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Ogawa, Shuichi*; Taga, Ryo*; Yoshigoe, Akitaka; Takakuwa, Yuji*
Journal of Vacuum Science and Technology A, 39(4), p.043207_1 - 043207_9, 2021/07
Times Cited Count：1 Percentile：7.12(Materials Science, Coatings & Films)Nickel (Ni) is used as a catalyst for nitric oxide decomposition and ammonia production but it is easily oxidized and deactivated. Clarification of the reduction process of oxidized Ni is essential to promote more efficient use of Ni catalysts. In this study, the reduction processes were investigated by in situ time-resolved photoelectron spectroscopy. We propose a two-step reduction reaction model. The rate-limiting process for the first step is surface precipitation of O atoms and that of the second step is dissociation of H
molecules.
Matsumoto, Masuaki*; Fukutani, Katsuyuki; 6 of others*
Journal of Vacuum Science and Technology A, 37(5), p.051601_1 - 051601_6, 2019/09
Times Cited Count：5 Percentile：26.74(Materials Science, Coatings & Films)Kamiya, Junichiro; Kinsho, Michikazu; Abe, Kazuhiko*; Higa, Kyusaku*; Koizumi, Oji*
Journal of Vacuum Science and Technology A, 36(3), p.03E106_1 - 03E106_10, 2018/05
Times Cited Count：0 Percentile：0.01(Materials Science, Coatings & Films)The 3 GeV Rapid Cycling Synchrotron (RCS) in J-PARC aims to generate one of the highest power protons in the world, whose design extraction beam power is 1 MW. Beam pipes of alumina ceramics are used to prevent the induced current, which is caused by the rapid change of the magnetic field. In the beam injection section, ceramics beam pipes for a quadrupole magnet and a horizontal shift bump magnet are connected without bellows due to the very limited space. To improve maintainability, the ceramics beam pipes for the quadrupole magnet were newly designed to insert the bellows. We will report the design concept of the new alumina ceramics beam pipes with low spring constant bellows and the several results of the verification tests.
Morishita, Takatoshi; Kondo, Yasuhiro; Oguri, Hidetomo; Hasegawa, Kazuo
Journal of Vacuum Science and Technology A, 35(4), p.041602_1 - 041602_5, 2017/07
Times Cited Count：1 Percentile：4.82(Materials Science, Coatings & Films)In the J-PARC, the linac provides 400 MeV hydrogen negative ion beam to the following 3GeV synchrotron. For the beam current upgrade, the new radio-frequency quadrupole (RFQ) linac, in which the design peak beam current was increased from 30 to 50 mA, has been fabricated and installed in the beam line in summer 2014. The beam provision to users started in the beginning of November, 2014. Since then, the RFQ operates without serious problems for more than two years, however, the operation stability of the RFQ with beam acceleration was not enough due to the sparking in the cavity. We consider that the impurities in the vacuum chamber are related to this sparking phenomena. The design and performance of the RFQ vacuum system is described in this paper, then, the relationship among the sparking rates, the residual gas species in the vacuum chamber, and the beam operation parameters are described.
baking method for degassing of a kicker magnet in accelerator beam lineKamiya, Junichiro; Ogiwara, Norio; Yanagibashi, Toru*; Kinsho, Michikazu; Yasuda, Yuichi*
Journal of Vacuum Science and Technology A, 34(2), p.021604_1 - 021604_10, 2016/03
Times Cited Count：3 Percentile：14.71(Materials Science, Coatings & Films)In this study, we propose a new 
degassing method by which only kicker magnets in the accelerator beam line are baked out without raising the temperature of the vacuum chamber to prevent unwanted heat expansion of the chamber. The bake-out system comprises the heater and thermal radiation shield plates, which are installed between the kicker magnet and the chamber wall. The result of the verification test showed that each part of the kicker magnet was heated to above the target temperature with a small rise in the vacuum chamber temperature. A graphite heater was selected in this application to bake-out the kicker magnet in the beam line to ensure reliability and easy maintainability of the heater. The vacuum characteristics of graphite were suitable for heater operation in the beam line. A preliminary heat-up test conducted in the accelerator beam line also showed that each part of the kicker magnet was successfully heated and that heat expansion of the chamber was negligibly small.
Kamiya, Junichiro; Hikichi, Yusuke; Kinsho, Michikazu; Ogiwara, Norio; Fukuda, Mitsuhiro*; Hamatani, Noriaki*; Hatanaka, Kichiji*; Kamakura, Keita*; Takahisa, Keiji*
Journal of Vacuum Science and Technology A, 33(3), p.031605_1 - 031605_8, 2015/05
Times Cited Count：5 Percentile：22.66(Materials Science, Coatings & Films)For the vacuum systems of high-intensity beam accelerators, low radioactivation materials with good vacuum characteristics and high mechanical strength are required. The titanium alloy Ti-6Al-4V was investigated as a potential low activation vacuum material with high mechanical strength for the fabrication of vacuum components, particularly the flanges of beam pipes, in the J-PARC 3 GeV synchrotron. The dose rate of Ti-6Al-4V when irradiated by a 400 MeV proton was observed to decrease more rapidly than that of stainless steel. Furthermore, the generated radioactive isotopes were nuclides with relatively short half-lives. The outgassing rate of Ti-6Al-4V was the same as the typical value for stainless steel. Additionally, the hydrogen concentration in bulk Ti-6Al-4V was reduced to approximately 1 ppm by vacuum firing. These results indicate that Ti-6Al-4V is a good candidate for use as a low activation vacuum material with high mechanical strength.
Oyama, Tomoko; Oshima, Akihiro*; Washio, Masakazu*; Tagawa, Seiichi*
Journal of Vacuum Science and Technology B, 31(4), p.041604_1 - 041604_5, 2013/07
Times Cited Count：9 Percentile：44.99(Engineering, Electrical & Electronic)Suemitsu, Maki*; Yamamoto, Yoshihisa*; Togashi, Hideaki*; Enta, Yoshiharu*; Yoshigoe, Akitaka; Teraoka, Yuden
Journal of Vacuum Science and Technology B, 27(1), p.547 - 550, 2009/02
Times Cited Count：4 Percentile：29.62(Engineering, Electrical & Electronic)Initial oxidation processes of the Si(110) surface and the chemical bonding states of silicon atoms in the initial oxides have been investigated by using real-time synchrotron-radiation photoemission spectroscopy. Time evolutions of the Si
(
=1-4) components in the Si 2
spectrum indicates that the Si
component always overwhelms the Si
component during the oxidation up to one monolayer. This is in sharp contrast to the Si(001) surface where Si is always larger than Si. The dominance of the Si component is related to presence of two types of bonds on the Si(110) surface and to their possible different reactivity against insertion of oxygen atoms.
4) phases investigated by 
surface X-ray diffractionTinkham, B. P.*; Braun, W.*; Ploog, K. H.*; Takahashi, Masamitsu; Mizuki, Junichiro; Grosse, F.*
Journal of Vacuum Science and Technology B, 26(4), p.1516 - 1520, 2008/07
Times Cited Count：3 Percentile：26.05(Engineering, Electrical & Electronic)Rocco, M. L. M.*; Sekiguchi, Tetsuhiro; Baba, Yuji
Journal of Vacuum Science and Technology A, 24(6), p.2117 - 2121, 2006/11
Times Cited Count：10 Percentile：37.16(Materials Science, Coatings & Films)no abstracts in English
Enomoto, Kazuyuki*; Moon, S.*; Maekawa, Yasunari; Shimoyama, Junji*; Goto, Kazuyuki*; Narita, Tadashi*; Yoshida, Masaru
Journal of Vacuum Science and Technology B, 24(5), p.2337 - 2349, 2006/09
Times Cited Count：5 Percentile：33.49(Engineering, Electrical & Electronic)The electron beam (EB)-induced reaction of triphenylsulfonium methanesulfonate (1-Ms) in the solid state afforded the benzene-substituted product, biphenyldiphenylsulfonium methanesulfonate (2-Ms), which has not been observed by either photolysis or EB-induced reaction in a solution. The kinetic data revealed that the biphenyl salt 2-Ms exhibited 3.7 times greater kinetic constants for consumption than that of 1-Ms. The EB-induced reaction of benzene-substituted triphenylsulfonium salts, p-biphenyldiphenylsulfonium methanesulfonate (2p-Ms) and (4-phenylthiophenyl)diphenyl- sulfonium methanesulfonate (7) showed the consumption rates of 3.8 and 5.7 times greater than that of 1-Ms. The sulfonium salts with aromatic counter anions showed somewhat higher reactivity than those with aliphatic counter anions. Accordingly, it is concluded that the triphenylsulfonium salts having aryl groups, which exhibit lower ionization potential (Ip), in both cation and anion moieties should exhibit greater decomposition rates.
Uddin, M. N.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nagano, Masamitsu*
Journal of Vacuum Science and Technology A, 23(3), p.497 - 502, 2005/05
Times Cited Count：39 Percentile：77.16(Materials Science, Coatings & Films)B-C-N hybrid thin films were grown from ion beam plasma of borazine (B
NH
) on graphite substrate at room temperature, 600
C, and 850C. The films were characterized by X-ray photoelectron spectroscopy (XPS). XPS study suggested that B and N atoms in the deposited films are in a wide variety of chemical bonds e.g., B-C, B-N, N-C, and B-C-N. The substrate temperature and ion fluence were shown to have significant effect on the coordination and elemental binding states on the B-C-N hybrids. It was found that B-C-N hybrid formation is enhanced at high temperature, and this component is dominantly synthesized at low fluence. The results imply that it is possible to control the composition of B-C-N hybrid by changing the ion fluence and the temperature during ion implantation.
Goniche, M.*; Kazarian, F.*; Bibet, P.*; Maebara, Sunao; Seki, Masami; Ikeda, Yoshitaka; Imai, Tsuyoshi*
Journal of Vacuum Science and Technology A, 23(1), p.55 - 65, 2005/01
Times Cited Count：2 Percentile：9.27(Materials Science, Coatings & Films)Outgassing rates have been measured for long duration (100-4700 seconds) of RF transmission at high power density (50-200 MW/m
) for waveguides made of OFHC copper, dispersoid copper, copper-coated carbon fiber composite and copper-coated graphite. The measurements were performed on multi-waveguide(2 to 8)mockups, using a test bed facility equipped with a 3.7 GHz klystron. The effect on the outgassing rate of waveguide surface temperature and of initial wall gas loading('conditioning'), is examined. It is concluded that an outgassing rate of 110
Pam
s
m
and 510 Pamsm at 300C and 400C respectively, can be expected for the tested material. Based on these measurement results, it is further concluded that no additional pumping will be needed for the LHRF antenna proposed for ITER.
Moritani, Kosuke; Okada, Michio*; Sato, Seiichi*; Goto, Seishiro*; Kasai, Toshio*; Yoshigoe, Akitaka; Teraoka, Yuden
Journal of Vacuum Science and Technology A, 22(4), p.1625 - 1630, 2004/08
Times Cited Count：25 Percentile：65.94(Materials Science, Coatings & Films)We studied the oxidation of Cu{111} surface with a hyperthermal O molecular beam (HOMB) using X-ray photoemission spectroscopy (XPS) in conjunction with a synchrotron radiation (SR) source. The efficiency of oxidation with 0.6-eV-HOMB is higher thab that with 2.3-eV-HOMB under 
0.5ML. Ont the other hand, further oxidation occurs rather inefficiency under 
0.5ML. In this region, efficiency of oxidation with 2.3-eV-HOMB is higher than 0.6-eV-HOMB. We found that such slow oxidation process of Cu can be interpreted in terms of a collision-induced-adsorption mechanism. These results suggest that we can control the oxidation process of Cu by using HOMB.
Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.; Sasaki, Masayoshi*; Okuno, Kenji*
Journal of Vacuum Science and Technology A, 21(6), p.1843 - 1848, 2003/11
Times Cited Count：6 Percentile：28.1(Materials Science, Coatings & Films)Ion implantation method is applied to synthesize B-C-N hybrids and their electronic structures are characterized by X-ray photoelectron spectroscopy. A boron nitride film is deposited on a graphite target by borazine plasma implantation. At the interface between the BN film and the graphite, variety of bonding combinations including B-N, B-C, and C-N are observed. This proved that B-C-N hybrids is formed by this method.
Kinsho, Michikazu; Nishizawa, Daiji*; Saito, Yoshio*; Suzuki, Hiromitsu; Yokomizo, Hideaki
Journal of Vacuum Science and Technology A, 20(3), p.829 - 832, 2002/06
Times Cited Count：16 Percentile：54.04(Materials Science, Coatings & Films)The 3 GeV synchrotron accelerator for JAERI-KEK joint project is aimed to supply a high-intensity proton beam to both the 50 GeV synchrotron ring and the neutron production target. For this purpose, the 3 GeV synchrotron, having a circumference of 313.5 m, is designed to accelerate a high-power beam of 1MW, by setting 25 Hz as a repetition rate and 8.3 x 1013 as a proton number for each acceleration. A rapid-cycling magnetic field is necessary to operate a synchrotron with such a high repetition rate. Since an eddy-current effect in a metal duct would produce an unacceptable perturbation of the magnetic field and unnecessarily large ohmic losses, an alumina ceramic is a candidate material for vacuum ducts in the dipole and quadrupole magnets. This paper discrives the design for the 3GeV synchrotron of JAWRI-KEK joint project.
Baba, Yuji; Wu, G.; Sekiguchi, Tetsuhiro; Shimoyama, Iwao
Journal of Vacuum Science and Technology A, 19(4), p.1485 - 1489, 2001/07
Times Cited Count：5 Percentile：26.27(Materials Science, Coatings & Films)no abstracts in English
)
by localized inner-shell electron excitation at the silicon, oxygen and carbon K-edgesBaba, Yuji; Sekiguchi, Tetsuhiro
Journal of Vacuum Science and Technology A, 18(2), p.334 - 337, 2000/03
Times Cited Count：4 Percentile：22.94(Materials Science, Coatings & Films)no abstracts in English
