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Kamiya, Junichiro; Kinsho, Michikazu; Yamazaki, Yoshio; Yoshimoto, Masahiro; Yanagibashi, Toru*
Journal of the Vacuum Society of Japan, 60(12), p.484 - 489, 2017/12
Multi-turn H
charge exchange injection is employed as a beam injection method in the 3-GeV RCS (Rapid cycling synchrotron) at J-PARC (Japan Proton Accelerator Research Complex). In this method, injection H beam is put on the same orbit as already circulating proton (H
) beam in a dipole magnetic field due to the opposite curvature of the injected and circulating beams. In the straight section, where the two beams coincide with each other, both beams are passed through a thin foil, which strips two weakly bound electrons off each H ion, forming an intense beam of protons. The thin foil, which is mostly made of carbon, would be the source of the outgassing, especially when its temperature rises due to the beam hitting. Therefore it is important to estimate the amount and components of the outgassing from the charge stripping foil. In this paper, we will report the thermal desorption measurement results for the several foil, which is used as the charge stripping foil in the RCS.
Ogiwara, Norio; Hikichi, Yusuke*; Kamiya, Junichiro; Kinsho, Michikazu; Yoshida, Hajime*; Arai, Kenta*
Journal of the Vacuum Society of Japan, 60(12), p.475 - 480, 2017/12
Kamiya, Junichiro
Journal of the Vacuum Society of Japan, 59(8), p.213 - 221, 2016/08
Basic role of the vacuum systems in conventional particle accelerators is to maintain enough low pressure in the beam lines to guarantee the beam lifetime. In high power proton beam accelerators, the requirement for the vacuum system is much tougher due to the large size vacuum devices and high radioactivation. In addition, it is essential to pre-treat the vacuum materials in order to suppress pressure instability due to gas desorption from the vacuum wall originating from the large amount of the charged particles. Further, the rapid evacuation from the atmospheric pressure to the UHV after maintenance is also required to ensure the beam operation time. We aim to present the typical vacuum technologies in high power proton beam accelerator by introducing the vacuum system of J-PARC, especially of 3GeV rapid cycling synchrotron (RCS).
Ogiwara, Norio; Hikichi, Yusuke; Kamiya, Junichiro; Kinsho, Michikazu
Journal of the Vacuum Society of Japan, 59(4), p.79 - 82, 2016/04
Fukaya, Yuki
Journal of the Vacuum Society of Japan, 59(2), p.35 - 39, 2016/02
no abstracts in English
Ogiwara, Norio
Journal of the Vacuum Society of Japan, 58(5), p.168 - 172, 2015/05
The angular distribution of molecules emitted from rotating disks with a small gap was simulated using the Monte Carlo method. As the molecules have a circumferential velocity 
(: distance from the rotating axis and : angular velocity), when they leave the surfaces of the rotating disks, they tend to be emitted toward the tangent lines of the rims of the disks. When the disks rotate with a velocity ratio 
/ 
(: radius of the disk and : mean velocity of the molecules) of 3.8, three quarters of the outgoing molecules gather within an angle of 0.4 radians from the tangent line. The angular distribution is related to the altitude almost independent of the revolution frequency with a value of less than 2, where the rotating vector is specified to be oriented to zenith.
Kamiya, Junichiro; Ogiwara, Norio; Hikichi, Yusuke; Yanagibashi, Toru; Kinsho, Michikazu
Journal of the Vacuum Society of Japan, 58(4), p.134 - 139, 2015/04
This report aims to propose a new in situ degassing method by which only the kicker magnets were baked out without raising the temperature of the vacuum chamber by installing heat source and heat shield between the kicker magnet and the chamber wall. The target temperature of the ferrites in the kicker magnet is above 100
C, while keeping the temperature rise of the vacuum chamber less than 30C in order to prevent the heat expansion of the vacuum chamber. After checking the operability of this method by thermal analysis with simple model, the experimental measurement was performed by using a RCS kicker magnet. The results showed that the target temperature was able to be achieved by this degassing method.
Kobata, Masaaki; Kobayashi, Keisuke*
Journal of the Vacuum Society of Japan, 58(2), p.43 - 49, 2015/02
We report the applications of a hard X-ray photoelectron spectroscopy to the characterization of SiO
/Si(001)systems. Large escape depth of high-energy photoelectron enables us to probe buried layers and their interfaces in multilayer structures. Estimation of SiO overlayer thicknesses up to 25 nm by angle resolved XPS was possible in SiO/Si(001) samples. Determination of the thickness profile of a wedged shape SiO buried layer was successfully done in Ir (8 nm)/HfO (2.2 nm)/thickness graded-SiO (0-10 nm) / Si (100). The Si 1s core level showed a SiO thickness dependent shift, which was ascribed to fixed charge at the SiO-Si interface. Energy distribution of interface states at ultrathin thermal oxide/Si(100) interfaces were determined by Si 1
core level shift by applying gate bias in metal-oxide-semiconductor (MOS) structure with 5 nm Au gate electrodes.
Kamiya, Junichiro; Kinsho, Michikazu; Hayashi, Naoki; Hotchi, Hideaki; Ogiwara, Norio; Tani, Norio; Watanabe, Yasuhiro
Journal of the Vacuum Society of Japan, 57(4), p.131 - 135, 2014/04
In J-PARC 3GeV synchrotron (RCS), new quadrupole magnets (quadrupole correctors) are planned to be installed in order to correct the edge focusing effect and tune. In this report, we describe a deliberation flow about the design of the beam ducts, which are installed in the quadrupole corrector. The effects of eddy current were examined in the case of the titanium duct. The calculated results showed that the temperature rise was too much (up to over 350C) and the magnetic field in the beam duct is largely distorted. Therefore we decided to employ alumina ceramics beam ducts. The stress and displacement, which are caused by the atmospheric pressure, were estimated by simulating the realistic equipments in the beam line. It was found that there was no large stress and displacement by installing the alumina ceramics duct.
-ray imaging technologyKawachi, Naoki
Journal of the Vacuum Society of Japan, 57(2), p.37 - 44, 2014/02
Kojima, Atsushi; Hanada, Masaya; Inoue, Takashi; NB Heating Technology Group; Yamano, Yasushi*; Kobayashi, Shinichi*
Journal of the Vacuum Society of Japan, 56(12), p.502 - 506, 2013/12
Voltage holding capability of a large negative ion source for fusion application is experimentally examined, which is characterized by multiple-stage acceleration with multiple-apertures over 1000 on large-area grids of 2 m
for the multiple-beamlet accelerations. From the observation of the vacuum discharge between the grids, it was found that the aperture generated 10 times larger dark current than the flat region and initiated the vacuum discharge associated with the breakdown. As a result, it was found that the sustainable voltages were dominated by not only the surface area but also the number of the apertures. Because these effects were originated in the area effects by weak and strong electric field profiles, these results implied the surface integration of the electric field were the key parameter for the vacuum insulation.
Kamiya, Junichiro
Journal of the Vacuum Society of Japan, 56(11), p.440 - 448, 2013/11
This workshop intends to an activation of vacuum science field thorough talks of young scientists, who are concerning themselves in the vacuum technology, surface, thin films, and so on. My talk will be based on my own experiments, which are cultivated though works in J-PARC and CERN. The abstract is following. High power beam is one of the mainstreams of the particle accelerators. Characteristics of vacuum systems in accelerators are their large dimensions, existence of beam, radiation circumstances. These characteristics are not independent. And therefore in high power accelerators, there are many functions, which related to the vacuum are broad. In my talk, I intend to show the importance and appeals of the vacuum in high power accelerators through experimental results of vacuum apparatus, to which I actually related, such as a J-PARC kicker magnet, a large aperture titanium chamber, a vacuum chamber of high magnetic permeability, and a CERN collimator.
Kamiya, Junichiro; Ogiwara, Norio; Kinsho, Michikazu; Kamakura, Keita*; Hamatani, Noriaki*; Hatanaka, Kichiji*; Fukuda, Mitsuhiro*; Takahisa, Keiji*
Journal of the Vacuum Society of Japan, 56(5), p.167 - 171, 2013/05
no abstracts in English
Ogiwara, Norio; Suganuma, Kazuaki; Hikichi, Yusuke; Nishikawa, Masaaki; Yanagibashi, Toru; Kamiya, Junichiro; Kinsho, Michikazu
Journal of the Vacuum Society of Japan, 56(5), p.159 - 162, 2013/05
Ogiwara, Norio
Journal of the Vacuum Society of Japan, 56(4), p.146 - 150, 2013/04
Sukenobu, Satoru*; Masaki, Kentaro*; Ohkama, Kazuma*; Ogiwara, Norio
Journal of the Vacuum Society of Japan, 56(4), p.142 - 145, 2013/04
Kamiya, Junichiro; Ogiwara, Norio; Nishikawa, Masaaki; Hikichi, Yusuke; Yanagibashi, Toru; Suganuma, Kazuaki
Journal of the Vacuum Society of Japan, 55(4), p.156 - 159, 2012/04
It is usually difficult to reduce outgassing of a large structure inside a vacuum chamber by baking the whole chamber, which causes the large extension of the chamber and needs a lot of heater power. The solution is to rise the temperature of structure object without heating the vacuum chamber. This means to install heat source inside the chamber and increase the heat quantity to the object by inserting the heat shield between the object and the chamber. In the particle accelerator field, there are a lot of such requirements for reducing outgassing of structures inside vacuum chambers. One example is a kicker magnet, which is installed in a vacuum chamber and consists mainly of ferrite cores and aluminum electric plates. We applied the above method to the outgassing reduction of the kicker. In this article, we show outline of this in-situ bake-out method, the effects of the heat shield on the heat quantity and the result of the outgassing reduction.
Kato, Shinichi*; Kamiya, Junichiro; Yamamoto, Kazami; Yoshimoto, Masahiro; Kinsho, Michikazu
Journal of the Vacuum Society of Japan, 55(4), p.160 - 163, 2012/04
It is necessary to shield particles which are in vacuum chamber from the unexpected magnetic field to keep stable operation for accelerator. In this case, it's most efficient that the vacuum chamber has magnetic shield effect. For such a reason, we have developed the vacuum chamber with magnetic shield effect using the material of SUS430 which is magnetic material. The requirements for this chamber are not only magnetic shield effect but also low outgassing rate to use for high intensity accelerator. We measured outgassing rate of the SUS430 using small samples with differential pressure flow method, it was cleared that the SUS430 is available for vacuum chamber.
Ogiwara, Norio; Kamiya, Junichiro
Journal of the Vacuum Society of Japan, 55(4), p.152 - 155, 2012/04
Kamiya, Junichiro; Ogiwara, Norio; Hayashi, Naoki; Hotchi, Hideaki; Yoshimoto, Masahiro; Kinsho, Michikazu
Journal of the Vacuum Society of Japan, 55(3), p.100 - 103, 2012/03
It is necessary to reduce the beam loss in the high power beam accelerators. One of the reasons of the beam loss is the leakage magnetic field from the beam line magnet, which distorts the beam orbit and makes the beam hit the wall of the beam pipe. The most effective way to shield such leakage field is to cover the beam by the magnetic materials at the nearest space. We decided to apply this method to the vacuum chambers of the straight section of the J-PARC 3 GeV synchrotron, where the effect of the leakage magnetic field to the beam orbit is evident. However, there is few proven evidence of the vacuum chambers of the magnetic material. Therefore we clarify the problems in producing vacuum chambers and bellows, which satisfy the magnetic and vacuum performance. In this article, we deliver the over view of the magnetic shielding project and our approaches to the problems in producing the vacuum chambers of new material.
