Mathematical Model of Dual-Pulse Laser Ignition

A model of thermal ignition by dual-pulse laser energy addition is presented in this paper. The concept of controllable energy deposition is analyzed, assuming the first low-energy short-pulse-length laser serves to preionize a well-localized region without significant optical breakdown and the second time-delayed longer-pulse-length high-energy laser pulse illuminates that region. The delayed long pulse initiates combustion within the region designated by the short prepulse. This arrangement allows tailoring of the energy deposition, gas heating, and ignition at a specific location. The mathematical model is formulated by incorporating balanced equations for electrons, ions, neutrals, electron temperature, vibrational temperature, and the total gas energy taking into account the plasma chemistry combined with the low-temperature oxidation mechanism of methane and the GRI-Mech 3.0 mechanism. The model is used to analyze the role of different heating mechanisms and initial conditions associated with the second pulse, as well as to evaluate the initial ionization requirements for successful ignition by the dual-pulse configuration.