Three-dimensional particle-in-cell simulations are performed to study the characteristics of xenon mesothermal plasma plumes and their interaction with the neutralizer electrons. To study the effect of electron source location on the plume dynamics and electron kinetics, two configurations are modeled, one with co-located electron and ion sources and the second with a shifted electron source. In addition, the effect of electrostatic boundary condition on the plume dynamics of the shifted electron case are also studied by implementing a fixed Dirichlet boundary condition of φ =0 V at all the boundaries. In the first case, the plume achieved a quasi-neutral state by the electrostatic trapping of electrons within the confined xenon ion plume. For the shifted electron source, however, no such symmetry was observed and the electrons are found to oscillate, resulting in counterstreaming electron populations. Compared to the Neumann boundary condition, the case with the Dirichlet boundary condition was found to affect the electron velocities as the beam-front approached closer to the boundary, consequently affecting the plume dynamics.