Electric field measurement in the dielectric tube of helium atmospheric pressure plasma jet

Abstract

The results of the electric field measurements in the capillary of the helium plasma jet are presented in this article. Distributions of the electric field for the streamers are determined for different gas flow rates. It is found that electric field strength in front of the ionization wave decreases as it approaches to the exit of the tube. The values obtained under presented experimental conditions are in the range of 5–11 kV/cm. It was found that the increase in gas flow above 1500 SCCM could induce substantial changes in the discharge operation. This is reflected through the formation of the brighter discharge region and appearance of the electric field maxima. Furthermore, using the measured values of the electric field strength in the streamer head, it was possible to estimate electron densities in the streamer channel. Maximal density of 4 × 1011 cm−3 is obtained in the vicinity of the grounded ring electrode. Similar behaviors of the electron density distributions to the distributions of the electric field strength are found under the studied experimental conditions.

On the Electrical and Optical Features of the Plasma Coagulation Controller Low Temperature Atmospheric Plasma Jet

“…If we instead assumed the streamer as a propagating conductor whose front had a finite curvature radius of ≈3 mm, E/N went up to ≈50 Td; hence, the BOLSIG+ simulation was performed in the E/N range between 5 and 50 Td. This range can indeed be reasonable, given that it has been experimentally confirmed, by means of the Stark polarization spectroscopy method, in a helium plasma source analogous to the PCC [31]. Figure 9 shows the ratio of the electron temperature to the ion mass T e /m i for pure helium and neon plasmas, as estimated by BOLSIG+.…”

Plasma-surface interaction: dielectric and metallic targets and their influence on the electric field profile in a kHz AC-driven He plasma jet

“…Exactly like in the previously published studies on the same plasma system [24][25][26], the electric field values were measured using optical emission spectroscopy on a forbidden line of Helium (2 1 P-4 1 F), through the observation of its position in the spectrum with respect to the closest allowed line at 492.19 nm (2 1 P-4 1 D). The method is based on the work of Foster [27] and well described in more recent publications [28][29][30].…”

“…The gas flow speed was 1500 SCCM and all data shows properties of the freely expanding jet. larger in the pulsed jet (electron density for the AC jet has been estimated in [25] but not measured).…”

“…The plume of the pulsed jet is much thinner and several times longer, while the electron densities are 1-2 orders of magnitude . The comparison between the plasma jet configuration used in this work, driven by AC kHz sine voltage at 30 kHz (in red) [24,25], and the same configuration driven by positive voltage pulses at 5 kHz repetition frequency, 6 kV amplitude, 1 µs length and 50 ns risetime (in blue) [15,73]. Electric field profiles are shown as a function of the distance from the exit of the capillary.…”

Production of carbon monoxide from a He/CO2 plasma jet as a new strategy for therapeutic applications

“…[ 12 ] These two reactions are the two main probable production reactions in the He/CO 2 plasma jet, [ 47 ] and require energetic electrons. Sretenović et al [ 48 ] showed that electron density in a streamer head in a capillary of a helium plasma jet, which is our case here, is related to the electric field strength in the streamer head. As the Townsend ionization coefficient depends on the local electric field, the evolution of the electron density can be estimated from this coefficient.…”