Weak double layers in ion-acoustic turbulence

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Abstract
The evolution of weak double layers in ion‐acoustic turbulence in one and two‐dimensional particle simulations is examined. Weak double layers (eφ≲Te) evolve in simulations when a subthermal electron drift is imposed on a long or nonperiodic system with Te/Ti≫1. Their growth rate increases with the electron drift, and they decay because of ion trapping. They do not form in weakly magnetized or unmagnetized two‐dimensional (2‐D) systems unless a nonuniformity is introduced in the initial or boundary conditions. When the plasma is strongly magnetized (ωce>ωpe), they emerge from 2‐D ion‐acoustic turbulence as coherent structures localized transversely to the magnetic field.