JPS6412487A - Surge absorptive element - Google Patents

Abstract

PURPOSE:To shorten a discharge delay time by sticking a K element and/or a K compound, and a mixture which contains elements and/or compounds of specific values or below in their work function besides, on surfaces of discharge electrodes. CONSTITUTION:Opening parts on both ends of an insulation tube 1 are sealed by discharge electrodes 2 and 3. Discharge parts 2a and 3a of both the electrodes 2 and 3 protruded inside the tube are disposed to face with a prescribed gap 4 according to a discharge voltage, and a gas is sealed in the tube. A K element and a K compound, and a mixture which contains one or more species of elements and/or compounds (except K) of 3.6eV or less in their work functions besides, are stuck on surfaces of the electrodes 2 and 3. The abovementioned K element and K compound are natural radioactive materials. Elements and compounds of 3.6eV or less in their work functions are used to promote electron radiation of the natural radioactive materials and to lower a vapor pressure and to obtain a high melting point. A difference of clearness in the discharge starting voltage can be thus decreased, and stability and reproducibility of the discharge starting voltage can be improved in a scale of industrial production.