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TECHNIQUES FOR FABRICATION SCANNABLE COLD CATHODES
ARMY ELECTRONICS COMMAND FORT MONMOUTH NJ
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Experiments were made with Field Emission Type of Cathodes. The formation of asperities was demonstrated on plain molybdenum layers using the aluminum alloying technique. It was found that too little aluminum fails to produce asperities whereas an excess of aluminum results in irregular corrosion of the molybdenum surface. Experiments in which asperities were grown on molybdenum areas confined by insulating layers showed that the presence of these layers may affect the formation of asperities. Alumina inhibited the growth of asperities in the immediate vicinity of the alumina layer. Silicon monoxide did not appear to adversely influence the formation of asperities. Experiments were made with Transverse-Field Type of Cathodes. The preparation of transverse- field type of cathodes was explored using various cathode configurations, materials and techniques. Vacuum deposition methods were found to be superior to spray-coating techniques in the preparation of the cathodes. Cathode configurations in which the gap between the two conductors was controlled by an insulating film sandwiched between the conductors appeared to be the most promising approach toward the fabrication of a useful cathode. Difficulties were experienced with such structures from short circuits between the conducting layers. It was concluded that these failures were not necessarily caused by defects of the insulating layer, but that, in some instances, the two conductors may have come in direct contact inside the structure due to a mismatch of the thicknesses of the insulating layer and the base electrode. The feasibility of preparing a BaO film such as to carry an electron current across the gap of a cathode structure was demonstrated. Author
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