Laser Ignition of Solid Propellants Using Energetic nAl-PVDF Optical Sensitizers

Abstract

Laser ignition could provide better control of the ignition process and improve safety. However, sustained ignition is often difficult to achieve in solid propellants due to a lack of optical absorbtivity at convenient wavelengths. Opacifiers can help with this, but more materials are available that combine absorptivity with more optimal reactivity for ignition. In this work, ammonium perchlorate (AP)/hydroxyl-terminated polybutadiene (HTPB) composite propellants are optically sensitized by adding energetic nAl/PVDF particles, which led to sustained ignition with relatively low laser energy levels (< 5 J/cm2). This propellant was compared to a neat AP/HTPB propellant, a propellant with carbon black additive, and a propellant with nano-aluminum (nAl) additive. Only the nAl/PVDF propellant exhibited sustained ignition. The nAl/PVDF particles were characterized using optical imaging and ranged from 600 to 1000 μm. The ignition delays of the propellant with nAl/PVDF additives ranged from 1.8 to 4.5 ms, depending on the energy density of the laser. These optically sensitive additives offer improved ignition for solid propellants and exhibit sustained burning over a wide range of laser energies.