Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Kamiya, Junichiro; Takano, Kazuhiro; Yuza, Hiromu*; Wada, Kaoru
Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.3471 - 3474, 2021/08
The NEG coating, which has been developed in CERN, is a revolutionary technique that can make a beam pipe act as a vacuum pump by coating the getter materials with the ability to adsorb/absorb gas molecules on the beam pipe surface. The NEG materials are alloys of titanium, zirconium, and vanadium. Titanium is one of the getter materials. In high-power beam accelerators, titanium has been used as the beam pipe chamber material due to its low radioactivation characteristics. The ordinal titanium surface has no getter function because it is covered with titanium-oxide film. The new technique, which removes the titanium-oxide surface by the sputtering and makes the titanium vacuum chamber itself the vacuum pump like NEG coated chamber, has been developed. After sputtering the inner surface of the titanium chamber, we obtained clear evidence that shows the chamber acts as a vacuum pump. We have also tried to make a titanium chamber with a getter function only by baking. Dependence of the getter characteristics on the baking temperature will also be reported.
Shimizu, Noritaka*; Tsunoda, Yusuke*; Utsuno, Yutaka; Otsuka, Takaharu*
Physical Review C, 103(1), p.014312_1 - 014312_11, 2021/01
Times Cited Count：17 Percentile：93.46(Physics, Nuclear)no abstracts in English
Kawaguchi, Munemichi; Saito, Junichi; Daido, Hiroyuki*; Suemoto, Toru*
UVSOR-47, P. 85, 2020/08
To elucidate theoretically the transparent metallic sodium in the vacuum ultraviolet (VUV) spectral range, the aim of this research is to obtain the accurate spectrum using UVSOR. We confirmed the validity for the transmittance measurement in UVSOR by the measurement of transmittance of CaF
windows. However, the transparency phenomenon of VUV in the metallic sodium has never been confirmed by our group. In the future, we will improve the sodium sample and conduct the measurement again.
Kawaguchi, Munemichi; Saito, Junichi; Daido, Hiroyuki*; Suemoto, Toru*
UVSOR-46, P. 89, 2019/08
To elucidate theoretically the transparent metallic sodium in the vacuum ultraviolet spectral range, the aim of this research is to obtain the accurate spectrum using UVSOR. The sodium sample maintained metallic luster by designing the special cells to prevent from oxidizing. The results of UVSOR measurement showed the possibility to occur the intransparent layer for vacuum ultraviolet light on the MgF windows. In the near future, we will improve the sodium sample to solve the problems and conduct the measurement again
Kinsho, Michikazu; Kamiya, Junichiro; Abe, Kazuhiko*; Nakamura, Tomaru*
Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.4161 - 4163, 2019/06
Alumina ceramics vacuum chamber which is used for the 3GeV rapid-cycling synchrotron (RCS) in J-PARC is composed of alumina duct, titanium (Ti) flanges and Ti sleeves. Before brazing the alumina duct and the Ti sleeves, the Ti sleeves were treated with nitric hydrofluoric acid. The purpose of this study is to clear the effect of this treatment for titanium material. It was cleared by SEM observation that the roughness of the titanium material after the nitric hydrofluoric acid treatment becomes big. It was also measured that the thickness of oxide film on surface of the titanium material was 12.7 nm before treatment and 6.0 nm after treatment. It became clear that both the clearing of oxide layer on the alumina ceramics and the vacuum condition of the vacuum heating furnace were important for brazing between alumina ceramics and pure titanium.
Itakura, Ryuji*; Kumada, Takayuki; Nakano, Motoyoshi*; Akagi, Hiroshi*
High Power Laser Science and Engineering, 4, p.e18_1 - e18_5, 2016/06
Times Cited Count：4 Percentile：25.13(Optics)We demonstrate that the methodology of frequency-resolved optical gating (FROG) is applicable to time-resolved reflection spectroscopy of a plasma mirror in the vacuum-ultraviolet (VUV) region. Our recent study has shown that a VUV waveform can be retrieved from a VUV reflection spectrogram of a plasma mirror formed on a fused silica (FS) surface by irradiation with an intense femtosecond laser pulse. Simultaneously, the increase in the reflectivity with respect to the Fresnel reflection of the unexcited FS surface can be obtained as a time-dependent reflectivity of the plasma mirror. In this study, we update the FROG analysis procedure using the least-square generalized projections algorithm. This procedure can reach convergence much faster than the previous one and has no aliasing problem. It is demonstrated that a significantly chirped VUV pulse as long as 1 ps can be precisely characterized.
Kojima, Atsushi; Hanada, Masaya; Tobari, Hiroyuki; Nishikiori, Ryo; Hiratsuka, Junichi; Kashiwagi, Mieko; Umeda, Naotaka; Yoshida, Masafumi; Ichikawa, Masahiro; Watanabe, Kazuhiro; et al.
Review of Scientific Instruments, 87(2), p.02B304_1 - 02B304_5, 2016/02
Times Cited Count：11 Percentile：48.77(Instruments & Instrumentation)Optimization techniques of the vacuum insulation design have been developed in order to realize a reliable voltage holding capability of Multi-Aperture Multi-Grid accelerators for giant negative ion sources for nuclear fusion. In this method, the nested multilayer configuration of each acceleration stage in the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages were based on the past experimental results of the area effect and the multi-aperture effect on the voltage holding capability. Moreover, total voltage holding capability of multi-stage was estimated by taking the multi-stage effect into account, which was experimentally obtained in this time. In this experiment, the multi-stage effect appeared as the superposition of breakdown probabilities in each acceleration stage, which suggested that multi-stage effect can be considered as the voltage holding capability of the single acceleration gap having the total area and aperture. The analysis on the MAMuG accelerator for JT-60SA agreed with the past gap-scan experiments with an accuracy of less than 10% variation.
Itakura, Ryuji; Kumada, Takayuki; Nakano, Motoyoshi*; Akagi, Hiroshi
Optics Express (Internet), 23(9), p.10914 - 10924, 2015/05
Times Cited Count：17 Percentile：65.18(Optics)We propose and experimentally demonstrate a method for characterizing vacuum ultraviolet (VUV) pulses based on time-resolved reflection spectroscopy of fused silica pumped by an intense laser pulse. Plasma mirror reflection is used as an ultrafast optical switch, which enables us to measure frequency-resolved optical gating (FROG) traces. The VUV temporal waveform can be retrieved from the measured FROG trace using principal component generalized projections algorithm with modification. The temporal profile of the plasma mirror reflectivity is also extracted simultaneously.
Inoue, Takashi
Kyoka Purasuchikkusu, 60(7), p.269 - 270, 2014/07
In ITER as a thermonuclear fusion experimental reactor being conducted by an international project, a large bore insulator ring of about 1.8 m in diameter is required for generation of 1 MeV, 40 A ion beam for plasma heating by Neutral Beam Injector. At JAEA, R&D has been carried out for development of such large bore insulator ring made of ceramics, and in parallel, ion beam experiments have been carried out with insulator rings made of FRP. The experiments have troubled with frequent high voltage breakdowns after outgas from FRP. Finding melt epoxy traces at triple junction (interface of vacuum, metal and FRP as dielectric material), local stress at the triple junction has been mitigated by mounting a large metal structure, so called stress ring. As a result, acceleration of 0.98 MeV, 185 A/m
hydrogen negative ion beam has successfully achieved in short pulses, where the requirement by ITER is 1 MeV and 200 A/m.
Kamiya, Junichiro; Kinsho, Michikazu; Noshiroya, Shiyoji; Yamamoto, Kazami
Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.2338 - 2340, 2014/07
In high power beam accelerators, pressure of the beam line directly affects the amount of the beam loss. J-PARC RCS is one of the most high power beam accelerators in the world. It aims the 1MW beam power, which corresponds to the average and peak beam current of 333 
A and about 10 A, respectively. In the present stage, the injection line called L3BT line (Linac to 3GeV Beam Transport line), is the section, where the pressure notably produces the beam loss. In this section, H
beam from Linac was converted to H
beam by charge stripping due to the interaction between H beam and the residual gas molecules. Such H beam was not bended by the injection septum magnets and directly hit the vacuum wall. We decided to add the vacuum pumps in this section to reduce the residual gas molecules in the beam line. In this paper, we will present the effectivity of the additional pumps by showing the relation between the beam line pressure and beam loss.
Kinsho, Michikazu; Saito, Yoshio*; Kabeya, Zenzaburo*; Ogiwara, Norio
Vacuum, 81(6), p.808 - 811, 2007/02
Times Cited Count：7 Percentile：30.05(Materials Science, Multidisciplinary)It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section of 378 mm inner diamater for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. The radio-frequency shield is designed as a high frequency pass filter, where eddy currents cannot be generated. In this shield one end of each strope is connected to a titanium flange with a capacitor to interrupt the eddy current loop. With this, the impedance of the duct with the radio-frequency shield was reduced within an allowable desgin limit. In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.
Nakamura, Hirofumi; Higashijima, Satoru
Shinku, 49(2), p.62 - 68, 2006/02
no abstracts in English
Ioki, Kimihiro*; Elio, F.*; Maruyama, So; Morimoto, Masaaki*; Rozov, V.*; Tivey, R.*; Utin, Y.*
Fusion Engineering and Design, 74(1-4), p.185 - 190, 2005/11
Times Cited Count：5 Percentile：35.66(Nuclear Science & Technology)The ITER project has started preparation of Procurement Specification Documents for the vacuum vessel (VV). The design of the VV and FW/Blanket has progressed in many aspects, such as an double curvature pressing instead of facet shape welding for inner and outer shells in the upper and lower inboard regions to improve the fabrication and NDT process. The plasma facing surface of the FW has been defined to avoid protruding the leading edges, especially in the inboard area. Separate FW panels are supported with a central beam, and selection of a race-track shape cross-section for the central beam provides a more robust structure against halo current EM loads and also leads to a new cooling configuration in the shield block, where the pressure drop is significantly reduced to 
0.05 MPa. A UT R&D program is also going on to achieve acceptable S/N ratio for small-angle launching waves (20-30 deg.) to a weld. Hydraulic testing has been performed to demonstrate natural convection cooling in the transient condition.
Koike, Masato; Sano, Kazuo*
Dai-5-Han Jikken Kagaku Koza 10; Busshitsu No Kozo 2, Bunko (Ge), 10, p.106 - 153, 2005/08
The chapter provides the basic knowledge of "vacuum ultraviolet spectrometers" and "ray racing" for young scientists without reading the numerous references and is intend to be the handbook for the specialist in various related sciences when they initiate spectroscopic experiments in the vacuum ultraviolet region. The content includes the basis of diffraction gratings, Optical properties of diffraction gratings, aberration theories, diffraction efficiency theories, basis of spectrometers, vacuum ultraviolet plane grating spectrometers, vacuum ultraviolet concave grating spectrometers, soft X-ray plane grating spectrometers, soft X-ray concave grating spectrometers, basis of ray tracing, applications of ray tracing, analytic design method, hybrid design method, etc.
Nakagawa, Kazumichi*; Kaneko, Fusae*; Ota, Yoshimi*; Tanaka, Masahito*; Kitada, Tomo*; Agui, Akane; Fujii, Kentaro; Yokoya, Akinari; Watanabe, Kazutoshi*; Yamada, Toru*
Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.271 - 273, 2005/06
Times Cited Count：12 Percentile：50.31(Spectroscopy)no abstracts in English
Kaneko, Fusae*; Tanaka, Masahito*; Narita, Satoru*; Kitada, Tomo*; Matsui, Takahiro*; Nakagawa, Kazumichi*; Agui, Akane; Fujii, Kentaro; Yokoya, Akinari
Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.291 - 294, 2005/06
Times Cited Count：19 Percentile：64.5(Spectroscopy)no abstracts in English
Yagisawa, Hiroshi; Arai, Takashi; Goto, Yoshitaka*
Heisei-16-Nendo Osaka Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 4 Pages, 2005/03
no abstracts in English
Sukegawa, Kota*; Kishimoto, Maki; Kado, Masataka
JAERI-Tech 2004-077, 21 Pages, 2005/01
JAERI-Tech-2004-077.pdf:4.17MB
no abstracts in English
Kinsho, Michikazu; Ogiwara, Norio; Saito, Yoshio*; Kabeya, Zenzaburo*
Proceedings of 2005 Particle Accelerator Conference (PAC '05) (CD-ROM), p.2604 - 2606, 2005/00
It was success to develop alumina ceramics vacuum ducts for the 3GeV-RCS of J-PARC at JAERI. There are two types of alumina ceramics vacuum ducts needed, one being 1.5m-long duct with a circular cross section for use in the quadrupole magnet, the other being 3.5m-long and bending 15 degrees, with a race-track cross section for use in the dipole magnet. These ducts could be manufactured by joining several duct segments of 0.5-0.8 m in length by brazing. The alumina ceramics ducts have copper stripes on the outside surface of the ducts to reduce the duct impedance. In order to reduce emission of secondary electrons when protons or electrons strike the surface, TiN film is coated on the inside surface of the ducts.
analyses with ferromagnetic and plasma rotation effects and wall geometry for a high steady state tokamakKurita, Genichi; Bialek, J.*; Tsuda, Takashi; Azumi, Masafumi; Ishida, Shinichi; Navratil, G. A.*; Sakurai, Shinji; Tamai, Hiroshi; Matsukawa, Makoto; Ozeki, Takahisa; et al.
IAEA-CN-116/FT/P7-7 (CD-ROM), 8 Pages, 2004/11
The critical beta is shown to be decreased by ferromagnetic effect by about 8 % for m/m02, m and m0 denote the permeability of ferromagnetic wall and vacuum, respectively, for tokamak of aspect ratio 3. The existence of the stability window opened by both effects of the toroidal plasma rotation and the plasma dissipation, which was not observed for high aspect ratio tokamak, is found for tokamak of aspect ratio 3. The effect of ferromagnetism on them is also investigated. The critical beta analyses of NCT (National Centralized Tokamak) plasma using VALEN code are started with stabilizing plate and vacuum vessel geometry with finite resistivity, and the results for passive effect of stabilizing plate are obtained. The calculations including stabilizing effect of the vacuum-vessel and also active feedback control are also performed for present design of NCT plasma.
