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Journal Articles

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

 Times Cited Count:28 Percentile:27.98(Physics, Fluids & Plasmas)

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 $$nabla$$B drift of the fast electron from filaments. The filament position was modified to suppress the B x $$nabla$$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.

Journal Articles

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

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.

Journal Articles

3-45MeV/u ion beam dosimetry using thin film dosimeters

Kojima, Takuji; Sunaga, Hiromi; Takizawa, Haruki*; Hanaya, Hiroaki; Tachibana, Hiroyuki*

Radiation Physics and Chemistry, 68(6), p.975 - 980, 2003/12

 Times Cited Count:2 Percentile:79.95(Chemistry, Physical)

Four kinds of film dosimeters well-characterized for low LET radiations were applied to 3-45 MeV/u ions. The dose responses relative to those for low LET radiations are almost one up to about 10 MeV/(mg/cm$$^{2}$$) and gradually become smaller with increase of the stopping power. Overall uncertainty in ion beam dosimetry using these characterized dosimeters is better than $$pm$$5%(1$$sigma$$) including uncertainty in fluence measurement($$pm$$2%). Lateral and depth dose profile measurements were achievable using characterized Gafchromic dosimeters with the spatial resolution of better than 1 and 10 $$mu$$m, respectively.

Journal Articles

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

 Times Cited Count:13 Percentile:62.08(Biology)

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.

Journal Articles

Flat-top acceleration system for the variable-energy multiparticle AVF cyclotron

Fukuda, Mitsuhiro; Kurashima, Satoshi; Okumura, Susumu; Miyawaki, Nobumasa; Agematsu, Takashi; Nakamura, Yoshiteru; Nara, Takayuki; Ishibori, Ikuo; Yoshida, Kenichi; Yokota, Wataru; et al.

Review of Scientific Instruments, 74(4), p.2293 - 2299, 2003/04

 Times Cited Count:14 Percentile:38.68(Instruments & Instrumentation)

A combination of the fundamental- and the fifth-harmonic voltages is ideally suited for flat-top acceleration in a variable-energy multi-particle cyclotron for energy-spread minimization. The flat-topping of the energy gain distribution using the fifth-harmonics has the advantages of minimizing an amplifier power, reducing power dissipation in a resonator and increasing the energy gain per turn. The flat-top acceleration system of the JAERI AVF cyclotron was designed to reduce the energy spread to 0.02 $$%$$, required for microbeam production. Tolerable fluctuations of acceleration voltages and the magnetic excitation were 2.0$$times$$10$$^{-4}$$ for the fundamental voltage, 1.0$$times$$10$$^{-3}$$ for the fifth-harmonic voltage, and 1.9$$times$$10$$^{-5}$$ for the magnetic field. In order to enhance compactness of the flat-topping cavity and to make a substantial saving of the amplifier power, optimum geometric parameters of the flat-topping cavity were determined by a cold model test and a calculation using the MAFIA code.

Journal Articles

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-$$mu$$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.

Journal Articles

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

Journal Articles

High performance and current drive experiments in the JAERI Tokamak-60 Upgrade

Kondoh, Takashi; JT-60 Team

Physics of Plasmas, 1(5), p.1489 - 1496, 1994/05

 Times Cited Count:19 Percentile:41.07(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

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

 Times Cited Count:3 Percentile:72.82(Physics, Applied)

no abstracts in English

Journal Articles

Depth-dose distributions in an aluminum-blue-cellophane stack for a high-intensity pulsed electron beam in an atmosphere of helium

; ; Hotta, Hiroshi

Radiat.Res., 63(1), p.14 - 23, 1975/01

 Times Cited Count:10

no abstracts in English

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