Eur. Phys. J. D (2014) 68: 247
https://doi.org/10.1140/epjd/e2014-50384-y

Regular Article

Pressure anisotropy effects on nonlinear electrostatic excitations in magnetized electron-positron-ion plasmas

¹ Institute of Physics and Electronics, University of Peshawar, 25000 Peshawar, Pakistan
² Centre for Plasma Physics, Department of Physics and Astronomy, Queen’s University Belfast, BT7 1NN, Northern Ireland, UK
³ Theoretical Physics Division (TPD), PINSTECH P.O. Nilore, 44000 Islamabad, Pakistan

^a e-mail: adnanphysiks@yahoo.com

Received: 14 May 2014
Received in final form: 21 June 2014
Published online: 11 September 2014

Abstract

The propagation of linear and nonlinear electrostatic waves is investigated in a magnetized anisotropic electron-positron-ion (e-p-i) plasma with superthermal electrons and positrons. A two-dimensional plasma geometry is assumed. The ions are assumed to be warm and anisotropic due to an external magnetic field. The anisotropic ion pressure is defined using the double adiabatic Chew-Golberger-Low (CGL) theory. In the linear regime, two normal modes are predicted, whose characteristics are investigated parametrically, focusing on the effect of superthermality of electrons and positrons, ion pressure anisotropy, positron concentration and magnetic field strength. A Zakharov-Kuznetsov (ZK) type equation is derived for the electrostatic potential (disturbance) via a reductive perturbation method. The parametric role of superthermality, positron content, ion pressure anisotropy and magnetic field strength on the characteristics of solitary wave structures is investigated. Following Allen and Rowlands [J. Plasma Phys. 53, 63 (1995)], we have shown that the pulse soliton solution of the ZK equation is unstable to oblique perturbations, and have analytically traced the dependence of the instability growth rate on superthermality and ion pressure anisotropy.