New Investigations of the Mechanisms of Lightning Strike to Radomes Part I : Experimental Study in High Voltage Laboratory

Abstract

The main purpose of the experiments described here is the analysis of the mechanisms of radome protection with lightning diverters of various types and sizes. A high voltage arrangement and associated diagnostics have been implemented to perform a quantitative study of the inception and propagation mechanisms of the corona and leader discharges that precede the final breakdown. It is shown that ambient humidity plays a significant role on the discharge process and that the nature of the discharge initiated from the strip is very different depending on the strip type. Segmented strips are more likely to allow energetic discharges to propagate from an internal antenna leading to radome puncture.

Study of Effects of Lightning Strikes to an Aircraft

“…It can be observed that the electric field at the radome base decreases by 50 % if 6 solid diverter strips of 0.4m length were installed on the radome surface. This is in good agreement with the measurements (Ulmann et al, 2001). a) side view b) view from top …”

“…In high ambient humidity conditions (>60%), the radome becomes moderately conductive because of humidity absorption at its surface (Ulmann et al, 2001;Delannoy et al, 2001). Although this decreases the internal field due to shielding effect, it also reduces the efficiency of the strips.…”

“…9). For this radome, electric field measurement results at its base were reported (Ulmann et al, 2001;Delannoy et al, 2001), which allows comparison of simulations with experimental data. Here, solid strips were considered as inclined isolated rods in a uniform external electric field, since the analytical expressions for the electric field distribution exist in this case.…”

New Investigations of the Mechanisms of Lightning Strokes to Radomes Part II : Modeling of the Protection Efficiency

“…At low ambient air humidity, the radome is perfectly insulating. Therefore, the field measured at the internal electrode [1] is lowered only by the presence of the diverter strips through three different effects that appear in sequence during the voltage rise:…”

“…The mechanisms of inception and propagation of corona and leader discharges around a radome, equipped with 4 diverter strips and an internal electrode representing the radar, are described in a companion paper [1]. The radome is located in a plane to plane gap submitted to an impulse voltage.…”