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

Abstract

Abstract. Dielectric barrier discharges (BDs) are known to operate in two distinctive modes. Filamentary mode of DB is characterized by 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 covers uniformly the whole electrode area. This mode is usually referred to as diffuse or homogeneous mode of BD.This work presents studies of filamentary mode of BD in argon and its transition to the diffuse mode by ammonia addition. The discharges were investigated by the means of Cross Correlation Spectroscopy (CCS). Particularly the influence of electrode shape, discharge gap and 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 configuration is presented. When compared to 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.

Modeling of plasma chemistry in an atmospheric pressure Ar/NH3 cylindrical dielectric barrier discharge described using the one-dimensional fluid model

“…The behavior is consistent with the standard behavior of the dielectric barrier discharge as described in Ref. 5.…”

“…The cross-correlation spectroscopy measurements were carried out for the different ammonia concentrations (0.1%, 1.0%, and 5.0%). 5 The observed changes were similar to Ref. 6-appearance of NH bands, a decrease in argon line intensity nearly one hundred times, thus highly reducing overall light intensity of the discharge.…”

“…It causes the maximum of the electron energy distribution function in the lower energy range. 5 Thanks to the lower threshold energy of NH x ionization than that of Ar, it prior to produce NH þ x ions. On the positive ammonia ion ratio, it can be explained that charge exchange between Ar þ and NH, NH 2 , NH 3 produce the respective NH þ x ions.…”

“…6 The optical emission spectroscopy measurements were carried out for the different ammonia concentrations (0.1%, 1.0%, and 5.0%). 5 The difference of NH density can refer to the experimental results in Ref. 5.…”

Metal Carbonyl Vapor Generation Coupled with Dielectric Barrier Discharge To Avoid Plasma Quench for Optical Emission Spectrometry

“…In a helium microplasma generated by a parallel-plate DBD with a gas gap of 0.7−4.5 mm at atmospheric pressure (Figure 4), no optical emission of nickel is detected. This is due to the fact that helium generates a homogeneous microplasma in the above condition, 42 where the relatively low electron and current densities reduce the capability of DBD for molecular dissociation and excitation. On the other hand, however, in a cylindrical DBD excitation source, optical emission of nickel could be readily recorded, and a much higher emission is obtained in argon DBD microplasma with respect to that achieved in helium DBD.…”