Electrical Features of Radio-frequency, Atmospheric-pressure, Bare-metallic-electrode Glow Discharges

Abstract

Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas with bare metallic electrodes have promising prospects in the fields of plasma-aided etching, deposition, disinfection and sterilization, etc. In this paper, an induced gas discharge approach is proposed for obtaining the RF, atmospheric-pressure, c-mode, glow discharges with pure nitrogen or air as the primary plasma-working gas using bare metallic electrodes. The discharge characteristics, including the discharge mode, the breakdown voltage and discharge voltage for sustaining a mode and/or c mode discharges, of the RF APGD plasmas of helium, argon, nitrogen, air or their mixtures using a planar-type plasma generator are presented in this study. The uniformity (no filaments) of the discharges is confirmed by the images taken by an iCCD with a short exposure time (10 ns). The effects of different gap spacings and electrode materials on the discharge characteristics, the variations of the sheath thickness and the electron number density are also studied in this paper.

A salt tolerant Enterobacter cloacae mutant for bioaugmentation of petroleum- and salt-contaminated soil

“…Mutation of E. cloacae using pure helium plasma jet was carried out in the radio frequency (RF) atmospheric pressure glow discharge (APGD) plasma system, which consisted of an RF (13.56 MHz) power supply, co-axial type plasma generator, gas supply, and a sample plate made of stainless steel [20][21][22]. The operational parameters were as follows [23]: the RF power input was 120 W; distance between the plasma torch nozzle exit and sample plate, 2 mm; and temperature of the plasma, below 40 • C. The original strain was cultivated in LB medium on a shaker at 30 • C and 150 rpm for 9 h. The OD 600 value of the culture solution was adjusted to 1.0 with sterile 50 mM PBS buffer (pH 7.0).…”

Atmospheric glow discharges from the high-frequency to very high-frequency bands

“…Compared to low-pressure discharges, homogeneous APGDs are much more susceptible to rapid transition into a constricted ␥ mode when excited in the common high-frequency ͑HF͒ band of 3-30 MHz. [5][6][7][8][9] By reducing the input rf power, it is possible to operate in the more stable ␣ mode but at the expense of low electron densities thus compromising their application efficiency. 10 One technique to achieve high plasma density without plasma constriction is to add a dielectric barrier to the electrodes so as to control the growth of the discharge current.…”

“…It is known that with sufficient input power the sheath region could undergo an abrupt collapse thus causing the discharge to enter the less stable ␥ mode. [5][6][7][8][9] In the 20 MHz case, point a marks the ␣ − ␥ mode transition beyond which increasing input rf power was found to constrict the discharge into a bright plasma column typically less than 1 mm in diameter. In the 40 and 60 MHz cases, points b and c indicate plasma conditions under which the discharge became radially inhomogeneous, consisting of an optically intense channel surrounded by a weak but expansive and diffuse region.…”

Study on atmospheric air glow discharge plasma generation based on multiple potentials and aramid fabric surface modification

“…However, when using these gap discharge structures to treat materials, the electrodes are located on both sides of the materials. The dielectric properties and size of the materials themselves lead to changes in partial discharge characteristics, which increases the possibility of discharge transforming into the filamentous form …”