Tunable plasma and combustion wave dynamics in fused silica induced by combined millisecond–nanosecond laser pulses under airflow control

This paper investigates the control of plasma morphology on fused silica induced by a combined millisecond–nanosecond laser under the influence of flow fields. An innovative dynamic model has been developed to control plasma and combustion wave behavior under flow field, aiming to mitigate the impact of tangential airflow on plasma and combustion wave dynamics and propagation. The physical mechanism of plasma cooling and morphological stability, resulting from the coupling of the combined laser and airflow, is revealed by optimizing the heat source terms in the Navier–Stokes and energy equations under flow field. It suppresses unnecessary expansion and instability, making it suitable for high-precision material handling and damage control. The results indicate that under 20° and 45°, the shear force generates discontinuous pressure and velocity fields, inhibiting plasma expansion and hindering particle diffusion. Oxygen-assisted combustion at 60° increases heat, allowing more laser energy injected into the core region, reducing absorption by the outer plasma, and increasing the movement rate and expansion distance. The 90° angle confines the combustion wave to the airflow injection direction, weakening the plasma boundary structure, causing the boundary region to rupture rapidly, and inducing reverse motion. The model developed predicts the expansion distance and morphology of the combustion wave under different shear force angles, offering theoretical guidance for experiments.