Formation of electrostatic solitons and hole structures in pair plasmas

In an electron-proton plasma, electrostatic solitary waves and hole structures can easily be generated by streaming instability due to the asymmetric inertia between ions and electrons. It has been argued theoretically whether electrostatic solitons and/or hole structures can form in a pair plasma. This paper presents results on the formation of pair electrostatic hole structure in an electron-positron plasma based on one-dimensional electrostatic particle-in-cell simulations. In particular, we show the feature of interlacing electron and positron holes in phase space generated by current-free electron and positron beams streaming in a stationary electron-positron background plasma. The coexistent electron and positron holes are associated with periodic interlacing of positive and negative potentials, respectively. Detailed comparisons between simulation results and linear theory of streaming instability in pair plasmas are made and the thermodynamic state is inferred.