An investigation of dielectric barrier discharge in Ar and Ar/NH₃ mixture using cross-correlation spectroscopy

Abstract

Dielectric barrier discharges (BDs) are known to operate in two distinctive modes. The filamentary mode of BD is characterized by a large number of short lasting spatially bounded microdischarges. This type of discharge is typical for most cases of BDs at atmospheric pressure. Under some specific conditions another form of BD may arise. In this mode plasma uniformly covers the whole electrode area. This mode is usually referred to as the diffuse or homogeneous mode of BD. This work presents studies of the filamentary mode of BD in argon and its transition to the diffuse mode by ammonia addition. The discharges were investigated by means of cross-correlation spectroscopy. Particularly, the influence of electrode shape, discharge gap and the influence of ammonia admixture on discharge development were studied. The measurement offers results with high temporal and spatial resolution which are useful for comparison with results of numerical models. The obtained results include the electrical current measurement of discharge in several ammonia admixtures to argon. The diffuse discharge appeared at ammonia admixture above 3 vol%. The observed propagation of streamer in discharge in pure argon for two different electrode configurations is presented. When compared with discharge in pure argon the streamer velocity is decreased for 0.1 vol% ammonia admixture. With increasing ammonia concentration the streamer velocity increases again. The behaviour of presented impurities was observed and the results are included in this report. The basic model of the discharge kinetic is included. For reduced electric field below 10 Td the electron drift is much higher in argon–ammonia mixture than in pure argon.