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Katsumi, Toshiyuki; Thwe Thwe, A.; Kadowaki, Satoshi
Journal of Visualization, 25(5), p.1075 - 1083, 2022/10
Times Cited Count：1 Percentile：20.8(Computer Science, Interdisciplinary Applications)Lean combustion and inert-gas addition are useful to control the burning velocity of hydrogen premixed flames, and it is well known that the cellular structure forms on the front of lean hydrogen flames owing to intrinsic instability. However, the influences of inert-gas addition on the instability phenomena of lean hydrogen premixed flames are not understood fully, and then it is needed to be investigated the flame instability experimentally. In the experiments, the cellular structure and fluctuation of H
/O/inert gases (Ar, N,CO) premixed flames on a flat burner were obtained using direct observation, laser diagnostics and light emission intensity to elucidate the characteristics of instability phenomena. As the results, the correlation of inert-gas addition, equivalence ratio and total flow rate with the characteristics of cellular flames was revealed, and the influences of these parameters on flame instability were discussed.
Tominaga, Masahide*; Nagayasu, Yukari*; Sasaki, Motoharu*; Furuta, Takuya; Hayashi, Hiroaki*; Oita, Masataka*; Nishiyama, Yuichi*; Haga, Akihiro*
Radiological Physics and Technology, 14(4), p.381 - 389, 2021/12
Due to recent advance of diagnostic radiology, the increase of diagnostic radiation exposure to patient becomes problem. Diagnostic Reference Levels has been released to optimized the radiation exposure to patients in Japan recently. The evaluation of entrance surface dose (ESD) is recommended to assess the dose level for general X-ray examination. The ESD can be easily evaluated by multiplying the backscatter factor of the patient body on the free-in-air air kerma. The air kerma free-in-air value used to estimate ESD may contain X-rays scattered from obstacles located at the time of measurement, which may induce non-minor error in assessments. We therefore studied the influence of scattered X-rays on air kerma measurement under various environments (distances, field sizes, and materials). It was found that the dependence on the X-ray energy and field size was different for different materials. The X-ray contamination can be ignored for all the materials when the distance to the scatterer exceeds 35 cm.
Arikawa, Yasunobu*; Ikeda, Yujiro; Shimizu, Hirohiko*; Hanayama, Ryohei*; Kondo, Yasuharu*; Kurosawa, Shunsuke*
Reza Kenkyu, 46(11), p.634 - 640, 2018/11
Compact neutron sources have been used as various diagnostics such as a neutron diffraction, neutron resonant analysis, and neutron radiography. The developments of the neutron detectors are essential for all of these applications, while the techniques are strongly dependent on the neutron energy and the aim of the measurement. This paper reviews neutron detection techniques pertinent to promote compact neutron source uses. Along with general neutron detection systems with conventional counters for slow neutrons, we have highlighted detectors for high energy neutrons with high time resolution and high sensitivity which could be applied in a laser-driven compact neutron source.
Faenov, A.*; Matsubayashi, Masahito; Pikuz, T.*; Fukuda, Yuji; Kando, Masaki; Yasuda, Ryo; Iikura, Hiroshi; Nojima, Takehiro; Sakai, Takuro; Shiozawa, Masahiro*; et al.
High Power Laser Science and Engineering, 3, p.e27_1 - e27_9, 2015/10
Times Cited Count：10 Percentile：49.69(Optics)Sugie, Tatsuo
Purazuma Shindan No Kiso To Oyo, p.116 - 131, 2006/03
Radiation from the plasma degrades the performance of energy confinement. In addition, the efficiency of fusion reaction will be decreased by the fuel dilution due to the impurity ions in the plasma. Therefore, the impurity control (generation, reduction of the contamination, exhaust) becomes an important research subject. Spectroscopic diagnostics is the one of the most important methods to study such subjects. On the other hand, it is also utilized for the measurements of plasma parameters such as ion temperature, plasma current distribution etc. In this section, the radiation behavior and the spectroscopic diagnostics of high temperature plasma are described.
Kasai, Satoshi*; Kamiya, Kensaku; Shinohara, Koji; Kawashima, Hisato; Ogawa, Hiroaki; Uehara, Kazuya; Miura, Yukitoshi; Okano, Fuminori; Suzuki, Sadaaki; Hoshino, Katsumichi; et al.
Fusion Science and Technology, 49(2), p.225 - 240, 2006/02
Times Cited Count：3 Percentile：24.11(Nuclear Science & Technology)The diagnostic system of JFT-2M has consisted of about 30 individual diagnostic instruments,which were used to study the plasma production, control, equilibrium, stability, confinement, plasma heating by NBI and/or RF (LH, ICRF, ECH) and current drive by RF. In these instruments, the motional Stark effect (MSE) polarimeter, charge exchanged recombination spectroscopy (CXRS), heavy-ion beam probe (HIBP), time of flight (TOF) neutral particle analyzer, etc. have contributed to make clear the improved mechanism of confinement such as H-mode and High Recycling Steady (HRS) H-mode, and to search the operational region of these modes.The infrared TV camera system and lost ion probe have played a very important role to investigate the heat load onto the walls due to ripple loss particles and escaping ions from core plasma, respectively.
Nishitani, Takeo; Osakabe, Masaki*; Shinohara, Koji; Ishikawa, Masao
Purazuma, Kaku Yugo Gakkai-Shi, 80(10), p.860 - 869, 2004/10
no abstracts in English
Kondoh, Takashi; Costley, A. E.*; Sugie, Tatsuo; Kawano, Yasunori; Malaquias, A.*; Walker, C. I.*
Review of Scientific Instruments, 75(10), p.3420 - 3422, 2004/10
Times Cited Count：23 Percentile：72.22(Instruments & Instrumentation)In order to measure the line average electron density on ITER, a CO laser interferometer/polarimeter system is being developed. The design of the interferometer/polarimeter is improved from the previous design, which uses CO and CO laser, on the basis of experience gained with a dual CO system on JT-60U in which good reliability was confirmed for both interferometry and polarimetry operation. The performance of the dual CO laser meets requirements for ITER (accuracy; 1%, time resolution; 1 ms).
Nishitani, Takeo; Vayakis, G.*; Yamauchi, Michinori*; Sugie, Tatsuo; Kondoh, Takashi; Shikama, Tatsuo*; Ishitsuka, Etsuo; Kawashima, Hisato
Journal of Nuclear Materials, 329-333(Part2), p.1461 - 1465, 2004/08
Times Cited Count：16 Percentile：70(Materials Science, Multidisciplinary)no abstracts in English
Takatsu, Hideyuki; Sato, Kazuyoshi; Hamada, Kazuya; Nakahira, Masataka; Suzuki, Satoshi; Nakajima, Hideo; Kuroda, Toshimasa*; Nishitani, Takeo; Shikama, Tatsuo*; Shu, Wataru
Journal of Nuclear Materials, 329-333(1), p.178 - 182, 2004/08
Times Cited Count：2 Percentile：17.18(Materials Science, Multidisciplinary)This paper presents an overview on ITER-supporting materials research and development activities and major achievements in Japan during the period from the Co-ordinated Technical Activities to date. In view of the completed engineering design of ITER during the Engineering Design Activities period, research and development efforts since then have been focused: those for reduction of component fabrication cost; those in support of domestic preparations of a structural technical code for construction; those necessary for operation, and been extended to component-level testing rather than pure material testing. They cover materials Research and Development for in-vessel components, vacuum vessel, cryogenic steels of superconducting mgnet and diagnostics components. Major achievements in each research and development area are highlighted and their impact or implication to the design, construction and operation of ITER is presented.
Mironov, M. I.*; Khudoleev, A. V.*; Kusama, Yoshinori
Plasma Physics Reports, 30(2), p.164 - 168, 2004/02
Times Cited Count：0 Percentile：0.02(Physics, Fluids & Plasmas)High-energy charge-exchange diagnostics can determine the distribution function of fast atoms produced via the neutralization of hydrogen ions by hydrogen-like impurity ions. Deriving the distribution function requires to know the composition and spatial distribution of the target ions in a plasma. A charge-exchange target forms as a result of the interaction between impurity nuclei and beam atoms. Depending on the arrangement of heating beams with respect to the diagnostics, it is necessary to calculate their trajectories. A model which takes into account elementary processes resulting in the ionization equilibrium of the ions of impurities in a specific tokamak configuration is proposed. The model is applied to the JT-60U plasma. Mechanisms for the formation of charge-exchange atomic flows are considered. The relative contributions of different heating injectors to the charge-exchange flow are estimated. Based on the calculated results, a method is proposed for local measurements of the ion distribution function with a stationary analyzer.
JT-60 Team
JAERI-Review 2003-029, 197 Pages, 2003/11
JAERI-Review-2003-029.pdf:13.06MB
no abstracts in English
Sugie, Tatsuo; Costley, A. E.*; Malaquias, A.*; Walker, C.*
Purazuma, Kaku Yugo Gakkai-Shi, 79(10), p.1051 - 1061, 2003/10
The main regions - the core, the edge, the scrape-off layer, and the divertor - will be probed by an extensive array of spectroscopic instrumentation covering the visible to X-ray wavelength range. Plasma parameters will be determined including impurity species/density/input-flux, ion temperature, He density, fueling ratio, plasma rotation, effective ionic charge and safety factor q. The measurements will be used for plasma control and in studies to understand and improve the performance of ITER. A diagnostic neutral beam (~100 keV) will be installed for Charge Exchange Recombination Spectroscopy. Motional Stark Effect measurements (for q profile) will be made using the heating beam (1 MeV). Diagnostic components, such as mirrors, windows, and optical fibers etc, mounted close to the plasma will experience higher levels of radiation due to neutron, gamma ray and particle irradiations than in present devices. Potentially their performance characteristics can be degraded and so the materials of the components have to be carefully selected and mitigating methods adopted where possible.
Sugie, Tatsuo; Costley, A. E.*; Malaquias, A.*; Medvedev, A.*; Walker, C.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07
The main functions of the Divertor Impurity Monitor are to measure the parameters of impurities and isotopes of hydrogen in the divertor plasmas by using spectroscopic techniques in the wavelength range of 200-1000 nm. This system will have three different types of spectrometers; a) Visible survey spectrometers for impurity species monitoring. b) Filter spectrometers for two-dimensional measurements of particle influxes. c) High dispersion spectrometers for measuring the ion temperature and the particle energy distribution. The divertor region will be observed from the divertor-, the equatorial- and the upper-port. Optical components, such as mirrors, windows etc, mounted close to the plasma will experience higher levels of radiation due to neutron, gamma ray and/or particle irradiations than in present devices. Therefore, the materials of the components have to be carefully selected and mitigating methods adopted where possible. In addition, in-situ and remote calibration methods for diagnostic systems, which will be installed in the strong radiation field, are absolutely essential.
Nishitani, Takeo; Ebisawa, Katsuyuki*; Kasai, Satoshi; Walker, C.*
Review of Scientific Instruments, 74(3), p.1735 - 1738, 2003/03
Times Cited Count：14 Percentile：58.66(Instruments & Instrumentation)no abstracts in English
laser for ion energy spectrum measurements in JT-60UKondoh, Takashi; Miura, Yukitoshi; Lee, S.*; Richards, R. K.*; Hutchinson, D. P.*; Bennett, C. A.*
Review of Scientific Instruments, 74(3), p.1642 - 1645, 2003/03
Times Cited Count：20 Percentile：68.22(Instruments & Instrumentation)Measurements of energy spectrum and density profile of confined alpha-particles are required for ITER. Several methods have been proposed, however, a measurement technique hasn't been established yet. A collective Thomson scattering (CTS) system based on a pulsed CO laser is being developed to demonstrate feasibility of alpha-particle diagnostics for ITER. The pulse laser (15J, 1
m, 0.6 m) and a wide band (~ 8GHz) heterodyne receiver with a quantum-well infrared photodetector (QWIP) have been developed and installed in the JT-60U tokamak. Stray light is reduced by a notch filter with hot CO gas. Heterodyne receiver is absolutely calibrated using large area blackbody radiation source. Scattered signal from JT-60U plasma has not detected because of electrical noise originated from discharge of the pulsed laser and stray signal caused by impurity of the spectrum of the pulsed laser.
Peterson, B. J.*; Ashikawa, Naoko*; Konoshima, Shigeru; Ingesson, L. C.*; Walker, C. I.*
Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/00
Research and development of imaging bolometers has progressed from the Segmented Mask IR Imaging Bolometer to the IR Imaging Video Bolometer (IRVB). Meanwhile tests of conventional resistive bolometers have shown their weakness to the high neutron flux. In this paper we compare the IRVBs currently installed in the Large Helical Device with a conceptual design for the JT-60U tokamak and a feasibility study for the International Thermonuclear Experimental Reactor. Comparisons are made with conventional resistive bolometers in terms of sensitivity, spatial and time resolution, port access requirements, steady-state operation, long term durability and shielding of stray ECH power.
Nishitani, Takeo; Sugie, Tatsuo; Kasai, Satoshi; Kaneko, Junichi*; Yamamoto, Shin
Journal of Nuclear Materials, 307-311(Part2), p.1264 - 1267, 2002/12
Times Cited Count：23 Percentile：79.51(Materials Science, Multidisciplinary)no abstracts in English
Bruskin, L. G.; Mase, Atsushi*; Oyama, Naoyuki; Miura, Yukitoshi
Plasma Physics and Controlled Fusion, 44(11), p.2305 - 2325, 2002/11
Times Cited Count：17 Percentile：48.88(Physics, Fluids & Plasmas)The results of analytical solution of time-dependent 2D full-wave equation are presented here for the case of fluctuation reflectometry. We consider a family of plasma density profiles with cylindrical symmetry, which allow for an integration of the microwave scattering equation. Based on the results of analytical modeling, Doppler reflectometry as a method of plasma velocity measurements is investigated. It is shown that the accuracy of Doppler shift measurements is sensitive to the spectral content of the broadband turbulence, as well as to the curvature of the plasma cut-off layer. Addressing the problem of fluctuation amplitude measurements, it is suggested that a power-related parameter of the microwave signal, called fluctuation index, is suitable to quantify the plasma turbulence level provided that the fluctuation spectrum is a priori estimated.
Sugie, Tatsuo; Hatae, Takaki; Koide, Yoshihiko; Fujita, Takaaki; Kusama, Yoshinori; Nishitani, Takeo; Isayama, Akihiko; Sato, Masayasu; Shinohara, Koji; Asakura, Nobuyuki; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.482 - 511, 2002/09
Times Cited Count：6 Percentile：3.03(Nuclear Science & Technology)The diagnostic system of JT-60U (JT-60upgrade) is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters have been improved, so that the internal structure of plasmas has been explored. The understanding of plasma confinement has been enhanced by density and temperature fluctuation measurements using a mm-wave reflectometer and electron cyclotron emission measurements respectively. In addition, the real-time control experiments of electron density, neutron yield, radiated power and electron temperature gradient have been carried out successfully by corresponding diagnostic devices. These measurements and the real time control contribute to improving plasma performance. Diagnostic devices for next generation fusion devices such as a CO2 laser interferometer/polarimeter and a CO2 laser collective Thomson scattering system have been developed.
