Electrostatic solitary waves in an electron-positron pair plasma
with suprathermal electrons

Ashkbiz Danehkar
Centre for Plasma Physics, Queen's University Belfast, Belfast BT7 1NN, UK
Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia
Present Address: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA

Date: Received 19 August 2017; accepted 11 October 2017; published online 26 October 2017


The nonlinear propagation of electrostatic solitary waves is studied in a collisionless electron-positron pair plasma consisting of adiabatic cool electrons, mobile cool positrons (or electron holes), hot suprathermal electrons described by a $ \kappa $ distribution, and stationary ions. The linear dispersion relation derived for electrostatic waves demonstrates a weak dependence of the phase speed on physical conditions of positrons in appropriate ranges of parameters. The Sagdeev's pseudopotential approach is used to obtain the existence of electrostatic solitary wave structures, focusing on how their characteristics depend on the physical conditions of positrons and suprathermal electrons. Both negative and positive polarity electrostatic solitary waves are found to exist in different ranges of Mach numbers. As the positrons constitute a small fraction of the total number density, they slightly affect the existence domains. However, the positrons can significantly change the wave potential at a fixed soliton speed. The results indicate that the positive potential can greatly be grown by increasing the electron suprathermality (lower $ \kappa $) at a fixed true Mach number. It is found that a fraction of positrons maintain the generation of positive polarity electrostatic solitary waves in the presence of suprathermal electrons in pair plasmas.
Keywords: hot carriers, electron beams, plasma electrostatic waves, nonlinear processes, plasma solitons
PACS Nos.: 52.27.Ep, 52.35.Fp, 52.35.Mw, 52.35.Sb
Journal Reference: A. Danehkar. Physics of Plasmas, 24(10):102905/1-9, 2017. doi:10.1063/1.5000873

Ashkbiz Danehkar