A New Method to Focus SEBs Using the Periodic Magnetic Field and the Electrostatic Field

In this paper, a novel method, named PM-E, to focus the sheet electron beam (SEB) is proposed. This new method consists of a periodic magnetic field and an electrostatic field, which are used to control the thickness and width of the SEB, respectively. The PM-E system utilizes this electrostatic field to replace the unreliable By,off, which is a tiny transverse magnetic field in the PCM that confines the SEB’s width. Moreover, the horizontal focusing force of the PM-E system is more uniform than that of the conventional PCM, and the transition distance of the former is shorter than that of the latter. In addition, the simulation results demonstrate the ability of the PM-E system to resist the influence of the assembly error. Furthermore, in the PM-E system, the electric field can be conveniently changed to correct the deflection of the SEB’s trajectory and to improve the quality of the SEB.