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We study the linear stability of an arbitrary number N of cylindrical concentric shells undergoing a radial implosion or explosion.We derive the evolution equation for the perturbation i η at interface i; it is coupled to the two adjacent interfaces via η i ±1 . For N=2, where there is only one interface, we verify Bell's conjecture as to the form of the evolution equation for arbitrary ρ 1 and ρ 2 , the fluid densities on either side of the interface. We obtain several analytic solutions for the N=2 and 3 cases.We discuss freeze-out, a phenomenon that can occur in all three geometries (planar, cylindrical, or spherical), and "critical modes" that are stable for any implosion or explosion history and occur only in cylindrical or spherical geometries. We present numerical simulations of possible gelatin-ring experiments illustrating perturbation feedthrough from one interface to another. We also develop a simple model for the evolution of turbulent mix in cylindrical geometry and define a geometrical factor G as the ratio h cylindrical / h planar between cylindrical and planar mixing layers. We find that G is a decreasing function of o R R / , implying that in our model h cylindrical evolves faster (slower) than h planar during an implosion (explosion).

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We present experimental results supporting physics-based ejecta model development, where our main assumption is that ejecta form as a special limiting case of a Richtmyer–Meshkov (RM) instability at a metal–vacuum interface. From this assumption, we test established theory of unstable spike and bubble growth rates, rates that link to the wavelength and amplitudes of surface perturbations. We evaluate the rate theory through novel application of modern laser Doppler velocimetry (LDV) techniques, where we coincidentally measure bubble and spike velocities from explosively shocked solid and liquid metals with a single LDV probe. We also explore the relationship of ejecta formation from a solid material to the plastic flow stress it experiences at high-strain rates ($1{0}^{7} ~{\mathrm{s} }^{\ensuremath{-} 1} $) and high strains (700 %) as the fundamental link to the onset of ejecta formation. Our experimental observations allow us to approximate the strength of Cu at high strains and strain rates, revealing a unique diagnostic method for use at these extreme conditions.

Ohio 44106We suggest that the reactions pp~*W yX and pp -*W yX are good candidates for measuring the magnetic moment parameter K in /% = (e/2M w ) (1 +K) . The angular distribution of the W bosons in pp-* W yX is particularly sensitive to this parameter. For the gaugetheory value of K -1, we have found a peculiar zero in d

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We present explicit analytic expressions for the evolution of the bubble amplitude in Rayleigh-Taylor ͑RT͒ and Richtmyer-Meshkov RM instabilities. These expressions are valid from the linear to the nonlinear regime and for arbitrary Atwood number A. Our method is to convert from the linear to the nonlinear solution at a specific value * of the amplitude for which explicit analytic expressions have been given previously for A ϭ1 ͓K. O. Mikaelian, Phys. Rev. Lett. 80, 508 ͑1998͔͒. By analyzing a recent extension of Layzer's theory to arbitrary A ͓V. N. Goncharov, Phys. Rev. Lett. 88, 134502 ͑2002͔͒, we find a simple transformation that generalizes our solutions to arbitrary A. We compare this model with another explicit model attributed to Fermi and with numerical simulations. Fermi's model agrees with numerical simulations for the RT case but its extension to the RM case disagrees with simulations. The model proposed here agrees with hydrocode calculations for both RT and RM instabilities.