Experimental observation and numerical investigation of imposed pattern formation in magnetized plasmas by a wide wire mesh

In this paper, the formation of imposed patterns due to placing a wide wire mesh ('waffle' electrode) in the bulk of a strongly magnetized (B > 1 T) plasma is investigated both experimentally and numerically. A new double head electrostatic probe was designed for the experiments that allows for measurements of the floating potential beneath the mesh in the magnetized plasma. The measurements using this probe revealed that due to the presence of the 'waffle' electrode in the bulk of the magnetized plasma, an organized pattern appears in the plasma potential. As a result of this imposed pattern, when dust particles were added to the experiments, they became trapped beneath the edges of the 'waffle' electrode. The effects of placing a wire mesh in the bulk of a magnetized plasma were further investigated using fluid and particle-in-cell (PIC) simulations. These simulations were able to qualitatively reproduce the experimental observations. The results of the simulations showed that the imposed patterns arise due to differences in the cross-field transport of the electrons and ions in the presence of magnetic field.