Normal mode analysis of pair plasma with drifting species

Abstract

Pair-ion plasmas consisting of C60+ and C60- ions have been generated in laboratory using fullerene as an ion source1,2. In addition, electron-positron plasmas are believed to be abundant in many astrophysical environments from pulsars to quasars3,4. In laboratory also, electron-positron pair plasma has been generated with the help of ultraintense lasers5 and by trapping of positron in a magnetic mirror configuration by electron cyclotron resonance heating6. Since plasmas are nonlinear and dispersive media, it would be very much interesting to examine whether such pair-plasmas support the excitation of solitary waves and solitons. This has motivated us to do analytical calculations for studying the modes of solitary wave propagation. One-dimensional two-fluid plasma having streaming positrons and electrons is studied through normal mode analysis. We analyze how many types of modes propagate in these plasmas and also compare our results with previously explored models by other researchers. We obtained the dispersion relation and solved for the phase velocity of the acoustic modes. Although the dispersion relation predicts four types of the modes, only two types of the modes (namely fast and slow mode) are possible in the present plasma model. We find all the roots to be real. Therefore, it may be inferred that the instability may be possible in the present plasma model.