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Journal Articles

Improvement of J-PARC klystron high voltage power supply

Chishiro, Etsuji; Kawamura, Masato*; Sagawa, Ryu*; Ogawa, Shinichi*

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1091 - 1093, 2014/10

In J-PARC linac, six units of high voltage power supplies for 324 MHz klystrons have operated since 2006, and those running time exceed 35,000 hours. In addition, six units of power supplies for the 972 MHz klystrons have been operation since 2013. In the power supply, various troubles occur under the operation. In some anode modulators, arc discharge in the transformer oil had occurred due to the deterioration of the auxiliary solid insulator. In three modules combining a step-up transformer and a rectifier, the high voltage diode was breakdown because an unexpected overvoltage was applied. And by improving the voltage dividing resistor of the module, high stability cathode voltage was achieved. In this report, we describe the trouble and the improvement that occurred in the equipment.

Journal Articles

Present status of klystron power supply systems for J-PARC linac 2013

Kawamura, Masato*; Chishiro, Etsuji; Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*; Yamazaki, Masayoshi*; Sagawa, Ryu*; Miyajima, Noriyuki*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.605 - 607, 2014/06

This report describes the present status of the klystron power supply systems for the J-PARC linac. The systems for the 181 MeV linac were operated from September to May. A few breakdowns were occurred, and are described in this report. The new systems for the upgrade of the linac from 181MeV to 400 MeV have been installed until now, and the 3 HVDCPSs and the 3 anode modulators of the new systems have been operated. All the systems for 400 MeV linac will be operated in this autumn.

Journal Articles

Present status of klystron power supply systems for J-PARC linac 2012; Recovery from Earthquake Disaster, HVDCPS breakdown and energy upgrade

Kawamura, Masato*; Chishiro, Etsuji; Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*; Yamazaki, Masayoshi*; Sagawa, Ryu*; Yukitake, Mitsuteru*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1243 - 1247, 2013/08

no abstracts in English

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2011

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Nagaoka, Mika; et al.

JAEA-Review 2013-009, 195 Pages, 2013/06

JAEA-Review-2013-009.pdf:3.35MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2011 to March 2012. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in March 2011.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2010

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.

JAEA-Review 2012-015, 166 Pages, 2012/05

JAEA-Review-2012-015.pdf:3.53MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2010 to March 2011. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in 2011 March. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data exceeded the normal range of fluctuation by the accidental release was evaluated in the appendices.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2009

Sumiya, Shuichi; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.

JAEA-Review 2011-004, 161 Pages, 2011/03

JAEA-Review-2011-004.pdf:4.09MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2009 to March 2010. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes.

Journal Articles

Correlation between the averaged internal structure and the coercive force of neodymium-iron-boron (Nd-Fe-B) sintered magnets investigated by small-angle neutron scattering

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

Proceedings of 21st International Workshop on Rare-Earth Permanent Magnets and their Applications (REPM 2010), p.161 - 164, 2010/08

We performed small-angle neutron scattering (SANS) measurements of Nd-Fe-B sintered magnets to get information on the averaged internal microstructure of Nd-Fe-B sintered magnets including the interfacial structure which is a key parameter to achieve a high-coercivity Dy-free Nd-Fe-B sintered magnet. SANS patterns from the Nd-Fe-B sintered magnets measured with a two-dimensional detector of a small-angle neutron scattering spectrometer SANS-J-II in the research reactor JRR-3 were sensitive to the sintering and annealing condition of the samples. These results indicate that the SANS measurement is a promising tool to investigate the correlation between the coercivity and the internal microstructure of Nd-Fe-B sintered magnets.

Oral presentation

Simulation of the small-angle neutron scattering pattern of Nd-Fe-B sintered magnet

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

no abstracts in English

Oral presentation

Small-angle neutron scattering patterns and real-space image of Nd-Fe-B sintered magnets

Takeda, Masayasu; Suzuki, Junichi*; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

no abstracts in English

Oral presentation

Average internal structures of Nd-Fe-B sintered magnets studied by small-angle neutron scattering

Takeda, Masayasu; Suzuki, Junichi*; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

no abstracts in English

Oral presentation

Magnetization process of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets investigated by small-angle neutron scattering under external magnetic fields

Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Sagawa, Masato*

no journal, , 

The coercive force of Nd-Fe-B sintered magnets depends on several factors. Among those factors, the coercivity is easily affected by the temperature in the so-called low-temperature annealing process. A remarkable structural change of interface between the main phase (Nd$$_{2}$$Fe$${}_{14}$$B) and the Nd-rich phase is believed to occur at the temperature where the coercivity reaches the highest value. We performed the small-angle neutron scattering measurements to distinguish the SANS originating in nuclear structure from that in magnetic one. The external magnetic fields were applied parallel to the $$c$$-axis, and were increased up to 10 kOe every 2 kOe during the measurements. Quantitative analysis of the change of scattering patterns and the magnetization process is reported at the meeting.

Oral presentation

Correlation between the coercivity and the averaged internal structures of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets studied by small-angle neutron scattering measurements, 2

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

We have been investing the correlation between the coercive force and the averaged internal structure of Neodymium-Iron-Boron (Nd-Fe-B) sintered magnets using the small-angle neutron scattering (SANS) spectrometer, SANS-J-II installed at the beam hall of the research reactor JRR-3 in Tokai. The correlation is a clue to achieve the less or Dysprosium (Dy)-free Nd-Fe-B sintered magnets with high coercivity for high-temperature application. In this talk, we report that the coercivity is very sensitive to the averaged diameter of powder and the temperature in sintering process, and that the SANS patterns on 2-dimensional position-sensitive detector (2D-PSD) are also sensitively changed following the sintering condition.

Oral presentation

Characterization of average interface structure in sintered Nd-Fe-B magnets by small angle neutron scattering

Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Sagawa, Masato*; Koyama, Keiichi*

no journal, , 

no abstracts in English

Oral presentation

Polarized small-angle neutron scattering measurements of averaged internal structure in Nd-Fe-$$^{11}$$B sintered magnets

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Sagawa, Masato*; Koyama, Keiichi*

no journal, , 

Nd-Fe-B magnets are now widely used because of the highest BH$$_{rm max}$$ of them in the commercially available magnets. At the present, Dy, which is one of the rare metals, has to be added to maintain the coercivity especially in the operational temperatures higher than the room temperature. The key to achieve the Dy-free Nd-Fe-B magnets is how to control the grain size and the structure near the grain boundary. We have performed the small-angle neutron scattering (SANS) measurements of the sintered Nd-Fe-$$^{11}$$B magnets using unpolarized and polarized neutrons to obtain the averaged internal structures of samples with the different coercivity introduced by applying different high magnetic fields during the annealing. We found that inhomogeneity was induced by the magnetic fields applied parallel to $$vec{M}$$. The relation between the inhomogeneity and the coercivity force is unclear at the moment, but we will present possible interpretation.

Oral presentation

Study of averaged internal structures of Nd-Fe-B sintered magnets studied by small-angle neutron scattering

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

no abstracts in English

Oral presentation

Evaluation of averaged structures of sintered Nd-Fe-B magnets by small angle neutron scattering

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Akiya, Takahiro*; Kato, Hiroaki*; Sagawa, Masato*

no journal, , 

no abstracts in English

Oral presentation

Small angle neutron scattering study of interface nanostructure in sintered Nd-Fe-B magnets processed under high magnetic fields

Akiya, Takahiro*; Kato, Hiroaki*; Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Koizumi, Satoshi; Sagawa, Masato*; Koyama, Keiichi*

no journal, , 

Sintered Nd-Fe-B magnets are the most promising materials for a driving motor of the hybrid electric vehicles(HV). In this application, a large value of coecivity $$H_{c}$$ is required because of the high operating temperature beyond 450 K. As a symptomatic treatment, Nd has been replaced partly by Dy to enhance $$H_{c}$$. But the problem is an estimated short supply of Dy in the HV mass-production stage due to its low natural abundance. We have recently shown that $$H_{c}$$ of Nd-Fe-B magnets can be enhanced by applying a high magnetic field during the annealing. In order to elucidate the reason for the $$H_{c}$$ increase, we performed a small angle neutron scattering (SANS) study using SANS-J and PNO at JRR-3 of JAEA. We observed a marked deviation from the simple relation above for $$q > 0.3 nm^{-1}$$ in the sample with Al and Cu additives. SANS results suggest that an existence of the Cu-containing liquid phases is strongly correlated with the $$H_{c}$$ enhancement by the high field annealing.

Oral presentation

Study of the correlation between the coercivity and averaged internal structure of Nd-Fe-B sintered magnets

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

A neodymium iron boron (Nd-Fe-B) sintered magnet is the most powerful permanent magnet among the commercially available ones. Dysprosium (Dy), however, has to be added in Nd-Fe-B sintered magnets to keep the high $$H_{rm c}$$ above the room temperature or high-temperature applications. Dy-less or Dy-free Nd-Fe-B sintered magnets are now highly demanded because Dy is one of the rare metals. We performed small-angle neutron scattering (SANS) measurements of sintered Nd-Fe-B sintered magnets to elucidate the correlation between the coercivity and averaged internal structures of this magnet. Such correlation is a clue to achieve the Dy-less or Dy-free Nd-Fe-B sintered magnets. In this talk, we report the detailed results of the experiments and the correlation revealed by the SANS measurements.

Oral presentation

Simulation of small-angle neutron scattering pattern of Nd-Fe-B sintered magnets, 2

Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*; Takeda, Masayasu

no journal, , 

no abstracts in English

Oral presentation

Small-angle neutron scattering measurements of Nd-Fe-B sintered magnets, 2

Takeda, Masayasu; Suzuki, Junichi; Yamaguchi, Daisuke; Akiya, Takahiro*; Kato, Hiroaki*; Une, Yasuhiro*; Sagawa, Masato*

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)