Merlino2D: An open-source code for non-thermal gas discharge simulations
Description
We introduce Merlino2D, an efficient fluid plasma solver (available at https://github.com/PTL-Unibo/Merlino2D) for the simulation of low-temperature gas discharges and plasma-based devices. The solver operates on structured and unstructured triangular meshes and supports robust two-dimensional simulations of stationary and time-dependent regimes. Merlino2D integrates the open-source LisbOn KInetics Boltzmann solver (LoKI-B), which computes the electron energy distribution function and associated swarm parameters. The time-dependent drift–diffusion equations coupled with Poisson’s equation are formulated as a monolithic system of differential-algebraic equations (DAEs). The system of equations is integrated in time with a fully implicit time integration scheme with adaptive time stepping and error control. This approach results in efficient handling of numerical stiffness and favorable scaling of the computational time with mesh size. In this work, the numerical methodology underlying Merlino2D is described, and the numerical accuracy of the transport schemes is verified against analytical solutions. In addition, the solver is applied to two-dimensional simulations of both DC and AC discharges, including corona discharges and surface dielectric barrier discharges (DBDs), demonstrating its capability to reproduce experimental trends and results reported in the literature.