Electromagnetic Design and Optimization of Superconducting Spoke021 Cavity for C-ADS

为满足C-ADS 项目建设对超导轮辐腔Spoke021的需求，对Spoke021进行了详细的电磁参数优化。对Spoke021的参数化模型进行参数扫描，针对腔体的关键电磁特征量寻找可能存在的极值，详细分析、解释了优化过程中各个参数发生变化的物理意义。在Spoke021各参数达到最终优化值时，表征腔体性能的两个关键比值分别为：E_p/E_(acc) = 3:14，B_p/E_(acc) = 4:77 mT/(MV/m)。考虑到次级电子倍增(Multipacting，MP)对Spoke021运行中所能达到的性能指标有很重要影响，对腔体的MP进行了建模分析。结果表明，当Spoke021工作在Eacc =10 MV/m情况下，没有发生MP，优化得到的参数可以满足Spoke021工程设计的需要；最后计算了腔体的TTF曲线，表明该腔体具有较宽的速度接受度。<div> The electromagnetic optimizations of a superconducting Spoke021 cavity is studied in detail for C-ADS project, in this paper. The cavity model has been parameterized, in order to find the possible maxima or minima of the key electro-magnetic parameters, the parameter sweep is performed. The cavity model has been parameterized. For finding the key electromagnetic feature, the geometric parameter sweep is performed. The physical interpretation for the variation of these electromagnetic parameters has been elaborated. The electromagnetic simulation gives the optimum parameters E_p/E_(acc) of 3.14 and B_p/E_(acc) of 4.77 mT/(MV/m). In addition, the Multipacting(MP) has a great effect on the electromagnetic properties of superconducting Spoke021 cavity. So the MP simulations have been done for this cavity, which shows that there is no MP phenomenon at 10 MV/m accelerator gradient. Therefore, the optimized cavity parameters can satisfy the requirements of the C-ADS project. Finally, the TTF(Transit Time Factor) curve of this cavity is calculated and it shows that this cavity has wide velocity acceptance.</div> <div> &nbsp;</div>中国科学院战略性先导科技专