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Ibi A.,SRL ISTEC | Miyata S.,SRL ISTEC | Taneda T.,SRL ISTEC | Yoshizumi M.,SRL ISTEC | And 9 more authors.
Physics Procedia | Year: 2013

We have been developing long REBa2Cu3O 7-δ coated conductors with high performance by the combination of the IBAD and the PLD methods. To realize the low production cost for REBa2Cu3O7-δ coated conductors, growth conditions were optimized for long tape fabrication in the in-plume PLD method . As a result, the Ic performance was confirmed with a high production rate under the high oxygen gas pressure and high laser energy density of > 800 mTorr and > 3 J/cm2, respectively. We successfully fabricated a 35 m long GdBa2Cu3O7-δ coated conductor with high Ic value of 619 A/cm-w by the production rate of 30 m/h. © 2013 The Authors.


Shiohara K.,Kyushu University | Higashikawa K.,Kyushu University | Kawaguchi T.,Kyushu University | Inoue M.,Kyushu University | And 3 more authors.
Physica C: Superconductivity and its Applications | Year: 2011

We have carried out 2-dimensional (2D) measurement of local critical current in a Trifluoroacetates-Metal Organic Deposition (TFA-MOD) processed YBCO coated conductor using scanning Hall-probe microscopy. Recently, remarkable R&D accomplishments on the fabrication processes of coated conductors have been conducted extensively and reported. The TFA-MOD process has been expected as an attractive process to produce coated conductors with high performance at a low production cost due to a simple process using non-vacuum equipments. On the other hand, enhancement of critical currents and homogenization of the critical current distribution in the coated conductors are definitely very important for practical applications. According to our measurements, we can detect positions and spatial distribution of defects in the conductor. This kind of information will be very helpful for the improvement of the TFA-MOD process and for the design of the conductor intended for practical electric power device applications. © 2011 Elsevier B.V. All rights reserved.


Shiohara K.,Kyushu University | Higashikawa K.,Kyushu University | Inoue M.,Kyushu University | Kiss T.,Kyushu University | And 4 more authors.
Physica C: Superconductivity and its Applications | Year: 2013

We have investigated electric field criterion of in-plane critical current density in a coated conductor characterized by scanning Hall-probe microscopy (SHPM). From remanent field distribution and its relaxation measurements, we could obtain critical current distribution and induced electric field simultaneously by considering the Biot-Savart law and the Faraday's law, respectively. These results lead us to evaluate a distribution of local critical current density and the corresponding criterion of electric field. As a result, it was found that the electric field criterion for the SHPM analysis was several orders lower than that used in the conventional 4-probe resistive method. However, the data point obtained by the SHPM shows good agreement with E-J curve analytically extended from the measurements by the 4-probe method. This means that we could characterize in-plane distribution of critical current density in a coated conductor at an electric field criterion quantitatively by this method in a nondestructive manner. These findings will be very important information since the uniformity of local critical current density in a coated conductor at extremely low electric fields is a key issue (1) especially for DC applications, (2) for quality control of coated conductors, and (3) for the standardization of the characterization of critical current among different methods.


Adachi S.,SRL ISTEC | Tsukamoto A.,SRL ISTEC | Moon Y.,SRL ISTEC | Oshikubo Y.,SRL ISTEC | Tanabe K.,SRL ISTEC
2015 15th International Superconductive Electronics Conference, ISEC 2015 | Year: 2015

We have fabricated high-Tc SQUIDs consisting of ramp-edge-type Josephson junctions and oxide multilayer structures. Preparation of a superconducting layer with c-axis orientation on ramp-surfaces is one of key issues. We report transmission electron microscope (TEM) study of the La0.1Er0.95Ba1.95Cu3Oy(L1ErBCO) layer prepared by a pulsed laser deposition (PLD) method on ramp-surfaces made of SrSnO3(SSO) and SmBa2Cu3Oy(SmBCO). Inclusion of grains with aaxis orientation was seen in L1ErBCO on SSO. After observation of various samples, we found a tendency that the number of aoriented grains was reduced by depositing L1ErBCO on shallower ramps. On the other hand, successful growth of the layer with c-axis orientation was observed in the L1ErBCO layer on the SmBCO ramp, suggesting that the SmBCO promoted the c-axis growth of L1ErBCO. Electron diffraction indicated that in-plane orientation was also achieved for the L1ErBCO grains on SmBCO. © 2015 IEEE.


Tsukamoto A.,SRL ISTEC | Hato T.,SRL ISTEC | Adachi S.,SRL ISTEC | Motoori M.,Japan Oil, Gas and Metals National Corporation | And 2 more authors.
2015 15th International Superconductive Electronics Conference, ISEC 2015 | Year: 2015

We have developed a magnetic prospecting system with HTS SQUID gradiometers for exploration of metal resources. The SQUID gradiometer consists of a flux transformer chip made of a YBCO thin film and a SQUID gradiometer chip which is stacked on the transformer chip. The SQUID gradiometer chip was fabricated by using an HTS multilayer and ramp-edge junction technology at ISTEC. Their effective volume and the balance estimated by using a Helmholtz coil were approximately 3 x 10-9 m3 and 1/500, resulting in the gradiometric field noise of 7 pT/m/Hz1/2 at 10 Hz. Two assembled SQUID gradiometers which measure dBz/dx and dBz/dy field gradients were cooled with liquid nitrogen in a cryostat of the magnetic prospecting system. The cryostat was suspended from the frame of the system and its attitude was self-controlled by gravity. The magnetic prospecting system with the HTS SQUID gradiometers, flux-gate sensors, a GPS module, and a gyro sensor was also tested in a field near an old mine. © 2015 IEEE.

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