YBCO coated conductors have been expected to be applied to superconducting magnetic energy storage (SMES) due to high critical current density under high magnetic field and possibility of reducing ...cooling cost. Solder joints are essential to fabricate a high T c superconducting coil for SMES system which requires long length of coated conductors. Not only low joint resistance but sufficient mechanical strength is needed, since conductors are exposed to large electromagnetic force generated by large transport current and high magnetic field. In the present study, influence of tensile load on transport property through the joint was investigated. The solder joint with sufficiently low resistance of 5.3 nOmega was attained before loading. Such joint can carry the load up to 650 N without substantial degradation. For further applied load, degradation attributed to fracture at the edge of the conductor is firstly observed. Overall fracture is caused by delamination at the interface between YBCO and CeO 2 . As a result, importance of interfacial strength between the superconducting and buffer layer is revealed to realize both low joint resistance and mechanical strength for solder joint.
End stage kidney disease (ESKD) patients are characterized to reduce bone strength due to disordering of calcium and phosphorous homeostasis. We demonstrate the use of Fourier transform infrared ...imaging and Raman spectroscopy to characterize bone quality in ESKD rats. Eleven-week male rats treated 5/6-nephrectomy and sham-operated rats were kept for 16 weeks, and then each femur was removed for measurements. We observe excess bone resorption compared to bone formation in ESKD rat, and bone mineral loss in endosteum is observed rather than in periosteum. We also find trabecular bone and epiphysis have a rapid turnover rate compared to cortical bone.
The strain dependence of T c and I c for the GdBCO coated conductor was measured at 77 and 4.2 K in magnetic fields. T c decreased with increasing applied tensile strain. For the I c measurements, ...the magnetic field was applied in the direction parallel to the c-axis (perpendicular to the tape surface). I c in fields was degraded with increasing strain, and the strain dependence of I c increased with increasing magnetic field. The ratio of the I c degradation at 4.2 K was smaller than that at 77 K. These results mean that the T c degradation is one of the reasons for I c degradation at 77 K at least. Further, in order to understand the strain effect at 4.2 K, the internal strain of the GdBCO coated conductor under tensile strain was measured using synchrotron radiation. It was found that the strain behavior for the a-axis is different from that for the b-axis. This result suggests that the strain dependence of I c for GdBCO coated conductors under external tensile strain is related with the T c degradation behavior of the crystal.
GdBa 2 Cu 3 Oy coated conductors were annealed under external strain (strain-annealing). The residual strain after annealing was evaluated using synchrotron radiation. We found that the residual ...strain is changed by the strain-annealing. The volume fraction of the a-axis domains along the longitudinal direction is increased by compression-annealing and decreased by tension-annealing. In addition, the J c value of the tension-annealed sample increases drastically below 70 K, although the J c value is smaller than that of the as-received sample at 77.3 K for B//c. The peak of the angular dependent J c at θ = 0 ° , which originates from the c-axis correlated pinning, for the strain-annealed sample is much smaller than that of the as-received sample. It is considered that the shrinking of the c -axis correlated pinning because of the reduction of the twin structure and the increase of carrier doping may be related to the change in J c properties.
► The V-I curve shifted to lower current region, and the critical current and n-value decreased with increasing extent of cracking. ► The measured V-I curves, critical currents and n-values of local ...sections at various stresses were well described by the model of Fang et al. ► The relation of overall V-I curve, critical current and n-value to the local ones was described comprehensively with a voltage summation approach.
Under applied strain/stress, extent of damage varies with location in a sample. Accordingly, overall critical current and n-value of a sample depend on extent of damage of local sections. The present work aimed to reveal the correlation of critical current and n-value of overall sample to those of local sections in DyBCO coated conductor. Critical current and n-value were measured for the voltage probe distances 45 and 15mm, respectively, at 77K in a self magnetic field. Both critical current and n-value beyond irreversible strain (≈0.32%, corresponding to stress 320MPa) decreased significantly with applied strain/stress. The reason for this was accounted for by the increase in crack size, accompanied by increase in shunting current. While the local critical current and n-value were different from section to section due to the difference in extent of damage, the relation of overall critical current and n-value to the local ones was described comprehensively by combining the Fang model with a voltage summation approach.
Generally speaking for a HTS coil, perpendicular magnetic field to conductor's broad surface should be suppressed as small as possible in relation to the magnetic anisotropy. This is a reason why ...toroidal coil with relatively many elementary coils is expected for HTS-SMES. On the other hand, from the point of view of the homogenization of critical current distribution in the coil, perpendicular field and parallel field should be balanced corresponding to the ratio of the magnetic anisotropy. This means that a certain level of the perpendicular field is effective to reduce local heat generation in the coil. Furthermore, this concept is especially reasonable for a high-field coil with usual winding method (flat-wise winding) because the perpendicular field does not induce hoop stress which decreases the critical current. In this paper, we show these findings through an optimal design of a MOCVD-YBCO toroidal coil for 2 GJ class SMES taking account of magnetically and mechanically influenced J - E characteristics.
A superconducting magnet system for a new muonium hyperfine structure, MuHFS, measurement at J-PARC is being developed. This experiment requires a magnetic field strength of 1.7 T with high ...homogeneity below 1 ppm. The overall mechanical design including helium and vacuum vessels was almost completed. In order to evaluate the influence of coil vibration on the error field, the modal analysis was performed. The conceptual design of superconducting shim coils was carried out. The zonal and radial shim coils were designed by using the conventional spherical harmonics method and the singular value decomposition method, respectively.
► Crack-induced current shunting in coated conductor. ► Shunting current is enhanced by crack evolution. ► It increases with increasing voltage, leading to a decrease in
n-value at high voltage. ► ...Crack evolution- and voltage-dependence of transport current is described by modeling analysis.
Transport current and
n-value of DyBCO-coated conductor pulled in tension were measured experimentally and their relation to crack-induced current shunting was analyzed with the partial crack-current shunting model. The following features were revealed. The shunting current increases with increasing transport current and with increasing crack size. At low voltage where shunting current is low, the transport current of cracked sample normalized with respect to the transport current in non-cracked state is described with the modified ratio of non-cracked area to overall cross-sectional area of superconducting layer. At high voltage where the shunting current is high, the normalized transport current becomes higher than the modified ratio of non-cracked area. The increase in shunting current with transport current (and voltage) leads to a decrease in
n-value at high current (voltage). This phenomenon is enhanced by crack extension.
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