The effects of grounded electrode geometry on RF-driven cold atmospheric pressure plasma micro-jet
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RESEARCH
The effects of grounded electrode geometry on RF‑driven cold atmospheric pressure plasma micro‑jet Davood Hassanpour1 · Sayyed‑Jalal Pestehe1 Received: 18 January 2020 / Accepted: 17 September 2020 © Islamic Azad University 2020
Abstract With the argument that two-electrode DBD-like systems are much more operational than single-electrode systems in biomedical applications, targets sensitive to temperature and electric shock, the effects of parameters associated with the geometry of the grounded electrode such as its shape, size, and position it at the output of the atmospheric pressure RF plasma jet in two-electrode systems is investigated. By varying the position of the typical narrow ring grounded electrode on the dielectric tube toward the powered electrode, the ratio of the axial to radial electric field components depend on the externally applied potential to the plasma has been investigated and shown that the axial component of the electric field is maximized at certain position(s) of the grounded electrode. The analysis of the data indicates that there is an inverse relationship between the magnitude of the axial electric field in the plasma channel and the discharge ignition voltage, and a direct relationship with the plasma jet length. It is known that by increasing the width of the ground electrode until the full covering of dielectric, the jet length increases from the dielectric output to the neighborhood near the needle electrode, and reduces the discharge ignition threshold and consequently power consumption of the jet, but increasing its width to greater than the above values does not have a significant effect on jet output. It has also been shown that by tapering the dielectric end and fully covering it with its conical-shaped electrode, the output jet length increases and decreases its width. Keywords Atmospheric pressure plasma jet · DBD-like · Grounded electrode geometry · Jet length · Electrode shape
Introduction The various types of atmospheric pressure plasma jets with different structures have been reported in which they use inert gases or combine inert gases with reactive gases such as O2 [1, 2]. Among different structures, the DBD-like structures include a powered needle electrode associated with a grounded electrode (usually ring-shaped) and single-electrode structures consist of a single powered needle or ring electrode in the absence of the grounded electrode, have operational benefits for working with radio-frequency (RF) power supplies. Figure 1 shows a schematic of these two structures.
* Sayyed‑Jalal Pestehe [email protected] Davood Hassanpour [email protected] 1
Advanced Plasma Laboratory, Faculty of Physics, University of Tabriz, Tabriz, Iran
As the working gas flows, such as He or Ar, through the dielectric cylinder, the gas is ionized in the vicinity of the needle electrode and a glow plasma plume exits in the downstream known as a plasma jet. These types of plasmas operate at atmospheric pressure and are classified into two major groups of cold and hot atmo
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