Shobuda, Yoshihiro; Irie, Yoshiro*; Takayanagi, Tomohiro; Togashi, Tomohito; Yamamoto, Masanobu; Yamamoto, Kazami
Journal of Physics; Conference Series, 1067, p.062007_1 - 062007_8, 2018/10
The present four-terminal kicker at the Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) has the power-saving benefit due to the doubled excitation currents by shorting two-terminals. On the other hand, beam instabilities are excited by the kicker impedances. In this report, we describe a scheme to reduce the kicker impedances using diodes (nonlinear devices) with resistors, while retaining the benefit of the doubled kicker excitation currents.
Tamura, Fumihiko; Sugiyama, Yasuyuki*; Yoshii, Masahito*; Omori, Chihiro*; Yamamoto, Masanobu; Shimada, Taihei; Nomura, Masahiro; Hasegawa, Katsushi*; Hara, Keigo*; Furusawa, Masashi*
Journal of Physics; Conference Series, 1067, p.072030_1 - 072030_6, 2018/10
Vector RF voltage feedback control for the wideband magnetic alloy cavity of the J-PARC RCS is considered to be employed to compensate the heavy beam loading caused by high intensity proton beams. A prototype system of multiharmonic RF vector voltage control has been developed and is under testing. To characterize the system performance, full RF simulations could be performed by software like Simulink, while the software is proprietary and expensive. Also, it requires much computing power and time. We performed the simplified baseband simulations of the system in z-domain by using free software, Scilab and Python control library. It seems to be beneficial for searching the parameters that the baseband simulation can be performed quickly. In this presentation, we present the setup and results of the simulations. The simulations well reproduce the open and closed loop responses of the prototype system.
Takayanagi, Tomohiro; Ueno, Tomoaki*; Horino, Koki*
Journal of Physics; Conference Series, 1067, p.082019_1 - 082019_6, 2018/10
Yamamoto, Masanobu; Nomura, Masahiro; Shimada, Taihei; Tamura, Fumihiko; Furusawa, Masashi*; Hara, Keigo*; Hasegawa, Katsushi*; Omori, Chihiro*; Sugiyama, Yasuyuki*; Yoshii, Masahito*
Journal of Physics; Conference Series, 1067, p.052014_1 - 052014_6, 2018/10
The J-PARC RCS employs Magnetic Alloy (MA) loaded cavities. The RF power is fed by vacuum tubes in push-pull operation. We realize multi-harmonic RF driving and beam loading compensation thanks to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in multi-harmonics. An unbalance of the anode voltage swing remarkably appears at very high intensity beam acceleration. We propose a single-ended MA cavity for the RCS beam power upgrade, where no unbalance arises intrinsically.
Moriya, Katsuhiro; Kawane, Yusuke*; Miura, Akihiko; Futatsukawa, Kenta*; Miyao, Tomoaki*
Journal of Physics; Conference Series, 1067, p.072009_1 - 072009_3, 2018/09
no abstracts in English
Kamiya, Junichiro; Ogiwara, Norio*; Miura, Akihiko; Kinsho, Michikazu; Hikichi, Yusuke*
Journal of Physics; Conference Series, 1067, p.072006_1 - 072006_6, 2018/09
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 gas.
Tamura, Jun; Kondo, Yasuhiro; Morishita, Takatoshi; Ao, Hiroyuki*; Naito, Fujio*; Otani, Masashi*; Nemoto, Yasuo*
Journal of Physics; Conference Series, 1067(5), p.052009_1 - 052009_6, 2018/09
In the Japan Proton Accelerator Research Complex (J-PARC) linac, the Annular-ring Coupled Structure (ACS) cavities have been stably operating. To maintain this operation availability, we manufactured three pillbox-type RF windows for the ACS cavities in fiscal year 2015 and 2017. It is desirable to minimize the RF reflection of the RF window to prevent standing waves from exciting between the cavity and the RF window, and not to significantly change the optimized coupling factor between the cavity and the waveguide. To realize the minimization, the relative permittivities of the ceramic disks of the RF windows were evaluated by measuring the resonant frequencies of the pillbox cavity containing the ceramic disk. On the basis of the evaluated relative permittivities, the pillbox-part lengths of the RF windows were determined. The measured Voltage Standing Wave Ratios (VSWRs) of the manufactured RF windows are just about 1.08 and these are applicable for the practical use.
Miura, Akihiko; Moriya, Katsuhiro; Miyao, Tomoaki*
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.5022 - 5025, 2018/06
A wire-scanner monitor using metallic wire is reliably employed for the beam-profile measurement in the J-PARC linac. Because the loading of negative hydrogen (H) ion beam on a wire increases under high-current beam operation, we focus on using a high-durability beam profile monitors by attaching another wire material. Carbon nanotubes (CNT) are made of graphite in a cylindrical shape and have a tensile strength not less than 100 times that of steel. The electric conductivity has higher than that of metals, and hardness is endured thermally around 3000C in a vacuum circumstance. We applied the wires made from CNT to WSM and measured transverse profiles with a 3-MeV H beam. As a result, we obtained the equivalent signal levels taken by carbon wire made of polyacrylonitrile without any damage. In this paper, the signal response when the CNT is irradiated with an H beam and the result of beam profile measurement. In addition, the surface of CNT after 3-MeV beam operation was observed.
Saha, P. K.; Shobuda, Yoshihiro; Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Tamura, Fumihiko
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.620 - 623, 2018/06
Yamamoto, Kazami; Saha, P. K.
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1045 - 1047, 2018/06
The 3 GeV rapid cycling synchrotron (RCS) at the Japan Proton Accelerator Research Complex (J-PARC) provides more than 500 kW beams to the Material and Life Science Facility (MLF) and Main Ring (MR). In such a high-intensity hadron accelerator, even losing less than 0.1% of the beam can cause many problems. Such lost protons can cause serious radio-activation and accelerator component malfunctions. Therefore, we have conducted a beam study to achieve high-power operation. In addition, we have also maintained the accelerator components to enable stable operation. This paper reports the status of the J-PARC RCS over the last two years.
Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Iwamoto, Hiroki; Hasegawa, Shoichi; Maekawa, Fujio; Yoshida, Makoto*; Ishida, Taku*; Makimura, Shunsuke*; Nakamoto, Tatsushi*
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.499 - 501, 2018/06
no abstracts in English
Takahashi, Hiroki; Miura, Akihiko; Sawabe, Yuki; Yoshimoto, Masahiro; Suzuki, Takahiro*; Kawase, Masato*
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.2180 - 2182, 2018/06
The stepping motor control system used in the profile monitor and RCS collimator of J-PARC is configured by VME-based. Most of these pieces of control equipment are in use for more than 10 years. Therefore, countermeasures against aging of equipment are necessary. In addition, it is necessary to implement countermeasures against malfunction of the control system, which is thought to be caused by radiation. In 2016, a malfunction occurred in the motor control system of the RCS collimator. Taking this as a starting point, we began developing a motor control system that can ensure equipment safety even if a malfunction occurs. In this paper, we show the inference of the cause of this malfunction and present details of the developed high-safety motor control system.
Hotchi, Hideaki; Watanabe, Yasuhiro; Harada, Hiroyuki; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yoshimoto, Masahiro
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1041 - 1044, 2018/06
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio; Koseki, Tadashi; Yamamoto, Noboru; Yoshii, Masahito
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1038 - 1040, 2018/06
Yoshimoto, Masahiro; Saha, P. K.; Kato, Shinichi; Okabe, Kota; Yamamoto, Kazami; Kinsho, Michikazu
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1048 - 1050, 2018/06
The charge exchange multi-turn beam injection scheme is adopted in the J-PARC 3GeV Rapid Cycling Synchrotron Accelerator (RCS) due to achieve 1MW beam power operation. In the conventional multi-turn beam injection scheme, which is provided by only the septum and bump magnets, injecting turn numbers are limited by the beam losses at the septum. On the other hand, charge exchange multi-turn beam injection does not cause the beam losses at the septum; there is no restriction in principle on the injecting turn number. However, high residual doses are observed around the stripper foil. During the charge exchange multi-turn beam injection, not only the injecting beam but also circulating beam hit the foil, and then a large number of secondary particles, namely protons and neutrons, are generated. PHITS simulation results indicate that the secondary particles cause the high residual doses around the foil. To verify this examination, secondary particles measurement is key issue. Then, a new independent type foil introducing device is installed in the 100-deg dump beam transport line in order to construct a simple experimental system for secondary particle measurements. We plan the two experiments by using this system; one is a directly secondary particle detecting method, and the other is a radioactivation analysis method with metal sample pieces. Now, we started the study of how the identification of species and energies of the secondary particles with PHITS code. Irradiation target of Cu is adopted and irradiated proton or neutron beam with various energy range. Then radio-nuclides emitted the -ray are picked up. Moreover, the radio-nuclides, whose reaction efficiencies due to beam species or energy are different, are searched for the indicator of the secondary particles. From the simulation results, Zn is extremely suitable for a proton beam indicator, and Co and Co are also suited for a neutron and proton indicator respectively.