Vlasov-Poisson Simulations of Ion Acoustic Waves

We present simulations of ion acoustic waves in a 1D1V spatially periodic domain using an extended version of the FARSIGHT Vlasov-Poisson code, adapted for two-species plasmas. FARSIGHT is a forward semi-Lagrangian scheme with 4th order Runge-Kutta time-stepping and a tree-based adaptively refined particle/panel representation of the distribution functions in phase space. Unlike the particle-in-cell (PIC) method, FARSIGHT computes the electric field as a regularized convolution integral in phase space using a GPU-accelerated barycentric Lagrange treecode. Our results include studies with varying electron-to-ion temperature ratios (T_e/T_i), and we report on several key diagnostics: the damping rate of the electric field, plasma frequency, electron and ion charge densities, and the phase space distribution functions of both species. A recurring irregular feature was observed in the time evolution of the 2-norm of the electric field, exhibiting a temporal period that appears to depend on the maximum velocity of the simulation domain. The cause of this feature is currently under investigation.