CAREER: Study of a Femtosecond-Initiated Continuous Optical Discharge for Combustion Applications

Emerging propulsion and energy systems that use clean burning fuels require efficient ignition and stable combustion. This project addresses limitations of traditional combustion techniques by pioneering a laser-driven plasma method for active combustion control called continuous optical discharge. This technique is aimed at enhancing ignition, flame stability, and emissions control in engines. The project will develop a completely non-intrusive, tunable plasma-based combustion control method that can operate across a wide range of engine conditions. Results from the project will advance clean energy solutions in aerospace and industrial applications. Additionally, the project will support educational activities that engage K-12 students in propulsion-related topics through interactive, simulation-based learning tools. These activities will foster interest in science, technology, engineering, and mathematics among students and help expand a future science and engineering workforce. This project will determine the conditions that are required to achieve an optical plasma discharge with a high degree of selectivity, which can be optimized for various combustion applications. The project will employ an initial femtosecond laser pulse to create a cold, non-equilibrium plasma filament. Following this, an overlapped continuous-wave laser will act as a “dimmer switch”: by controlling the amount of energy deposited into the filament, the plasma will be gradually heated until a fully ionized thermal plasma is generated. This will enable control over the thermal and kinetics mechanisms influencing the plasma-flame coupling. Research objectives include: i) experimental studies of plasma properties in a high-pressure cell using advanced laser-based diagnostics, such as laser scattering and optical emission spectroscopy; ii) development of a numerical model of the continuous optical discharge to elucidate the chemical kinetic pathways enhancing combustion; and iii) demonstrating the continuous optical discharge feasibility for combustion improvements in high-pressure environments. This approach is expected to yield significant advances in the current understanding of both combustion control and plasma generation at optical frequencies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.