Investigation of the arcing and decay processes of arc in SF6 and N2 gas by laser Thomson scattering

The arc discharge is directly related to the success of the current interrupting in switching apparatus in high-voltage electrical equipment. To diagnose the arc plasma, it is essential to use the Thomson scattering method which has better measurement accuracy and spatiotemporal resolution than other optical diagnostic methods. The laser Thomson scattering method has been widely used in diagnosing various plasmas in recent years because it does not rely on the local thermodynamic equilibrium (LTE) and the axial symmetry hypothesis. In this work, the arcing and arc decay processes of SF
6
and N
2
gas arcs were diagnosed using the Thomson scattering method, and a series of electron density evolution results were obtained. As time passes, the edges of the arc column in both the SF
6
gas arc and N
2
gas arc gradually reduce, leading to an overall decrease in electron number density. When compared with the N
2
gas arc, the SF
6
arc has a thinner arc column and a more extensive range of contraction during the arcing and decay processes. Furthermore, the SF6 arc has a lower electron number density, and its decay rate is faster at all times.