Initial Construction of a General Framework for Numerical Simulation of IED Detection and Remote Activation Scenarios

Abstract : We present an initial construction of a general framework for numerical simulation of the various possible types of scenarios that could possibly occur for the detection and remote activation of improvised explosive devices (IEDs) by excitation of incident electromagnetic waves. This general framework consists of a set of component models, each of whose structure permits the output of given types of information. The primary component model of this framework, to which the outputs of all the other component models are inputs, is that of an S-matrix representation of a multilayered composite material system, where each layer of the system is characterized by an average thickness and effective electric permittivity function. The outputs of this primary component are the reflectivity and transmissivity as a function of frequency and incident angle of the incident electromagnetic wave. The other component models, whose outputs are input to the S-matrix model, are response spectra calculated using density functional theory (DFT) and related methodologies, parameterized analytic function representations of the electric permittivity as a function of frequency obtained by fitting experimentally measured spectra, and effective permittivity functions whose construction is based on effective medium theory (EMT) and roughness models. We review those physical theories establishing the foundation of the component models and a prototype simulation that considers response characteristics for THz excitation. We include an initial version of a computer program for calculation of reflectivity and transmissivity functions using the S-matrix formulation. Aspects of this specific software implementation are discussed. In addition, we describe a procedure for calculating response spectra using DFT for use as input to the S-matrix model. For this purpose we have adopted the DFT software NRLMOL.