Abstract This paper shows the influence of the local magnetic forces on the mechanical analysis of a superconducting dipole magnet employing Nb3Sn technology. On high field magnets, the iron yoke has several functions: (1) magnetically, it increases the magnetic field in the bore and it has a shielding function; (2) mechanically, iron helps on the coil pre-load, transferring the mechanical forces provided by the external support structure. In many Nb3Sn magnets for particle accelerators, the cable is wound around an iron piece. As a consequence, the magnetic force on the iron can play an important role on the coil stress. The magnetic forces on the iron components can be computed using several different methods and the goal of this paper is to compare three expressions for the Maxwell stress tensor to compute local magnetic forces on iron considering a B-H curve. The influence of these forces on the mechanical behavior of the magnets is then analyzed, taking into account the uncertainties in determining their correct distribution. To achieve this goal, a numerical tool to perform Finite Element Analysis (FEA) was developed using vector potential formulation with first order nodal elements. The solution obtained from the magneto-static problem was used to calculate and compare the magnetic force distribution. The contributions from the Lorentz forces on coils are also taken into account in the mechanical analysis and are compared to the ones computed by using the Maxwell stress tensor on coils.

中文翻译：

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用超导磁铁对铁力分布进行机电建模

摘要 本文展示了局部磁力对采用 Nb3Sn 技术的超导偶极磁体力学分析的影响。在强磁场磁铁上，铁轭有几个作用：（1）磁性，它增加了孔中的磁场，具有屏蔽作用；(2) 在机械上，铁有助于线圈预加载，传递外部支撑结构提供的机械力。在许多用于粒子加速器的 Nb3Sn 磁铁中，电缆缠绕在铁片上。因此，铁上的磁力可以对线圈应力起重要作用。可以使用几种不同的方法计算铁部件上的磁力，本文的目的是比较麦克斯韦应力张量的三个表达式，以计算考虑 BH 曲线的铁上的局部磁力。然后分析这些力对磁体机械性能的影响，同时考虑确定其正确分布的不确定性。为了实现这一目标，使用具有一阶节点元素的矢量势公式开发了一种用于执行有限元分析 (FEA) 的数值工具。从静磁问题中得到的解用于计算和比较磁力分布。