Preferential acceleration and magnetic field enhancement in plasmas with e+/e- beam injection

Abstract

A theoretical model of current filaments predicting preferential acceleration/deceleration and magnetic field enhancement in a plasma with e(+)/e(-) beam injection is presented. When the e(+)/e(-) beams are injected into a plasma, current filaments are formed. The beam particles are accelerated or decelerated depending on the types of current filaments in which they are trapped. It is found that in the electron/ion ambient plasma, the e(+) beam particles are preferentially accelerated, while the e(-) beam particles are preferentially decelerated. The preferential particle acceleration/deceleration is absent when the ambient plasma is the e(+)/e(-) plasma. We also find that the particle momentum decrease can explain the magnetic field increase during the development of Weibel/filamentation instability. Supporting simulation results of particle acceleration/deceleration and magnetic field enhancement are presented. Our findings can be applied to a wide range of astrophysical plasmas with the e(+)/e(-) beam injection. (C) 2016 AIP Publishing LLC.