Controlling blast waves dimensionality and Mach stem formation using laser-produced annular plasmas

We report experiments on shock wave generation and interaction using a laser‑produced annular plasma as the driving source. A 10^9 W/cm2 Nd:YAG laser pulse is focused as a ring-shaped focus on an aluminum target within an argon or nitrogen atmosphere [1]. The resulting annular plasma expands launching a 2-dimensions blast wave propagation profile whose evolution differs markedly from the spherical (3-dimensional) expansion observed for point‑focus plasmas. Schlieren imaging reveals that opposing segments of the annular shock converge at the symmetry axis, where their interaction produces a Mach stem once the collision angle exceeds the critical value set by the gas adiabatic index. The position and formation time of the stem agree with analytic predictions. Moreover, the Mach stem propagates as a planar shock, reflecting the boundary constraints imposed by the annular geometry. This approach offers a controllable platform for studying multidimensional shock dynamics relevant to astrophysical and high‑energy‑density plasmas.

This work has been supported by Fondecyt/Regular 1231286

[1] F Veloso, et al; Phys Rev E 110, 065210 (2024)