166.6 MHz超导腔加强筋结构的多物理场耦合仿真

Multi-physics field coupled simulation of 166.6 MHz superconducting cavity stiffener

高能同步辐射光源加速器的166.6 MHz超导腔采用4.5 K饱和液氦浸泡冷却,其内导体与小束管之间设计有加强筋以改善超导的应力分布,加强筋会影响气泡排出,气泡聚集过多会降低液氦冷却效果,有引发失超的风险。使用Fluent、Hfss软件对超导腔内导体附近的流场进行了流动/传热/电磁多物理场耦合仿真,研究了加强筋顶部开孔设计对气泡流动以及换热效果的影响。结果表明:加强筋顶部开10 mm、20 mm方孔时气泡排出比较顺利,内导体EM面最高温度、平均温度相差较小,相对误差分别为0.5%和0.4%。加强筋顶部不开孔时会在顶部带来较厚的气泡堆积、较大的温度梯度并抬升内导体温度,最高温度约6.41 K,但仍可以保证超导腔处于超导温区。

166.6 MHz superconducting cavity is used in the High Energy Photo Source,which is cooled by 4.5K saturated liquid helium.A stiffener was designed to improve the stress distribution between the inner conductor and the small beam pipe,which will affect bubble discharge,too many bubbles may reduce the cooling effect of liquid helium and cause the quench.A coupled electromagnetic-flow-thermal multi-physics simulations were performed for the flow field near the inner conductor of superconducting cavity to investigate the effect of the top hole of the stiffener on the bubble flow and heat transfer using Fluent and Hfss software.The results show that the bubbles are discharged more smoothly when 10 mm and 20 mm square holes are opened on the top of the stiffener,and the maximum temperature and average temperature of the EM surface of the inner conductor differed less,with relative errors of 0.5%and 0.4%,respectively.For the stiffener with no hole on the top,a thicker accumulation of bubbles will be fromed which will a larger temperature gradient and raise the temperature of the inner conductor,the maximum temperature is about 6.41 K,but it can still ensure that the superconducting cavity is in the su-perconducting temperature region.