Fundamental Research in SRF at TRIUMF

优化和理解射频性能的研究主要集中在椭圆1.3GHz电子加速腔上。一种新的强子SRF直线加速器正在开发中，它将以连续波（cw）射频功率工作。强子加速器的腔体是利用瞬变电磁法加速模式的非椭圆结构，必须在5%到80%的光速范围内加速粒子速度，通常在100MHz到700MHz的射频频率范围内。我们的工作使我们确信，要了解新工艺和新材料的性能，需要研究材料的微观行为以及完整谐振器结构的性能。该提案的PI使用了先前的发现拨款和RTI资金来支持学生和设备安装射频感应炉，为多个频率的射频低温测试提供两个同轴腔，并探索Nb和新材料的性能（T. Junginger等）。Prab 2018 21,03 2002)。此外，RTI资金已用于购买新的betaNMR光束线设备，以进一步研究SRF材料。所有的设备都是为了支持学生为基础的研究项目。这里所要求的资金将使我们能够继续利用TRIUMF和不列颠哥伦比亚大学的专业知识和设备，以及内部和外部合作者提供的材料，在微观层面上探索材料。特别是，我们将继续进行muSR测量以进行批量测试，并完成ß-NMR设施的新光谱仪，以允许在表面进行测试场抑制。该设备将允许测量样品中接近迈斯纳态极限的磁场穿透，作为穿过伦敦层深度的函数。β - nmr深度剖面诊断将提供世界上独一无二的测试基础设施，为层状结构的有效性提供重要答案，并为SRF研究开辟新的机会。我们的全谐振器研究计划将主要集中在优化非椭圆同轴腔（TEM）的性能上。所述腔的尺寸允许在射频感应炉中进行包括掺杂在内的批量热处理。在研究过程中，我们提出在共轴谐振器上安装H-map系统和T-map系统，在低温恒温器上安装多轴亥姆霍兹线圈，以研究共轴几何形状下的磁通排出。射频感应炉也允许在样品上发展Nb3Sn涂层，然后是单细胞椭圆和TEM模式腔。后者可以测试Nb3Sn作为射频频率和射频场的函数的有效性。这些资金被要求用于发现科学。在探索过程中，学生和年轻的专业人士将在追求突破性问题的同时接受培训。

Studies to optimize and understand rf performance have been focused on elliptical 1.3GHz cavities for electron acceleration. A new wave of hadron SRF linear accelerators are being developed that would operate with continuous wave (cw) rf power. The cavities for hadron accelerators are non-elliptical structures utilizing the TEM accelerating mode and must accelerate a wide range of particle velocities from 5% to ~80% the speed of light and with rf frequencies ranging from 100MHz to 700MHz typically. Our work has convinced us that an understanding of the performance of new processes and new materials requires the ability to study both the microscopic behaviour of materials as well as the performance of full resonator structures. The PI on this proposal has used a previous Discovery grant and RTI funds to support students and equipment to install an rf induction oven, to source two coaxial cavities for rf cryogenic testing at multiple frequencies and to explore the performance of Nb and new materials with muSR (T. Junginger et al. PRAB 2018 21, 032002). In addition RTI funds have been used  to purchase equipment for a new betaNMR beamline to further study SRF materials. All the equipment is geared to support student based research programs. The funds requested here will allow us to continue to explore materials at the microscopic level utilizing the expertise and equipment at TRIUMF and the University of British Columbia and materials sourced both internally and through external collaborators. In particular we will continue muSR measurements for testing in the bulk and complete the new spectrometer to the ß-NMR facility to allow testing field suppression at the surface. The facility would allow measurements of the magnetic field penetration in the sample near the limits of the Meissner state as a function of depth through the London layer. The beta-NMR depth profile diagnostic would offer a test infrastructure unique in the world for providing important answers to the effectiveness of layered structures and open new opportunities in SRF research. Our program of full resonators study will focus mainly on optimizing the performance of non-elliptical coaxial cavities (TEM).  The cavities are sized to allow bulk heat treatments including doping in the rf induction oven. During the course of this study we propose to outfit the coaxial resonators with an H-map system and T-map system and the cryostat with multi-axis Helmholtz coils to study flux expulsion in the coaxial geometry. The rf induction oven would also allow development of Nb3Sn coatings on samples then single cell elliptical and TEM mode cavities. The latter would enable testing the effectiveness of Nb3Sn as a function of rf frequency and rf field. The funds are requested to enable discovery science. During the quest students and young professionals will be trained while pursuing ground breaking questions.