Experimental characterization of an atmospheric argon plasma jet generated by an 896 MHz microwave system

This paper presents experimental results on an atmospheric plasma jet generated by a rectangular wave-guide based microwave system operating at 896 MHz. Argon gas emerging from a copper nozzle, which is placed inside the wave-guide short circuited at one end (hereafter referred to as the cavity for convenience), jets into the atmosphere through an aperture in the cavity wall. The plasma jet can be visually divided into two parts: a very bright patch (active zone) where microwave discharge takes place and a large, weakly illuminating tail attached to the active zone. The plasma Jet is characterized in this work by measuring the electron number density, temperature and an excitation temperature of the argon atoms in the active zone over a range of microwave source power from 2 to 5 kW and argon flow rate from 2 to 7 litre min(-1). Results show that the plasma is not in a local thermodynamic equilibrium state and the temperature of electrons is considerably higher than the excitation temperature of the heavy particles which indicates the upper limit of the translation temperature of the heavy particles.