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Journal Articles

ITPA (International Tokamak Physics Activity) meeting report, 53

Kawano, Yasunori; Akiyama, Tsuyoshi*; Ishikawa, Masao; Isobe, Mitsutaka*; Itami, Kiyoshi; Ejiri, Akira*; Peterson, B.*

Purazuma, Kaku Yugo Gakkai-Shi, 92(2), P. 145, 2016/02

no abstracts in English

Journal Articles

Development of real-time rotating waveplate Stokes polarimeter using multi-order retardation for ITER poloidal polarimeter

Imazawa, Ryota; Kawano, Yasunori; Ono, Takehiro; Itami, Kiyoshi

Review of Scientific Instruments, 87(1), p.013503_1 - 013503_7, 2016/01

AA2015-0219.pdf:1.34MB

 Times Cited Count:2 Percentile:14.5(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Development of instrumentation and control systems for the ITER diagnostic systems in JADA

Yamamoto, Tsuyoshi; Hashimoto, Yasunori*; Kitazawa, Sin-iti; Yatsuka, Eiichi; Hatae, Takaki; Sugie, Tatsuo; Ogawa, Hiroaki; Takeuchi, Masaki; Kawano, Yasunori; Itami, Kiyoshi

Fusion Engineering and Design, 96-97, p.1012 - 1016, 2015/10

 Times Cited Count:4 Percentile:40.75(Nuclear Science & Technology)

Japan Domestic Agency (JADA) is responsible for six diagnostic systems in the ITER project. We have successfully developed an instrumentation and control (I&C) system for the diagnostic systems. The I&C system manages internal operations for measurement such as health checks of sensors, configuration of measurement parameters, and consistency checks between measurement parameters. We developed a conversion tool to convert operational flowcharts to EPICS records. The sequencing management function coordinates the execution of operation steps by monitoring changes in the record values. It was designed so that the relationship between the records and steps is determined automatically according to the flowcharts as much as possible. We validated the performance of the I&C system for the thermocouple measurement system, and are continuing the development of even more complex I&C systems for other JADA diagnostic systems.

Journal Articles

ITPA (International Tokamak Physics Activity) meeting report, 50

Kawano, Yasunori; Akiyama, Tsuyoshi*; Ishikawa, Masao; Isobe, Mitsutaka*; Itami, Kiyoshi; Ejiri, Akira*; Peterson, B.*

Purazuma, Kaku Yugo Gakkai-Shi, 91(8), P. 565, 2015/08

no abstracts in English

Journal Articles

Meshless method for solving fixed boundary problem of plasma equilibrium

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

Journal of Computational Physics, 292, p.208 - 214, 2015/07

 Times Cited Count:5 Percentile:41.4(Computer Science, Interdisciplinary Applications)

no abstracts in English

Journal Articles

ITPA (International Tokamak Physics Activity) meeting report, 48

Kawano, Yasunori; Akiyama, Tsuyoshi*; Ishikawa, Masao; Isobe, Mitsutaka*; Itami, Kiyoshi; Ejiri, Akira*; Peterson, B. J.*

Purazuma, Kaku Yugo Gakkai-Shi, 91(1), P. 76, 2015/01

no abstracts in English

Journal Articles

Profile measurement of current density, electron density and electron temperature using laser polarimetry on burning plasma

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

Purazuma, Kaku Yugo Gakkai-Shi, 90(11), p.743 - 747, 2014/11

no abstracts in English

Journal Articles

Multi-parameter measurement using finite electron temperature effect on laser polarimetry for burning plasma reactor

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi

Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 6 Pages, 2014/10

no abstracts in English

Journal Articles

Magnification of a polarization angle with a Littrow layout brazed grating

Sasao, Hajime; Arakawa, Hiroyuki*; Kubo, Hirotaka; Kawano, Yasunori; Itami, Kiyoshi

Review of Scientific Instruments, 85(8), p.086106_1 - 086106_3, 2014/08

 Times Cited Count:2 Percentile:13.22(Instruments & Instrumentation)

Journal Articles

ITPA (International Tokamak Physics Activity) meeting report, 46

Kawano, Yasunori; Akiyama, Tsuyoshi*; Ishikawa, Masao; Isobe, Mitsutaka*; Itami, Kiyoshi; Ejiri, Akira*; Peterson, B.*

Purazuma, Kaku Yugo Gakkai-Shi, 90(7), P. 431, 2014/07

no abstracts in English

Journal Articles

Role of the electron temperature in the current decay during disruption in JT-60U

Shibata, Yoshihide; Isayama, Akihiko; Matsunaga, Go; Kawano, Yasunori; Miyamoto, Seiji*; Lukash, V.*; Khayrutdinov, R.*; JT-60 Team

Plasma and Fusion Research (Internet), 9(Sp.2), p.3402084_1 - 3402084_5, 2014/06

We performed the disruption simulation using DINA code to investigate the effect of the electron temperature $$T_{rm e}$$ on the plasma current decay after the initial phase of current quench (CQ). In this calculation, we used the measured $$T_{rm e}$$ profile during the initial phase of CQ. After the initial phase of CQ, we assumed that the $$T_{rm e}$$ profile does not change in time and used the value at the end of the initial phase of current quench because $$T_{rm e}$$ profile could not be measured after the initial phase of CQ. From the simulation results, it was found that the time evolution of plasma current calculated by DINA was similar to experimental one in this calculation. However, the time evolution of $$T_{rm e}$$profile in this calculation was different from the measured $$T_{rm e}$$ profile because Te after first mini-collapse rapidly decreased until the value below a measurement limit (less than 0.1 keV). Moreover, the time evolution of poloidal cross-section S calculated by DINA code was rapidly decreased although the experimental one was gradually decreased. The plasma current decay during the disruption is determined by various parameters, $$dL_{rm p}/dt$$, $$T_{rm e}$$ and S. It is necessary to evaluate the effect of $$T_{rm e}$$ profile on the plasma current decay after the initial phase of CQ by using various assumed $$T_{rm e}$$ model and DINA code.

Journal Articles

Development of the supervisory systems for the ITER diagnostic systems in JADA

Yamamoto, Tsuyoshi; Hashimoto, Yasunori*; Serizawa, Yasunori*; Inamoto, Shuji*; Sato, Kazuyoshi; Sugie, Tatsuo; Takeuchi, Masaki; Kawano, Yasunori

Fusion Engineering and Design, 89(5), p.532 - 535, 2014/05

 Times Cited Count:1 Percentile:10.7(Nuclear Science & Technology)

The diagnostic systems are essential for the plasma control and physics understandings. JAEA has proposed the new concept of supervisory system which manages operation sequences, current state and configuration parameters for the measurement based on our experiences in operating plasma diagnostic systems. We designed the supervisory system satisfying the requirements from both CODAC system and diagnostic systems. In our design, the tool which converts operational steps described as flowcharts into EPICS Records templates is introduced. This tool will ensure reduction of the system designers' efforts. We also designed the sequencing simulator that can submit transition commands internally instead of CODAC system for the calibration and commissioning. The mechanism which changes the limit values and consistency check algorithms in accordance with the conditions of the diagnostics system is also proposed.

Journal Articles

Progress of preparation for ITER divertor thermocouple in JADA

Kitazawa, Sin-iti; Yamamoto, Tsuyoshi; Kawano, Yasunori; Itami, Kiyoshi

Plasma and Fusion Research (Internet), 9(Sp.2), p.3405049_1 - 3405049_4, 2014/05

The Japan Domestic Agency (JADA) is scheduled to procure a divertor thermocouple (DTC) system for the divertor outer vertical targets in the ITER project. The DTC is a diagnostic device that will directly measure the surface temperature of the divertor, a plasma-facing component, and will be installed on the surface of the divertors which are in the scope of JADA procurement sharing. A thermocouple itself is a conventional device used for measuring temperature, however, for the DTC to be able to take highly reliable operation under the ultrahigh vacuum and high radiation field of the ITER environment. Therefore various advanced research and development is necessary. Development of the DTC control system, which is based on ITER standards, should also be performed since it is included within the scope of JADA procurement. In this presentation, we will show the current status of research & development on the DTC.

Journal Articles

The Effect of the electron temperature and current density profiles on the plasma current decay in JT-60U disruptions

Shibata, Yoshihide; Isayama, Akihiko; Miyamoto, Seiji*; Kawakami, Sho*; Watanabe, Kiyomasa*; Matsunaga, Go; Kawano, Yasunori; Lukash, V.*; Khayrutdinov, R.*; JT-60 Team

Plasma Physics and Controlled Fusion, 56(4), p.045008_1 - 045008_8, 2014/04

 Times Cited Count:2 Percentile:12.49(Physics, Fluids & Plasmas)

In JT-60U disruption, the plasma current decay during the initial phase of current quench has been calculated by a disruption simulation code (DINA) using the measured electron temperature $$T_{rm e}$$ profile. In the case of fast plasma current decay, $$T_{rm e}$$ has a peaked profile just after thermal quench and the $$T_{rm e}$$ profile doesn't change significantly during the initial phase of current quench. On the other hand, in the case of the slow plasma current decay, the $$T_{rm e}$$ profile is border just after the thermal quench, and the $$T_{rm e}$$ profile shrinks. The results of DINA simulation show that plasma internal inductance $$L_{rm i}$$ increases during the initial phase of current quench, while plasma external inductance $$L_{rm e}$$ does not change in time. The increase of $$L_{rm i}$$ is caused by current diffusion toward the core plasma due to the decrease of $$T_{rm e}$$ in intermediate and edge regions. It is suggested that an additional heating in the plasma periphery region has the effect of slowing down plasma current decay.

Journal Articles

ITPA meeting report, 43

Kawano, Yasunori; Itami, Kiyoshi; Kawahata, Kazuo*; Kusama, Yoshinori; Sasao, Mamiko*; Peterson, B.*; Mase, Atsushi*

Purazuma, Kaku Yugo Gakkai-Shi, 90(2), P. 164, 2014/02

no abstracts in English

Journal Articles

Linearity-independent method for a safety factor profile

Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi; Kusama, Yoshinori

Nuclear Fusion, 54(1), p.013012_1 - 013012_8, 2014/01

 Times Cited Count:0 Percentile:0.01(Physics, Fluids & Plasmas)

This paper proposes a new method to calculate a safety factor, $$q$$, profile from gridded data of a poloidal flux, $$Psi$$, efficiently and accurately. Difficulties of calculating $$q$$ are derived from a difficulty of specifying a contour line of $$Psi$$ and a singularity at a magnetic axis. In order to solve the first difficulty, the proposed method interpolates knots, which are located on a target $$Psi$$, by utilizing a normalized arc length and constraints expressed by a magnetic field. Regarding the second difficulty, the proposed method identifies $$q_0$$ by extrapolating $$q$$ profile around a magnetic axis with a constraint of $$mathrm{d}q/mathrm{d}rho=0$$ at the magnetic axis. Accuracy assessments of the proposed method are carried out by utilizing Solov'ev type equilibrium. The results show the validity and high performance of the proposed method.

Journal Articles

Effect of resistivity profile on current decay time of initial phase of current quench in neon-gas-puff inducing disruptions of JT-60U

Kawakami, Sho*; Shibata, Yoshihide; Watanabe, Kiyomasa*; Ono, Noriyasu*; Isayama, Akihiko; Takizuka, Tomonori*; Kawano, Yasunori; Okamoto, Masaaki*

Physics of Plasmas, 20(11), p.112507_1 - 112507_6, 2013/11

 Times Cited Count:2 Percentile:10.4(Physics, Fluids & Plasmas)

According to an early work on the behavior of the plasma current decay in the JT-60U disruptive discharges caused by the radiative collapse with a massive neon-gas-puff, the increase of the internal inductance mainly determined the current decay time of plasma current during the initial phase of current quench. To investigate what determines the increase of the internal inductance, we focus attention on the relationship between the electron temperature (or the resistivity) profile and the time evolution of the current density profile, and carry out numerical calculations. As a result, we find the reason of the increase of the internal inductance: The current density profile at the start of the current quench is broader than an expected current density profile in the steady state, which is determined by the temperature (or resistivity) profile. The current density profile evolves into peaked one and the internal inductance is increasing.

Journal Articles

ITPA meeting report, 41

Itami, Kiyoshi; Kawano, Yasunori; Kawahata, Kazuo*; Kusama, Yoshinori; Sasao, Mamiko*; Peterson, B.*; Mase, Atsushi*

Purazuma, Kaku Yugo Gakkai-Shi, 89(9), P. 638, 2013/09

no abstracts in English

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

Separation of finite electron temperature effect on plasma polarimetry

Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

Review of Scientific Instruments, 83(12), p.123507_1 - 123507_5, 2012/12

 Times Cited Count:4 Percentile:24.65(Instruments & Instrumentation)

no abstracts in English

213 (Records 1-20 displayed on this page)