Studies of the cylindrically converging Richtmyer-Meshkov instability using pulsed-power produced shockwaves*

We present initial measurements of cylindrically convergent Richtmyer-Meshkov instability (RMI) driven by fast electrical explosion of a cylindrical wire array embedded in a dielectric. The explosion launched a shock wave travelling at > 2 km/s into the surrounding material, driving the implosion of an air cavity enclosed by a sinusoidal interface of Atwood number A = -1, wavelength λ = 20 mm and initial amplitude a₀ = 0.25mm. Experiments in different dielectrics spanned a parameter space from an ideal hydrodynamic regime to one where material strength becomes a significant factor.

This investigation was conducted using a portable pulsed-power generator (120 kA in 600 ns) at the European Synchrotron, enabling access to multi-MHz X-ray radiography; with spatial resolution of 32 μm and interframe time of 176 ns. Previous experiments performed on this platform demonstrated its advantages via study of planar RMI [1]. 

Extension of the presented work will explore additional phenomena such as Bell-Plesset effects, suppression of the RMI by material strength in convergent geometries [2], or more complex material dynamics in computationally optimized  geometries [3].

[1] J. Strucka, PoF, 35(4):044108

[2] G. Dimonte, PRE, 69:056305

[3] D. M. Sterbentz, PoF, 34(8):082109