ROCKET-TRIGGERED LIGHTNING STUDIES FOR THE PROTECTION OF CRITICAL ASSETS

Lightning protection systems (LPS's) for explosives handling and stora ge facilities have long been designed similarly to those used for more conventional facilities, but their overall effectiveness in controlli ng interior electromagnetic (EM) environments has still not been rigor ously assessed. Frequent lightning-caused failures of a security syste m installed in earth-covered explosives storage structures prompted th e U.S. Army and Sandia National Laboratories to conduct a program to d etermine quantitatively the EM environments inside an explosives stora ge structure that is struck by lightning. These environments were meas ured directly during rocket-triggered lightning (RTL) tests in the sum mer of 1991 and were computed using linear finite-difference, time-dom ain (FDTD) EM solvers. The experimental and computational results were first compared in order to validate the code and were then used to co nstruct bounds for interior environments corresponding to severe incid ent lightning flashes. The code results were also used to develop simp le circuit models for the EM field behavior-a process that resulted in a very simple and somewhat surprising physical interpretation of the structure's response that has significant practical and economic impli cations for design, construction, and maintenance of such facilities.