Laser for determining the ignition conditions of a pyrotechnic mixture

The characterization of an explosive, subject to thermal stimulus, by a threshold ignition energy and a threshold ignition power was studied using a CO2 laser to heat a pyrotechnic mixture of magnesium and sodium nitrate at various power levels and various pulse widths. At short pulses the sensitivity can be characterized by a threshold ignition energy density and for long pulses by a threshold ignition flux. For pulse widths between the two extremes the ignition energy density is a function of the square root of the pulse width. The experimental results are validated by theoretically solving the heat flow equation. The method allows the ignition temperature, the absorption depth, the activation energy, and the frequency factor to be calculated.