Characterization of transient discharges under atmospheric-pressure conditions applying nitrogen photoemission and current measurements

Abstract

Abstract.The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each other and resolve problems, which arise when these methods are used individually. Nitrogen is used as sensor gas and is admixed in low amount to argon for characterizing the APC discharge. Both direct and stepwise electron impact excitation of nitrogen emissions are included in the plasma-chemical model applied for characterization of these transient discharges using OES where ambiguity arises in the determination of plasma parameters at specific discharge conditions. It is shown that the measured current solves this problem by providing additional information useful for the determination of discharge-specific plasma parameters.

Electron density measurements of atmospheric-pressure non-thermal N2 plasma jet by Stark broadening and irradiance intensity methods

“…By applying the electric field in a wide range, we can obtain three independent curves of the electron densities based on functions (20)- (22) and estimate the electron densities accordingly.…”

“…5 and the corresponding irradiance is also shown on the right axis. By applying functions (20)- (22), the n e distribution in a wide range of electric field E is shown in Fig. 6(a).…”

“…21 Compared to the Stark broadening spectroscopic technique, the second method depends on the absolute emission intensity in lieu of the broadening mechanism and can calculate n e lower than 10 14 /cm 3 . 22,23 In addition, nitrogen exists in air and the emission spectra can be acquired easily from the discharge. 24,25 The discharge current is a function of the electron density and can be also used to determine the plasma parameters.…”

Micro‐plasmoids in self organized filamentary dielectric barrier discharges

“…With these calculated parameters, the measured current density and the nitrogen optical emission we can solve the system of equations (1 and 2) and thereby determine the average electron density. With the argon/air excitation model presented in ref., the average electron density in the first three phases of a HV pulse is (2.7 ± 0.4) · 10 14 cm −3 for the stochastic and (3.7 ± 0.9) · 10 14 cm −3 for the self‐organized DBD mode. These values are slightly lower than the electron density (5 · 10 14 cm −3 ) of the filamentary discharge in the negative HV phase of the argon plasma jet from .…”

Optical characteristics of the filamentary and diffuse modes in surface dielectric barrier discharge

“…It is commonly stated that surface DBD exhibits two discharge modes, namely filamentary discharge and diffuse discharge in the open air. Diffuse discharge, also referred to as homogeneous discharge and atmospheric pressure glow discharge, behaves good uniformity along the dielectric surface [10,11]. The streamer discharges appear at the positive half cycle where a series of short and intense current pulses are observed, whereas diffuse discharges appear during negative half cycle where only a few peaks of current occur.…”