1. The process of using a focused beam of electrons to heat materials to the fusion point.
2. A process in which a welder generates a stream of electrons traveling at up to 60 percent of the speed of light as it focuses the beam to a small, precisely controlled spot in a vacuum, and converts the kinetic energy into an extremely high temperature on impact with the piece being worked on.
3. A welding process which takes place in a vacuum.

Heat is produced by a focused electron beam that can produce welds having depth-to-width ratios of up to twenty to one.

Applications include welding of thin metal foils to thicker metal without burning, sealing of metal cans containing uranium fuel elements for reactors, and direct fusion welding of ceramic objects.