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In this paper, small but finite amplitude electrostatic solitary waves in a relativistic degenerate magnetoplasma, consisting of relativistically degenerate electrons and non-degenerate cold ions, are investigated. The Zakharov-Kuznetsov equation is derived employing the reductive perturbation technique and its solitary wave solution is analyzed. It is shown that only compressive electrostatic solitary structures can propagate in such a degenerate plasma system. The effects of plasma number density, ion cyclotron frequency, and direction cosines on the profiles of ion acoustic solitary waves are investigated and discussed at length. The relevance of the present investigation vis-a-vis pulsating white dwarfs is also pointed out. [ABSTRACT FROM AUTHOR]

The ever increasing performance of supercomputers is now enabling kinetic simulations of extreme astrophysical and laser produced plasmas. Three-dimensional particle-in-cell (PIC) simulations of relativistic shocks have revealed highly filamented spatial structures and their ability to accelerate particles to ultrarelativistic speeds. However, these PIC simulations have not yet revealed mechanisms that could produce particles with tera-electron volt energies and beyond. In this work, PIC simulations in one dimension (1D) of the foreshock region of an internal shock in a gamma ray burst are performed to address this issue. The large spatiotemporal range accessible to a 1D simulation enables the self-consistent evolution of proton phase space structures that can accelerate particles to giga-electron volt energies in the jet frame of reference, and to tens of tera-electron volt in the Earth’s frame of reference. One potential source of ultrahigh energy cosmic rays may thus be the thermalization of relativistically moving plasma. [ABSTRACT FROM AUTHOR]

The free energy associated with shear in the equilibrium parallel electron velocity is shown to be responsible for the excitation of low-frequency electromagnetic waves in collisionless magnetoplasma. New dispersion relations are derived by using the hydrodynamic equations for the electron fluid, the magnetic-field-aligned (parallel) drift of which varies in one of the perpendicular directions, and by using a kinetic ion model, together with Ampère’s law and Poisson’s equation. The dispersion relations are analyzed both analytically and numerically for a set of parameters representative of a laboratory experiment. New filamentary instabilities are predicted. [ABSTRACT FROM AUTHOR]

The interaction between relativistic ion beams, electrostatic waves and particles in plasmas is studied numerically. This beam-particle interaction is important for the acceleration of electrons above the threshold, where they can perform Fermi acceleration across shocks perpendicular to the magnetic field direction. The electrons form Bernstein-Greene-Kruskal (BGK) modes, which are unstable due to a sideband instability. This process heats the electrons to relativistic temperatures and the electrons finally attain a flat-top momentum distribution with exponentially decreasing tails of the momentum distribution function. A scaling law, depending on the ion beam speed, is found for the electron distribution function. Furthermore, in the fully nonlinear phase, ion phase space vortices, or proton BGK modes are formed in the beam, which continue to interact with the electrons after the electron BGK modes have collapsed. [ABSTRACT FROM AUTHOR]

Exact nonlinear equations for magnetosonic shocklets in a uniform hot magnetoplasma are derived by using the nonlinear magnetohydrodynamic equations. Analytic, as well as numerical, solutions of the nonlinear equations are presented. Shocklike structures of the ion fluid velocity and magnetic field (or the plasma density) perturbations are obtained. The results may have relevance to the understanding of fast magnetosonic shocklets that have been recently observed by onboard instruments of the Cluster spacecraft at the Earth's bow shock. [ABSTRACT FROM AUTHOR]

The article presents a response from the author of the article "On the Theory of Plasma-Wall Transition Layers." The authors explained that a semibounded plasma is considered in their article, where the length of the discharge is infinite, which is in contrast to the Tonks-Langmuir model, which involves a finite size referred by the critic.