Multimode seeded Richtmyer–Meshkov mixing in a convergent, compressible, miscible plasma system

Abstract

Richtmyer–Meshkov (RM) mixing seeded by multimode initial surface perturbations in a convergent, compressible, miscible plasma system is measured on the OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system. A strong shock (Mach 12–20), created by 50 laser beams, is used to accelerate impulsively a thin aluminum shell into a lower density foam. As the system converges, both interfaces of the aluminum are RM unstable and undergo mixing. Standard x-ray radiographic techniques are employed to survey accurately the zero-order hydrodynamics, the average radius and overall width, of the marker. LASNEX [G. B. Zimmerman et al., Comments on Plasma Physics 2, 51 (1975)] simulations are consistent with the zero-order behavior of initially smooth markers. In experiments with smooth aluminum markers, the measured marker width shortly after shock passage behaves incompressibly and thickens due to Bell–Plesset effects. At high convergence (>4), the marker begins to compress as the rebounding shock passes back through the marker. When an initial multimode perturbation is introduced to the outer surface of the marker, the measured marker width is observed to increase by 10–15 μm, and is substantially smaller than as-shot simulations using RAGE [R. M. Baltrusaitis et al., Phys. Fluids 8, 2471 (1996)] would predict.

Richtmyer–Meshkov instability for elastic–plastic solids in converging geometries

“…Although these values may not be accessible in experiments, CH foams (such as the ones used in Lanier et al, 2003) are available in this density range and their compression behavior replicates that of an ideal gas. In order to achieve the desired initial Mach number, the inverse deformation tensor in cylindrical coordinates at r R s = is…”

“…The RMI in converging geometries mostly appears in experiments aiming to achieve inertial confinement fusion (ICF) (Lindl, 1998), plasma generation (Lanier et al, 2003), and in astrophysical phenomena, such as supernova formation (Fryxell et al, 1991). This geometrical configuration represents a more complex problem owing to the acceleration of the shock and interface as they approach the axis/origin, the second shock-interface interaction (re-shock) after the transmitted shock reaches the axis, and the presence of secondary instabilities such as Rayleigh-Taylor (Yu and Livescu, 2008;Mikaelian, 2004) (interface acceleration) and KelvinHelmholtz (discontinuity in tangential velocities across the interface).…”

Nonlinear growth of the converging Richtmyer-Meshkov instability in a conventional shock tube

“…The authors postulate that this lack of saturation is due to the suppression of the growth of secondary instabilities due to the convergent effects. However, the cylindrical shell of these experiments undergoes a deceleration [37] which was discarded by the authors. This deceleration leads to a 25% relative discrepancy between the actual and the coasting trajectories.…”

Small-amplitude perturbations in the three-dimensional cylindrical Richtmyer–Meshkov instability

“…2 Examples of the occurrence of RMI in converging geometries, in particular, the cylindrical geometry, are present in experiments aiming to achieve inertial confinement fusion 3 ͑ICF͒ or in natural phenomena such as supernova collapse. 4 Although experiments on fluid mixing in cylindrical and spherical geometries have been conducted to elucidate shock convergence effects, [5][6][7] open questions remain; see Sec. V in Ref.…”