高质量分辨率分析磁铁磁场测量及垫补

Measurement and Optimizing of Magnetic Field for High Mass Resolution Analysis Magnet

摘要: 串列加速器升级工程在线同位素分离器（BRISOL）需对同质异位素进行分辨，谱仪设计质量分辨率为20 000。本文介绍了BRISOL分析磁铁的磁场测量及垫补。为达到20 000的质量分辨率，BRISOL谱仪采用由2块小铁和2块大铁组成的异能大、小铁结构消除能量色散。主分析磁铁磁场均匀性要求好于5×10^-5，采用表面线圈对磁场进行垫补。垫补后，好场区范围内积分场均匀性由3×10^-4提高到了3.5×10^-5。

Abstract: The mass resolution of Beijing Radioactive Ion Beam Facility Isotope Separator On-line (BRISOL) is 20 000 for the separation of isobar beam. The field measurements and field optimizing were presented in this paper in detail. To reach the high mass resolution power of 20 000, a bi-energy system with two small dipoles and two big dipoles was used to reduce energy dispersion which is too large to get high mass resol ution power. The magnetic field uniformity of the analysis magnet must be better than 5×10^-5. The surface coils were set on pole face to improve the magnetic field homogeneity. The integral field uniformity with surface coil was optimized from 3×10^-4 to 3.5×10^-5.