Hypersonic Experimental Analysis of Impulse Generation in Airbreathing Laser Thermal Propulsion

Abstract

This experimental campaign focused on the analysis of the feasibility for impulse generation of a repetitively pulsed airbreathing laser lightcraft at hypersonic speeds. The future application of interest for this basic research endeavor is the laser launch of nano- and microsatellites (i.e., 1–100 kg payloads) into low Earth orbit, at low cost and on demand. These laser propulsion experiments employed a hypersonic shock tunnel, integrated with twin gigawatt pulsed Lumonics 620-TEA lasers to produce the required test conditions. Time-dependent surface pressure distributions were recorded together with schlieren movies of the flowfield structure resulting from the laser energy deposition, at nominal Mach numbers ranging from 6 to 10. The laser induced breakdown occurring off-surface and across the inlet’s midchannel was analyzed and discussed against previous theoretical and experimental results. The data indicated laser induced pressure increases of 0.7–0.9 bar with laser pulse energies of , on an off-shroud induced breakdown condition and a freestream Mach number of six. The results of this research corroborate the feasibility of laser powered airbreathing flight with infinite specific impulse ().