Validation simulations of the Particle-in-Cell code hPIC with the Laser-Induced Fluorescence measurements at the HELIX facility*

We report clear evidence of the three-dimensional structure of the ion flow in a magnetic presheath formed at the plasma-wall transition, using both Particle-In-Cell simulations using the hPIC code, and experimental measurements of the ion flow conducted at the HELIX facility at West Virginia University using 3D Laser Induced Fluorescence. The PIC-MCC simulations are performed using the fully kinetic, full-orbit PIC code hPIC with heavy ions (argon) and adiabatic electrons. The experiments are run in conditions of intermediate magnetization with magnetized electrons and weakly unmagnetized ions ($\omega \tau \approx 1$). Based on the results of the simulations and experiments, we demonstrate how the structure of the plasma sheath can significantly be altered by the drifts of the background gas and/or the ambient electric fields. Finally, we highlight the relevance of inclusion of the collisional processes for achieving a quantitative agreement of PIC simulations with the experiments.