Discharge phenomena of an atmospheric pressure radio-frequency capacitive plasma source

Abstract

Discharge phenomena of a nonthermal atmospheric pressure plasma source have been studied. An atmospheric pressure plasma jet (APPJ) operates using rf power and produces a stable homogeneous discharge at atmospheric pressure. After breakdown, the APPJ operation is divided into two regimes, a “normal” operating mode when the discharge is stable and homogeneous, and a “failure” mode when the discharge converts into a filamentary arc. Current and voltage (I–V) characteristics and spatially resolved emission intensity profiles have been measured during the normal operating mode. These measurements show that the APPJ produces an alpha (α) mode rf capacitive discharge. Based upon a dimensional analysis using the observed I–V characteristics, a rough estimate is made for plasma density of 3×1011 cm−3 and an electron temperature of 2 eV. In addition, the gas temperature of 120 °C has been spectroscopically measured inside the discharge. These plasma parameters indicate that the APPJ shows promise for various materials applications as it can produce substantial amounts of reactive species and avoid thermal damages, while having the advantage of atmospheric pressure operation.

Mode Characteristics of radio-frequency atmospheric glow discharges

“…In the mode, the gap voltage increases monotonically with the discharge current density and the differential conductivity of the discharge is positive. This trend is identical to that of available RF APGD experiment data [1]- [9], [16] and also consistent with the mode in low-pressure glow discharges [17], [18]. As the current density increases above 28 , the gap voltage increases less for a given increment in the discharge current.…”

“…At lowcurrent densities, the discharge current increases in proportion to the RF voltage across the electrode gap and the differential conductivity of the plasma is positive. This is similar to the mode in low-pressure glow discharges, and corresponds to the operation regime of most reported RF APGD experiments [1]- [7], [9], [16]. When the current density increases to a critical threshold, the discharge plasma evolves into a different operation regime in which the discharge current increases with decreasing gap voltage and the differential conductivity becomes negative [8].…”

“…The current-voltage relationship of Fig. 2 for the and modes in RF APGD are very similar to that observed for RF APGD [4], [5], [8], [9], [16], and also for low-pressure glow discharges [17]- [19]. We will revisit the above discussion in the next section where the electric field and the electron energy are profiled for both the mode and the mode.…”

Absolute atomic oxygen density measurements by two-photon absorption laser-induced fluorescence spectroscopy in an RF-excited atmospheric pressure plasma jet

“…Earlier investigations of the discharge characteristics of the APPJ include optical emission spectroscopy (OES), Langmuir probes and electrical measurements [4][5][6][7]. The results can be summarized as follows: the APPJ is an α-mode capacitive RF discharge with a gas temperature below 200˚C, electron densities from 10 11 to 10 12 cm −3 and a mean electron energy of ∼2 eV.…”

Studying The Effect of Cold Plasma on Living Tissues Using Images Texture analysis

“…Non-thermal plasma which is so co-called plasma needle which is produced under atmospheric pressure by resources of radio-frequency excitation has been studied to reach the optimal aim of the paper which treating the fine surface of (bio) materials [17,18]. The needle plasma is generated by nitrogen, argon, helium, and mixtures of He with air.…”