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Journal Articles

Fast fault recovery scenarios for the JAEA-ADS linac

Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Nakano, Keita; Takei, Hayanori; Maekawa, Fujio; Meigo, Shinichiro

Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.61 - 65, 2021/10

Japan Atomic Energy Agency (JAEA) is designing a 30 MW CW superconducting proton linac as a major component for the accelerator-driven subcritical system (ADS) project. The main challenge of the linac operation is the high reliability required to suppress thermal stress in the subcritical reactor. To this end, we implemented fault compensation schemes to enable a fast beam recovery; consequently, reducing the beam trip duration. This work presents strategies to increase the fault-tolerance capacity of the JAEA-ADS linac.

Journal Articles

Design of the MEBT for the JAEA-ADS Project

Yee-Rendon, B.; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Tamura, Jun

Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.790 - 792, 2021/08

The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.

Journal Articles

Present status of the R&D of the superconducting linac for the JAEA-ADS

Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Hasegawa, Kazuo; Maekawa, Fujio; Meigo, Shinichiro; Oguri, Hidetomo

JPS Conference Proceedings (Internet), 33, p.011043_1 - 011043_5, 2021/03

The Japan Atomic Energy Agency (JAEA) has been working in the research and development of an Accelerator Driven Subcritical System (ADS) for the transmutation of nuclear waste. The ADS proposed by JAEA consists of a CW proton linac of 30 MW coupling with a subcritical core reactor. The accelerator will be operated with a beam current of 20 mA. Normal conducting Radio-Frequency Cavities (NRFC) and Superconducting Radio-Frequency Cavities (SRFC) will be used to achieve final energy of 1.5 GeV, and the SRFC will be employed for the main part of the acceleration: from 2 MeV to 1.5 GeV. In the first stage of the accelerator development, the focus was the design and optimization of the SRFC models and the beam optics. For the SRFC sections, the acceleration will be done by using Half Wave Resonators (HWR), Single Spokes (SS), and Elliptical cavities (Ellip) operating with a frequency of 162, 324, and 648 MHz, respectively. The beam optics were optimized satisfying the equipartitioning condition to control the emittance growth, which helped to reduce the beam halos and the beam loss.

Journal Articles

Error studies for the JAEA-ADS linac

Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Oguri, Hidetomo

Proceedings of 17th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.33 - 37, 2020/09

Japan Atomic Energy Agency (JAEA)- Accelerator Driven System (ADS) linac consists of a CW proton accelerator with a beam current of 20 mA driven with the energy of 1.5 GeV. Most of the beam acceleration is achieved by using superconducting cavities to obtain high acceleration efficiency at CW mode. The main superconducting linac is composed of five families of cavities (Half Wave resonators, Spokes resonators, and Elliptical cavities) with theirs respectively magnets. Due to the large beam power in the linac of 30 MW and the high reliability required for the ADS project, a robust beam optic designed is necessary to have a stable beam operation and control the beam loss power. The JAEA-ADS linac is composed of several sections and components; thus, the misalignment of these elements together with field errors enhance the beam loss rate and compromises the safety of the linac. To this end, an error linac campaign was launched to estimate the error tolerance of the components and implement a correction scheme to reduce the beam loss power around the linac.

Journal Articles

Beam optics design of the superconducting region of the JAEA ADS

Yee-Rendon, B.; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Tamura, Jun

Journal of Physics; Conference Series, 1350(1), p.012120_1 - 012120_5, 2019/12

Journal Articles

Recent progress of J-PARC RCS beam commissioning; Efforts for realizing a high-intensity low-emittance beam

Hotchi, Hideaki; Harada, Hiroyuki; Kato, Shinichi; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; Watanabe, Yasuhiro; Yoshimoto, Masahiro

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.95 - 99, 2017/12

no abstracts in English

Journal Articles

Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kato, Shinichi; Kinsho, Michikazu; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Tani, Norio; et al.

Physical Review Accelerators and Beams (Internet), 20(6), p.060402_1 - 060402_25, 2017/06

 Times Cited Count:17 Percentile:87.54(Physics, Nuclear)

The 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) is the world's highest class of high-power pulsed proton driver, aiming for an output beam power of 1 MW. The most important issues in realizing such a high-power beam operation are to control and minimize beam loss for maintaining machine activations within permissible levels. In RCS, numerical simulation was successfully utilized along with experimental approaches to isolate the mechanism of beam loss and find its solution. By iteratively performing actual beam experiments and numerical simulations, and also by several hardware improvements, we have recently established a 1-MW beam operation with very low fractional beam loss of a couple of 10$$^{-3}$$. In this paper, our recent efforts toward realizing such a low-loss high-intensity beam acceleration are presented.

Journal Articles

Deflector design for spin rotator in muon linear accelerator

Artikova, S.; Kondo, Yasuhiro; Mibe, Tsutomu*; Otani, Masashi*

Proceedings of 28th International Linear Accelerator Conference (LINAC 2016) (Internet), p.830 - 832, 2017/05

Journal Articles

The Status of optics design and beam dynamics study in J-PARC RCS

Noda, Fumiaki*; Hotchi, Hideaki; Saha, P. K.; Shobuda, Yoshihiro; Yamamoto, Kazami; Hayashi, Naoki; Kishiro, Junichi; Machida, Shinji*; Molodojentsev, A. Y.*

Proceedings of 2005 Particle Accelerator Conference (PAC '05) (CD-ROM), p.2759 - 2761, 2005/00

no abstracts in English

Journal Articles

Photoemission study of the translational energy induced oxidation processes on Cu(111)

Moritani, Kosuke; Okada, Michio*; Sato, Seiichi*; Goto, Seishiro*; Kasai, Toshio*; Yoshigoe, Akitaka; Teraoka, Yuden

Journal of Vacuum Science and Technology A, 22(4), p.1625 - 1630, 2004/08

 Times Cited Count:20 Percentile:61.22(Materials Science, Coatings & Films)

We studied the oxidation of Cu{111} surface with a hyperthermal O$$_{2}$$ molecular beam (HOMB) using X-ray photoemission spectroscopy (XPS) in conjunction with a synchrotron radiation (SR) source. The efficiency of oxidation with 0.6-eV-HOMB is higher thab that with 2.3-eV-HOMB under $$theta$$ $$leq$$ 0.5ML. Ont the other hand, further oxidation occurs rather inefficiency under $$theta$$ $$geq$$ 0.5ML. In this region, efficiency of oxidation with 2.3-eV-HOMB is higher than 0.6-eV-HOMB. We found that such slow oxidation process of Cu can be interpreted in terms of a collision-induced-adsorption mechanism. These results suggest that we can control the oxidation process of Cu by using HOMB.

Journal Articles

SiO mass spectrometry and Si-2p photoemission spectroscopy for the study of oxidation reaction dynamics of Si(001) surface by supersonic O$$_{2}$$ molecular beams under 1000 K

Teraoka, Yuden; Yoshigoe, Akitaka; Moritani, Kosuke

Japanese Journal of Applied Physics, Part 1, 42(7B), p.4671 - 4675, 2003/07

 Times Cited Count:4 Percentile:20.93(Physics, Applied)

The oxidation reaction mechanisms for Si(001) by O$$_{2}$$ molecules have been investigated in a surface temperature region from 860 K to 1300 K and in an incident energy region from 0.6 eV to 3.0 eV. Synchrotron Radiation photoemission spectroscopy was used for surface analysis. Si-2p photoemission spectra were measured during molecular beam irradiation so that their dependences on surface temperature and incident energy were clarified. SiO molecules, desorbed from the surface at high temperature region, were also detected by a quadrupole mass analyzer using $$^{18}$$O$$_{2}$$ molecular beams to measure SiO desorption yield depending on surface temperature and incident energy. Consequently, a reaction scheme, oxide layers formation, etching, and coexistence of both reactions, is determined by the incident energy under 1000 K.

Journal Articles

Bubble dynamics in the thermal shock problem of the liquid metal target

Ishikura, Shuichi*; Kogawa, Hiroyuki; Futakawa, Masatoshi; Kikuchi, Kenji; Hino, Ryutaro; Arakawa, Chuichi

Journal of Nuclear Materials, 318, p.113 - 121, 2003/05

 Times Cited Count:12 Percentile:64.02(Materials Science, Multidisciplinary)

The thermal shock stress in the mercury target vessel was analyzed: the target receives the incident proton beam at the energy of 1 MW with the pulse duration of 1ms. Negative pressure of maximal 61MPa was generated when the initial pressure of 52MPa propagated in mercury. It is expected then that the cavitation may be arisen by the negative pressure. So in order to know the cavitation behavior, the simulation study was carried out by using the equation of motion based on the bubble dynamics for a single bubble, and fundamental parameter analysis was carried out. It is found that a bubble has a potential expansion more than 1000 times with a change of the pressure at the window of the target vessel. Consequently wave propagation will be affected. Theoretical consideration was given to the wave motion of propagation in bubbly liquid. The equation of state in bubbly liquid can be approximated by the polynomial. The diameter of a bubble and the bubble volume fraction inherent in mercury can be decided if the critical pressure, the sound velocity, and resonance frequency is successfully measured by static and dynamic experiment.

Journal Articles

Reaction dynamics of Si(001) oxidation at room temperature induced by supersonic O$$_{2}$$ molecular beams

Teraoka, Yuden; Yoshigoe, Akitaka

Hyomen Kagaku, 23(9), p.553 - 561, 2002/09

no abstracts in English

Journal Articles

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.

Journal Articles

Photoemission study on the surface reaction dynamics of Si(001) oxidation by supersonic O$$_{2}$$ molecular beams

Teraoka, Yuden; Yoshigoe, Akitaka

SPring-8 Research Frontiers 2000/2001, p.48 - 50, 2001/00

no abstracts in English

Journal Articles

Molecular dynamics simulation of atomic beam bombardment in solid surface

*; Kunugi, Tomoaki

Microscale Thermophys. Eng., 1(2), p.137 - 142, 1997/00

no abstracts in English

Journal Articles

Molecular beam study on infrared multiphoton dissociation of octafluorocyclobutane

; Yokoyama, Keiichi;

Chemical Physics Letters, 237, p.106 - 110, 1995/05

 Times Cited Count:12 Percentile:44.37(Chemistry, Physical)

no abstracts in English

Journal Articles

Numerical analysis of melting and evaporation behavior of molybdenum layer irradiated with a laser beam

Kunugi, Tomoaki; *

Nihon Kikai Gakkai Rombunshu, B, 61(585), p.1826 - 1833, 1995/05

no abstracts in English

18 (Records 1-18 displayed on this page)
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