Effects of Voltage Increase Rate on Paschen’s Curve in Air

Paschen’s law relates the gaseous dielectric breakdown voltage to the product of gas pressure and electrode separation distance. The literature contains studies that use different voltage rise times in experiments; theoretically, this should not pose a problem: the probability of finding a seed electron to initiate a discharge between two infinitely large electrodes is assumed to be 100%. However, in real systems, this is not the case, and thus, the rate of voltage increase becomes an important factor in the process. The goal of the present work was to assess the impact of different voltage rise rates on the observed discharge voltage in air, for various electrode geometries and gas pressures. Pressure is an important factor when using an electrode arrangement giving an inhomogeneous electric field because, as it decreases, the volume in which the reduced electric field is strong enough to ensure that the ionization rate exceeds the attachment rate increases, thus also increasing the probability of the presence of a seed electron. To facilitate this experimental investigation, a customized system operating at pressures between 1 mbar and 1 bar, at room temperature, and designed to test both plane–plane and point–plane electrode configurations with a fixed distance between electrodes was developed. Results from the experimental study on deviations from Paschen’s law under different voltage rise rates across varying electrode geometries and pressures will be presented, followed by a discussion of electrostatic simulations of the experimental systems, comparing these findings with the experimental results. Finally, the results will be discussed, and some possible interpretations will be outlined.