Effect of high temperature annealing on ferromagnetism induced by energetic ion irradiation in FeRh alloy

Kosugi, Shinya*; Fujita, Naoki*; Matsui, Toshiyuki*; Hori, Fuminobu*; Saito, Yuichi; Ishikawa, Norito; Okamoto, Yoshihiro; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 269(9), p.869 - 872, 2011/05

https://doi.org/10.1016/j.nimb.2010.12.061

Effects of thermal annealing on ion-irradiation induced ferromagnetism of FeRh bulk alloy and the related structural change were investigated by means of superconducting quantum interference device (SQUID) and extended X-ray absorption fine structure (EXAFS), respectively. Depending on the annealing temperature from 100 to 500 C, the magnetization induced by 10 MeV iodine ion irradiation and the lattice structure of the alloy were remarkably changed. After 500 C annealing, the magnetization and the lattice ordering of the alloy become similar to the states before the irradiation. The experimental result indicates that the thermal relaxation of irradiation-induced atomic disordering dominates the magnetic state of ion-irradiated FeRh alloy.

Hardening of Al-Cu-Mg alloy by energetic ion irradiation

Mitsuda, Tomoaki*; Kobayashi, Ippei*; Kosugi, Shinya*; Fujita, Naoki*; Saito, Yuichi; Hori, Fuminobu*; Semboshi, Satoshi*; Kaneno, Yasuyuki*; Nishida, Kenji*; Soneda, Naoki*; et al.

Journal of Nuclear Materials, 408(2), p.201 - 204, 2011/01

https://doi.org/10.1016/j.jnucmat.2010.10.013

Dynamics of ion internal transport barrier in LHD heliotron and JT-60U tokamak plasmas

Ida, Katsumi*; Sakamoto, Yoshiteru; Yoshinuma, Mikiro*; Takenaga, Hidenobu; Nagaoka, Kenichi*; Hayashi, Nobuhiko; Oyama, Naoyuki; Osakabe, Masaki*; Yokoyama, Masayuki*; Funaba, Hisamichi*; et al.

Nuclear Fusion, 49(9), p.095024_1 - 095024_9, 2009/09

https://doi.org/10.1088/0029-5515/49/9/095024

Dynamics of ion internal transport barrier (ITB) formation and impurity transport both in the Large Helical Device (LHD) heliotron and JT-60U tokamak are described. Significant differences between heliotron and tokamak plasmas are observed. The location of the ITB moves outward during the ITB formation regardless of the sign of magnetic shear in JT-60U and the ITB becomes more localized in the plasma with negative magnetic shear. In LHD, the low Te/Ti ratio ( 1) of the target plasma for the high power heating is found to be necessary condition to achieve the ITB plasma and the ITB location tends to expand outward or inward depending on the condition of the target plasmas. Associated with the formation of ITB, the carbon density tends to be peaked due to inward convection in JT-60U, while the carbon density becomes hollow due to outward convection in LHD. The outward convection observed in LHD contradicts the prediction by neoclassical theory.

Effects of energetic heavy ion irradiation on the structure and magnetic properties of FeRh thin films

Fujita, Naoki*; Kosugi, Shinya*; Zushi, Yoshihiro*; Matsui, Toshiyuki*; Saito, Yuichi; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 267(6), p.921 - 924, 2009/04

https://doi.org/10.1016/j.nimb.2009.02.054

Development and management of the knowledge base for the geological disposal technology; Annual report 2006

Umeda, Koji; Oi, Takao; Osawa, Hideaki; Oyama, Takuya; Oda, Chie; Kamei, Gento; Kuji, Masayoshi*; Kurosawa, Hideki; Kobayashi, Yasushi; Sasaki, Yasuo; et al.

JAEA-Review 2007-050, 82 Pages, 2007/12

JAEA-Review-2007-050.pdf:28.56MB

This report shows the annual report which shows the summarized results and topic outline of each project on geological disposal technology in the fiscal year of 2006.

The Study plan on applicability to actual geological environment conditions of the engineering technology for geological disposal of high level nuclear-waste through the second phases in Horonobe Underground Research Project

Aoyanagi, Shigeo; Yui, Mikazu; Tanai, Kenji; Kawakami, Susumu; Fujita, Tomoo; Taniguchi, Naoki; Shibata, Masahiro; Konishi, Kazuhiro; Nishimura, Mayuka; Kikuchi, Hirohito*; et al.

JAEA-Review 2006-014, 61 Pages, 2006/03

JAEA-Review-2006-014.pdf:5.03MB

no abstracts in English

Effect of defect contained within weld metal on susceptibility of hydrogen embrittlement of carbon steel weld joint, 2

Kobayashi, Masato*; Takahashi, Rieko*; Asano, Hidekazu*; Taniguchi, Naoki; Fujita, Tomoo

no journal, , 

Susceptibility of hydrogen embrittlement of carbon steel weld joint was evaluated by slow strain rate testing (SSRT) in consideration of a diffusive hydrogen concentration and a presence of a fine flaw which is hard to detect by ultrasonic testing due to the dimension. In order to avoid an effect of metallurgical micro structure, normalized specimens were prepared to the SSRT. The results of SSRT showed the rupture elongation decreases with an increase in hydrogen concentration. And observation of the fracture surface and measurement of the hydrogen concentration in the specimens showed a generation of a crack initiated from fine flaw at up to a certain value of hydrogen concentration. Although decreasing of fracture strain was observed on the specimens fracture morphology, it was evaluated as no significant effect in comparison with the effect of the concentration of the diffusive hydrogen in the specimens. These results suggest that a presence of a fine flaw has a small impact on the hydrogen embrittlement of weld joint.

Structure analysis of lithium ion conductor LiAlGe(PO) by neutron diffraction

Fujita, Yasuhiro*; Takahashi, Haruyuki*; Sakuma, Takashi*; Igawa, Naoki

no journal, , 

The crystal structures of LiAlGe(PO) (x=0,0.5) were analyzed out by the Rietveld method applying the neutron powder diffraction data to investimate the increasing of the ionic conduction. We could refine those structures with a space group, -3. The Rietveld analyses reveal that Li mainly occupied at 3 site and partially at 18 site in those compound. It was found that the site occupancy for 18 site of LiAlGe(PO) was higher than that of LiGe(PO).