In situ nanopowder combustion visualization using laser systems with brightness amplification

Abstract

In this paper, we report on an experimental demonstration of a new technique for real-time monitoring of the air combustion of aluminum-based nanopowders and mixtures. An optical system having a brightness amplifier is used for sample-surface imaging during high-temperature combustion. The main advantage of the laser-monitor application, compared with direct high-speed imaging, is the possibility of seeing through the intense glowing of a burning sample. Furthermore, the proposed laser monitor has an increased monitoring distance compared with known systems, which is provided by a mirror-imaging scheme applied to the laser monitor. The proposed technique allows real-time monitoring of high-temperature combustion processes accompanied by intensive lighting and product scattering at a distance of up to 50 cm from the optical system. The operation of the optical system is tested using both a quietly burning aluminum nanopowder and aluminum-based explosive mixtures. The combustion of a nanoAl+µAl+µFe powder mixture and aluminized blended propellant is visualized using a laser monitor for the first time.