An Analysis of Air Breakdown in Electrostatic Recording

Air breakdown between a very small stylus and dielectric layer, as is often used in electrostatic recording, has been studied both theoretically and experimentally. In the experiments, styli of 60 μm diameter were placed against the dielectric layer of various thicknesses with an air gap of 1 to 60 μm. Breakdown time lag and breakdown voltage was thereby clarified as follows: 1) The logarithm of the mean statistical time lag is proportional to the logarithm of the repetition rate of breakdown and is inversely proportional to field strength in the air gap. 2) Breakdown voltage in electrostatic recording as a function of the air gap agrees well with modified Faschen curve obtained in previous experiments using large plane parallel electrodes. These results clarify the limitation of the recording speed, the minimum recording voltage, and optimum air gap length in electrostatic recording.