Experimental Study on Discharge Behavior of Combined Air Gap with Segmented floating Conductors

Abstract

Radomes located at the protruding parts of aircrafts are susceptible to direct lightning strikes. Especially the metamaterial radomes, which have a high failure rate of lightning protection due to the large number of periodically arranged metal microstructures inside. The upward discharge initiated from the metamaterial radome is a key physical process during the lightning attachment. However, the existence of metal microstructures makes the discharge gap a combined gap consisting of a long air gap and some floating conductors. In order to simulate the upward discharge behavior initiated from the metamaterial radome, in this paper, an experimental study on the discharge behavior of combined air gap with segmented floating conductors under switching impulse voltage is carried out. A segmented floating conductors-plane gap is designed and an observation platform is set up to synchronously record the voltage waveforms, the discharge currents, the discharge processes and the whole discharge channels. The research shows that the discharge process of the combined air gap with segmented floating conductors include the first corona injection, progressive breakdown of the gaps along the segmented conductors, leader channel along the segmented floating conductors as well as the following discontinuous leader development. At the beginning of the discharge, the discharge channel along segmented floating conductors is a leader-like channel, and it becomes a section of the leader channel in the subsequent discharge phase. Different from the discharge process in long air gap, the segmented floating conductors have a certain constraint on the initial discharge path. But as the distance between adjacent metal conductors increases, the randomness of the initial discharge path increases. The research results can provide data support for the research on lightning attachment process and mechanism of the metamaterial radomes.