Time and spatial resolved optical and electrical characteristics of continuous and time modulated RF plasmas in contact with conductive and dielectric substrates

Abstract

Cold atmospheric pressure plasma jets are often used as a remote plasma source for substrate treatments. However, this substrate acts as an electrode and this additional electrode can induce effects on plasma parameters such as the dissipated power, gas temperature, etc. In this work the influence of substrates of different conductivity and permittivity in direct contact with three different operational modes of atmospheric pressure RF plasma jets is investigated. Two different electrode configurations (creating either a linear or a cross electric field) and, for the linear field configuration, two voltage modulations (continuous RF and kHz pulsed RF) have been studied. Electrical and optical diagnostic methods have been performed in order to get quantitative data of the change in plasma dissipated power and gas temperature, when the plasma is in direct contact with the substrate. In all three investigated cases the power dissipation and gas temperature, significantly increase when the plasma is in direct contact with a conductive substrate. The increase of power is attributed to a change of the equivalent electrical circuit, leading to a more favourable matching between the power input and the plasma source.

Numerical analysis of the effect of nitrogen and oxygen admixtures on the chemistry of an argon plasma jet operating at atmospheric pressure

“…These values of dissipated power are in agreement with the power reported by other groups using similar argon RF atmospheric pressure plasma jets, i.e. with similar length and gas temperatures, geometry, gas flow rate, etc [24,34].…”

Distinct modes in the evolution of interaction between polymer film and atmospheric pressure plasma jet

“…Once a point is completely etched on the polymer film, the electric field in the channel between the high voltage electrode and sample is significantly reinforced. This might be attributed to the change of Z sample , which leads to a more favorable matching between the power input, the plasma configuration and the sample . As a result, the plasma is coupled to the substrate and concentrated in the etched hole and removes the film simultaneously in the radial direction with a center point.…”

“…Moreover, the difference of samples’ conductivity and permittivity will also influence the electric circuit and thereby alter the discharge and plasma characteristics . With a conductive or semiconductive substrate, the current RMS value, dissipated power and luminous intensity of APPJ increases.…”

“…Different surface materials treated by APPJ have been investigated by many researchers, including conductive materials, semi‐conductive materials, and dielectric materials . The influence of substrates with different conductivity and permittivity in direct contact with an atmospheric pressure RF plasma jet had been investigated by Hofmann et al Compared to dielectric substrates, they found that conductive substrate significantly influence the plasma parameters such as dissipated power, gas temperature, etc. They also pointed out that the substrates actually acted as an additional electrode, which could induce effects on plasma characteristics .…”

“…The influence of substrates with different conductivity and permittivity in direct contact with an atmospheric pressure RF plasma jet had been investigated by Hofmann et al Compared to dielectric substrates, they found that conductive substrate significantly influence the plasma parameters such as dissipated power, gas temperature, etc. They also pointed out that the substrates actually acted as an additional electrode, which could induce effects on plasma characteristics . Norberg et al carried out a computational investigation of the interaction of an APPJ with the materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet .…”