An Noval High-efficiency Microwave Plasma Torch

The microwave plasma torch is widely used in industrial production due to its advantages of high energy density and high power. The microwave energy utilization and electric field distribution will affect the performance of the plasma torch, such as electron density, electron temperature, etc. The almost atmospheric pressure plasma torch device has low electric field intensity and poor energy utilization, which makes it difficult to excite and maintain. In this paper, a novel microwave plasma torch is designed based on a gradient index meta-surface, which can increase the electric field strength in the plasma region and allow more energy to flow into the plasma. First, the theory that meta-surfaces convert electromagnetic waves into surface waves is given, and a meta-surface that can manipulate the propagation of electromagnetic waves is designed. Secondly, the microwave driven argon plasma excitation model is established based on the finite element method. The results compared with the conventional compression waveguide show that the proposed method can increase the electric field strength by 3 times under the same input power. Third, a microwave plasma jet measurement system was built to test the excitation power, maintenance power and steady state energy utilization of different gas components. Compared with the traditional microwave plasma torch, the results show that the proposed method has higher performance and is more suitable for industrial applications.