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 Tesla's 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. The first practical welding applications of this process were accomplished by J. A. Stohr@ who announced the first electron beam welder at the Technical Symposium of Fuel Elements in Paris@ France in 1957. W. L. Wyman of General Electric Hanford Laboratories is credited with developing the first electron beam welder in the United States at about this same time period. Electron beam welding has gained rapid recognition in the materials joining field@ particularly in the aerospace industry. More than 200 electron beam welding machines have been sold as of this writing and equipment manufacturers report an increasing activity and interest in this type of welding equipment. The controversial subject of high vs. low voltage electron beam welding has faded into the background and this topic is no longer considered of prime importance in electron beam welding technology.