Pulsed-wire system for undulator measurement

Purpose More undulators are required of HEPS in future.The efficiency of traditional Hall-probe measurement method is relatively low,which is difficult to meet the measurement needs of large quantities of undulators.In order to improve debugging efficiency,the pulsed-wire method is required further improvement.Methods A pulsed-wire method is an effective method to achieve magnetic field distribution through narrow aperture of undulator.The pulsed-wire method works by sending a square current pulse through the wire,which will induce an interaction with the magnetic field due to the Lorentz force.This force causes the wire to be displaced,and this displacement travels along the wire in both directions as an acoustic wave.Measurement of the displacement in the wire over time using a motion detector yields the first or second integrals of the magnetic field.Results The accuracy and repeatability are the important requirements.The repeatability of the first field integral of the pulsed-wire system is better than 1‰which meets the design requirements.Conclusions This paper illustrates the effectiveness of pulsed-wire system by test results.Through comparison,the accuracy of the system is proved.It provides a new important measurement system for undulators in future.

High-accuracy stretched-wire measurement system for cryogenic permanent magnet undulator(CPMU)in High Energy Photon Source(HEPS)

A new stretched-wire system is built for a cryogenic permanent magnet undulator in High Energy Photon Source Testing Facility.The system has two functions:integral field measurement and magnet gap measurement.Integral field measurement and gap measurement are important for evaluation and optimization of the magnetic performance of the undulator in cryogenic-vacuum environment.Two high-precision,high-load motion stages are used for accurate positioning.A special fix structure of stretched wire is adopted for vacuum environment.To reduce the deflection of the 3-meter-long wire,constant tension is maintained along the wire.The measurement repeatability of field integral and magnetic gap is the key performance which depends on the stability of wire and suppression of the electric noise.Strategy of improving the measurement accuracy and stability is presented.

脉冲线测量波荡器磁场的研究

介绍脉冲线测量波荡器磁场一、二次积分分布的原理和一套较高精度的脉冲线测量系统的研制,分析了传感器、实验环境、线的张力和波的反射性等因素对测量精度的影响。该系统对5周期波荡器模型的磁场测量结果与高精度Hall探头测量值作了比较,结果满意。

脉冲紧线磁轴测量方法中金属丝下垂的影响分析

脉冲紧线磁轴测量方法中绷紧金属丝线在自身重力作用下产生的下垂会对测量结果产生重要影响。文中对丝线的下垂曲线进行了推导,获得了丝线下垂曲线方程,并且通过实验进行了验证。在此基础上,建立了丝线振动数值分析模型,对实际测量布局中金属丝下垂产生的信号进行了系统而详细的分析,得出丝线下垂对磁轴测量结果的影响。为减小丝线下垂引入的测量误差,可以通过对测量结果进行修正、采用新的定位方法、搭建竖直测量平台三方面着手。

基于悬丝法的螺线管磁轴测量信号处理技术

针对螺线管磁轴测量中的悬丝位置、测量信号失真、磁轴偏轴和磁轴倾斜信号的分离数据处理要求等问题,采用一种高偏置消除的信号检测与测量方法,并对探测器采用了相关的恒定驱动技术,进一步提高了信号产生的稳定性及抗干扰能力,研制了一种可以获得比较直接的悬丝振动信号的测量系统,解决了单纯采用交流耦合隔直滤波放大器或带通滤波放大器不能获得完全准确的测量信号的问题,确保了在较高的直流偏置下获得没有畸变的较小测量信号,消除了测量信号中低频分量基线倾斜及其中起伏的影响,并实现了磁轴偏移和磁轴倾斜信号的分离,极大地提高了螺线管线圈磁轴的测量灵敏度,实际测试结果显示测量灵敏度提高约1个量级。

小开口磁器件内通电悬丝形变有限元分析方法

针对测量小开口磁器件磁场的脉冲悬丝法无法建立三维磁场中悬丝形变解析推导以及无法应用于磁场结构设计优化的问题,依据磁场中通电悬丝运动的基本原理,提出基于有限元的永磁器件结构参数和磁场分布改变的通电悬丝形变分析方法。建立磁件-悬丝系统的电流场、磁场、应力场三维耦合仿真模型,用耦合场有限元计算替代近似的解析求解,对不同永磁磁件以及周期磁场中悬丝的形变进行对比,分析通电悬丝在均匀或各向异性周期磁场中各方向的形变规律,并给出建模和悬丝形变分析的实例。结果显示悬丝系统有限元仿真平台建立了悬丝形变和磁场分布之间的联系,可用于小开口磁件的结构设计和其内磁场分布规律的改善。

脉冲悬丝测磁技术研究的发展

脉冲悬丝法是基于磁场中悬丝通电产生运动的原理,通过位移传感器测量悬丝位移,来反映带电粒子束通过磁场时所受影响,可对具有小开口和较大长/径比的内腔磁场器件的性能进行测量和校正。结合典型脉冲悬丝法的理论模型,阐述了脉冲悬丝法磁场测量技术的基本原理。总结了国内外脉冲悬丝技术的相关研究,概括了脉冲悬丝法的发展和已取得的成就,探讨了脉冲悬丝法存在的局限和该技术的发展趋势与研究方向。

脉冲线积分场测量系统的研制

介绍了脉冲线测量插入件磁场一二次积分的原理和测量装置的组成,分析了重力、噪声和反射波等因素对测量精度的影响,并采用对称安装金属线、夜间测量、油滴吸收反射波等方法减小了这些因素对测量的影响。脉冲线测量系统的测量结果与霍尔点测法相比符合得较好。利用该装置对实验室即将投入应用的电磁型圆极化波荡器进行了测量,验证了校正线圈和主线圈电流之间的关系。