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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:1 Percentile:93.32(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

Inter-code comparison benchmark between DINA and TSC for ITER disruption modelling

Miyamoto, Seiji*; Isayama, Akihiko; Bandyopadhyay, I.*; Jardin, S. C.*; Khayrutdinov, R. R.*; Lukash, V.*; Kusama, Yoshinori; Sugihara, Masayoshi*

Nuclear Fusion, 54(8), p.083002_1 - 083002_19, 2014/08

 Times Cited Count:23 Percentile:15.76(Physics, Fluids & Plasmas)

Two well-established simulation codes, DINA and TSC, are compared with each other using benchmark scenarios in order to validate the ITER 2D disruption modelling by those codes. Although the simulation models employed in those two codes ought to be equivalent in the resistive time scale, it has long been unanswered whether the one of the two codes is really able to reproduce the other result correctly, since a large number of code-wise differences render the comparison task exceedingly complicated. In this paper, it is demonstrated that after simulations are set up accounting for the model differences, in general, a good agreement is attained on a notable level, corroborating the correctness of the code results. When the halo current generation and its poloidal path in the first wall are included, however, the situation is more complicated. Because of the surface averaged treatment of the magnetic field (current density) diffusion equation, DINA can only approximately handle the poloidal electric currents in the first wall that cross field lines. Validation is carried out for DINA simulations of halo current generation by comparing with TSC simulations, where the treatment of halo current dynamics is more justifiable. The particularity of each code is depicted and the consequence in ITER disruption prediction is discussed.

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:100(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

Development of divertor IR thermography for ITER

Takeuchi, Masaki; Sugie, Tatsuo; Ogawa, Hiroaki; Ishikawa, Masao; Shimada, Takahiko; Kusama, Yoshinori

Plasma and Fusion Research (Internet), 8(Sp.1), p.2402147_1 - 2402147_5, 2013/11

Divertor IR Thermography is one of the diagnostics which Japan is in charge of development in ITER project. The conceptual design has been performed so far, and the progress is reported here. By reducing the size of mirrors, and making the optical path a labyrinthine structure, the design of a new optics that fills requirements of both spatial resolution and neutron shielding has been advanced. To achieve the required measurement accuracy, the detected signal and the noises such as bremsstrahlung light, detector noise and thermal noise of optical components were evaluated. Higher photons than the bremsstrahlung light are obtained, excluding the low temperature range. The simulation calculation of reflection from wall was started. Detailed method of data processing of deriving the profiles of surface temperature in the divertor plates from the observed signals and in-situ calibration strategies of the optical system are important issues and will be discussed.

Journal Articles

Neutronic analysis for ${it in situ}$ calibration of ITER in-vessel neutron flux monitor with microfission chamber

Ishikawa, Masao; Kondoh, Takashi; Kusama, Yoshinori; Bertalot, L.*

Fusion Engineering and Design, 88(6-8), p.1377 - 1381, 2013/10

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Neutronic analysis is performed for ${it in situ}$ calibration of the in-vessel neutron flux monitor in ITER, the Microfission Chamber (MFC). The transfer system of a neutron generator, which consists of two toroidal rings and a neutron generator holder, has been designed and its effect on the detection efficiency of the MFC is estimated through neutronic analysis with MCNP. The result indicates that the designed transfer system is unaffected for the detection efficiency of the MFC. ${it In situ}$ calibrations for the point by point method and the rotation method are simulated and compared through neutronic analysis. It is found that the rotation method is appropriate for full calibration because this method has the advantage that the calibration time can be shortened and all neutron flux monitors can be calibrated simultaneously.

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:78.12(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:73.69(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Simulation of VDE under intervention of vertical stability control and vertical electromagnetic force on the ITER vacuum vessel

Miyamoto, Seiji; Sugihara, Masayoshi*; Shinya, Kichiro*; Nakamura, Yukiharu*; Toshimitsu, Shinichi*; Lukash, V. E.*; Khayrutdinov, R. R.*; Sugie, Tatsuo; Kusama, Yoshinori; Yoshino, Ryuji*

Fusion Engineering and Design, 87(11), p.1816 - 1827, 2012/11

 Times Cited Count:11 Percentile:28.24(Nuclear Science & Technology)

Journal Articles

Development of a YAG laser system for the edge Thomson scattering system in ITER

Hatae, Takaki; Yatsuka, Eiichi; Hayashi, Toshimitsu; Yoshida, Hidetsugu*; Ono, Takehiro; Kusama, Yoshinori

Review of Scientific Instruments, 83(10), p.10E344_1 - 10E344_3, 2012/10

 Times Cited Count:10 Percentile:48.68(Instruments & Instrumentation)

A prototype YAG laser system for the edge Thomson scattering system in ITER has been newly developed. Performance of the laser amplifier was improved by using flow tubes made of samarium-doped glass; the small signal gain reached 20 at its maximum. As a result, an output energy of 7.66 J at 100 Hz was successfully achieved, and the performance exceeded the target performance (5 J, 100 Hz).

Journal Articles

Report on ITPA meetings, 37

Hayashi, Nobuhiko; Ide, Shunsuke; Suzuki, Takahiro; Itami, Kiyoshi; Kawano, Yasunori; Sasao, Mamiko*; Kusama, Yoshinori

Purazuma, Kaku Yugo Gakkai-Shi, 88(7), p.392 - 393, 2012/07

no abstracts in English

Journal Articles

Polychromator for the edge Thomson scattering system in ITER

Yatsuka, Eiichi; Hatae, Takaki; Fujie, Daijiro*; Kurokawa, Atsuo*; Kusama, Yoshinori

Review of Scientific Instruments, 83(10), p.10E328_1 - 10E328_3, 2012/07

 Times Cited Count:2 Percentile:85.12(Instruments & Instrumentation)

On the edge Thomson scattering (TS) system in ITER, the filter polychromator is used for dispersing the scattered radiation. Since the signal in TS system is very small, it is crucial to reduce the signal loss from the collection optics to the spectrometer. A band of wavelength in the signal is extracted by an interference filter, and the remaining part is reflected at the interference filter. On the conventional polychromator, a number of reflections are necessary for extracting all wavelength bands. We proposed a new type of polychromator. On the new polychromator, both transmitted and reflected signal from an interference filter are dispersed into transmitted and reflected parts again. It enables to reduce the number of reflection at the interference filters. We showed it is possible to apply in the edge TS system in ITER by setting the injection angle of signal light into the interference filters to be approximately less than 10 degrees.

Journal Articles

Highly accurate approximate solutions of the stokes equation for high electron density and long laser-wavelength

Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

Plasma Physics and Controlled Fusion, 54(5), p.055005_1 - 055005_7, 2012/05

 Times Cited Count:7 Percentile:63.87(Physics, Fluids & Plasmas)

JAEA Reports

Bi-directional reflectance distribution function of a tungsten block for ITER divertor

Iwamae, Atsushi*; Ogawa, Hiroaki; Sugie, Tatsuo; Kusama, Yoshinori

JAEA-Research 2011-045, 11 Pages, 2012/02

JAEA-Research-2011-045.pdf:2.36MB

In order to investigate reflection properties on plasma-facing material in ITER, the bi-directional reflectance distribution function (BRDF) of a tungsten block sample has been measured. On the machining surface of the block, one-directional machining lines are engraved. Two laser diodes $$lambda$$652 nm and $$lambda$$473 nm were used to simulate H$$_{alpha}$$ and H$$_{beta}$$ emissions, respectively. The reflected light is affected by the machining surface. The reflected light traces a line when the incident light is injected in the perpendicular direction to the engraved line. On the other hand the reflected light traces an arc shape when the incident light is injected in the parallel direction to the engraved lines. Ray tracing simulation qualitatively explains the experimental results.

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:27 Percentile:17.34(Physics, Fluids & Plasmas)

Journal Articles

Principles for local measurement of the anisotropic electron temperature of plasma using incoherent Thomson scattering

Yatsuka, Eiichi; Hatae, Takaki; Kusama, Yoshinori

Nuclear Fusion, 51(12), p.123004_1 - 123004_4, 2011/12

 Times Cited Count:5 Percentile:72.32(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

A New approach of equilibrium reconstruction for ITER

Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

Nuclear Fusion, 51(11), p.113022_1 - 113022_8, 2011/11

 Times Cited Count:21 Percentile:27.21(Physics, Fluids & Plasmas)

We have developed the new method for identifying the $$q$$-profile from data, whose accuracy is determined in ITER, in order to assess the necessary measurement accuracy of the poloidal polarimeter. We have adopted the finite element method to calculate the ideal MHD equilibrium. Assuming that all measurement data has no error, we have shown the Importance of using the measurement data of the electron temperature, $$T_e$$, and the ellipticity angle, $$epsilon$$, of the polarization state in the inductive operation scenario II (S2), and the non-inductive operation scenario IV (S4). $$T_e$$ is used to calculate the relativistic effect on the polarization state. When the relativistic effect has not been included in the $$q$$-profile identification, the error of $$q$$-profile identification has exceeded 7.7 ${%}$ and 15 ${%}$ in S2 and S4, respectively. $$epsilon$$ is mainly related to the Cotton-Mouton effect, which is an obstacle in measurement of a pure Faraday effect. Taking into account $$epsilon$$ reduced the error of $$q$$-profile identification by 0.5 ${%}$. Finally, we have assessed the necessary accuracy of the orientation angle, $$Deltatheta$$, and the ellipticity angle, $$Deltaepsilon$$. The polarimetric measurements with accuracy of $$(Deltatheta, Deltaepsilon)=(0.5^circ, 3^circ)$$ have satisfied the measurement requirement for the $$q$$-profile identification ($$pm5$$ ${%}$) in case of that viewing chords are via both equatorial and upper ports.

Journal Articles

Electromagnetic studies of the ITER generic upper port plug

Sato, Kazuyoshi; Yaguchi, Eiji; Pitcher, C. S.*; Walker, C.*; Encheva, A.*; Kawano, Yasunori; Kusama, Yoshinori

Fusion Engineering and Design, 86(6-8), p.1264 - 1267, 2011/10

 Times Cited Count:2 Percentile:78.31(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Neutronic analysis of the ITER poloidal polarimeter

Ishikawa, Masao; Kawano, Yasunori; Imazawa, Ryota; Sato, Satoshi; Vayakis, G.*; Bertalot, L.*; Yatsuka, Eiichi; Hatae, Takaki; Kondoh, Takashi; Kusama, Yoshinori

Fusion Engineering and Design, 86(6-8), p.1286 - 1289, 2011/10

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

The nuclear heating rates of the optical mirrors of the poloidal polarimeter installed in the equatorial port plug of ITER are calculated. Since the system cannot have a sufficiently labyrinthine structure and the second mirrors are located nearly as close to the plasma as the first mirrors due to limited space, the nuclear heating rate of the second mirrors is as high as that of the first mirrors. However, it is possible to reduce the nuclear heating rates of the mirrors if the blanket shield module provides a sufficient degree of neutron shielding.

348 (Records 1-20 displayed on this page)