Accession Number : ADA183643

Title :   Formation and Decomposition of Sulfur Compounds in Dispenser Cathodes.

Descriptive Note : Technical rept.,

Corporate Author : AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS

Personal Author(s) : Lipeles,Russell A

PDF Url : ADA183643

Report Date : 01 Jul 1987

Pagination or Media Count : 22

Abstract : Formation of sulfur compounds during cathode processing and generation of sulfur during cathode operation were examined using thermodynamic data. Sulfur compounds can be formed in dispenser cathodes exposed to a source of hydrogen sulfide (such as stainless steel parts used in processing in dry hydrogen at 1200 C). The hydrogen sulfide then reacts with the cathode impregnant to form barium and calcium sulfides. Those sulfide contaminants, in the cathode, thermally decompose during cathode activation and operation, resulting in sulfur contamination of the emitting surface and causing low cathode emission. Based on this mechanism, high sulfur surface coverage can be attributed to sulfides in the impregnant. To avoid sulfur contamination, the presence of sulfides should be avoided during high-temperature processing or operation of dispenser cathodes. Keywords: Dispenser cathodes, Contamination, Sulfur, Stainless steel, Hydrogen sulfide, Sulfides, Sulfates, Water, Barium sulfide.

Descriptors :   *SULFIDES, *DECOMPOSITION, *SULFUR COMPOUNDS, *HYDROGEN SULFIDE, BARIUM, CALCIUM, CATHODES, SULFUR, SURFACES, ACTIVATION, PROCESSING, DRY MATERIALS, HYDROGEN, HIGH TEMPERATURE, DISPENSERS, MOLYBDENUM COMPOUNDS, CHROMIUM COMPOUNDS, IRON COMPOUNDS, NICKEL COMPOUNDS, SILICON COMPOUNDS, CATHODES(ELECTRON TUBES), ELECTRON EMISSION, OPERATION, STAINLESS STEEL, SULFATES, THERMODYNAMICS, CONTAMINANTS, CONTAMINANTS

Subject Categories : Inorganic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE