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Journal Articles

Enhanced $$d$$-$$p$$ hybridization intertwined with anomalous ground state formation in the van der Waals itinerant magnet Fe$$_5$$GeTe$$_2$$

Yamagami, Kohei*; Fujisawa, Yuita*; Pardo-Almanza, M*; Smith, B. R. M.*; Sumida, Kazuki; Takeda, Yukiharu; Okada, Yoshinori*

Physical Review B, 106(4), p.045137_1 - 045137_8, 2022/07

 Times Cited Count:2 Percentile:37.1(Materials Science, Multidisciplinary)

Journal Articles

Anionic fluoro complex of element 105, Db

Kasamatsu, Yoshitaka*; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Li, Z.; Ishii, Yasuo; Tome, Hayato*; Sato, Tetsuya; Kikuchi, Takahiro; Nishinaka, Ichiro; et al.

Chemistry Letters, 38(11), p.1084 - 1085, 2009/10

 Times Cited Count:14 Percentile:49.01(Chemistry, Multidisciplinary)

We report on the characteristic anion-exchange behavior of the superheavy element dubnium (Db) with atomic number Z = 105 in HF/HNO$$_{3}$$ solution at the fluoride ion concentration [F$$^{-}$$] = 0.003 M. The result clearly demonstrates that the fluoro complex formation of Db is significantly different from that of the group-5 homologue Ta in the 6th period of the periodic table while the behavior of Db is similar to that of the lighter homologue Nb in the 5th period.

Journal Articles

Experimental progress on zonal flow physics in toroidal plasmas

Fujisawa, Akihide*; Ido, Takeshi*; Shimizu, Akihiro*; Okamura, Shoichi*; Matsuoka, Keisuke*; Iguchi, Harukazu*; Hamada, Yasuji*; Nakano, Haruhisa*; Oshima, Shinsuke*; Ito, Kimitaka*; et al.

Nuclear Fusion, 47(10), p.S718 - S726, 2007/10

 Times Cited Count:100 Percentile:95.33(Physics, Fluids & Plasmas)

Present status of experiments on zonal flows is overviewed. Innovative use of modern diagnostics has revealed the existence of zonal flows, their spatio-temporal characteristics, their relationship with turbulence, and their effects on confinement. Particularly a number of observations have been accumulated on the oscillatory branch of the zonal flow, dubbed as geodesic acoustic modes suggesting necessity of theories to give their proper description. Several new methods have elucidated the zonal flow generation processes from the turbulence. Further investigation of relationship between the zonal flows and confinement is strongly encouraged as cross-device activity.

Journal Articles

Experimental progress on zonal flow physics in toroidal plasmas

Fujisawa, Akihide*; Ido, Takeshi*; Shimizu, Akihiro*; Okamura, Shoichi*; Matsuoka, Keisuke*; Hamada, Yasuji*; Hoshino, Katsumichi; Nagashima, Yoshihiko*; Shinohara, Koji; Nakano, Haruhisa*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03

Present status of experiments on zonal flows is overviewed. Innovative use of traditional and modern diagnostics has revealed unambiguously the existense of the zonal flows, their spatio-temporal caracteristics, their relationship with turbulence, and their effects on confinement. Particularly, a number of observations have been accumulated on the oscillatory branch of zonal flows, dubbed geodesic acoustic modes, suggesting necessity of theories to give their proper description. Furthur investigation of relationship between zonal flows and confinement is strongly encouraged as cross-device activity.

Journal Articles

Soft X-ray beamline for spectroscopy of solids at SPring-8

Saito, Yuji; Kimura, Hiroaki*; Suzuki, Yoshio*; Nakatani, Takeshi*; Matsushita, Tomohiro*; Muro, Takayuki*; Miyahara, Tsuneaki*; Fujisawa, M.*; Soda, Kazuo*; Ueda, Shigenori*; et al.

Nuclear Instruments and Methods in Physics Research A, 467-468(Part.1), p.553 - 556, 2001/07

 Times Cited Count:23 Percentile:82.47(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Characterization of disruption phenomenology in ITER

Yoshino, Ryuji; D.J.Campbell*; E.Fredrickson*; Fujisawa, Noboru; N.Granetz*; Gruber, O.*; T.C.Hender*; D.A.Humphreys*; N.Ivanov*; S.Jardin*; et al.

Fusion Energy 2000 (CD-ROM), 4 Pages, 2001/05

no abstracts in English

JAEA Reports

Research about the long-term stability of TRU waste disposal system

Tanaka, M.*; Fujisawa, O.*; Okutsu, Kazuo*; Takamura, Hisashi*; Aoyagi, Takayoshi*

JNC TJ8400 2001-031, 70 Pages, 2001/02

JNC-TJ8400-2001-031.pdf:6.27MB

no abstracts in English

JAEA Reports

Research about the long-term stability of TRU waste disposal system

Tanaka, M.*; Fujisawa, O.*; Okutsu, Kazuo*; Takamura, Hisashi*; Aoyagi, Takayoshi*

JNC TJ8400 2001-030, 82 Pages, 2001/02

JNC-TJ8400-2001-030.pdf:13.47MB

This research arranged the relation with the events (the events which happen to each part grade of disposal institution and change) produced to the characteristic in connection with low permeability and the disposal system of barrier material, such as permeability. The important events which can affect the long stability of the performance which barrier material has by that cause, and its relation were extracted. And, the physical-properties data acquisition of bentonite supposing the events considered to be generated to a disposal system in the future was carried out. The research result of this year is shown below. (1)About the events considered to affect permeability, "the present knowledge and the reseach result" and the "view of a design about a event" were arranged. And it divided and arranged the time of construction and operation, and after closure. Consequently, the subject required in order to check the long stability of TRU waste disposal system was able to be extracted. (2)In order for the research in the last year to estimate the self-seal nature of a bentonite, swelling pressure and the permeability at the time of the bentonite which generated the maximum swelling pressure under the restricted condition for Na-bentonite and Ca-bentonite 100% material re-swelling to the space produced after that were acquired. About this result, the view of effective bentonite dryness density was applied, and the self-seal performance of the assumed material (bentonite 70%, silica 30%) examined in TRU waste disposal concept examination document was evaluated. In order to check the validity of the evaluation in the last year, the self-seal performance check experiment was conducted about the silica mixture bentonite. Consequently, the soundness of a barrier system was able to be checked by the specification of H12 TRU report.

Journal Articles

Performance of a very high resolution soft X-ray beamline BL25SU with a twin-helical undulator at SPring-8

Saito, Yuji; Kimura, Hiroaki*; Suzuki, Yoshio*; Nakatani, Takeshi*; Matsushita, Tomohiro*; Muro, Takayuki*; Miyahara, Tsuneaki*; Fujisawa, M.*; Soda, Kazuo*; Ueda, Shigenori*; et al.

Review of Scientific Instruments, 71(9), p.3254 - 3259, 2000/09

 Times Cited Count:184 Percentile:98.98(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

A Study of disposal concept for TRU waste, 5; A Study on the mechanical properties of engineered barrier materials

Tanaka, M.*; Yamamoto, H.*; Fujisawa, O.*; Okutsu, Kazuo*; Miura, K.*; Takamura, Hisashi*

JNC TJ8400 2000-036, 196 Pages, 2000/02

JNC-TJ8400-2000-036.pdf:23.76MB

TRU waste should be isolated from biosphere for a long period of time as it includes long lived nuclides. In this study, (1) data were conected on the mechanical properties of engineered barrier materials, (2) affection on the mechanical properties of Na bentonito by salt water was studied and (3) soundness of the disposal system against changes in the volume of engineered banier was evaluated, to examine critical events related to the long-term soundness of the disposal system. Described below are the results of the studies. (1) The swelling pressure, swelling amount and permeability were obtained for a material consisting of NaCa-exchanged bentonito and silica sand with a relative weight of 30% (with a dry density of 1.6 Mgm$$^{-3}$$) by supplying saturated calcium hydroxide aqeous solution. As a result, it was confirmed that the swelling pressure and permeability were approximately estimated from the relation between these properties and the effective dry density of bentonito. (2) The swelling pressure, swelling amount and permeability were obtained for a material consisting of salty Na bentonito and silica sand with a relative weight of 30% (with a dry density of 1.6 Mgm$$^{-3}$$) by supplying artifical salt water. As a result, it was confirmed that these properties were approximately these properties of NaCa-bentonito. (3) Tests were conducted as a part of the evaluation of system soundness against changes in the volume of engineered barrier. Development of a void around bentonito was assumed. Self sealing of Na and NaCa-exchanged bentonito, and theirs water cut-off capability and swelling pressure were investigated.As a result, it was confirmed that the change of permeability and swelling pressure under self sealing of bentonito. Based on the test results (i.e. the both relations between the swelling pressure and dry density, and the permeability and dry density), soundness of the system was verified against changes of the volume of engineered barrier materials.

JAEA Reports

A Study of disposal concept for TRU waste, 5; Adtudy on the mechanical properties of engineered barrier materials

Tanaka, M.*; Yamamoto, H.*; Fujisawa, O.*; Okutsu, Kazuo*; Miura, K.*; Takamura, Hisashi*

JNC TJ8400 2000-035, 59 Pages, 2000/02

JNC-TJ8400-2000-035.pdf:8.87MB

no abstracts in English

Journal Articles

Twin helical undulator beamline for soft X-ray spectroscopy at SPring-8

Saito, Yuji; Nakatani, Takeshi*; Matsushita, T.*; Miyahara, Tsuneaki*; Fujisawa, M.*; *; *; *; *; *; et al.

Journal of Synchrotron Radiation, 5, p.542 - 544, 1998/00

 Times Cited Count:62 Percentile:94.45(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Spin-resolved core-level photoemission spectra of ferromagnetic nickel

Saito, Yuji; Suga, Shigemasa*; Kakizaki, A.*; Matsushita, T.*; Imada, S.*; Daimon, H.*; Ono, Kanta*; Fujisawa, M.*; Kinoshita, T.*; Ishii, T.*; et al.

Journal of Electron Spectroscopy and Related Phenomena, 78, p.329 - 332, 1996/05

 Times Cited Count:0 Percentile:0.03(Spectroscopy)

no abstracts in English

Oral presentation

Anion-exchange behavior of Db in HF/HNO$$_{3}$$ mixed solution using an on-line chemical apparatus

Tsukada, Kazuaki; Kasamatsu, Yoshitaka*; Asai, Masato; Toyoshima, Atsushi; Ishii, Yasuo; Li, Z.; Kikuchi, Takahiro; Sato, Tetsuya; Nagame, Yuichiro; Sch$"a$del, M.; et al.

no journal, , 

We have investigated the chemical behavior of Db together with its group-5 homologues by anion-exchange chromatography in HF/HNO$$_{3}$$ mixed solution using a rapid online chemical apparatus (AIDA-II). The nuclides $$^{262}$$Db, $$^{88}$$Nb and $$^{169,170}$$Ta were produced in the $$^{248}$$Cm($$^{19}$$F, ${it 5}$n), $$^{nat}$$Ge($$^{19}$$F, ${it x}$n) and $$^{nat}$$Gd($$^{19}$$F, ${it x}$n) reactions, respectively, at the JAEA tandem accelerator. On-line anion-exchange separations of Db, Nb and Ta were performed using the AIDA-II. Thousand times of anion-exchange separations were conducted using AIDA-II. $$alpha$$ events were registered, and the $${it K_d}$$ values for Db was evaluated. From these results, the adsorption sequence Pa $$<$$ Db $$<$$ Nb $$ll$$ Ta was determined. The present result shows a notable difference in the adsorption behavior between Db and its homologue Ta. In the conference, the present status and the perspective of the aqueous chemistry of Db at JAEA will be also presented.

Oral presentation

Progress of understanding negative triangular tokamak configuration

Kikuchi, Mitsuru; Fasoli, A.*; Takizuka, Tomonori*; Diamond, P.*; Medvedev, S.*; Duan, X.*; Zushi, Hideki*; Furukawa, Masaru*; Kishimoto, Yasuaki*; Wu, Y.*; et al.

no journal, , 

Power and particle control is challenging for standard D-shaped H-mode scenario in tokamak. Possibility of negative triangularity as innovative tokamak concept is discussed by Kikuchi et al. Experimental and numerical studies of negative triangular plasma at CRPP-EPFL success-fully demonstrated improved connement and the weakening of the SOL flow acceleration is implied for the negative triangularity. Recent studies on mechanism of type II and grassy ELM show importance of closure of second stability access to achieve small ELM regimes and also kinetic effects. Medvedev showed that closure of second stability also occurs for negative triangularity. But the MHD stability in negative triangularity is a bit more complicated so that closure of second stability does not imply easy access to small ELM regimes. We discuss critical elements behind.

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