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Takizuka, Tomonori; Hosokawa, Masanari*
Contributions to Plasma Physics, 46(7-9), p.698 - 703, 2006/09
Times Cited Count：14 Percentile：43.82(Physics, Fluids & Plasmas)Enhanced heat and particle fluxes to the divertor plates after an ELM crash in H-mode plasmas are the crucial issues for the tokamak reactor operation. Kinetic effect in the transient behaviour of SOL-divertor plasmas for this case is not yet well known. We investigate above problems with an advanced particle simulation code, PARASOL. Dependence of the particle and heat propagations on the collisionality is studied systematically. Effect of the particle recycling is also studied.
Nakano, Tomohide; Asakura, Nobuyuki; Takenaga, Hidenobu; Kubo, Hirotaka; Miura, Yukitoshi; Shimizu, Katsuhiro; Konoshima, Shigeru; Masaki, Kei; Higashijima, Satoru; JT-60 Team
Nuclear Fusion, 46(5), p.626 - 634, 2006/05
Times Cited Count：21 Percentile：57.18(Physics, Fluids & Plasmas)In order to understand plasma-wall interactions in a long time scale, the discharge pulse length has been extended from 15 s to 65 s, with the NB-heating duration extended to 30 s. Nearly-saturation of the divertor plates was observed in the latter half of long pulse ELMy H-mode discharges. Particle sink into the divertor plates gradually decreased, and subsequently, wall-pumping efficiency became zero. This wall saturation resulted in a rise of the main plasma density without any auxiliary particle supply besides NB with divertor-pumping. Even when the total injected energy reached up to 
350 MJ in a discharge, neither sudden increase of carbon generation such as carbon bloom nor increase of the dilution of the main plasma was observed.
Suzuki, Satoshi; Ezato, Koichiro; Hirose, Takanori; Sato, Kazuyoshi; Yoshida, Hajime; Enoeda, Mikio; Akiba, Masato
Fusion Engineering and Design, 81(1-7), p.93 - 103, 2006/02
Times Cited Count：12 Percentile：63(Nuclear Science & Technology)This paper presents an R&D activity on the plasma facing components (PFCs), such as first wall and divertor, for the fusion power plant. The PFCs of the power plant will be subjected to heavy neutron irradiation and high heat/particle flux from plasma during the continuous operation. In the present design of the PFCs, the candidate structural material is a reduced activation ferritic-martensitic steel, F82H, from the viewpoints of low activation and high robustness against neutron irradiation, and the candidate armor material is tungsten from the low sputtering yield and low tritium retention points of view. To realize the PFCs using such materials, JAERI has bee extensively conducting R&Ds on; (1) high performance cooling tube, (2) tungsten armor materials, (3) selection of a bonding technique for F82H and tungsten materials and (4) evaluation of structural integrity. Recent achievements on these R&Ds are presented.
Kawashima, Hisato; Sengoku, Seio; Uehara, Kazuya; Tamai, Hiroshi; Shoji, Teruaki*; Ogawa, Hiroaki; Shibata, Takatoshi; Yamamoto, Masahiro*; Miura, Yukitoshi; Kusama, Yoshinori; et al.
Fusion Science and Technology, 49(2), p.168 - 186, 2006/02
Times Cited Count：3 Percentile：24.08(Nuclear Science & Technology)Experimental efforts on JFT-2M have been devoted to understand SOL/Divertor plasmas and to investigate power and particle controllability. Open divertor configuration was used for the first decade of JFT-2M started in 1984. We found out the SOL/Divertor plasma properties such as in/out asymmetry, heat and particle diffusivities, and SOL current at ELMs. Handling of power and particle was demonstrated by active control methods such as local pumping, edge ergodization, divertor biasing, and edge heating. For improvement of power and particle control capability of divertor, it was modified to closed configuration in 1995, which demonstrated the baffling effects with narrower divertor throat. Dense and cold divertor state (n
= 4
10
m
and T = 4 eV), compatible with the improved confinement modes (e.g. H-mode), was realized by strong gas puffing. Being related with the core confinement at H-mode, the edge plasma fluctuations were identified by an electrostatic probe. These are reviewed in this paper.
Kubo, Hirotaka; JT-60 Team
Plasma Science and Technology, 8(1), p.50 - 54, 2006/01
Times Cited Count：2 Percentile：7.04(Physics, Fluids & Plasmas)no abstracts in English
Kusakabe, Toshio*; Shiota, Kenji*; Kubo, Hirotaka; Shirai, Toshizo*
Journal of Plasma and Fusion Research SERIES, Vol.7, p.237 - 239, 2006/00
no abstracts in English
ions with excited H atomsShimakura, Noriyuki*; Homma, Mayumi*; Kubo, Hirotaka
Journal of Plasma and Fusion Research SERIES, Vol.7, p.199 - 202, 2006/00
no abstracts in English
plasma operationTamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.
Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12
Times Cited Count：15 Percentile：45.44(Physics, Fluids & Plasmas)Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.
Kubo, Hirotaka; Takenaga, Hidenobu; Sawada, Keiji*; Nakano, Tomohide; Kobayashi, Shinji*; Higashijima, Satoru; Asakura, Nobuyuki; Shimizu, Katsuhiro
Journal of Nuclear Materials, 337-339, p.161 - 165, 2005/03
Times Cited Count：16 Percentile：71.76(Materials Science, Multidisciplinary)no abstracts in English
Shimada, Michiya; Costley, A. E.*; Federici, G.*; Ioki, Kimihiro*; Kukushkin, A. S.*; Mukhovatov, V.*; Polevoi, A. R.*; Sugihara, Masayoshi
Journal of Nuclear Materials, 337-339, p.808 - 815, 2005/03
Times Cited Count：65 Percentile：96.47(Materials Science, Multidisciplinary)ITER is an experimental fusion reactor for investigation and demonstration of burning plasmas, characterised of its heating dominated by alpha-particle heating. ITER is a major step from present devices and an indispensable step for fusion reactor development. ITER's success largely depends on the control of plasma-wall interactions(PWI), with power and particle fluxes and time scales one or two orders of magnitude larger than in present devices. The strategy for control of PWI includes the semi-closed divertor, strong fuelling and pumping, disruption and ELM control, replaceable plasma-facing materials and stepwise operation.
spectral bands for hydrocarbon-loss-events measured in JT-60U divertor plasmasNakano, Tomohide; Tsuzuki, Kazuhiro; Higashijima, Satoru; Kubo, Hirotaka; Asakura, Nobuyuki
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
Emission rates of CH and C
spectral bands for CH
, CD
_2
loss events due to dissociation, ionization and transport were measured in JT-60U divertor plasmas. The obtained data were used for estimating the chemical sputtering yields by a spectroscopic technique. The CH loss events over one CH photon emission was about 200 at electron temperatures between 30 eV and 70 eV. These values fell within the confidential band of the CD one. The CH
loss events over one CH and one C photon emission were, respectively, between 200 - 300 and between 600 - 1800, and their ratio between 3 - 6. On the assumption that only CH among hydrocarbons generated by chemical sputtering emits the C spectral bands, the intensity of the CH spectral bands originating from CH is inferred from the intensity of C spectral bands multiplied by the obtained ratio, resulting in higher than the measured CH intensity. This result indicates that dominant hydrocarbons generated by the chemical sputtering is not CH but CH.
Kubo, Hirotaka; Takenaga, Hidenobu; Nakano, Tomohide; Higashijima, Satoru; Shimizu, Katsuhiro; Sawada, Keiji*; Kobayashi, Shinji*; JT-60 Team
Nuclear Fusion Research; Springer Series in Chemical Physics, Vol.78, p.121 - 134, 2004/11
no abstracts in English
Ezato, Koichiro
Koon Gakkai-Shi, 30(5), p.248 - 255, 2004/09
no abstracts in English
Miura, Yukitoshi; Hoshino, Katsumichi; Kusama, Yoshinori
Purazuma, Kaku Yugo Gakkai-Shi, 80(8), p.653 - 661, 2004/08
A series of experimental program on the JAERI Fusion Torus-2M (JFT-2M) was completed in March, 2004. In the experimental operation for 21 years since the first plasma on April 27, 1983, many significant results leading the fusion energy research and plasma physics have been produced in researches on high confinement mode (H-mode), heating and current drive, advanced plasma control, compatibility of low activation ferritic steel with improved confinement mode, etc. Among these results, some important results are presented.
Asakura, Nobuyuki
Purazuma, Kaku Yugo Gakkai-Shi, 80(3), p.190 - 200, 2004/03
Understanding of the divertor and Scrape-off Layer (SOL) plasmas has been progressed during improvements of the compact- and closed-geometry tokamak divertors. Developments of new diagnostics viewing the SOL and upstream of the divertor target (with the finest spatial and/or time resolutions) have contributed to understand the physics mechanisms under large variations of the plasma along and perpendicular to the field lines. Four topics: (i) heat and particle transports upstream of the divertor plate, (ii) burst transport of heat and particles towards the divertor, (iii) SOL plasma flow, and (iv) plasma diffusion in SOL, were reviewed.
Shimizu, Katsuhiro; Takizuka, Tomonori
Purazuma, Kaku Yugo Gakkai-Shi, 80(3), p.183 - 189, 2004/03
The history of tokamak experiment is briefly reviewed from a viewpoint of divertor. Two-point divertor model, which calculates plasma parameters at up-stream and divertor plate from particle flux and heat flux, is explained. Applied to ITER, the heat flux onto the target plate is discussed. The basic important divertor physics, for example, recycling, remote radiative cooling, detached plasma and MARFE are also presented.
Smirnov, R.*; Tomita, Yukihiro*; Takizuka, Tomonori; Takayama, Arimichi*; Chutov, Y.*
NIFS-784, 9 Pages, 2003/10
Dynamics of dust particles in a divertor plasma is simulated using numerical solutions of dust momentum and charging equations. Spatial distributions of plasma parameters in a divertor are obtained with particle simulations including electron-impact ionization. We find that the large-radius dust particles are not released from the divertor plate. The middle-size-radius particles are released but retuned to the plate. The small-radius particles can be released from the plate.
Suzuki, Satoshi; Ueda, Yoshio*; Tokunaga, Kazutoshi*; Sato, Kazuyoshi; Akiba, Masato
Fusion Science and Technology, 44(1), p.41 - 48, 2003/07
Times Cited Count：28 Percentile：84.95(Nuclear Science & Technology)no abstracts in English
Takizuka, Tomonori; Arakawa, Kazuya*; Shimizu, Katsuhiro; Hayashi, Nobuhiko; Asakura, Nobuyuki
JAERI-Research 2003-010, 57 Pages, 2003/05
JAERI-Research-2003-010.pdf:4.59MB
no abstracts in English
Kubo, Hirotaka; Sakurai, Shinji; Higashijima, Satoru; Takenaga, Hidenobu; Itami, Kiyoshi; Konoshima, Shigeru; Nakano, Tomohide; Koide, Yoshihiko; Asakura, Nobuyuki; Shimizu, Katsuhiro; et al.
Journal of Nuclear Materials, 313-316(1-3), p.1197 - 1201, 2003/03
Times Cited Count：20 Percentile：75.71(Materials Science, Multidisciplinary)no abstracts in English
