关于闭合及偏置PCM结构约束带状电子注可行性的研究

Research on feasibility of closed and offset PCM focusing structures for sheet electron beams

通过理论分析和数值计算证明了闭合PCM结构可以在窄边和宽边两个横方向上对接近真实情形的带状注束流进行有效约束,实现电子注的长距离稳定传输.提出了匹配电子注宽边方向横向磁聚焦力与带状注内空间电荷力的方法,这可用于确定闭合PCM聚焦结构的纵向周期长度以及截面尺寸.所做计算还显示出闭合PCM结构横截面的宽边方向尺度可以独立调节以达到最优的匹配.此外,进一步证明了偏置PCM结构不能有效约束带状电子注.本工作表明闭合PCM结构用于限制带状注束流具有很大潜力并且有助于指导实际的工程实践.

Using theoretical analysis and numerical calculation, it has been demonstrated that the closed periodic cusped magnetic （PCM） field can effectively confine the sheet electron beam in two transverse directions simultaneously to realize the stable long distance transport, where the beam cross-section has an attainable shape of the state of the art. Moreover, the method for matching the transverse magnetic focusing force and the inner space charge force in the wide dimension of the sheet beam is given, which can be used to determine the longitudinal periodic length and the cross section shape of the closed PCM structure. The calculation has also shown that the optimum focusing can be acquired through adjusting the width of the closed PCM structure independently. And besides, it has been proven that the offset PCM structure is not a good choice for sheet beams’ confinement. The work presented in the paper indicates that the closed PCM structure is very promising, and it’s helpful for guiding the practical engineering design.