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Journal Articles

Laser wakefield accelerated electron beam monitoring and control

Koga, J. K.; Mori, Michiaki; Kotaki, Hideyuki; Bulanov, S. V.; Esirkepov, T. Z.; Kiriyama, Hiromitsu; Kando, Masaki

AIP Conference Proceedings 1721, p.050003_1 - 050003_8, 2016/03

Journal Articles

Ion acceleration via "nonlinear vacuum heating" by the laser pulse obliquely incident on a thin foil target

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:4 Percentile:63.7(Physics, Fluids & Plasmas)

Journal Articles

Status and upgrade plan of the cERL gun

Nishimori, Nobuyuki; Nagai, Ryoji; Mori, Michiaki; Hajima, Ryoichi; Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Uchiyama, Takashi*; Jin, X.*; Obina, Takashi*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.511 - 515, 2015/09

no abstracts in English

Journal Articles

Demonstration of laser Compton-scattered photon source at the cERL

Nagai, Ryoji; Hajima, Ryoichi; Shizuma, Toshiyuki; Mori, Michiaki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Araki, Sakae*; Terunuma, Nobuhiro*; Urakawa, Junji*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1328 - 1330, 2015/09

Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 $$^{circ}$$, respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm$$^{2}$$ placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200/s, 6.91 keV, and 81 eV, respectively.

Journal Articles

Direct observation of the pulse width of an ultrashort electron beam

Kotaki, Hideyuki; Kawase, Keigo*; Hayashi, Yukio; Mori, Michiaki; Kando, Masaki; Koga, J. K.; Bulanov, S. V.

Journal of the Physical Society of Japan, 84(7), p.074501_1 - 074501_5, 2015/07

 Times Cited Count:5 Percentile:49.53(Physics, Multidisciplinary)

Journal Articles

Yb:YAG thin-disk chirped pulse amplification laser system for intense terahertz pulse generation

Ochi, Yoshihiro; Nagashima, Keisuke; Maruyama, Momoko; Tsubouchi, Masaaki; Yoshida, Fumiko; Kono, Nanase; Mori, Michiaki; Sugiyama, Akira

Optics Express (Internet), 23(11), p.15057 - 15064, 2015/06

 Times Cited Count:18 Percentile:18.36(Optics)

We have developed a 1 kHz repetition picosecond laser system dedicated for intense terahertz (THz) pulse generation. The system comprises a chirped pulse amplification laser equipped with a Yb:YAG thin-disk amplifier. At room temperature, the Yb:YAG thin-disk regenerative amplifier provides pulses having energy of over 10 mJ and spectral bandwidth of 1.2 nm. The pulse duration achieved after passage through a diffraction grating pair compressor was 1.3 ps. By employing this picosecond laser as a pump source, THz pulses having a peak frequency of 0.3 THz and 4 $$mu$$J of energy were generated by means of optical rectification in an Mg-doped LiNbO$$_{3}$$ crystal.

Journal Articles

Demonstration of high-flux photon generation from an ERL-based laser Compton photon source

Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Araki, Sakae*; Honda, Yosuke*; Kosuge, Atsushi*; Terunuma, Nobuhiro*; Urakawa, Junji*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1607 - 1609, 2015/06

Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 deg., respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm$$^{2}$$ placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200 /s, 6.91 keV, and 81 eV, respectively.

Journal Articles

High-contrast, high-intensity petawatt-class laser and applications

Kiriyama, Hiromitsu; Mori, Michiaki; Pirozhkov, A. S.; Ogura, Koichi; Sagisaka, Akito; Kon, Akira; Esirkepov, T. Z.; Hayashi, Yukio; Kotaki, Hideyuki; Kanasaki, Masato*; et al.

IEEE Journal of Selected Topics in Quantum Electronics, 21(1), p.1601118_1 - 1601118_18, 2015/01

 Times Cited Count:46 Percentile:3.04(Engineering, Electrical & Electronic)

This paper reviews the development of a high-contrast high-intensity petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser for research on high field science. We discuss in detail the design, performance and characterization of the laser. We also describe the on-going upgrade of the laser system and some applications for the laser in relativistic dominated laser-matter interactions.

Journal Articles

Status of $$gamma$$-ray nondestructive assay by laser Compton scattered source

Hajima, Ryoichi; Shizuma, Toshiyuki; Nagai, Ryoji; Mori, Michiaki; Hayakawa, Takehito; Angell, C.; Seya, Michio

Kaku Busshitsu Kanri Gakkai (INMM) Nippon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 7 Pages, 2015/01

no abstracts in English

Journal Articles

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; Koga, J. K.; Mori, Michiaki; Kawase, Keigo*; et al.

RAL-TR-2015-025, P. 22, 2015/00

Journal Articles

Construction of the equipment for a demonstration of laser Compton-scattered photon source at the cERL

Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1328 - 1331, 2014/10

A high intensity $$gamma$$-ray source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. A beamline and an experimental hatch are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015.

Journal Articles

Development of the beamline flux monitor for the laser Compton-scattered photon source

Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Urakawa, Junji*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.839 - 842, 2014/10

In order to demonstrate accelerator and laser technologies required for a laser Compton scattering (LCS) photon generation, a LCS photon source is under construction at the Compact ERL (cERL). We considered the flux monitors for the adjustment LCS photon source. A thin scintillator detector and a silicon drift detector are employed as flux monitors and are installed at the upstream part of the LCS beamline. The background signal level due to the bremsstrahlung of the electron beam was measured by a CsI(pure) scintillator. In the result of the measurement, the background signal is acceptable level for the flux monitors.

Journal Articles

Current status of the driver laser system for intense terahertz wave generation

Tanaka, Momoko; Ochi, Yoshihiro; Kosuge, Atsushi; Okada, Hajime; Mori, Michiaki; Kiriyama, Hiromitsu; Tsubouchi, Masaaki; Nagashima, Keisuke

JAEA-Conf 2014-001, p.32 - 33, 2014/09

We have constructed a high power kHz laser system using Yb:YAG thin-disk as a gain medium for a driver laser of THz wave generation. A 4-bounce regenerative amplifier is constructed and output energy up to 10 mJ is obtained. Using compressed pulse, we demonstrated THz wave generation with LiNbO$$_{3}$$ crystal.

Journal Articles

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; et al.

New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09

 Times Cited Count:20 Percentile:19.6(Physics, Multidisciplinary)

Journal Articles

Construction of a laser Compton scattered photon source at cERL

Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Honda, Yosuke*; Kosuge, Atsushi*; Urakawa, Junji*

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1940 - 1942, 2014/07

In order to demonstrate required accelerator and laser technologies for a high intensity $$gamma$$-ray source from the laser Compton scattering (LCS), an LCS photon source and the peripheral equipment are under construction at the Compact ERL (cERL) at High Energy Accelerator Research Organization (KEK). The LCS photon source by an electron beam in the energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear species. The LCS photon source and the peripheral equipment consist of a mode-locked fiber laser, laser enhancement cavity, beamline, and experimental hatch. The commissioning of the LCS photon source will be started in February 2015.

Journal Articles

High power laser developments with femtosecond to nanosecond pulse durations for laser shock science and engineering

Kiriyama, Hiromitsu; Mori, Michiaki; Suzuki, Masayuki*; Daito, Izuru*; Okada, Hajime; Ochi, Yoshihiro; Tanaka, Momoko; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; et al.

Reza Kenkyu, 42(6), p.441 - 447, 2014/06

We describe three specific high power laser systems that are being developed in our laboratory for many applications in high field science, nonlinear optics and material processing. We report on a femtosecond petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 20 J of 40 fs pulse duration, a picosecond high intensity Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 mJ of 0.5 ps pulse duration, and a nanosecond high repetition rate Nd:YAG laser system that can provide an average power of 360 W with a pulse duration of 30 ns delivered at a 1 kHz repetition rate. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.

Journal Articles

Application of laser Compton scattered $$gamma$$-ray beams to nondestructive detection and assay of nuclear material

Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Angell, C.; Nagai, Ryoji; Nishimori, Nobuyuki; Sawamura, Masaru; Matsuba, Shunya; Kosuge, Atsushi*; Mori, Michiaki; et al.

European Physical Journal; Special Topics, 223(6), p.1229 - 1236, 2014/05

 Times Cited Count:11 Percentile:54.32(Physics, Multidisciplinary)

Journal Articles

Current status and future prospects of "J-KAREN"; High contrast, high intensity laser for studying relativistic laser-matter interactions

Kiriyama, Hiromitsu; Mori, Michiaki; Okada, Hajime; Shimomura, Takuya; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Yogo, Akifumi; Sagisaka, Akito; et al.

JPS Conference Proceedings (Internet), 1, p.015095_1 - 015095_5, 2014/03

We present the design and characterization of a high-contrast, petawatt-class Ti:sapphire chirped-pulse amplification (CPA) laser system. Two saturable absorbers and low-gain optical parametric chirped-pulse amplification (OPCPA) preamplifier in the double CPA laser chain have improved the temporal contrast to 1.4$$times$$10$$^{12}$$ on the subnanosecond time scale at 70 terawatt level. Final uncompressed broadband pulse energy is 28 J, indicating the potential for reaching peak power near 600 terawatt. We also discuss our upgrade to over petawatt level at a 0.1 Hz repetition rate briefly.

Journal Articles

Minimum condition of target gas material at an ionization-stage control scheme in a laser-plasma electron acceleration

Mori, Michiaki; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Kiriyama, Hiromitsu; Okada, Hajime; Pirozhkov, A. S.; Bulanov, S. V.; Kondo, Kiminori; Bolton, P.

JPS Conference Proceedings (Internet), 1, p.015094_1 - 015094_6, 2014/03

We report on the appropriate and inappropriate gas materials to generate energetic electrons. The 4-TW peak power and 40-fs pulse duration laser beam illuminated the gas-jet target with intensity of 9$$times$$10$$^{17}$$W/cm$$^{2}$$ measured in vacuum. We investigated energetic electron beam generation using neon and argon. Energetic electron beam was observed in argon at the lowest neutral gas density of 5$$times$$10$$^{18}$$cm$$^{-3}$$. However, no energetic electrons ($$>$$ 1 MeV, $$>$$ 1 pC) were observed in neon although neutral gas density is increased from5$$times$$10$$^{18}$$cm$$^{-3}$$ to 5$$times$$10$$^{19}$$cm$$^{-3}$$. By considering ionization stage at such an intensity, the maximum plasma density is reached to be a quarter critical plasma density, at which the maximum growth-rate of laser-plasma instability is expected. On the other hand, propagation of the pumping laser was observed in neon and argon by using optical probing. Significantly different images were observed. The structure of the laser channel for energetic electron beam generation that observed in argon was absent in neon. These results imply that the additional increase of the plasma density due to ionization cannot explain the electron generation. The analysis including the propagation of a laser in ionizing gas would be necessary.

Journal Articles

Polarization-selectable cavity locking method for generation of laser Compton scattered $$gamma$$-rays

Kosuge, Atsushi; Mori, Michiaki; Okada, Hajime; Hajima, Ryoichi; Nagashima, Keisuke

Optics Express (Internet), 22(6), p.6613 - 6619, 2014/03

 Times Cited Count:2 Percentile:82.35(Optics)

Nowadays, generation of energy-tunable, monochromatic $$gamma$$-rays is needed to establish a nondestructive assay method of nuclear fuel materials. The $$gamma$$-rays are generated by collision of laser photons stored in a cavity and relativistic electrons. We propose a configuration of an enhancement cavity capable of performing polarization control fabricated by a combination of a four-mirror ring cavity with a small spot inside a cavity and a three-mirror of reflective optics as an image inverter for polarization-selectable $$gamma$$-rays. The image inverter introduces a phase shift of specific polarization which can be used to generate an error signal to lock an optical cavity at a resonance condition.

311 (Records 1-20 displayed on this page)