Shear interferometric measurement of electron density in a laser-ablated GAP-coated nano-aluminium plasma plume

Understanding the plasma dynamics of advanced energetic materials is crucial for their application. For the first time, this study presents a quantitative, two-dimensional mapping of the electron density distribution in plasma plumes generated by the laser ablation of glycidyl azide polymer (GAP)-coated nano-aluminum (Al@GAP). We employed a time-resolved, full-field polarizing shear interferometer to capture the plume’s spatiotemporal evolution. By analyzing interference fringe shifts with an Abel inversion, we systematically investigated the effects of laser fluence (5.8–24.6 J/cm2) and ambient pressure (10–75 kPa). The results reveal peak electron densities on the order of 1016 cm−3 and complex plume structures governed by interactions with the ambient gas. Notably, we observed a non-monotonic relationship between laser fluence and central electron density, with higher fluences promoting radial expansion and reducing central density. These findings provide unprecedented quantitative insight into the energy release mechanisms and fluid dynamics of Al@GAP plasmas, offering a critical dataset for optimizing high-performance propellants, laser propulsion systems, and other energy-release applications.