S. R. Pillay

Arbitrary amplitude dust-acoustic double layers in a non-thermal plasma

The existence of large-amplitude dust-acoustic double layers is investigated in an unmagnetized dusty plasma comprising a negatively charged warm dust fluid, non-thermal ions and Boltzmann electrons. It is found that the non-thermal plasma supports the existence of rarefactive double layers only. The dependence of the double-layer amplitude and Mach number on various parameters such as the non-thermal parameter, dust temperature and electron concentration is numerically examined.

The Effect of Dust Grain Temperature and Dust Streaming on Electrostatic Solitary Structures in a Non-Thermal Plasma

The influence of dust temperature and dust streaming on dust acoustic solitary waves is investigated in an unmagnetized dusty plasma comprising negatively charged dust, non-thermal ions and Boltzmann electrons. It is found that the conditions which support the coexistence of both compressive and rarefactive solitons is altered by the dust temperature and by dust streaming.

Self-similar expansion of dusty plasmas

The radially symmetric self-similar expansion of a dusty plasma is investigated in cylindrical and spherical geometries. The electrons and ions are assumed to be in Boltzmann equilibria, while the dynamics of the dust particles is governed by the fluid equations. The effects of finite dust pressure as well as dust-charge variation are included.

Linear electrostatic waves in two-temperature electron–positron plasmas

Linear electrostatic waves in a magnetized four-component, two-temperature electron–positron plasma are investigated, with the hot species having the Boltzmann density distribution and the dynamics of cooler species governed by fluid equations with finite temperatures. A linear dispersion relation for electrostatic waves is derived for the model and analyzed for different wave modes. Analysis of the dispersion relation for perpendicular wave propagation yields a cyclotron mode with contributions from both cooler and hot species, which in the absence of hot species goes over to the upper hybrid mode of cooler species. For parallel propagation, both electron-acoustic and electron plasma modes are obtained, whereas for a single-temperature electron–positron plasma, only electron plasma mode can exist. Dispersion characteristics of these modes at different propagation angles are studied numerically.

Arbitrary amplitude dust-acoustic solitons in a weakly non-ideal plasma with non-thermal ions

The nonlinear propagation of the dust-acoustic wave is investigated in a weakly non-ideal plasma comprising Boltzmann electrons, non-thermal ions characterized by a non-thermal parameter α and a negatively charged dust fluid. The non-ideal dust fluid is represented by the van der Waals equation of state. Arbitrary amplitude soliton solutions are found to occur for both supersonic and subsonic values of the Mach number. Upper and lower limits of the range of values of a for which solitons exist are examined as a function of the non-ideal parameters associated with the effects of volume reduction and the cohesive forces, for both the supersonic and subsonic cases.

A parametric study of the influence of non-thermal ions on linear dust-acoustic waves in an unmagnetized dusty plasma

The influence of non-thermal ions on linear dust-acoustic waves is studied in an unmagnetized plasma consisting of ions which have a non-thermal velocity distribution, Boltzmann-distributed electrons and streaming dust particles. A detailed examination is conducted of the dependence of the real frequency and growth rate of the excited instability on the dust drift speed, temperature, particle densities and the parameter a that determines the non-thermal nature of the energetic ions. Comparisons with approximate analytical solutions are also made.

Electrostatic nonlinear waves in a dusty plasma with positive dust grains and two electron species

The existence of arbitrary amplitude nonlinear electrostatic waves is investigated for a plasma with positively charged dust in the presence of two-temperature electron species. It is shown that such a plasma supports both soliton and double layer structures.

Solitary potential structures in presence of non-thermal electrons

Arbitrary amplitude electron-acoustic solitary waves are studied in an unmagnetized plasma consisting of non-thermally distributed electrons, fluid cold electrons, electron beam and ions using the Sagdeev psuedo-potential method. Positive potential solitary structures are obtained for the typical auroral region parameters. The electric field amplitude amplitude of these potential structures ranges from few mV/m to 200 mV/m.

Electrostatic solitary waves in a plasma with dust grains of opposite polarity and non-thermal ions

The existence of large amplitude solitons is examined in a dusty plasma comprising two dust fluids of opposite polarity (including dust pressure effects for the positive dust), Boltzmann electrons and non-thermal ions. The various parameter regimes which support the existence of solitons are investigated by studying the effects of varying particle densities, ratio of the masses and charges of the positive and negative dust grains, temperature of the positive dust grains and, in particular, the ion non-thermal parameter. It is found that both positive and negative potential solitons are found to coexist in some regions of parameter space. The critical minimum value of the Mach number for the existence of soliton solutions is determined via Taylor expansion.

Nonlinear electrostatic waves in a magnetized dusty plasma with two‐temperature ions

Nonlinear low frequency electrostatic waves which arise from the coupling between two linear modes, viz., the dust‐acoustic and dust‐cyclotron waves, are studied in a magnetized dusty plasma comprising Boltzmann electrons, a negatively charged warm dust fluid, and two ion species of different temperatures with both species having isothermal Boltzmann distributions. The fluid equations for the dust are combined with the quasineutrality condition to obtain a single equation which governs the nonlinear evolution of the electric field for wave propagation oblique to an external magnetic field. The numerically obtained solutions for the electric field are found to have sinusoidal waveforms for small values of the initial driver electric field amplitudes and Mach numbers, whereas, spiky structures are found to be supported for larger values. Furthermore, the periods of the waveforms are found to depend on various plasma parameters such as hot and cool ion number densities and temperatures, dust drift speed and ...