HIAF随机冷却系统slot-ring型pickup/kicker及相应合路器/功分器的设计与仿真

Design and Simulation of Slot-ring Type Pickup/Kicker and Power Combiner/Splitter for HIAF Stochastic Cooling System

为降低束流发射度,提高束流强度,得到高品质的束流,强流重离子加速器装置(HIAF)高精度环形谱仪(SRing)将建造随机冷却系统。随机冷却系统的关键硬件pickup/kicker在一定程度上决定了其冷却效率。本工作讨论了随机冷却系统pickup/kicker的具体作用及设计指标,介绍了分路阻抗概念。SRing随机冷却系统采用周期性单元结构slot-ring模型,利用高频结构仿真(HFSS)软件对其进行建模并仿真优化。通过对不同结构参数进行扫参,确认了slot-ring结构各参数对pickup/kicker分路阻抗值的影响。仿真结果表明,slotring结构有较高的分路阻抗,适用于SRing随机冷却系统。同时,考虑到pickup/kicker工作带宽内分路阻抗的平坦度,提出了采用不同尺寸slot-ring结构进行组合的方式来优化其平坦度。最后设计并加工实测了该slot-ring结构相匹配的十六路功率分配器/功率合成器,实测结果表明:该功分器/合路器具有各端口输出幅度平坦度较好、隔离度大、插入损耗低、电压驻波比小等特点,满足SRing随机冷却系统的要求。

In order to reduce beam emittance,improve beam intensity and obtain high quality beam,a stochastic cooling system will be constructed for the high-precision Spectrometer Ring(SRing) in the High-Intensity heavy ion Accelerator Facility(HIAF).The pickup/kicker plays a significant role in the stochastic cooling system and determines its cooling efficiency to a certain extent.The paper discusses the significant function and design specification of the pickup/kicker of the stochastic cooling system,and introduces the concept of shunt impedance.The periodic element slot-ring structure is adopted for the SRing stochastic cooling system,and high frequency structure simulation software(HFSS) is used for modeling and simulation optimization.The effect of slot-ring parameters on shunt impedance of pickup/kicker is studied by sweeping different structural parameters.The simulation results show that the slot-ring structure has high shunt impedance and is suitable for SRing stochastic cooling system.At the same time,considering the flatness of the shunt impedance in the whole operating bandwidth of pickup/kicker,a combination of slot-ring structures of different sizes is proposed to optimize its amplitude flatness.Furthermore,a 16-way power splitter/combiner for the slot-ring structure is designed and fabricated.The measured results show that the combiner/splitter has the performance of a good output amplitude flatness,large isolation,low insertion loss,low voltage standing wave ratio and so on,which meets the requirements of the stochastic cooling system.