Current Enhancement by Fission-Induced Columnar Defects in High Temperature Superconductors

9510731 Thompson本项目将研究裂变诱导的柱状缺陷对各种高TC材料中涡旋钉扎的影响，这些材料包括实际的掺铅Bi2223/Ag复合线或带，汞基铜酸盐外延薄膜和块材，以及Bi2212单晶。我们的目标是开发实用的方法来提高这些材料的临界电流密度Jc，方法是故意在GeV范围内的光粒子照射下引入扩展的缺陷，并有可能扩大到大型预制结构。该项目结合了田纳西大学诺克斯维尔分校和IBM T·J·沃森研究中心的小组的共同努力，他们在超导体研究以及各种磁性和运输方法方面都表现出了专业知识。该项目还利用了洛斯阿拉莫斯国家实验室的专业知识和辐射设施，以及美国超导公司的电线和磁带制造技术。由于制造能够承载大电流的线或带的困难，即具有在强磁场中可持续的大临界电流密度Jc，高温超导体的大规模应用尚不可能。这些问题与高T_c材料在磁场作用下所固有的电流“涡旋”的耗散运动有关。该项目使用辐射诱导的损伤中心，或柱状缺陷，其作用是固定住涡旋，使其无法移动，从而极大地增强材料的载流性能。该项目结合了田纳西大学诺克斯维尔分校和IBM T·J·沃森研究中心的小组的共同努力，他们在超导体研究以及各种磁性和运输方法方面都表现出了专业知识。该项目还利用了洛斯阿拉莫斯国家实验室的专业技术和辐射设施，以及美国超导公司的电线和磁带制造技术。***

9510731 Thompson This project will investigate the effect of fission-induced columnar defects on vortex pinning in a variety of high-Tc materials, such as practical Pb-doped Bi-2223/Ag composite wire or tapes, Hg-based cuprate epitaxial films and bulk materials, and Bi-2212 single crystals. The goal is to develop practical ways to enhance the critical current density, Jc, in these materials via deliberate introduction of extended defects with GeV range light particle irradiation, with potential for scale-up to large prefabricated structures. The project incorporates a focused joint effort of groups at the University of Tennessee, Knoxville, and at IBM T. J. Watson Research Center, with demonstrated expertise in studies of superconductors and in various magnetic and transport methods. The project also draws on the expertise and irradiation facilities at Los Alamos National Laboratory and on fabrication of wires and tapes at the American Superconductor Corporation. %%% Large-scale applications of high temperature superconductors are not yet possible due to difficulties in manufacturing wires or tapes capable of carrying large currents, that is, having large critical current densities, Jc, sustainable in high magnetic fields. The problems are related to dissipative motion of current "vortices" which are intrinsic to the high-Tc materials in the presence of magnetic fields. This project employs radiation induced damage centers, or columnar defects, which act to "pin" the vortices so they are unable to move, and, as a result, greatly enhance the current carrying properties of the materials. The project incorporates a focused joint effort of groups at the University of Tennessee, Knoxville, and at IBM T. J. Watson Research Center, with demonstrated expertise in studies of superconductors and in various magnetic and transport methods. The project also draws on t he expertise and irradiation facilities at Los Alamos National Laboratory and on fabrication of wires and tapes at the American Superconductor Corporation. ***