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Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Miyamoto, Ryoichi*; Milas, N.*; Eshraqi, M.*
Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.58 - 62, 2026/04
The European Spallation Source (ESS) superconducting proton linac is currently undergoing commissioning. During the initial operation phase, the final beam energy will be about 800 MeV, reaching a 2 MW power. High reliability and availability are crucial for the success of the ESS science programs and thus operations will be maintained even with failures of main linac components such as cavities and quadrupoles, as long as ~50 percent of the intended power can be achieved. To this end, we developed beam optics strategies to address failures in the cavities of the superconducting linac. Due to the constraints in the RF cavity amplitudes, we implemented a modified version of standard cavity compensation techniques. The results indicated that this strategy enables beam recovery that meets the beam quality specifications, thereby enhancing the availability of the ESS linac.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Pla
ais, A.*; Bouly, F.*
Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.316 - 320, 2026/04
High-intensity accelerators, particularly Accelerator-Driven Systems (ADS), require high availability and reliability for proper operation. For superconducting linear accelerators, the ability to continue operating even when one of the RF cavities fails is key to achieving the required availability, known as cavity compensation. Beam dynamics studies of the JAEA-ADS linear accelerator have demonstrated the possibility of operating with multiple RF cavities disabled with acceptable beam quality. Several other superconducting linear accelerator laboratories have adopted similar methods and developed their procedures. Among these efforts, the LightWin tool has proven to be an effective tool for automatically and systematically identifying compensation settings for each cavity failure in any linear accelerator. This software has been successfully utilized on the MINERVA linac, as well as on the high-energy part of the JAEA-ADS linac. It has currently been tested and improved to ease SPIRAL2 operation. This work presents an analysis of cavity compensation in the JAEA-ADS superconducting linear accelerator using the LightWin tool and compares the results with previous studies.
Nishihara, Kenji; Fukushima, Masahiro; Abe, Takumi; Katano, Ryota; Yee-Rendon, B.; Iwamoto, Hiroki; Sugawara, Takanori; Obayashi, Hironari; Saito, Shigeru
JAEA-Research 2025-013, 125 Pages, 2026/03
JAEA-Research-2025-013.pdf:4.68MB
A conceptual design for a pilot Accelerator Driven subcritical System (ADS) was developed as a precursor to a commercial ADS aimed at partitioning and transmutation of minor actinides. The output of the pilot ADS was set at 200 MW. Based on safety assessment results, the design incorporates deep subcriticality and safety rods. Core design, accelerator design, target design, and in-vessel equipment design were performed, clarifying the specific concept.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio
Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.130 - 134, 2026/03
Accelerator-Driven Systems (ADS) represent an efficient solution to the challenge of nuclear waste disposal. Therefore, the Japan Atomic Energy Agency (JAEA) is designing a 30-MW proton linac as a key element of its proposal for the use of ADS technology. A key feature of ADS accelerators is their extremely high availability and reliability that is required to avoid thermal stress on reactor structures. To this end, JAEA-ADS adopted a combined strategy of hot standby in the front part of the linac and standby element compensation as a fast and efficient way to reduce the downtime due to an element failure. The JAEA-ADS injector is mainly composed of a normal conducting section and ends with the first section of superconducting cavities (Half Wave Resonator). This paper presents the details of the optics design of the JAEA-ADS injector and the results of beam dynamics simulations.
Takei, Hayanori
Journal of Nuclear Science and Technology, 62(11), p.1051 - 1070, 2025/11
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The Japan Atomic Energy Agency is working on the research and development of an accelerator-driven nuclear transmutation system (ADS) for transmuting minor actinides. This system combines a subcritical nuclear reactor with a high-power superconducting proton linear accelerator (JADS-linac). One of the factors limiting the advancement of the JADS-linac is beam trips, which often induce thermal cycle fatigue, thereby damaging the components in the subcritical core. The average beam current of the JADS-linac is 32 times higher than that of the linear accelerator (linac) of the Japan Proton Accelerator Research Complex (J-PARC). Therefore, according to the development stage, comparing the beam trip frequency of the JADS-linac with the allowable beam trip frequency (ABTF) is necessary. Herein the beam trip frequency of the JADS-linac was estimated through a Monte Carlo program using the reliability functions based on the operational data of the J-PARC linac. The Monte Carlo program afforded the distribution of the beam trip duration, which cannot be obtained using traditional analytical methods. Results show that the frequency of the beam trips with a duration exceeding 5 min must be reduced to 27% of the current J-PARC linac level to be below the ABTF.
Kumada, Takayuki
For the Future of Hydrogen Science and Technology, 3(1), p.2 - 6, 2025/10
Yamaguchi, Yuji; Kondo, Yasuhiro; Meigo, Shinichiro; Shinozaki, Shinichi; Takayanagi, Tomohiro; Fujimori, Hiroshi*; Kawamura, Naritoshi*
Journal of Physics; Conference Series, 3094(1), p.012023_1 - 012023_5, 2025/09
The 3-GeV proton beam from the rapid cycling synchrotron (RCS) of J-PARC is transported to the spallation neutron source at Materials and Life Science Experimental Facility (MLF) by a 3-GeV RCS to Neutron facility Beam Transport (3NBT) line. Recently, the first design idea of a new proton beam transport line has been proposed for a future target station of the MLF (TS2). In the present study, proton beam transport is simulated near the TS2 target where a bending magnet and a solenoid are located for muon beam transport. The purposes are to clarify the magnetic field effects on the proton beam by the magnets and to present a method to correct each effect. Orbit deviation by the bending magnet and vertical size expansion due to profile rotation by the solenoid can be corrected by installing additional bending magnets and a solenoid with reversal magnetic field, respectively. The correction method is expected to be effective and also needs to be studied further for detail design.
Kim, H.*; Gubler, P.; Sasaki, Chihiro*
Physics Letters B, 866, p.139577_1 - 139577_4, 2025/07
Times Cited Count：1 Percentile：59.26(Astronomy & Astrophysics)Meigo, Shinichiro; Iwamoto, Hiroki; Sugihara, Kenta*; Hirano, Yukinori*; Tsutsumi, Kazuyoshi*; Saito, Shigeru; Maekawa, Fujio
JAEA-Technology 2024-026, 123 Pages, 2025/03
JAEA-Technology-2024-026.pdf:14.22MB
Based on the design of the ADS Target Test Facility (TEF-T) at the J-PARC Transmutation Experimental Facility, a conceptual study was conducted on the J-PARC proton beam irradiation facility. This research was carried out based on the recommendations of the Nuclear Transmutation Technology Evaluation Task Force of the MEXT. The recommendations state that it is desirable to consider facility specifications that can make the most of the benefits of using the existing J-PARC proton accelerator while also solving the engineering issues of the ADS. We considered facilities that could respond to a variety of needs while reducing the facilities that were not needed in the TEF-T design. In order to clarify these diverse needs, we investigated the usage status of representative accelerator facilities around the world. As a result, it became clear that the main purposes of these facilities were (1) Material irradiation, (2) Soft error testing of semiconductor devices using spallation neutrons, (3) Production of RI for medical use, and (4) Proton beam use, and we investigated the facilities necessary for these purposes. In considering the facility concept, we assumed a user community in 2022 and reflected user opinions in the facility design. This report summarizes the results of the conceptual study of the proton irradiation facility, various needs and responses to them, the roadmap for facility construction, and future issues.
Teshigawara, Makoto; Lee, Y.*; Tatsumoto, Hideki*; Hartl, M.*; Aso, Tomokazu; Iverson, E. B.*; Ariyoshi, Gen; Ikeda, Yujiro*; Hasegawa, Takumi*
Nuclear Instruments and Methods in Physics Research B, 557, p.165534_1 - 165534_10, 2024/12
Times Cited Count：1 Percentile：26.14(Instruments & Instrumentation)At Japanese Spallation Neutron Source in J-PARC, the para-hydrogen fraction was measured by using Raman spectroscopy in-situ for an integrated beam power of 9.4 MW
h at 1 MW operation, to evaluate the functionality of the ferric oxyhydroxide catalyst. This result showed that full functionality of the catalyst was retained up to the 1 MW operation. We attempted to study the effect of neutron scattering driven para to ortho-hydrogen back-conversion rate in the absence of the catalyst effect with a bypass line without catalyst. The measured increase of ortho-hydrogen fraction was 0.44% for an integrated beam power of 2.4 MWh at 500 kW operation, however, which was considered to be due to not only to neutron collisions in cold moderators but also to the high ortho-hydrogen fraction of initially static liquid hydrogen in the bypass line and passive exudation of quasi-static hydrogen in the catalyst vessel to the main loop.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Maekawa, Fujio; Meigo, Shinichiro
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.205 - 209, 2024/10
The Japan Atomic Energy Agency (JAEA) designs a 30-MW CW proton linear accelerator (linac) as a key component for the accelerator-driven subcritical system (ADS) project, aimed at nuclear waste management. The low energy beam transport (LEBT) in JAEA-ADS uses charge neutralization to minimize space-charge effects, which are the primary cause of beam loss in high-power accelerators. During commissioning and power ramp-up, precise control of the duty cycle is required for safety and machine protection; thus, a chopper system will be installed to manage the beam power. The chopper is located at the LEBT, to facilitate the disposal of the excess beam power, but its operation will affect the charge neutralization producing beam transients that could lead to beam loss. To shed light on this, we created a beam optics model for the chopper using an analytic approach to determine the required characteristics like voltage and dimensions, which was confirmed through TraceWin simulations. Subsequently, we analyzed the chopper's impact on space-charge compensation to evaluate the beam transients in the LEBT. This study reports the design of the chopper and its effects on beam performance for the JAEA-ADS LEBT.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Maekawa, Fujio; Meigo, Shinichiro
Proceedings of 32nd Linear Accelerator Conference (LINAC 2024) (Internet), p.488 - 491, 2024/10
The Japan Atomic Energy Agency (JAEA) is designing a 30-MW CW proton linear accelerator (linac) for nuclear waste transmutation. Space-charge is the primary challenge in achieving low losses and high beam quality for high-power accelerators, especially at low energy levels where space-charge forces are greater. To counteract the space-charge effects, the low-energy beam transport (LEBT) uses a magnetostatic design to enable the neutralization of the beam charge, the so-called space charge compensation. The neutralization is an accumulation process that reaches a charge balance between the main beam and the opposite ionized particles. However, this equilibrium is destroyed by the chopper system used during beam ramping. During those transient regimes, the beam optics conditions are not optimal for the beam, producing considerable degradation that can end in serious damage to the accelerator. Thus, analysis of beam behavior at these periods is essential to develop a robust design and an efficient operation of the JAEA-ADS linac. This study presents the beam dynamics of neutralization build-up and chopper operation for the JAEA-ADS LEBT.
Bi isotopesHuang, H.*; Andreyev, A. N.; 37 of others*
Physical Review C, 110(1), p.014326_1 - 014326_8, 2024/07
Times Cited Count：3 Percentile：59.72(Physics, Nuclear)
Mg, Si, Fe, Cu, and ZnSugihara, Kenta*; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio
Nuclear Instruments and Methods in Physics Research B, 549, p.165299_1 - 165299_12, 2024/04
Times Cited Count：1 Percentile：26.14(Instruments & Instrumentation)
Ti and 
Nb at 0.8 and 3.0 GeVSugihara, Kenta*; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio
Nuclear Instruments and Methods in Physics Research B, 545, p.165153_1 - 165153_9, 2023/12
Times Cited Count：2 Percentile：31.51(Instruments & Instrumentation)Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Maekawa, Fujio; Meigo, Shinichiro
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.545 - 549, 2023/11
The Japan Atomic Energy Agency (JAEA) is proposing a 30-MW proton linear accelerator (linac) for the application of accelerator-driven subcritical system (ADS) technology to achieve nuclear waste transmutation. A major challenge for the JAEA-ADS linac is the efficient transport of a 35 keV proton beam from the ion source to the radio-frequency quadrupole. In order to achieve this goal, we have optimized a magnetostatic low energy beam transport (LEBT) consisting of two solenoids to reduce the transmission of high-charge ions generated by the source and minimize the growth of proton emittance, while taking into account various space-charge compensation scenarios. In this report, we present the optical design and discuss the multiparticle tracking results of the JAEA-ADS LEBT.
Sasaki, Yuji; Kaneko, Masashi; Ban, Yasutoshi; Kinoshita, Ryoma; Matsumiya, Masahiko*; Shinoku, Kota*; Shiroishi, Hidenobu*
Analytical Sciences, 39(9), p.1575 - 1583, 2023/09
Times Cited Count：3 Percentile：21.47(Chemistry, Analytical)Extraction of Rh from HCl can be performed by NTAamide(C6) (hexahexyl-nitrilotriacetamide) and other related compounds into n-dodecane. We use ion-pair extraction of anionic species of Rh-chloride and protonated extractant. Rh behave as anion in hydrochloric acid and the tertiary nitrogen atom in extractant may be protonated to produce the quaternary amine in acidic condition. From the present work, the maximum distribution ratio of Rh(III) is 16. The D(Rh) values are changeable during preparation of the aqueous solutions because different Rh-Cl-H
O complexes are formed in HCl media and show the slow exchange rate between Cl and HO. Using the UV spectrum, Rh-chloride solution having the peak of spectrum at 504 nm can be extracted effectively, where RhCl
(HO)
and RhCl
(H
O)
exist mainly from DFT calculation. Stoichiometry of one-one complex of Rh and NTAamide is obtained from slope analysis, and 85 mM of concentrated Rh ion can be extracted.
Tamura, Fumihiko; Omori, Chihiro*; Yoshii, Masahito*; Tomizawa, Masahito*; Toyama, Takeshi*; Sugiyama, Yasuyuki*; Hasegawa, Katsushi*; Kobayashi, Aine*; Okita, Hidefumi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.175 - 178, 2023/01
J-PARC MR delivers high intensity proton beams to the neutrino experiment. Eight bunches with high peak currents are extracted from the MR by the extraction kicker, therefore the neutrino beam has the similar structure. Intermediate Water Cherenkov Detector (IWCD) will be installed for the future experiments and the IWCD requires a time structure with low peaks. We consider bunch manipulation at flattop of the MR for reducing the peak current. It should be quickly done to avoid the significant loss of the beam power. The beam gap for the kicker rise time must be kept. We propose a non-adiabatic bunch manipulation using the multiharmonic rf voltage. The longitudinal impedance in the MR can affect the beam stability. The feasibility of the manipulation is discussed by using the longitudinal simulations.
Jameson, R. A.*; Yee-Rendon, B.
Journal of Instrumentation (Internet), 17(12), p.P12011_1 - P12011_11, 2022/12
Times Cited Count：1 Percentile：5.23(Instruments & Instrumentation)A new application of vane modulation variation in a Radio Frequency Quadrupole (RFQ) cell has been applied that significantly improves beam bunching and longitudinal emittance control to achieve lower longitudinal rms emittance at the RFQ output. This procedure occurs in the individual cells, is independent of the overall design, and therefore is general, affording an extra parameter for beam manipulation. It can be applied besides the usual goals of vane modulation variation, e.g., to achieve higher acceleration efficiency. Examples of the cumulative effects on the overall design are provided to point out further exploration avenues for the designer.
Maekawa, Fujio
JAEA-Conf 2022-001, p.7 - 13, 2022/11
The partitioning and transmutation (P-T) technology has promising potential for volume reduction and mitigation of degree of harmfulness of high-level radioactive waste. JAEA is developing the P-T technology combined with accelerator driven systems (ADS). One of critical issues affecting the feasibility of ADS is the proton beam window (PBW) which functions as a boundary between the accelerator and the sub-critical reactor core. The PBW is damaged by a high-intensity proton beam and spallation neutrons produced in the target, and also by flowing high-temperature liquid lead bismuth eutectic alloy which is corrosive to steel materials. To study the materials damage under the ADS environment, J-PARC is proposing a plan of proton irradiation facility which equips with a liquid lead-bismuth spallation target bombarded by a 400 MeV - 250 kW proton beam. The facility is also open for versatile purposes such as soft error testing of semi-conductor devises, RI production, materials irradiation for fission and fusion reactors, and so on. Application to nuclear data research with using the proton beam and spallation neutrons is also one of such versatile purposes, and we welcome unique ideas from the nuclear data community.
