BEPCⅡ直线加速结构的整管RF特性计算

RF Characteristic Study on Whole Accelerating Structure for BEPC Ⅱ Linac

为了在加工前对行波盘荷波导加速管的整管RF特性有所了解,在ANSYS软件中利用重新设计的轴对称型耦合器来替换实际的三维耦合器建模,充分利用加速结构的轴对称特性,并在使用较少计算资源和时间的情况下,仅利用1台计算机即可完成对整根加速管全部特性的计算,从而得到其整管RF特性。以BEPCⅡ直线加速器所采用的3m长加速结构为例,使用本方法进行计算得到的填充时间、衰减常数及带宽分别为856ns、0.56Np及3.55 MHz,而实测结果分别为830ns、0.57Np及4.7 MHz。总体上,ANSYS模拟结果与实测结果较为一致。由此,模拟计算可为实际设计和加工提供指导。

In order to understand and obtain the whole structure RF characteristics of the disk-loaded accelerating tube,the redesigned axis-symmetric coupler was adopted to replace the real 3-D one during the calculation process by ANSYS.Much less computer sources and time were required to simulate the whole structure with only one single PC by taking full advantage of the structure＇s axis-symmetric characteristic.The accelerating tube for the BEPC Ⅱ linac was used as an example to validate this method.The ANSYS simulated filling time,attenuation factor and bandwidth are 856 ns,0.56 Np and 3.55 MHz respectively,while the experimental measured ones are 830 ns,0.57 Np and 4.7 MHz respectively.It can be seen that the ANSYS simulation and experimental measurement are consistent as a whole,and the simulation can provide very valuable reference for the real design and fabrication.