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Journal Articles

Localized tungsten deposition in divertor region in JT-60U

Ueda, Yoshio*; Fukumoto, Masakatsu*; Watanabe, Jun*; Otsuka, Yusuke*; Arai, Takashi; Asakura, Nobuyuki; Nobuta, Yuji*; Sato, Masayasu; Nakano, Tomohide; Yagyu, Junichi; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

Deposition profiles of tungsten released from the outer divertor were studied in JT-60U. A neutron activation method was used for the first time to accurately measure deposited tungsten. Surface density of tungsten in the thick carbon deposition layer can be measured by this method. Tungsten was mainly deposited on the inner divertor (around inner strike points) and on the outer wing of the dome. Toroidal distribution of the W deposition was significantly localized near the tungsten released position, while other metallic impurities such as Fe, Cr, Ni were distributed more uniformly. These data indicate that inward drift in the divertor region played a significant role in tungsten transport in JT-60U.

Journal Articles

Surface studies of tungsten erosion and deposition in JT-60U

Ueda, Yoshio*; Fukumoto, Masakatsu*; Nishikawa, Masahiro*; Tanabe, Tetsuo*; Miya, Naoyuki; Arai, Takashi; Masaki, Kei; Ishimoto, Yuki*; Tsuzuki, Kazuhiro*; Asakura, Nobuyuki

Journal of Nuclear Materials, 363-365, p.66 - 71, 2007/06

 Times Cited Count:9 Percentile:57.83(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Chemical abundances in the secondary star of the black hole binary V4641 Sagittarii (SAX J1819.3-2525)

Sadakane, Kozo*; Arai, Akira*; Aoki, Wako*; Arimoto, Nobuo*; Hidai, Masahide*; Onishi, Takashi*; Tajitsu, Akito*; Beers, T. C.*; Iwamoto, Nobuyuki; Tominaga, Nozomu*; et al.

Publications of the Astronomical Society of Japan, 58(3), p.595 - 604, 2006/06

 Times Cited Count:10 Percentile:31.51(Astronomy & Astrophysics)

We report detailed spectroscopic studies performed for the secondary star in the black hole binary (micro-quasar) V4641 Sgr in order to examine its surface chemical composition and to see if its surface shows any signature of pollution by ejecta from a supernova explosion. We obtain abundances of 10 elements and find definite over-abundances of N (by 0.8 dex or more) and Na (by 0.8 dex) in V4641 Sgr. From line-by-line comparisons of eight other elements (C, O, Mg, Al, Si, Ti, Cr, Fe) between V4641 Sgr and the two normal late B-type stars, which have been reported to have solar abundances. An evolutionary model of a massive close binary system has been constructed to explain the abundances observed in V4641 Sgr. The model suggests that the BH forming supernova in this system was a dark one.

Journal Articles

Thermal properties of redeposition layers in the JT-60U divertor region

Ishimoto, Yuki; Goto, Yoshitaka*; Arai, Takashi; Masaki, Kei; Miya, Naoyuki; Oyama, Naoyuki; Asakura, Nobuyuki

Journal of Nuclear Materials, 350(3), p.301 - 309, 2006/05

 Times Cited Count:20 Percentile:81.23(Materials Science, Multidisciplinary)

Thermal properties of the redeposition layer on the inner plate of the W-shaped divertor of JT-60U have been measured with laser flash method for the first time so as to estimate transient heat loads onto the divertor. Measurement of a redeposition layer sample of more than 200 m thick showed following results: (1) the bulk density of the redeposition layer is about half of that of carbon fiber composite material; (2) the specific heat of the layer is roughly equal to that of the isotropic graphite; (3) the thermal conductivity of the redeposition layer is two orders of magnitude smaller than that of the carbon fiber composite. The difference between the divertor heat loads and the loss of the plasma stored energy becomes smaller taking account of thermal properties of the redeposition layer on the inner divertor, whereas estimated heat loads due to the ELMs is still larger than the loss. This is probably caused by the poloidal distribution of the thermal properties and heat flux asymmetry inherent in the device.

Journal Articles

Boronization effects using deuterated-decaborane (B$$_{10}$$D$$_{14}$$) in JT-60U

Nakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Yagyu, Junichi; Arai, Takashi; Asakura, Nobuyuki; Itami, Kiyoshi

Journal of Nuclear Materials, 313-316(1-3), p.149 - 152, 2003/03

 Times Cited Count:28 Percentile:86.45(Materials Science, Multidisciplinary)

In JT-60U, boronization using hydride-decaborane (B$$_{10}$$D$$_{14}$$) was performed to reduce oxygen impurity and particle recycling. A problem of the boronization was that hydrogen originating from hydride-decaborane diluted core deuterium plasmas. In order to minimize the number of conditioning tokamak discharges, boronization using deuterated-decaborane (B$$_{10}$$D$$_{14}$$) has been introduced recently. In order to investigate durability of the boronization effects, discharges with an identical condition were repeated. Boronization using 20 g of deuterated-decaborane could reduce a core oxygen content from $$sim$$ 1.9% to only $$sim$$ 1.3% in L-mode discharges with a neutral beam heating power of $$sim$$ 4 MW. Boronization using 70 g of deuterated-decaborane reduced the core oxygen content from $$sim$$ 2.2% to $$sim$$ 0.5%. After the boronization using 70 g of deuterated-decaborane ( thickness of the Boron layer $$sim$$ 135 nm ), the core oxygen content increased gradually from $$sim$$ 0.5% to $$sim$$ 1% in $$sim$$ 400 shots.

Journal Articles

First test results for the ITER central solenoid model coil

Kato, Takashi; Tsuji, Hiroshi; Ando, Toshinari; Takahashi, Yoshikazu; Nakajima, Hideo; Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Kawano, Katsumi; Oshikiri, Masayuki*; et al.

Fusion Engineering and Design, 56-57, p.59 - 70, 2001/10

 Times Cited Count:17 Percentile:76.5(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Progress of the ITER central solenoid model coil programme

Tsuji, Hiroshi; Okuno, Kiyoshi*; Thome, R.*; Salpietro, E.*; Egorov, S. A.*; Martovetsky, N.*; Ricci, M.*; Zanino, R.*; Zahn, G.*; Martinez, A.*; et al.

Nuclear Fusion, 41(5), p.645 - 651, 2001/05

 Times Cited Count:55 Percentile:84.47(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

An Investigation of methods for neutron dose measurement in high temperature irradiation fields

Kosako, Toshiso*; Sugiura, Nobuyuki*; Kudo, Kazuhiko*; Mori, Chizuo*; Iimoto, Takeshi*; Shikama, Tatsuo*; Katagiri, Masaki; Hayashi, Kimio; Aihara, Jun; Shibata, Taiju; et al.

JAERI-Review 2000-017, 78 Pages, 2000/10

JAERI-Review-2000-017.pdf:4.62MB

no abstracts in English

Journal Articles

Development of short-circuit detecting system for toroidal field coil in JT-60

Miyata, Katsuyuki*; Yagyu, Junichi; Miyo, Yasuhiko; *; Arai, Takashi; Miyachi, Kengo; Hosogane, Nobuyuki

KEK Proceedings 99-17 (CD-ROM), 4 Pages, 1999/00

no abstracts in English

Journal Articles

Initial boronization of JT-60U tokamak using decaborane

Saido, Masahiro; Ogiwara, Norio; Shimada, Michiya; Arai, Takashi; Hiratsuka, Hajime; ; Shimizu, Masatsugu; Ninomiya, Hiromasa; Nakamura, Hiroo; *; et al.

Japanese Journal of Applied Physics, 32(7), p.3276 - 3281, 1993/07

 Times Cited Count:54 Percentile:90.71(Physics, Applied)

no abstracts in English

Journal Articles

Hydrogen/deuterium recycling and initial results of helium ash study in JT-60U

Nakamura, Hiroo; Sakasai, Akira; Shimada, Michiya; Yoshino, Ryuji; Arai, Takashi; Fukuda, Takeshi; Hirayama, Toshio; Hosogane, Nobuyuki; Ishida, Shinichi; Kaminaga, Atsushi; et al.

Journal of Nuclear Materials, 196-198, p.642 - 646, 1992/00

 Times Cited Count:3 Percentile:36.08(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Density control for getting stable discharges in JT-60 graphite wall experiment

Yoshino, Ryuji; Neyatani, Yuzuru; Ninomiya, Hiromasa; Hosogane, Nobuyuki; Nakamura, Hiroo; Arai, Takashi; Itami, Kiyoshi; *; Sato, Masayasu; Fukuda, Takeshi; et al.

Journal of Nuclear Materials, 162-164, p.527 - 532, 1989/00

 Times Cited Count:3 Percentile:42.61(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

The JT-60 tokamak machine

Ota, Mitsuru; Abe, Tetsuya; ; Ando, Toshiro; Arai, Takashi; *; Hiratsuka, Hajime; ; Hosogane, Nobuyuki; ; et al.

Fusion Engineering and Design, 5, p.27 - 46, 1987/00

 Times Cited Count:5 Percentile:51.41(Nuclear Science & Technology)

no abstracts in English

Oral presentation

Study of carbon impurity transport in JT-60U Using $$^{13}$$CH$$_{4}$$ gas puffing

Ishimoto, Yuki; Goto, Yoshitaka*; Arai, Takashi; Masaki, Kei; Miya, Naoyuki; Tsuzuki, Kazuhiro; Asakura, Nobuyuki; Tanabe, Tetsuo*

no journal, , 

no abstracts in English

Oral presentation

Transport studies of carbon impurities using $$^{13}$$CH$$_{4}$$ gas puffing in JT-60U

Ishimoto, Yuki; Goto, Yoshitaka*; Arai, Takashi; Masaki, Kei; Miya, Naoyuki; Tsuzuki, Kazuhiro; Asakura, Nobuyuki; Tanabe, Tetsuo*

no journal, , 

no abstracts in English

Oral presentation

Redeposition distribution of tungsten eroded from the tungsten coated divertor tiles in JT-60U

Fukumoto, Masakatsu*; Otsuka, Yusuke*; Ueda, Yoshio*; Tanabe, Tetsuo*; Sakasai, Akira; Masaki, Kei; Arai, Takashi; Yagyu, Junichi; Nobuta, Yuji; Kubo, Hirotaka; et al.

no journal, , 

no abstracts in English

Oral presentation

U-238 M$"o$ssbauer spectroscopic study of uranium oxysulfide

Masaki, Nobuyuki; Nakada, Masami; Akabori, Mitsuo; Arai, Yasuo; Nakamura, Akio; Sato, Nobuaki*

no journal, , 

The U-238 M$"o$ssbauer effect of uranium oxysulfide, UOS, has been investigated at various temperatures from 19 K to 80 K. The $$gamma$$-ray source used for U-238 M$"o$ssbauer spectroscopy was Pu-242 dioxide with high isotope purity. By using a pure Ge detector, the 44.9 keV U-238 M$"o$ssbauer $$gamma$$-ray is easily distinguished from the 59.5 keV $$gamma$$-ray of the Am-241 isotope, which is the daughter nucleus of the isotopic impurity Pu-241. Quadrupole splitting of the U-238 nucleus in UOS is approximately -40 mm/s in the temperature range without account of magnetic splitting. According to neutron diffraction and magnetic susceptibility measurements, UOS is antiferromagnetic at low temperatures with a Neel temperature of T$$_{N}$$ = 55 K. However, M$"o$ssbauer spectra below 55 K could be analyzed by using only quadrupole splitting without magnetic splitting. This result showed that the magnitude of quadrupole splitting was much larger than that of magnetic splitting of U nucleus in UOS.

Oral presentation

Tungsten deposition distribution in divertor region in JT-60U

Watanabe, Jun*; Fukumoto, Masakatsu*; Soga, Yasuyuki*; Otsuka, Yusuke*; Ueda, Yoshio*; Arai, Takashi; Asakura, Nobuyuki; Nakano, Tomohide; Sato, Masayasu; Yagyu, Junichi; et al.

no journal, , 

Tungsten was mainly deposited on the inner divertor (around the inner strike point) and the outer wing of the dome. Tungsten deposition on the dome was found only near the top surface (within depth of a few micron m), while tungsten on the inner divertor was codeposited with carbon to the depth up to about 60 micron m. Discussion on the relation between depth distribution of tungsten and EDX signals are also presented. Significant difference between tungsten and other metallic materials (Fe, Ni, Cr) in terms of toroidal deposition distribution on the outer wing was observed. Tungsten deposition was toroidally localized in the P-8 section, where tungsten coated tiles were installed. On the other hand, other metallic materials (Fe, Ni, Cr) were not toroidally localized compared with the case of tungsten.

Oral presentation

U-238 M$"o$ssbauer spectra of uranium oxysulfide

Masaki, Nobuyuki; Nakada, Masami; Akabori, Mitsuo; Arai, Yasuo; Nakamura, Akio; Sato, Nobuaki*

no journal, , 

no abstracts in English

Oral presentation

Deposition profile of Tungsten in JT-60U

Watanabe, Jun*; Fukumoto, Masakatsu*; Soga, Yasuyuki*; Otsuka, Yusuke*; Ueda, Yoshio*; Asakura, Nobuyuki; Arai, Takashi; Nakano, Tomohide; Sato, Masayasu; Yagyu, Junichi; et al.

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)