Independent support system for beam position monitors in HEPS
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摘要: 高能光源(HEPS)要求束流轨道稳定性达到0.1 μm。束流位置探测器系统(BPM)作为储存环的重要系统,其测量数据在监测和实现束流轨道稳定中具有重要作用,需要具有长期稳定性。为抑制由于机械振动、环境温度变化导致的机械形变等对BPM探头机械稳定性的影响,需为BPM探头设计独立稳定的支撑系统,使其具有较高的固有频率、较小的振动放大比和较小的温度形变。本文首先考虑温度形变,选取具有良好温度稳定性的Invar36合金作为支架的主体结构材料;为加工及安装方便,杆板结构选作支架模型,通过仿真测试寻找最优结构;利用ANSYS软件中拓扑优化寻找限制空间内实现最大固有频率的模型结构,为支架设计做指导;加工支架实物,并在实验室测量。支架实验室测量结果与仿真结果进行比较,进而优化安装方式。在四种安装方式下对支架进行测试,为支架在光源实地安装提供参考。Abstract: A beam orbit stability of 0.1 μm is required by the High Energy Photon Source (HEPS). As an important system of the storage ring, the beam position monitors (BPMs), together with the measured data, play an important role in the beam orbit monitoring and stabilization. Resolution of 0.1μm and long-term stability is required for the BPMs. In order to suppress the mechanical deformation caused by mechanical vibration and temperature variation, an independent and stable support system for the BPM-pick-ups is indispensable to have a higher eigen-frequency in lateral, a smaller vibration amplification ratio, and a minimum temperature deformation factor. In this paper, Invar36 alloy is selected as the main material of the support structure since it has good temperature stability. To ease manufacture and installation, the rod and plate structure is selected for the support prototype, and thorough simulation is done to find the optimal structure. With the methods of topology optimization in ANSYS, the structure prototype of the maximum eigen-frequency is found to guide the design of the support. The support is tested in the laboratory. Comparison between the measurements and the simulation results is made for installation improvement. Four methods of installation is tested and the results will provide reference for the support installation in the storage in the future.
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表 1 材料属性
Table 1. Properties of Material
material density/(kg/m3) Young's modulus/Pa thermal expansion coefficient/℃ structural steel 7850 2×1011 1.2×10-5 stainless steel 7750 1.93×1011 1.7×10-5 Invar 36 8050 1.41×1011 1.6×10-6 concrete 2300 3×1010 1.4×10-5 表 2 四种安装方式的测量结果
Table 2. Results of four contacted methods
mounting methods eigen frequency of lateral mode/Hz RMS of support top/nm RMS of ground/nm finite element simulation measurement bolted 60.7 30.2 97 21 board pre-grouted 60.7 36.7 41 21 partly grouted 60.7 37.2 40 21 fully grouted 60.7 40.6 25 21 -
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