Design and Development of Focusing System for Electron Beam Powder Bed Fusion Process

Electron beam powder bed fusion (EB-PBF) is an integration of electron beam (EB) technology and a powder management system (PMS) with three-axis motion. The EB gun produces a collimated beam, which helps in melting powder materials. The EB is generated by a cathode, confined by the grid, and accelerated by the anode. Further, focusing coil and deflection coils are used to focus the beam and move the beam over the worktable. Considering the requirement of a small beam diameter and circularity of the beam, the design of the focusing coil is crucial. This chapter presents a customized design of the focusing coil that can converge the EB to a very sharp point. An analytical design has been performed for magnetic field calculation and gyro-radius calculations for optimal focusing. Further, the fabricated coil has been tested for focusing and found that it can generate a beam of less than 1 mm average diameter at a distance of 710 mm from its center.