DOLI II upgrade and future investigation of the sheath structure in the presence of an ion beam

New features are being added to a triple plasma device at UW-Madison, DOLI-II (originally, Double Layer Investigator) that include a biasable, movable boundary plate, and collection optics for laser-induced fluorescence (LIF) in the central plasma chamber. The device consists of a central chamber and two outer chambers with biased grids placed in between. Plasma can be produced in each outer chamber by thermionic electrons which are emitted from the biased filament. Energetic ions are driven by the biased grids into the main chamber. The influence of the ion beam on the sheath structure in front of the boundary plate will be investigated. Plasma parameters are measured by the Langmuir probe, emissive probe, and LIF. The new features of DOLI will be presented here as well as some preliminary results.