Photographic Action of high-Voltage Electric Discharge

Photographic action of high-voltage electric discharge was studied applying direct current voltage of about 4000 to 9000 V with a configuration of two electrodes and a film in between. Photographic records of discharge for both positive and negative signs were obtained, and their densities as well as stretch or diameter of the developed image were measured under various exposure conditions・ Positive discharge led to formation of Lichtenberg\u27s figure, and in this case, stretch of image increased proportionally with an increase of the applied voltage. Negative discharge formed simply circular images, and their densities or diameters varied with complexity according to sensitive materials, applied voltages, electrode distances and exposure time. It is noticeable as an unusual behaviour that a resin coated photographic paper showed higher sensitivity towards negative discharge than a panchromatic or a orthochromatic film