Low aberration permanent hexapole magnet for atom and molecular beam research
Low aberration permanent hexapole magnet for atom and molecular beam research
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DOI：
10.1063/1.1753093
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发表时间：
2004-06-01
影响因子：
1.6
通讯作者：
Ellis, J
中科院分区：
文献类型：
--
作者：
Dworski, S;Alexandrowicz, G;Ellis, J
我们提出了一个800毫米长，4.80毫米的孔，1.32 T极尖场永久六极（六极）磁铁系统具有极低的场像差的细节。该组件被开发为用于剑桥He-3自旋回波光谱仪的原子光学元件。我们的12段磁体是著名Halbach设计的改进版本，其中我们改进了极片形状以改善磁场特性。进行半解析模拟和有限元建模来优化极片形状，以最大化场强，同时最小化高阶多极像差。高精度的加工和组装技术被用来构建该装置和合成场进行了测量。1.25 T的测得的极尖场与模拟（5%的误差）和测得的像差（比使用传统设计的理想12段系统理论上可能的像差小至少5倍）非常一致。最后，在我们的谱仪中，作为一个复合磁透镜，六极磁铁的应用，用于分析表面散射的He-3原子从偏振入射光束的核自旋。(C)2004年，美国物理学会。
We present details of an 800-mm-long, 4.80 mm bore, 1.32 T pole-tip field permanent hexapole (sextupole) magnet system with exceptionally low field aberrations. The assembly was developed as an atom optical element for use in the Cambridge He-3 Spin-Echo Spectrometer. Our 12 segment magnet is an improved version of the well-known Halbach design, in which we refine the pole piece shape to improve the field characteristics. Semi-analytic simulations and finite element modeling were performed to optimize the pole piece shape, in order to maximize field strength while minimizing higher order multipole aberrations. High precision machining and assembly techniques were used to construct the device and the resultant field was measured. The measured pole-tip field of 1.25 T is in good agreement with the simulations (5% error) and the measured aberrations that are at least 5 times smaller than those theoretically possible with an ideal 12 segment system using the conventional design. Finally, the application of the hexapole magnet was demonstrated in our spectrometer, as a composite magnetic lens, used to analyze the nuclear spin of surface-scattered He-3 atoms from a polarized incident beam. (C) 2004 American Institute of Physics.