Abstract: Disclosure is made of an electron beam welding gun, wherein an anode unit is connected to a cathode unit having a sealed housing, in which there is arranged a cathode assembly. Said cathode assembly comprises a high voltage tubular insulator, whereupon there are mounted sealed leads. The inside of said sealed housing is filled with a liquid dielectric and cooled by a cooler. At least part of the outer surface of the high-voltage tubular insulator is part of the surface of the sealed housing's internal cavity.

Abstract: Disclosure is made of a cathode assembly of an electron beam welding gun, wherein in a holder's sleeve, which is mounted an a current lead, there is arranged a disc cathode. Arranged in the cavity of said current lead, coaxially therewith, are two more current leads. The latter two current leads are concentric to each other; in said current leads there is secured a flat coil with a central end bent at a perpendicular to the coil's plane. Said central end, bent at a perpendicular to the coil's plane, is corrugated along its axis and installed in a current lead constructed as a rod having a stepped cavity extending along the rod's axis. The outer turn of said coil is arranged in another current lead which envelops the above-mentioned current lead and is constructed as a tube with an internal annular recess at its end, which receives the outer turn of said coil.

Abstract: Disclosure is made of a cathode assembly of an electron beam welding gun, comprising a current lead, wherein there is arranged a heating cathode which is coaxial with said current lead. Next to said heating cathode and coaxially with it, in a holder's sleeve there is arranged a disc cathode. The holder's sleeve is provided with a central orifice in its bottom to receive the disc cathode. On the internal surface of said sleeve, on the side opposite to the bottom, there is provided a cone-shaped recess widening towards the disc cathode, which recess receives a split ring of a refractory material, intended to press said disc cathode against the bottom of the holder's sleeve.