[en] The invention is concerned with an electron gun for high radiant power. It is applicable to large irradiation plants for vacuum metallization. The electron gun has a rated capacity in the range from 60 kW to more than 1200 kW. Its electron beam results from a space-charge-limited emission current whose power can be controlled over the whole power range from 10% to 100% of rated capacity by means of an axially adjustable anode. A beam lens with a fixed focal length is used in such a way that there is no aperture enlargement. The electron gun operating with constant acceleration voltage consists of an axially adjustable anode with a conical angle from 60⁰ to 120⁰, a cathode with a conical angle from 140⁰ to 170⁰, and a focussing electrode with a conical angle from 130⁰ to 160⁰. The anode-sided pole shoe of the magnetic beam lens which has no water cooling is fixed to the anode which is made of high-temperature resistant material. The unit pole shoe-anode can be moved axially. Furthermore it is advantageous to use a control valve for maintaining the pressure in the area of the anode (1 to 3 x 10^-4 torr) which is necessary for gasfocussing of the electron beam