用于HEPS-TF低温波荡器的过冷液氮循环系统

Design of subcooled liquid nitrogen circulation for HEPS-TF CPMU

在高能同步辐射光源验证装置(HEPS-TF)的插入件系统中,将要研制一台基于镨铁硼永磁铁的低温波荡器(CPMU)。低温波荡器要求磁铁磁极阵列工作温度要在85 K以下,同时整个大梁轴向的温度梯度不超过1.5 K/m。经过理论计算,低温波荡器在有束流情况下的热负荷约660 W@80 K。为冷却低温波荡器大梁磁结构,设计了一套过冷液氮闭循环迫流冷却系统。为了确保磁铁有更好的低温效果和温度均匀性,低温波荡器内大梁采用了双通道冷却设计。最后,根据低温流程设计了可行的机械结构,称其为液氮过冷器冷箱。

A PrFeB-based Cryogenic Permanent Magnet Undulator（ CPMU） will be designed for preresearch of the High Energy Photon Source（ HEPS-TF）. The CPMU magnetic arrays need to be cooled to liquid nitrogen temperature. Based on our calculation,the total heat load at working temperature is about 660 W. To achieve the cryogenic temperature,we designed the closed-loop subcooled liquid nitrogen circulation cooling system. In addition,it has to prevent any large temperature gradient（ below 1. 5 K/m） along the magnet assembly,which might induce additional magnetic errors. For better cryogenic performance and temperature uniformity,along each CPMU in-vacuum girder two through-holes will be drilled as double refrigerant channels. Engineering design of the sub-cooler cold box was already finished.