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Journal Articles

Designing a prototype of the ITER pulse scheduling system

Yamamoto, Tsuyoshi; Yonekawa, Izuru*; Ota, Kazuya*; Hosoyama, Hiroki*; Hashimoto, Yasunori*; Wallander, A.*; Winter, A.*; Sugie, Tatsuo; Kusama, Yoshinori; Kawano, Yasunori; et al.

Fusion Engineering and Design, 87(12), p.2016 - 2019, 2012/12

 Times Cited Count:2 Percentile:20.56(Nuclear Science & Technology)

The ITER pulse scheduling system creates, approves and manage parameters that characterize plasma operation of ITER. JAEA analyzed requirements on the ITER plasma operations based on experience operating the JT-60U and designed essential functions. This system was designed to enable the change and reuse of parameters. The functions to support to check consistency between parameters and to assign parameter values are calculated by the system were proposed. These functions are useful to support operators.

Journal Articles

Improvement of the real-time processor in JT-60 data processing system

Sakata, Shinya; Kiyono, Kimihiro; Sato, Minoru; Kominato, Toshiharu; Sueoka, Michiharu; Hosoyama, Hiroki; Kawamata, Yoichi

Fusion Engineering and Design, 84(7-11), p.1680 - 1683, 2009/06

 Times Cited Count:1 Percentile:10.95(Nuclear Science & Technology)

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

Control of current profile and instability by radiofrequency wave injection in JT-60U and its applicability in JT-60SA

Isayama, Akihiko; Suzuki, Takahiro; Hayashi, Nobuhiko; Ide, Shunsuke; Hamamatsu, Kiyotaka; Fujita, Takaaki; Hosoyama, Hiroki; Kamada, Yutaka; Nagasaki, Kazunobu*; Oyama, Naoyuki; et al.

AIP Conference Proceedings 933, p.229 - 236, 2007/10

no abstracts in English

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

Advanced data handling for plasma profile control in JT-60

Yonekawa, Izuru; Sueoka, Michiharu; Hosoyama, Hiroki*; Kawamata, Yoichi; Suzuki, Takahiro; Kurihara, Kenichi

Fusion Engineering and Design, 81(15-17), p.1897 - 1903, 2006/07

 Times Cited Count:2 Percentile:18.25(Nuclear Science & Technology)

Recent years, plasma current profile (j-profile) control has been newly proposed to avoid instabilities in the high normalized-beta plasma. In particular, for the real-time profile feedback control, the control period should be roughly less than several tens of ms, including data communication among relating systems. In order to minimize data transfer time,the profile data being a function of time and position is required to decrease its data size for efficient data handling. A profile data,defined as 3-dimension time series data (q,R,Z,t), was reduced by introducing normalized minor radius rho in place of (R,Z). Data handling for profile control will be presented with their technical issues, together with computing hardware engineering.

Journal Articles

Status and prospect of JT-60 plasma control and diagnostic data processing systems for advanced operation scenarios

Kurihara, Kenichi; Yonekawa, Izuru; Kawamata, Yoichi; Sueoka, Michiharu; Hosoyama, Hiroki*; Sakata, Shinya; Oshima, Takayuki; Sato, Minoru; Kiyono, Kimihiro; Ozeki, Takahisa

Fusion Engineering and Design, 81(15-17), p.1729 - 1734, 2006/07

 Times Cited Count:13 Percentile:68.77(Nuclear Science & Technology)

A large tokamak fusion device JT-60 is expected to explore more advanced tokamak discharge scenario towards the ITER and a future power reactor. We believe the following experimental issues are expected to be solved in JT-60. To clarify how to keep a steady-state plasma with high performance, and how to avoid plasma instabilities almost completely. By stimulus of this motivation, several essential development and modifications of plasma control and data acquisition systems have been performed in JT-60. In this report, we discuss the developments to improve the JT-60 plasma control and data acquisition systems. In addition, a future plasma control and data acquisition systems leading to a standard design for a power reactor is envisaged on the basis of the 20-year plasma operation experiences.

JAEA Reports

Development of a profile control system for the JT-60 Plasma equilibrium control

Sueoka, Michiharu; Suzuki, Takahiro; Hosoyama, Hiroki

JAEA-Technology 2006-022, 44 Pages, 2006/03

JAEA-Technology-2006-022.pdf:3.61MB

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.

Journal Articles

Recent RF experiments and application of RF waves to real-time control of safety factor profile in JT-60U

Suzuki, Takahiro; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki; Oikawa, Toshihiro; Sakata, Shinya; Sueoka, Michiharu; Hosoyama, Hiroki*; Seki, Masami; JT-60 Team

AIP Conference Proceedings 787, p.279 - 286, 2005/09

A real-time control system of safety factor (q) profile was developed in JT-60. This system, for the first time, enables 1) real time evaluation of q profile using local magnetic pitch angle measurement by motional Stark effect (MSE) diagnostic and 2) control of current drive (CD) location (rhoCD) by adjusting the parallel refractive index $$N_{rm //}$$ of lower-hybrid (LH) waves through the change of phase difference (dphi) of LH waves between multi-junction launcher modules. The method for q profile evaluation was newly developed, without time-consuming reconstruction of equilibrium, so that the method requires less computational time. The system evaluates q profile within every 10ms, which is much faster than current relaxation time, typically order of 1s. Safety factor profile by the real-time calculation agreed well with that by equilibrium reconstruction with MSE. From temporal evolution of q (or current) profile, we evaluate CD location in real-time, too. The control system controls rhoCD through $$N_{rm //}$$ (or directly dphi) in such a way to minimize difference between the real-time evaluated q profile and its reference profile. The real-time control system was applied to positive shear plasmas ($$q(0)sim 1$$), having plasma current of 0.6MA, toroidal field of 2.3T, and electron density of $$0.5times 10^{19}{rm m}^{-3}$$. In order to keep good coupling of LH waves to the plasma, gap between the launcher and the plasma surface was controlled to about 0.1m. The reference q profile was set to q(0)=1.3. The real-time q profile approached to the reference after application of real-time control; the controlled q profile was sustained for 3s, which was limited by injected LH power. RF experiments in JT-60U, such as stabilization of neo-classical tearing modes, plasma startup experiments, etc., are also presented.

Journal Articles

A New GUI system for profile control of plasma internal quantities in JT-60

Sueoka, Michiharu; Hosoyama, Hiroki*; Suzuki, Takahiro; Yonekawa, Izuru; Kurihara, Kenichi

Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03

no abstracts in English

Journal Articles

Steady state high $$beta_{rm N}$$ discharges and real-time control of current profile in JT-60U

Suzuki, Takahiro; Isayama, Akihiko; Sakamoto, Yoshiteru; Ide, Shunsuke; Fujita, Takaaki; Takenaga, Hidenobu; Luce, T. C.*; Wade, M. R.*; Oikawa, Toshihiro; Naito, Osamu; et al.

Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11

no abstracts in English

Journal Articles

Development of a new real-time plasma current profile control system for JT-60

Hosoyama, Hiroki*; Sueoka, Michiharu; Suzuki, Takahiro

KEK Proceedings 2003-16 (CD-ROM), 4 Pages, 2004/02

no abstracts in English

Journal Articles

Lessons learned from operation of the JT-60U plasma shape real-time visualization system

Hosoyama, Hiroki*; Sueoka, Michiharu; Kawamata, Yoichi

Heisei-14-Nendo Tokyo Daigaku Sogo Gijutsu Kenkyukai Gijutsu Hokokushu, p.359 - 361, 2003/03

no abstracts in English

Oral presentation

A New method of current profile reconstruction based on the exact solution of fredholm integral equation of the first kind

Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hosoyama, Hiroki; Suzuki, Takahiro; Fujita, Takaaki; Takenaga, Hidenobu; Ide, Shunsuke; Kamada, Yutaka

no journal, , 

no abstracts in English

15 (Records 1-15 displayed on this page)
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