Ignition of Anthracite Microparticles by Continuous Wave Laser Radiation with Wavelengths of 450 and 808 nm

The energy and spectral kinetic characteristics of the ignition of anthracite microparticle powders with a bulk density of 0.5 g/cm³ were measured when exposed to continuous wave laser radiation at wavelengths λ = 450 and 808 nm with an exposure time of 1 s. The ignition delay times were measured depending on the radiation power density, and the critical values of the ignition energy density of anthracite samples were determined. The energy costs for igniting anthracite for radiation with λ = 450 nm are lower than those for radiation with λ = 808 nm. In the emission spectra of anthracite resulting from the absorption of laser radiation, a glow associated with the release and ignition of volatile substances (CO flame and glow of excited CO, C₂, and H₂O molecules) and a thermal glow associated mainly with the heated surface of the samples and the emission of hot carbon particles were observed.