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Tani, Keiji*; Honda, Mitsuru; Oikawa, Toshihiro*; Shinohara, Koji; Kusama, Yoshinori; Sugie, Tatsuo
Nuclear Fusion, 55(5), p.053010_1 - 053010_15, 2015/05
Times Cited Count:3 Percentile:13.86(Physics, Fluids & Plasmas)The effects of a radial electric field (EF) on the losses of alpha particles and NBI fast ions in typical ITER operation scenarios for both error fields due to test blanket modules (TBMs) and toroidal field (TF) ripple were evaluated using an iterative method to execute an orbit-following Monte-Carlo code and a one-dimensional transport code. The EF effect on the loss of fast ions strongly depends on the operation scenario as well as on the error field. The electric field is very significant in the loss of fast ions in a 9MA ITER operation scenario with a higher safety factor and in the error field associated with TBMs. The EF effect in the error field of TF-ripple is very small in any operation scenario. The radial electric field changes the toroidal precession of fast ions and consequently alter their condition of resonance with the error field, which may account for the EF effect on the loss of fast ions in ITER with TBMs.
Shinohara, Koji; Tani, Keiji*; Oikawa, Toshihiro*; Putvinski, S.*; Schaffer, M.*; Loarte, A.*
Nuclear Fusion, 52(9), p.094008_1 - 094008_12, 2012/09
Times Cited Count:19 Percentile:64.74(Physics, Fluids & Plasmas)Tani, Keiji*; Shinohara, Koji; Oikawa, Toshihiro*; Tsutsui, Hiroaki*; Miyamoto, Seiji; Kusama, Yoshinori; Sugie, Tatsuo
Nuclear Fusion, 52(1), p.013012_1 - 013012_21, 2012/01
Times Cited Count:31 Percentile:78.81(Physics, Fluids & Plasmas)Murakami, Masanori*; Park, J. M.*; Giruzzi, G.*; Garcia, J.*; Bonoli, P.*; Budny, R. V.*; Doyle, E. J.*; Fukuyama, Atsushi*; Hayashi, Nobuhiko; Honda, Mitsuru; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Shinohara, Koji; Oikawa, Toshihiro; Urano, Hajime; Oyama, Naoyuki; Lnnroth, J.*; Saibene, G.*; Parail, V.*; Kamada, Yutaka
Fusion Engineering and Design, 84(1), p.24 - 32, 2009/01
Times Cited Count:25 Percentile:83.37(Nuclear Science & Technology)Giruzzi, G.*; Park, J. M.*; Murakami, M.*; Kessel, C. E.*; Polevoi, A.*; Sips, A. C. C.*; Artaud, J. F.*; Basiuk, V.*; Bonoli, P.*; Budny, R. V.*; et al.
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
Suzuki, Takahiro; Isayama, Akihiko; Matsunaga, Go; Oyama, Naoyuki; Fujita, Takaaki; Oikawa, Toshihiro
Review of Scientific Instruments, 79(10), p.10F533_1 - 10F533_5, 2008/10
Times Cited Count:8 Percentile:39.29(Instruments & Instrumentation)Motional Stark effect (MSE) diagnostics in JT-60U works as polarimeter to measure the pitch angle of magnetic field as well as beam-emission-spectroscopy (BES) monochromator simultaneously at 30 spatial channels. Fluctuation in the BES signal using MSE optics (MSE/BES) contains fluctuations in not only the density but also the pitch angle (or the magnetic field). Correlation analysis of the magnetic fluctuation between two spatial channels have been applied to a high beta plasma with m/n=2/1 MHD activity at frequency of about 0.9 kHz. It has been found that the magnetic fluctuation measured by the MSE/BES is spatially localized near q=2 surface measured by the MSE diagnostic and that the phase of the fluctuation is inverted at about the q=2 surface, suggesting magnetic island-structure by neo-classical tearing mode (NTM). The magnetic fluctuation measured by the MSE/BES at outside of the q=2 surface is consistent with that by the pick-up coil placed outside the plasma.
Takenaga, Hidenobu; Ogawa, Yuichi*; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 84(7), p.465 - 467, 2008/07
no abstracts in English
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
Suzuki, Takahiro; Ide, Shunsuke; Oikawa, Toshihiro; Fujita, Takaaki; Ishikawa, Masao; Seki, Masami; Matsunaga, Go; Hatae, Takaki; Naito, Osamu; Hamamatsu, Kiyotaka; et al.
Nuclear Fusion, 48(4), p.045002_1 - 045002_9, 2008/04
Times Cited Count:39 Percentile:80.99(Physics, Fluids & Plasmas)Aiming at optimization of current profile in high-b plasmas for higher confinement and stability, a real-time control system of the minimum of the safety factor () using the off-axis current drive has been developed. The off-axis current drive can raise safety factor in the center and help to avoid instability that limits performance of the plasma. The system controls injection power of lower-hybrid (LH) waves, and hence, its off-axis driven current in order to control . The real-time control of is demonstrated in a high- plasma, where follows the temporally changing reference from 1.3 to 1.7. Applying the control to another high- discharge (=1.7, =1.5) with =2/1 neo-classical tearing mode (NTM), was raised above 2 and the NTM was suppressed. The stored energy increased by 16% with the NTM suppressed, since the resonant rational surface was eliminated. For the future use for current profile control, current density profile for off-axis neutral beam current drive (NBCD) is for the first time measured, using motional Stark effect (MSE) diagnostic. Spatially localized NBCD profile was clearly observed at the normalized of about 0.6-0.8. The location was also confirmed by multi-chordal neutron emission profile measurement. The total amount of the measured beam driven current was consistent with the theoretical calculation using the ACCOME code. The CD location in the calculation was inward-shifted than the measurement.
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).
Gormezano, C.*; Sips, A. C. C.*; Luce, T. C.*; Ide, Shunsuke; Becoulet, A.*; Litaudon, X.*; Isayama, Akihiko; Hobirk, J.*; Wade, M. R.*; Oikawa, Toshihiro; et al.
Nuclear Fusion, 47(6), p.S285 - S336, 2007/06
Times Cited Count:302 Percentile:77.19(Physics, Fluids & Plasmas)This paper reviews recent world-wide progress in physics research towards International Thermonuclear Reactor (ITER). This chaper descrives on steady state operation with emphasis on: integrated scenarios, review of presently developed experimental scenarios, actuators for steady state operation, specific control issues to steady state operation, simulation of ITER steady-state and hybrid scenarios.
Suzuki, Takahiro; Ide, Shunsuke; Oikawa, Toshihiro; Fujita, Takaaki; Ishikawa, Masao*; Seki, Masami; Matsunaga, Go; Takechi, Manabu; Naito, Osamu; Hamamatsu, Kiyotaka; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
For the first time, we have measured the current density profile for off-axis neutral beam current drive (NBCD), using motional Stark effect (MSE) diagnostic. A spatially localized NBCD profile was clearly observed at . The location was also confirmed by neutron emission profile measurement. The total amount of the driven current (0.15MA) was consistent with the decrease in the surface loop voltage. The off-axis current drive can raise safety factor (q) in the center and help to avoid instability that limits performance of the plasma. We have developed a real-time control system of the minimum q (qmin), using the off-axis current drive. Injection power of lower hybrid (LH) waves, and hence, its off-axis driven current controls qmin. In a high plasma (, ), the system was adopted to control qmin. With the control, qmin was raised and MHD fluctuations were suppressed. The stored energy increased by 16% with the MHD fluctuations suppressed.
Oikawa, Toshihiro; Shimada, Michiya; Polevoi, A. R.*; Naito, Osamu; Bonoli, P. T.*; Hayashi, Nobuhiko; Kessel, C. E.*; Ozeki, Takahisa
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 7 Pages, 2007/03
The current drive capability of lower hybrid waves is assessed for an ITER steady state scenario using a relativistic, one-dimensional Fokker-Planck code and a toroidal ray tracing code. The present LH launcher design provides a current drive efficiency of 1.810AWm and an off-axis profile of the driven current that is fovarable for a reversed magnetic shear configuration. Possible optimizations in the LH power spectrum are investigated. Neutral beam current drive (NBCD) is investigated with theoretical codes employing different approaches. An NBCD code employing the bounce-averaged Fokker-Planck equation to include orbit effects in a toroidal system shows a good agreement with an orbit following Monte-Carlo code.
Bonoli, P. T.*; Harvey, R. W.*; Kessel, C. E.*; Imbeaux, F.*; Oikawa, Toshihiro; Schneider, M.*; Barbato, E.*; Decker, J.*; Giruzzi, G.*; Forest, C. B.*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
no abstracts in English
Kessel, C. E.*; Giruzzi, G.*; Sips, A. C. C.*; Budny, R. V.*; Artaud, J. F.*; Basiuk, V.*; Imbeaux, F.*; Joffrin, E.*; Schneider, M.*; Luce, T.*; et al.
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
no abstracts in English
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
Suzuki, Takahiro; Fujita, Takaaki; Oyama, Naoyuki; Isayama, Akihiko; Matsunaga, Go; Oikawa, Toshihiro; Asakura, Nobuyuki; Takechi, Manabu
Review of Scientific Instruments, 77(10), p.10E914_1 - 10E914_4, 2006/10
Times Cited Count:7 Percentile:37.66(Instruments & Instrumentation)In JT-60U, we measure temporal evolution (100Hz) of the pitch angles of the magnetic field, using a 30 channel motional Stark effect (MSE) diagnostic with photo-elastic modulators (PEMs). This year, we started acquiring the signal intensity of photo-multipliers (PMs) at 0.5-1MHz sampling for fluctuation profile measurement. Response of the PM (180kHz/-3dB) limits the temporal resolution. The system works as the MSE and the beam emission spectroscopy (BES) diagnostic. Coupling between the MSE and BES signals can provide magnetic fluctuation. Here we report on results in spatially resolved electron density (ne) fluctuation profile measurement in various operation regimes. In the core plasma, ne fluctuation induced by rotating tearing mode islands was observed. Phase of the fluctuations are inverted between higher and lower magnetic field sides, which is consistent with an electron cyclotron emission (ECE) measurement. In the scrape-off layer of an ELMy -mode plasma, outward propagation of strong emission coincides with ELM crash was also observed. The propagation velocity is about 6km/s along the MSE measurement points, where distance between adjacent channels is 6-7cm in the major radius direction. Detailed description of the optics and the system will be presented.
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
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, 82(2), p.109 - 110, 2006/02
no abstracts in English