The effect of laser induced breakdown in hot atomic oxygeng gas

The threshold of laser induced breakdown in high temperature atomic oxygen gas is obtained by solving quantum Boltzmann equation for electrons numerically. This threshold is much more smaller than that in low temperature molecular gas. The reason is that in the high temperature gas, the distribution of energy level and the degree of freedom is much more different from that in molecular gas. The vibrational excitation of molecule in molecular gas dose not exist in atomic gas, which reduces the energy loss of electrons and increases ionization rate.