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Journal Articles

Numerical interpretation of hydrogen thermal desorption spectra for iron with hydrogen-enhanced strain-induced vacancies

Ebihara, Kenichi; Sugiyama, Yuri*; Matsumoto, Ryosuke*; Takai, Kenichi*; Suzudo, Tomoaki

Metallurgical and Materials Transactions A, 52(1), p.257 - 269, 2021/01

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

We simulated the thermal desorption spectra of a small-size iron specimen to which was applied during charging with hydrogen atoms using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy clusters $$V_9$$, which is composed of nine vacancies and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduced the experimental spectra except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of $$V_2$$ and $$V_3$$ is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.

Journal Articles

Study on simulation of thermal desorption spectra for a tempered martensitic steel with vacancies induced by hydrogen and strain

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

"Suiso Zeika No Kihon Yoin To Tokusei Hyoka" Kenkyukai Hokokusho, p.57 - 61, 2018/09

no abstracts in English

Journal Articles

Determination of detrapping and trapping rate constants for hydrogen based on experimental thermal desorption spectra

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

Proceedings of 2016 International Hydrogen Conference (IHC 2016); Materials Performance in Hydrogen Environments, p.470 - 477, 2017/00

For understanding hydrogen (H) embrittlement of steels, it is necessary to infer the state that defects trap H in the steels. Thermal desorption spectra of H obtained by the thermal desorption spectrometry (TDS) are used for inferring such a state. Because the thermal desorption spectra include the influence of experimental conditions and hydrogen diffusion as well as information of the defects trapping H, it is necessary to interpret the spectra using the numerical simulation. In the presentation, we determined the detrapping and the trapping rate constants which are necessary for the simulation from the experimental spectra obtained for plate specimens which is so small that H diffusion is ignorable. Then we confirmed that the model using the obtained rate constants can simulate the spectra of larger cylindrical specimens, so that it was found that the rate constant for small specimens can be used for the simulation of the spectra for specimens of different shape or size.

Journal Articles

Study on modeling of thermal desorption spectra of hydrogen including variation of vacancy-type trap sites

Ebihara, Kenichi; Saito, Kei*; Takai, Kenichi*

"Suiso Zeika No Kihon Yoin To Tokusei Hyoka Kenkyukai Chukan Hokokukai" Shimposium Yokoshu (USB Flash Drive), p.30 - 35, 2016/09

no abstracts in English

Journal Articles

Evaluation of temperature rise caused by AC loss due to plasma disruption in joint of JT-60SA poloidal field coil

Nakamura, Kazuya*; Yamamoto, Yusuke*; Suzuki, K.*; Takao, Tomoaki*; Murakami, Haruyuki; Natsume, Kyohei; Yoshida, Kiyoshi

IEEE Transactions on Applied Superconductivity, 25(3), p.4200704_1 - 4200704_4, 2015/06

 Times Cited Count:0 Percentile:100(Engineering, Electrical & Electronic)

Journal Articles

Thermal stability of butt joint for CS conductor in JT-60SA

Takao, Tomoaki*; Kawahara, Yuzuru*; Nakamura, Kazuya*; Yamamoto, Yusuke*; Yagai, Tsuyoshi*; Murakami, Haruyuki; Yoshida, Kiyoshi; Natsume, Kyohei*; Hamaguchi, Shinji*; Obana, Tetsuhiro*; et al.

IEEE Transactions on Applied Superconductivity, 24(3), p.4800804_1 - 4800804_4, 2014/06

 Times Cited Count:3 Percentile:74.36(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Long-lived, highly excited neutral hydrogen atom production following oxygen 1s photoexcitation of gas-phase water molecules

Harries, J.; Gejo, Tatsuo*; Homma, Kenji*; Kuniwake, Miki*; Sullivan, J. P.*; Lebech, M.*; Azuma, Yoshiro*

Journal of Physics B; Atomic, Molecular and Optical Physics, 44(9), p.095101_1 - 095101_7, 2011/05

 Times Cited Count:9 Percentile:51.78(Optics)

Journal Articles

Selective vibrational excitation in the resonant Auger decay following core-to-$$pi^*$$ transitions in N$$_2$$O

Travnikova, O.*; C$'e$olin, D.*; Bao, Z.*; B${o}$rve, K. J.*; Tanaka, Takahiro*; Hoshino, Masamitsu*; Kato, Hideki*; Tanaka, Hiroshi*; Harries, J.; Tamenori, Yusuke*; et al.

Journal of Electron Spectroscopy and Related Phenomena, 181(2-3), p.129 - 134, 2010/08

 Times Cited Count:1 Percentile:91.77(Spectroscopy)

In N$$_2$$O a detailed study of the vibrational distribution of the state reached after decay of core-to-$$pi^*$$ excitation of N terminal, N central and O 1s core levels is reported. We observe a change in the relative intensity of bending versus stretching modes while scanning the photon energy across all three resonances. While this effect is known to be due to the Renner-Teller splitting in the core-excited states, we could derive that the antisymmetric stretching is excited mainly in the decay of the N terminal 1s-to-$$pi^*$$ excitation. An explanation for such selectivity is provided in terms of interplay of vibrational structure on potential energy surfaces of different electronic states involved in the process.

Journal Articles

Photoabsorption spectra of CF$$_3$$I and thermally dissociated CF$$_3$$I near the C 1s, I 3d and F 1s ionisation thresholds

Tanaka, Takahiro*; Hoshino, Masamitsu*; Kato, Hideki*; Harries, J.; Tamenori, Yusuke*; Ueda, Kiyoshi*; Tanaka, Hiroshi*

Journal of Electron Spectroscopy and Related Phenomena, 164(1-3), p.24 - 27, 2008/07

 Times Cited Count:4 Percentile:73.59(Spectroscopy)

We report soft X-ray total ion yield and angular-resolved ion yield spectra of CF$$_3$$I in the C 1s, I 3d and F 1s ionisation regions, and tentatively assign the observed electronic states. Anisotropy in ion yield is observed only for the C 1s$$rightarrowsigma^*_{C-I}$$ transition, indicating that the dipole moment for this transition is parallel to the C$$_{3v}$$. The effusive source of CF$$_3$$I is heated to 800 K to produce a mixture of CF$$_3$$ and I, and the resulting spectra are compared to those recorded at room temperature to reveal the first information on the inner-shell excitation of CF$$_3$$.

Journal Articles

Softening of magnetic excitations leading to pressure-induced quantum phase transition in gapped spin system KCuCl$$_{3}$$

Goto, Kenji*; Osakabe, Toyotaka; Kakurai, Kazuhisa; Uwatoko, Yoshiya*; Osawa, Akira*; Kawakami, Jun*; Tanaka, Hidekazu*

Journal of the Physical Society of Japan, 76(5), p.053704_1 - 053704_4, 2007/05

 Times Cited Count:9 Percentile:46.96(Physics, Multidisciplinary)

The neutron scattering investigation on magnetic excitations in KCuCl$$_{3}$$ under applied pressure was performed. The softening of the excitation mode at a hydrostatic pressure of 4.7kbar was clearly observed. From the analysis of the dispersion relations, it was found that the intradimer interaction decreases under hydrostatic pressure, while most of the interdimer interactions increase.

Journal Articles

Polarized neutron inelastic scattering study of the anisotropic magnetic fluctuations in quasi-one-dimensional ising-like antiferromagnet TlCoCl$$_{3}$$

Osawa, Akira*; Kakurai, Kazuhisa; Nishiwaki, Yoichi*; Kato, Tetsuya*

Journal of the Physical Society of Japan, 75(7), p.074719_1 - 074719_4, 2006/07

 Times Cited Count:6 Percentile:56.25(Physics, Multidisciplinary)

Polarized neutron inelastic scattering experiments have been carried out in the quasi-1D Ising-like antiferromagnet TlCoCl$$_{3}$$. We observed the longitudinal magnetic fluctuation S$$_{zz}$$(Q,$$omega$$) for the spin-wave excitation continuum for the first time, together with the transverse magnetic fluctuation S$$_{xx}$$(Q,$$omega$$). We compared both obtained intensities of S$$_{xx}$$(Q,$$omega$$) and S$$_{zz}$$(Q,$$omega$$) with the predictions of the perturbation theory from the pure Ising limit by Ishimura and Shiba.

Journal Articles

Pressure-induced magnetic quantum phase transition in gapped spin system KCuCl$$_{3}$$

Goto, Kenji; Fujisawa, Masashi*; Tanaka, Hidekazu*; Uwatoko, Yoshiya*; Osawa, Akira*; Osakabe, Toyotaka; Kakurai, Kazuhisa

Journal of the Physical Society of Japan, 75(6), p.064703_1 - 064703_7, 2006/06

 Times Cited Count:25 Percentile:24.52(Physics, Multidisciplinary)

Magnetization and neutron elastic scattering experiments under hydrostatic pressure were performed on KCuCl$$_{3}$$, which is a three-dimensionally coupled spin dimer system with a gapped ground state. It was found that the intradimer interaction decreases with increasing hydrostatic pressure, while the sum of the interdimer interactions increases. This leads to the shrinkage of the spin gap. A quantum phase transition from a gapped state to an antiferromagnetic state occurs at Pc$$sim$$8.2 kbar. For P$$>$$Pc, magnetic reflections were observed at reciprocal lattice points equivalent to those for the lowest magnetic excitation at zero temperature. This confirms that the spin gap decreases and closes under applied pressure.

Journal Articles

Experimental and theoretical elastic cross sections for electron collisions with the C$$_{3}$$H$$_{6}$$ isomers

Makochekanwa, C.*; Kato, Hidetoshi*; Hoshino, Masamitsu*; Tanaka, Hiroshi*; Kubo, Hirotaka; Bettega, M. H. F.*; Lopes, A. R.*; Lima, M. A. P.*; Ferreira, L. G.*

Journal of Chemical Physics, 124(2), p.024323_1 - 024323_9, 2006/00

 Times Cited Count:15 Percentile:51.14(Chemistry, Physical)

no abstracts in English

Oral presentation

Magnetization and neutron scattering experiments on TlCuCl$$_{3}$$ and KCuCl$$_{3}$$ under applied pressure

Goto, Kenji*; Fujisawa, Masashi*; Osawa, Akira*; Kakurai, Kazuhisa; Osakabe, Toyotaka; Uwatoko, Yoshiya*; Tanaka, Hidekazu*

no journal, , 

no abstracts in English

Oral presentation

Longitudinal fluctuation in the spin-wave continuum of ising-like antiferromagnetic chain system TlCoCl$$_{3}$$

Kakurai, Kazuhisa; Osawa, Akira*; Nishiwaki, Yoichi*; Kato, Tetsuya*

no journal, , 

We report the results of polarized neutron inelastic scattering experiments on the quasi-one dimensional Ising-like antiferromagnet TlCoCl$$_{3}$$. The longitudinal spin fluctuation in the spin-wave excitation continuum has been clearly identified. The observed longitudinal fluctuation together with the transverse fluctuation are compared with the predictions of the perturbation theory from the pure Ising limit by Ishimura and Shiba.

Oral presentation

Neutron diffraction study on magnetic phase transition of RbCoBr$$_{3}$$

Nishiwaki, Yoichi*; Osawa, Akira*; Kakurai, Kazuhisa; Nakamura, Tota*; Todoroki, Norikazu*; Kuroe, Haruhiko*; Kato, Tetsuya*

no journal, , 

no abstracts in English

Oral presentation

The Study of trace elements migration at fault

Nagata, Hiroshi*; Honda, Teruyuki*; Iwatsuki, Teruki

no journal, , 

Trace elements analysis have been carryed out to estimate the migration property of fault zone at Horonobe area, Hokkaido. The results show that the light Ln elements are highly sorped on the clay minerals in fault zone.

Oral presentation

Lifetime-resolved H$$^{*}$$ fluorescence following O(1s) excitation/ionisation in gas-phase water molecules

Harries, J.; Gejo, Tatsuo*; Sullivan, J. P.*; Azuma, Yoshiro*

no journal, , 

In this research we have obtained new information on the photo-dissociation dynamics of the water molecule following O (1s) inner-shell excitation/ionisation. When the O 1s electron is excited neutral excited H atoms can be produced. By investigating which states these H atoms are information can be obtained on the dissociation routes. When the inner-shell O 1s electron is excited/ionises, an unstable H$$_2$$O$$^+$$ ion core is formed. This is unstable, and Auger decay occurs. The resulting H$$_2$$O$$^{2+}$$ ion core dissociates, and one of the fragments can capture the initially excited electron. When this fragment is H$$^+$$, a neutral H atom is formed. In this research we use the pulsed nature of synchrotron radiation to study the lifetimes of the fluorescing excited states produced.

Oral presentation

Performance verification test of NbTi joint for JT-60SA EF coil

Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Takahata, Kazuya*; Hamaguchi, Shinji*; Yanagi, Nagato*; Imagawa, Shinsaku*; Mito, Toshiyuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

Stability evaluation of joint in JT-60SA central solenoid

Kawahara, Yuzuru*; Yamamoto, Yusuke*; Nakamura, Kazuya*; Takao, Tomoaki*; Yagai, Tsuyoshi*; Murakami, Haruyuki; Yoshida, Kiyoshi; Natsume, Kyohei*; Hamaguchi, Shinji*; Obana, Tetsuhiro*; et al.

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)