Genesis of non- uniformity of plasma fluxes over emissive wall in low-temperature plasmas*

A spatial non-uniformity of electron and ion fluxes on the treated surfaces in plasma devices can be provoked by various factors, for example, a non-planar topology, difference in the electron emission yield of materials in segmented surface or the presence of an oblique external magnetic field. In these cases, a feedback between plasma fluxes and surface structure (through the non-planar surface sheath) can lead to an essential modification of the surface during plasma device operation. In PIC MCC simulations and in the experiment, the plasma sheath transition near the grooved emissive surface, segmented emissive surface stimulated by an increase of the energy of electron is studied. It is shown that the modulation electron and ion fluxes to the surface increases after the transition. The effect of external oblique magnetic field on plasma structure is studied in PIC MCC simulations. The formation of periodical plasma structure and effect of variation of electron energy and magnetic field strength on this structure is discussed. It is shown that enlarging the inclination of the magnetic field leads to increasing non-uniformity of ion and electron fluxes on the wall.