Dc Glow Discharge Research Articles

Behavior of plasma parameters under mirror and cusp magnetic fields in DC glow discharge – a numerical study

Abstract The plasma parameters in DC glow discharge can easily be controlled by externally applied magnetic field without disturbing internal / built-in process parameters. Though several works have been carried out to study the influence of the magnetic field at different configurations on the plasma parameters, a complete understanding on the behaviour of the plasma discharge under the mirror and cusp fields could not be achieved. Further studies on the same are needed to improve the efficiency of the DC glow discharge system for existing applications and to find the new applications. In this work, a 2D axis-symmetric non-equilibrium plasma model with drift-diffusion approach is developed to study the characteristics of the plasma in DC glow discharge through various plasma parameters under mirror and cusp fields. The effects of current and position of magnetic coils on electric potential, ionization rate, electron temperature and electron number density are predicted and discussed. The distribution of electron number density at various coil currents and positions under both mirror and cusp fields are presented and the operating conditions favorable for applications in surface modification are suggested.

Correlation between temperature distribution and changes in self-organized luminous pattern in an atmospheric pressure DC glow discharge with sheath gas flow

Abstract The self-organized luminous patterns observed above the anode surface in atmospheric-pressure DC glow discharges were changed by the composition of the gas flow. The patterns were observed not only with liquid anodes but also with metal anodes. Various pattern structures were observed by changing the helium gas flow rate in the core and the ambient oxygen gas flow rate supplied during the discharge. When the pattern formation was observed, the emission spectra and the radial spread of the positive column changed, and the voltage–current characteristic also changed. These results suggest that not only the anode surface but the entire discharge affects the pattern formation. Comparing the results for the liquid and metal anodes, the trends in the pattern formation and voltage–current characteristics were almost identical. The gas temperature in the discharge was also investigated in two different ways, by the laser-induced fluorescence spectroscopy of OH radicals and by Rayleigh scattering, showing in good agreement between both methods. Under the condition where the pattern formed, the gas temperature in the discharge was approximately 2500–3000 K and higher than that of the discharge without the pattern formation. Focusing on the gradient of the temperature distribution, the discharge with the pattern formation had a steeper gradient than that of the discharge without the pattern formation. It is suggested that not only the high temperature of the discharge but also the large gradient of the temperature change plays an important role in the pattern formation. The role of oxygen gas in the pattern formation may be the effect of increasing the temperature and altering the temperature gradient in the discharge rather than generating negative ions in the discharge.

Observation of self-excited oscillations in DC glow discharge dusty plasma

We present a detailed experimental study of discharge current oscillations in a planar cathode plasma with poly dispersed alumina dust particles. Our experimental measurements suggest that surface density of dust particles play an important role together with cathode spots, in deciding self excited oscillating regime or stable dust cloud regime. Experiments conducted with dust particles density below the critical limit shows self excited oscillations. Operating above the critical limit, a dust cloud levitated in the sheath region was observed.

H− production in hydrogen DC glow discharge

The H− ion dynamics in the positive column of H2 DC glow discharge was studied by the laser photodetachment technique in a wide range of pressure, 0.1–3 Torr, and current, 1–30 mA, which cover a range of E/N from ∼40 Td up to ∼170 Td. Using a partial modulation of the discharge current, it is shown that the H−concentration follows H atom dynamics due to a fast detachment reaction with the atoms; the higher the H density, the lower the H–/n e ratio. The dynamics of H atom density during discharge modulation was measured by time-resolved actinometry on Ar atoms, while H2 vibrational temperature was estimated by comparing measured and simulated H2 VUV absorption spectra. The analysis of the experimental dependencies of H− and H/H2 on the discharge parameters allowed estimating the effective rate constant of H− production in the discharge as a function of the reduced electric field. For this discharge model, self-consistent state-to-state vibrational kinetics as well as H2 highly excited electronic states were developed. The main processes that contribute to H− production and loss are discussed in detail. Dissociative attachment to vibrationally excited H2(v) molecules is the main channel of H – production but occurs via the excitation of the well-known low-energy ( ϵ th ≈ 3 eV) shape resonance of H2 −(X2Σu +) only at low E/N. At high E/N, the H– production mostly occurs via the excitation of high-energy H2 − states, such as H2 –(B2Σg +, A2Σg +, C2Πu) and Feshbach resonances similar to H2 −(2Σg +) Rydberg state.

The Effective Capacitance Behaviour of Argon Plasma Exposed Al Dopped CdO Electrode Used in Efficient Metal ‐Air Batteries

AbstractThe impact of employing DC glow discharge plasma on aluminum‐doped cadmium oxide (Al‐doped CdO) electrodes is explored in the context of advanced energy storage, particularly focusing on Al‐air batteries. Utilizing various characterization techniques including XRD, FTIR, Raman spectroscopy, FESEM, and EDS, we identify significant changes in structure and morphology induced by plasma treatment, such as nano scale clustering, increased surface roughness, and higher oxidation levels. Electrochemical tests with a three‐electrode system shows remarkable improvements in charge storage capacity after plasma treatment, particularly with argon plasma, resulting in increased capacitance (1140 Fg−1), specific capacity (681 mAhg−1), and reduced charge transfer resistance (4.2 Ω), with notable changes in behavior, especially in potassium hydroxide (KOH) electrolyte.

Enhanced Physio‐Chemical Properties of PMMA/PS Polymer Blends by DC Glow Discharge Plasma Treated K2TI6O13 for Electronic Applications

AbstractCeramic filler modified polymer blends are more in demand due to their excellent compatibility, easy processing and cost‐effectiveness. In the present work, we modified Polymethyl methacrylate (PMMA)/Polystyrene (PS) blends using solution blending with untreated (UT) and DC glow discharge plasma‐treated (air plasma treated‐APT) potassium hexatitanate (K2Ti6O13). Chemical bonding of virgin and modified blends was confirmed by Fourier transform infrared spectrophotometer (FTIR). Decreased structural defects and imperfections of KTO were confirmed by Raman spectroscopy. Modified surface morphology and elemental analysis were detected by scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDAX). The quantification of particle size distribution has been determined by Zetasizer. Increased degree of crystallinity and decreased average crystallite size after plasma treatment were determined by X‐ray diffraction. Increased dielectric constant from ~22–200 and decreased loss up to 0.7 were analyzed by impedance analyzer. Lee's disc probe was deployed to confirm the optimized thermal conductivity of the modified blend system. By Differential Scanning Calorimetry, glass transition temperature of modified polymer blends was investigated. The change in surface from hydrophobic to hydrophilic by plasma exposure was confirmed by surface goniometer. However, the enhanced dielectric performance of modified PMMA/PS/KTO polymer blends may be suitable for flexible energy storage devices and gadgets.

Solid Phase Synthesis of Cobalt Ferrite Under the Action of a DC Glow Discharge at Atmospheric Pressure

Solid Phase Synthesis of Cobalt Ferrite Under the Action of a DC Glow Discharge at Atmospheric Pressure

Blend of low cost electrode material for energy storage device under DC glow discharge plasma exposed ESAC

Blend of low cost electrode material for energy storage device under DC glow discharge plasma exposed ESAC

Vacancy formation in a 1D chain of dust particles in a DC discharge

The paper presents the first experimental observation of an atypical phenomena during self-organization of dust particles into a one-dimensional chain structure levitated vertically in the plasma of a DC glow discharge. Using a laser, the third (middle) dust particle was removed from the chain of five particles so that the positions of the remaining particles did not significantly change, and a vacancy occurred in the place of the removed particle. This state of the chain turned out to be very stable, which is confirmed by the observation of the subsequent exchange of places of the fourth and the fifth particles of the chain upon the action of the laser on the forth particle. After the exchange process, vertical positions of all particles (first, second, fourth and fifth) in the chain remained almost the same as before the exchange, and the vacancy at the position of the third particle was preserved. The experimental data and the video record of the observed phenomena as well as the estimates of the plasma parameters are presented. An assumption has been made about the mechanism of the discovered phenomena that at present discharge conditions both the vacancy formation and the dust particles positions exchange are possible due to a strong ion wakes which are formed behind the upstream dust particles of the chain.

Assessing the efficacy of an atmospheric air DC glow discharge system for sustainable nitrogen fixation: a vibrational coherent anti-Stokes Raman scattering study

In addressing the substantial greenhouse gas emissions produced by the energy-intensive Haber–Bosch synthesis, this study investigates the viability of sustainable nitrogen fixation (NF) via low-temperature plasma systems energized by renewable sources. Utilizing vibrational coherent anti-Stokes Raman scattering as a diagnostic tool, we probed the nitrogen rovibrational temperature and population dynamics within a DC glow discharge in atmospheric air, a setting with considerable promise for eco-friendly fertilizer production. Besides, density for atomic N , O , and NO was quantified by laser-induced fluorescence (LIF) or two-photon absorbed LIF methods. Our findings reveal a quasi-equilibrium between rotational and vibrational energy states in the DC glow discharge environment, reaching an approximate value of 3500 K at the discharge core. The discharge parameters, discharge current, air flow rate, and discharge gap influence the rovibrational temperature, density distribution of species of interest, and the NF energy cost. However, the influences induced by these parameters are of limitations. Further analysis implies that the high gas temperature and its induced significant vibrational-rotational and vibrational-translational energy exchange are mainly responsible for the non-ideal NF energy cost.

Surface recombination in Pyrex in oxygen DC glow discharges: mesoscopic modelling and comparison with experiments

Surface recombination in an oxygen DC glow discharge in a Pyrex (borosilicate glass) tube is studied via mesoscopic modelling and comparison with measurements of recombination probability. A total of 106 experimental conditions are assessed, with discharge current varying between 10 and 40 mA, pressure values ranging between 0.75 and 10 Torr, and fixed outer wall temperatures ( Tw ) of −20, 5, 25 and 50∘C . The model includes O+O and O+O2 surface recombination reactions and a Tw dependent desorption frequency. The model is validated for all the 106 studied conditions and intends to have predictive capabilities. The analysis of the simulation results highlights that for Tw=−20∘C and Tw=5∘C the dominant recombination mechanisms involve physisorbed oxygen atoms ( OF ) in Langmuir–Hinshelwood (L-H) recombination OF+OF and in Eley–Rideal (E-R) recombination O2+OF , while for Tw=25∘C and Tw=50∘C processes involving chemisorbed oxygen atoms ( OS ) in E-R O+OS and L-H OF+OS also play a relevant role. A discussion is taken on the relevant recombination mechanisms and on ozone wall production, with relevance for higher pressure regimes.

Nitrogen plasma treated cotton fabrics coated with SiO2 followed by RGO deposition for water purification process

Experimental investigations have been carried out to modify the surface properties of Cotton fabrics using low temperature DC glow discharge nitrogen plasma. Plasma treatment is an eco-friendly, dry and clean process over wet chemical methods and does not suffer from any environmental and health concerns [1]. The important plasma parameters such as power and working pressure are kept constant with various treatment times (5, 15, 30, and 60 mins). The plasma-treated cotton fabrics are optimized by XRD, FTIR, and SEM. A comparative study has been done for the untreated and different treated fibers. Pure SiO2 is coated on untreated and nitrogen plasma treated cotton fabrics by sputtering method. The samples are coated for different sputtering times (10 and 30 min). Finally, Reduced Graphene Oxide (RGO) is coated on plasma treated SiO2 deposited fabrics. RGO is prepared by modified hummers methods [2]. Our results provide a way to develop a filter for water purification.

High Porous Activated Carbon Electrode Derived from Watermelon Peel Biomass Exposed with DC Glow Discharge Plasma Applied for Super Capacitors

The growing demand for sustainable and environmentally-friendly technologies has spurred the exploration of innovative methods for waste management and resource utilization. Among the various bio-wastes generated globally, watermelon peel emerges as a significant contributor. To characterize carbon materials in the presence of functional groups, for morphological analysis, and intensity, we subjected activated fruit peel carbon to X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman studies. Furthermore, we examined its electrochemical performance. Another method used to assess wettability is the contact angle. Watermelon-rind-activated carbon was exposed to a DC glow discharge oxygen and air plasma with a 450 V applied potential. The air-treated carbon demonstrated a noteworthy capacitance of 1669 F g−1 at 0.5 mA g−1 in a 2 M KOH electrolyte. Our study found that the properties of the activated carbon were enhanced through cold plasma treatment. This research provides valuable insights into the potential resources of fruit peels and proposes a novel adsorbent with cost-effective advantages in supercapacitors, which could provide effective energy storage for portable gadgets, electric cars, and renewable energy systems, thus presenting a solution for sustainable waste management.

Excellent Diffusive Performance of Cold-Plasma-Exposed Activated Peanut Shell Carbon as an Electrode in Al-Air Batteries

Modern energy and ecological sustainability can be accomplished in part, by using activated bio char-based electrodes made from biomass waste in energy-producing devices like metal-air batteries and fuel cells. Herein, a simple method of combining Pyrolysis graphitization with DC glow discharge plasma is used to create highly disorder carbonaceous materials incorporating surface functional groups from a readily available and inexpensive bio waste of peanut shells. The synthesized activated Peanut shell carbon material displays remarkable supercapacitance performance in 2 M KOH at elevated specific capacitances (537 Fg−1 at 10 mVs−1) and catalytic ability for the oxygen reduction response at a half-wave peak of 0.19 V. Water contact angle and dispersion studies showed a considerable improvement in the surface’s hydrophilic following plasma treatment, and FTIR and Raman spectroscopy were also used to evaluate the surface’s functional group and micro structure. In this study, a simple, affordable, and environmentally friendly method for making activated dis ordered carbon is revealed. It is then investigated as a potential electrode for supercapacitor, metal air battery, fuel cell applications.

Theoretical comparison of effects of different cross fields on low pressure DC glow discharge

the mathematical models of glow discharge in transverse (y-direction) and axial (z-direction) magnetic fields are established in this paper. Firstly, Paschen's law is modified for different cross fields. The results show that the breakdown voltage first decreases and then increases with the increase of y-direction magnetic field at the same pressure. The breakdown voltage of glow discharge in z-direction magnetic field increases with the increase of magnetic field. Secondly, the effects of y-magnetic field and z-magnetic field on glow discharge are compared and analyzed by using the modified ionization coefficient. The results show that the plasma density has an extreme value under the combined action of y-direction magnetic field and air pressure. At the same pressure, the plasma density first increases and then decreases with the increase of magnetic field. The larger the magnetic field, the more obvious the plasma attenuation. In the z-direction magnetic field, the plasma density increases with the increase of air pressure or magnetic field.

Response of the modified GAFCHROMIC EBT2 radiochromic film to DC glow discharge plasma

The response of the modified GAFCHROMIC EBT2 radiochromic film to DC Oxygen glow discharge plasma was investigated using a flatbed scanner and an UV–Vis spectrophotometer. The film was modified by removing the polyester overlaminate, adhesive, and topcoat layers with a total thickness of 80 µm, and is now referred to as EBT2-M. The EBT2-M films were exposed to DC Oxygen plasma for different durations: 0, 0.5, 1, 2, 3, 4, 7, and 10 min. The exposed films exhibit coloration homogeneity with an average variation of (1.6 ± 0.3) × 10−4 pixel values/µm, irrespective of the applied exposure time. The pixel values of the red-and-green channels and weighted grayscale images decreased exponentially with different sensitivity amounts to ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 39.67, 49.69, and 42.11 min−1, respectively, as the exposure time increased. The two absorption peaks at 580 ± 4 nm and 632 ± 4 nm in the UV–Vis absorption spectra of the exposed GAFCHROMIC EBT2-M radiochromic films are increasing with increasing exposure time up to 4 min, thereafter saturated for prolonged exposure time. The integrated absorbance in the range from 400 to 700 nm is linearly correlated with the exposure time. The indirect and direct optical energy band gaps and Urbach energy of the modified GAFCHROMIC EBT2 film are weakly correlated with the exposure time. These findings suggest the utilization of the modified GAFCHROMIC EBT2 radiochromic film as a novel and simple technique for plasma diagnostics.

Numerical Study of the Influence of Pressure on the Dynamics and Complex Bifurcation Processes of the Low-Pressure DC Glow Discharge

Numerical Study of the Influence of Pressure on the Dynamics and Complex Bifurcation Processes of the Low-Pressure DC Glow Discharge

Electric field-assisted laser ablation fabrication and assembly of zinc oxide/carbon nanocomposites into hierarchical structures for supercapacitor electrodes.

One of the major challenges in the field of electrochemical energy storage device performance improvement is the development of suitable synthetic materials for electrodes that can provide high power and high energy density features combined with their long-term stability. Here, we have developed a novel two-step approach based on DC glow discharge plasma pre-treatment of a carbon cloth substrate followed by electric field-assisted laser ablation for the synthesis of ZnO/C nanocomposites in a liquid and their simultaneous assembly into hierarchically organized nanostructures onto the pre-processed carbon cloth to produce a supercapacitor electrode. To form such nanostructures, a processed carbon cloth was included in the electrical circuit as a cathode during laser ablation of zinc in water, while a zinc target served as an anode. A series of studies have been performed to explore the structure, morphology, composition and electrochemical characteristics of the synthesized ZnO/C nanocomposites. Application of the external field provided additional possibilities for tuning the particle morphology. The parameters of the obtained nanostructures were shown to depend on the direction of the applied electric field and liquid composition. SEM studies revealed a nanoflower-like morphology of the prepared nanomaterial having potential in supercapacitor applications due to a large surface area. The ZnO/C nanoflowers, deposited onto a carbon cloth substrate, were tested for energy storage by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) analysis. The results showed a pseudocapacitor behavior with a maximum specific capacitance of about 3045 F g-1 (at a scan rate of 1 mV s-1). These results demonstrate a promising storage efficiency of the synthesized ZnO/C nanocomposite as a material for supercapacitors.

Investigation of the temperature of electrons in a glow discharge plasma at direct current Ar and Ar/C2H2

This paper presents the results of the study of the electron temperature in argon and argon-acetylene plasma of DC glow discharge. The optical-emission method was used to determine the main parameter of the complex plasma. The dependence of the electron temperature on the operating pressure, voltage, and discharge time was determined from the intensity of spectral lines. The source voltage was varied from 1 kV to 1.5 kV, and the pressure was maintained between 0.1-1 torr. As a time-dependent function, the electron temperature was calculated every 20 seconds during a 200-second discharge. The results showed that in argon plasma, as the pressure increases, the electron temperature decreases up to a pressure value of 0.4 torr, subsequent increase leads to an increase in temperature. Also, with the increase in source voltage, a decrease in electron temperature within the error limits is observed. In addition, in dust plasma (PECVD in Ar-C2H2), the electron temperature as a function of pressure and source voltage showed a trend similar to that observed in argon plasma. However, the electron temperature in dust plasma increases as a function of time at the initial moment, after which it decreases sharply with time.

Spectroscopic evaluation of nitrogen glow discharge for the surface nitriding of Ti-6Al-4V alloy

The study investigates the spectral characteristics of a DC glow discharge generated in a parallel electrode configuration for nitriding the Ti-6Al-4V alloy to enhance its surface properties. At first, optical emission spectroscopy (OES) was used to optimize the glow discharge for a certain nitrogen fill pressure and discharge power. The Ti-6Al-4V alloy is then subjected to plasma treatment in an optimized N2-discharge environment. The treated samples' microstructures, surface morphology, elemental composition, and surface roughness are all determined by several material characterization techniques, including XRD, SEM, EDX, and AFM. The Ti-alloy's crystalline phase distribution affects the alloy's physical and chemical characteristics, which determine its suitability for various applications in aerospace and medical implants. A phase shift from Ti(101)α to Ti(110)β is observed owing to the progressive increase in nitrogen interstitials in Ti sites, which promotes the phase transition. The EDX results show that the amount of nitrogen in the spectrum increases, demonstrating that nitrogen has successfully been incorporated into the surfaces of alloys. The surface morphology of the treated samples has improved with longer treatment times, as seen by SEM pictures of samples that have received plasma treatment. Finally, the comparison of the samples' AFM topological measurements and textures at 5, 10, and 15 h demonstrates the importance of treatment time on the development of the Ti-6Al-4V surface roughness and microstructure.