Distribution of the Cs/Cs ratio around the Fukushima Daiichi Nuclear Power Plant using an unmanned helicopter radiation monitoring system

Nishizawa, Yukiyasu; Yoshida, Mami; Sanada, Yukihisa; Torii, Tatsuo

Journal of Nuclear Science and Technology, 53(4), p.468 - 474, 2016/04

https://doi.org/10.1080/00223131.2015.1071721

Science from the initial operation of HRC

Ito, Shinichi*; Yokoo, Tetsuya*; Masuda, Takatsugu*; Yoshizawa, Hideki*; Soda, Minoru*; Ikeda, Yoichi*; Ibuka, Soshi*; Kawana, Daichi*; Sato, Taku*; Nambu, Yusuke*; et al.

JPS Conference Proceedings (Internet), 8, p.034001_1 - 034001_6, 2015/09

https://doi.org/10.7566/JPSCP.8.034001

Progress in long-pulse production of powerful negative ion beams for JT-60SA and ITER

Kojima, Atsushi; Umeda, Naotaka; Hanada, Masaya; Yoshida, Masafumi; Kashiwagi, Mieko; Tobari, Hiroyuki; Watanabe, Kazuhiro; Akino, Noboru; Komata, Masao; Mogaki, Kazuhiko; et al.

Nuclear Fusion, 55(6), p.063006_1 - 063006_9, 2015/06

https://doi.org/10.1088/0029-5515/55/6/063006

Significant progresses in the extension of pulse durations of powerful negative ion beams have been made to realize the neutral beam injectors for JT-60SA and ITER. In order to overcome common issues of the long pulse production/acceleration of negative ion beams in JT-60SA and ITER, the new technologies have been developed in the JT-60SA ion source and the MeV accelerator in Japan Atomic Energy Agency. As for the long pulse production of high-current negative ions for JT-60SA ion source, the pulse durations have been successfully increased from 30 s at 13 A on JT-60U to 100 s at 15 A by modifying the JT-60SA ion source, which satisfies the required pulse duration of 100 s and 70% of the rated beam current for JT-60SA. This progress was based on the R&D efforts for the temperature control of the plasma grid and uniform negative ion productions with the modified tent-shaped filter field configuration. Moreover, the each parameter of the required beam energy, current and pulse has been achieved individually by these R&D efforts. The developed techniques are useful to design the ITER ion source because the sustainment of the cesium coverage in large extraction area is one of the common issues between JT-60SA and ITER. As for the long pulse acceleration of high power density beams in the MeV accelerator for ITER, the pulse duration of MeV-class negative ion beams has been extended by more than 2 orders of magnitude by modifying the extraction grid with a high cooling capability and a high-transmission of negative ions. A long pulse acceleration of 60 s has been achieved at 70 MW/m (683 keV, 100 A/m) which has reached to the power density of JT-60SA level of 65 MW/m.

Origin of non-uniformity of the source plasmas in JT-60 negative ion source

Yoshida, Masafumi; Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Kashiwagi, Mieko; Grisham, L. R.*; Akino, Noboru; Endo, Yasuei; Komata, Masao; Mogaki, Kazuhiko; et al.

Plasma and Fusion Research (Internet), 8(Sp.1), p.2405146_1 - 2405146_4, 2013/11

https://doi.org/10.1585/pfr.8.2405146

Distributions of H and H in the source plasmas produced at the end-plugs of JT-60 negative ions source were measured by Langmuir probes and emission spectroscopy in order to experimentally investigate the cause of lower density of the negative ions extracted from end-plugs in the source. Densities of H and H in end-plugs of the plasma grid in the source were compared with those in the center regions. As a result, lower density of the negative ion at the edge was caused by lower beam optics due to lower and higher density of the H and H.

Resonant inelastic X-ray scattering study of charge excitations in superconducting and nonsuperconducting PrFeAsO

Jarrige, I.*; Nomura, Takuji; Ishii, Kenji; Gretarsson, H.*; Kim, Y.-J.*; Kim, J.*; Upton, M.*; Casa, D.*; Gog, T.*; Ishikado, Motoyuki*; et al.

Physical Review B, 86(11), p.115104_1 - 115104_4, 2012/09

https://doi.org/10.1103/PhysRevB.86.115104

We report the first observation by momentum-resolved resonant inelastic X-ray scattering of charge excitations in an iron-based superconductor and its parent compound, PrFeAsO and PrFeAsO respectively, with two main results. First, using calculations based on a 16 band model, we show that the energy of the lowest-lying excitations, identified as interband transitions of dominant , orbital character, exhibits a dramatic dependence on electron correlation. This enables us to estimate the Coulomb repulsion and Hund's coupling , and to highlight the role played by in these peculiar orbital-dependent electron correlation effects. Second, we show that short-range antiferromagnetic correlations, which are a prerequisite to the occurrence of these excitations at the point, are still present in the superconducting state.

Gamma-ray irradiation experiment of turbo molecular pump

Kinsho, Michikazu; Ogiwara, Norio; Wada, Kaoru*; Yoshida, Motoo*; Nakayasu, Tatsuo*; Yamato, Yukio*

Vacuum, 73(2), p.175 - 180, 2004/03

https://doi.org/10.1016/j.vacuum.2003.12.015

The turbo molecular pump which can be operated exposed to high radiation has been developing at JAERI and Osaka Vacuum Ltd., because it is planed to use this turbo molecular pump for the 3GeV-RCS of the J-PARC project. The goal of irradiation dose is 30 MGy because the cumulative energy dose due to radiation is approximately estimated to be on the order of 100 MGy for 30 years of the 3GeV-RCS operation. In order to know radiation damage of turbo molecular pump, gamma-ray irradiation experiment has been performed at JAERI. The turbo molecular pump could operate properly less than 3.5 MGy absorption dose under gamma-ray irradiation environment. Since the elongation of elastomer vacuum seals became small due to exposed to radiation, this radiation damage of elastomer seals causes leak. The turbo molecular pump components except the elasomer seals, for example motor coil, control sensor, and etc, have kept high performance more than 7 MGy absorption dose. The turbo molecular pump without elastomer seals has been developed and the irradiation test will be started form April.

Non-dimensional transport scaling and its correlation with local transport properties in JT-60U plasmas

Shirai, Hiroshi; Takizuka, Tomonori; Kikuchi, Mitsuru; Mori, Masahiro; Nishitani, Takeo; Ishida, Shinichi; Kamada, Yutaka; Sato, Masayasu; Isei, Nobuaki; Koide, Yoshihiko; et al.

IAEA-CN-60/A2-17, 0, p.355 - 364, 1995/00

no abstracts in English

Improvement of confinement and remote radiative cooling of beam heated plasmas in JT-60 with ion ▽B drift towards the X-point

Tsuji, Shunji; Hosogane, Nobuyuki; Itami, Kiyoshi; Kubo, Hirotaka; Nishitani, Takeo; Shimada, Michiya; Koide, Yoshihiko; ; Sugie, Tatsuo; Nagashima, Keisuke; et al.

Nuclear Fusion, 32(8), p.1313 - 1330, 1992/00

https://doi.org/10.1088/0029-5515/32/8/I02

no abstracts in English

Helium ash exhaust studies with core fueling by a helium beam; L-mode divertor discharges with neutral-beam heating in the JT-60 tokamak

Nakamura, Hiroo; Hirayama, Toshio; Koide, Yoshihiko; Tobita, Kenji; Tani, Keiji; Fukuda, Takeshi; Kubo, Hirotaka; Kuriyama, Masaaki; Kusama, Yoshinori; Sakasai, Akira; et al.

Physical Review Letters, 67(19), p.2658 - 2661, 1991/11

https://doi.org/10.1103/PhysRevLett.67.2658

no abstracts in English

Particle confinement characteristics and helium ash exhaust experiments in JT-60 tokamak

Nakamura, Hiroo; Tsuji, Shunji; Shimizu, Katsuhiro; Hirayama, Toshio; Hosogane, Nobuyuki; Yoshida, Hidetoshi; Tobita, Kenji; Koide, Yoshihiko; Nishitani, Takeo; Nagashima, Keisuke; et al.

Kaku Yugo Kenkyu, 65(SPECIAL ISSUE), p.261 - 285, 1991/03

no abstracts in English