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Fuwa, Yasuhiro; Takayanagi, Tomohiro; Iwashita, Yoshihisa*
IEEE Transactions on Applied Superconductivity, 32(6), p.4006705_1 - 4006705_5, 2022/09
Times Cited Count：0 Percentile：0(Engineering, Electrical & Electronic)Space charge compensation technique using multipole magnetic field components has been proposed to transport high intensity beam in the J-PARC linac. In order to realize this compensation technique, a compact size permanent hybrid multi-pole magnet would be suitable. A magnet system for the simultaneous production of quadrupole and adjustable octupole components using permanent magnet materials and have manufactured a first model of the magnet systems.
beam with orifice in J-PARC front-endShibata, Takanori*; Ikegami, Kiyoshi*; Nammo, Kesao*; Liu, Y.*; Otani, Masashi*; Naito, Fujio*; Shinto, Katsuhiro; Okoshi, Kiyonori; Okabe, Kota; Kondo, Yasuhiro; et al.
JPS Conference Proceedings (Internet), 33, p.011010_1 - 011010_6, 2021/03
Together with the intensity upgrade in J-PARC Linac Front-End, improvement of RFQ transmission ratio is an important task. This RFQ transmission ratio depends strongly upon the solenoid current settings in the low energy beam transport line (LEBT). In the present study, high beam current cases (72 mA and 88 mA H beam current in LEBT) are investigated at a test-stand. Phase space distributions of the H beam particles at the RFQ entrance are measured and compared with numerical results by Particle-In-Cell simulation. As a result, it has been clarified that a 15 mm 
orifice for differential pumping of H
gas coming from the ion source plays a role as a collimator in these beam conditions. This leads to change the beam emittance and Twiss parameters at the RFQ entrance. Especially in the condition with the beam current up to 88 mA in LEBT, the beam collimation contributes to optimize the phase space distribution to the RFQ acceptance with relatively low solenoid current settings. As a higher solenoid current setting would be necessary to suppress the beam expansion due to high space charge effect, these results suggest that current-saving of the solenoids can be possible even in the higher beam intensity operations.
beam dynamics in J-PARC LEBTShibata, Takanori*; Ikegami, Kiyoshi*; Liu, Y.*; Miura, Akihiko; Naito, Fujio*; Nammo, Kesao*; Oguri, Hidetomo; Okoshi, Kiyonori; Otani, Masashi*; Shinto, Katsuhiro; et al.
Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.519 - 521, 2019/01
Transport process of negative hydrogen ion (H) in LEBT (Low Energy Beam Transport) is investigated by comparison of experimental and numerical results. A three dimensional Particle-In-Cell (PIC) particle transport model has been developed in order to take into account (i) axial magnetic field by two solenoids in J-PARC LEBT and (ii) radial electric field by space charge (SC) effect. Ratio of H beam particles inside the RFQ (Radio Frequency Quadrupole) acceptance to the total particles at the RFQ entrance is calculated for different current conditions in LEBT solenoid 1 and 2. The results are compared with RFQ transmission rate measured in the J-PARC linac commissioning. The double peak of RFQ transmission rate to the solenoid applied current seen in the measurement is explained by the calculation results. The results indicate that presence of the LEBT orifice for differential pumping plays a role as a collimator to reduce emittance at RFQ entrance.
Harada, Hiroyuki; Meigo, Shinichiro; Shirakata, Masashi*; Sato, Yoichi*; Tamura, Fumihiko; Tejima, Masaki*; Hashimoto, Yoshinori*; Igarashi, Susumu*; Koseki, Tadashi
JPS Conference Proceedings (Internet), 8, p.012010_1 - 012010_6, 2015/09
The J-PARC 3-50BT line is the beam transport line from 3-GeV rapid-cycling synchrotron (RCS) to 50-GeV main ring (MR). The RCS is the high-intensity proton accelerator, where designed beam power is 1 MW, and has the complex source of space charge effect, etc. Therefore, the uncontrolled emittance growth and beam halo increase nonlinearly with the increasing the beam power. Additionally, the physical aperture of MR with 81 
mm mrad is smaller than that of RCS with 486 mm mrad. Therefore, the 3-50BT line has the collimators in order to remove the tail or halo of the extracted beam from the RCS. The designed collimator aperture is 54 mm mrad. It is required to measure and optimize the optics parameters in the collimator area for taking full advantage of the beam collimation. Especially, it is very important to make the dispersion functions free in the collimator area and optimize the beta function. This paper will introduce the method of optics measurement and report the result of the measurement and optimization based on the simulation.
Tomisawa, Tetsuo; Kishiro, Junichi; Igarashi, Zenei*; Lee, S.*; Hiroki, Fumio
Proceedings of 28th Linear Accelerator Meeting in Japan, p.428 - 430, 2003/08
It is an important factor whether to have a beam loss held how, and the part of the beam diagnosis is important with the accurate beam transport, the occurrence of the high quality beam to accelerate a high intensity proton beam to handle with J-PARC linac accelerator safely. It responds to the purpose, and the beam monitor used for this beam diagnosis has it variously. There are an electric current monitor, a phase monitor, a beam position monitor, a profile monitor, a beam size monitor, a screen monitor, a beam loss monitor, and so on. Report it about these beam monitors in the present condition.
Meigo, Shinichiro
JAERI-Tech 2000-088, 32 Pages, 2001/02
no abstracts in English
Agematsu, Takashi; Arakawa, Kazuo; *
Cyclotrons and Their Applications 1998 (Cyclotrons'98), p.232 - 235, 1998/00
no abstracts in English
Oshita, Hironori; Toyama, Shinichi; Hirano, Koichiro; Konashi, Kenji; Sasao, Nobuyuki; Sato, Isamu
PNC TN8410 91-048, 92 Pages, 1991/02
None
Yoshikawa, Hiroshi; Nakamura, Naoki*; ; ; ; ; Yokomizo, Hideaki
Proc. of the 8th Symp. on Accelerator Science and Technology, p.304 - 305, 1991/00
no abstracts in English
Yokota, Wataru; Ishibori, Ikuo; Okumura, Susumu; Agematsu, Takashi; Fukuda, Mitsuhiro; Nara, Takayuki; Kamiya, Tomihiro; Nakamura, Yoshiteru; Arakawa, Kazuo; Tachikawa, T.*; et al.
Proc. of the 8th Symp. on Accelerator Science and Technology, p.70 - 72, 1991/00
no abstracts in English
Fuwa, Yasuhiro; Moriya, Katsuhiro; Takayanagi, Tomohiro
no journal, ,
In the high-intensity operation of the J-PARC Linac, it is necessary to suppress the beam loss caused by the emittance growth and the beam halo formation due to the space charge in the low-energy region. As a method to suppress the space charge effect, it has been proposed to cancel the effect of higher-order components of the space charge effect by using higher-order multipole fields such as octupole fields. In this presentation, we will report the characteristics of the multipole magnets fabricated for the MEBT1 of the J-PARC Linac and simulation results on the suppression of the space charge effect based on the magnetic field distribution generated by the fabricated magnet.
