  The compression of a cylindrical gas bubble by an imploding molten lead (Pb)
shell may be accompanied by the development of the Richtmyer-Meshkov (RM)
instability at the liquid-gas interface due to the initial imperfection of the
interface. A converging pressure wave impinging upon the interface causes a
shell of liquid to detach and continue to travel inwards, compressing the gas
bubble. The efficiency of compression and collapse evolution can be affected by
development of the RM instability. Investigations have been performed in the
regime of extreme Atwood number $A=-1$ with the additional complexity of
modeling liquid cavitation in the working fluid. Simulations have been carried
out using the open source CFD software OpenFOAM on a set of parameters relevant
to the prototype compression system under development at General Fusion Inc.
for use as a Magnetized Target Fusion (MTF) driver.
  After validating the numerical setup in planar geometry, simulations have
been carried out in 2D cylindrical geometry for both initially smooth and
perturbed interfaces. Where possible, results have been validated against
existing theoretical models and very good agreement has been found. While our
main focus is on the effects of initial perturbation amplitude and azimuthal
mode number, we also address differences between this problem and those usually
considered, such as RM instability at an interface between two gases with a
moderate density ratio. One important difference is the formation of narrow
molten lead jets rapidly propagating inwards during the final stages of the
collapse. Jet behaviour has been observed for a range of azimuthal mode numbers
and perturbation amplitudes.
