Two-way interaction between switching arc and solid surfaces: distribution of ablated contact and nozzle materials

Abstract

Abstract This paper is devoted to two-way plasma-surface interactions by investigating how the plasma arc ablates the nozzle and contacts and how the distribution of ablated materials changes the plasma parameters. For this purpose, a two-dimensional time-dependent model, in axial symmetric coordinates, for an arc at atmospheric pressure burning within a polytetrafluoroethylene nozzle is created. A computational fluid dynamics equations system is solved for plasma velocity, pressure, temperature, magnetic vector potential, and electrical potential. Radiation is modeled based on net emission coefficient and contacts, and nozzle ablation is also considered to better describe the arc formation, contact cooling, and arc temperatures, more precisely. The sublimated materials from contacts and nozzle will be used to calculate the distribution of plasma composition (i.e. ablated mixture ratio). The calculated ratio is used to change the plasma parameters, and data processing techniques are utilized to derive particle distribution and temperature profiles of the arc to investigate its thermo-electrical behavior. The simulation results show good agreement with the measurements obtained in an experimental setup already designed and published. This study provides support to the experimental work and contrariwise. The presence of ablated points on nozzle and contacts, which further modify plasma parameters and therefore the arc voltage are discussed.