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The use of transmission lines is widely accepted in the design of multiple active and passive devices given their capabilities to operate with signals in the whole frequency spectrum. However, a factor that difficult their design is the coupling effect when there are multiple transmission lines in parallel. Depending of the application, this factor could have a beneficial or detrimental effect in transmission lines. In particular, superconducting parametric amplifiers experiment this effect. The focus of this paper to understand the crosstalk so future superconducting parametric amplifiers can be designed considering the crosstalk. The study was achieved using coplanar waveguide transmission lines, artificial coplanar waveguide transmission lines, and microstrip lines. Dimensions of state-of-the-art (SOTA) parametric amplifiers have been used to have a suitable comparison with the nowadays state of the art superconducting parametric amplifiers. [ABSTRACT FROM AUTHOR]

NbTe2 is a distorted monoclinic quasi-two-dimensional layered semimetal with superconductivity at 0.5 K. We report the investigation of the influence of Cu substitution on the superconductivity in NbTe2. Surprisingly, we found that a very small amount of Cu doing in Nb sites can greatly enhance the superconductivity of Nb1−xCuxTe2 single crystal samples. The superconducting transition temperature increases 6 times to 3 K for the optimal composition Nb0.95Cu0.05Te2, and then decreases for higher x; the superconducting transition temperature disappears when x = 0.1, which forms a dome-shaped superconducting phase diagram. [ABSTRACT FROM AUTHOR]

In this study, zinc (Zn)-doped YBaCuO (YBCO)-123-based high-temperature superconducting samples were produced using the sol-gel method, which is commonly used for preparing nanosize materials. Zn ions were substituted by Cu ions (YBa2Cu3-xZnxO), and Zn doping effects on structural, electrical, and mechanical properties of the YBCO-123 superconductors were examined in detail. Undoped sample was prepared under same conditions. X-ray diffraction analysis (XRD) was used to determine phase analysis and lattice parameters of the superconducting samples. To analyze the microstructure properties, scanning electron microscope (SEM) measurements were performed. Resistivity and microhardness measurements were also carried out for superconducting and mechanic properties, respectively. Vickers microhardness, young modulus, fracture toughness, and yield strength values of the samples were calculated. Microhardness measurements were analyzed using the Kick's law, proportional sample resistance (PSR) model, EPD model, the Hays-Kendall (HK) approach, and indentation-induced cracking (IIC) model. [ABSTRACT FROM AUTHOR]

In this paper, the results of the superconductivity evaluation of MgB2 intermetallic-based superconducting materials prepared through mechanical alloying are reported. The formation of the MgB2 intermetallic phase took place through an intermediate phase reaction at the solid-state reaction temperature, which tends to favor single-phase materials. The annealing of mechanically milled Mg and B powders resulted in the highest mass fraction of MgB2 observed in this study, reaching more than 90% after annealing at 900 °C for 1 h. At that point, there were still second phases present consisting of Mg, MgO, and Fe2B. Improved superconducting properties were obtained in samples sintered at temperatures of 850 °C and 900 °C that had a low resistivity, low critical temperature gap values, and a high residual resistivity ratio (RRR). [ABSTRACT FROM AUTHOR]

In this paper, the results of the superconductivity evaluation of MgB2 intermetallic-based superconducting materials prepared through mechanical alloying are reported. The formation of the MgB2 intermetallic phase took place through an intermediate phase reaction at the solid-state reaction temperature, which tends to favor single-phase materials. The annealing of mechanically milled Mg and B powders resulted in the highest mass fraction of MgB2 observed in this study, reaching more than 90% after annealing at 900 °C for 1 h. At that point, there were still second phases present consisting of Mg, MgO, and Fe2B. Improved superconducting properties were obtained in samples sintered at temperatures of 850 °C and 900 °C that had a low resistivity, low critical temperature gap values, and a high residual resistivity ratio (RRR). [ABSTRACT FROM AUTHOR]

Superconducting fault current limiter, SFCL, forms an important category of fault-current-limiting devices which limit the short-circuit current levels in electrical networks. Therefore, modeling its operation and anticipating its characteristic parameters are too important in its design and optimization process. In this paper a novel integrative method has been proposed which predicts, with a good accuracy, the behavior of inductive shield-type SFCL in different circumstances and approximates its main operational characteristics, as the through current, the inductance and the voltage-current characteristics. An algorithm is presented to calculate the exact distribution of magnetic flux and supercurrent density inside the superconductor bulk in different operational conditions using the well-known Bean model and for the first time the flux pinning effect has been taken into account in SFCL operation modeling. For estimation of flux density distribution outside the superconductor bulk, the FEM analysis has been utilized. An iterative method has been used, based on the numerical solution of differential equations, to calculate the instant value of the SFCL through-current and inductance. The proposed method of modeling has been studied on a specific design of shield-type SFCL and its through current in normal and fault conditions of a test circuit, variation of its inductance with time and its voltage-current characteristic are calculated theoretically. A prototype has been fabricated based on the studied SFCL design and has been tested experimentally. The comparison of the experimental and theoretical results shows that this modeling predicts the SFCL operation with a good accuracy. [ABSTRACT FROM AUTHOR]

In order to study how Cd substitution for Tl changes, the superconducting properties of TlCdBaCaCuO compound with x=0, 0.1, 0.2 and 0.3. We have prepared samples with Cd in place of Tl by the solid state reaction method. It has been found that the increase of the Cd concentrations of all samples produced increases the transition temperature from 113 to 123 K and changes the mass density ρ, C/a and volume fraction V. XRD shows that the partial substitution of Tl with Cd is helpful to form the superconducting 1223 phase (TlBaCaCuO). It has been shown that samples mainly contain tetragonal phase 1223 with a few additional mixed 1212 and 1201 phases. [ABSTRACT FROM AUTHOR]

HgCuSbBaCaCuO High temperature superconducting samples were prepared by using a standard solid-state reaction method with different sintering temperatures of 1073, 1093, 1113, 1133 and 1153 K. The electrical resistivity measurements showed that the sintering conditions have major effects on the transition temperature of the superconducting compound. The samples prepared at 1113 and 1153 K have transition temperatures at zero resistivity T=107,112 K and T)=121,128 K respectively. Meanwhile, the sample prepared at 1133 has highest transition temperature T=121 K and T=134 K. However, the samples which were prepared at 1073 and 1093 K showed metallic behavior with respect to temperature, but this could not help us to obtain the values of T because they were less than the point of liquid nitrogen. The effect of sintering times on the transition temperature has been investigated by using the samples prepared at 1133 K. The value of T at the sintering times of 16-24 hours rises from 121 K to 126 K. The XRD data collected from various samples were all polycrystalline. It was found that the increase of sintering temperatures from 1073-1153 K caused an extremely high amount of decomposition of the low-phase (1212) superconductor and produced high-phase (1223) superconductors. The oxygen content ( δ), volume fraction V and the lattice parameters were changing with the increase of the sintering temperature. [ABSTRACT FROM AUTHOR]

In this work, we present a systematic study on the effect of sintering time on the superconducting behavior of the HgPbSbBaCaCuO compound. Bulk polycrystalline samples have been prepared by a solid state reaction method. It has been observed that the as grown HgPbSbBaCaCuO compound corresponds to the 1223 phase. Electrical resistivity, using the four probe technique, was used to find the transition temperature T. The highest T and T were found to be 116 K and 132 K, respectively, for the sample preparation with a sintering time of 24 hours. X-ray diffraction (XRD) analysis showed a tetragonal structure with a decrease of the c-axis lattice constant with an increase of the sintering time. It was found that the increase of the sintering time produces a change in the c/ a and volume fraction V. [ABSTRACT FROM AUTHOR]

range of nano techniques is explored in order to increase the critical current in pulsed laser deposited (PLD) superconducting YBaCuO (YBCO) thin films. The structural measurements are linked with magnetic and transport measurements of the films. The effectiveness of PLD techniques is analyzed from the point of view of the dimensionality of nanostructures formed prior to and during the film growth. It is shown that a combination of two-dimensional substrate decoration with nanoparticles before the film deposition and one-dimensional growth of external phase nanorods during the deposition offers a high critical current in magnetic field both along the c-axis and in the ab-plane of YBCO. [ABSTRACT FROM AUTHOR]

The synthesis of MgB-based materials under high pressure gave the possibility to suppress the evaporation of magnesium and to obtain near theoretically dense nanograined structures with high superconducting, thermal conducting, and mechanical characteristics: critical current densities of 1.8-1.0×10 A/cm in the self-field and 10 A/cm in a magnetic field of 8 T at 20 K, 5-3×10 A/cm in self-field at 30 K, the corresponding critical fields being H=15 T at 22 K and irreversible fields H=13 T at 20 K, and H=3.5 T at 30 K, thermal conduction of 53±2 W/(m⋅K), the Vickers hardness H=10.12±0.2 GPa under a load of 148.8 N and the fracture toughness K=7.6±2.0 MPa⋅m under the same load, the Young modulus E=213 GPa. Estimation of quenching current and AC losses allowed the conclusion that high-pressure-prepared materials are promising for application in transformer-type fault current limiters working at 20-30 K. [ABSTRACT FROM AUTHOR]

Many superconducting delay line structures have been implemented, using various technologies. In this paper, a comprehensive overview of these delay-lines is given. The advantages and disadvantages of using different planar technologies for the construction of superconducting delay lines are discussed in greater detail. It was revealed that most of the superconducting delay line structures reported can be categorized into a few popular structures, namely meander line, double-spiral line, and unit-cell structures. Our recently published novel double-spiral meander delay line structure is also included for comparison. The new structure was implemented using both microstrip and coplanar technologies and the performance is superior compared to any delay lines reported previously. Besides, investigated meander and fractal delay line structures were also reported, with theoretical analysis in frequency and time domains. [ABSTRACT FROM AUTHOR]

Nanoengineered periodic array of holes on superconducting thin films have a great interest due to their excellence for the studies of the vortex pinning mechanisms in the type-II superconductors. Rectangular array of holes has been fabricated over a microbridge of Nb superconducting thin film by e-beam lithography. Rectangular array of holes have two type of scenario, at low magnetic fields matching effects are sharp and narrow while at high fields wide and shallower. In this work, we study the matching pinning effect by the artificial hole array in superconducting Nb thin films. We observed that as the inter distance between holes is decreased; the sharp matching effects become dominant and vice versa. [ABSTRACT FROM AUTHOR]

Patterned superconducting thin films having a periodic array of submicrometric pinning centers have been of great interest due to their excellence for the studies of the vortex pinning mechanisms in the type-II superconductors. Square hole array has been fabricated over a micro-bridge 60 mm×60 mm of NbN thin film by electron beam lithography. Previous works have been carried out in Nb, Pb and Al thin films where the vortex pinning effect is assumed to be small. In this work, we study the matching pinning effect by the artificial hole array in superconducting NbN thin films. We observed the interplay between the vortex quantization and the artificial hole array. Magneto-resistance minima at integer matching fields up to five times of H (the first matching field corresponding to one vortex inside each hole) and fractional matching fields at 1/2 H, 3/2 H and 5/2 H have been observed. [ABSTRACT FROM AUTHOR]

BEPCII cryogenic system consists of a cavity cooling loop and a magnet cooling loop. Although the magnet cooling loop has lower heat load than the cavity cooling loop, it needs much more helium mass flow since only sensible heat of the supercritical helium is used to cool the SCQ magnets. As a result, excess liquid helium exists in the return line of the magnet cooling loop and should be evaporated by electrical heater, leading to a waste of cooling power. This paper discusses several solutions for operating the system economically. [ABSTRACT FROM AUTHOR]