衍射极限储存环注入薄切割磁铁设计仿真与磁场测量

Design simulation and magnetic field measurement of eddy-current type thin septum magnet for beam injection of diffraction limited storage ring

衍射极限储存环(Diffraction-Limited Storage Ring,DLSR)光源具有高亮度、高稳定性和极佳横向相干性等特点;快冲击器(如strip-line kicker)搭配薄切割磁铁在轴注入的方式解决了DLSR中传统局部脉冲凸轨方式束流无法注入的难题。对切割板小于1 mm的涡流板型切割磁铁开展理论计算、仿真分析、制造组装和磁场测量等研究,利用磁场分析软件Opera 2D/3D对薄切割磁铁主漏场及涡流场随时间演变等过程进行分析,重点关注薄切割板结构和工艺优化。三维动态计算和磁场相关参数实测表明,该薄切割磁铁切割板外3 mm处主漏场积分峰值比优于0.1%的物理指标,为未来先进光源储存环注入设计奠定了一定基础。

[Background]Diffraction-limited storage ring(DLSR)light source is considered to be promising candidate for future light sources within higher brightness,better transverse coherence and better stability.The challenge of DLSR design is how to achieve the ultra-low beam emittance with acceptable nonlinear performance.Short-pulse kickers such as strip-lines along with thin septum magnet could support on-axis injection of DLSR,while the traditional off-axis injection becomes inadequate.[Purpose]This study aims to design and measure the magnetic field measurement of eddy-current type thin septum magnet for beam injection of diffraction limited storage ring.[Methods]The scheme of eddy-current type thin septum magnet(the thinnest thickness is 0.9 mm)was adopted,and the magnetic core was laminated silicon steel sheet.Theoretical analysis and simulation of the main field and leakage field that decayed with time were carried out by using Opera 2D/3D magnetic field analysis software.Special attention was paid to optimize the structure and processing of the septa.Point coil,long coil,integrator and oscilloscope were used to measure the magnetic field of the assembled thin septum magnet.[Results]The experimental measurement data and 3D dynamic calculation results show that the integral peak ratio of leakage field at 3 mm away from the septa is less than 0.1%with respect to the physical requirement.[Conclusions]This study lays a foundation for injection design of future advanced light source storage ring.