The Striated Spark

Abstract

In 1867 Toepler' found the existence of a pulse spreading from the region around the spark immediately after it had passed. Since the density of the air in the pulse differs from that of the surrounding gas, the pulse is optically different from the rest of the field and so can be made visible by the Shadowgraph Method. Toepler's work was the first of its kind where an instantaneous view, say of the order of several millionths of a second, of the electric spark was obtained. In 1926 Dr. Zinszer', while studying the life history of the electric spark by the shadowgraph method, found that in some of the discharges under consideration the gap between the electrodes was filled with alternate light and dark laminae or striations of about a millimeter in width. In a paper by Dr. Zinszer, on the Mechanism of a Condensed Spark Discharge he discusses briefly the striations produced in some types of discharges. He considers that they might be laminal aggregations of supercharged particles which are urged away from or attracted to oppositely charged terminals without an appreciable interchange of charge. There is another theory which might be considered, and that is that the striations may be analogous to standing waves in a Kuntz tube, the gap between electrodes producing the necessary resonance column and the spark concussion producing the necessary energy.