A 3-D model of microwave argon plasma (Ar-MIP) under atmospheric pressure is established with the finite element method to describe the temporal and spatial distribution of plasma temperature, pressure, and velocity. The interaction of these parameters is studied to explore the mechanism of microwave plasma excitation. The results show that the plasma temperature increases upon increasing the time, and the high temperature distribution exhibits spatial inhomogeneity, which causes the local changes in gas pressure and affects the flow velocity leading the thermal flow around the heat area. This is the reason that the fluid in high temperature region slows down.
