Ignition of anthracite by a laser pulse

The ignition of tableted samples (ρ = 1 g/cm3) of microparticles (d ≤ 63 microns) of anthracite by laser pulses (532 nm, 10 ns, (0.15–0.5) 109 W/cm2) was studied. When the critical energy density Hcr(1) ≈ 0.15 J/cm2 is exceeded, an optical breakdown of the sample surface occurs during the laser pulse and the formation of a plasma flare with a lifetime of ≥ 5 microseconds. The amplitude of the plasma glow, depending on the energy density of the laser pulses, is described in the framework of the optical breakdown model. The presence of the following atoms and molecules in plasma was identified by the luminescence spectra: C, C+, Ca+, Fe+, Fe, CN, C2, CO. At a density of H > Hcr(2), in anthracite samples, as in hard coals, thermochemical reactions are initiated in the volume of microparticles, the release and ignition of volatile substances and №n-volatile residue in a submillisecond time interval.