Processing and testing equipment for Coaxial Test Resonators

同轴测试谐振器加工和测试设备

• 批准号: SAPEQ-2021-00006
• 负责人: Laxdal, Robert
• 金额: $ 3.64万
• 依托单位: TRIUMF
• 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=743099
• 关键词: Processing; testing; equipment; Coaxial; Test

Studies to optimize and understand superconducting radio-frequency (SRF) performance have been primarily focused on elliptical 1.3GHz cavities for electron acceleration. A new wave of hadron SRF linear accelerators are being developed that will operate with continuous wave (cw) rf power. The cavities for hadron accelerators utilize the transverse electric and magnetic (TEM) accelerating mode and must accelerate a wide range of particle velocities from 5% to ~60% the speed of light and with rf frequencies ranging from 100MHz to 700MHz typically.  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 [5] at multiple frequencies and to explore the performance of Nb and new materials with muSR and beta-NMR [1,2,3,4,6]. All the equipment is geared to support student based research programs and leverages TRIUMF SRF and material science infrastructure. The funds requested here will allow us to augment the coaxial resonator program by expanding our processing and testing equipment. Present TEM mode bulk Niobium cavities almost exclusively use Buffered Chemical Polish (BCP) as a step to remove ~150microns of damaged layer after fabrication or to reset the rf surface of the cavity between processing steps. The elliptical cavity community primarily uses Electropolish (EP) surface removal  since comparative studies show that the high field performance is improved over the BCP technique. Also, certain new heat treatments like N2 doping [8] applied to improve the performance of elliptical cavities need a post-treatment EP to optimize the treatment.  Due to the complex geometry of TEM mode cavities, EP has been done in only a few Labs [7] and no studies have been done to compare the performance of EP vs BCP on the same TEM cavity. Further, no TEM mode cavity has been treated with N2 doping. We propose to purchase equipment through this RTI to enable EP on the two coaxial cavities [15] to allow us to, for the first time, compare EP vs BCP on the same TEM cavity. Further we plan to use the EP process to allow N2 doping of the TEM mode cavities also for the first time. To augment the study we propose to purchase equipment and parts for a TEM mode temperature mapping (T-map) system to enable us to discern between localized or global losses in the cavities. Such information is crucial to better define rf surface resistance vs rf frequency. We also request funds to procure parts to add accurate low field magnetic probes to allow also H-mapping of the cavity during cooldown. The magnetic probes in combination with T-map will give us detailed information on geometry dependent flux trapping. The RTI funds requested in this proposal will provide a unique set of tools to enable student led discovery science and provide breakthroughs in the rapidly evolving SRF technology sector.

优化和理解超导射频(SRF)性能的研究主要集中在用于电子加速的椭圆形1.3 GHz腔体上。新一波强子SRF直线加速器正在研制中，它将以连续波(CW)射频功率工作。强子加速器的腔体采用横向电磁加速模式，需要加速的粒子速度从光速的5%到60%不等，射频频率一般在100 MHz到700 MHz之间。关于这项提案的PI使用了之前的Discovery补助金和RTI资金来支持学生和设备安装射频感应炉，为多频率的RF低温测试[5]寻找两个同轴腔体，并利用muSR和beta-核磁共振来探索NB和新材料的性能[1，2，3，4，6]。所有设备都旨在支持以学生为基础的研究项目，并利用TRIUMF SRF和材料科学基础设施。这里要求的资金将使我们能够通过扩大我们的加工和测试设备来扩大同轴谐振器计划。目前的TEM型块状Nb腔几乎完全使用缓冲化学抛光(BCP)作为加工后去除~150微米损伤层的步骤，或者在工艺步骤之间重新设置腔的射频表面。椭圆形空腔社区主要使用电抛光(EP)表面去除，因为比较研究表明，高场性能比BCP技术有所改善。此外，某些新的热处理，如氮气掺杂[8]，用于改善椭圆腔的性能，需要一个处理后的EP来优化处理。由于TEM模腔的复杂几何形状，EP只在几个实验室[7]中进行，还没有研究比较EP和BCP在相同的TEM腔上的性能。此外，还没有用氮气掺杂处理过的TEM模腔。我们建议通过这种RTI购买设备，以便在两个同轴腔上实现EP[15]，从而使我们能够第一次在同一个TEM腔上比较EP和BCP。此外，我们还计划首次使用EP工艺来允许在TEM模腔中掺杂氮气。为了加强这项研究，我们建议购买用于瞬变模式温度映射(T-MAP)系统的设备和部件，以使我们能够识别腔体中的局部或全局损耗。这些信息对于更好地确定射频表面电阻与射频频率之间的关系至关重要。我们还要求获得资金来采购部件，以添加准确的低场磁探头，以便在冷却期间也能对空腔进行H映射。磁性探头与T-MAP相结合，将为我们提供与几何有关的磁通捕获的详细信息。这项提案中要求的RTI资金将提供一套独特的工具，使学生主导的发现科学成为可能，并在快速发展的SRF技术部门取得突破。