Analysis on thermophysical properties of arc plasmasin gas sealed relay

The thermophysical properties of arc plasma are essential for setting up physical model of a gas sealed relay. In order to obtain the thermophysical data of N2-Ag arc plasmas in the condition that temperature ranges from 300 to 20000 K, pressure is 0.1, 0.4, 0.8 and 1.0 MPa, and proportion of Ag vapor is 1%, 10% and 50%, respectively, the thermodynamic properties of N2-Ag arc plasmas are calculated using Gibbs free energy minimization. New potential model is adopted to calculate collision integrals of N2-Ag arc plasmas, thus the transport properties are determined. Emphasis is put on the evolution of thermophysical properties under different pressures and silver vapor proportions. The results indicate that increasing pressure can suppress the decomposition reaction and ionization reaction in arc plasmas. When the proportion of Ag vapor reaches 50%, it has a significant impact on the thermophysical properties. The data obtained in this study are validated by literatures, so they can be applied to modelling and simulation of arc plasma in gas sealed relay with silver contacts.