强流离子注入机加速管的聚焦特性研究

Study on focusing characteristic of acceleration tube in high current implanter

讨论了三间隙强流离子加速管的聚焦特性,计算了各种能量下离子束聚焦情况,并分析了抑制空间电荷效应所需要的电场强度。最后总结了三间隙加速管设计和调试应注意的问题。

The accelerating tube is one of the most important parts in high current implanter which provides the desired energy and focusing for ion beam.The factors affecting focus characteristic in high current implanter with three gap acceleration tube are discussed. focusing degrees of different energy ion beam are computed, and the electric field required to prevent beam expansion due to space charge effect are analyzed. The beam envelope inside the three acceleration gap shows a decrease of the beam radius with the increase of the accelerating voltage ratio up to the optimal value. Beyond this optimal value the beam lines make a crossover with the axis of the accelerating tube. 