Simulating analysis on electric field flatness of deformed superconducting elliptical cavity for CSNS-II linac
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摘要: 超导椭球腔是一种通过冲压零件和电子束焊接而成型的薄壁结构,在加工过程中存在不可避免的形变,如单元倾斜、偏轴,单元长度偏差,从而影响椭球腔的轴向电场平坦度,进而降低椭球腔的运行电场梯度。因此,在椭球腔加工成型后要进行预调谐处理。椭球腔预调谐是通过对椭球腔整形,包括倾斜和偏轴矫正,单元长度矫正,以达到提高轴向电场平坦度的目的。采用COMSOL多物理场耦合软件对CSNS-II(China Spallation Neutron Source Phase II)超导椭球腔可能存在的形变进行了仿真计算,研究了各单元形变量对电场平坦度的影响,分析了腔体调谐位移量对电场平坦度的影响,为椭球腔预调谐提供数据参考,也为预调谐机的设计研制提供指导。另外,确定了椭球腔机械形变的要求,确保椭球腔机械加工质量满足CSNS-II升级的实际工程需求。Abstract: Superconducting elliptical cavity is a thin-walled structure formed by stamping parts and electron beam welding, and there are inevitable deformations in the machining process, like cell tilt, cell off-axis and cell length deviation. Thus, the axial electric field flatness of the elliptical cavity is affected, and then the operating electric field gradient is reduced. Therefore, pre-tuning is necessary after the elliptical cavity finish processing. The pre-tuning of elliptical cavity is to improve the axial electric field flatness by reshaping the elliptical cavity, including the correction of cell tilt and off-axis, and the correction of cell length. This paper presents the simulation of possible deformation of elliptical cavity by COMSOL multiphysics software and analyzes the influence of cell deformation and tuning displacement on electric field flatness is analyzed, it can provide data reference for CSNS-II elliptical cavity pre-tuning and guide the designing and developing of pre-tuning machine. In addition, it determines the requirements of mechanical deformation to ensure the machining quality of elliptical cavity to meet the actual engineering requirements of CSNS-II.
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Key words:
- superconducting elliptical cavity /
- electric field flatness /
- tilt /
- off-axis /
- extrusion /
- stretching /
- tuning
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表 1 椭球腔机械加工形变要求
Table 1. Deformation requirements in machining elliptical cavity
tilt/mm off axis/mm extrusion or stretching/mm end cell 1 1 0.06 sub-end cell 1 1 0.06 middle cell 2 1 0.06 pre-tuning function ○ × ○ -
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