Epitaxial Growth of CeO<Subscript>2</Subscript>/YSZ/CeO<Subscript>2</Subscript> Buffer Layers on Textured Ni Substrates for YBCO Conductors

CeO₂/YSZ/CeO₂ buffer layers were deposited on textured Ni substrates byin situ pulsed laser deposition. The out-of-plane texture and in-plane texture of the buffer layers were characterized by X-ray diffraction ω-scans and ϕ-scans. Using this CeO₂/YSZ/CeO₂ architecture as the buffer layers, high quality YBCO films with a zero-resistanceT _c about 90 K and a self-field critical current densitiesJ _c above 10⁶ A/cm² at 77 K can be obtained on Ni substrates.     

MgB2超导体线带材的成材研究

介绍了MgB2超导线带材的制备及影响线带材临界电流密度的因素.MgB2超导线带材的主要制备方法是先位粉末套管法和原位粉末套管法.MgB2超导线带材的临界电流密度受多种因素影响,包括外包套金属材料、初始粉末粒度、掺杂元素、形变和热处理等.通过研究这些因素,能有效改善MgB2的临界电流密度.     

Design and performance of compensator for decremental persistent current in HTS magnets using linear type magnetic flux pump

This paper has described the characteristics of a stationary linear type magnetic flux pump newly developed this time. The linear type flux pump aims to compensate a little decremental persistent current of the HTS magnet in NMR and MRI systems. The flux pump mainly consists of DC bias coil, 3-phase AC coil and Nb foil. Analytical results by the FEM are proved to nearly agree with experimental ones. In the experiment, it has been investigated that the flux pump can effectively charge the current in the load coil of 1.3 mH for various frequencies in 150 s under two following conditions: (1) DC bias of 10 A and AC of 4 A_rms, (2) DC bias of 10 A and AC of 5 A_rms. The maximum magnitudes of initial increasing rate of pumping current and load magnet voltage are: (1) 0.2 A/s and 25 mV and (2) 0.22 A/s and 34 mV, respectively.     

Fabrication of NiO Buffer Layer for YBCO Coated Conductors by Combining Sputtering and SOE Method

In research of YBCO coated conductors, the development of a oxide template for epitaxial growth of YBCO is very important. Matsumoto et al have demonstrated the potential of the surface oxidation epitaxial (SOE) route for formation a cube textured NiO layer on nickel tapes. The epitaxial NiO functions as a buffer layer of chemical reaction between YBCO and nickel, and as a template for the epitaxial growth of YBCO. However, the surface quality of NiO is difficult to control and defects such as crack, spall and deep grooves exist in SOE NiO layer. A new approach combining sputtering and SOE method to obtain crack-free and cube textured NiO layer were reported. Ni tapes prepared by the combination of rolling and recrystallization were used for this work. A coating of Ni was first deposited on the tapes via magnetron sputtering. Then on the coating tapes, continuous and textured NiO layer were achieved by SOE technology.     

HTS filter and front-end subsystem for GSM1800 wireless base station

The first HTS front-end subsystem for wireless base station in China was developed. This demonstration system, which aims at the application in GSM 1800 mobile communication base station, consists of a single RF path, i.e. one filter and one LNA, integrated with the pulse tube cooler. The subsystem works at a pass band of 1710-1785 MHz with a gain of 18 dB and at a temperature of 70 K. The accomplishment of such a demonstration subsystem can boost the development of HTS commercial subsystem.     

超导体的电磁波解

在广义协变的伦敦方程基础上讨论了超导体的电动力学特性,并由此建立起超导体的电磁波动方程.通过对该方程的进一步分析后我们发现,在超导体中不仅存在电磁波动解,而且还存在类似于常规导体的电磁波趋肤效应,其趋肤尺度明显地依赖于电磁波的波动频率.具体地说就是,当电磁波频率ω～√α/E0时,超导体将表现出与常规导体相似的趋肤特性;在高频情况下,两者的这种趋肤性质则会表现出比较显著的差别.     

基于IGBT开关的超导电感脉冲输出实验研究

为实现高温超导电感脉冲功率输出,在对多种断路开关特性比较的基础上,提出了基于IGBT开关的超导电感模块化脉冲输出方案。在该方案的基础上建成了一套基于IGBT开关的脉冲输出回路,利用实验室的高温超导磁体进行了一系列的试验,最终在负载上得到峰值约为40 A,上升沿约为200μs的单电感放电脉冲波形和多电感放电叠加的脉冲波形。试验结果表明,用IGBT作为断路开关控制磁体能量以实现脉冲功率输出的技术方案是可行的。     

EBSD analysis of melt-textured YBCO with embedded Ag-2411 nanoparticles

Nanoparticles of the type M-2411 (with M = U, Nb, Zr, Ag, etc.) can be embedded within the superconducting YBCO matrix to provide flux pinning sites. Among all these types of nanoparticles, the Ag-2411 particles are special in the sense that they may provide also metallic Ag particles to be formed within the superconductor. The addition of metallic Ag (or silver oxide) was shown to be a means to create a more stable system by filling cracks and voids. Using the advanced polishing method of the YBCO surfaces, we achieve a high EBSD image quality of the recorded Kikuchi patterns. In this contribution, we perform a four-phase EBSD analysis including YBa₂Cu₃O_x, Y₂BaCuO₅, Ag-2411 and metallic Ag. As a result, we find nanometer-sized Ag particles being distributed within the YBCO matrix, and a reduced amount of Ag-2411 particles as compared to the nominal composition. The Ag-2411 particles are well oriented with the surrounding YBCO matrix as found earlier, but the metallic silver particles as detected by EBSD do not exhibit a preferred orientation.     

Structural analysis of high-Tccuprate superconductors

We have shown in this paper that members of the Tl-Ba-Ca-Cu-O and Bi-Sr-Ca-Cu-O superconducting families fabricated so far are built up of superconductor-semiconductor arrays. Four general homologous series are written down for these two families. The basic fundamental block in each series is itself a superconductor. We suggest that the Y-Ba-Cu-O family has a similar characteristic if YBaCu₂O_5-d is a superconductor.     

基于改进桥路型的高温超导限流器的研制及现场试验研究

笔者提出了改进型桥路模型,该模型可限制瞬态短路电流和稳态短路电流。文中对电阻型、桥式和改进桥式超导限流器进行了仿真,提出了高温超导限流器的技术方案和技术参数,在此基础上研制了10 kV高压系统的高温超导限流器。限流器于2005年8月14日在湖南省娄底电业局高溪110 kV变电站进行了短路试验,并挂网运行。短路试验中,成功将3 500 A(有效值)限制到635 A(有效值),且短路瞬间波形无突变。从6个月的运行经验来看,超导限流器各种运行指标良好,为超导限流器的规模应用奠定了基础。