scholarly journals Thermal Cycling of (RE)BCO-Based Superconducting Tapes Joined by Lead-Free Solders

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1052
Author(s):  
Michal Skarba ◽  
Marcela Pekarčíková ◽  
Lubomír Frolek ◽  
Eva Cuninková ◽  
Martin Necpal
Keyword(s):  
Critical Current ◽  
Cross Section ◽  
Dominant Role ◽  
Superconducting Tapes ◽  
Thermal Cycles ◽  
Superconducting Tape ◽  
Preparation Conditions ◽  
Current Voltage ◽  
Lead Free Solders

We prepared overlap soldered joints of high-temperature superconducting tapes, using various materials and preparation conditions. In order to select the joints with optimal performance, we correlated their electrical properties (derived from current–voltage curves) with the microstructure of the respective joint cross-section by scanning electron microscopy. With the first group of joints, we focused on the effect of used materials on joint resistivity and critical current, and we found that the dominant role was played by the quality of the internal interfaces of the superconducting tape. Initial joint resistivities ranged in the first group from 41 to 341 nΩ·cm2. The second group of joints underwent a series of thermal cyclings, upon which the initial resistivity range of 35–49 nΩ·cm2 broadened to 25–128 nΩ·cm2. After the total of 135 thermal cycles, three out of four joints showed no signs of significant degradation. Within the limit of 100 thermal cycles, reliable soldered joints can be thus prepared, with normalized resistivity not exceeding 1.4 and with normalized critical current above the value of 0.85.

The Effects of Nucleation and Growth on Epitaxy in the CoSi2/Si System

1981 ◽  
Vol 10 ◽  
Author(s):  
J. M. Gibson ◽  
J. C. Bean ◽  
J. M. Poate ◽  
R. T. Tung
Keyword(s):  
Cross Section ◽  
Defect Structure ◽  
Ultrahigh Vacuum ◽  
Nucleation And Growth ◽  
Silicon Substrates ◽  
Pinning Mechanism ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Silicide Growth

The epitaxial perfection and microstructure in thin CoSi2 (111) (and NiSi2) films on silicon has been examined using transmission electron microscopy, including high resolution cross section techniques. We find that, under ultrahigh vacuum preparation conditions only, genuine single-crystal epitaxy can occur for bothreacted and codeposited CoSi2 films. A unique interfacial defect structure is associated with this epitaxy, in which the silicide films are rotated through 180° about (111) with respect to the silicon substrates. Under less than perfectly clean conditions epitaxial perfection is never obtained for CoSi2. Moreover such perfection has never been attained under any conditions for NiSi2 on Si(111). By studying the evolution of epitaxy and defect structure in thin and thick films we have proposed a model to explain the unique quality of ultrahigh vacuum CoSi2 films. The model invokes a defect pinning mechanism to explain the dominance of the 180°-rotated epitaxy during silicide growth.

Critical current and ac susceptibility in superconducting tapes with elliptical cross-section

2002 ◽  
Vol 372-376 ◽  
pp. 1788-1791 ◽  
Author(s):  
E Pardo ◽  
A Sanchez ◽  
C Navau ◽  
F Gömöry ◽  
I Husek ◽  
...  
Keyword(s):  
Critical Current ◽  
Cross Section ◽  
Ac Susceptibility ◽  
Elliptical Cross Section ◽  
Superconducting Tapes ◽  
Elliptical Cross

scholarly journals Effect of Self-field and Loosening of Stacked Superconducting Tapes on Critical Current of a Single Pancake Coil

2019 ◽  
Vol 9 (1S3) ◽  
pp. 155-158
Keyword(s):  
Critical Current ◽  
Magnetic Energy ◽  
Operating Temperature ◽  
Superconducting Tapes ◽  
Superconducting Tape ◽  
Operating Current ◽  
Increasing Demand ◽  
Magnetic Energy Storage ◽  
Work Effect ◽  
Normal Conductor

Research on superconducting systems is getting pace due to the increasing demand of efficient machines to fulfill the need of the society. Applications like motors, transformers and magnetic energy storage systems involve the pancake coils tightly bounded with the superconducting tapes. Moreover, all such devices are sensitive to the number of turns and operating current. Critical current of the superconducting tape is most important parameter while designing such machines as if operating current exceeds this value it will turn to a normal conductor. Critical current of the tape is further depending upon the operating temperature, external and self-field. In this work, effect of both self-field and degree of tightness or looseness on the critical current of the tape has been studied. The results showed that the critical current of the tape is significantly affected by both self-field and the inter-distance among the adjacent tapes.

Effect of Tensile Stress on Characteristics of High-Temperature Superconducting Tape

2021 ◽  
Vol 871 ◽  
pp. 165-169
Author(s):  
Quan Chen ◽  
Jin Min Cheng ◽  
Bai Liang Liu ◽  
Ying Xu ◽  
Xiao Lei Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Tensile Stress ◽  
Critical Current ◽  
Cryogenic Temperature ◽  
External Action ◽  
Power Cable ◽  
Superconducting Tapes ◽  
Superconducting Tape ◽  
High Temperature Superconducting

With the discovery of high-temperature superconducting (HTS) tape and the improvement of the performance of the second-generation HTS tape, the application of superconductors in power system is gradually unfolding. There have been many demonstration projects at home and abroad. When the HTS tape is applied to the power cable, the mechanical external action of the cable winding, laying and installation operations, and the Ampere force when the current is applied are applied to it. Stress has an important influence on the critical current characteristic of the superconducting tape. In different application scenarios of the tape, different materials and thicknesses reinforcement layers can be chosen. In this paper, for the YBCO superconducting tapes with different reinforcement layers, a set of systems with critical current under tensile stress at cryogenic temperature is used to study the influence of tensile stress on the critical current of superconducting tape at low temperature. We analyze the influence of the structure of the superconducting tape on the characteristics of the tape and studied its degradation characteristics, which have guiding significance for the design and operation of the superconducting cable.

Regulator Circuit Transformer Voltage-Second Product Analysis

2014 ◽  
Vol 529 ◽  
pp. 501-505
Author(s):  
Chi Zhang ◽  
Ming Zhi He
Keyword(s):  
Power Supply ◽  
Power Electronic ◽  
Product Analysis ◽  
Power Regulator ◽  
Current Voltage ◽  
Three Phase ◽  
The Impact ◽  
Power Electronic Technology ◽  
Primary Current

With the continuous development of power electronic technology, the advantages of thyristor power regulator circuit gradually get more and more applications. It improves the quality of power supply, makes the equipment efficiency and power factor higher and so saves a lot of electricity. Through the calculation of the primary current when thyristor turns off in three-phase power regulator circuit with transformer load, the impact of the thyristors turn-off order on the transformer primary current voltage-second product is analysised, and through simulation the exactness is verified.

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