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Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:3 Percentile:90.77

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:6 Percentile:92.96

Journal Articles

Performance test of automatic analysis system of strontium-90 in environmental sample

Fujita, Hiroki; Nojima, Takehiro; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*

KEK Proceedings 2016-8, p.168 - 172, 2016/10

An automatic analysis system was developed to analyze Strontium-90 ($$^{90}$$Sr) radioactivity in environmental sample for 2013-2015. Various kinds of ashed environmental samples were used in performance tests of the automatic system. These tests were successful without any system trouble. However, $$^{90}$$Sr concentration had not been measured using the samples analyzed by the system. In this research, $$^{90}$$Sr concentration in seaweed sample was compared by between the system's analysis and worker's one. Moreover, the system was improved in each analysis process.

Journal Articles

Non-destructive depth analysis of the surface oxide layer on Mg$$_{2}$$Si with XPS and XAS

Esaka, Fumitaka; Nojima, Takehiro; Udono, Haruhiko*; Magara, Masaaki; Yamamoto, Hiroyuki

Surface and Interface Analysis, 48(7), p.432 - 435, 2016/07

 Times Cited Count:7 Percentile:24.92(Chemistry, Physical)

XPS is widely used for non-destructive chemical state analysis of solid materials. In this method, depth profiling can be carried out by a combination with ion beam sputtering. However, the sputtering often causes segregation and preferential sputtering of atoms and gives inaccurate information. The use of energy-tunable X-rays from synchrotron radiation (SR) enables us to perform non-destructive depth profiling in XPS. Here, the analytical depth can be changed by changing excitation X-ray energy. In the present study, we examined methods to perform depth profiling with XPS by changing excitation energy and XAS by changing electron energy for detection. These methods were then applied to the analysis of native surface oxide layers on Mg$$_{2}$$Si crystals. In this XAS analysis, the peak at 1843.4 eV becomes dominant when the electron energy for detection increases, which implies that Si-O or Si-O-Mg structure is formed as the surface oxide layer on the Mg$$_{2}$$Si.

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 automatic analysis system of Strontium-90 in environmental sample

Nojima, Takehiro; Fujita, Hiroki; Nagaoka, Mika; Osawa, Takahito; Yokoyama, Hiroya; Ono, Hironobu*

KEK Proceedings 2015-4, p.111 - 115, 2015/11

Automatic strontium-90 analysis system was developed for environmental sample in this research. The system was successful to do wet ashing, chemical separation and ion exchange processes using robot, automatic heating system and so on. Hand-made control program can operate the system by itself.

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:11 Percentile:51.68(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

Thermal and optical analyses of retro-reflector for poloidal polarimeter on ITER

Imazawa, Ryota; Kawano, Yasunori; Ono, Takehiro; Kusama, Yoshinori

Plasma and Fusion Research (Internet), 6(Sp.1), p.2402032_1 - 2402032_5, 2011/08

This paper describes results from the first integrated analysis on the feasibility of a retro-reflector (RR) installed in the ITER vacuum vessel. We make thermal and structural analyses of passively-cooled RR and terrace retro-reflector array (TERRA) by using heat load conditions on ITER. In the case of RR, the temperature reaches over 600$$^{circ}$$C, and the flatness of deformed mirror surface forming RR is approximately 80 $$mu$$m. Although the maximal displacement of mirror surface is large, 69% of the incident-laser power returns to a diagnostic room, disturbance of phase is $$pi/4$$ and rotation angle of polarization plane is less than 0.06 $$^{circ}$$. On the other hand, the temperature of TERRA is approximately 350$$^{circ}$$C, and the flatness of the deformed mirror surface is less than 10 $$mu$$m. The flatness of the mirror surface of the deformed TERRA is much smaller than laser wavelength (118 $$mu$$m), but the global shape is curved to ruin the coherent phase of laser light. The curvature radius of TERRA is 21 m, and 49% of the incident-laser power returns to the diagnostic room, disturbance of phase is $$pi/5$$, and rotation angle of polarization plane is less than 0.06$$^{circ}$$. Since the optimized incident angles of flat and curved TERRA are different, a real-time feedback control of the incident angle is necessary for applying TERRA to ITER poloidal polarimeter.

Journal Articles

Terrace retro-reflector array for poloidal polarimeter on ITER

Imazawa, Ryota; Kawano, Yasunori; Ono, Takehiro; Kusama, Yoshinori

Review of Scientific Instruments, 82(2), p.023116_1 - 023116_5, 2011/02

 Times Cited Count:1 Percentile:7.72(Instruments & Instrumentation)

Journal Articles

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

Hatae, Takaki; Hayashi, Toshimitsu; Yatsuka, Eiichi; Kajita, Shin*; Yoshida, Hidetsugu*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Yahagi, Kenichi*; Shinobu, Katsuya*; Ono, Takehiro; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.253 - 258, 2010/08

Journal Articles

Evaluation of dependence of current decay time on electron temperature measured by He I line intensity ratios in JT-60U tokamak

Okamoto, Masaaki*; Hiraishi, Takehiro*; Ono, Noriyasu*; Takamura, Shuichi*; Nakano, Tomohide; Kawano, Yasunori; Ozeki, Takahisa; Sugihara, Masayoshi

Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00

It is of importance to evaluate the decay time of the plasma current for estimation of the electromagnetic force acting on the vacuum vessel during plasma disruptions in tokamak devices. The L/R model predicts that the decay time is proportional to three-haves power of the electron temperature, indicating the importance of the electron temperature for the estimation. However, it is difficult to measure the electron temperature of the disruptive plasma with the Langmuir probe due to the heat flux and due to the significant electromagnetic force. We propose a measurement technique of the electron temperature by using temperature-sensitive He I lines with high time resolution. In this method, the incident light to a spectrometer is divided into three, each of which transmits a bandpass filter, and then is measured with an absolutely calibrated photo-multiplier. The measured intensity ratios are analyzed with a collisional-radiative model. It is confirmed that the electron temperature determined by this technique is in agreement with that measured by a Langmuir probe in some devices. In the present work, the temporal evolution of the electron temperature during the disruptive plasma of JT-60U is measured with this technique.

JAEA Reports

Design report on the 3-GeV proton beam transport facility (3NBT) of High Intensity Proton Accelerator facility (J-PARC)

Sakamoto, Shinichi; Meigo, Shinichiro; Konno, Chikara; Kai, Tetsuya; Kasugai, Yoshimi; Harada, Masahide; Fujimori, Hiroshi*; Kaneko, Naokatsu*; Muto, Suguru*; Ono, Takehiro*; et al.

JAERI-Tech 2004-020, 332 Pages, 2004/03

JAERI-Tech-2004-020.pdf:17.93MB

One of the experimental facilities in Japan Proton Accelerator Research Complex (J-PARC) is the Materials and Life Science Experimental Facility (MLF), where high-intensity neutron beams and muon beams are used as powerful probes for materials science, life science and related engineering. The neutrons and muons are generated with high-intensity proton beam from 3-GeV rapid cycling synchrotron (RCS). The high-intensity proton beam has to be effectively transported, and a neutron production target and a muon production target have to be also properly irradiated. The principal design of the 3-GeV proton beam transport facility (3NBT) is systematized.

JAEA Reports

Study of technical issues on proton beam line tunnel in material/life science experimental facility of high intensity proton accelerator project

Sakamoto, Shinichi; Meigo, Shinichiro; Konno, Chikara; Harada, Masahide; Miyake, Yasuhiro*; Kasugai, Yoshimi; Muto, Suguru*; Fujimori, Satoru*; Ono, Takehiro; Ikeda, Yujiro

JAERI-Tech 2001-075, 168 Pages, 2001/12

JAERI-Tech-2001-075.pdf:12.78MB

no abstracts in English

Oral presentation

Experimental investigation of electron density and temperature measurement Using helium line intensity ratios in divertor simulator NAGDIS-II

Kajita, Shin*; Ono, Noriyasu*; Hiraishi, Takehiro*; Nakano, Tomohide; Takamura, Shuichi*

no journal, , 

no abstracts in English

Oral presentation

Measurement of electron temperature and density using He I line intensity ratio in tokamak plasmas

Hiraishi, Takehiro*; Okamoto, Masaaki*; Kajita, Shin*; Hasebe, Yu*; Ono, Noriyasu*; Takamura, Shuichi*; Nakano, Tomohide

no journal, , 

no abstracts in English

Oral presentation

Completion of J-PARC 1MW pulsed spallation neutron source proton beam transport facility

Meigo, Shinichiro; Fujimori, Hiroshi*; Kai, Tetsuya; Kasugai, Yoshimi; Oi, Motoki; Ono, Takehiro; Ikezaki, Kiyomi; Shinomiya, Kenji; Sakamoto, Shinichi

no journal, , 

no abstracts in English

Oral presentation

Beam transport to the proton beam dump at J-PARC 3GeV proton transport facility

Oi, Motoki; Kai, Tetsuya; Ono, Takehiro; Ikezaki, Kiyomi; Haraguchi, Tetsuya; Fujimori, Hiroshi*; Sakamoto, Shinichi; Meigo, Shinichiro

no journal, , 

no abstracts in English

Oral presentation

First neutrons yielding at JSNS in J-PARC, 3; Proton beam commissioning toward neutron source (JSNS)

Meigo, Shinichiro; Oi, Motoki; Kai, Tetsuya; Harada, Masahide; Ikezaki, Kiyomi; Haraguchi, Tetsuya; Fujimori, Hiroshi*; Sakamoto, Shinichi; Ono, Takehiro

no journal, , 

no abstracts in English

Oral presentation

Beam commissioning of spallation neutron source at J-PARC

Meigo, Shinichiro; Oi, Motoki; Kai, Tetsuya; Ono, Takehiro; Ikezaki, Kiyomi; Haraguchi, Tetsuya; Akutsu, Atsushi; Sakamoto, Shinichi; Fujimori, Hiroshi*

no journal, , 

no abstracts in English

Oral presentation

Development of YAG laser system for edge Thomson scattering diagnostics in ITER

Hatae, Takaki; Hayashi, Toshimitsu; Kajita, Shin*; Yoshida, Hidetsugu*; Fujita, Hisanori*; Nakatsuka, Masahiro*; Yahagi, Kenichi*; Shinobu, Katsuya*; Ono, Takehiro; Kusama, Yoshinori

no journal, , 

no abstracts in English

48 (Records 1-20 displayed on this page)