MAFIA程序在小型短四极磁铁设计中的应用

为设计用于加速器的小型短四极磁铁结构 ,运用MAFIA程序对小型短四极磁铁进行三维模拟计算 ,研究了当磁铁机械长度和内接圆半径可比拟时 ,端部漏磁对磁铁有效长度的影响 ,根据场计算修正了原设计的机械长度 ,满足了磁铁有效长度的要求。模拟还发现 :短极颈四极磁铁励磁线圈本身的磁场直接影响四极磁铁极端面附近的磁场分布。实际测量了四极磁铁沿长度方向的磁场分布 ,模拟和实测结果相当吻合。计算表明 :有效长度大于内接圆直径约 5倍时 ,计算机械长度的经验公式比较准确

MAFIA analysis of miniature short quadrupole magnet design

The 3-D field distribution in a miniature short quadrupole magnet for accelerator was calculated using the MAFIA code. The analysis studied the effect of field leakage at the pole ends on the effective length when the mechanical length of the quadrupole magnet was comparable to its inscribed circle radius. The MAFIA simulation results show that the modified mechanical length satisfy the requirement of the magnet effective length. The simulations also show that the magnetic field from the excitation windings directly influences the field distribution at the end of the quadrupole magnet if the pole neck is too short. The MAFIA simulation results agree well with experimental results. The computational results from empirical formulas are accurate when the effective length was about 5 t