LOCAL THERMIONIC EMISSION FROM COVERED SURFACES OF ELECTRODES.

The operating conditions of thermionic converters have been examined with respect to the oxygen content and the barium content in the surrounding atmosphere. Some of the effects that occur under such conditions at the surface of hot electrodes are shown by pictures on the screen of an emission microscope. The influence of the partial pressure of additives is demonstrated first by a covered cermetelectrode composed of spheres of uraniumdioxid which are embedded in a molybdenum sponge and second by a sample of polycrystalline molybdenum.