Diffuse and spotted anode layers in an atmospheric pressure glow discharge with a water electrode and miniature argon flow

Abstract

Upon varying discharge current and gap width, several self‐organized patterns are observed in the anode layer of an atmospheric pressure glow discharge with miniature axial argon flow, including diffuse‐disk, single‐ring, disk‐ring, wheel‐spokes, and radial‐stripes patterns. Among them, the wheel‐spokes pattern is observed for the first time in atmospheric pressure glow discharge above a water anode. The conditions for generating the self‐organized patterns are also investigated. Fast photography results indicate that the patterns with low current and narrow gap are diffuse in nature, while those with high current and wide gap are composed of individual spots. This is further verified from waveforms of applied voltage and light emission signals. Moreover, the generation, movement, and disappearance of discrete spots are observed by a high‐speed video camera. Besides, the optical emission spectrum indicates that the glow discharge above the water surface is abundant with electronegative species, including O, NO, NH, and OH. Finally, the formation mechanism of diffuse and spotted anode layers is revealed.

Efficient hydrophilicity improvement of titanium surface by plasma jet in micro-hollow cathode discharge geometry

“…The spectra mainly include the second positive system of N 2 (C 3 Π u →B 3 Π g ), [29][30][31]48,49] where the dominant emission band heads at 337.1 nm, the first positive system of N 2 (B 3 ∏ g → A 3 ∑ + u ), [50][51][52] the first negative system of N + 2 (B 2 ∑ + g −X 2 ∑ + g ), [32,53,54] and OH transition (A 2 Σ + →X 2 Π). [33,55,56] Furthermore, the spectral line of O I (3p 5 P→3s 5 S) can also be discerned at 777.4 nm. [44] Hence, one can deduce that the active species in the plasma include electrons, positive ions (N +…”

Discharge aspects of a snake‐like plasma plume generated by an atmospheric pressure plasma jet with variable argon flow rate

“…For the snake-like plume, the length dependence can be explained by the same reason reported by Xian et al [75] Let us consider the dark plasma channel behind the streamer head, in which negative oxygen ions are formed due to electron attachment. [76][77][78] With increasing Q, fewer electrons are attached due to C O decrease, resulting in a higher conductivity of the plasma channel and a lower potential drop along the channel. Therefore, the potential drop of the streamer head increases, which will direct the streamer to propagate a longer distance.…”

Spatio-temporal evolution characteristics and pattern formation of a gas–liquid interfacial AC current argon discharge plasma with a deionized water electrode

“…Atmospheric gas-phase discharges can be operated with a large gap spacing over the liquid electrolyte surface. Various self-organized emission patterns have also been formed using an electrolyte anode [8][9][10][11][12]. The formation of discharge emission patterns over the liquid surface is a crucial phenomenon that must be studied in order to explore the discharge operating mechanisms that are relevant when the liquid is an electrode.…”

“…Formation of ring-like, double ring-like, cone-shaped, and other patterns from AC-and DC-driven discharges over the liquid (deionized water (DIW) or tap water or electrolyte solution) surface has been examined by increasing current magnitudes and discharge power levels just after discharge initiation [8][9][10][11][12]. In atmospheric pressure plasma generated by an AC power supply, self-organized patterns such as ringlike, plasma-spot etc were observed over the liquid-electrode (tap water (500 μS cm −1 ) or DIW (0.055 μS cm −1 )) surface by varying experimental parameters such as power, gap spacing and liquid properties of the electrode [11].…”

“…In atmospheric pressure plasma generated by an AC power supply, self-organized patterns such as ringlike, plasma-spot etc were observed over the liquid-electrode (tap water (500 μS cm −1 ) or DIW (0.055 μS cm −1 )) surface by varying experimental parameters such as power, gap spacing and liquid properties of the electrode [11]. Selforganized patterns such as diffuse disk, single ring etc above the tap water (400 μS cm −1 ) anode were witnessed as a function of gap spacing and discharge current of an argon atmospheric pressure glow discharge driven by a DC power supply [12]. Filamentary streamers from direct-in-liquid discharges excited using DC power have been observed in liquids (DIW and solution) [17].…”