A special continuously pumped x-ray tube has been developed for producing high intensities of characteristic K-emission lines. The rotating primary target consists of a gold-plated copper cylinder, which is water-cooled. The conical secondary target is placed inside the primary target and close to it so as to achieve a high output yield. With the tube windows used at present, wavelengths between 0.1 and 0.5 Å can be produced by choosing the appropriate elements for the secondary target. To obtain a high purity of the radiation, the tube voltage should be less than three times the minimum excitation potential for the K radiation in question. The x-ray yield is 108−109 quanta/mA-sec-sr.