P. K. Shukla

A survey of dusty plasma physics

Two omnipresent ingredients of the Universe are plasmas and charged dust. The interplay between these two has opened up a new and fascinating research area, that of dusty plasmas, which are ubiquitous in different parts of our solar system, namely planetary rings, circumsolar dust rings, the interplanetary medium, cometary comae and tails, as well as in interstellar molecular clouds, etc. Dusty plasmas also occur in noctilucent clouds in the arctic troposphere and mesosphere, cloud-to-ground lightening in thunderstorms containing smoke-contaminated air over the United States, in the flame of a humble candle, as well as in microelectronic processing devices, in low-temperature laboratory discharges, and in tokamaks. Dusty plasma physics has appeared as one of the most rapidly growing fields of science, besides the field of the Bose–Einstein condensate, as demonstrated by the number of published papers in scientific journals and conference proceedings. In fact, it is a truly interdisciplinary science becaus...

Linear and nonlinear ion-acoustic waves in an unmagnetized electron-positron-ion quantum plasma

The linear and nonlinear properties of the ion-acoustic waves (IAWs) are investigated by using the quantum hydrodynamic equations together with the Poisson equation in a three-component quantum electron-positron-ion plasma. For this purpose, a linear dispersion relation, a Korteweg-de Vries equation and an energy equation containing quantum corrections are derived. Computational investigations have been performed to examine the quantum mechanical effects on the linear and nonlinear waves. It is found that both the linear and nonlinear properties of the IAWs are significantly affected by the inclusion of the quantum corrections. The relevance of the present investigation to dense white dwarfs (where the electron-positron annihilation can be unimportant) is discussed.

Solitary waves in an ultrarelativistic degenerate dense plasma

Solitary waves in an ultrarelativistic degenerate dense plasma have been investigated by the reductive perturbation method. The modified Korteweg–de Vries equation has been derived and its numerical solutions have been analyzed to identify the basic features of spherical electrostatic solitary structures that may form in such a degenerate dense plasma. The implications of our results in compact astrophysical objects, particularly in white dwarfs, have been briefly discussed.

Modulated electrostatic modes in pair plasmas: Modulational stability profile and envelope excitations

A pair plasma consisting of two types of ions, possessing equal masses and opposite charges, is considered. The nonlinear propagation of modulated electrostatic wave packets is studied by employing a two-fluid plasma model. Considering propagation parallel to the external magnetic field, two distinct electrostatic modes are obtained, namely a quasiacoustic lower moddfe and a Langmuir-like, as optic-type upper one, in agreement with experimental observations and theoretical predictions. Considering small yet weakly nonlinear deviations from equilibrium, and adopting a multiple-scale technique, the basic set of model equations is reduced to a nonlinear Schrodinger equation for the slowly varying electric field perturbation amplitude. The analysis reveals that the lower (acoustic) mode is stable and may propagate in the form of a dark-type envelope soliton (a void) modulating a carrier wave packet, while the upper linear mode is intrinsically unstable, and may favor the formation of bright-type envelope soli...

Generation of localized density perturbations by shear Alfvén waves

It is shown that the ponderomotive force of finite amplitude shear (or kinetic) Alfven waves can generate magnetic field-aligned quasistationary density humps as well as dips. The results can have relevance to the shear Alfven wave induced localized density perturbations that have been recently found in the Large Plasma Device at the University of California, Los Angeles, as well as to those observed by spacecrafts in the Earth’s auroral and magnetospheric plasmas.

Plasma density cavitation due to inertial Alfvén wave heating

It is found that the differential Joule heating of the electrons in the inertial Alfven wave fields can be responsible for the fine scale density cavitations that are observed by the FREJA and FAST (Fast Auroral SnapshoT) spacecrafts in the Earth’s auroral plasma.

Shock waves in charge-varying dusty plasmas and the effect of electromagnetic radiation

Nonlinear electrostatic wave structures in dusty plasmas in the presence of electromagnetic radiation are investigated. The dust charge variation is assumed to be caused by microscopic electron and ion currents at the grains as well as photoelectric current of electrons. Calculations of electromagnetic radiation effects are performed for the case of solar radiation spectrum in the vicinity of the earth. The exact solutions of the nonlinear equations, describing variable-charge dust grains, Boltzmann electrons, and inertial ions, are obtained in the form of steady-state shocks. The conditions for their existence are found. The dissipation in such shock waves originates from the process of dust charging. The possibility of observation of shock waves related to the dust charging process in the presence of electromagnetic radiation in active rocket experiments which involve the release of some gaseous substance in near-earth space is discussed.

A purely growing instability in a gracitating dusty plasma

Abstract The existence of a purely growing instability in a self-gravitating dusty plasma is demonstrated. The present instability can play a decisive role in levitation/condensation of grains in planetary rings as well as in the formation of galaxies and stars.

Intense solitary laser pulse propagation in a plasma

Previous work [Yu, Shukla, and Tsintsadze, Phys. Fluids 25, 1049 (1982)] on intense laser pulse propagation in plasmas is generalized to include nonlinear ion motion which can be of importance in the slow plasma response.

Generalized magnetohydrodynamic equations for partially ionized dusty magnetoplasmas: Derivation and applications

A comprehensive investigation of electromagnetic wave and instability phenomena in partially ionized, magnetized dusty plasmas has been carried out. By employing the multi‐fluid balance equations along with the Maxwell equations, a compact set of coupled field equations for the cases in which the dust grains are either robust (vd=0) or dynamic is derived. These systems of partial differential equations are used to study wave phenomena and resistive tearing mode instabilities analytically as well as by means of numerical simulations. For robust dust grains, it is shown that coupled sound‐Alfven waves can appear even in the absence of ion‐neutral collisions. The unstable tearing modes are coupled to convective drift modes, if the dust number density is inhomogeneous. In the induction equation two new source terms for self‐generation of magnetic fields can be identified. In parameter regimes that are characterized by dynamic dust grains, the low‐frequency phenomena develop on timescales that are governed by ...