BEHAVIOR OF CATHODE SPOTS IN A HIGH-CURRENT ELECTRIC DISCHARGE,
FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO
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Investigation of a high-current single discharge at atmospheric pressure revealed the existence of cathode spots of two types. Spots of the first type, characterized by a high rate of motion toward fresh sections of the electrode, evidently form on all metals. If an autoelectronic mechanism of emission from a cathode is assumed, then the characteristics of their behavior can be explained by the fact that when the surface irregularities of the metal are fused and its crystalline structure is disrupted by bombardment of positive ions, electron emission within the spot decreases. Spots of the second type have low mobility and form only on metals with low values of thermophysical constants in places of local cathode boiling. Their formation is connected to the increased concentration of metallic vapor under the boiling surface making the ionizing action of the primary electrons more effective. The attachment of these spots to the vaporization centers, which follows from this, causes their low mobility.