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Asakura, Nobuyuki
Purazuma, Kaku Yugo Gakkai-Shi, 91(8), P. 566, 2015/08
no abstracts in English
Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; Ogawa, Yuichi*; Takizuka, Tomonori; Takenaga, Hidenobu; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.626 - 627, 2005/08
no abstracts in English
Kallenbach, A.*; Asakura, Nobuyuki; Kirk, A.*; Korotkov, A.*; Mahdavi, M. A.*; Mossessian, D.*; Porter, G. D.*
Journal of Nuclear Materials, 337-339, p.381 - 385, 2005/03
Times Cited Count:67 Percentile:96.50(Materials Science, Multidisciplinary)Edge profile data for H-mode discharges in 6 tokamaks have been analysed with the main focus on the edge density profile as well as electron temperature and density gradient lengths and steep gradient zone widths. A uniform procedure of data treatment and assignment of the separatrix position via power balance allowed to put the multi-machine data on an even base. The machine size appears to be the leading parameter for the width of the steep edge transport barrier gradient zone, as well as for the temperature decay length at the separatrix. Effects associated with neutral penetration physics are visible in the edge density profile.
Roth, J.*; Kirschner, A.*; Bohmeyer, W.*; Brezinsek, S.*; Cambe, A.*; Casarotto, E.*; Doerner, R.*; Gauthier, E.*; Federici, G.*; Higashijima, Satoru; et al.
Journal of Nuclear Materials, 337-339, p.970 - 974, 2005/03
Times Cited Count:96 Percentile:98.47(Materials Science, Multidisciplinary)In the frame work of the EU Task Force on Plasma-Wall Interaction and the International Tokamak Physics Activity an attempt was made to establish a possible dependence of the chemical erosion yield of carbon on the ion flux, , involving ion beam experiments, plasma simulators, and fusion devices. After data normalization a fit using Bayesian probability analysis was performed yielding a decrease of the erosion yield with at high ion fluxes. With this dependence on ion flux a comprehensive description is available for chemical erosion as function of energy, temperature and ion flux. Using this dependence the erosion and redeposition of carbon in the ITER divertor can be calculated using the ERO code and the steady-state plasma scenario given by the ITER team. The resulting gross and net erosion rates are compared to previous estimates using a constant erosion yield of 1.5%. The use of the complete parameter dependence results in an order of magnitude lower erosion, most strongly determined by the temperature dependence and the reduction at the highest fluxes.
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
Roth, J.*; Preuss, R.*; Bohmeyer, W.*; Brezinsek, S.*; Cambe, A.*; Casarotto, E.*; Doerner, R.*; Gauthier, E.*; Federici, G.*; Higashijima, Satoru; et al.
Nuclear Fusion, 44(11), p.L21 - L25, 2004/11
Times Cited Count:97 Percentile:89.66(Physics, Fluids & Plasmas)Chemical erosion of carbon has been studied in ion beam experiments, and the yield values are available as a function of ion energy and surface temperature. ITER divertor condition, however, cannot be simulated by ion beam. For extrapolating to ITER, the erosion must be investigated in plasma simulators and in SOL or divertors of present fusion devices. In the past, erosion values were reported, but the values showed a wide scatter as a function of ion flux, . Therefore, a joint attempt was made through the EU Task Force on Plasma-Wall Interaction and the International Tokamak Physics Activity (ITPA) to clarify the flux dependence. For each data point the local plasma conditions were normalized to impact energy of 30 eV, the data were selected for a surface temperature close to the maximum yield or to room temperature, and the diagnostic was calibrated in-situ. Through this procedure, the previous large scatter could be drastically reduced. A fit using Bayesian probability analysis was performed yielding a decrease of the erosion yield with at high ion fluxes.
Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; Ogawa, Yuichi*; Takizuka, Tomonori; Miura, Yukitoshi; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 80(8), P. 678, 2004/08
no abstracts in English
Kusama, Yoshinori; Kawahata, Kazuo*; Sasao, Mamiko*; Mase, Atsushi*; Sugie, Tatsuo; Kawano, Yasunori; Oyama, Naoyuki; Kamada, Yutaka; Nakashima, Yosuke*; Ida, Katsumi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 80(7), P. 643, 2004/07
no abstracts in English
Asakura, Nobuyuki; Iio, Shunji*; Ozeki, Takahisa; Ono, Yasushi*; Kato, Takako*; Kawano, Yasunori; Sugihara, Masayoshi; Takamura, Shuichi*; Tanabe, Tetsuo*; Nakajima, Noriyoshi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 80(7), P. 642, 2004/07
no abstracts in English
Takizuka, Tomonori; ITPA H-mode Threshold Database Working Group*
Plasma Physics and Controlled Fusion, 46(5A), p.A227 - A233, 2004/05
Times Cited Count:60 Percentile:85.43(Physics, Fluids & Plasmas)To evaluate the H-mode power threshold in future tokamak reactors, quantitative scaling formulas have been developed by using the ITPA threshold database. Recently data from spherical tokamaks (MAST and NSTX) were supplied to the ITPA database. A new scaling expression, which includes the absolute magnetic field B instead of the toroidal magnetic field, subsumes the plasma current dependence at low aspect ratio and is consistent with the previous data without any explicit current dependence. Other possible influence of the low aspect ratio to increase the power threshold is also investigated. It is cralified for the whole data set that the effective charge number Z raises the power threshold. By adding Z as a parameter of the scaling expression, both the scattering nature and the low-density anomaly found in the experimental data can be reduced.
Takizuka, Tomonori
Purazuma, Kaku Yugo Gakkai-Shi, 81(1), p.60 - 61, 2004/01
no abstracts in English
Asakura, Nobuyuki; Kato, Takako*; Takamura, Shuichi*; Tanabe, Tetsuo*; Higashijima, Satoru; Iio, Shunji*; Ozeki, Takahisa; Ono, Yasushi*; Kawano, Yasunori; Nakajima, Noriyoshi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 79(11), p.1194 - 1196, 2003/11
The ITPA (International Tokamak Physics Activity) meeting was held at Scientific Educational Center of Ioffe Institute (St. Petersburg) in Russia. In the meeting, topical physics group meetings of "Scrape-off-layer and Divertor Physics", "MHD, Disruptions and Control", "Energetic Particles, Heating and Steady State Operation", and "Diagnostics" were carried out. The joint meeting for plasma control was also held. In getting many participants from Japan, Europe, Russia, ITER international team, U.S.A. and China (observer), the active discussions were carried out. The outline of discussions in each topical group and in the plasma control joint meeting is reported here.
Takizuka, Tomonori; Ogawa, Yuichi*; Miura, Yukitoshi; Yagi, Masatoshi*; Fujita, Takaaki; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Ida, Katsumi*; ; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 79(6), p.628 - 629, 2003/06
no abstracts in English
Asakura, Nobuyuki
Purazuma, Kaku Yugo Gakkai-Shi, 79(2), P. 193, 2003/02
no abstracts in English
Ide, Shunsuke; Fukuda, Takeshi; Miura, Yukitoshi
Purazuma, Kaku Yugo Gakkai-Shi, 79(2), P. 194, 2003/02
no abstracts in English
Takamura, Shuichi*; Wakatani, Masahiro*; Ninomiya, Hiromasa; Kamada, Yutaka; Yatsu, Kiyoshi*; Hatae, Takaki; Sugihara, Masayoshi; Iio, Shunji*; Ozeki, Takahisa; Kawano, Yasunori
Purazuma, Kaku Yugo Gakkai-Shi, 79(1), P. 70, 2003/01
no abstracts in English
Ninomiya, Hiromasa; Takamura, Shuichi*; Wakatani, Masahiro*; Fujita, Takaaki; Fukuda, Takeshi; Toi, Kazuo*; Ogawa, Yuichi*; Takizuka, Tomonori; Miura, Yukitoshi; Hatae, Takaki; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 78(7), p.692 - 694, 2002/07
The second ITPA (International Tokamak Physics Activity) meeting was held at General Atomics (San Diego) and Princeton Plasma Physics Laboratory (Princeton) in U.S.A. In the meeting, topical physics group meetings of "Coordinating Committee", "Transport and Internal Barrier Physics", "Confinement Database and Modeling", "Edge and Pedestal Physics", "Scrape-off-layer and Divertor Physics", and "Diagnostics" were carried out. In getting many participants from Japan, Europe, Russia, ITER international team and U.S.A., the active discussions were carried out. On the other hand, the topical group members concerned that the contribution from Japan will be decreased if the experimental period of JT-60U is reduced. Here, the outline of discussions in each topical group is reported.
Iio, Shunji*; Ide, Shunsuke; Ozeki, Takahisa; Sugihara, Masayoshi; Takase, Yuichi*; Takeji, Satoru*; Tobita, Kenji; Fukuyama, Atsushi*; Miyamoto, Kenro*
Purazuma, Kaku Yugo Gakkai-Shi, 78(6), P. 601, 2002/06
no abstracts in English
Kawano, Yasunori
no journal, ,
no abstracts in English