纯永磁波荡器基波与谐波磁场的三维计算与测试

Fundamental and harmonic induction fields in PPM undulator

对标淮的纯永磁波荡器进行了三维磁场的有限元计算,给出了纯永磁波荡器的基波与谐波磁场的幅值与相位,并与测试结果进行对比,结果表明,标准的纯永磁波荡器谐波磁场幅值比基波幅值低两个数量级。

The standard pure permanent magnet (PPM) undulator has been analyzed by 3-dimensional electromagnetic computation software, the Modeller in Opera3D. The amplitude and phase angle of fundamental and harmonic induction fields in it are given for different air gaps. They show that all harmonic induction fields in standard PPM undulator are two orders lower than their fundamental induction field. This conclusion is verified by the related magnetic measurements to one standard PPM undulator in optical klystron with 0.5mm×1mm Hall probe. The paper also presents comparisons between theoretic results with analysis equation as well as 3D Finite Element computations and magnetic measurement with hall probe. In furthermore, inserted very small airgaps along beam direction in PPM undulator, leaving space for shimming optimization, are conducive to better radiation performance.