Analysis of Lightning Induced Magnetic Field Penetration Through Protective Metal Screens Using an Equivalent Magnetic Dipole Moment Representation of an Array of Elliptic Apertures

摘要

This investigation analyzed lightning induced magnetic field penetration through protective metal screens using an equivalent magnetic dipole moment representation of an array of elliptic apertures. Two metal screens with differing aperture sizes were modeled. Experiments, using lightning level currents, measured the magnetic field penetration through each screen. A comparison of model versus experimental results was performed. The effect of decreasing mesh sizes on field penetration is also presented. The analysis used linear superposition to sum the contributions from the magnetic dipole moment equivalent of each screen aperture. A computer program was developed to the number of screen model. It allows the user to specify the number of screen apertures, their dimensions, and the exterior field angle across the screen. The results indicate that the model is accurate in predicting the interior magnetic field decay rate with distance from the screen and in accounting for the increased protection provided by decreasing mesh sizes. The only model inaccuracies are the overestimates for interior magnetic field strengths. The overall results indicate that an equivalent magnetic dipole moment representation can be used to model lightning induced magnetic field penetration through protective metal screens. (Thesis)