Similarity principle of microwave argon plasma at low pressure**Project supported by the National Natural Science Foundation of China (Grant No. 61331002), the National Key Basic Research Program of China (Grant No. 2013CB328903), and the Fundamental Research Funds for the Central Universities, China (Grant No. W15JB00510).

Abstract

In order to validate the similarity principle of microwave breakdown, a two-dimensional (2D) fluid model of low-pressure microwave argon plasma is established and solved by the finite-element method. Proportional conditions are used in this model to build three different breakdown processes that meet the premise of a similarity principle, and these breakdown processes are called “similar cases” in this paper. Similar cases have proportionately sized breakdown regions, where the ratio of frequency of incident microwave f to gas pressure p (f/p), and the reduced field E/p in them are kept the same. All the important physical parameters such as electron density, electron temperature, and reduced electric field can be obtained from the simulation of this model. The results show that the parameters between similar cases are in constant ratio without changing with time, which means that the similarity principle is also valid in microwave breakdown.