高梯度常导腔中磁聚焦场致发射引发的热机械射频击穿
Thermomechanical rf breakdown from magnetically focused field emission in high-gradient normal-conducting cavities
- Northern Illinois University（北伊利诺伊大学）
- Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
- Argonne National Laboratory（阿贡国家实验室）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本文通过追踪真实场图中的场致发射电子，验证了局部轰击模型在高梯度常导腔磁聚焦射频击穿中的适用性，并解析评估了热机械响应，为强磁场下高梯度射频运行提供参考。
中文摘要 AI 辅助
用于μ子对撞机电离冷却的常导射频（rf）腔必须在强螺线管磁场中以高加速梯度运行，此时磁聚焦的场致发射电子会增强射频击穿。在本工作中，我们在直线冷却晶格腔的真实场图中追踪了场致发射电子，以检验先前基于简化场图开发的局部轰击模型的适用性。在可比较的约化场假设下，追踪结果与先前结果吻合良好。完整的射频本征模场和非均匀螺线管场改变了理想化的束流结构，产生依赖于射频相位的质心偏移以及由螺线管边缘场引起的加宽的撞击分布。尽管如此，原始模型仍是估算运行梯度限制的有用框架。利用该模型对热响应进行了解析评估，并变化材料属性以评估热传输与热机械损伤阈值的耦合效应。这些结果可为强螺线管场中的腔体测试、μ子电离冷却通道设计以及其他需要在磁场中进行高梯度射频运行的应用提供参考。
英文摘要
Normal-conducting radiofrequency (rf) cavities for muon-collider ionization cooling must operate at high accelerating gradients in strong solenoidal magnetic fields, where rf breakdown can be enhanced by the magnetic focusing of field-emitted electrons. In this work, field-emitted electrons were tracked in the realistic field maps of rectilinear cooling-lattice cavities to test the validity of the previously developed localized-bombardment picture with simplified field maps. Under comparable reduced-field assumptions, the tracking results show good agreement with previous results. The full rf eigenmode fields and nonuniform solenoidal fields modify the idealized beamlet structure, producing rf phase dependent centroid shifts and broadened impact distributions from solenoid fringe fields. Nevertheless, the original model remains a useful framework for estimating limits on operating gradients. The thermal response is evaluated analytically using this model, with material properties varied to assess the coupled effects of heat transport and thermomechanical damage threshold. These results can inform cavity testing in strong solenoidal fields, muon ionization cooling channel designs, and other applications requiring high-gradient rf operation in magnetic fields.
