一种基于伸展线法的小孔径四极磁铁测量方法

A small aperture quadrupole magnet measurement method based on the single stretched wire method

针对目前多极磁铁孔径越来越小的发展趋势,搭建了一种基于单根伸展线法(Single Stretched Wire Method,SSWM)的磁测系统,该系统的主要优势是测量域所需空间小且运动模式灵活。基于该系统的优势及四极磁铁磁场分布的特点,尝试使用双曲线轨迹对四极磁铁靠近其四个极头的区域进行了扫描测量,并根据矢势在测量点分布的特性,提出了一种全新的数据分析方法,用以分析四极磁铁的梯度积分和高阶场误差。用该系统对一孔半径为11 mm、梯度大于100 T·m^(-1)的四极磁铁进行测量,测量结果表明高阶场误差测量重复性好于±1.5×10^(-4),能满足小孔径高梯度四极磁铁的磁场测量要求。

[Background]The trend towards increasingly narrow apertures in multipole magnets poses a challenge to many conventional measurement methods.Consequently,these methods'applicability in small aperture multipole magnets is limited.However,the single stretched wire measurement technique has emerged as a promising alternative due to its minimal space requirements within the measurement domain.Therefore,this technique is well-suited for accurately measuring magnetic fields in small aperture magnets.[Purpose]This study aims to introduce a novel approach for analyzing the gradient integral and multipole errors of the quadrupole magnet,to address the limitations associated with the current single stretched wire method(SSWM).[Methods]Firstly,a magnetic measurement system based on the single stretched wire method was constructed with two boasted key advantages:minimal space occupation within the measurement domain,and flexible motion modes.Then,leveraging these features,measurements of the four poles of a quadrupole magnet by employing a hyperbolic trajectory was acquired,and a new technique for analyzing both the gradient integral and multipole errors associated with the quadrupole magnet was developed.Finally,the feasibility of this SSWM was verified by comparing the results obtained from our system to those derived from the rotating coil method.[Results]Measurement results of a quadrupole magnet with the inscribed radius of 11 mm and gradient of 100 T⋅m^(-1) by SSWM show that the repeatability of three measurements is better than±1.5×10^(-4) which is less than one-third of the maximum value of multipole error of 5×10^(-4),so it can meet the measurement requirements.[Conclusions]The methodology outlined in this study for constructing the measurement system and analyzing the resultant data offers a practical and effective solution for the future magnetic field measurements of small aperture magnets.