Low cost vibrating sample magnetometer to study materials for superconducting radiofrequency cavities

用于研究超导射​​频腔材料的低成本振动样品磁力计

• 批准号: SAPEQ-2021-00008
• 负责人: Junginger, Tobias
• 金额: $ 10.86万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Research Tools and Instruments
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743065
• 关键词: Low; cost; vibrating; sample; magnetometer

The International Linear Collider (ILC) requires about 17000 superconducting radiofrequency cavities made of the superconducting material niobium. Nowadays niobium cavities perform close to their fundamental limit in terms of achievable accelerating gradient and quality factor. The latter is a measure of the cryogenic efficiency while the accelerating gradient is the energy gain per unit length and ultimately sets the limit to the length of a linear accelerator for a required energy output. Currently, largest accelerating gradients are achieved with normal conducting technology but at the cost of low duty cycle and efficiency. Therefore, for an energy upgrade of ILC normal and superconducting options are currently being considered. Superconducting cavities need to be operated in a flux free Meissner state to avoid dissipation from magnetic vortices. As the accelerating gradient is directly proportional to the surface magnetic field the field of first vortex penetration sets the limitation for the accelerating gradient. Several routes have been proposed using thin film novel superconductors, alternating nanometer thin layers of superconductors and insulators or Nb heat treated under vacuum or in low pressure gas atmosphere. In all cases, the goal is to sustain the Meissner state (vortex free superconducting state) at a higher field compared to bulk Nb technology. Several studies have suggested that the interface between the layered structure provides an additional energy barrier for flux penetration [T. Kubo Supercond. Sci. Technol. vol. 30, p. 023001 (2017)] as well as recovering the stability of the order parameter near defects via the proximity effect [T. Junginger et al. Supercond. Sci. Technol., vol. 30, p. 125012 (2017)]. Elucidating the mechanism and effectiveness of layered superconductors will require probing the local magnetic phase at each layer near the interface and the field of first flux penetration on identical samples. Sample studies with DC methods can allow a quicker and more accurate measurement of the fundamental limiting field without being affected by RF surface conditions and without building entire cavities. To study the magnetic phase at each layer NSERC has funded the beta-SRF facility through a project discovery grant. Here funding is requested to develop a vibrating sample magnetometer to measure the field of first vortex penetration on the same samples to predict the maximum achievable accelerating gradient. Compared to a commercially available instrument developing the instrument at the university will be significantly cheaper and give great opportunities for students developing and operating this instrument.

国际直线对撞机（ILC）需要大约17000个由超导材料铌制成的超导射频腔。如今，就可实现的加速梯度和品质因子而言，铌腔的性能已接近其基本极限。后者是低温效率的量度，而加速梯度是每单位长度的能量增益，并且最终设定了对于所需能量输出的线性加速器的长度的限制。目前，最大的加速梯度是用正常的导电技术实现的，但代价是低占空比和效率。因此，目前正在考虑对ILC进行能量升级的正常和超导选择。超导腔需要在无磁通迈斯纳状态下工作，以避免磁涡旋的耗散。由于加速梯度与表面磁场成正比，因此第一涡流穿透的场设置了加速梯度的限制。已经提出了几条路线，使用薄膜新型超导体，超导体和绝缘体的交替纳米薄层或在真空或低压气体气氛下热处理的Nb。在所有情况下，目标是维持迈斯纳状态（无涡旋超导状态）在一个更高的领域相比，散装铌技术。几项研究表明，层状结构之间的界面为磁通穿透提供了额外的能垒[T。久保超级空调Sci.第30卷，第023001页（2017年）]以及通过邻近效应恢复缺陷附近序参量的稳定性[T. Junginger等人，Supercond. Sci.技术人员：第30卷，第125012页（2017）]。阐明层状超导体的机制和有效性需要探测界面附近每层的局部磁相和相同样品上的第一磁通穿透场。使用DC方法的样品研究可以更快、更准确地测量基本极限场，而不受RF表面条件的影响，也不需要构建整个空腔。为了研究每一层的磁相，NSERC通过项目发现赠款资助了beta-SRF设施。这里要求提供资金，以开发一种振动样品磁力计，用于测量相同样品上的第一涡流穿透场，以预测可实现的最大加速梯度。与市售仪器相比，在大学开发该仪器将便宜得多，并为学生开发和操作该仪器提供了很好的机会。