Ignition of nanothermites by a laser diode pulse

Abstract

Experimental investigation has been carried out for laser ignition and combustion of nanothermites based on aluminum and oxides of copper, bismuth and molybdenum. Ultrasonic mixing of nanosized powders was used to produce compositions. For thermite ignition, initiating laser pulse with a maximum intensity of 770 W/cm2 was generated by a laser diode with a wavelength of 808 nm. The ignition delay times, the minimum initiation energy density, and the average burning rate at various thermite densities and mass fractions of components were determined by recording the emission of radiation of the reaction products using a multichannel pyrometer jointly with a high-speed video camera. The effect of adding carbon black on the threshold parameters of a laser pulse was also studied. Based on the obtained results, certain assumptions were put forward with regard to the mechanism of nanothermites’ ignition by laser radiation and their burning. In particular, the assumptions were made on the two-stage process of the reaction initiation and jet burning mechanism of porous nanothermites.

Keywords

• Nanothermites
• Laser ignition
• Burning rate
• Ignition delay