Optical and electrical characterization of a surface dielectric barrier discharge plasma actuator

Abstract

An experimental characterization of the properties of asymmetric surface dielectric barrier discharges used as plasma actuators was performed. Optical emission spectroscopy was used to measure the radiated power and some plasma parameters such as the electron and vibrational temperature. Electrical characterization of the discharge was executed by recording individual current pulses with high temporal resolution, and collecting a large dataset of these events. Statistical analysis performed on them allowed one to correlate microdischarge (MD) properties with the voltage phase and to spot differences arising from the actual breakdown mechanism in such asymmetric configurations. In particular, the asymmetry between the two different half-cycles of the discharges was characterized, and it was found that it directly influences plasma actuator efficiency. Differences arising in the multiplicity, amplitude and temporal duration of the MDs were investigated. Some effects connected with the dielectric material and high voltage supply properties were evaluated and correlated with the induced velocity provided by the plasma actuators.

Spatial and temporal evolution of microdischarges in Surface Dielectric Barrier Discharges for aeronautical applications plasmas

“…10 8 m/s, corresponding to a refractive index of 1.56±0.01. This refers to the near UV region, since the DBD emission spectra are dominated by the nitrogen second positive system, which matches quite well the 300-500 nm peak sensitivity of the PMT [9,10]. By inverting the delay length of the two viewlines we could also confirm that no bias in the delay was introduced.…”

“…A current transducer like a Rogowski coil is suitable to measure electric current filaments. As already discussed in a dedicated paper [8], we were able to study current pulses characteristics like number, amplitude, duration and charge transported [9]. A capacitance in series with the electrode setup have been used too in order to measure the effective power absorbed by the microdischarges as well as the total charge accumulated on the dielectric surface [9].…”

“…Here we are primarily concerned with the light emitted from the discharge. We have already reported about the measured emission spectra of the discharges in a spectral band extending from 200 to 850 nm by means of a wide band, low resolution spectrometer (PS2000 by Ocean Optics) [9]. Spectra are typical of DBD, with the brightest feature being the 2 nd positive system of nitrogen, emitted from the N 2 (C) excited level of the molecule.…”

“…There are several tricky aspects, including the geometry of the electrodes and the charging of the dielectric material surface facing the discharge region. In particular the asymmetry in the two portions of the discharge is considered to be essential in the production of the so called ionic wind [7][8][9].…”

Tomography of a simply magnetized toroidal plasma

“…Moreover, the same approach used for the H α emission line could be easily adopted to reconstruct the poloidal profile of each emission structure in the spectra. Whereupon the comparison of the intensity of different emission lines could be used to gain insight into related plasma parameters, including the electron temperature [22], vibrational temperature [18], distribution of impurities, dissociation degree, by comparing atomic and molecular hydrogen emission lines [24] or the neutral gas temperature, by inspecting the rotational structure of molecular emission lines [25]. Absolute intensities are however needed if electron density is to be measured [10,22].…”