Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 149

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Effects of the radial electric field on the confinement of fast ions in ITER

Tani, Keiji*; Honda, Mitsuru; Oikawa, Toshihiro*; Shinohara, Koji; Kusama, Yoshinori; Sugie, Tatsuo

Nuclear Fusion, 55(5), p.053010_1 - 053010_15, 2015/05

AA2014-0355.pdf:2.0MB

 Times Cited Count:2 Percentile:11.3(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.

Journal Articles

Effects of rippled fields due to ferritic inserts and ELM mitigation coils on energetic ion losses in a 15 MA inductive scenario in ITER

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:14 Percentile:57.67(Physics, Fluids & Plasmas)

Journal Articles

Effects of ELM mitigation coils on energetic particle confinement in ITER steady-state operation

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:30 Percentile:82.76(Physics, Fluids & Plasmas)

Journal Articles

Integrated modeling of steady-state scenarios and heating and current drive mixes for ITER

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

Journal Articles

Effects of ferromagnetic components on energetic ion confinement in ITER

Shinohara, Koji; Oikawa, Toshihiro; Urano, Hajime; Oyama, Naoyuki; L$"o$nnroth, J.*; Saibene, G.*; Parail, V.*; Kamada, Yutaka

Fusion Engineering and Design, 84(1), p.24 - 32, 2009/01

 Times Cited Count:23 Percentile:84.44(Nuclear Science & Technology)

Journal Articles

Magnetic fluctuation profile measurement using optics of motional stark effect diagnostics in JT-60U

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:41.53(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.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 22

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

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meetings, 21

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

Journal Articles

Off-axis current drive and real-time control of current profile in JT-60U

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:35 Percentile:81.18(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 ($$q$$$$_{rm min}$$) 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 $$q$$$$_{min}$$. The real-time control of $$q$$$$_{rm min}$$ is demonstrated in a high-$$beta$$ plasma, where $$q$$$$_{rm min}$$ follows the temporally changing reference $$q$$$$_{min,ref}$$ from 1.3 to 1.7. Applying the control to another high-$$beta$$ discharge ($$beta$$$$_{rm N}$$=1.7, $$beta$$$$_{rm p}$$=1.5) with $$m/n$$=2/1 neo-classical tearing mode (NTM), $$q$$$$_{rm min}$$ 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 $rm minor radius $rho$$ 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.

Journal Articles

Report of meetings of ITPA (International Tokamak Physics Activity), 19

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).

Journal Articles

Progress in the ITER physics basis, 6; Steady state operation

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:278 Percentile:78.95(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.

Journal Articles

Off-axis current drive and current profile control in JT-60U

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 $$rho=0.6-0.8$$. 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 $$beta$$ plasma ($$beta_{N}=1.7$$, $$beta_{p}=1.5$$), 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.

Journal Articles

Study on current drive capability of lower hybrid waves and neutral beam in an ITER steady state scenario

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 1.8$$times$$10$$^{19}$$AW$$^{-1}$$m$$^{-2}$$ 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.

Journal Articles

Benchmarking of lower hybrid current drive codes with application to ITER-relevant regimes

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

Journal Articles

Simulation of the hybrid and steady state advanced operating modes in ITER

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

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 18

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

Journal Articles

Density fluctuation measurement using motional stark effect optics in JT-60U

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:39.27(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 $$H$$-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.

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meetings, 17

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

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 16

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

Journal Articles

The Basic methods for understanding of plasma equilibrium toward advanced control

Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hosoyama, Hiroki*; Yonekawa, Izuru; Suzuki, Takahiro; Oikawa, Toshihiro; Ide, Shunsuke; JT-60 Team

Fusion Engineering and Design, 74(1-4), p.527 - 536, 2005/11

 Times Cited Count:10 Percentile:55.58(Nuclear Science & Technology)

Since tokamak magnetic fusion research has just made a step forward to an international collaborative project ITER, the existing tokamaks including JT-60 are expected to explore more advanced operation scenarios. To test those scenarios in the JT-60 experiment, the basic methods for understanding of plasma equilibrium have been developed. Some of them have been accomplished, and the other are being conducted as follows: (1) A complete plasma shape is precisely reproduced in real time. (2) Eddy current effects are considered for shape reproduction. (3) A plasma current profile in the poloidal cross-section is reproduced in real. (4) For long-pulse DT operation, a method is developed to correct the drifted signal of the integrator for a pick-up coil by employing distant sensor signals. In the symposium, those methods will be explained in detail with the experimental results at JT-60. On the basis of such discussion, we would like to envisage a future of plasma equilibrium control toward ITER and a fusion power plant.

149 (Records 1-20 displayed on this page)