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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
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
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
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
Yatsuka, Eiichi; Bassan, M.*; Hatae, Takaki; Ishikawa, Masao; Shimada, Takahiko; Vayakis, G.*; Walsh, M.*; Scannell, R.*; Huxford, R.*; Bilkova, P.*; et al.
Journal of Instrumentation (Internet), 8(12), p.C12001_1 - C12001_10, 2013/12
Times Cited Count：12 Percentile：49.93(Instruments & Instrumentation)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.
calibration of ITER in-vessel neutron flux monitor with microfission chamberIshikawa, Masao; Kondoh, Takashi; Kusama, Yoshinori; Bertalot, L.*
Fusion Engineering and Design, 88(6-8), p.1377 - 1381, 2013/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Neutronic analysis is performed for 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. 
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.
Sasao, Mamiko*; Ishikawa, Masao; Yuan, G.*; Patel, K.*; Jakhar, S.*; Kashchuk, Y.*; Bertalot, L.*
Plasma and Fusion Research (Internet), 8(Sp.1), p.2402127_1 - 2402127_3, 2013/09
Fusion power output of ITER is measured by a group of neutron flux monitors combined with a neutron activation system and neutron profile monitors. These systems should be absolutely calibrated by use of DD/DT generators moving inside the ITER vacuum vessel (in-situ calibration). Each neutron monitor has a limited measurement range of emission rate, but the ranges are connected by cross-calibration using the ITER plasma with at least one decade overlapping. The over all dynamic range covered by the group of neutron flux monitors is 10
n/sec to 10
n/sec. Effects of vertical/radial movement of plasma on the measurement accuracy were reviewed. It was found that cross-calibration using specially planned jog shots, and a vertical neutron camera is important to minimize the inaccuracy caused by the plasma movement.
Bierwage, A.; Aiba, Nobuyuki; Shinohara, Koji; Todo, Yasushi*; Deng, W.*; Ishikawa, Masao; Matsunaga, Go; Yagi, Masatoshi
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2012/10
Bierwage, A.; Aiba, Nobuyuki; Todo, Yasushi*; Deng, W.*; Ishikawa, Masao; Matsunaga, Go; Shinohara, Koji; Yagi, Masatoshi
Plasma and Fusion Research (Internet), 7(Sp.1), p.2403081_1 - 2403081_4, 2012/07
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：1 Percentile：10.73(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.
Vayakis, G.*; Bertalot, L.*; Encheva, A.*; Walker, C.*; Brichard, B.*; Cheon, M. S.*; Chitarin, G.*; Hodgson, E.*; Ingesson, C.*; Ishikawa, Masao; et al.
Journal of Nuclear Materials, 417(1-3), p.780 - 786, 2011/10
Times Cited Count：27 Percentile：87.94(Materials Science, Multidisciplinary)Bierwage, A.; Todo, Yasushi*; Aiba, Nobuyuki; Shinohara, Koji; Ishikawa, Masao; Yagi, Masatoshi
Plasma and Fusion Research (Internet), 6, p.2403109_1 - 2403109_5, 2011/08
Ishikawa, Masao; Kondoh, Takashi; Nishitani, Takeo; Kusama, Yoshinori
Fusion Engineering and Design, 86(4-5), p.417 - 420, 2011/06
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)A Microfission Chamber (MFC) provides time-resolved measurements of global neutron source strength in ITER. Measurements of the neutron source strength could be affected by cooling water in branch pipes installed near the MFC. The effect of the branch pipes upon the MFC is assessed through neutron transport calculation. Results indicate a significant increase in the MFC response rate due to the branch pipe. The increase in the MFC response is caused by the slowing down of the neutrons due to the cooling water in the branch pipes. One possible solution to reduce the effect is to cover the MFC with a material that absorbs thermal neutrons such as cadmium. The ways in which the absorbent material may affect MFC response is analyzed through neutron transport calculation. Results indicate that the increase in the MFC response can be reduced to 
10% through cadmium coating.
Ishikawa, Masao; Kondoh, Takashi; Okawa, Kiyofumi*; Fujita, Kyoichi*; Yamauchi, Michinori*; Hayakawa, Atsuro*; Nishitani, Takeo; Kusama, Yoshinori
Review of Scientific Instruments, 81(10), p.10D308_1 - 10D308_3, 2010/10
Times Cited Count：2 Percentile：13.26(Instruments & Instrumentation)Microfission chambers (MFCs) will provide total neutron source strength in ITER. The MFC is a pencil-sized gas counter containing the fissile material, 
U. The MFCs will be installed behind blanket modules in the vacuum vessel (VV). Double coaxial mineral insulated (MI) cables will carry signals from the MFCs to the upper port. Though the MI cables will be installed at a factory of the vacuum vessel or ITER assembly hall, detectors with U will be installed to the vacuum vessel at the tokamak pit. Then, the MI cable should be connected in the vacuum vessel. In this work, the connection of the MI cable with the MFC was conceptually designed. The MI cable should be also installed with small curvature radius (R) of 100 
200 mm to avoid the VV structure and other diagnostics. So, the vending test of the MI cable was conducted. As a result, damages leak, electrical disconnection and the change in insulation resistance have not been observed at R = 100 mm.
discrimination on neutron emission profile measurement on JT-60UIshii, Keiichi*; Shinohara, Koji; Ishikawa, Masao; Baba, Mamoru*; Isobe, Mitsutaka*; Okamoto, Atsushi*; Kitajima, Sumio*; Sasao, Mamiko*
Review of Scientific Instruments, 81(10), p.10D334_1 - 10D334_3, 2010/10
Times Cited Count：6 Percentile：30.96(Instruments & Instrumentation)Sasao, Mamiko*; Bertalot, L.*; Ishikawa, Masao; Popovichev, S.*
Review of Scientific Instruments, 81(10), p.10D329_1 - 10D329_3, 2010/10
Times Cited Count：16 Percentile：55.65(Instruments & Instrumentation)Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement sub-system, cross calibration among them, and in-situ calibration, are needed. Neutron transport calculations show that a suitable calibration source is a DT/DD neutron generator of source strength higher than 10
n/s for DT and 10
n/s for DD. It will take 8 weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.
Ishikawa, Masao; Kondoh, Takashi; Nishitani, Takeo; Kawano, Yasunori; Kusama, Yoshinori
Journal of Plasma and Fusion Research SERIES, Vol.9, p.43 - 47, 2010/08
Neutron transport analysis is very important for design and optimization of diagnostics in ITER. Especially, in-vessel diagnostics are exposed to strong neutron and radiation and then it could lead to damage and temperature increase due to nuclear heating of the components of those diagnostics. High dose rate due to strong radiation also makes those maintenances difficult. Therefore, evaluation of neutron/ flux, spectrum and nuclear heating at the location of the diagnostics with neutron transport analysis are essential to design a neutron radiation shield system and/or a cooling system. In this paper, results of neutron transport analysis applied to in-vessel components of the microfission chamber (MFC) and the poloidal polarimeter, which are developed by Japan Atomic Energy Agency, are presented.
Ishikawa, Masao; Kondoh, Takashi; Nishitani, Takeo; Kusama, Yoshinori
Journal of Plasma and Fusion Research SERIES, Vol.8, p.334 - 337, 2009/09
Microfission chambers (MFCs) are one of the most important diagnostics to measure total neutron source strength in ITER. The MFCs will be installed behind blanket modules upper outboard and lower outboard in the vacuum vessel. Double coaxial mineral insulated (MI) cables as signal cables are also installed form the MFCs to the upper port. It is very difficult to install the MI cables together with the MFC because of the security regulation. In this design work, a new type of MFC, which can be separable from the MI cable, has been designed. On the other hand, steaming neutrons along the gap between two blanket modules can affect the absolute measurement of total neutron source strength. The effects of streaming neutrons tat the installation position are investigated by a neutron Monte Carlo calculation using MCNP version 5 code. The result suggests that the effect of streaming neutrons should be taken into account if the MFCs are installed at the distance less than 20 cm from the gap.
Sato, Kazuyoshi; Omori, Junji; Kondoh, Takashi; Hatae, Takaki; Kajita, Shin*; Ishikawa, Masao; Neyatani, Yuzuru; Ebisawa, Katsuyuki*; Kusama, Yoshinori
Fusion Engineering and Design, 84(7-11), p.1713 - 1715, 2009/06
Times Cited Count：1 Percentile：10.22(Nuclear Science & Technology)Engineering analyses have been performed for the representative diagnostic upper port plug of ITER. Maintenance and integration design have been also carried out for the diagnostic components to be installed in the upper port plug. From the electromagnetic and structural analyses, it has come up an important problem to suppress the displacement of the upper port plug rather than to reduce the produced stress. Reducing the EM force will help to decrease the severity of potential displacement. Maximum displacement of the port plug decreases with increasing in the number of slits in a manner that the displacement would seem to be less than the design tolerance. A proposed low body roller and inner frame may enhance maintenance and integration. These studies and designs have established the design basis for the diagnostic upper port plug.
