Similarity study of low-pressure microwave argon plasma based on numerical simulation

This article mainly proposes a similarity analysis method for the breakdown process of microwave argon plasma, which can easily obtain high-power microwave (HPM) breakdown features for argon plasma in microwave components with extremely large- or small-scale. The electromagnetic-plasma fluid model is proposed and solved by the finite element method. The preconditions for a similarity principle of gas breakdown in a microwave frequency band are proposed. In plasma breakdown regions with a proportional size, the ratio of incident microwave frequency f to gas pressure p (f/p) and reduced electric field (E/p) in them remain the same. Numerical results show that in the microwave frequency band, the breakdown process between similar structures also conforms to the similarity principle, especially after the argon plasma breakdown region is stabilized, numerical results are in good agreement with the theoretical values. The intensity of electric field is directly proportional to scale-down factor k, electron density is directly proportional to the square of scale-down factor k(2), and electron energy is almost independent of scale-down factor k. Meanwhile, the distribution trends of electric field, electron density, and electron energy during the microwave argon breakdown process are also roughly the same, respectively. This research method can provide theoretical guidance for analyzing the HPM breakdown effect in extremely large or extremely small microwave components.