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Journal Articles

Anisotropic spin fluctuations in the heavy fermion systems; Case studies of CePd$$_5$$Al$$_2$$ and NpPd$$_5$$Al$$_2$$

Sakai, Hironori; Chudo, Hiroyuki; Tokunaga, Yo; Kambe, Shinsaku; Haga, Yoshinori; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*; Homma, Yoshiya*; Aoki, Dai*; et al.

Journal of the Physical Society of Japan, 81(Suppl.B), p.SB003_1 - SB003_6, 2012/12

 Times Cited Count:7 Percentile:46.8(Physics, Multidisciplinary)

In the so-called 115 family members with chemical formulae of Ce$$T$$In$$_5$$ ($$T$$=Co, Rh, Ir) and $$An$$$$T$$Ga$$_5$$ ($$An$$=U, Np, Pu), our analysis of the Knight shift and spin-lattice relaxation rates suggests that larger XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states would favor $$d$$-wave superconductivity with higher $$T_c$$. In order to examine this working hypothesis, the anisotropy ratios of antiferromagnetic fluctuations are derived from our NMR results for the superconductor NpPd$$_5$$Al$$_2$$ and antiferromagnet CePd$$_5$$Al$$_2$$, which are tetragonal compounds with a 115-related structure. CePd$$_5$$Al$$_2$$ shows Ising-type anisotropy, which is the same anisotropy as in the ordered state. On the other hand, NpPd$$_5$$Al$$_2$$ shows XY-type anisotropy just above $$T_c$$.

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Study of plasma current decay in the initial phase of high poloidal beta disruptions in JT-60U

Shibata, Yoshihide*; Watanabe, Kiyomasa*; Ono, Noriyasu*; Okamoto, Masaaki*; Isayama, Akihiko; Kurihara, Kenichi; Oyama, Naoyuki; Nakano, Tomohide; Kawano, Yasunori; Matsunaga, Go; et al.

Plasma and Fusion Research (Internet), 6, p.1302136_1 - 1302136_4, 2011/10

no abstracts in English

Journal Articles

Report on ITPA meeting, 33

Asakura, Nobuyuki; Ashikawa, Naoko*; Ueda, Yoshio*; Ono, Noriyasu*; Tanabe, Tetsuo*; Nakano, Tomohide; Masuzaki, Suguru*; Itami, Kiyoshi; Kawano, Yasunori; Kawahata, Kazuo*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 87(7), p.485 - 486, 2011/07

no abstracts in English

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 31

Suzuki, Takahiro; Isayama, Akihiko; Yoshida, Maiko; Aiba, Nobuyuki; Shinohara, Koji; Nakano, Tomohide; Kawano, Yasunori

Purazuma, Kaku Yugo Gakkai-Shi, 86(12), p.717 - 721, 2010/12

no abstracts in English

Journal Articles

$$^{105}$$Pd NQR study on NpPd$$_5$$Al$$_2$$ and CePd$$_5$$Al$$_2$$

Chudo, Hiroyuki; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Aoki, Dai*; Haga, Yoshinori; Matsuda, Tatsuma; Homma, Yoshiya*; Nakano, Yasunori*; Honda, Fuminori*; et al.

Journal of Physics; Conference Series, 200, p.012020_1 - 012020_4, 2010/02

 Times Cited Count:3 Percentile:74.38

We report the results of $$^{105}$$Pd NQR experiments on NpPd$$_5$$Al$$_2$$ and CePd$$_5$$Al$$_2$$. In the normal state at 6 K, the $$^{105}$$Pd NQR spectrum consists of four lines in both systems. These lines can be assigned to two sets of $$pm1/2leftrightarrowpm3/2$$ and $$pm3/2leftrightarrowpm5/2$$ NQR transitions arising from two crystallographically in equivalent Pd sites. From the analysis of the $$^{105}$$Pd NQR spectrum the nuclear quadrupole frequency $$nu_Q$$, asymmetry parameter $$eta$$ and electric field gradient $$V_{zz}$$ have been deduced.

Journal Articles

Magnetic and Fermi surface properties of CePd$$_5$$Al$$_2$$ and PrPd$$_5$$Al$$_2$$

Nakano, Yasunori*; Honda, Fuminori*; Takeuchi, Tetsuya*; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; Kindo, Koichi*; Yamamoto, Etsuji; Haga, Yoshinori; Settai, Rikio*; Yamagami, Hiroshi*; et al.

Journal of the Physical Society of Japan, 79(2), p.024702_1 - 024702_9, 2010/02

 Times Cited Count:15 Percentile:67.62(Physics, Multidisciplinary)

Journal Articles

Study of current decay time during disruption in JT-60U tokamak

Shibata, Yoshihide*; Watanabe, Kiyomasa*; Okamoto, Masaaki*; Ono, Noriyasu*; Isayama, Akihiko; Kurihara, Kenichi; Nakano, Tomohide; Oyama, Naoyuki; Kawano, Yasunori; Matsunaga, Go; et al.

Nuclear Fusion, 50(2), p.025015_1 - 025015_7, 2010/01

 Times Cited Count:14 Percentile:52.54(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Report on ITPA meetings, 26

Nakano, Tomohide; Yoshida, Maiko; Suzuki, Takahiro; Oyama, Naoyuki; Kawano, Yasunori; Isayama, Akihiko; Hamamatsu, Kiyotaka; Asakura, Nobuyuki

Purazuma, Kaku Yugo Gakkai-Shi, 85(7), p.472 - 475, 2009/07

no abstracts in English

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meetings, 21

Kawahata, Kazuo*; Kawano, Yasunori; Kusama, Yoshinori; Mase, Atsushi*; Sasao, Mamiko*; Ide, Shunsuke; Oikawa, Toshihiro; Suzuki, Takahiro; Takase, Yuichi*; Nakamura, Yukio*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(5), p.297 - 298, 2008/05

no abstracts in English

Journal Articles

Investigation on extraction methods of environmental iodine

Kubota, Takumi*; Nakano, Tomoko*; Amano, Hikaru; Suzuki, Takashi; Mahara, Yasunori*

JAEA-Conf 2008-003, p.36 - 39, 2008/04

In analysis of environmental iodine, samples containing low I-129 and low iodine amount are subject to contamination from reagents and apparatus. We measured the isotopic ratio of I-129/I-127 in brine that was collected at Mobara in Chiba prefecture and was characterized as having a high iodine concentration and a low isotopic ratio. The results, however, showed high isotopic ratios. We suspected that the contamination was caused by using halogen containing reagents because the samples treated with Cl-form anion exchange resin in iodine extraction process were strongly contaminated. In this study, we have conducted halogen-free extraction processes such as ion exchange and solvent extraction whose recovery has been investigated with $$gamma$$ spectrometry of I-126 produced through photonuclear reaction with the KURRI LINAC. The total iodine recovery through ion exchange with NO$$_{3}$$-form anion exchange resin and solvent extraction with dodecane was more than 80%.

Journal Articles

Pressure-induced superconductivity in antiferromagnet CePd$$_5$$Al$$_2$$

Honda, Fuminori*; M$'e$asson, M.-A.*; Nakano, Yasunori*; Yoshitani, Naohisa*; Yamamoto, Etsuji; Haga, Yoshinori; Takeuchi, Tetsuya*; Yamagami, Hiroshi*; Shimizu, Katsuya*; Settai, Rikio*; et al.

Journal of the Physical Society of Japan, 77(4), p.043701_1 - 043701_4, 2008/04

 Times Cited Count:37 Percentile:81.74(Physics, Multidisciplinary)

Journal Articles

Report of meetings of ITPA (International Tokamak Physics Activity), 19

Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09

This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 18

Kawahata, Kazuo*; Kawano, Yasunori; Kusama, Yoshinori; Mase, Atsushi*; Sasao, Mamiko*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(2), p.195 - 198, 2007/02

no abstracts in English

Journal Articles

Evaluation of dependence of current decay time on electron temperature measured by He I line intensity ratios in JT-60U tokamak

Okamoto, Masaaki*; Hiraishi, Takehiro*; Ono, Noriyasu*; Takamura, Shuichi*; Nakano, Tomohide; Kawano, Yasunori; Ozeki, Takahisa; Sugihara, Masayoshi

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

It is of importance to evaluate the decay time of the plasma current for estimation of the electromagnetic force acting on the vacuum vessel during plasma disruptions in tokamak devices. The L/R model predicts that the decay time is proportional to three-haves power of the electron temperature, indicating the importance of the electron temperature for the estimation. However, it is difficult to measure the electron temperature of the disruptive plasma with the Langmuir probe due to the heat flux and due to the significant electromagnetic force. We propose a measurement technique of the electron temperature by using temperature-sensitive He I lines with high time resolution. In this method, the incident light to a spectrometer is divided into three, each of which transmits a bandpass filter, and then is measured with an absolutely calibrated photo-multiplier. The measured intensity ratios are analyzed with a collisional-radiative model. It is confirmed that the electron temperature determined by this technique is in agreement with that measured by a Langmuir probe in some devices. In the present work, the temporal evolution of the electron temperature during the disruptive plasma of JT-60U is measured with this technique.

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meetings, 17

Asakura, Nobuyuki; Kato, Takako*; Nakano, Tomohide; Takamura, Shuichi*; Tanabe, Tetsuo*; Iio, Shunji*; Nakajima, Noriyoshi*; Ono, Yasushi*; Ozeki, Takahisa; Takechi, Manabu; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 82(7), p.448 - 450, 2006/07

no abstracts in English

Journal Articles

Electron density behavior during fast termination phase of post-disruption runaway plasma

Kawano, Yasunori; Nakano, Tomohide; Asakura, Nobuyuki; Tamai, Hiroshi; Isayama, Akihiko; Kondoh, Takashi; Hatae, Takaki; Takenaga, Hidenobu; Ide, Shunsuke

Purazuma, Kaku Yugo Gakkai-Shi, 81(10), p.743 - 744, 2005/10

Electron density of post-disruption runaway plasmas in JT-60U has been measured by the tangential CO$$_{2}$$ laser interferometer. Increases in electron density after the first drop of runaway plasma current have been observed during a fast termination phase of the runaway plasma. At the second current drop, an increase in electron density with multiple spikes or oscillation with the period of 1 ms has been found. It is suggested that the increased electron density seems to take part in the shorter current decay time after the second current drop.

Journal Articles

Characteristics of post-disruption runaway electrons with impurity pellet injection

Kawano, Yasunori; Nakano, Tomohide; Isayama, Akihiko; Asakura, Nobuyuki; Tamai, Hiroshi; Kubo, Hirotaka; Takenaga, Hidenobu; Bakhtiari, M.; Ide, Shunsuke; Kondoh, Takashi; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.593 - 601, 2005/08

An experiment to investigate mitigation effects of impurity pellet injection on disruption generated runaway electrons was carried out in the JT-60U tokamak device. Deposition of impurity neon pellets into a post-disruption runaway plasma was observed with increment of bulk electron density. At the impurity pellet injection, decay time of runaway current became shorter as factor of $$sim$$2. There was an approximately linear relationship between changes in decay rate of runaway current and a photo-neutron signal which indicated loss of runaway electrons from the plasma. Consequently, enhanced loss of runaway electrons from a tokamak plasma, hence mitigation effect on them, by injection of impurity neon pellets was found.

Journal Articles

Study of plasma termination using high-Z noble gas puffing in the JT-60U tokamak

Bakhtiari, M.; Tamai, Hiroshi; Kawano, Yasunori; Kramer, G. J.*; Isayama, Akihiko; Nakano, Tomohide; Kamiya, Kensaku; Yoshino, Ryuji; Miura, Yukitoshi; Kusama, Yoshinori; et al.

Nuclear Fusion, 45(5), p.318 - 325, 2005/05

 Times Cited Count:44 Percentile:78.77(Physics, Fluids & Plasmas)

In the previous works we had shown that injecting a mixture of large amounts of hydrogen and small amounts of argon can terminate a tokamak discharge quickly with avoiding runaway electron generation. In this work we have done the same experiments but with different gases in addition to argon. In fact we compared the effect of the puffing of argon, krypton, and xenon gases with and without simultaneous hydrogen gas puffing on disruption mitigation. We observed that injecting all impurities in the form of an admixture in hydrogen lead to faster plasma shutdowns with less runaway electron generation. We also found that injecting krypton gas (with or without hydrogen) seems to be a good candidate for plasma shutdown purposes since it induces low heat flux to divertor plates and avoids runaway electron generation more effectively.

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meeting, 13

Kawano, Yasunori; Kawahata, Kazuo*; Kusama, Yoshinori; Sasao, Mamiko*; Sugie, Tatsuo; Mase, Atsushi*; Asakura, Nobuyuki; Kato, Takako*; Takamura, Shuichi*; Tanabe, Tetsuo*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 81(2), p.128 - 130, 2005/02

no abstracts in English

35 (Records 1-20 displayed on this page)