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Kokusen, Shigeharu; Yoshida, Maiko; Tojo, Hiroshi
JAEA-Technology 2015-041, 26 Pages, 2016/02
Shutters will be installed in front of vacuum windows of some diagnostics in JT-60SA to avoid deposition of impurity onto the vacuum window during wall cleaning and plasma conditioning. Two types of shutter systems had been designed. One has a light shutter (0.5 kg) with rotary motion in vacuum. Another has a heavy shutter (3 kg) with vertical motion in vacuum. For the both types, malfunction due to increase of friction coefficients of the sliding parts in vacuum is concerned. In the present paper, Durability, abrasion and friction coefficient of the sliding parts has been investigated and the shutter designs have been validated. The light shutter with rotary motion successfully rotated required times (4000 times), and the design was validated. On the other hand, for the heavy shutter with vertical motion, the test could not be carried out due to the large friction of the sliding parts. This result suggests that we should change the material of the sliding parts to reduce the friction or change the design from the sliding structure to other ones such as a structure using pulleys and bearings. In the test of the heavy shutter with vertical motion, the friction coefficient increased from 1.3 to 4.5 in the vacuum chamber and from 0.4 to 2.5 in the air.
Fukumoto, Masakatsu; Miyata, Yoshiaki; Tojo, Hiroshi
Purazuma, Kaku Yugo Gakkai-Shi, 91(5), P. 371, 2015/05
"18th Plasma Seminar for young researches" (by Department of Advanced Plasma Research, Sector of Fusion Research and Development, Japan Atomic Energy Agency) was held in Naka Fusion Institute, March 3rd through 6th of 2015. The objective of this seminar is that the young researchers in charge of the future fusion research expand their cross-sectoral network. This seminar was entitled "Crystallization of technology of plasma measurement and control" and we invited the lectures not just for fusion plasma but for technology of plasma measurement and control to study the technology of measurement and control of different fields from their fields. There were 8 invited lectures and 17 public lectures and young researchers had an animated discussion.
Tojo, Hiroshi; Yamada, Ichihiro*; Yasuhara, Ryo*; Yatsuka, Eiichi; Funaba, Hisamichi*; Hatae, Takaki; Hayashi, Hiroshi*; Itami, Kiyoshi
Review of Scientific Instruments, 85(11), p.11D865_1 - 11D865_3, 2014/11
Times Cited Count:2 Percentile:11.31(Instruments & Instrumentation)Tojo, Hiroshi; Hatae, Takaki; Hamano, Takashi; Sakuma, Takeshi; Itami, Kiyoshi
Journal of Instrumentation (Internet), 8(12), p.C12025_1 - C12025_13, 2013/12
Times Cited Count:3 Percentile:17.27(Instruments & Instrumentation)Tojo, Hiroshi; Hatae, Takaki; Hamano, Takashi; Sakuma, Takeshi; Itami, Kiyoshi
Review of Scientific Instruments, 84(9), p.093506_1 - 093506_8, 2013/09
Times Cited Count:3 Percentile:17.27(Instruments & Instrumentation)Tojo, Hiroshi; Hatae, Takaki; Yatsuka, Eiichi; Itami, Kiyoshi
Review of Scientific Instruments, 83(10), p.10E346_1 - 10E346_3, 2012/10
Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)Tojo, Hiroshi; Hatae, Takaki; Itami, Kiyoshi
Journal of Instrumentation (Internet), 7(5), p.C05004_1 - C05004_11, 2012/05
Times Cited Count:10 Percentile:44.33(Instruments & Instrumentation)Tojo, Hiroshi; Ejiri, Akira*; Hiratsuka, Junichi*; Yamaguchi, Takashi*; Takase, Yuichi*; Itami, Kiyoshi; Hatae, Takaki
Journal of Instrumentation (Internet), 7(4), p.P04005_1 - P04005_11, 2012/04
Times Cited Count:3 Percentile:17.28(Instruments & Instrumentation)Tojo, Hiroshi; Ejiri, Akira*; Hiratsuka, Junichi*; Yamaguchi, Takashi*; Takase, Yuichi*; Itami, Kiyoshi; Hatae, Takaki
Review of Scientific Instruments, 83(2), p.023507_1 - 023507_4, 2012/02
Times Cited Count:10 Percentile:44.33(Instruments & Instrumentation)Tojo, Hiroshi; Hatae, Takaki; Itami, Kiyoshi
Plasma and Fusion Research (Internet), 6, p.1302018_1 - 1302018_3, 2011/05
A new method of in-situ relative calibration for Thomson scattering diagnostics using a double-pass scattering system is proposed. Ratio of scattered light signals between the first and second pass depend on electron temperature (): thereby making evaluation of without considering relative transmissivities possible. Determination of relative transmissivities of each spectral channel can be assigned at the same time. Feasibility of the method based on parameters in a JT-60SA Thomson scattering diagnostic is also examined.
Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Itami, Kiyoshi; Aida, Yoshiaki*; Suito, Satoshi*; Fujie, Daijiro*
Review of Scientific Instruments, 81(10), p.10D539_1 - 10D539_3, 2010/10
Times Cited Count:10 Percentile:44.26(Instruments & Instrumentation)Designs of collection optics for JT-60SA Thomson scattering system are presented. By using tangential (to the toroidal direction) YAG laser injection, three collection optics without strong chromatic aberrations generated by the wide viewing angle and small design volume measure almost all the radial space. For the edge plasma measurements, we optimized the channel number and wavelength ranges of band-pass filters in polychromator to reduce relative error in the electron temperature by considering the all spatial channels and double-pass laser system with different geometric parameters.
Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Itami, Kiyoshi
Journal of Plasma and Fusion Research SERIES, Vol.9, p.288 - 293, 2010/08
Significant loss in transmissivity of the used fiber after the 18 years operations in JT-60U are found. Therefore, an optimization of the filter's configuration of the polychromator in Thomson scattering system for the high performance plasmas in JT-60SA is an essential task. Especially, loss in optical components induced by radiation from neutrons and -ray should be examined. In this paper, an optimization of the filter configuration in the polychromator is executed and expected error degradation due to the radiation damages in the measurements are also estimated with a comparison between used fibers in JT-60U and radiation resistance fibers. In 10 keV, the time evolution of the averaged relative errors for the radiation resistance fibers increase from 35% by . However, for the used fibers in JT-60U, the errors are 78% and they reaches more than 10% in some high conditions, suggesting some difficulties in the measurements.
Miyazaki, Itaru*; Sakane, Hitoshi*; Takayama, Hirokazu*; Kasaishi, Masafumi*; Tojo, Akinori*; Furuta, Masataka*; Hayashi, Hiroaki*; Suematsu, Osamu*; Narasaki, Hiromichi*; Shimizu, Toshiaki*; et al.
Journal of Nuclear Science and Technology, 45(6), p.481 - 486, 2008/06
Times Cited Count:5 Percentile:35.13(Nuclear Science & Technology)The intensities of the prompt rays from the N(n,)N reaction have been precisely measured. As the samples, a liquid nitrogen target and a deuterated melamine (CDN) were used. The previous values widely used as intensity standards agreed with those obtained in this study within 4-5% in the 2-11 MeV region, however, showed a monotonous decrease with the increase of -ray energy.
Hatae, Takaki; Yamada, Ichihiro*; Yoshida, Hidetsugu*; Narihara, Kazumichi*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Funaba, Hisamichi*; Minami, Takashi*; Kajita, Shin*; Tojo, Hiroshi; et al.
no journal, ,
no abstracts in English
Tojo, Hiroshi; Hatae, Takaki; Sakuma, Takeshi; Hamano, Takashi; Shinohara, Koji; Itami, Kiyoshi; Aida, Yoshiaki*; Suito, Satoshi*; Fujie, Daijiro*
no journal, ,
Conceptual designs of the collection optics for JT-60SA Thomson scattering have been done. Adapting four glass materials of the lenses used for the collection optics enables to correct the chromatic aberrations with good resolution ( 1 mm). The whole radial profile can be measured using three designed collection optics in Port-P1, P2 and P5. The collection optics will be installed in port-plugs accessing from the cryostat to vacuum vessel. In a disruption with a decrease of the plasma current by a time scale of 5 MA/8 ms, the eddy current (0.1 MA/m) is strongly generated in the area of 500 mm from the edge of the port-plug with the thickness of 30 mm. Even if the thickness is reduced to 20 mm decreasing the current in the area, the maximum principal stress is still under the limit value for the design.
Hatae, Takaki; Kitamura, Shigeru; Sakuma, Takeshi; Hamano, Takashi; Tojo, Hiroshi; Yoshida, Hidetsugu*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Narihara, Kazumichi*; Yamada, Ichihiro*; et al.
no journal, ,
Tojo, Hiroshi; Hatae, Takaki; Itami, Kiyoshi
no journal, ,
no abstracts in English
Itami, Kiyoshi; Shinohara, Koji; Hatae, Takaki; Kamiya, Kensaku; Fukumoto, Masakatsu; Nakano, Tomohide; Yoshida, Maiko; Tojo, Hiroshi; Arakawa, Hiroyuki; Kokusen, Shigeharu; et al.
no journal, ,
Nakano, Tomohide; Yoshida, Maiko; Itami, Kiyoshi; Kamiya, Kensaku; Shinohara, Koji; Tojo, Hiroshi; Hatae, Takaki; Fukumoto, Masakatsu
no journal, ,
In high density plasmas of JT-60SA, it is probable that the measurement of ion temperature and rotation velocity by charge exchange recombination spectroscopy is difficult at the center of the plasmas because of significant decay of heating neutral beam. Here we calculated the decay of the neutral beam and synthesized C VI (=7-8) spectral line. Due to high intensity of bremsstrahlung emission, it was found that the syntesized C VI (=7-8) spectrum was undistinguishable from the noise of the bremsstrahlung emission. This led to significant uncertainties of the ion temperature and the rotation velocity, evaluated from the Doppler width and shift, respectively. It was also found that the uncertainties of the ion temperature and the rotation velocity decrease down to the required level described in JT-60SA research plan at normalized plasma radius of and , respectively.
Tojo, Hiroshi; Ejiri, Akira*; Hiratsuka, Junichi*; Yamaguchi, Takashi*; Takase, Yuichi*; Itami, Kiyoshi
no journal, ,