Some effects of slow electron bombardment in thermionic valves

This paper describes first the general features of the interaction between slow electrons and solids upon which they impinge. The threshold electron energies for the absorption of electrons, for the appearance of secondary emission and for decomposing the bombarded solid have been measured for a number of compounds. The values are quoted and are related to the optical absorption bands of the compounds. The effects on valve characteristics and on cathode emission are described briefly, when such compounds are present on the valve electrode surfaces.