ALBERT

Notes: The theory of stimulated scattering of a light wave in a dusty plasma is re-examined, taking into account the dust charge fluctuations. It is shown that the latter somewhat modify the dust-acoustic waves which are involved in the scattering process. The present results significantly improve those of Lee [Phys. Plasmas 8, 5053 (2001)]. © 2002 American Institute of Physics.

Notes: A theoretical investigation is carried out for understanding the properties of obliquely propagating electron-acoustic solitary waves (EASWs) in a magnetized plasma whose constituents are a cold magnetized electron fluid, hot electrons obeying a vortex-like distribution, and stationary ions. It is found that the present plasma model supports EASWs having a positive potential, which corresponds to a dip (hump) in the cold (hot) electron number density. The effects of the external magnetic field and the obliqueness are found to significantly change the basic properties (viz. the amplitude and the width) of the EASWs. The present investigation can be of relevance to the electrostatic solitary structures observed in various space plasma environments (viz. the cusp of the terrestrial magnetosphere, the geomagnetic tail, the auroral regions, etc.). © 2002 American Institute of Physics.

Notes: The properties of cylindrical and spherical dust ion–acoustic solitary waves (DIASWs) in an unmagnetized dusty plasma, whose constituents are inertial ions, Boltzmann electrons, and stationary dust particles, are investigated by employing the reductive perturbation method. The modified Korteweg–de Vries equation is derived and its numerical solutions are obtained. It has been found that the properties of the DIASWs in a nonplanar cylindrical or spherical geometry differ from those in a planar one-dimensional geometry. © 2002 American Institute of Physics.

Notes: 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 because it has many potential applications in astrophysics (viz. in understanding the formation of dust clusters and structures, instabilities of interstellar molecular clouds and star formation, decoupling of magnetic fields from plasmas, etc.) as well as in the planetary magnetospheres of our solar system [viz. Saturn (particularly, the physics of spokes and braids in the B and F rings), Jupiter, Uranus, Neptune, and Mars] and in strongly coupled laboratory dusty plasmas. Since a dusty plasma system involves the charging and dynamics of massive charged dust grains, it can be characterized as a complex plasma system providing new physics insights. In this paper, the basic physics of dusty plasmas as well as numerous collective processes are discussed. The focus will be on theoretical and experimental observations of charging processes, waves and instabilities, associated forces, the dynamics of rotating and elongated dust grains, and some nonlinear structures (such as dust ion-acoustic shocks, Mach cones, dust voids, vortices, etc). The latter are typical in astrophysical settings and in several laboratory experiments. It appears that collective processes in a complex dusty plasma would have excellent future perspectives in the twenty-first century, because they have not only potential applications in interplanetary space environments, or in understanding the physics of our universe, but also in advancing our scientific knowledge in multidisciplinary areas of science. © 2001 American Institute of Physics.

Notes: It is shown that oscillating dipoles of elongated grains (dipole oscillons) can create oscillatory wake potentials which can focus ions and attract nonspherical grains having the same polarity. This may provide the possibility for the formation of a linear ordered structure, which has been observed in association with ultra-low low-frequency oscillations in a liquid plasma crystal [V. Molotkov et al., JETP Lett. 71, 102 (2000); Rahman et al., Phys. Scr. T 89, 186 (2001)]. © 2001 American Institute of Physics.

Notes: A number of different types of obliquely propagating dust-associated electrostatic drift-like waves, namely, the Shukla–Varma mode, the lower-hybrid mode, coupled electron–drift–dust–ion–acoustic waves, coupled ion–drift–dust–electron–acoustic waves, coupled dust–drift–dust–acoustic waves, and coupled dust–drift–dust–cyclotron waves, in a nonuniform bounded dusty magnetoplasma are theoretically investigated. The last two are studied by considering the dynamics of the negatively charged dust grains, whereas the other ones are studied by considering the presence of the static dust grains. The dispersion properties of these drift-like waves, which are found to be significantly modified by the combined effects of plasma density inhomogeneity, finite boundary of the dusty plasma, obliqueness of the propagating mode, and external magnetic field, are examined. The relevance of this investigation to low-temperature laboratory dusty magnetoplasmas is discussed. © 2000 American Institute of Physics.

Notes: It is shown that the ponderomotive force of finite amplitude shear (or kinetic) Alfvén waves can generate magnetic field-aligned quasistationary density humps as well as dips. The results can have relevance to the shear Alfvén 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. © 2000 American Institute of Physics.

Notes: Properties of dust ion-acoustic (DIA) shocks and DIA holes are examined, assuming that a dusty plasma contains immobile charged dust grains, warm electrons, and warm ions. A Kortweg-deVries- Burgers equation for DIA shocks is derived by employing the hydrodynamic equations for the warm ion fluid and the Boltzmann electron density distribution. On the other hand, DIA holes arise when the warm ions follow a trapped vortex distribution. The profiles of DIA shocks and DIA holes are discussed. The results are useful for understanding the salient features of DIA shocks and holes that are recently observed in laboratory dusty plasma devices. © 2000 American Institute of Physics.

Notes: The electromagnetic effects are incorporated in the study of toroidal ion-temperature-gradient (ITG) modes in a nonuniform magnetoplasma. For this purpose, dispersion relations have been derived by employing the fluid and gyrokinetic responses for the ions, as well as the fluid electron response along with Ampère's law. The dispersion relations are numerically analyzed and results for the real and imaginary parts of the ITG wave frequencies are displayed for different values of cursive-epsilonn=2Ln/LB (where Ln and LB are the characteristic scale lengths of the density and magnetic field gradients, respectively) and λi(parallel)=k(parallel)λi, where k(parallel) is the parallel component of the wave vector and λi is the collisionless ion skin depth. It is found that electromagnetic effects are stabilizing. Furthermore, also presented are brief calculations of particle as well as ion thermal transports in the presence of nonthermal electromagnetic fluctuations. The relevance of this investigation to the plasma confinement in tokamaks is discussed. © 2000 American Institute of Physics.

Notes: The nonlinear interaction between broadband Langmuir waves and electrostatic dust–acoustic perturbations in a uniform collisional dusty plasma is considered, taking into account the combined effects of the Langmuir wave ponderomotive force and the electron Joule heating nonlinearity. This coupling is governed by a Liouville equation for a Langmuir wave packet and an equation for a dust–acoustic perturbation that is driven by the ponderomotive and thermal forces of the random phase Langmuir waves. The mode coupling equations are then Fourier decomposed to derive the nonlinear dispersion relation. The latter is analyzed numerically for a Gaussian Langmuir wave spectrum, by taking parameters that are relevant for low-temperature dusty plasma discharges. It is found that a broadband spectrum of Langmuir waves is subjected to a rapidly growing modulational instability in a dusty plasma. © 2000 American Institute of Physics.