Absorption and scattering by conductive fibers: Basic theory and comparison with asymptotic results

A theory based on the variational method, along with associated computer codes, has been developed for analyzing the electromagnetic scattering and absorption from thin conductive fibers of arbitrary size, conductivity and orientation. Extensions and refinements of this theory have now been completed and programmed. A summary is given of the basic equations used in the variational computation for arbitrary fibers. The quasistatic model appropriate at long wavelengths is then derived, followed by the infinite cylinder computation which should be accurate for wavelengths short compared with cylinder length. In order that the computations may be extended into the infrared and visible regimes, it is necessary to incorporate the optical properties of the fibers. Curved fibers are considered in this report. An exact integral equation is derived for the general case, and some approximate results are then given for special fibers. Also discussed are the optimum conditions for target obscuration by a cloud of particles from a mass efficiency standpoint. Particle optimization studies are performed under varying requirements on absorption, reflection, and transparency of the particle cloud.