论文标题
几何形状对超导加速腔的磁通量捕获的影响
Impact of geometry on the magnetic flux trapping of superconducting accelerating cavities
论文作者
论文摘要
在现代加速器项目中，在超导射频（RF）腔中控制捕获的磁通量至关重要。为了研究磁通捕获效率和表面电阻的敏感性，已经对不同类型的低\ \ b {eta}超导加速腔进行了专用实验。即使在几乎完全的捕获条件下，我们发现这些空腔几何形状的测得的磁敏感性显着低于基于局部材料特性的常用模型预测的理论值。必须考虑到在这种空腔形状下的RF表面电流下通量捕获和通量振荡的几何影响来解决这一问题。在本文中，我们提出了一种新的方法来消除几何形状的影响。我们指出，样品测量结果与最近的空腔实验之间存在令人困惑的矛盾，这导致了两个不同的假设，以模拟被捕获在空腔表面中的振荡通量。与椭圆形腔中的温度映射研究相比，RF Lorentz力对通量振荡的临界重新考虑，有利于先前的样品测量结果，这表明正常成分的优先通量陷入了腔体内表面。基于此观察，我们为实验结果建立了一个新的模型，并解决了旧理论和数据之间的差异。
Controlling trapped magnetic flux in superconducting radiofrequency (RF) cavities is of crucial importance in modern accelerator projects. In order to study flux trapping efficiency and sensitiv- ity of surface resistance, dedicated experiments have been carried out on different types of low-\b{eta} superconducting accelerating cavities. Even under almost full trapping conditions, we found that the measured magnetic sensitivities of these cavity geometries were significantly lower than the theoretical values predicted by commonly-used models based on local material properties. This must be resolved by taking account of geometrical effects of flux trapping and flux oscillation under RF surface current in such cavity shape. In this paper, we propose a new approach to convolute the influence of geometries. We point out a puzzling contradiction between sample measurements and recent cavity experiments, which leads to two different hypotheses to simulate oscillating flux trapped in the cavity surface. A critical reconsideration of flux oscillation by the RF Lorentz force, compared with temperature mapping studies in elliptical cavities, favoured the results of previous sample measurements, which suggested preferential flux trapping of normal component to the cavity inner surface. Based on this observation, we builded a new model to our experimental results and the discrepancy between old theory and data were resolved.
