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Journal Articles

Evaluation of 2-D transverse beam profile monitor using gas sheet at J-PARC LINAC

Kamiya, Junichiro; Okabe, Kota; Kinsho, Michikazu; Moriya, Katsuhiro; Yamada, Ippei; Ogiwara, Norio*; Hikichi, Yusuke*; Wada, K.*

Journal of Physics; Conference Series, 1350, p.012149_1 - 012149_6, 2019/12

 Times Cited Count:2 Percentile:84.98

To obtain a getter effect to titanium vacuum duct surface, the method to remove the oxide on the surface by sputtering with ionized molecules has been developed. In the method, a sheet-shaped gas distribution with a uniform and high density is generated through a narrow slit by a small amount of gas. In this report, the gas density distribution was calculated by the Monte Carlo simulation code. As a result, it was found that a gas injection from both directions was effective to generate uniform density distribution. Furthermore, the gas injection method was applied to a non-destructive beam profile monitor, that detects ions generated by the interaction between gas molecules and beam. In this monitor, dependence of the beam profile on the injected gas amount was measured. A small amount of injected gas was found to be ideal for the beam profile measurements in the unsaturated and a high S/N ratio region.

Journal Articles

Turbomolecular pump as main pump in a high-power proton accelerator vacuum system

Kamiya, Junichiro; Kinsho, Michikazu; Ogiwara, Norio*; Sakurai, Mitsuru*; Mabuchi, Takuya*; Wada, Kaoru*

Vacuum and Surface Science, 62(8), p.476 - 485, 2019/08

J-PARC 3GeV rapid cycling synchrotron (RCS) is one of the highest beam power proton accelerators. Challenges for achieving low pressure region in ultra-high vacuum (UHV) in the beam line are the large outgassing source. We focused turbo molecular pumps (TMP) as maing pump because it can evacuate the continuous and additional outgassing with large pumping speed in wide pressure range. It is also possible to evacuate from low vacuum to UHV with only a few hours by using TMP, which ensures users' experimental time after vacuum device maintenance. During more than 10 years operation of the vacuum system, many experiences have been accumulated about the usage of TMP in RCS. In this presentation, we discussed about validity of TMP as main pump in high power proton beam accelerator by showing the performance of the beam line pressure during the beam operation. Further, in anticipation of upgrade higher beam power more than 1 MW, validity of a combination of TMP and NEG pump will be mentioned.

Journal Articles

Development of a gas distribution measuring system for 2-D beam profile monitor

Yamada, Ippei; Ogiwara, Norio*; Hikichi, Yusuke*; Kamiya, Junichiro; Kinsho, Michikazu

Vacuum and Surface Science, 62(7), p.400 - 405, 2019/07

no abstracts in English

Journal Articles

Development of a gas distribution measuring system for gas sheet beam profile monitor

Yamada, Ippei; Ogiwara, Norio*; Hikichi, Yusuke*; Kamiya, Junichiro; Kinsho, Michikazu

Proceedings of 10th International Particle Accelerator Conference (IPAC '19) (Internet), p.2567 - 2570, 2019/06

no abstracts in English

Journal Articles

Non-destructive 2-D beam profile monitor using gas sheet in J-PARC LINAC

Kamiya, Junichiro; Ogiwara, Norio*; Miura, Akihiko; Kinsho, Michikazu; Hikichi, Yusuke*

Journal of Physics; Conference Series, 1067, p.072006_1 - 072006_6, 2018/09

 Times Cited Count:2 Percentile:77.73

A beam profile monitor using interaction between the beam and the gas molecules distributed in sheet shape has been developed. Ions or luminescence generated by passing the beam through the gas sheet has the information of cross-section shape of the beam. The gas sheet beam monitor will become a useful tool to measure the profile of high power beams because it has no breakable element such as wires. Furthermore, 2-D beam profile can be obtaine at a certain position of beam line. We applied the gas-sheet based beam profile monitor to J-PARC LINAC, where the negative hydrogen atoms are accelerated to the energy of 400 MeV. The vacuum system was carefully designed not to make an unacceptable pressure rise in nearby cavities when the gas was injected. The clear image of the beam profile was successfully obtained by detecting the ionized N$$_{2}$$ gas.

Journal Articles

Development of gas distribution measurement system for a two-dimensional beam profile monitor with a sheet-shaped gas

Yamada, Ippei; Ogiwara, Norio*; Hikichi, Yusuke*; Kamiya, Junichiro; Kinsho, Michikazu

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.88 - 92, 2018/08

no abstracts in English

Journal Articles

Conductance of a long rectangular channel; Pressure dependence

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

Journal Articles

Development of a gas-sheet target for a non-destructive profile monitor

Ogiwara, Norio; Hikichi, Yusuke*; Kamiya, Junichiro; Yamamoto, Kazami; Kinsho, Michikazu

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.563 - 567, 2017/12

Journal Articles

Vacuum improvement of kicker magnet area in J-PARC 3 GeV synchrotron

Kamiya, Junichiro; Yanagibashi, Toru; Ogiwara, Norio; Kinsho, Michikazu

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1193 - 1196, 2016/11

In this study, we propose a new in situ 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 thermal expansion of the chamber. By simply installing the heater and thermal radiation shield plates between the kicker magnet and the chamber wall, most of the heat flux from the heater directs towards the kicker magnet. 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. The outgassing rage was reduced to one tenth comparing to the case without bake out.

Journal Articles

A Non-destructive profile monitor using a gas sheet

Ogiwara, Norio; Hikichi, Yusuke; Namekawa, Yuya; Kamiya, Junichiro; Kinsho, Michikazu; Hatanaka, Kichiji*; Shima, Tatsushi*; Fukuda, Mitsuhiro*

Proceedings of 7th International Particle Accelerator Conference (IPAC '16) (Internet), p.2102 - 2104, 2016/06

Journal Articles

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

Journal Articles

${{it In situ}}$ baking method for degassing of a kicker magnet in accelerator beam line

Kamiya, 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:1 Percentile:6.36(Materials Science, Coatings & Films)

In this study, we propose a new ${{it in situ}}$ 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.

Journal Articles

Degassing of kicker magnet by in-situ bake-out method

Kamiya, Junichiro; Ogiwara, Norio; Hikichi, Yusuke; Kinsho, Michikazu; Miki, Nobuharu*; Yanagibashi, Toru*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2911 - 2913, 2015/06

New method of in-situ degassing of the kicker magnet in the beam line has been developed. The heater and heat shielding panels are installed in the vacuum chamber in this method. The heater was designed considering the maintainability. The graphite was selected as the heater and the high melting point metals were used as the reflectors just near the heater. The thermal analysis and the temperature measurement with the designed heater was performed. The ideal temperature distribution for the kicker degassing was obtained. The outgassing of the graphite during rising the temperature was measured. The result showed that the outgassing was extremely suppressed by the first heating. This means the outgassing of the graphite heater was negligible as long as it is used in the beam line without exposure to the air.

Journal Articles

Titanium alloy as a potential low radioactivation vacuum material

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:2 Percentile:11.36(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.

Journal Articles

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

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 $$r$$$$omega$$ ($$r$$: distance from the rotating axis and $$omega$$: 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 $$eta$$ $$equiv$$ $$r$$ $$_{1}$$$$omega$$/ $$<$$$$nu$$$$>$$ ($$r$$$$_{1}$$: radius of the disk and $$<$$$$nu$$$$>$$: 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 $$eta$$ less than 2, where the rotating vector is specified to be oriented to zenith.

Journal Articles

In situ degassing of the kicker magnet in J-PARC RCS

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$$^{circ}$$C, while keeping the temperature rise of the vacuum chamber less than 30$$^{circ}$$C 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.

Journal Articles

Beam loss reduction by magnetic shielding using beam pipes and bellows of soft magnetic materials

Kamiya, Junichiro; Ogiwara, Norio; Hotchi, Hideaki; Hayashi, Naoki; Kinsho, Michikazu

Nuclear Instruments and Methods in Physics Research A, 763, p.329 - 339, 2014/11

 Times Cited Count:3 Percentile:30.04(Instruments & Instrumentation)

One of the main sources of beam loss in high power accelerators is unwanted stray magnetic fields from magnets near the beam line, which can distort the beam orbit. The most effective way to shield such magnetic fields is to perfectly surround the beam region without any gaps with a soft magnetic high permeability material. This leads to the manufacture of vacuum chambers (beam pipes and bellows) with soft magnetic materials. Using this heat treatment, the ratio of the integrated magnetic flux density along the beam orbit between the inside and outside of the beam pipe and bellows became small enough to suppress beam orbit distortion. The outgassing rate of the materials with this heat treatment was reduced by one order magnitude compared to that without heat treatment. By installing the beam pipes and bellows of soft magnetic materials as part of the Japan Proton Accelerator Research Complex 3 GeV rapid cycling synchrotron beam line, the closed orbit distortion was reduced by more than 80%. In addition, a 95.5% beam survival ratio was achieved by this COD improvement.

Journal Articles

Bellows with a new RF shield made of metal braid for high intensity proton accelerators

Ogiwara, Norio; Kamiya, Junichiro; Shobuda, Yoshihiro; Kinsho, Michikazu; Koizumi, Oji*

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3321 - 3323, 2014/07

Journal Articles

Design consideration of beam duct for quadrupole correctors in J-PARC RCS

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 350$$^{circ}$$C) 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.

Journal Articles

Development of a turbo-molecular pump with a magnetic shield function

Ogiwara, Norio; Yanagibashi, Toru; Hikichi, Yusuke; Nishikawa, Masaaki; Kamiya, Junichiro; Wada, Kaoru*

Vacuum, 98, p.18 - 21, 2013/12

 Times Cited Count:6 Percentile:30.5(Materials Science, Multidisciplinary)

108 (Records 1-20 displayed on this page)