Absorption of electromagnetic radiation in an advanced propulsion system

Abstract

The concept of beamed energy propulsion is studied in detail with emphasis on the strong interaction between a laser beam and a flowing gas. The problem is modeled in a one-dimensional sense using a * 'pseudoconvergent optical beam. The beam convergence enables the mass flow to be dictated by the nozzle throat rather than by the eigensolution for the laser supported plasma. The results show that the mass flux and thrust achieved through a fixed nozzle is nearly independent of the incoming intensity, a result which is in sharp contrast to calculations based on laser supported plasma eigenvalues. The range of laser intensities which can be used with a given nozzle is also limited, but the results indicate that the location of the plasma inside the absorber can be controlled by the nozzle and incident beam. The effect of laser wavelength on the laser supported plasma wave is also shown and the effects of frozen flow on the propulsive performance are estimated. Nomenclature