Abstract: The invention concerns an electron gun for the production of an electron beam designed primarily for welding workpieces and including, in a frame, the mechanical facilities required for holding in a coaxial position and electrically insulating a cathode, a filament, a wehnelt and an anode.Gun featured by the fact that the cathode is held by mechanical systems in the coaxial position via several rods made of conductive material, one end of these rods being rigidly fixed with respect to the frame, the other end being applied against the outer wall of the disc shaped cathode, thus forming a positioning clamp for said cathode.The structure allows for the efficient cooling of the internal parts of the gun.