Electromagnetic ghosts in pair plasmas

TL;DR

This paper investigates how weakly nonlinear counter-propagating electromagnetic pulses in pair plasmas create long-lasting localized wave structures, termed electromagnetic ghosts, influenced by plasma density fluctuations and magnetic fields.

Contribution

It introduces the concept of electromagnetic ghosts formed by wave trapping in pair plasmas and analyzes their dependence on plasma conditions and magnetic fields.

Findings

Localized wave structures can persist for long times in pair plasmas.

High guide magnetic fields suppress the formation of electromagnetic ghosts.

Wave trapping is analogous to Anderson localization in disordered media.

Abstract

Collisions of two weakly nonlinear, $a_0 \ll 1$, counter-propagating EM pulses in pair plasma leave behind a long-surviving collection of localized waves, {\it an electromagnetic ghost}. Waves are trapped (localized) by the random large density fluctuations created by the beat between the pulses. The process is similar to random plasma density grating and/or Anderson-like wave localization. Structures survive for long, mesoscale times, while the EM energy slowly bleeds through high density walls of the density trap. Large guide magnetic field, $\omega_B \geq $ few $\omega$, suppresses the formation of the ghosts.