2007 Fiscal Year Final Research Report Summary
Development of low- lossAg-sheathed superconducting tapes based on electromagnetic design and their application to AC power cables
| Project/Area Number |
17206026
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電力工学・電気機器工学
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
OOTA Akio Toyohashi University of Technology, Department of Electrical and Electronic Engineering, Professor (10124728)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Yuichi Toyohashi University of Technology, Department of Electrical and Electronic Engineering, Associate Professor (20345953)
INADA Ryoji Toyohashi University of Technology, Departmatt of Bechical and Electronic Engineering, Assistant Professor (30345954)
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| Project Period (FY) |
2005 – 2007
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| Keywords | High-Tc superconductors / Ag-sheathed superconducting tapes / cable conductors / low-loss wires / AC lossees / electromagnetic design / resistive barriers / filament twist |
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| Research Abstract |
Studies on development of low-loss Ag-sheathed superconducting tapes based on electromagnetic design and their application to AC power cables have been conducted for three years between fiscal 2005 and 2007. Main results through the study am summarized as follows:
(1) Construction of AC loss measurement system
We constructed the measuring system to obtain the AC losses generating in superconducting tape under AC operation, in passing through AC transport current and AC external magnetic fields at arbitrary directions to tape surface. Using this, we can obtain total values of AC losses obtained by a sum of AC transport losses and AC magnetization losses in the tapes and/or wires, while changing frequency, transport current amplitude and magnetic field amplitude.
(1) Fabrication and characterization of Ag-sheathed high-Tc superconductiong tapes with interfilamentary resistive barriers
We successfully fabricated Ag-sheathed high-Tc superconducting tapes with interflamaaary resistive barriers
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and investigated their electromagnetic properties toward applications to electric power cables. We used two methods for banier introduction in tape fabrication. The one is the coating method using paste of resistive barriers and another the inner oxidization method using metals with nice mechanical properties. In particular the tape fabrication using mixture of Ca_2CuO_3 powder and 30 wt%Bi2212 powder as barrier materials produces Ag-sheathed tapes on the order of several meter lengths, which have considerable nice and homogeneous J,(77K, OT) distribution well above 10^4 A/cm2 (1.8 x 10^4A/cm2 at maximum). In addition, this barrier introduction causes several-times enhancement in transverse resistively and lowers the AC losses up to 1/3 compared to the tapes without barrier introduction.
(2) Electric fields andAC losses for cylindrical conductor cables composed of Ag-sheathed superconducting tapes
We elucidate the electric-field distribution near cylindrical conductor cables composed of Ag-sheathed superconducting tapes based on the electromagnetic theory, which plays an important role in the error estimation for AC losses from measurements. The electric field under AC operation shows complicated variations in the vicinity of cables depending upon the cable structures and it becomes nearly constant in going away from the tape surface by about tape width. The result shows that AC loss measurements for cable conductors should be made at the distance far from the tape surface by at least tape width Less
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