Experimental Observations of Laser-Driven Tin Ejecta Microjet Interactions

The study of high-velocity particle-laden flow interactions is broadly applicable to fields ranging from planetary formation [1] to cloud interactions [2]. Ejecta microjets offer a novel experimental methodology to study such interactions, as microjets consist of micron-scale particles that travel at velocities greater than several kilometers per second. Microjets are generated when a strong shock releases from a surface with a feature, such as a groove or a divot; the feature then inverts as a limiting case of the Richtmyer-Meshkov Instability and forms a propagating jet of material. Recent experiments performed at the OMEGA EP laser facility observed the interaction of two counter-propagating ejecta microjets for the first time. In this presentation, we show these time-sequences of x-ray radiography images of two interacting tin jets [3]. We observe that jets emerging from a shock pressure of 11.7 GPa pass through each other unattenuated, whereas jets emerging from a shock pressure of 116.0 GPa have five times greater densities and interact strongly, forming a cloud around the center-point of interaction. Radiation hydrodynamics simulations of particle-stream collisions capture many of the observed interaction behavior characteristics, but are unable to capture the full spread of the cloud formed.



[1] M. Lambrechts et al., A&A 627, A83 (2019).

[2] T. Matsumoto et al., The Astrophysical Journal 801, 77 (2015).

[3] A. M. Saunders et al., PRL 127, 155002 (2021).