Securing reversibility of UO/UOredox equilibrium in [emim]TfN-based liquid electrolytes towards uranium redox-flow battery

Takao, Koichiro*; Ouchi, Kazuki; Komatsu, Atsushi; Kitatsuji, Yoshihiro; Watanabe, Masayuki

European Journal of Inorganic Chemistry, 27(14), p.e202300787_1 - e202300787_7, 2024/05

https://doi.org/10.1002/ejic.202300787

Electrochemical behavior of UO/UO in 1-ethyl-3-methylimidazolium bis(trifluoromethyl)sulfonylamide ([emim]TfN) ionic liquid was studied to clarify what are required to attain its redox reversibility for utilizing depleted U as an electrode active material in a redox flow battery. As a result, reversibility of the UO/UO redox reaction was successfully achieved in use of a glassy carbon working electrode under presence of Cl in [emim]TfN. To improve diffusivity of solutes, [emim]TfN diluted with an auxiliary molecular solvent, N,N-dimethylformamide (DMF). We have succeeded in demonstrating a reversible redox reaction of [UOCl] + e = [UOCl] in the 50:50 v/v [emim]TfN-DMF liquid electrolyte containing Cl.

Factors influencing the fluctuation amplitude of the H ion beam extracted from an RF wave excited ion source plasma

Wada, Motoi*; Shibata, Takanori*; Shinto, Katsuhiro

Journal of Physics; Conference Series, 2743, p.012031_1 - 012031_5, 2024/05

https://doi.org/10.1088/1742-6596/2743/1/012031

An internal antenna type RF driven negative hydrogen (H) ion source supplies beams to the J-PARC accelerator facility. The H ion beam current exhibits high stability, while it fluctuates with less than 5% amplitude of the DC current when a Faraday cup measures the current extracted from the source mounted on a test stand. Two frequencies are identified as the main oscillation components, 2 MHz and 4 MHz which are the driving RF frequency and the second harmonics, respectively. The amplitude levels of these components appear larger as parts of the beam directing specific angles passing through a slit are detected. A possible reason for observing a small amplitude oscillation in the total beam intensity is the averaged phase-shift of the local beam depending upon the position of the H ion production and the succeeding trajectory reaching the Faraday cup. To confirm if the phase-shift is the main reason for diminishing the oscillation amplitude for the total beam, the phase-shift between the 2 MHz and 4 MHz components were measured for beams passing through a 0.1 mm slit coupled to a Faraday cup having a 0.1 mm entrance slit. The result indicated the phase-shift changed substantially depending upon the position, but no simple model can explain the measured spatial distribution of the phase-shift. Further attempts will be made to clarify the beam dynamics relevant to the H ion beam transport including the measurements of the beam current phase-shift with respect to the RF antenna current, and the time evolution of Balmer- light emission.

Development of standard substance for hydrogen analysis in materials

Ogawa, Hiroaki; Ishikawa, Norito

2023-Nendo Daigaku Kenkyu Josei Gijutsu Kenkyu Hokokusho, p.123 - 134, 2024/03

Evaluation of corrosion and hydrogen embrittlement is important in the quality control of stainless steel and the development of next steel materials assuming a high-pressure hydrogen environment. Typically, a secondary ion mass spectrometer (SIMS) is used to analyze hydrogen in steel materials. The hydrogen concentration of conventional standard substance for hydrogen analysis is as small as 1wt-ppm, which has been a problem in hydrogen analysis. We use a hydrogen-implant method to create a locally higher hydrogen concentration than that of the conventional. Hydrogen concentration analysis has been evaluated using the nuclear reaction analysis (NRA) method at a tandem accelerator. We have succeeded in creating a sample with a higher hydrogen concentration of about 1,900 wt-ppm than that of the conventional in locally.

Ion tracks and nanohillocks created in natural zirconia irradiated with swift heavy ions

Ishikawa, Norito; Fukuda, Shoma; Nakajima, Toru; Ogawa, Hiroaki; Fujimura, Yuki; Taguchi, Tomitsugu*

Materials, 17(3), p.547_1 - 547_21, 2024/02

https://doi.org/10.3390/ma17030547

Natural monoclinic zirconia (baddeleyite) was irradiated with 340-MeV Au ions, and the irradiation-induced nanostructures (i.e., ion tracks and nanohillocks) were observed using transmission electron microscopy. The diameter of the nanohillocks is approximately 10 nm, which is similar to the maximum molten region size calculated using the analytical thermal spike model. Ion tracks are imaged as strained regions that maintain their crystalline structure. The cross-sections of most of the ion tracks are imaged as parallelopiped or rectangular contrasts as large as 10 nm. These results strongly indicate that the molten region is recrystallized anisotropically, reflecting the lattice structure. Furthermore, low-density track cores are formed in the center of the ion tracks. The formation of low-density track cores can be attributed to the ejection of molten matter toward the surface.

Discoloration of RF antenna coil surface after long-term operation of J-PARC ion source

Shibata, Takanori*; Shinto, Katsuhiro; Nammo, Kesao*; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Oguri, Hidetomo; Ishida, Masaki*; Wada, Motoi*

Journal of Instrumentation (Internet), 19, p.C01009_1 - C01009_8, 2024/01

https://doi.org/10.1088/1748-0221/19/01/C01009

From Nov. 2020 to Apr. 2021, the continuous ion source operation for 3,651 hours (5 months) was achieved. As the lifetime of the RF ion source is mainly limited by failure on the enamel coating of the RF antenna, detailed evaluation of the antenna surface is required to ensure feasibility of the further extension of the operation time. In the present study, surface discoloration on the RF antenna coil observed after the 5 months operation is investigated by application of digital microscope and SEM/EDS analyses. The material mapping and the line spectrum obtained by the EDS analysis show that depositions of the sputtered source chamber wall materials and the injected cesium on to the enamel coating are the most possible candidate for the discoloration. The dimension measurements of the RF antenna thickness before and after the long-term operation support the idea that the discoloration is due to the deposited materials and hence insulation of the RF antenna coil by enamel coating is maintained. The emittance measurement after the operation also shows that the RF plasma and the beam formations are not affected by the deposition on the antenna.

Comparative study of the underpotential deposition of Bi in an aqueous electrolyte and an ionic liquid

Tamura, Kazuhisa

Journal of Physical Chemistry C, 127(46), p.22733 - 22739, 2023/11

https://doi.org/10.1021/acs.jpcc.3c05404

The underpotential deposition of Bi on Au(111) electrode in 1 M HClO solution and 1-butyl-3-methylimidazolium tetrafluoroborate was investigated using visible light reflectance measurement and surface X-ray scattering techniques. The electrosorption valency of the UPD reaction of Bi was elucidated and it was found that in both 1 M HClO and 1-butyl-3-methylimidazolium tetrafluoroborate the electrosorption valency was smaller than 3, but the detail process in the UPD reaction was different between in two electrolytes. The difference may be originated from the difference in the solvation status of Bi rather than the electrical double layer structure.

Operation status of the J-PARC high-intensity RF-driven negative hydrogen ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Kawai, Isao*; Ikegami, Kiyoshi*; Ueno, Akira

Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.928 - 931, 2023/11

https://www.pasj.jp/web_publish/pasj2023/proceedings/PDF/FRP3/FRP35.pdf

J-PARC initiated the operation of the high-intensity rf-driven negative hydrogen (H) ion source in 2014 autumn. The ion source produces the H beam with the beam current of 60 mA and the beam energy of 50 keV in order to inject the H beam into the 3 GeV RCS with the beam current of 50 mA and the beam energy of 400 MeV from the J-PARC linac. We have achieved the longest continuous operation time of 4001 hours in the previous (2021/2022) campaign. The 2022/2023 campaign was the first time that the continuous operation of the H ion source without any exchanges of the ion source until the end of the campaign was examined. We present the operation status of the J-PARC H ion source in this campaign as well as the status of the J-PARC-made internal antenna test.

In-operando distribution measurement of internal temperature and stress in lithium-ion battery

Hirano, Tatsumi*; Maeda, Takehiro*; Murata, Tetsuyuki*; Yamamoto, Takahiro*; Matsubara, Eiichiro*; Shobu, Takahisa; Shiro, Ayumi*; Yasuda, Ryo*; Takamatsu, Daiko*

SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 11(5), p.345 - 353, 2023/10

https://doi.org/10.18957/rr.11.5.345

no abstracts in English

An X-ray and neutron scattering study of aqueous MgCl solution in the gigapascal pressure range

Yamaguchi, Toshio*; Fukuyama, Nami*; Yoshida, Koji*; Katayama, Yoshinori*; Machida, Shinichi*; Hattori, Takanori

Liquids, 3(3), p.288 - 302, 2023/09

https://doi.org/10.3390/liquids3030019

We report the structure of an aqueous 2 mol/kg MgCl solution at pressures from 0.1 MPa to 4 GPa and temperatures from 300 to 500 K revealed by X-ray and neutron scattering measurements. The scattering data are analyzed by empirical potential structure refinement (EPSR) modeling to derive the pair distribution functions, coordination number distributions, angle distributions, and spatial density functions as a function of pressure and temperature. Mg forms rigid solvation shells extended to the third shell; the first solvation shell of six-fold octahedral coordination with about six water molecules at 0 GPa transforms into about five water molecules and one Cl due to the formation of the contact ion pairs in the GPa pressure range. The Cl solvation shows a substantial pressure dependence; the coordination number of a water oxygen atom around Cl increases from 8 at 0.1 MPa/300 K to 10 at 4 GPa/500 K. The solvent water transforms the tetrahedral network structure at 0.1 MPa/300 K to a densely packed structure in the GPa pressure range; the number of water oxygen atoms around a central water molecule gradually increases from 4.6 at 0.1 MPa/298 K to 8.4 at 4 GPa/500 K.

Proceedings of the 34th Meeting for Tandem Accelerators and their Associated Technologies

Kabumoto, Hiroshi; Nakagawa, Sohei; Matsuda, Makoto

JAEA-Conf 2022-002, 146 Pages, 2023/03

JAEA-Conf-2022-002.pdf:9.89MB

"The 34th Meeting for Tandem Accelerators and their Associated Technologies" was held on July 21-22, 2022 organized by Nuclear Science Research Institute of the Japan Atomic Energy Agency. This meeting was held only on-line for preventing the spread of COVID-19 infection. The purpose of this meeting is contribution of development for related technology and of management of facilities through exchange of information among the researchers and engineers using and operating electrostatics accelerator facilities like tandem accelerators. There were 25 presentations which contains current status report of facility, technical development of accelerator, research of application. The total number of participants was a hundred, from 26 universities, research organizations and industries. This meeting consisted of only oral session, a poster session was not carried out because of on-line meeting. This proceeding compiles the contents of report papers in the meeting.