Laser–matter interactions: Inhomogeneous Richtmyer–Meshkov and Rayleigh–Taylor instabilities

Abstract

In this experimental study, the ablative Richtmyer–Meshkov (RM) and the Rayleigh–Taylor (RT) instabilities were generated by the laser pulse of Gaussian-like power profile. The initial multi-modal perturbation, the inhomogeneous momentum transfer and different Atwood numbers generate different shapes of spikes and bubbles in the central region (CR) and the near-central region (NCR) of the spot. A one-dimensional Gaussian-like power profile causes the formation of the wavy-like rows of aperiodic spikes. The periodic spike segments inside the rows appear due to locally coherent flow. In the NCR, the mushroom-shape spikes tend to the organization on the isotropic square and the anisotropic rhombic lattices. The increase of the lattice periods two, three, or four times indicates formation of superstructures. The growth of sharp asymmetric RM/RT spikes in the CR is fast, uncorrelated and linear, while the growth of the symmetric mushroom-shape ones in the NCR is slow, correlated, and nonlinear.

On the Rayleigh-Taylor unstable dynamics of three-dimensional interfacial coherent structures with time-dependent acceleration

“…The Atwood bubble has a quasi-invariance property suggesting that nonlinear coherent RM dynamics is set by the interplay of two macroscopic length-scales -the wavelength and the amplitude. Our theory agrees with existing observations, and elaborates new benchmarks for observations 6,[8][9][10][11][12][13][14][20][21][22][23] .…”

Inertial dynamics of an interface with interfacial mass flux: Stability and flow fields’ structure, inertial stabilization mechanism, degeneracy of Landau’s solution, effect of energy fluctuations, and chemistry-induced instabilities

“…According to our results, for given values of the fluid densities Table 6 [24][25][26][27][28][29][30][31][32][33][34][35]. By accurately diagnosing the interface dynamics, including the growth of the interface perturbations and the interface velocity, one can confidently identify the new fluid instability in experiments with strong accelerations [5][6][7][8][9].…”

“…Non-equilibrium transport, interfaces and mixing are omnipresent in nature and technology at astrophysical and at molecular scales, and in high and low energy density regimes [1]. Fluid instabilities and interfacial mixing in supernovae and in inertial confinement fusion, particle-field interactions in magnetic fusion and in imploding Z-pinches, downdrafts in stellar interior and in planetary magnetoconvection, coronal mass ejections in the Solar flares and plasma instabilities in the Earth ionosphere, plasma thrusters and nano-fabrication -are examples of processes governed by non-equilibrium interfacial dynamics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The realistic environments are often characterized by sharply and rapidly changing flow fields and by small effects of dissipation and diffusion resulting in the formation of discontinuities (referred to as fronts or as interfaces) between the flow non-uniformities (phases) at macroscopic (continuous) scales [11].…”

“…The theory [21][22][23] considered inertial and accelerated interface dynamics for ideal incompressible fluids free from stabilizations caused by interactions of particles at molecular scales [14][15][16][17]. Realistic processes are usually accompanied by dissipation, diffusion, compressibility, radiation transport, stratification, and surface tension [3][4][5][6][7][8][9][10][11][12][13][14][15][39][40][41][42][43]. The influence of these effects on the interface dynamics call for systematic investigations [21].…”

“…We further find the critical and maximum values of the initial perturbation wavelengths at which the fluid instability of the conservative dynamics can be stabilized and at which its growth is the fastest. Based on the obtained results, we identify the theory benchmarks for future experiments and simulations in high energy density plasmas and outline its outcomes for application problems in nature and technology [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][39][40][41][42][43][44][45].…”