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Journal Articles

Development of technologies of cutting and decontamination employing high power fiber laser

Toyama, Shinichi; Minehara, Eisuke*

Dekomisshoningu Giho, (56), p.55 - 65, 2017/09

Development of the steel cutting technology which employs high power fiber laser for the industrial applicability of the laser technology has been carried out at The Wakasa Wan Energy Research Center (WERC). At present, the laser technologies for dismantling and decontamination are concurrently being developed to the application measure of nuclear dismantling for domestic nuclear power plants in the future. Dismantling of nuclear facilities is now under the development in the world. The necessity of the technology is increasing and the development is strongly expected. Beside the relative easiness to handle compared with other laser system, suppression of production of secondary radioactive waste and dose exposure can be realized by the dramatic improvement by excelled thermal density of fiber laser. This paper provides recent results from cutting technology for thick steels aiming disassembling nuclear pressure vessel, and decontamination machine technology which works under high radiation dose, explaining the results from cutting experiment of steels and the actual equipment and from the radiation resistance experiment for component devices.

Journal Articles

Analytical surveillance of the nuclear waste package processing of the spent ion-exchange resin residuals

Minehara, Eisuke*; Endo, Nobuyuki*

Heisei-23-Nendo Zaidan Hojin Wakasawan Enerugi Kenkyu Senta Nempo, 14, P. 49, 2012/10

no abstracts in English

Journal Articles

Frequency-resolved optical gating system with a tellurium crystal for characterizing free-electron lasers in the wavelength range of 10-30 $$mu$$m

Iijima, Hokuto; Nagai, Ryoji; Nishimori, Nobuyuki; Hajima, Ryoichi; Minehara, Eisuke*

Review of Scientific Instruments, 80(12), p.123106_1 - 123106_5, 2009/12

 Times Cited Count:4 Percentile:71.66(Instruments & Instrumentation)

Journal Articles

Nondestructive detection of hidden chemical compounds with laser Compton-scattering $$gamma$$ rays

Hayakawa, Takehito; Ogaki, Hideaki*; Shizuma, Toshiyuki; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Minehara, Eisuke; Kii, Toshiteru*; Toyokawa, Hiroyuki*

Review of Scientific Instruments, 80(4), p.045110_1 - 045110_5, 2009/04

 Times Cited Count:21 Percentile:24.28(Instruments & Instrumentation)

A non-destructive assay method for measuring a shielded chemical compound has been proposed. The chemical compound is measured by using a nuclear resonance fluorescence (NRF) measurement technique with an energy tunable laser Compton scattering (LCS) $$gamma$$-ray source. This method has an advantage that hidden materials can be detected through heavy shields such as iron plates of a thickness of several centimeters. A detection of a chemical compound of melamine, C$$_{3}$$H$$_{6}$$N$$_{6}$$, shielded by 15-mm-thick iron and 4-mm-thick lead plates is demonstrated. The NRF $$gamma$$-rays of $$^{12}$$C and $$^{14}$$N of the melamine are measured by using the LCS $$gamma$$-rays of the energies of up to 5.0 MeV. The observed ratio ($$^{12}$$C/$$^{14}$$N)$$_{exp}$$ = 0.39 $$pm$$ 0.12 is consistent with (C/N)$$_{melamine}$$ = 0.5.

Journal Articles

Nondestructive detection of heavily shielded materials by using nuclear resonance fluorescence with a laser-Compton scattering $$gamma$$-ray source

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Nishimori, Nobuyuki; Minehara, Eisuke; Hayakawa, Takehito; Shizuma, Toshiyuki; Toyokawa, Hiroyuki*; Ogaki, Hideaki*

Applied Physics Express, 2(3), p.036502_1 - 036502_3, 2009/03

 Times Cited Count:42 Percentile:13.84(Physics, Applied)

Journal Articles

Nondestructive detection and assay of nuclear material by laser Compton $$gamma$$-rays from energy-recovery linacs

Hajima, Ryoichi; Kikuzawa, Nobuhiro; Hayakawa, Takehito; Minehara, Eisuke

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Nondestructive assay of nuclear materials is one of the most urgent research issues for the management of nuclear waste. We apply nuclear resonant fluorescence (NRF), a fingerprint of each isotope, to the nondestructive detection. Detection of NRF signals from objectives irradiated by quasi-monochromatic $$gamma$$-rays enables one to make quantitative assay of nuclear materials in a nondestructive manner. In order to obtain high-flux $$gamma$$-rays for the above purpose, we propose to utilize an energy-recovery linac (ERL), which produces a high-brightness electron beam with high-average current. A design study of high-flux $$gamma$$-ray source based on an ERL shows that a $$gamma$$-ray flux of $$10^{10}$$ ph/sec/keV is obtained and detection of U-238 of 1 Bq/g in a concrete drum is possible within 1 second. In this paper, we present a design of the assay system and results of Monte Carlo simulations of NRF.

Journal Articles

Progress in R&D efforts on the energy recovery linac in Japan

Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06

Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.

Journal Articles

Proposal of nondestructive radionuclide assay using a high-flux $$gamma$$-ray source and nuclear resonance fluorescence

Hajima, Ryoichi; Hayakawa, Takehito; Kikuzawa, Nobuhiro; Minehara, Eisuke

Journal of Nuclear Science and Technology, 45(5), p.441 - 451, 2008/05

 Times Cited Count:66 Percentile:1.43(Nuclear Science & Technology)

A nondestructive assay system for radioactive waste management is proposed. The system utilizes nuclear resonance fluorescence triggered by a quasi-monochromatic high-flux $$gamma$$-ray generated from Compton scattering of laser photons by relativistic electrons. We employ an energy-recovery linac as an electron source and a mode-locked fiber laser followed by a laser supercavity as a photon source. The combination of these novel technologies realizes a $$gamma$$-ray flux much higher than existing sources using electron storage rings. The proposed $$gamma$$-ray source produces a quasi-monochromatic $$gamma$$ ray with a flux of $$10^{10}$$/s/keV, which is high enough for industrial applications such as nondestructive analysis of radionuclides in nuclear waste and interrogation of fissile material in cargoes. The nuclear resonance fluorescence triggered by quasi-monochromatic $$gamma$$-rays provides a versatile method of nondestructive analysis of both radioactive and stable nuclides.

Journal Articles

Demonstration of isotope imaging method by nuclear resonance fluorescence

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Toyokawa, Hiroyuki*; Ogaki, Hideaki*; Minehara, Eisuke

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.598 - 600, 2008/00

Laser-Compton-backscattered photons from an energy-recovery linac (ERL) and a high power laser realize a high-efficiency, high-flux and tunable monochromatic $$gamma$$-ray source. A nondestructive assay method by using the monoenegetic $$gamma$$-rays and nuclear resonance fluorescence (NRF) make possible to isotope imaging. The purpose of our work is to demonstrate of the NRF-based isotope imaging system. For this evaluation, we are developing a GEANT4-based Monte Carlo simulation code. In the simulation, we assume metal cubes (4$$times$$4$$times$$4 mm) of U238 and lead are contained in a concrete block of 5 cm thickness. The simulation results indicate that the nondestructive $$gamma$$ spectrometric method can be applicable in the isotope imaging.

Journal Articles

Measurement of infrared FEL pulse by FROG

Iijima, Hokuto; Nagai, Ryoji; Nishimori, Nobuyuki; Hajima, Ryoichi; Minehara, Eisuke

Dai-13-Kai FEL To High-Power Radiation Kenkyukai Proceedings, p.5 - 6, 2007/03

no abstracts in English

Journal Articles

An Interrogation method for radioactive waste by using an ERL-based high-flux $$gamma$$-ray source

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Hayakawa, Takehito; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.577 - 579, 2007/00

Laser-Compton-backscattered photons from an energy-recovery linac (ERL) and a high power laser realize a high-efficiency, high-flux and tunable monochromatic $$gamma$$-ray source. A non-destructive interrogation method by using nuclear resonance fluorescence (NRF) make possible to measure the discrimination of clearance levels of a concrete solidification radioactive waste. The purpose of our work is to design and evaluation of the NRF-based detection system. For this evaluation, we are developing a GEANT4-based Monte Carlo simulation code. Some simulations have been performed with simple models of a concrete solidification radioactive waste cask and detectors. We present a recent result of the simulation.

Journal Articles

Emittance compensation solenoid of a DC photo-cathode electron gun

Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Iijima, Hokuto; Sawamura, Masaru; Kikuzawa, Nobuhiro; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.673 - 675, 2007/00

An emittance compensation solenoid magnet is designed for a DC photo-cathode electron gun. The DC gun is now in fabrication at JAEA for an energy-recovery linac (ERL) light-source. The ERL light-source requires very low emittance electron beam to generate coherent X-rays. In order to produce the very low emittance electron beam from the DC gun, a focusing lens is indispensable to compensate the linear emittance growth. A solenoid magnet is employed for the emittance compensation lens. The solenoid magnet consists of a main coil, pure iron yoke, and a backing coil. The compensated emittance is estimated less than 0.6 mm-mrad in the bunch charge of 77 pC by PARMELA simulation.

Journal Articles

High-voltage stability requirement of a DC electron gun for an ERL light-source

Nagai, Ryoji; Hajima, Ryoichi; Iijima, Hokuto; Nishimori, Nobuyuki; Sawamura, Masaru; Kikuzawa, Nobuhiro; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.676 - 678, 2007/00

A DC electron gun is employed for an electron source of an energy-recovery linac (ERL). The electron beam parameters are fluctuated due to the instability of a high-voltage power supply of the gun. The fluctuations of the electron beam parameters are estimated for the ERL light-source. In the result of the estimation, the bunch length of the electron beam is mainly fluctuated by the instability of the high-voltage power supply. For the bunch length fluctuation of 1% or less, the required high-voltage stability is less than 1$$times$$10$$^{-4}$$. The main part of the instability of the high-voltage is the ripple of the Cockcroft-Walton circuit. The compensation of the ripple utilizing an LC filter is proposed, and the required stability is easily achieved in the preliminary design of the power supply.

Journal Articles

Estimation of HOM-BBU threshold current for an energy recovery linac

Nagai, Ryoji; Hajima, Ryoichi; Sawamura, Masaru; Nishimori, Nobuyuki; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.637 - 639, 2007/00

A collaborative project towards an ERL light source has been launched in Japan. In this project, the superconducting cavity is optimized for a high-average current beam. The latest design is a 9-cell cavity of 1.3 GHz with enlarged beam pipes and on-axis HOM absorbers. In this paper, beam breakup instabilities for the newly designed cavity is investigated. Threshold current of beam breakup at a 5-GeV ERL and possible extention to multi-turn configuration is presented.

Journal Articles

Status of ERL development at JAEA, 2007

Nagai, Ryoji; Hajima, Ryoichi; Sawamura, Masaru; Nishimori, Nobuyuki; Kikuzawa, Nobuhiro; Iijima, Hokuto; Minehara, Eisuke

Proceedings of 4th Annual Meeting of Particle Accelerator Society of Japan and 32nd Linear Accelerator Meeting in Japan (CD-ROM), p.16 - 18, 2007/00

We are proposing energy-recovery linac (ERL) based photon sources, which are a next generation X-ray light-source, a $$gamma$$-ray source for a radioactive waste management, and an EUV-FEL for a next generation lithography. Related R&D is in progress. In this paper, we summarize these proposed ERL photon sources and research activities.

Journal Articles

Quantum beam applications in nuclear energy industries

Minehara, Eisuke; Morishita, Yoshitsugu; Mizuki, Junichiro

Enerugi Rebyu, 26(8), p.15 - 18, 2006/08

The advanced quantum beam technologies (synchrotron orbital radiation and laser) are applied to the nuclear energy industrial one and many other fields, and solving various actual difficulties and acquiring much new knowledge in Quantum Beam Science Directorate, Japanese Atomic Energy Agency. Here, we would like to introduce and to explain three ones from such activities stated just above. In the text, we would like to explain in details (1) the high power laser cutting with narrow-gap in decommissioning the nuclear power reactor plants, (2) complete removing of RI (radio-isotope) contaminated surface components using non-thermal laser ablation, and (3) the discovery of the high temperature superconductor working mechanism using synchrotron-orbital-radiation beam as three typical examples.

Journal Articles

FEL oscillation with a high extraction efficiency at JAEA ERL FEL

Nishimori, Nobuyuki; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nagai, Ryoji; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.265 - 272, 2006/08

One of challenges that high power FEL oscillators with energy recovery linac (ERL) are facing is to increase the extraction FEL efficiency as high as possible. The high efficiency oscillation relaxes the total beam current needed for high power lasing and makes the FEL optical pulse length shorter, which is useful for various applications. A triple bend achromat loop with energy acceptance of 7 % has been used in an ERL FEL at JAEA. Recently we have achieved the efficiency exceeding 2 %, which accompanies large energy spread beyond the energy acceptance of the loop, by doubling the electron bunch repetition rate. The optical pulse can now interact with a fresh electron bunch every round trip, while it overlapped with an injected electron every two round trips before the doubling of the bunch repetition. This talk will summarize our recent development of a high power FEL with a high extraction efficiency at JAEA ERL FEL.

Journal Articles

Beam current doubling of JAEA ERL-FEL

Nagai, Ryoji; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nishimori, Nobuyuki; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.312 - 315, 2006/08

An energy-recovery linac (ERL) for a high-power free-electron laser (FEL) R&D program is in progress at Japan Atomic Energy Agency (JAEA). The first energy-recovery operation and FEL lasing was demonstrated in 2002 by remodeling the original superconducting linac. In the first demonstration, the accelerated beam current was same as the original linac. One of the benefits of the ERL is that the accelerating beam current can be easily increase by changing micro-pulse repetition rate without increasing the main linac RF source. After the first demonstration, the e-gun, the injector RF source, the low-level RF controller, and the operation system were improved for the beam current doubling. The doubled beam acceleration and FEL lasing have been successfully achieved with 10mA of beam current and 0.7kW of FEL power.

Journal Articles

Performance of a conventional analog $$Phi$$-A type low-level RF controller

Nagai, Ryoji; Hajima, Ryoichi; Iijima, Hokuto; Kikuzawa, Nobuhiro; Minehara, Eisuke; Nishimori, Nobuyuki; Nishitani, Tomohiro; Sawamura, Masaru

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.316 - 318, 2006/08

For an FEL application and an ERL light source, high-stability of accelerator RF amplitude and phase is required. A low-level RF controller (LLC) of the JAEA-ERL has been improved to ensure high-stability accelerating RF field. The LLC performance is tested for a 499.8MHz superconducting cavity and a 1300MHz copper cavity. The phase and amplitude stabilities of the 499.8MHz superconducting cavity within a 1ms macro-pulse are 0.0055deg-rms and 7.64$$times$$10$$^{-5}$$, respectively. For the 1300MHz copper cavity, pulse mode and CW mode were tested. In the case of pulse mode, the phase and amplitude stabilities are 0.011deg-rms and 7.64$$times$$10$$^{-5}$$, respectively. In the case of CW mode, the phase and amplitude stabilities are 0.011deg-rms and 6.68$$times$$10$$^{-5}$$, respectively.

Journal Articles

Development of frequency-resolved optical gating for measurement of correlation between time and frequency of chirped FEL

Iijima, Hokuto; Hajima, Ryoichi; Minehara, Eisuke; Nagai, Ryoji; Nishimori, Nobuyuki

Proceedings of 28th International Free Electron Laser Conference (FEL 2006) (CD-ROM), p.308 - 311, 2006/08

A femtosecond infrared-chirped FEL is an effective way of dissociating molecules without the intramolecular vibrational redistribution. At Japan Atomic Energy Agency (JAEA), an energy recovery linac (ERL) has been investigated to provide a high power FEL at far-infrared region. Normally the long-pulse electron beam is operated by the ERL; therefore the high-power chirped pulse can be generated. Until now, the distribution of frequency in the FEL pulse was measured to be $$Deltaomega / omega_{0}$$= 14% with the wavelength of 23 $$mu$$m and the pulse width of 320 fs at FWHM via FR-SHG autocorrelator. However the variation of frequency during the pulse was not measured. In order to measure the correlation between time and frequency in the chirped pulse directly, we have started to construct an FEL transport system and the frequency-resolved optical gating. Now we are measuring basic parameters of the chirped pulse (beam size, power and so on) in the experimental room.

228 (Records 1-20 displayed on this page)