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Journal Articles

Evaluation of bending strain in Nb$$_{3}$$Sn strands of CIC conductor using neutron diffraction

Hemmi, Tsutomu*; Harjo, S.; Kajitani, Hideki*; Suwa, Tomone*; Saito, Toru*; Aizawa, Kazuya; Osamura, Kozo*; Koizumi, Norikiyo*

IEEE Transactions on Applied Superconductivity, 27(4), p.4200905_1 - 4200905_5, 2017/06

Journal Articles

Uniaxial strain dependence of the critical current of DI-BSCCO tapes

Osamura, Kozo*; Machiya, Shutaro*; Hampshire, D. P.*; Tsuchiya, Yoshinori*; Shobu, Takahisa; Kajiwara, Kentaro*; Osabe, Goro*; Yamazaki, Kohei*; Yamada, Yuichi*; Fujikami, Jun*

Superconductor Science and Technology, 27(8), p.085005_1 - 085005_11, 2014/08

 Times Cited Count:20 Percentile:24.82(Physics, Applied)

Journal Articles

Residual strains in ITER conductors by neutron diffraction

Harjo, S.; Hemmi, Tsutomu; Abe, Jun; Gong, W.; Nunoya, Yoshihiko; Aizawa, Kazuya; Ito, Takayoshi*; Koizumi, Norikiyo; Machiya, Shutaro*; Osamura, Kozo*

Materials Science Forum, 777, p.84 - 91, 2014/02

 Times Cited Count:2 Percentile:17.26

Journal Articles

Investigation of degradation mechanism of ITER CS conductor sample using TAKUMI

Hemmi, Tsutomu; Harjo, S.; Kajitani, Hideki; Nabara, Yoshihiro; Takahashi, Yoshikazu; Nunoya, Yoshihiko; Koizumi, Norikiyo; Abe, Jun; Gong, W.; Aizawa, Kazuya; et al.

KEK Progress Report 2013-4, p.45 - 47, 2013/11

The gradual degradation was observed in the results for ITER CS conductor samples. To investigate its origin, the internal strain in the sample after the testing was successfully measured using a neutron diffraction technique non-destructively. Up to now, the transverse electromagnetic loading has been considered as an origin of the degradation due to the local bending at the high loading side (HLS). However, as a result of the neutron diffraction measurement, the large bending at the LLS of the HFZ was found. The large bending was considered as an origin of the strand buckling due to the large void generated by the transverse electromagnetic loading and the thermally induced residual compressive strain. For the improvement of the conductor performance on the strand buckling, the shorter twisting pitch (STP) can be considered. The result of the SULTAN testing of the conductor sample with STP found very effective, and the performance degradation was negligible.

Journal Articles

Neutron diffraction measurement of internal strain in the first Japanese ITER CS conductor sample

Hemmi, Tsutomu; Harjo, S.; Nunoya, Yoshihiko; Kajitani, Hideki; Koizumi, Norikiyo; Aizawa, Kazuya; Machiya, Shutaro*; Osamura, Kozo*

Superconductor Science and Technology, 26(8), p.084002_1 - 084002_6, 2013/08

 Times Cited Count:14 Percentile:37.28(Physics, Applied)

JAEA has responsibly to procure all ITER CS conductors. Several conductor samples was fabricated and tested. From the result of the cyclic testing in first conductor sample named JACS01 and second conductor sample named JACS02, the continuous linear degradation of the current sharing temperature ($$T$$$$_{cs}$$) was observed. To investigate the $$T$$$$_{cs}$$ degradation, the visual inspection of JACS01 right leg was performed. As a result, the large deflection at the lower loading side (LLS) in the high field zone (HFZ) was observed. The bending strain of the strands cannot be evaluated from the only deflection obtained by a visual inspection. To evaluate the strain of strands in the conductor sample quantitatively, the neutron diffraction measurement of JACS01 left leg was performed using the engineering materials diffractometer in J-PARC. From the result, the large bending strain at the LLS in the HFZ was observed. Therefore, the degraded position in the conductor sample can be determined.

Journal Articles

Local strain and its influence on mechanical-electromagnetic properties of twisted and untwisted ITER Nb$$_{3}$$Sn strands

Osamura, Kozo*; Machiya, Shutaro*; Tsuchiya, Yoshinori*; Suzuki, Hiroshi; Shobu, Takahisa; Sato, Masugu*; Hemmi, Tsutomu; Nunoya, Yoshihiko; Ochiai, Shojiro*

Superconductor Science and Technology, 25(5), p.054010_1 - 054010_9, 2012/05

 Times Cited Count:13 Percentile:42.93(Physics, Applied)

Journal Articles

Neutron diffraction measurements of internal strain in Nb$$_{3}$$Sn cable-in-conduit conductors

Hemmi, Tsutomu; Harjo, S.; Ito, Takayoshi; Matsui, Kunihiro; Nunoya, Yoshihiko; Koizumi, Norikiyo; Takahashi, Yoshikazu; Nakajima, Hideo; Aizawa, Kazuya; Suzuki, Hiroshi; et al.

IEEE Transactions on Applied Superconductivity, 21(3), p.2028 - 2031, 2011/06

 Times Cited Count:8 Percentile:50.4(Engineering, Electrical & Electronic)

Residual strain in conductors is caused by the difference in the coefficient of expansion between Nb$$_{3}$$Sn strands and the jacket over a temperature range of 5 - 923 K. The superconducting properties of strands vary significantly, depending on the strain. It is important to clarify the residual strain as part of the evaluation of superconducting performance. However, the residual strain of strands in the conductor has not been measured so far because of their complicated configuration and their location in a jacket. The engineering materials diffractometer "Takumi" in J-PARC can measure residual strain with a relative accuracy of around 0.02%, using neutron diffraction. In this study, the Takumi was applied to the measurement of residual strain in strands for the ITER TF conductor. Results indicate that the residual strain of strands in the conductor can be determined, thereby clarifying the mechanism of residual strain and its relationship to superconducting performance.

Journal Articles

Stress/strain effects on industrial superconducting composites

Ito, Takayoshi; Harjo, S.; Osamura, Kozo*; Hemmi, Tsutomu; Awaji, Satoshi*; Machiya, Shutaro*; Oguro, Hidetoshi*; Nishijima, Gen*; Takahashi, Koki*; Matsui, Kunihiro; et al.

Materials Science Forum, 681, p.209 - 214, 2011/05

 Times Cited Count:1 Percentile:37.84

Journal Articles

Force free strain exerted on a YBCO layer at 77 K in surround Cu stabilized YBCO coated conductors

Osamura, Kozo*; Machiya, Shutaro*; Tsuchiya, Yoshinori*; Suzuki, Hiroshi

Superconductor Science and Technology, 23(4), p.045020_1 - 045020_7, 2010/04

 Times Cited Count:21 Percentile:29.94(Physics, Applied)

The stress/strain behavior of the surround Cu stabilized YBCO coated conductors and its influence on critical current were precisely investigated. The internal strain exerted on the superconducting YBCO layer was determined at 77 K by using a neutron diffraction technique at JAEA. The initial compressive strain decreased during tensile loading and changed to a tensile component at the force free strain (A$$_{rm ff}$$), where the internal uniaxial stress becomes zero in the YBCO layer. The A$$_{rm ff}$$ was evaluated to be 0.19-0.21% at 77 K. The critical current measurements were carried out under a uniaxial tensile load at 77 K. The strain dependence revealed a characteristic behavior, where a maximum was observed at 0.035%. Thus it was made clear that the strain at the critical current maximum does not correlate with A$$_{rm ff}$$ for YBCO coated conductors.

Journal Articles

Development of a cryogenic load frame for a neutron diffractometer

Tsuchiya, Yoshinori*; Suzuki, Hiroshi; Umeno, Takahiro*; Machiya, Shutaro*; Osamura, Kozo*

Measurement Science and Technology, 21(2), p.025904_1 - 025904_4, 2010/01

 Times Cited Count:12 Percentile:29.3(Engineering, Multidisciplinary)

Strain measurements under loading at cryogenic temperatures are much requested for investigation of the stress/strain effect on the critical current for composite superconductors. In order to provide in-situ measurements of the lattice strain, a cryogenic load frame with a GM refrigerator has been developed, which is suitable for the neutron diffraction facility RESA equipped at JRR-3 in JAEA. The lowest temperature of 4.8 K was achieved, while the capacity of the load frame was 10 kN. Using the present cryogenic load frame, plane spacing measurement was performed under loading for two specified samples of 316 stainless steel and engineering YBCO coated conductor. The relation between applied stress/strain and lattice strain has been made clear in a wide range of temperatures.

Journal Articles

Precise study of vortex structures in Nb by small-angle neutron scattering

Miyata, Seiki*; Osamura, Kozo*; Suzuki, Junichi

Journal of the Physical Society of Japan, 70(7), p.2098 - 2101, 2001/07

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Observation of magnetic flux distribution in type II superconductors by means of small angle neutron scattering

Osamura, Kozo*; Miyata, Seiki*; Furusaka, Michihiro*; Suzuki, Junichi

Oyo Butsuri, 65(4), p.367 - 371, 1996/00

no abstracts in English

Oral presentation

Strain measurements of superconducting filaments and Ag-alloy using neutron diffraction in Ag-sheathed Bi2223 tapes

Machiya, Shutaro; Osamura, Kozo*; Suzuki, Hiroshi; Shiota, Yoshinori*; Ayai, Naoki*; Hayashi, Kazuhiko*; Sato, Kenichi*

no journal, , 

In situ strain measurement was made for inner Bi2223 filaments and outer Ag alloy in the Ag-sheathed Bi2223 tapes using neutron diffraction. The residual strain and the strain response under the axial tensile loading were measured in the Ag-sheathed Bi2223 tapes stacked with 10 sheets.

Oral presentation

Strain measurements of superconducting filaments and Ag-alloy using neutron diffraction in Ag-sheathed BSCCO Bi2223 tapes

Machiya, Shutaro; Osamura, Kozo*; Suzuki, Hiroshi; Ayai, Naoki*; Hayashi, Kazuhiko*; Sato, Kenichi*; Kato, Takeshi*

no journal, , 

no abstracts in English

Oral presentation

Residual stress estimation of Ag-sheathed Bi2223 tapes using Neutron and X-ray diffraction

Machiya, Shutaro; Osamura, Kozo*; Suzuki, Hiroshi; Ayai, Naoki*; Kato, Takeshi*; Hayashi, Kazuhiko*; Sato, Kenichi*

no journal, , 

no abstracts in English

Oral presentation

Strain measurements plan of the qualification sample for ITER CS using neutron diffraction

Hemmi, Tsutomu; Matsui, Kunihiro; Hase, Takashi*; Koizumi, Norikiyo; Takahashi, Yoshikazu; Okuno, Kiyoshi; Suzuki, Hiroshi; Harjo, S.; Aizawa, Kazuya; Tsuchiya, Yoshinori*; et al.

no journal, , 

JAEA is responsible for the procurement of the CS conductor of the ITER magnet system. In order to start the procurement of the CS conductor, the performance of the CS conductor have to be demonstrated. The qualification sample has been fabricated for the test using SULTAN apparatus at the Plasma Physics Research Centre (CRPP) of the Swiss Federal Institute of Technology of Lausanne (EPFL). In this presentation, the design and the fabrication of the qualification sample is reported. The residual strain should be controlled for the measurement of the correct performance. The neutron diffraction will be applied to the direct measurement of the strain of the superconducting cable. This plan is also presented.

Oral presentation

Residual strain estimation of CICC for ITER TF using neutron diffraction

Machiya, Shutaro*; Osamura, Kozo*; Hemmi, Tsutomu; Matsui, Kunihiro; Suzuki, Hiroshi; Tsuchiya, Yoshinori*

no journal, , 

no abstracts in English

Oral presentation

Engineering materials diffractometer "TAKUMI" and stress/strain effects on industrial superconducting composites

Harjo, S.; Aizawa, Kazuya; Ito, Takayoshi; Osamura, Kozo*; Awaji, Satoshi*; Hemmi, Tsutomu; Machiya, Shutaro*; Tsuchiya, Yoshinori*; Matsui, Kunihiro; Nishijima, Gen*

no journal, , 

no abstracts in English

Oral presentation

Neutron diffraction measurement of internal strain in ITER TF conductor

Hemmi, Tsutomu; Harjo, S.; Matsui, Kunihiro; Nunoya, Yoshihiko; Koizumi, Norikiyo; Nakajima, Hideo; Ito, Takayoshi; Aizawa, Kazuya; Suzuki, Hiroshi; Machiya, Shutaro*; et al.

no journal, , 

Residual strain in conductors is caused by the difference in the coefficient of expansion between strands and the jacket over a temperature range of 5 - 923 K. The properties of strands vary significantly, depending on the residual strain. It is important to clarify the residual strain as part of the evaluation of performance. However, the residual strain of strands in the conductor has not been measured so far because of their complicated configuration and their location in a jacket. The engineering materials diffractometer "Takumi" in J-PARC can measure residual strain using neutron diffraction. In this study, neutron diffraction using the Takumi was applied to the measurement of residual strain in strands for the ITER TF conductor. Results indicate that the residual strain of strands in the conductor can be determined, thereby clarifying the mechanism of residual strain and its relationship to performance.

Oral presentation

Neutron diffraction study of internal strain in Nb$$_{3}$$Sn Cable-In-Conduit Conductors

Hemmi, Tsutomu; Harjo, S.; Nunoya, Yoshihiko; Kajitani, Hideki; Koizumi, Norikiyo; Nakajima, Hideo; Aizawa, Kazuya; Machiya, Shutaro*; Osamura, Kozo*

no journal, , 

Internal strain in Cable-In-Conduit Conductors (CICC) is caused by differences in the coefficients of thermal expansion between Nb$$_{3}$$Sn strands and the stainless steel jacket over a temperature range of 5 - 923 K. In addition, transverse electromagnetic loading is generated by a current of 68 kA and a magnetic field of 11.8 T in the case of ITER TF coils. The performances of Nb$$_{3}$$Sn strands change significantly, depending on the presence of strain. The presence of internal strain in Nb$$_{3}$$Sn cables is important to evaluate the superconducting performance. However, the strain of strands in the conductor has not been measured so far because of the cabling configuration and their location in a jacket. Internal strain can be determined by neutron diffraction measurement using Takumi of J-PARC. Test results of the neutron diffraction and the role of the neutron diffraction measurement for the investigation of Tcs degradation of short conductor sample will be presented and discussed.

23 (Records 1-20 displayed on this page)