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Journal Articles

Characterization of Type-I ELMs in tangential co-, balanced- and counter-plus perpendicular NBI heated plasmas on JT-60U

Kamiya, Kensaku; Urano, Hajime; Koide, Yoshihiko; Takizuka, Tomonori; Oyama, Naoyuki; Kamada, Yutaka; JT-60 Team

Plasma Physics and Controlled Fusion, 48(5A), p.A131 - A139, 2006/05

 Times Cited Count:20 Percentile:40.59(Physics, Fluids & Plasmas)

Effects of plasma rotation and ripple loss on the Type-I ELMs have systematically studied in the JT-60U tokamak, scanning combinations of NBI at the three kinds of plasma volumes. New findings on the Type-I ELMs confirm to be smaller ELM energy loss per pedestal stored energy, DWELM/Wped, and faster ELM frequency, fELM, in the counter-NBI than co-NBI, keeping the power of ELM, PELM, per heating power crossing the separatrix, PSEP, constant. Balanced-NBI case is also intermediate between co- and counter-NBI. In addition, the product of PELM/PSEP decreases according to increase in the plasma volume, suggesting an increase in the inter-ELM transport due mainly to an enhancement in the ripple loss of fast ion.

Journal Articles

Ripple reduction with ferritic insert in JFT-2M

Shinohara, Koji; Sato, Masayasu; Kawashima, Hisato; Tsuzuki, Kazuhiro; Suzuki, Sadaaki; Urata, Kazuhiro*; Isei, Nobuaki; Tani, Takashi; Kikuchi, Kazuo; Shibata, Takatoshi; et al.

Fusion Science and Technology, 49(2), p.187 - 196, 2006/02

 Times Cited Count:7 Percentile:51.25(Nuclear Science & Technology)

In JFT-2M, the toroidal field ripple was reduced by ferritic insert. Two kinds of ripple reduction were carried out. In the first case, ferritic steel was installed between toroidal field coil and vacuum vessel, just under toroidal field coil, outside vacuum vessel. In the second one, ferritic steel was installed inside vacuum vessel covering almost whole inside wall. The ripple was successfully reduced in the both cases. The temperature increment on the first wall measured by infrared TV was also reduced. A new version of OFMC code was also developed to analyze fast ion behavior in the complex structure of the toroidal field. The TF ripple reduction with ferritic insert in JFT-2M is summarized in this article.

Journal Articles

Deuterium depth profiling in JT-60U W-shaped divertor tiles by nuclear reaction analysis

Hayashi, Takao; Ochiai, Kentaro; Masaki, Kei; Goto, Yoshitaka*; Kutsukake, Chuzo; Arai, Takashi; Nishitani, Takeo; Miya, Naoyuki

Journal of Nuclear Materials, 349(1-2), p.6 - 16, 2006/02

 Times Cited Count:10 Percentile:39.34(Materials Science, Multidisciplinary)

Deuterium concentrations and depth profiles in plasma-facing graphite tiles used in the divertor of JT-60U were investigated by NRA. The highest deuterium concentration of D/$$^{12}$$C of 0.053 was found in the outer dome wing tile, where the deuterium accumulated probably through the deuterium-carbon co-deposition. In the outer and inner divertor target tiles, the D/$$^{12}$$C data were lower than 0.006. Additionally, the maximum (H+D)/$$^{12}$$C in the dome top tile was estimated to be 0.023 from the results of NRA and SIMS. OFMC simulation showed energetic deuterons caused by NBI were implanted into the dome region with high heat flux. Furthermore, the surface temperature and conditions such as deposition and erosion significantly influenced the accumulation process of deuterium. The deuterium depth profile, SEM observation and OFMC simulation indicated the deuterium was considered to accumulate through three processes: the deuterium-carbon co-deposition, the implantation of energetic deuterons and the deuterium diffusion into the bulk.

Journal Articles

Trailing the hydrogen isotopes in the nuclear fusion device

Masaki, Kei

Nippon Genshiryoku Gakkai-Shi, 46(12), p.834 - 837, 2004/12

no abstracts in English

JAEA Reports

Fast ion loss calculation in the ripple compensation magnetic field by ferritic steel insertion using the FEMAG/OFMC code

Urata, Kazuhiro*; Shinohara, Koji; Suzuki, Masanobu*; Kamata, Isao*

JAERI-Data/Code 2004-007, 45 Pages, 2004/03

JAERI-Data-Code-2004-007.pdf:5.63MB

As the toroidal magnetic field generated by discrete TF coils involves magnetic field ripple, the fast ion loss is induced to damage vacuum vessel in tokamaks. An idea of ripple compensation using ferromagnetic is proposed. Since low activation ferritic steel have low activation and thermal conduction properties, the ferritic steel is planned to install in tokamak reactors. Installation of ferritic steel plates with toroidal symmetry is effective to compensate ripple, however in the actual devices it is difficult for interference with other components. Besides the first wall shapes are often asymmetric. So it is better to treat toroidal asymmetry to evaluate the ripple induced loss in the actual devices. For the purpose, magnetic field calculation code considering ferritic steel; FEMAG(FErrite generating MAGnetic field)has been speeded up. On the basis of this magnetic field data, OFMC (Orbit Following Monte Carlo) has been upgraded to treat toroidal asymmetry. The use of FEMAG/OFMC, applications to the JFT-2M experiments, and the national centralized tokamak facility are reported.

Journal Articles

Tritium behavior in JT-60

Masaki, Kei

Kaku Yugoro, (11), p.30 - 33, 2004/03

no abstracts in English

Journal Articles

Effects of complex magnetic ripple on fast ions in JFT-2M ferritic insert experiments

Shinohara, Koji; Kawashima, Hisato; Tsuzuki, Kazuhiro; Urata, Kazuhiro*; Sato, Masayasu; Ogawa, Hiroaki; Kamiya, Kensaku; Sasao, Hajime; Kimura, Haruyuki; Kasai, Satoshi; et al.

Nuclear Fusion, 43(7), p.586 - 593, 2003/07

 Times Cited Count:45 Percentile:19.34(Physics, Fluids & Plasmas)

In JFT-2M, the ferritic steel was installed inside the vacuum vessel as the third step of tne Advanced Material Tokamak Experiment (AMTEX) programme. The magnetic field structure has become the complex ripple strucuture such as non-periodic ripple structure in the toroidal direction and high Fourier-number ripple because of the existence of the port and the limitation of the periodic installation. Under such a complex ripple structure, we have performed the experiment to understand its effect on fast ions. To actively change the ripple structure, we have installed the additional ferritic steel plates (FPs). We also have compared the experiment result with the newly updated OFMC code which does not need the toroidal 16-folded symmetry. The experiment results were almost consistent with the OFMC calcution with the complex magnetic field and the complex first wall.

JAEA Reports

Development of FEMAG; Calculation code of magnetic field generated by ferritic plates in the tokamak devices

Urata, Kazuhiro*

JAERI-Data/Code 2003-005, 36 Pages, 2003/03

JAERI-Data-Code-2003-005.pdf:2.96MB

In design of the fusion devises in which ferritic steel is planned to use as the plasma facing material and/or the inserts for ripple reduction, the appreciation of the error field effect and the optimization of ferritic plate arrangement to reduce the toroidal field ripple require calculation of ferritic magnetic field. However iterative calculations by the non-linearity in B-H curve disturbs high-speed calculation. In the strong toroidal magnetic field in the tokamak, fully magnetic saturation of ferritic steel occurs. Hence a distribution of magnetic charges as magnetic field source is determined straightforward. Additionally objective ferritic steel geometry is limited to the thin plate and they are installed along the toroidal magnetic field. Taking them into account, high-speed calculation code FEMAG has been developed. In this report, the formalization of FEMAG, how to use FEMAG, and the validity check in comparison with a 3D FEM code, with the measurements of the magnetic field in JFT-2M are described. The presented examples are design studies for JT-60 modification.

Journal Articles

Investigation on ripple loss reduction by ferritic steel plate insertion in JFT-2M; Comparison between experimental and computational data

Sato, Masayasu; Kimura, Haruyuki; Miura, Yukitoshi; Nakayama, Takeshi*; Tobita, Kenji; Kawashima, Hisato; Tsuzuki, Kazuhiro; Isei, Nobuaki

Nuclear Fusion, 42(8), p.1008 - 1013, 2002/08

 Times Cited Count:4 Percentile:84.45(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Monte Carlo simulation of particle and heat transport in internal transport barrier

Hamamatsu, Kiyotaka; Takizuka, Tomonori; Shirai, Hiroshi; Kishimoto, Yasuaki; C.S.Chang*

Europhysics Conference Abstracts (CD-ROM), 23J, p.421 - 424, 1999/00

no abstracts in English

Journal Articles

Production and confinement characteristics of ICRF-accelerated energetic ions in JT-60U negative-shear plasmas

Kusama, Yoshinori; Kimura, Haruyuki; Nemoto, Masahiro; Hamamatsu, Kiyotaka; Tobita, Kenji; Oikawa, Toshihiro; Afanassiev, V. I.*; Morioka, Atsuhiko; Fujita, Takaaki; Koide, Yoshihiko; et al.

Plasma Physics and Controlled Fusion, 41(5), p.625 - 643, 1999/00

 Times Cited Count:5 Percentile:79(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Numerical analysis of helium ash removal by using ICRH-driven ripple transport

Hamamatsu, Kiyotaka; C.S.Chang*; Takizuka, Tomonori; Azumi, Masafumi; Hirayama, Toshio; S.Cohen*; *

Plasma Physics and Controlled Fusion, 40(2), p.255 - 270, 1998/00

 Times Cited Count:8 Percentile:69.64(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Benchmarking of the NBI block in ASTRA code versus the OFMC calculations

A.Polevoi*; Shirai, Hiroshi; Takizuka, Tomonori

JAERI-Data/Code 97-014, 14 Pages, 1997/03

JAERI-Data-Code-97-014.pdf:0.65MB

no abstracts in English

Journal Articles

Removal of helium ash and impurities by using ICRH driven ripple transport

Hamamatsu, Kiyotaka; C.S.Chang*; Takizuka, Tomonori; Azumi, Masafumi; Hirayama, Toshio; S.Cohen*; Tani, Keiji

Fusion Energy 1996, 2, p.683 - 691, 1997/00

no abstracts in English

Journal Articles

Ripple induced fast ion loss and related effects in JT-60U

Tobita, Kenji; Tani, Keiji; Kusama, Yoshinori; Nishitani, Takeo; Ikeda, Yoshitaka; Neyatani, Yuzuru; S.V.Konovalov*; Kikuchi, Mitsuru; Koide, Yoshihiko; Hamamatsu, Kiyotaka; et al.

Nuclear Fusion, 35(12), p.1585 - 1591, 1995/00

 Times Cited Count:60 Percentile:12.24(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Analysis of high energy ion ripple loss in the up-down asymmetric configuration by OFMC plus mapping hybrid code

Konovalov, S.*; Takizuka, Tomonori; Tani, Keiji; Hamamatsu, Kiyotaka; Azumi, Masafumi

JAERI-Research 94-033, 25 Pages, 1994/11

JAERI-Research-94-033.pdf:0.95MB

no abstracts in English

Journal Articles

Fast ion losses due to toroidal field ripple in JT-60U

Tobita, Kenji; Tani, Keiji; Nishitani, Takeo; Nagashima, Keisuke; Kusama, Yoshinori

Nuclear Fusion, 34(8), p.1097 - 1109, 1994/00

 Times Cited Count:48 Percentile:18.01(Physics, Fluids & Plasmas)

no abstracts in English

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