Surfaces to a strong secondary emission of electrons and method of manufacture of these surfaces

摘要

473,398. Electrode materials. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Feb. 8, 1937, No. 3725. Convention date, Feb. 10, 1936. [Class 39 (i)] A surface having a high secondary emission comprises a layer of carbon of high adsorption having adsorbed to it one or more of the metals magnesium, calcium, barium and strontium. In one method a supporting body such as nickel is coated with one or more oxides or hydroxides of the specified metals, such as magnesium oxide, and is then heated by high frequency in an atmosphere of a hydrocarbon such as acetylene or methane. The surface is subsequently heated in a vacuum to 900-1000‹ C., when the partial reduction of the oxide by the carbon produces metal which is adsorbed to the carbon. Five or six secondary electrons may be emitted per primary electron. The Specification as open to inspection under Sect. 91 refers to the use of one or more metals of the second principal group of Mendeleef's periodic table, of atomic number greater than 4. This subject-matter does not appear in the Specification as accepted.