The design of suitable electromagnetic bandgap (EBG) cavities has been performed by means of a hybrid numerical/analytical approach implemented via a homemade code with the aim of optimizing a novel accelerating structure for proton linear accelerators (linacs). In particular, a 3-GHz proton linac tank with on-axis coupled EBG cavities closed with full-end cells has been optimized. The proton beam input energy is 27 MeV. The performances of the proton linac EBG accelerating cavities have been compared with the performances of 27-MeV 3-GHz side-coupled proton linac accelerating cavities in terms of typical linac figures of merit. The use of EBG cavities allows to increase the transit time factor (by about 8%). Moreover, the peak surface electric field is strongly reduced (by about 65%), paving the way to the design of very high accelerating gradient microwave proton linacs. Furthermore, the wakefields of the EBG structure have been compared with those of the SCL structure, showing that the EBG structure provides effective damping of the transverse wakefields.

中文翻译：

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高梯度同轴耦合腔直线加速器电磁带隙腔设计


合适的电磁带隙（EBG）腔的设计是通过自制代码实现的混合数值/分析方法进行的，目的是优化质子直线加速器（直线加速器）的新型加速结构。特别是，具有用全端单元封闭的同轴耦合 EBG 腔的 3 GHz 质子直线加速器槽已经过优化。质子束输入能量为27 MeV。质子直线加速器 EBG 加速腔的性能与 27 MeV 3 GHz 侧耦合质子直线加速器加速腔的性能在典型直线加速器品质因数方面进行了比较。使用 EBG 腔可以增加传输时间系数（约 8%）。此外，峰值表面电场大幅降低（约65%），为极高加速梯度微波质子直线加速器的设计铺平了道路。此外，将EBG结构的尾流场与SCL结构的尾流场进行了比较，表明EBG结构对横向尾流场提供了有效的阻尼。