Theoretical simulation study of laser-induced plasma bombardment on bacteria

With the rapid advancement of laser decontamination technology and growing awareness of microbial hazards, it becomes crucial to employ theoretical model to simulate and evaluate decontamination processes by laser-induced plasma. This study employs a two-dimensional axisymmetric fluid dynamics model to simulate the power density of plasma bombardment on bacteria and access its decontamination effects. The model considers the transport processes of vapor plasma and background gas molecules. Based on the destructive impact of high-speed moving particles in the plasma on bacteria, we investigate the bombardment power density under various conditions, including different laser spot sizes, wavelengths, plate’s tilt angles, and plate-target spacing. The results reveal that the bombardment power density increases with a decrease in laser spot size and wavelength. For instance, when the plate is parallel to the target surface with a 1 mm spacing, the bombardment power density triples as the laser spot size decreases from 0.8 mm to 0.5 mm and quadruples as the wavelength decreases from 1064 nm to 266 nm. Notably, when the plate is parallel to the target with a relatively close spacing of 0.5 mm, the bombardment power density at 0° inclination increases sevenfold compared to 45°. This simulation study is essential for optimizing optical parameters and designing component layouts in decontamination devices using laser-induced plasma. The reduction of laser spot size, wavelength, plate-target spacing and aligning the plate parallel to the target, collectively contribute to achieving precise and effective decontamination.