摘要
采用不同的近似方法对用于聚焦带状电子束传输的偏置磁极周期会切永磁场进行了理论分析,得到了两种不同形式的解析表达式,分别适用于数值计算和理论分析.首先,为了对偏置磁极周期会切永磁铁进行快速而又精确地数值仿真,利用表面电流带模型对其进行等效,得到了其激励的偏置磁极周期会切永磁场的解析表达式,并借助算例说明了表面电流带模型应用于等效偏置磁极周期会切永磁铁开展优化设计的高效性.然后,为了便于在将来开展对带状电子束传输的理论分析,按传统方法将偏置磁极周期会切永磁场分为两部分,一部分是磁极的无偏置部分激励的周期会切磁场,基于已知的场分布对其采用待定系数法进行了求解,另一部分是磁极的偏置部分激励的非周期的边聚焦磁场,对其采用双层磁荷面模型等效磁极偏置部分的方法进行求解,分别得到了简明而又相对精确的解析表达式,这两部分表达式的叠加即为偏置磁极周期会切永磁场的解析表达式.这些结果可用于偏置磁极周期会切永磁聚焦带状电子束传输问题的研究.
The magnetic field excited by the offset-pole periodic cusped permanent magnet （OPPCPM） used for focusing the sheet electron beam has been approximately expressed in two different forms for the convenience of future numerical calculation and theoretical analysis, respectively. Firstly, the surface-current-sheet model has been used to approximate the OPPCPM, and an accurate expression has been obtained using Biot-Savart law. This expression would rather be applied to numerical calculation than theoretical analysis because of the complication. The optimization of entrance taper of the OPPCPM has been performed as an example of application of the expression, implying the high efficiency of the calculation brought by the expression. Secondly, to obtain simple expression of the magnetic field for the convenience of future theoretical analysis, the OPPCPM field has been divided into two parts： the periodic cusped magnetic （PCM） field component and the side-focusing magnetic field component. The expressions of the PCM field component have been obtained using the method of undetermined coefficient, while the expressions of the other one have been obtained using two-magnetic-charge-sheet model. The results are useful to study the transportation of the sheet electron beam in the offset-pole PCM field.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2010年第3期1726-1733,共8页
Acta Physica Sinica
基金
国家高技术研究发展计划(863)资助的课题~~
关键词
偏置磁极周期会切永磁场
表面电流带模型
双层磁荷面模型
带状电子束传输
offset-pole periodic cusped permanent magnetic field
surface-current-sheet model
two-magnetic-charge-sheets model
propagation of the sheet electron beam
