During electron beam welding the high energy concentration causes the material to melt, forming plasma. The escaping plasma creates a channel as it “drills” into the depth of the workpiece and forms the welded seam as it cools. The sequence shown has been acquired using 9,000 fps with the exposure matched to the actual welding process. A commonly applied technique is to oscillate the beam via electromagnetic coils. A circular suspension of diameter 0.4 mm was used here. At 10 Hz the electron beam moves the plasma channel, while at higher frequencies (e.g. > 500 Hz) the electron beam increases the plasma channel. At the bottom left, the open plasma channel can be seen very well, while the electron beam moves at the edge.
Courtesy of Westfälische Hochschule Gelsenkirchen Bocholt Recklinghausen, Fachbereich Maschinenbau und Facilities Management.