Application of supercritical nitrogen as a promising medium in electric equipment

In allusion to the deficiency of SF6 which is a widely used insulating medium in high voltage electric apparatus, it is necessary to search a alternative medium with excellent interrupting performance and harmless to the environment. Supercritical fluid (SCF) which is in the intermediate state of gas and liquid, with many unique physical and chemical properties combines the advantages of gas and liquid: high ability of mass transfer and high heat transfer. And SCF has high breakdown strength and fast dielectric recovery capability after breakdown, therefore, SCF has a high potential as an insulating medium. In this article, the molecular dynamics (MD) of supercritical nitrogen under different electric fields is researched by analyzing Radial Distribution Function (RDF) and Mean Square Displacement (MSD). The simulation results indicate that: the clusters of nitrogen molecule are reduced and the first neighbor structure of nitrogen is weakened by applying an electric field. Meanwhile, the molecular diffusion is influenced by the molecular polarization under electric field, and in the electric field of 103~109 V/m, the nitrogen diffusion coefficient increases first and then decreases.