离子辐照提高第二代高温超导带材磁通钉扎的研究

The critical current density of the second-generation (2G) high-temperature superconducting (HTS) tapes decreases sharply with increase of applied magnetic field, which seriously restricts its application in many fields like electric power, magnets etc. Therefore, it is critical to improve the flux pinning of 2G HTS tapes. . On the basis of improving superconducting properties of YBCO films by introducing various nanoparticles and Rare-earth additions, the influence of nano-defects of different sizes, different densities and different directions on the flux pinning of YBCO superconducting tapes precisely manufactured by ion irradiation will be investigated in this project. The dependence of critical current density (Jc) on external magnetic field angle, critical magnetic field intensity and temperature will be systematically analyzed. Combined with the microstructure of YBCO tapes irradiated by ions, the influence rule of its irradiation parameters-microstructure-superconductivity will be revealed, and the flux pinning mechanism of various defects produced by ion irradiation in the YBCO tapes will be understood and a mathematical model will be established. On this basis, the 2G HTS tapes with a critical current higher than 1000A/cm will be prepared by optimizing the heavy ion irradiation parameters.

第二代高温超导带材的超导性能随外加磁场增加而急剧下降，严重制约了其在电力、磁体等领域的应用。因此，提高第二代高温超导带材的磁通钉扎非常关键。. 本项目拟在掺杂纳米非超导相、稀土元素替代等多种方式提高YBa2Cu3O7-x（YBCO）超导性能的基础上，采用离子辐照第二代高温超导带材，研究由离子辐照精确制造的不同尺寸、不同密度和不同方向的纳米缺陷对YBCO超导带材磁通钉扎的影响。通过系统分析临界电流密度（Jc）与外加磁场角度、临界磁场强度和温度的依赖关系，并结合重离子辐照的YBCO超导带材的微观结构，揭示其辐照参数-微观结构-超导性能三者之间的影响规律，理解离子辐照产生的各种缺陷在YBCO带材内部的磁通钉扎机制，建立数学模型。并在此基础上，优化离子辐照参数制备出临界电流高于1000A/cm的第二代高温超导带材。

以YBa2Cu3O7-x (YBCO) 为代表的第二代高温超导带材由于其优异的综合性能(77 K下不可逆场到达7 T、自场下的临界电流密度达到106 A/cm2)，突破了第一代高温超导带材(Bi系带材)只能用于弱磁场的限制，可全面满足高温区(液氮温区)、强磁场的强电领域应用，大大推动超导电力技术实用化进程。然而，第二代高温超导带材的超导性能随外加磁场增加而急剧下降，严重制约了其在电力、磁体等领域的应用。因此，提高第二代高温超导带材的磁通钉扎非常关键。.本项目以直接用于强电应用的YBCO超导带材作为主要研究对象，开展了氢H、氧O和钛Ti等不同离子辐照对YBCO带材性能的影响。深入研究样品在不同磁场强度和温度的临界电流密度，协同不同类型缺陷改善YBCO涂层导体在磁场下的超导性能，最后优化工艺制备出高载流能力的YBCO高温超导带材。.氢质子辐照剂量为11015p/cm2时，YBCO薄膜的临界电流密度在低温高场下显著提高。其中纯YBCO薄膜在（20K，7T）下，临界电流密度增强了约2.8倍，达到了约2.4MA/cm2；氧离子辐照引入的缺陷在低温中场下可以起到强钉扎作用，当氧离子辐照的辐照剂量为 1.21013ions/cm2时，薄膜的临界电流密度在（20K，2.5T）下增强了约2.4倍，达到了约4.2MA/cm2；钛离子辐照引入的缺陷在高温高场下起到的钉扎作用最强，当钛离子的辐照剂量为 41012ions/cm2时，YBCO带材的临界电流密度在（77K，5T）下增强了近10.6倍，达到了约0.02MA/cm2。在自场下液氮温区的YBCO带材临界电流达到1200A/cm。.我们按计划完成了任务，并实现了预期目标。