Stability and evolution of wave packets in strongly coupled degenerate plasmas

Abstract

We study the nonlinear propagation of electrostatic wave packets in a collisional plasma composed of strongly coupled ions and relativistically degenerate electrons. The equilibrium of ions is maintained by an effective temperature associated with their strong coupling, whereas that of electrons is provided by the relativistic degeneracy pressure. Using a multiple scale technique, a (3+1)-dimensional coupled set of nonlinear Schrödinger-like equations with nonlocal nonlinearity is derived from a generalized viscoelastic hydrodynamic model. These coupled equations, which govern the dynamics of wave packets, are used to study the oblique modulational instability of a Stoke's wave train to a small plane wave perturbation. We show that the wave packets, though stable to the parallel modulation, becomes unstable against oblique modulations. In contrast to the long-wavelength carrier modes, the wave packets with short-wavelengths are shown to be stable in the weakly relativistic case, whereas they can be stable or unstable in the ultra-relativistic limit. Numerical simulation of the coupled equations reveals that a steady state solution of the wave amplitude exists together with the formation of a localized structure in (2+1) dimensions. However, in the (3+1)-dimensional evolution, a Gaussian wave beam self-focuses after interaction and blows up in a finite time. The latter is, however, arrested when the dispersion predominates over the nonlinearities. This occurs when the Coulomb coupling strength is higher or a choice of obliqueness of modulation, or a wavelength of excitation is different. Possible application of our results to the interior as well as in an outer mantle of white dwarfs are discussed.

18 pages, 7 figures; To appear in Phys. Rev. E (2012); The manuscript has been revised with few discussions and citation of some relevant references

References in corpus (4)

• Colloquium: Nonlinear collective interactions in quantum plasmas with degenerate electron fluids
• Stability of two-dimensional spatial solitons in nonlocal nonlinear media
• Rare White dwarf stars with carbon atmospheres
• Modulational instability and nonlinear evolution of two-dimensional electrostatic wave packets in ultra-relativistic degenerate dense plasmas

Cited by in corpus (4)

• Linear and nonlinear ion-acoustic waves in non-relativistic quantum plasmas with arbitrary degeneracy
• Characteristics of solitary waves in a relativistic degenerate ion beam driven magneto plasma
• Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma
• Transverse instability of electron-acoustic solitons in a relativistic degenerate astrophysical magnetoplasma