On Waveguides Critical Corona Breakdown Thresholds Dependence on the Collision Frequency between Electrons and Air

The collision frequencies between electrons and air molecules are important parameters when analyzing electrical breakdown. Different values for the collision frequency in atmospheric air have been reported in academic literature; the current analysis method for breakdown in waveguides and filters considers an electric field-independent term. However, some authors have remarked the importance of an electric field dependence of the collision frequency. In this paper, the collision frequency of electrons, accelerated by the presence of an electric field, against air molecules is obtained. The collision frequency is calculated from experimental data, for breakdown voltages at dc in positive polarity in a wide atmospheric pressure range using a plane-plane plates configuration. As waveguide filters are currently designed with a 3-dB tolerance below the electrical breakdown thresholds, this paper analyses the current methods for these breakdown threshold calculations, and proposes a novel correction factor for the collision frequency in order to approximate the analytic calculations to experimental results.