Generation of a controllable electron density gradient using a single plasma source

In this work, an experimental design for generation of the controllable electron density gradient is achieved through a large area oxide coated cathode and two stainless meshes. The large area oxide coated cathode is adopted to produce a large area, uniform and high density plasma, and these two metal meshes are specially designed to control the density and potential of the plasma. A boundary layer with independent electron density gradient and uniform plasma potential is subsequently generated. The controllable electron density gradient can be achieved, and the accompanied electric field can be compensated simultaneously using this design, which could be potentially extended to study the excitation of the plasma instabilities when the strong plasma density gradient exists.