Thermal desorption characteristics of several charge stripper carbon films for J-PARC RCS

Kamiya, Junichiro; Kinsho, Michikazu; Yamazaki, Yoshio; Yoshimoto, Masahiro; Yanagibashi, Toru*

Journal of the Vacuum Society of Japan, 60(12), p.484 - 489, 2017/12

https://doi.org/10.3131/jvsj2.60.484

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.

Detection of electron beam with a gas sheet

Ogiwara, Norio; Hikichi, Yusuke; Kamiya, Junichiro; Kinsho, Michikazu

Journal of the Vacuum Society of Japan, 59(4), p.79 - 82, 2016/04

https://doi.org/10.3131/jvsj2.59.79

Monte Carlo simulations of the beam effect for the emitted molecules from the rotating disks

Ogiwara, Norio

Journal of the Vacuum Society of Japan, 58(5), p.168 - 172, 2015/05

https://doi.org/10.3131/jvsj2.58.168

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.

Study of oxide film with the hard X-ray photoelectron spectroscopy

Kobata, Masaaki; Kobayashi, Keisuke*

Journal of the Vacuum Society of Japan, 58(2), p.43 - 49, 2015/02

https://doi.org/10.3131/jvsj2.58.43

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.

Recent developments in plant science involving use of -ray imaging technology

Kawachi, Naoki

Journal of the Vacuum Society of Japan, 57(2), p.37 - 44, 2014/02

https://doi.org/10.3131/jvsj2.57.37

Challenges to the vacuum system in high intensity accelerators

Kamiya, Junichiro

Journal of the Vacuum Society of Japan, 56(11), p.440 - 448, 2013/11

https://doi.org/10.3131/jvsj2.56.440

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.

Titanium alloy as low activation vacuum material

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

https://doi.org/10.3131/jvsj2.56.167

no abstracts in English

Monte Carlo simulation of gas-sheet targets generated by narrow slits

Ogiwara, Norio

Journal of the Vacuum Society of Japan, 56(4), p.146 - 150, 2013/04

https://doi.org/10.3131/jvsj2.56.146

Development of an in-situ bake-out method for outgassing reduction of kicker ferrite cores

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

https://doi.org/10.3131/jvsj2.55.156

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.

Magnetic field shielding by vacuum chambers of magnetic material for beam loss reduction

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

https://doi.org/10.3131/jvsj2.55.100

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.