Investigation of the Effect of Strong Currents on Superconducting Properties and Surface Resistance of High Performance Materials for Accelerator Cavities

该项目的主要目的是提高粒子加速器的性能，为物质的基本性质的高能实验开辟新的可能性。目前，粒子加速器依靠超导射频(SRF)谐振器腔来加速和控制高能碰撞实验(如欧洲核子研究中心的大型强子对撞机)或X射线激光(如SLAC的相干光源)中的带电粒子束。增加SRF腔的加速场，降低功率消耗，是发展下一代加速器的关键。这项工作将追求两个目标。首先是对优化Nb(Nb)合金超导腔背后的基本物理和材料科学机制的理解。第二项工作集中在新的加速结构和超导材料上，与Nb相比，这些材料可以显着改善超导腔的性能。这项工作将提出提高SRF加速器腔性能的有效方法，并将通过提供关键技术领域的培训，吸引对物理和未来应用感兴趣的本科生和研究生。本项目的主要目标是调查SRF材料的局部准粒子态密度，并将其与不同的材料处理(如低温焙烧和氮气注入)和表面电阻测量相关联。准粒子态密度是决定SRF腔功率损耗和高场性能的关键参数。新的实验技术(低温扫描隧道显微镜和光谱学)和理论的协同将使该小组能够解决潜在的物理和材料科学机制，这些机制有助于在SRF腔中实现更高的加速梯度和更低的功率损失。

The primary aim of this project is to improve the performance of particle accelerators, opening new possibilities for high-energy experiments on the fundamental nature of matter. Currently, particle accelerators rely on superconducting radio frequency (SRF) resonator cavities to accelerate and control beams of charged particles in high energy collision experiments (such as at the Large Hadron Collider at CERN) or in x-ray lasers (such as at the Coherent Light Source at SLAC). Increasing the accelerating fields and reducing power consumption of SRF cavities is essential for the development of the next generation of accelerators. Two objectives will be pursued in this work. First is the understanding of fundamental physical and materials science mechanisms behind optimization of the state of the art superconducting cavities made with alloys of Niobium (Nb). The second effort is focused on new accelerating structures and superconducting materials which could significantly improve the performance of the superconducting cavities as compared to Nb. This work will suggest efficient ways of improving the performance of SRF accelerator cavities and will engage undergraduate and graduate students in this area of great interest to physics and future applications by providing them with training in key technological areas.The main goal of this project is to investigate the local quasiparticle density of states of SRF materials and to correlate it with different materials treatments (such as low-temperature baking and nitrogen infusion) and surface resistance measurements. The quasiparticle density of states is a key characteristic determining the power loss and the high-field performance of SRF cavities. The synergy of new experimental techniques (low temperature scanning tunneling microscopy and spectroscopy) and theory will allow the group to address the underlying physics and materials science mechanisms which are instrumental for achieving higher accelerating gradients and lower power losses in SRF cavities.