Investigation of random beam trips in a linear accelerator at the Japan Proton Accelerator Research Complex for the development of an accelerator-driven nuclear transmutation system

Takei, Hayanori

Journal of Nuclear Science and Technology, 61(8), p.1075 - 1088, 2024/08

https://doi.org/10.1080/00223131.2023.2296039

In the proton linear accelerator (linac), the proton beam is unexpectedly interrupted due to the electrical discharge originating from the radio frequency, failure of the device/equipment, or other factors. Do these beam trips occur randomly? Conventionally, it has been implicitly assumed that beam trips occur randomly. In this study, we investigated whether beam trips in the linac of the Japan Proton Accelerator Research Complex (J-PARC) occur randomly to estimate the beam trip frequency in a superconducting proton linac for an accelerator-driven nuclear transmutation system. First, the J-PARC linac was classified into five subsystems. Then, the reliability function for the operation time in each subsystem was obtained using the Kaplan--Meier estimation, a reliability engineering methods. Using this reliability function, the randomness of beam trips was examined. Analysis of five-year operational data for five subsystems of the J-PARC linac showed that beam trips occurred randomly in some subsystems. However, beam trips did not occur randomly in many subsystems of the proton linac, including the ion source and the acceleration cavity, the primary subsystems of the proton linac.

Measurement of H particles generated by residual gas stripping in the Japan Proton Accelerator Research Complex linac

Tamura, Jun; Futatsukawa, Kenta*; Kondo, Yasuhiro; Liu, Y.*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*; Okabe, Kota; Yoshimoto, Masahiro

Nuclear Instruments and Methods in Physics Research A, 1049, p.168033_1 - 168033_7, 2023/04

https://doi.org/10.1016/j.nima.2023.168033

The Japan Proton Accelerator Research Complex (J-PARC) linac is a high-intensity accelerator in which beam loss is a critical issue. In the J-PARC linac, H beams are accelerated to 191~MeV by a separated drift tube linac (SDTL) and subsequently to 400~MeV by an annular-ring coupled structure (ACS). Because there are more beam loss mechanisms in H linacs than in proton linacs, it is imperative to investigate the beam loss circumstances for beam loss mitigation. Electron-stripping phenomena, which generate uncontrollable H particles, are characteristic beam loss factors of H linacs. To clarify the beam loss causes in the J-PARC linac, a new diagnostic line was installed in the beam transport between the SDTL and ACS. In this diagnostic line, H particles were separated from the H beam, and the intensity profiles of the H particles were successfully measured by horizontally scanning a graphite plate in the range where H particles were distributed. By examining the intensity variation of the H particles with different residual pressure levels, we proved that half of the H particles in the SDTL section are generated by the residual gas stripping in the nominal beam operation of the J-PARC linac.

Approaches to high power operation of J-PARC accelerator

Oguri, Hidetomo

Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.29 - 34, 2019/01

https://doi.org/10.18429/JACoW-LINAC2018-MO1P02

Commissioning the 400-MeV linac at J-PARC and high intensity operation of the J-PARC RCS

Hotchi, Hideaki; J-PARC Beam Commissioning Team

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.899 - 903, 2014/07

http://accelconf.web.cern.ch/AccelConf/IPAC2014/papers/tuxa01.pdf

In the summer shutdown of 2013, the output energy of the J-PARC linac was upgraded from 181 MeV to the design value of 400 MeV. With this upgraded injection energy, the following RCS has successfully demonstrated 550-kW high intense acceleration at a low-level beam loss of less than 0.5%. In this paper, we present the outcome of the recent high intensity beam trial performed in the RCS, together with the brief report on the beam commissioning status of the 400-MeV linac.

RF characteristics of J-PARC DTL3 cavity

Ito, Takashi; Asano, Hiroyuki*; Morishita, Takatoshi; Kato, Takao*; Takasaki, Eiichi*; Tanaka, Hirokazu*; Yoshino, Kazuo*; Naito, Fujio*

Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.242 - 244, 2005/07

The third Drift Tube Linac (DTL3) is adopted for 37MeV-50MeV part of high intensity proton linac for Japan Proton Accelerator Research Complex(J-PARC). DTL3 consists of 26 full drift tubes, 2 half drift tubes and 26 post-couplers. As a result of tuning of the accelerating field of the DTL3, the resonant frequency was adjusted to 324MHz and the average accelerating field distribution was adjusted within 1%.

R&D activities on accelerator-driven transmutation system in JAERI

Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Kikuchi, Kenji; Kurata, Yuji; Sasa, Toshinobu; Umeno, Makoto*; Saito, Shigeru; Nishihara, Kenji; Mizumoto, Motoharu; Takano, Hideki*; et al.

EUR-21227 (CD-ROM), p.483 - 493, 2005/00

JAERI is conducting the study on the dedicated transmutation system using the accelerator driven subcritical system (ADS). A subcritical reactor with the thermal power of 800 MW has been proposed. Many research and development activities including the conceptual design study are under way and planned at JAERI to examine the feasibility of the ADS. In the field of the proton accelerator, a superconducting LINAC is being developed. In the field of the spallation target using lead-bismuth eutectic (LBE), material corrosion, thermal-hydraulics, polonium behavior, and irradiation effect on materials are being studied. Moreover, in the framework of the J-PARC project, JAERI plans to construct the Transmutation Experimental Facility (TEF) to study the feasibility of the ADS using a high-energy proton beam and nuclear fuel and to establish the technology for the LBE spallation target and relevant materials.

Research activities for accelerator-driven transmutation system at JAERI

Sasa, Toshinobu

Progress in Nuclear Energy, 47(1-4), p.314 - 326, 2005/00

https://doi.org/10.1016/j.pnucene.2005.05.030

JAERI performs R&D of accelerator-driven systems (ADS) for transmutation of long-lived nuclides under national OMEGA program since 1988. To study the basic characteristics of ADS, Transmutation Experimental Facility is proposed under a framework of JAERI-KEK joint J-PARC project. A comprehensive R&D program for future ADS plant is also performed since 2002. R&D items are categorized into three fields, (1) accelerator (superconducting LINAC design), (2) lead-bismuth target/coolant (material compatibility, thermal-hydraulics around beam window and polonium behavior) and (3) subcritical core (system design, nuclear data, subcriticality measurement, and safety issues of ADS). First phase of the program will be done within three years. Assemble test of the cryomodule, heat transfer experiment using Pb-Bi thermal-hydraulics loop, cold test of polonium vaporization, design study of the 800MW ADS subcritical core are now underway. Part of this job was funded by the MEXT as one of the public offered R&D program for innovative nuclear systems.

Systematic calibration of beam position monitor at J-PARC LINAC

Sato, Susumu; Tomisawa, Tetsuo; Hiroki, Fumio; Lee, S.*; Igarashi, Zenei*; Ikegami, Masanori*; Ueno, Akira; Kondo, Yasuhiro; Hasegawa, Kazuo; Toyama, Takeshi*; et al.

Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.467 - 469, 2004/08

As a joint project of KEK and JAERI, a MW class of high intensity proton accelerator (J-PARC), consisting of Linac, 3 GeV-RCS, 50 GeV-MR, is under construction. For this accelerator, it is required to minimize the beam loss (typically, lower than0.11 W/m at the linac). To achieve the requirement, beam trajectory needs to be controlled with accuracy of some 100 m. The first stage of the acceleration (up to 181 MeV during the first stage of construction) is done by linac. The beam position monitor (BPM) in the linac utilizes 4 stripline pickups (50 ohm) on the beam transportation chamber. In this paper, systematic calibration of the BPM is described.

Systematic calibration of beam position monitor in the high intensity proton accelerator (J-PARC) linac

Sato, Susumu; Igarashi, Zenei*; Lee, S.*; Tomisawa, Tetsuo; Hiroki, Fumio; Kishiro, Junichi; Ikegami, Masanori*; Kondo, Yasuhiro; Hasegawa, Kazuo; Ueno, Akira; et al.

Proceedings of 22nd International Linear Accelerator Conference (LINAC 2004), p.429 - 431, 2004/00

As a joint project of KEK and JAERI, a MW class of high intensity proton accelerator (J-PARC), consisting of Linac, 3 GeV-RCS, 50 GeV-MR, is under construction at Tokai, Japan. For this accelerator, it is required to minimize the beam loss (typically, lower than 0.11 W/m at the linac). To achieve the requirement, beam trajectory needs to be controlled with accuracy of some 100 micro-meter. The first stage of the acceleration (up to 181 MeV during the first stage of construction) is done by linac. The beam position monitor (BPM) in the linac utilizes 4 strip-line pickups (50 ohm) on the beam transportation chamber. In this paper, systematic calibration of the BPM is described.

Comparison between the experimental results and simulations of 30mA-RFQ for J-PARC

Kondo, Yasuhiro; Ueno, Akira*; Ikegami, Masanori*; Ikegami, Kiyoshi*

Proceedings of 28th Linear Accelerator Meeting in Japan, p.69 - 71, 2003/08

A 3.115m long, 324MHz, 3MeV radio-frequency quadrupole (RFQ) linac is used as the first RF accelerator of the J-PARC linac. We have performed RFQ simulations to provide a particle distribution for an end-to-end (from the RFQ entrance to the injection point of the rapid cycling synchrotron (RCS)) simulation of the J-PARC linac. Two simulation codes, PARMTEQM and TOUTATIS are used for the RFQ simulations. The simulated emittances show good agreements with the ones measured at the exit of the medium energy beam transport (MEBT).