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Journal Articles

Two-parameter model for optimizing target beam distribution with an octupole magnet

Meigo, Shinichiro; Oi, Motoki; Fujimori, Hiroshi*

Physical Review Accelerators and Beams (Internet), 23(6), p.062802_1 - 062802_24, 2020/06

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

As hadron accelerators for such as the ADS and spallation neutron source achieve increasing beam power, damage to targets is becoming increasingly severe. To mitigate this damage, nonlinear beam optics based on octupole magnets is attractive. Nonlinear optics can decrease the beam-focusing hazard due to failure of the rastering magnet. As a side effect of nonlinear optics, the beam size is known to expand drastically compared with linear optics. Nonlinear effects have been studied via a simplified filament model that ignores beam-divergence spread at the octupole magnet. In this study, a new generalized model is proposed for application to an octupole magnet, regardless of the filament-model approximation. It is found that the transverse distribution obtained by beam tracking can be specified by the introduction of only two parameters, namely the normalized octupole strength of $$K^{*}_8$$ and the $$cot phi$$ of the phase advance. To achieve the two antagonistic requirements of reduction of the beam-peak density and minimization of the beam loss, the transverse distribution is surveyed for a large range of beam position. It is found that a bell-shaped distribution with $$K^{*}_8 sim$$ 1 and $$cot phi sim$$ 3 can satisfy requirements. This result is applied to beam transport in the spallation neutron source at J-PARC. The calculation result given by the present model shows good agreement with the experimental data, and the peak current density is reduced by 50% compared with the linear-optics case.

Journal Articles

Long beam pulse extraction by the laser charge exchange method using the 3-MeV linac in J-PARC

Takei, Hayanori; Hirano, Koichiro; Meigo, Shinichiro; Tsutsumi, Kazuyoshi*

Proceedings of 8th International Beam Instrumentation Conference (IBIC 2019) (Internet), p.595 - 599, 2020/06

Japan Proton Accelerator Research Complex (J-PARC) has a plan to build the Transmutation Physics Experimental Facility (TEF-P), in which a 400-MeV proton beam will be delivered from negative hydrogen (H$$^{-}$$) accelerated by the linac. Since the TEF-P requires a stable proton beam with a power of less than 10 W, a steady and meticulous beam extraction method is required to extract a small amount of the proton beam from the high power beam using 250 kW. To fulfill this requirement, we have developed beam extraction based on the Laser Charge Exchange (LCE) method. For the demonstration present beam extraction technique, an experiment was conducted using H$$^{-}$$ beam accelerated by the 3-MeV linac at RFQ test-stand in J-PARC. As a result of the experiment with continuous wave (CW) of the Laser, a charge-exchanged long-pulsed H$$^{+}$$ beam with a power of about 0.70 W equivalent was successfully obtained under the TEF-P beam condition.

Journal Articles

Estimation of uncertainty in lead spallation particle multiplicity and its propagation to a neutron energy spectrum

Iwamoto, Hiroki; Meigo, Shinichiro

Journal of Nuclear Science and Technology, 57(3), p.276 - 290, 2020/03

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

This paper presents an approach to uncertainty estimation of spallation particle multiplicity of lead ($$^{rm nat}$$Pb), primarily focusing on proton-induced spallation neutron multiplicity ($$x_{pn}$$) and its propagation to a neutron energy spectrum. The $$x_{pn}$$ uncertainty is estimated from experimental proton-induced neutron-production double-differential cross sections (DDXs) and model calculations with the Particle and Heavy Ion Transport code System (PHITS). Uncertainties in multiplicities for $$(n,xn)$$, $$(p,xp)$$, and $$(n,xp)$$ reactions are then inferred from the estimated $$x_{pn}$$ uncertainty and the PHITS calculation. Using these uncertainties, uncertainty in a neutron energy spectrum produced from a thick $$^{rm nat}$$Pb target bombarded with 500 MeV proton beams, measured in a previous experiment, is quantified by a random sampling technique, and propagation to the neutron energy spectrum is examined. Relatively large uncertainty intervals (UIs) were observed outside the lower limit of the measurement range, which is prominent in the backward directions. Our findings suggest that a reliable assessment of spallation neutron energy spectra requires systematic DDX experiments for detector angles and incident energies below 100 MeV as well as neutron energy spectrum measurements at lower energies below $$sim$$1.4 MeV with an accuracy below the quantified UIs.

Journal Articles

Characterization of mechanical strain induced by lead-bismuth eutectic (LBE) freezing in stainless steel cup

Ohdaira, Naoya*; Saito, Shigeru

Heliyon (Internet), 6(2), p.e03429_1 - e03429_8, 2020/02

Lead-bismuth eutectic (LBE) is a candidate liquid metal coolant for a fast reactor, especially accelerator driven system (ADS). Freeze sealed valve is a candidate design to be possible to add passive safety to the reactor. On the other hand, since LBE is known that it causes expansion after its solidification, quantitative evaluation of the stress to the pipe produced by the LBE expansion should be considered. Many researchers produced related data for the expansion, however, evaluations of the strain by LBE expansion was barely reported. Therefore, the strain measurement using a stainless steel cup and the stress evaluation was performed together with visual observation using an optical microscopy. The results indicated keeping above room temperature (RT) was a significantly effective way to reduce the strain to the pipe.

Journal Articles

Measurement of displacement cross section of structural materials utilized in the proton accelerator facilities with the kinematic energy above 400 MeV

Meigo, Shinichiro; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*

JPS Conference Proceedings (Internet), 28, p.061004_1 - 061004_6, 2020/02

no abstracts in English

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

Electromagnetic design of the low beta cavities for the JAEA ADS

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

Journal of Physics; Conference Series, 1350(1), p.012197_1 - 012197_7, 2019/12

Journal Articles

Design of the elliptical superconducting cavities for the JAEA ADS

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

Journal of Physics; Conference Series, 1350(1), p.012198_1 - 012198_6, 2019/12

Journal Articles

Electromagnetic design of the prototype spoke cavity for the JAEA-ADS linac

Tamura, Jun; Kondo, Yasuhiro; Yee-Rendon, B.; Meigo, Shinichiro; Maekawa, Fujio; Hasegawa, Kazuo; Kako, Eiji*; Umemori, Kensei*; Sakai, Hiroshi*; Konomi, Taro*

Proceedings of 19th International Conference on RF Superconductivity (SRF 2019) (Internet), p.399 - 402, 2019/11

Journal Articles

The Analytical study of inventories and physicochemical configuration of spallation products produced in Lead-Bismuth Eutectic of Accelerator Driven System

Miyahara, Shinya*; Ohdaira, Naoya*; Arita, Yuji*; Maekawa, Fujio; Matsuda, Hiroki; Sasa, Toshinobu; Meigo, Shinichiro

Nuclear Engineering and Design, 352, p.110192_1 - 110192_8, 2019/10

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Lead-Bismuth Eutectic (LBE) is used as a spallation neutron target and coolant materials of Accelerator Driven System (ADS), and many kinds of elements are produced as spallation products. It is important to evaluate the release and transport behavior of the spallation products in the LBE. The inventories and the physicochemical composition of the spallation products produced in LBE have been investigated for an LBE loop in the ADS Target Test Facility (TEF-T) in J-PARC. The inventories of the spallation products in the LBE were estimated using the PHITS code. The physicochemical composition of the spallation products in the LBE was calculated using the Thermo-Calc code under the conditions of the operation temperatures of LBE from 350$$^{circ}$$C to 500$$^{circ}$$C and the oxygen concentrations in LBE from 10 ppb to 1 ppm. The calculation showed that the 5 elements of Rb, Tl, Tc, Os, Ir, Pt, Au and Hg were soluble in LBE under the all given conditions and any kinds of compound were not formed in LBE. It was suggested that the oxides of Ce, Sr, Zr and Y were stable as CeO$$_{2}$$, SrO, ZrO$$_{2}$$ and Y$$_{2}$$O$$_{3}$$ in the LBE.

JAEA Reports

Development of prototype for TEF-T integral control system of J-PARC

Sakai, Kenji; Obayashi, Hironari; Saito, Shigeru; Sasa, Toshinobu; Sugawara, Takanori; Watanabe, Akihiko*

JAEA-Technology 2019-009, 18 Pages, 2019/07

JAEA-Technology-2019-009.pdf:2.34MB

Construction of Transmutation Experimental Facility (TEF) is under planning in the Japan Proton Accelerator Research Complex (J-PARC) program to promote R&D on the transmutation technology with using accelerator driven systems (ADS). ADS Target Test Facility (TEF-T) in TEF will develop spallation target technology and study on target materials with irradiating high intensity proton beams on a lead-bismuth eutectic (LBE) target. For safe and efficient beam operation, a general control system (GCS) will be constructed in TEF-T. GCS comprises several subsystems, such as a network system (LAN), an integral control system (ICS), an interlock system (ILS), and a timing distribution system (TDS) according to their roles. Especially, the ICS plays the important role that executes integral operations in the entire facility, acquires, stores and distributes operation data. We planned to develop a prototype of the ICS, to evaluate its concrete performances such as data transmission speeds, data storage capability, control functions, long-term stability of the system, and to utilize them for design of the actual ICS. This report mentions to product the prototype of ICS and to apply it to remote operations of instruments for developing LBE target technology.

Journal Articles

Development of profile monitors on target for high-intensity proton accelerators

Meigo, Shinichiro; Takei, Hayanori; Matsuda, Hiroki; Yuri, Yosuke*; Yuyama, Takahiro*

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.515 - 519, 2019/07

no abstracts in English

Journal Articles

Cavity and optics design of the accelerator for the JAEA-ADS project

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

Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.107 - 111, 2019/07

Journal Articles

Numerical study on the potential of cavitation damage in a lead-bismuth eutectic spallation target

Wan, T.; Naoe, Takashi; Kogawa, Hiroyuki; Futakawa, Masatoshi; Obayashi, Hironari; Sasa, Toshinobu

Materials, 12(4), p.681_1 - 681_15, 2019/02

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Journal Articles

Thermal-hydraulic analysis of the LBE spallation target head in JAEA

Wan, T.; Obayashi, Hironari; Sasa, Toshinobu

Nuclear Technology, 205(1-2), p.188 - 199, 2019/01

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Shielding

Maekawa, Fujio

Hamon, 28(4), p.208 - 211, 2018/11

Adequate shielding of neutrons and associated $$gamma$$-rays is of importance from viewpoints of the radiation safety of researchers and good experimental data taking by reducing the background. This article introduces basics of neutron shielding, physics and suitable materials for neutron and $$gamma$$-ray shielding, and an example of conceptual shielding design for the 1-MW spallation neutron source of J-PARC MLF.

JAEA Reports

Measurement experiment of oxygen concentration in liquid lead-bismuth eutectic; Basic Tests and estimation of gamma-ray irradiation effect

Sugawara, Takanori; Kita, Satoshi*; Yoshimoto, Hidemitsu*; Okubo, Nariaki

JAEA-Technology 2018-008, 26 Pages, 2018/09

JAEA-Technology-2018-008.pdf:10.35MB

The oxygen sensors to measure the oxygen concentration in liquid LBE (lead-bismuth eutectic) were fabricated and tested for future use in LBE-cooled ADS (accelerator-driven system) or LBE test loops. The following tests were performed; estimation of catalyst application range, freeze seal structure and estimation of gamma-ray irradiation effect. For the estimation of the catalyst application range, it was confirmed that the measurement accuracy became worse in low LBE temperature as the application range became small. For the freeze seal structure, we realized the structure to prevent the LBE leakage with 0.5 MPa pressure condition. For the estimation of gamma-ray irradiation effect, the ex-situ test was carried out and it was observed that there was little effect by 4 MGy gamma-ray irradiation.

Journal Articles

Accelerator Driven nuclear transmutation System (ADS)

Maekawa, Fujio

Koenerugi Kasokuki Semina, OHO '18 Jukoyo Tekisuto, 11 Pages, 2018/09

no abstracts in English

Journal Articles

Flow-accelerated corrosion of type 316L stainless steel caused by turbulent lead-bismuth eutectic flow

Wan, T.; Saito, Shigeru

Metals, 8(8), p.627_1 - 627_22, 2018/08

 Times Cited Count:2 Percentile:65.61(Materials Science, Multidisciplinary)

Journal Articles

Development of profile monitors on target for high-intensity proton accelerators

Meigo, Shinichiro; Takei, Hayanori; Matsuda, Hiroki; Yuri, Yosuke*; Yuyama, Takahiro*

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1035 - 1039, 2018/08

no abstracts in English

136 (Records 1-20 displayed on this page)