Nonlinear electrostatic modes in astrophysical plasmas with charged dust distributions

Abstract

Context. Most theoretical investigations of wave phenomena in dusty plasmas have treated charged dust as additional heavy negative ions in standard multispecies models. Many dusty plasma experiments use monodisperse grains, but charged (and neutral) grains in space environments come in a whole range of sizes and compositions, hence in masses and charges. Dust density distributions having a power-law decay with size are often observed in planetary rings. Aims. There is a need to investigate larger solitary structures, since wave descriptions involving charged dust distributions have usually been limited to linear or weakly nonlinear modes. Methods. Sagdeev pseudopotential methods describe large-amplitude solitary waves in a co-moving reference frame and are adapted to include dust distributions, using mass and charge, or alternatively size, as additional variables. Observed power-law distributions lead to descriptions involving hypergeometric functions. Results. Lower limits for possible solitary wave velocities follow from requiring that the Sagdeev pseudopotentials have a local maximum for the undisturbed conditions, whereas upper limits come from ensuring that dust densities remain real. Nonlinear amplitudes increase with solitary wave velocities and relative electron temperature. Under similar plasma conditions, dust size distributions admit slower solitary wave solutions, with correspondingly smaller amplitudes than given by monodisperse dust models. For typical planetary ring conditions, the difference can be quite appreciable.

Gravito-electrostatic fluctuations of a polytropic charged dust cloud

“…A spatiotemporal shape-analysis further confirms their stabilities and periodicities. The results may offer new theoretical supports, with additional dimension of polytropism, to the different earlier predictions widely made by others in normal astrophysical [5][6][7][8][9], space [10][11][12][13][14][15] and cloud [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] environments. An elaborate discussion of the polytropic eigenmode features under periodic gravito-electrostatic interplay together with nontrivial astrophysical implications and future directions is briefly presented.…”

“…Many authors have discussed the various dynamical aspects of linear as well as nonlinear plasma waves and instabilities in dusty space and astrophysical plasmas [4][5][6][7][8][9][10][11][12][13][14][15]. They have studied different types of nonlinear waves and structures, such as solitary waves, shock waves, double layers, vortices, voids, etc [3][4][5][6].…”

“…They have studied different types of nonlinear waves and structures, such as solitary waves, shock waves, double layers, vortices, voids, etc [3][4][5][6]. Verheest et al [12][13][14] have studied the nonlinear behavior of dust acoustic waves including both cold and hot isothermal electrons together with isothermal ions without [12] and with [13][14] grain-size (power-law) distribution taken into account. In a strong nonlinear regime, the Sagdeev potential approach has been adopted to investigate the properties of both rarefactive and compressive solitary patterns for different dust species included there.…”

“…In addition, a distinction between their different amplitudes resulting in different amplitude-velocity correlations has also been reported. As is known and explained elsewhere [12][13][14][15], the Sagdeev potential approach is valid for a fully nonlinear analysis (with arbitrary amplitude) in contrast with multiple scaling techniques (also known as reductive perturbation techniques) meant for weak fluctuations. In addition to the above, several other authors have also methodologically applied the latter techniques to study the stability behaviors of diverse astrophysical dust clouds resulting in miscellaneous solitary, shock-like and hybrid spectral patterns amid inhomogeneous self-gravity on the Jeans scales of space and time [16][17][18][19][20].…”

Effect of particles attachment to multi-sized dust grains present in electrostatic sheaths of discharge plasmas

“…However, the assumption of mono-sized dust grains may not be valid, and the dust size may indeed vary from nanometer to micrometer. Other researchers [22][23][24][25][26][27][28][29] have investigated the effect of dust size distribution on waves propagating in plasmas. Recently, Benlemdjaldi et al 7 plasmas without considering particles attachment to dust grains.…”