Study of polymethyl methacrylate ignition and extinction on exposure to a high-power laser pulse

Experimental results of polymethyl methacrylate ignition and extinction on exposure to laser radiation with power density $q$ = 200–1000 W/cm$^2$ are presented. For $q>$ 220 W/cm$^2$, gasphase ignition is shown to occur in the center of the circular-vortex leading edge far from the surface of a sample. For $q\le$ 220 W/cm$^2$, ignition occurs simultaneously on two sites above the surface. The action of laser radiation with $q>$ 220 W/cm$^2$ on polymethyl methacrylate after its gas-phase ignition at room temperature and atmospheric pressure does not ensure a steady combustion regime – instead, extinction is observed.