On the characteristics of obliquely propagating electrostatic structures in non-Maxwellian plasmas in the presence of ion pressure anisotropy

Abstract

The dynamical characteristics of large amplitude ion-acoustic waves are investigated in a magnetized plasma comprising ions presenting space asymmetry in the equation of state and non-Maxwellian electrons. The anisotropic ion pressure is defined using the double adiabatic Chew-Golberger-Low theory. An excess in the superthermal component of the electron population is assumed, in agreement with long-tailed (energetic electron) distribution observations in space plasmas; this is modeled via a kappa-type distribution function. Large electrostatic excitations are assumed to propagate in a direction oblique to the external magnetic field. In the linear (small amplitude) regime, two electrostatic modes are shown to exist. The properties of arbitrary amplitude (nonlinear) obliquely propagating ion-acoustic solitary excitations are thus investigated via a pseudomechanical energy balance analogy, by adopting a Sagdeev potential approach. The combined effect of the ion pressure anisotropy and excess superthermal electrons is shown to alter the parameter region where solitary waves can exist. An excess in the suprathermal particles is thus shown to be associated with solitary waves, which are narrower, faster, and of larger amplitude. Ion pressure anisotropy, on the other hand, affects the amplitude of the solitary waves, which become weaker (in strength), wider (in spatial extension), and thus slower in comparison with the cold ion case.

The arbitrary amplitude of a solitary pulse propagating obliquely in electron spin‐polarized plasma

“…By multiplying $$$ \frac{d S}{d\xi} $$$ both sides of Equation (11) and then after integration, we get energy conservation equation in the following form (for the detail derivation see appendix in ref. [40]) $$$$ \frac{1}{2}{\left(\frac{d\Phi}{d\xi}\right)}^2+\Psi \left(\Phi, \kappa, M,\Omega \right)=0, $$$$ where $$$$ \Psi \left(\phi, \kappa, M,\Omega \right)={\Omega}^2\frac{\Psi_1\left(\Phi, \kappa, M\right)}{\Psi_2\left(\Phi, \kappa, M\right)}, $$$$ is the “pseudopotential” function, and $$$ {\Psi}_1\left(\Phi, \kappa, M\right) $$$ and $$$ {\Psi}_2\left(\Phi, \kappa, M\right) $$$ given by …”

“…By multiplying dS d𝜉 both sides of Equation ( 11) and then after integration, we get energy conservation equation in the following form (for the detail derivation see appendix in ref. [40]) 1 2…”

“…Later on Sagdeev approach extended for the description of magnetized plasmas. [36][37][38][39][40][41] In this manuscript, we investigated electrostatic ions acoustic solitary waves composed of inertia-less electrons with both spin-up ( n ↑ ) and spin-down…”

Effect of Anisotropic Pressure on Electron Acoustic Oscillatory and Monotonic Shocks in Superthermal Magnetoplasma

“…The electron kinematic fluid viscosity ( μ c ‖,⊥ ) is also normalized into dimensionless parameter (i.e., ). The external magnetic field introduces an anisotropy in the electron pressure which splits the pressure tensor into two components in the directions perpendicular and parallel to the direction of magnetic field (Adnan et al, , ). They studied the effect of anisotropic pressure on nonlinear ion acoustic excitations in magnetized e‐p‐i plasmas by employing Sagdeev pseudo‐potential and reductive perturbation technique under the influence of superthermal distribution.…”

Effect of Pressure Anisotropy on Nonlinear Periodic Waves in a Magnetized Superthermal Electron-Positron-Ion Plasma

“…In such situations, one needs to solve two energy equations associated with the thermal pressures p and p ⊥ (relative to the magnetic filed). The features of such anisotropic system can be uncovered by theory presented by Chew-Golberger-Low in 1956, famous as (CGL) or double adiabatic theory [31][32][33].…”