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Shibata, Takanori*; Shinto, Katsuhiro; Wada, Motoi*; Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*
AIP Conference Proceedings 2373, p.050002_1 - 050002_9, 2021/08
Oscillation of emittance and Twiss parameters in the negative ion beam from the J-PARC 2-MHz RF ion source is measured by applications of a double-slit emittance monitor located at the RFQ (Radio Frequency Quadrupole) entrance. The emittance monitor is equipped with a newly-developed 60 MS/s data acquisition system, so that beam current oscillation in a few MHz can be observed with enough time resolution. From the measurement, it is shown that the beam phase space consists of (1) a DC component in the beam core, (2) a 2-MHz oscillating component which takes place both in the beam core and the halo and (3) a doubled RF frequency (4 MHz) oscillation which slightly exists in the beam halo. The major component is the 2-MHz component, which resultantly decides the beam emittance oscillation frequency. A typical value of the beam emittance in the present experiment is 0.34 
mm-mrad, while the amplitude of the 2 MHz oscillation is around 0.04 mm-mrad. The results indicate that the high-frequency oscillation component occupying about ten-percent of the beam from the RF source travels a few meters passing through a magnetic lens focusing system.
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.
Miura, Akihiko; Liu, Y.*; Maruta, Tomofumi*; Miyao, Tomoaki*
Proceedings of 5th International Beam Instrumentation Conference (IBIC 2016) (Internet), p.150 - 153, 2017/03
no abstracts in English
Yokota, Wataru; Yuri, Yosuke; Watanabe, Shinichi*; Oshiro, Yukimitsu*; Kubono, Shigeru*
JAEA-Technology 2016-005, 21 Pages, 2016/03
JAEA-Technology-2016-005.pdf:2.24MB
The Center of Nuclear Science (CNS) of Tokyo University conducts the research on nuclear physics using CNS Radio-Isotope Beam Separator (CRIB) installed at the RIKEN AVF cyclotron. Takasaki Advanced Radiation Research Institute, JAEA has an AVF cyclotron of similar scale and is developing a technology to form a large-area uniform beam by an octupole magnetic field for the research on materials science. They carried out an R&D to increase the cyclotron beam intensity at a target under joint research. The nonlinear beam optics was designed to form a usual cyclotron beam having a large transverse tail into a small-sized tailless distribution so that the beam passes the gas target orifice (6 mm in diameter) of CRIB without a loss. As a result of particle tracking simulations based on the measured beam emittance, it has been found that an octupole magnetic field is effective in tail-folding and a 10-mm-diameter beam can be formed with two octupole magnets added in the present beam line. It has been also found that additional magnets need to be installed and the beam emittance should be reduced for the objective beam size of 6 mm. Moreover, the objective may be attained if the beam path length and configuration of the magnetic lens system are freely chosen.
Kotaki, Hideyuki; Masuda, Shinichi; Kando, Masaki; Koga, J. K.; Nakajima, Kazuhisa
Physics of Plasmas, 11(6), p.3296 - 3302, 2004/06
Times Cited Count：100 Percentile：93.56(Physics, Fluids & Plasmas)no abstracts in English
Hajima, Ryoichi
Dai-14-Kai Kasokuki Kagaku Kenkyu Happyokai Hokokushu, p.401 - 403, 2003/11
We propose a novel approach to the analysis of the coherent synchrotron radiation (CSR) effect on beam dynamics in energy-recovery linacs (ERL). Since an ERL return-arc consists of a large number of dipole and quadrupole magnets, it is not a practical way to search an optimum design by time-consuming particle simulations. We show that a first-order transfer matrix can be applied to calculate the emittance growth due to the CSR in the linear regime, weak CSR limit. The optimum design of ERL arcs such as triple-bend achromat lattice is easily obtained by matrix calculation. As an example, optimization of a 3GeV ERL arc is presented.
Chiba, Atsuya; Ishii, Yasuyuki; Tajima, Satoshi
JAERI-Review 2003-033, TIARA Annual Report 2002, p.327 - 329, 2003/11
no abstracts in English
Chiba, Atsuya; Ishii, Yasuyuki; Tajima, Satoshi
Dai-15-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.74 - 76, 2003/03
no abstracts in English
Shimooka, Takashi; Oguri, Hidetomo; Namekawa, Yuya*; Tomisawa, Tetsuo; Okumura, Yoshikazu; Hasegawa, Kazuo
JAERI-Tech 2002-038, 30 Pages, 2002/03
JAERI-Tech-2002-038.pdf:1.74MB
The high intensity proton accelerator facility project which is conducted jointly by JAERI and KEK is to use the secondary particles produced by nuclear spallation for various science studies. A negative hydrogen ion beam source for the accelerator is required to extract a peak beam current of more than 60 mA with a duty factor of 2.5 %. In addition, the ions should be negatively charged in order to improve the capture efficiency of the beam injected into a synchrotron. At JAERI, a negative ion source for the project has been developed with various technologies based on the large negative ion source for the nuclear fusion application. The negative ion beam current and the rms normalized emittance of 72 mA and 0.15 mm.mrad were achieved in the cesium seeded operation, respectively. A waveform of the pulsed beam current was sensitive to the operation gas flow rate, and became to have a good flatness at about 16 SCCM. These results show that the basic performance of the ion source satisfies the requirement of the ion source for the project.
Hanashima, Susumu
JAERI-Conf 2000-019, P. 109, 2001/02
no abstracts in English
Hasegawa, Kazuo; Ouchi, Nobuo; Mukugi, Ken*
KEK Proceedings 2000-23, p.31 - 33, 2001/02
no abstracts in English
Nishimori, Nobuyuki; Nagai, Ryoji; Hajima, Ryoichi; Shizuma, Toshiyuki; Minehara, Eisuke
Proceedings of 25th Linear Accelerator Meeting in Japan, p.71 - 73, 2000/07
no abstracts in English
Morimoto, Iwao; Kishiro, Junichi*; Takayama, Ken*; Zheng, X.; Maebara, Sunao; Shiho, Makoto
JAERI-Research 2000-008, p.59 - 0, 2000/02
JAERI-Research-2000-008.pdf:3.83MB
no abstracts in English
Hasegawa, Kazuo; Mizumoto, Motoharu; Ouchi, Nobuo; Noguchi, Shuichi*
KEK Proceedings 99-25, p.28 - 32, 2000/02
no abstracts in English
Maebara, Sunao; Morimoto, Iwao*; Zheng, X.*; Kishiro, Junichi*; Takayama, Ken*; Horioka, Kazuhiko*; Kawasaki, Sunao*; Ishizuka, Hiroshi*; Shiho, Makoto
Proceedings of 13th International Conference on High-Power Particle Beams (BEAMS 2000) (CD-ROM), 4 Pages, 2000/00
no abstracts in English
Hajima, Ryoichi; Shizuma, Toshiyuki; Minehara, Eisuke
Proceedings of 7th European Particle Accelerator Conference (EPAC 2000) (CD-ROM), p.1033 - 1035, 2000/00
no abstracts in English
Hasegawa, Kazuo; Mizumoto, Motoharu; Ouchi, Nobuo; Honda, Yoichiro*; Ino, H.*
Journal of Nuclear Science and Technology, 36(5), p.451 - 458, 1999/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Kando, Masaki; Kotaki, Hideyuki; Dewa, Hidenori; Kondo, Shuji; Yoshii, Koji*; Ueda, Toru*; Watanabe, Takahiro*; Uesaka, Mitsuru*; Sakai, Fumio*; Ogata, Atsushi*; et al.
Proceedings of 24th Linear Accelerator Meeting in Japan, p.128 - 130, 1999/00
no abstracts in English
Hasegawa, Kazuo; Mizumoto, Motoharu; Ouchi, Nobuo; Honda, Yoichiro*; Ino, H.*
Proceedings of 6th European Particle Accelerator Conference (EPAC98) (CD-ROM), 2 Pages, 1998/06
no abstracts in English
Wang, Y.
PNC TN9410 98-017, 21 Pages, 1998/02
"Injector Test (1) of PNC High Power Electron Linac" was mentioned in last year report. 100mA beam with pulse length 20
s repetition rate 1Hz and 50mA beam with pulse 1ms 0.5 Hz had been accelerated to 3.0 Mev successfully. The chopper and prebuncher system had not been used in that test. Now this report put emphases on the chopper and prebuncher systems tests. A good energy spectrum had been achieved using the chopper and prebuncher systems. And 100mA beam current with pulse length 3ms and repetition rate 0.1Hz was accelerated to 3.0 MeV.
