Laser initiated combustion of CH 4 + O 2 mixtures

Abstract

A single pulse from a TEA CO 2 laser is used to photo-ignite 1 : 7 : 14 and 1 : 4 : 8 mixtures of SF 6/CH 4/O 2 at pressures from 75 Torr to 200 Torr. Ignition of a 100 Torr mixture with a short duration pulse (one-half the energy deposited in 0.25 μs) requires ≈20% less absorbed energy than with a long duration pulse (one-half the energy deposited in 0.82 μs). This result indicates some nonthermal component in the combustion initiation, i.e., the short duration pulse is more effective in producing a high population density of reactive species than the longer duration pulse.