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Journal Articles

Two-dimensional charge fluctuation in $$beta$$-Na$$_{0.33}$$V$$_{2}$$O$$_{5}$$

Owada, Kenji; Yamauchi, Toru*; Fujii, Yasuhiko*; Ueda, Yutaka*

Physical Review B, 85(13), p.134102_1 - 134102_4, 2012/04

 Times Cited Count:9 Percentile:38.45(Materials Science, Multidisciplinary)

We have investigated the critical phenomena of the metal-to-insulator (MI) transition of $$beta$$-Na$$_{0.33}$$V$$_{2}$$O$$_{5}$$. The critical exponent $$beta$$ of 0.226(3) and anisotropic diffuse scattering suggest that the MI transition of $$beta$$-Na$$_{0.33}$$V$$_{2}$$O$$_{5}$$ is two-dimensional in nature and that the dimension of the order parameter is not Ising. The non-Ising-like order parameter indicates that the MI transition is not a simple order-disorder type such as that of $$alpha$$'-NaV$$_{2}$$O$$_{5}$$ but charge-density-wave-like, where the valence at each V site is continuous and the arrangement is modulated. This closely corresponds to the situation predicted by neutron diffraction measurements and NMR measurements.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Study on improvement of reliability on inventory assessment in vitrified waste for long-term safety of geological disposal

Ishikawa, Masumi*; Kaneko, Satoru*; Kitayama, Kazumi*; Ishiguro, Katsuhiko*; Ueda, Hiroyoshi*; Wakasugi, Keiichiro*; Shinohara, Nobuo; Okumura, Keisuke; Chino, Masamichi; Moriya Noriyasu*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 8(4), p.304 - 312, 2009/12

Since quality control issues for vitrified waste are defined mainly with the focus on the transport and storage of the waste rather than the long-term safety of geological disposal, they do not cover inventories of long-lived nuclides which are of most interest in the safety assessment of geological disposal. Therefore we suggest a flow chart for assessment of inventories of long-lived nuclides in the vitrified waste focusing on measured value. We started a programme to examine the applicability as well as to improve reliability of nuclide generation/decay code and nuclear data library using liquid waste from spent fuel with clear irradiation history. To solve the issue of quality control for vitrified waste, comprehensive study is needed in aspects not only of geological disposal field but also of operation of nuclear power plant, reprocessing of spent fuel and vitrification of liquid waste. This study is a pioneering study to integrate them.

Journal Articles

Report on ITPA meetings, 24

Idomura, Yasuhiro; Yoshida, Maiko; Yagi, Masatoshi*; Tanaka, Kenji*; Hayashi, Nobuhiko; Sakamoto, Yoshiteru; Tamura, Naoki*; Oyama, Naoyuki; Urano, Hajime; Aiba, Nobuyuki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(12), p.952 - 955, 2008/12

no abstracts in English

Journal Articles

Ultra-fast pulse radiolysis; A Review of the recent system progress and its application to study on initial yields and solvation processes of solvated electrons in various kinds of alcohols

Muroya, Yusa*; Lin, M.; Han, Z.*; Kumagai, Yuta; Sakumi, Akira*; Ueda, Toru*; Katsumura, Yosuke

Radiation Physics and Chemistry, 77(10-12), p.1176 - 1182, 2008/10

 Times Cited Count:17 Percentile:74.66(Chemistry, Physical)

In order to study radiation-induced fast phenomena, a new pulse radiolysis system with higher time resolution based on pulse-and-probe method was developed and utilized for practical work. A few picosecond electron beam generated from a linear accelerator, in which a laser photocathode RF-gun is introduced, was synchronized with a femtosecond laser pulse which is employed as the analyzing light. The synchronization precision between them was suppressed within 1.6 ps (rms). Converting the fundamental laser into white light continuum or optical parametric amplification allows to measure in the wide wavelength from visible to infrared region.

Journal Articles

Research and development of nuclear fusion

Ushigusa, Kenkichi; Seki, Masahiro; Ninomiya, Hiromasa; Norimatsu, Takayoshi*; Kamada, Yutaka; Mori, Masahiro; Okuno, Kiyoshi; Shibanuma, Kiyoshi; Inoue, Takashi; Sakamoto, Keishi; et al.

Genshiryoku Handobukku, p.906 - 1029, 2007/11

no abstracts in English

Journal Articles

Physics issues and simulation of the JT-60 SA divertor for large heat and particle handling

Asakura, Nobuyuki; Kawashima, Hisato; Shimizu, Katsuhiro; Sakurai, Shinji; Fujita, Takaaki; Takenaga, Hidenobu; Nakano, Tomohide; Kubo, Hirotaka; Higashijima, Satoru; Hayashi, Takao; et al.

Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00

Divertor design for the JT-60 SA has been progressing in order to handle large heat flux during full pulse duration of 100 s. Divertor should be suitable for single null plasma experiments with the full power injection of 41 MW. The simulation results using 2D fluid (plasma) and Monte-Carlo (neutral) code are summarized. Lower single-null divertor is designed for ITER-like plasma configuration in order to study physics concept of the ITER divertor: control of the plasma detachment. Simulation results for various divertor geometries showed that the vertical target with V-shaped corner can produce plasma detachment near the outer strike-point for medium edge plasma density. It was also demonstrated that the divertor plasma became attached to move the outer strike point above the V-corner, suggesting that recover from sever detachment can be achieved by changing the plasma location. USN divertor will be designed for high-$$beta$$ plasma experiments with the highest shaping plasma of S=6.

Journal Articles

Measurement of emittance for electron bunches compressed by velocity bunching via double-slit-scan method

Iijima, Hokuto; Hajima, Ryoichi; Uesaka, Mitsuru*; Sakumi, Akira*; Sakamoto, Fumito*; Ueda, Toru*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.501 - 503, 2005/07

We report the availability of velocity bunching in an energy recovery linac (ERL) by a numerical analysis, and the plan of precise measurement of bunching emittance via a double-slit-scan method. The simulation performed for eight TESLA-type cavities reveals successful bunch compression from 3.2 ps to 0.17 ps. Since the residual energy spread after velocity bunching is considerably smaller than the correlated energy spread required for magnetic compression through a recirculation loop, velocity bunching is useful to realized short-pulse and high-brightness X-rays by ERL. The emittance of velocity bunching was calculated to be 1.5 $$pi$$mm.mrad for the bunch charge of 77pC without the emittance compensation by an external solenoid field. Although the emittance growth due to the space-charge effect was small in the simulation, it is necessary to evaluate the emittance-growth mechanism under velocity bunching. Therefore, the emittance measurement via double-slit-scan method is carrying out in the UTNL-18L.

Journal Articles

Experimental verification of velocity bunching via shot-by-shot measurement at S-band photoinjector and linac

Iijima, Hokuto; Uesaka, Mitsuru*; Sakamoto, Fumito*; Ueda, Toru*; Kumagai, Noritaka*; Serafini, L.*

Japanese Journal of Applied Physics, Part 1, 44(7A), p.5249 - 5253, 2005/01

 Times Cited Count:8 Percentile:32.22(Physics, Applied)

We represent an experimental verification of a bunch compression method named "velocity bunching". The velocity bunching based on the rectilinear compression uses a traveling wave accelerating tube as a compressor. The experiment was performed by an S-band photoinjector and a linac at Nuclear Engineering Research Laboratory, University of Tokyo. The shot-by-shot bunch length was measured to be 0.5 $$pm$$ 0.1 ps (rms) in average by the femtosecond streak camera for a bunch charge of 1 nC. The experimental result is in good agreement with PARMELA simulations.

Journal Articles

Instability of synchronization between laser and beam depending on environmental noise at photocathode RF gun

Uesaka, Mitsuru*; Iijima, Hokuto; Ueda, Toru*; Muroya, Yusa*; Sakumi, Akira*; Kumagai, Noritaka*; Tomizawa, Hiromitsu*

Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.628 - 630, 2004/08

no abstracts in English

Journal Articles

Phase relationships and equations of state for FeS at high pressures and temperatures and implications for the internal structure of Mars

Urakawa, Satoru*; Someya, Keiko*; Terasaki, Hidenori*; Katsura, Tomoo*; Yokoshi, Sho*; Funakoshi, Kenichi*; Utsumi, Wataru; Katayama, Yoshinori; Sueda, Yuichiro*; Irifune, Tetsuo*

Physics of the Earth and Planetary Interiors, 143-144, p.469 - 479, 2004/06

 Times Cited Count:61 Percentile:72.92(Geochemistry & Geophysics)

no abstracts in English

Journal Articles

Progress in physics and technology developments for the modification of JT-60

Tamai, Hiroshi; Matsukawa, Makoto; Kurita, Genichi; Hayashi, Nobuhiko; Urata, Kazuhiro*; Miura, Yushi; Kizu, Kaname; Tsuchiya, Katsuhiko; Morioka, Atsuhiko; Kudo, Yusuke; et al.

Plasma Science and Technology, 6(1), p.2141 - 2150, 2004/02

 Times Cited Count:2 Percentile:6.52(Physics, Fluids & Plasmas)

The dominant issue for the the modification program of JT-60 (JT-60SC) is to demonstrate the steady state reactor relevant plasma operation. Physics design on plasma parameters, operation scenarios, and the plasma control method are investigated for the achievement of high-$$beta$$. Engineering design and the R&D on the superconducting magnet coils, radiation shield, and vacuum vessel are performed. Recent progress in such physics and technology developments is presented.

Journal Articles

Objectives and design of the JT-60 superconducting tokamak

Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Chujo, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.

Nuclear Fusion, 43(7), p.606 - 613, 2003/07

no abstracts in English

Journal Articles

Objectives and design of the JT-60 superconducting tokamak

Ishida, Shinichi; Abe, Katsunori*; Ando, Akira*; Cho, T.*; Fujii, Tsuneyuki; Fujita, Takaaki; Goto, Seiichi*; Hanada, Kazuaki*; Hatayama, Akiyoshi*; Hino, Tomoaki*; et al.

Nuclear Fusion, 43(7), p.606 - 613, 2003/07

 Times Cited Count:33 Percentile:69.18(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Effect of a laser prepulse on a narrow-cone ejection of MeV electrons from a gas jet irradiated by an ultrashort laser pulse

Hosokai, Tomonao*; Kinoshita, Kenichi*; Zhidkov, A.*; Nakamura, Kei*; Watanabe, Takahiro*; Ueda, Toru*; Kotaki, Hideyuki; Kando, Masaki; Nakajima, Kazuhisa; Uesaka, Mitsuru*

Physical Review E, 67(3), p.036407_1 - 036407_8, 2003/03

 Times Cited Count:81 Percentile:93.13(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

MK-III Modification work of heat transport system in JOYO; Dismantling and sodium cleaning of secondary cooling system components

Ishii, Takayuki; Isozaki, Kazunori; Ashida, Takashi; Minakawa, Satoru; Terakado, Tsuguo; Nogami, Hiroshi*; Kakurai, Katsuhiko*; Ueda, Soji*; Kawahara, Hirotaka; Ichige, Satoshi; et al.

JNC TN9410 2002-013, 86 Pages, 2002/11

JNC-TN9410-2002-013.pdf:68.29MB

The MK-III project has been proceeding to improve the irradiation capability of the experimental fast reactor JOY0. The MK-III project has three major purposes such as increase high neutron flux, improvement of plant availability factor and upgrading in irradiation techniques. Thermal output by core transformation for high neutron flux was increased from 100MWt to 140MWt. The main components in the cooling system such as IHX(Intermediate Heat Exchanger) and DHX(Dump Heat Exchanger) were replaced in MK-III modification in order to increase heat removal capability. Heat transfer capacity of IHX was increased from 50MWt/Unit to 70MWt/Unit and that of DHX was increased from 25MWt/Unit to 35MWt/Unit. These components replacement has been safety completed from october 30, 2000 through September 21, 2001. This report summarizes the way, results and safety measures about dismantling of no sodium adhered components and such as DHX blower and sodium cleaning of sodium components such as the DHX, the pipes connected with DHX and secondary side of IHX. Dismantling and sodium cleaning of secondary cooling system components were performed safely and efficiently as almost planned. The total amount of removed sodium was about 13.5kg.

Journal Articles

Compact X-ray sources by intense laser interactions with beams and plasmas

Kotaki, Hideyuki; Kando, Masaki; Dewa, Hidenori; Kondo, Shuji; Watanabe, Takahiro*; Ueda, Toru*; Kinoshita, Kenichi*; Yoshii, Koji*; Uesaka, Mitsuru*; Nakajima, Kazuhisa

Nuclear Instruments and Methods in Physics Research A, 455(1), p.166 - 171, 2000/11

 Times Cited Count:14 Percentile:66.62(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Generation and application of femtosecond X-ray pulse

Uesaka, Mitsuru*; Kotaki, Hideyuki; Nakajima, Kazuhisa; Harano, Hideki*; Kinoshita, Kenichi*; Watanabe, Takahiro*; Ueda, Toru*; Yoshii, Koji*; Kando, Masaki; Dewa, Hidenori; et al.

Nuclear Instruments and Methods in Physics Research A, 455(1), p.90 - 98, 2000/11

 Times Cited Count:36 Percentile:88.99(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Experimental verification of laser photocathode RF gun as an injector for a laser plasma accelerator

Uesaka, Mitsuru*; Kinoshita, Kenichi*; Watanabe, Takahiro*; Sugahara, Jun*; Ueda, Toru*; Yoshii, Koji*; Kobayashi, Tetsuya*; Halz, N.*; Nakajima, Kazuhisa; Sakai, Fumio*; et al.

IEEE Transactions on Plasma Science, 28(4), p.1133 - 1142, 2000/08

 Times Cited Count:14 Percentile:41.88(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Generation, diagnosis and application of femtosecond electron single bunch

Uesaka, Mitsuru*; Watanabe, Takahiro*; Kinoshita, Kenichi*; Sugahara, Jun*; Harano, Hideki*; Ueda, Toru*; Yoshii, Koji*; Nakajima, Kazuhisa; Sakai, Fumio*; Kotaki, Hideyuki; et al.

Nihon Genshiryoku Gakkai-Shi, 42(4), p.310 - 324, 2000/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

46 (Records 1-20 displayed on this page)