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.

A Plan of materials irradiation facility at J-PARC for development of ADS and high-power accelerator facilities

Maekawa, Fujio

JPS Conference Proceedings (Internet), 33, p.011042_1 - 011042_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011042

Development of beam window (BW) materials is one of crucial issues in development of accelerator driven nuclear transmutation systems (ADS). The BW is exposed to high energy protons and spallation neutrons, and also to corrosive lead-bismuth eutectic (LBE) alloy at high temperature of about 500C. Recently, not only high-power accelerators but also high-power targets are the rate-limiting factor for increasing the power of accelerator facilities in terms of radiation damage and heat removal. To study radiation damage on BW and target materials for high-power accelerator facilities including ADS, we are planning a materials irradiation facility by utilizing the proton beam of 400 MeV and 250 kW provided by the J-PARC's Linac. The target is flowing LBE alloy which is a candidate target and coolant material of ADS. When a steel sample is irradiated in the target for one year, the sample receives radiation damage of about 10 dpa at maximum which is equivalent to the yearly radiation damage of ADS's BW. In the current facility concept, the facility is equipped with a hot-laboratory for efficient post-irradiation examination. The facility will be outlined in this presentation.

The Origin of beam non-uniformity in a large Cs-seeded negative ion source

Hanada, Masaya; Seki, Takayoshi*; Takado, Naoyuki; Inoue, Takashi; Mizuno, Takatoshi*; Hatayama, Akiyoshi*; Kashiwagi, Mieko; Sakamoto, Keishi; Taniguchi, Masaki; Watanabe, Kazuhiro

Nuclear Fusion, 46(6), p.S318 - S323, 2006/06

https://doi.org/10.1088/0029-5515/46/6/S13

The origin of the beam non-uniformity, that is one of the key issues in large Cs-seeded negative ion sources for JT-60U and ITER, was experimentally examined by measuring correlations between the intensity of the H ion beam and plasma parameters such as an electron temperature and plasma density in the JAERI 10 A negative ion source. From the correlation between the beam intensity and the plasma parameters, it was foreseen that the beam non-uniformity was due to the localization of the plasma and/or H0 atoms caused by B x B drift of the fast electron from filaments. The filament position was modified to suppress the B x B drift, and then the spatial uniformity of the beam intensity was examined. By this modification, the root-mean-square deviation of the spatial beam intensity from the averaged value deceased to a half of that before modification while the beam intensity integrated along the longitudinal direction was kept to be constant. From this result, it was confirmed that one of the origin of the beam non-uniformity was caused by plasma localization.

Investigation of photo neutralization efficiency of high intensity H beam with Nd:YAG laser in J-PARC

Tomisawa, Tetsuo; Akikawa, Hisashi; Sato, Susumu; Ueno, Akira; Kondo, Yasuhiro; Oigawa, Hiroyuki; Sasa, Toshinobu; Hasegawa, Kazuo; Lee, S.*; Igarashi, Zenei*; et al.

Proceedings of 7th European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators (DIPAC 2005), p.275 - 277, 2005/00

http://accelconf.web.cern.ch/Accelconf/d05/PAPERS/POW018.PDF

The photo neutralization method with Nd:YAG laser for negative hydrogen ions has been expected as an available candidate for the transverse beam profile measurement. The fraction of photo detached electron can also be used for charge exchange procedure to extract very low power proton beam for Transmutation Experimental Facility in J-PARC. The laser system has advantages of maintenance and radiation hardness in high intensity proton accelerators. In order to establish the low power beam extraction system and beam profile monitor, the photo neutralization efficiency must be surveyed in practical beam line with high intensity H beam. In this paper, an experimental set-up and preliminary results of photo neutralization method for intense H beam in J-PARC MEBT1 are described.

Characterization of neutron beams for boron neutron capture therapy; In-air radiobiological dosimetry

Yamamoto, Tetsuya*; Matsumura, Akira*; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Hori, Naohiko; Torii, Yoshiya; Shibata, Yasushi*; Nose, Tadao*

Radiation Research, 160(1), p.70 - 76, 2003/07

https://doi.org/10.1667/RR3012

The survival curves and the RBE for the dose components generated in boron neutron capture therapy (BNCT) were determined separately in neutron beams at JRR-4. The surviving fractions of V79 cells with or without 10B were obtained using an epithermal neutron beam (ENB), a mixed thermal-epithermal neutron beam (TNB-1), and a thermal (TNB-2) neutron beam. The cell killing effect of the neutron beam in the presence or absence of 10B was highly dependent on the neutron beam used and depended on the epithermal and fast-neutron content of the beam. The RBEs of the boron capture reaction were 4.07, 2.98 and 1.42, and the RBEs of the high-LET dose components based on the hydrogen recoils and the nitrogen capture reaction were 2.50, 2.34 and 2.17 for ENB, TNB-1 and TNB-2, respectively. The approach to the experimental determination of RBEs allows the RBE-weighted dose calculation for each dose component of the neutron beams and contributes to an accurate inter-beam comparison of the neutron beams at the different facilities employed in ongoing and planned BNCT clinical trials.

Dosimetry for a few hundred keV electron beams

Kojima, Takuji; Hakoda, Teruyuki; Sunaga, Hiromi; Takizawa, Haruki; Hanaya, Hiroaki

Proceedings of 9th International Conference on Radiation Curing (RadTech Asia '03) (CD-ROM), 4 Pages, 2003/00

Dosimetry study for 300 keV electron beams was performed using Gafchromic film dosimeters having 8-m thick radiation-sensitive layer for dose rate measurement, a prototype total-absorption aluminum calorimeter for energy fluence measurement and semi-empirical calculation using EDMULT code for depth-dose distribution estimation. The three preliminary results are compared concerning to dose rate distribution and energy fluence as a function of depth in air. Influences in dosimetry for 300 keV electrons are discussed based on these results.

Fast potential changes at H-mode transition in the JFT-2M tokamak

Hamada, Y.*; Ido, Tsuyoshi*; Kamiya, Kensaku*; *; Kawasumi, Y.*; Miura, Yukitoshi; JFT-2M Group

IAEA-CN-69/PDP/01 (CD-ROM), 4 Pages, 1999/00

no abstracts in English

Local transport analysis of L-mode plasmas in JT-60 tokamak

Hirayama, Toshio; Kikuchi, Mitsuru; Shirai, Hiroshi; Shimizu, Katsuhiro; Yagi, Masatoshi; Koide, Yoshihiko; Ishida, Shinichi; Azumi, Masafumi

JAERI-M 91-026, 28 Pages, 1991/03

JAERI-M-91-026.pdf:1.01MB

no abstracts in English

Plasma shapes for achieving high heating efficiency during neutral beam injection in doublet III

; ; ; *; ; *; ; ; ; ; et al.

Japanese Journal of Applied Physics, 23(5), p.L316 - L318, 1984/00

https://doi.org/10.1143/JJAP.23.L316

no abstracts in English

Development of Mach-Zehnder optical waveguide embedded in PDMS thin films by proton beam writing

Kada, Wataru*; Miura, Kenta*; Saruya, Ryota*; Kato, Hijiri*; Kubota, Atsushi*; Sato, Takahiro; Koka, Masashi; Ishii, Yasuyuki; Kamiya, Tomihiro; Nishikawa, Hiroyuki*; et al.

no journal, ,