Generation of Long Laminar Plasma Jets: Experimental and Numerical Analyses

A novel direct current non-transferred arc plasma torch that can generate silent, stable and super-long laminar plasma jets in atmospheric air is investigated. The results showed that laminar plasma jets of length ranging from 100 to 720 mm in length can be generated by controlling the gas input rate ranging from 8.5 to 15 L min ⁻¹ and the output power from 8.5 to 28 kW. The length of the plasma jets generally increased with the output power and gas flow rate. Observations of temporal evolution of the plasma jet appearance and the voltage demonstrated that the jet is highly stable in the atmospheric environment. The fluid dynamic properties of the laminar plasma jet were studied using a numerical simulation incorporating a laminar flow model and an RNG turbulent flow model. Simulation results show the expansion of a high temperature region close to the torch nozzle exit, corresponding to a bright region observed in experiments.