Studies of sheath characteristics in a double plasma device with a negatively biased separating grid and a magnetic filter field

摘要

A double plasma device has two regions: Source region and target region. These two regions are divided by a magnetic filter field. A grid is placed coplanar to the magnetic filter. To study the sheath structure in the target region, a metallic plate is placed at the center, which can be biased with respect to the chamber (ground) potential. Plasma is created in the source region by filament discharge technique. Plasma diffusing from the source region to the target region is subjected to the magnetic filter field and also an electric field applied on the grid. Plasma thus obtained in the target region forms a sheath on the biased plate. The influence of both the magnetic filter field and the electric field, applied between the grid and the chamber wall, on the sheath structure formed on the biased plate is studied. It is found that the magnetic filter field and the electric field change the sheath structure in different ways.