Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Performance and status of the J-PARC accelerators

Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio*; Koseki, Tadashi*; Yamamoto, Noboru*; Hori, Yoichiro*

Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2290 - 2293, 2017/06

https://doi.org/10.18429/JACoW-IPAC2017-TUPVA090

The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). We have taken many hardware upgrades such as front end replacement and energy upgrade at the linac, vacuum improvement, collimator upgrade, etc. The beam powers for the neutrino experiment and hadron experiment from the MR have been steadily increased by tuning and reducing beam losses. The designed 1 MW equivalent beam was demonstrated and user program was performed at 500 kW from the RCS to the neutron and muon experiments. We have experienced many failures and troubles, however, to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.

Measurement of ion species in high current ECR H/D ion source for IFMIF (International Fusion Materials Irradiation Facility)

Shinto, Katsuhiro; Sene, F.*; Ayala, J.-M.*; Bolzon, B.*; Chauvin, N.*; Gobin, R.*; Ichimiya, Ryo; Ihara, Akira; Ikeda, Yukiharu; Kasugai, Atsushi; et al.

Review of Scientific Instruments, 87(2), p.02A727_1 - 02A727_3, 2016/02

https://doi.org/10.1063/1.4933342

Positive and negative ion sources for magnetic fusion

Hemsworth, R. S.*; Inoue, Takashi

IEEE Transactions on Plasma Science, 33(6), p.1799 - 1813, 2005/12

https://doi.org/10.1109/TPS.2005.860090

The positive or negative ion sources which form the primary components of neutral beam injection systems used in magnetic fusion have to meet simultaneously several demanding requirements. This paper describes the underlying physics of modern positive ion sources, which provide the required high proton fraction (90%) and high current density (2 kA/m) at a low source pressure (0.4 Pa) with a high electrical efficiency and uniformity across the accelerator grids. The development of negative ion sources, which are required if high energy neutral beams are to be produced, is explained. The paper reports that negative ion sources have achieved many of the parameters required of sources for the neutral beam injectors of future fusion devices and reactors, 200 A/m of D at low pressure, 0.3 Pa, with low co-extracted electron content. The development needed to meet all the requiremens of future systems is briefly discussed.

Damage diagnostic of localized impact erosion by measuring acoustic vibration

Futakawa, Masatoshi; Naoe, Takashi*; Kogawa, Hiroyuki; Ikeda, Yujiro

Journal of Nuclear Science and Technology, 41(11), p.1059 - 1064, 2004/11

https://doi.org/10.3327/jnst.41.1059

High power spallation targets for neutron sources are developing in the world. Mercury target will be installed at the material and life science facility in J-PARC, which will promote innovative science. The mercury target is subject to the pressure wave caused by the proton bombarding mercury. The pressure wave propagation induces the cavitation in mercury that imposes localized impact damage on the target vessel. The impact erosion is a critical issue to decide the lifetime of the target. The electric Magnetic Impact Testing Machine, MIMTM, was developed to produce the localized impact erosion damage and evaluate the damage formation. Acoustic vibration measurement was carried out to investigate the correlation between damage and acoustic vibration. It was confirmed that the acoustic vibration is useful to predict the damage due to the localized impact erosion and to diagnose the structural integrity.

High proton ratio plasma production in a small negative ion source

Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi*; Watanabe, Kazuhiro; Imai, Tsuyoshi

Review of Scientific Instruments, 75(5), p.1764 - 1766, 2004/05

https://doi.org/10.1063/1.1695623

Negative ion beams of high current density are required for accelerator and fusion. The H source utilizes surface production that produces H from H or H. And hence, high proto yield ion source is required. Generally, a large volume plasma generator with strong plasma confinement is suitable to achieve high proton yield. On the contrary, production of high proton ratio plasma is not easy in small sources. However, in a small source (3.5 liter), high current H beam of 800 A/m was obtained. In this research, the proton ratio was investigated experimentally and analytically in a small source (1.4 liter). The measured proton ratio increased form 40% to 90% by applying the magnetic filter. From the numerical analysis, the proton ratio is low as 40% in the driver region. However, with the magnetic filter, flow of primary electrons is restrained, resulting in suppression of H production at the extraction region. In addition, molecular ions are easily destroyed by thermal electrons in the filter region. Thus the proton ratio is enhanced by the magnetic field in the small sources.

Production mechanism of high proton ratio plasma in a hydrogen arc discharge ion source

Morishita, Takatoshi; Inoue, Takashi; Iga, Takashi*; Watanabe, Kazuhiro; Kashiwagi, Mieko; Shimizu, Takashi; Taniguchi, Masaki; Hanada, Masaya; Imai, Tsuyoshi

JAERI-Tech 2003-007, 16 Pages, 2003/03

JAERI-Tech-2003-007.pdf:1.28MB

Recently the ion source for IFMIF (International Fusion Material Irradiation facility) achieved positive ion beams of 120 mA with the proton ratio of 90% by applying magnetic filter even in a small ion source. The mechanism of a high proton ration plasma production in such a small ion source has not been studied. Molecular ions are destroyed and the proton is produced from the dissociation of molecular ions in the filter region. Thus the proton yield is enhanced even in the small volume discharge. Using the same numerical method, the plasma production was calculated for the large ion source. The high proton ratio can be easily obtained, where the contribution of proton production by the ionization of H becomes high. From the negative ion production point of view, the negative ion beam current was numerically evaluated. The high atom flux to the plasma grid generates the large amount of negative ions rather than that by the positive ions in Cs-seeded large ion sources.

Longitudinal beam dynamincs on 3 GeV PS in JAERI-KEK joint project

Yamamoto, Masanobu; Tamura, Fumihiko; Ezura, Eiji*; Hashimoto, Yoshinori*; Mori, Yoshiharu*; Omori, Chihiro*; Schnase, A.*; Takagi, Akira*; Uesugi, Tomonori*; Yoshii, Masahito*

Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.1073 - 1075, 2002/00

Longitudinal beam emittance should be controlled to alleviate space charge effects by rf manipulations at 3 GeV proton synchrotrons in JAERI-KEK Joint High Intensity Proton Accelerator Project. At injection, bunching factor of 0.4 will be achived by controlled longitudinal beam painting and multiplying 2nd higher harmonics. Furthermore, heavy beam loading is a severe problem, and it should be compensated by feedforward method for stable acceleration. About these themes, the scenario will be described with particle tracking simulations.

HETC-3STEP calculations of proton induced nuclide production cross sections at incident energies between 20 MeV and 5 GeV

Takada, Hiroshi; Yoshizawa, Nobuaki*;

JAERI-Research 96-040, 91 Pages, 1996/08

JAERI-Research-96-040.pdf:2.2MB

no abstracts in English

Design of a high brightness ion source for the Basic Technology Accelerator(BTA)

Okumura, Yoshikazu; Watanabe, Kazuhiro

JAERI-M 92-024, 23 Pages, 1992/03

JAERI-M-92-024.pdf:0.87MB

no abstracts in English