Objectives To enhance the effectiveness of button-type metal diverter strips in ship-radome lightning protection, their ionization characteristics should be investigated under conditions simulating the vicinity of approaching lightning leaders.

Methods  We present the experimental results of DC breakdown voltage for button-type diverter strips with various button spacings, button shapes, and diverter strip lengths, for comparing their ionization capabilities. Accordingly, we performed electrostatic field distribution calculations for the corresponding strips.

Results  Our experimental results show that, with increasing diverter strip length, the breakdown voltage of diverter strip exhibits saturation. For a fixed diverter strip length, a larger spacing between metal buttons results in higher breakdown voltage. Moreover, the breakdown voltage of elliptical-button diverter strip is the lowest, roughly 77% of that of circular-button diverter strips. Furthermore, the breakdown voltage of rectangular-button diverter strips is about 86% of that of circular-button diverter strips. Our electrostatic field calculations suggest that the electric field intensity distribution of button-type diverter strip is relatively high at both ends and low in the middle, and that the smaller the spacing between buttons, the higher electric field strength at the gap near both ends. Compared with the circular-button and rectangular-button diverter strips, the electric field strength at both ends of the elliptical-button diverter strip is the highest. The electric field strength between the two ends of the diverter strip gap decreases nonlinearly with the increasing diverter strip length, thus explaining the variation in breakdown voltage observed in the experiments due to differences in button shapes and specifications.

Conclusions  Results provide a basis for the optimization of button-type metal shunt strips, thereby enhancing the lightning protection performance of radomes.