The Atomphysical Interpretation of Lichtenberg Figures and Their Application to the Study of Gas Discharge Phenomena
The extremely finely detailed drawing in Lichtenberg figures offers an unusually clear record of the early stages of discharge phenomena. The interpretation of these records in terms of electronic ionization, space charge, plasma formation, and neutralization of charges is presented in this paper. After giving a short summary of our present knowledge about gas breakdown, the ``normal'' history of a Lichtenberg discharge is established by a study in nitrogen between five millimeters of mercury and thirty atmospheres of pressure. It progresses in three stages—the primary figure, spark development, and the discharge of negative surface charges. (The ``back figure.'') Admixture of carbon tetrachloride and experiments in ``Freon'' up to six atmospheres show the decisive influence of electro-negative components on the development of the phenomena, and reveal the reasons why these new gases are so effective in suppressing corona discharges. Deviations from Paschen's law, recently observed by several workers, can be interpreted in terms of the photographic evidence gained.