Wire Position Sensor for Controlling the Process of Electron Beam Layer-by-Layer Deposition: Modeling and Verification

One of the difficulties of performing electron beam deposition with wire material is positioning the filler wire relative to the electron beam. The accuracy of the positioning of the beam relative to the wire significantly affects heat input characteristics, the transfer of molten metal from the wire to the substrate, and, as a consequence, the nature of the formation of the layers. In this paper, a model of the formation of a bremsstrahlung X-ray radiation during an electron beam's interaction with a filler wire is developed and verified. We also present a model of a sensor for detecting the position of the filler wire relative to the axis of the electron beam. The sensor model establishes how the bremsstrahlung X-ray radiation changes depending on process parameters, such as: beam oscillation parameters, accelerating voltage, beam current, and beam diameter in the interaction spot, the diameter of the wire, the substrate materials and filler wire, and the wire's displacement from the center of beam oscillation.