Since Nicoli Tesla first applied for patents on a light source based on electron beam bombardment heating of graphite in evacuated glass bulbs, electron beam technology has advanced wherein practical production joining by this method is gaining industry-wide acceptance.Men of importance who followed Teslas concept of utilizing this energy source as a working tool were K. H. Steigerwald of the Carl Zeiss Foundation in West Germany and J.R. Pierce, author of a technical book on electron beam optics.