Current gradient driven Alfven dipolar vortices in electron-positron-ion plasmas

Linear and nonlinear Alfven waves in an electron-positron-ion plasma are studied in the presence of a background current gradient. The temporal and spatial scales of this electromagnetic perturbation in electron-positron plasma become very different if the ion concentration is about 0.1% or more. The instability criterion becomes dependent upon the concentration of different species in a three component plasma, which is a different result compared to previous studies for two component plasmas. A comparison of this study with the limiting cases of electron-ion and electron-positron plasmas is also presented. This investigation can be applicable to astrophysical plasmas like active galactic nuclei (AGN) and the magnetospheres of pulsars.