A 3D numerical analysis on magnetic field enhanced microwave linear plasma

摘要

Microwave linear plasma has attracted a lot of attention due to the outstanding characteristics such as high electron density, low electron temperature, no-pollution, and homogenization, which can realize a large-area uniform plasma source through vertical or horizontal arrangement especially. In order to explore the effect of the permanent magnets and the microwave coaxial reflective antenna on density and uniformity of plasma, a three-dimensional numerical model is established. It is expected to obtain a superior microwave linear plasma source with high density and uniformity for fabricating a carbon film such as graphene or surface treatment. The results show that (1) permanent magnets can improve the density and uniformity of plasma by generating a suitable magnetic field. At the microwave power of 800 W at 20 Pa, the permanent magnets with 150 kA/m enhance the average electron density by 36.67% and control the relative deviation of electron density within ?3% to 1% at an axial distance of 100 mm–300 mm. (2) The reflective antenna can effectively regulate the shape and the uniformity of plasma. The semicylinder reflective antenna realizes the relative deviation of electron density within ?2% to 0.5%. Meanwhile, the average electron density increases by 3.75% between an axial distance of 100 mm and 300 mm under a microwave power of 800 W at 20 Pa. (3) The external magnetic field and reflective antenna also have the regulation on heavy particles (Ars) in plasma, which is an important factor for application.