Study of the superconducting properties of Niobium in linear Accelerators

该项目的重点是研究铌的超导特性（临界场、亚稳态、损耗等），这些特性将用于在线性加速器中构建超导谐振腔。TESLA （Tera电子伏特超导直线加速器）是一个e+ - e-直线对撞机项目，初始总能量为500 GeV，可扩展到800 GeV。特斯拉计划整合一个x射线激光实验室，该实验室将允许探测物质的快速动态过程，如生物和化学反应以及物质相变。铌是超导加速结构的首选材料。在过去10年里获得的空腔性能的改进使特斯拉在成本上与其他项目相比具有竞争力，所有项目都使用普通导体。超导技术的主要优点是产生高质量的光束，这对对撞机和XFEL都是非常重要的。特斯拉需要具有极致性能的空腔。研究铌的超导特性是推动空腔向更高性能发展的关键。因此，我们希望在这项工作中：表征以不同方式加工的空腔材料的铌，研究线性表面电阻和潜在的损失机制，并探索它们与动态驱动涡旋物质的关系。

The project is focused on the study of the superconducting properties (critical fields, metastability, losses, etc...) of niobium that will be used to build superconducting resonant cavities in linear accelerators. TESLA (Tera Electronvolt Superconducting Linear Accelerator) is a project for a e+ - e- linear collider of initially 500 GeV total energy, extendable to 800 GeV. TESLA is planned to integrate an X-ray laser laboratory, which will allow to probe fast dynamic processes of matter such as biological and chemical reactions and matter phase transitions. Niobium is the choice of the superconducting accelerating structures. The improvement on the cavities performances obtained in the last 10 years made TESLA competitive in cost with the other projects, all using normal conductors. The main advantage of the superconducting technology is the production of high quality beams, which are of eminent importance for both the collider and the XFEL. TESLA needs cavities of ultimate performance. The study of the superconducting properties of niobium is crucial to push the cavities to higher performances. For this reason we want in this work to: characterise the niobium of the cavities materials processed in different ways, study the linear surface resistance and the underlying losses mechanisms and explore their relation to dynamically driven vortex matter.