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Kondo, Hiroo*; Kanemura, Takuji*; Park, C. H.*; Oyaizu, Makoto*; Hirakawa, Yasushi; Furukawa, Tomohiro
Fusion Engineering and Design, 146(Part A), p.285 - 288, 2019/09
Times Cited Count：1 Percentile：10.65(Nuclear Science & Technology)Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion-corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.
Inoue, Takashi; Hanada, Masaya; Kashiwagi, Mieko; Nishio, Satoshi; Sakamoto, Keishi; Sato, Masayasu; Taniguchi, Masaki; Tobita, Kenji; Watanabe, Kazuhiro; DEMO Plant Design Team
Fusion Engineering and Design, 81(8-14), p.1291 - 1297, 2006/02
Times Cited Count：11 Percentile：60.07(Nuclear Science & Technology)Requirement and technical issues of the neutral beam inejctor (NBI) is discussed for fusion DEMO plant. The NBI for the fusion DEMO plant should be high efficiency, high energy and high reliability with long life. From the view point of high efficiency, use of conventional electrostatic accelerator is realistic. Due to operation under radiation environment, vacuum insulation is essential in the accelerator. According to the insulation design guideline, it was clarified that the beam energy of 1.5
2 MeV is possible in the accelerator. Development of filamentless, and cesium free ion source is required, based on the existing high current/high current density negative ion production technology. The gas neutralization is not applicable due to its low efficiency (60%). R&D on an advanced neutralization scheme such as plasma neutralization (efficiency: 
80%) is required. Recently, development of cw high power semiconductor laser is in progress. The paper shows a conceptual design of a high efficiency laser neutralizer utilizing the new semiconductor laser array.
Masuda, Shinichi; Kando, Masaki; Kotaki, Hideyuki; Nakajima, Kazuhisa
Physics of Plasmas, 12(1), p.013102_1 - 013102_6, 2005/01
Times Cited Count：22 Percentile：57.82(Physics, Fluids & Plasmas)no abstracts in English
beam with Nd:YAG laser in J-PARCTomisawa, Tetsuo; Akikawa, Hisashi; Sato, Susumu; Ueno, Akira; Kondo, Yasuhiro; Oigawa, Hiroyuki; Sasa, Toshinobu; Hasegawa, Kazuo; Lee, S.*; Igarashi, Zenei*; et al.
Proceedings of 7th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators (DIPAC 2005), p.275 - 277, 2005/00
The photo neutralization method with Nd:YAG laser for negative hydrogen ions has been expected as an available candidate for the transverse beam profile measurement. The fraction of photo detached electron can also be used for charge exchange procedure to extract very low power proton beam for Transmutation Experimental Facility in J-PARC. The laser system has advantages of maintenance and radiation hardness in high intensity proton accelerators. In order to establish the low power beam extraction system and beam profile monitor, the photo neutralization efficiency must be surveyed in practical beam line with high intensity H beam. In this paper, an experimental set-up and preliminary results of photo neutralization method for intense H beam in J-PARC MEBT1 are described.
Oka, Kiyoshi; Shibanuma, Kiyoshi
JAERI-Tech 2003-004, 57 Pages, 2003/03
JAERI-Tech-2003-004.pdf:2.36MB
Cesium is required in order to generate a stable negative ion of hydrogen in an ion source of the neutral beam injector (NBI), which is one of the plasma-heating devices for International Thermonuclear Experimental Reactor (ITER). After long time operation of NBI, the cesium deposits to the insulators supporting the electrode. Due to the deterioration of the insulation resistance, the continuous operation of the NBI will be difficult. In addition, the NBI device is activated by neutron from D-T plasma, so that a periodic removal and cleaning of the cesium on the insulators by remote handling is required. A study of the cesium removal scenario and device is therefore required considering remote handling. In this report, a cesium removal procedure and conceptual design of the cesium removal device using laser ablation technique are studied, and the feasibility of laser ablation is shown.
Kotaki, Hideyuki
JAERI-Research 2002-031, 88 Pages, 2002/12
JAERI-Research-2002-031.pdf:3.33MB
We investigate a nonlinear phenomena in laser-plasma interaction, a wakefield excited by intense laser pulses, and a possibility of generating an electron beam by an intense laser pulse. Ionization of gas with a self-focusing causes a broad continuous spectrum with blueshift. The normal blueshift depends on the laser intensity and the plasma density. We have found the spectrum shifts to fixed wavelength independent of the laser power and gas pressure. We call the phenomenon "anomalous blueshift". An intense laser pulse excites a wakefield in plasma. The wakefield excited by 2TW, 50fs laser pulses in a gas-jet plasma is measured with a time-resolved frequency domain interferometer (FDI). This is the first time-resolved measurement of the wakefield of 20GeV/m in a gas-jet plasma. The FDI and the anomalous blueshift will be modified to an optical injection system as an electron beam injector. In a simulation we obtain a high quality intense electron beam. The result illuminates the possibility of a high energy and a high quality electron beam acceleration.
Yoshikawa, Kiyoshi*; Inoue, Nobuyuki*; Yamazaki, Tetsuo*; Makino, Keisuke*; Yamamoto, Yasushi*; Toku, Hisayuki*; Masuda, Kai*; Kii, Toshiteru*; Onishi, Masami*; Horiike, Hiroshi*; et al.
JAERI-Tech 2002-020, 63 Pages, 2002/03
JAERI-Tech-2002-020.pdf:4.94MB
no abstracts in English
Naramoto, Hiroshi; Xu, Y.; Narumi, Kazumasa; Vacik, J.; Zhu, X.; Yamamoto, Shunya; Miyashita, Kiyoshi*
Materials Research Society Symposium Proceedings, Vol.647, p.O5.18.1 - O5.18.16, 2001/00
no abstracts in English
thin films prepared in different ambients by laser ablationDai, Z.*; Naramoto, Hiroshi; Yamamoto, Shunya; Narumi, Kazumasa; Miyashita, Atsumi
Journal of Physics; Condensed Matter, 11(3), p.913 - 925, 1999/00
Times Cited Count：4 Percentile：28.62(Physics, Condensed Matter)no abstracts in English
epitaxial thin film onto sapphire substrateDai, Z.*; P.Zhu*; Yamamoto, Shunya; Miyashita, Atsumi; Narumi, Kazumasa; Naramoto, Hiroshi
Thin Solid Films, 339(1-2), p.114 - 116, 1999/00
Times Cited Count：28 Percentile：78.38(Materials Science, Multidisciplinary)no abstracts in English
Yoshida, Hidetoshi; Naito, Osamu; Matoba, Toru; Yamashita, Osamu; Kitamura, Shigeru; Hatae, Takaki; Nagashima, Akira
Review of Scientific Instruments, 68(2), p.1152 - 1161, 1997/02
Times Cited Count：13 Percentile：68.07(Instruments & Instrumentation)no abstracts in English
March 31, 1995JAERI-Review 95-015, 67 Pages, 1995/10
JAERI-Review-95-015.pdf:2.01MB
no abstracts in English
Nishimura, Akihiko; Shibata, Takemasa
Journal of Nuclear Science and Technology, 32(9), p.905 - 911, 1995/09
Times Cited Count：2 Percentile：28.03(Nuclear Science & Technology)no abstracts in English
Kunugi, Tomoaki;
Nihon Kikai Gakkai Rombunshu, B, 61(585), p.1826 - 1833, 1995/05
no abstracts in English
Akiba, Masato; Madarame, Haruki*
Journal of Nuclear Materials, 212-215(1), p.90 - 96, 1994/09
no abstracts in English
JAERI-M 94-017, 58 Pages, 1994/03
no abstracts in English
Minehara, Eisuke; Nagai, Ryoji; Sawamura, Masaru; Takao, Masaru*; Sugimoto, Masayoshi; Sasaki, Shigemi; Okubo, Makio; Kikuzawa, Nobuhiro; ; Suzuki, Yasuo; et al.
Shin Zairyo Kaihatsu O Mezasu Ion, Reza Bimu Gijutsu Ni Kansuru Shimpojiumu Hobunshu, 0, p.163 - 166, 1994/00
no abstracts in English
Nishimura, Akihiko; Arisawa, Takashi; Oba, Hironori; Shibata, Takemasa
J. Vac. Sci. Technol., A, 11(4), p.1516 - 1521, 1993/07
no abstracts in English
Sekine, Toshiaki; Koizumi, Mitsuo; ;
KURRI-TR-377, 0, p.19 - 21, 1993/04
no abstracts in English
Nishimura, Akihiko; Oba, Hironori; Shibata, Takemasa
Journal of Nuclear Science and Technology, 29(11), p.1054 - 1060, 1992/11
no abstracts in English
