Analysis of Microscale High Pressure Argon Discharges: A Global Model Approach

Microplasma discharges have emerging applications in space micro-thrusters, electronic devices, biomedicine, and more. In this work, we investigated high-pressure argon discharges sustained between two parallel plates with a sub-millimeter spacing via a global model coupled with a sheath model. The role of molecular Ar
2
⁺
and metastable state Ar
2
* are explored. For fixed driving current and gap at atmospheric pressure, the plasma density (mainly e and Ar
2
⁺
) increases first and then gets relatively flat with increasinc driving frequency (0.1-2 GHz), meanwhile, the main loss channel of Ar
2
⁺
transits from wall loss to bulk recombination. Usually, the similarity law is satisfied if the discharge system is sustained by linear processes. Here the effect of nonlinear physical processes such as step-ionization and penning ionization and sheath breakdown due to secondary electron emission on the discharge similarity law will be explored.