facility.
Nishiuchi, Mamiko; Ogura, Koichi; Sagisaka, Akito; Yogo, Akifumi; Pirozhkov, A. S.; Mori, Michiaki; Kiriyama, Hiromitsu; Orimo, Satoshi; Tampo, Motonobu; Daito, Izuru; et al.
no journal, ,
no abstracts in English
Mori, Michiaki; Ogura, Koichi; Yogo, Akifumi; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Pirozhkov, A. S.; Sagisaka, Akito; Orimo, Satoshi; Tampo, Motonobu; Daito, Izuru; et al.
no journal, ,
no abstracts in English
Yogo, Akifumi; Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya; Mori, Michiaki; Ogura, Koichi; Orimo, Satoshi; et al.
no journal, ,
no abstracts in English
Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya; Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Mori, Michiaki; Ogura, Koichi; Orimo, Satoshi; et al.
no journal, ,
no abstracts in English
Mori, Michiaki; Kotaki, Hideyuki; Kawase, Keigo; Hayashi, Yukio; Kando, Masaki; Ogura, Koichi; Kondo, Kiminori; Bulanov, S. V.; Nishimura, Hiroaki*; Yokoyama, Atsushi
no journal, ,
no abstracts in English
Mori, Michiaki; Kotaki, Hideyuki; Hayashi, Yukio; Kando, Masaki; Bulanov, S. V.; Ogura, Koichi; Pirozhkov, A. S.; Kondo, Kiminori; Nishimura, Hiroaki*; Sugiyama, Akira
no journal, ,
Density-ramp injection is one of methods to generate high quality sub-MeV class electron bunch. From LBL group, the transverse energy spread of 
p/p=0.026 was obtained at 400 keV class quasi-monoenergetic electron bunches driven by 10-TW laser and short-focus optical configuration. In particular, since long-focus configuration provides lower electric field gradient in the transverse direction, and it can be generate low transverse energy spreaded electron bunch. In this work, we studied on sub-MeV class electron bunch generation driven by 3-TW laser and long-focus configuration. We obtained transverse momentum spread of p/p=0.016 at 200 keV at 200 keV class quasi-monoenergetic electron bunches. This experimental result reveals momentum spread in the transverse direction is suppressed by the long-focus configurations.
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
Mori, Michiaki; Kotaki, Hideyuki; Kando, Masaki; Hayashi, Yukio; Koga, J. K.; Bulanov, S. V.; Pirozhkov, A. S.; Ogura, Koichi; Kondo, Kiminori; Nishimura, Hiroaki*; et al.
no journal, ,
We obtained low transverse momentum spread ( ptrans/p= 1.610
) electron bunch from 500 
m-scale rare gas target using 2-TW laser beam with long-focus configuration. This value is 2/3 times lower than that from LBL result. In particular, we obtained energy boosting from sub-MeV to 30-MeV class by the multi-stage acceleration. We would like to report on the experimental result mainly.
Sagisaka, Akito; Ogura, Koichi; Nishikino, Masaharu; Pirozhkov, A. S.; Kawachi, Tetsuya; Nishiuchi, Mamiko; Kando, Masaki; Kondo, Kiminori; Arikawa, Yasunobu*; Kojima, Sadaoki*; et al.
no journal, ,
High-intensity laser and thin-foil interactions produce high-energy particles and hard X-ray. A proton beam driven by a high-intensity laser has received attention as a ion source for medical and other applications. We have performed high energy laser-matter interaction experiments using a thin-foil target irradiated by LFEX laser at Osaka University. The three beams were focused at a thin-foil target. The maximum proton energy of 
40 MeV energy were observed at the total laser energy of 700 J. The preliminary experiment for plasma mirror are started.
