Pressure Plasma Jet Research Articles

One step coating anti-reflective SiO2 film for silicon solar cells applications by atmospheric pressure plasma jet

By utilizing an atmospheric pressure plasma jet, a one-step deposition of anti-reflective silicon dioxide coating was successfully achieved on solar cover glass. A two-dimensional moving platform was utilized to coat large-area cover glass measuring 300 mm * 300 mm. Remarkably, at an input power of 40 W, the temperature of the cover glass remained as low as 59.4 °C. The impact of different motion patterns on the anti-reflective properties of the film was thoroughly investigated. Upon assembling the solar cells, a notable efficiency enhancement from 24.03% to 24.28% was observed. This method demonstrates promising prospects for repairing anti-reflective films on malfunctioning solar cell modules in photovoltaic power plants.

Modification of Silicon Nanostructures by Cold Atmospheric Pressure Plasma Jets

Cold atmospheric plasma (CAP) jets with helium (He) and argon (Ar) plasma-forming gases were used to modify the structure, photoluminescence (PL), and electrical properties of arrays of silicon nanowires (SiNWs) with initial cross-section sizes of the order of 100 nm and length of about 7‒8 microns. The CAP source consisted of a 30 kHz voltage generator with a full power up to 5 W and the CAP treatment for 1‒5 min resulted in spattering of SiNWs’ tips followed by redeposition of silicon atoms. An increase of the silicon oxide phase and a decrease of the PL intensity were observed in the plasma processed SiNW arrays. A decrease of the free hole concentration and an increase in the free electron density were revealed in heavily boron and phosphorous doped SiNWs, respectively, as it was monitored by means of the Raman spectroscopy, considering a coupling of the light scattering by phonon and free charge carriers (Fano effect) in SiNWs. The obtained results demonstrate that the CAP treatment can be used to change the length, sharpness, luminescence intensity, and electrical properties of silicon nanowires for possible applications in optoelectronics and sensorics.

Compared discharge characteristics and film modifications of atmospheric pressure plasma jets with two different electrode geometries

Atmospheric pressure plasma jet shows great potential for polymer film processing. The electrode geometry is the key factor to determine discharge characteristics and film modification of jets. In this paper, we compared the discharge characteristics and the film modifications of atmospheric pressure plasma jets with needle-ring electrode (NRE) and double-ring electrode (DRE). The results show that jet with NRE has stronger electric field intensity and higher discharge power, making it present more reactive oxygen particles and higher electron temperature, but its discharge stability is insufficient. In contrast, the jet with DRE has uniform electric field distribution of lower field intensity, which allows it to maintain stable discharge over a wide range of applied voltages. Besides, the modification results show that the treatment efficiency of PET film by NRE is higher than that by DRE. These results provide a suitable atmospheric pressure plasma jets device selection scheme for polymer film processing process.

The localised density of H2O2 in the effluent of a cold atmospheric pressure plasma jet determined by continuous-wave cavity ring-down spectroscopy

Although the research on cold atmospheric pressure plasma jets and their applications is steadily growing, several questions remain open regarding fundamental aspects of how reactive species, such as hydrogen peroxide (H2O2), are generated in cold atmospheric pressure plasma jets, and how the composition of reactive species can be tailored for a specific purpose. Accordingly, absolute and spatially resolved distributions of the densities of reactive species in the effluent of cold atmospheric pressure plasma jets are required. In this work, a time efficient way to determine the local distribution of gas phase H2O2 in the effluent of a cold atmospheric-pressure plasma jet using continuous-wave cavity ring-down spectroscopy at a wavelength of 8.12 μm is presented. By a combination of an axial scan and of several radial distributions, the localised density distribution of H2O2 in the effluent of the kINPen-sci plasma jet was obtained. Therefore, the effective absorption length was determined from the evolution of the radial distributions as a function of the distance from the nozzle, which was 1.6 mm close to the nozzle of the plasma jet, and increased to approximately 5 mm at a distance of 10 mm from the nozzle. The maximum density of approximately 2 ⋅ 1014 cm−3 was found in the centre of the effluent close to the nozzle. From the presented localised density distribution, it can be concluded that H2O2 is significantly generated within the plasma zone of the plasma jet. This work presents an important step towards the understanding of formation and consumption mechanisms of biomedically relevant species in the plasma zone and the effluent of a cold atmospheric pressure plasma jet.

Comparing efficiencies of polypropylene treatment by atmospheric pressure plasma jets

AbstractPlasma treatment of polypropylene (PP) is a well‐established method of improving its surface properties. However, the efficiencies of different plasma discharges are seldom compared. Herein, we discuss the differences in PP treated by three arc‐based commercial plasma jets working in dry air, Plasmatreat rotating plasma jet (PT‐RPJ), AFS PlasmaJet® (AFS‐PJ), and SurfaceTreat gliding arc jet (ST‐GA), and by the low‐temperature RF plasma slit jet (RF‐PSJ) working in argon. The AFS‐PJ has a significantly different reactive species composition dominated by nitrogen oxides. It induced higher thermal loads leading to surface damage. The other arc‐based jets (PT‐RPJ and ST‐GA) created the PP surface with higher oxygen and nitrogen concentration than the low‐temperature RF‐PSJ. It induced a higher adhesion strength measured on PP‐aluminum joints.

Tuning lattice defects and photocurrent response of ZnO thin films by Mg doping and Ar-H2 atmospheric plasma treatment

The effects of Mg doping and Ar-H2 atmospheric pressure plasma jet (APPJ) treatment on zinc oxide (ZnO) thin films were investigated. Mg doping has been demonstrated to facilitate the incorporation of atomic hydrogen in the ZnO lattice via Ar-H2 APPJ. The co-doping of Mg and H changed ZnO’s primary oxygen defect type from vacancy (VO) to interstitial (Oi), which reduced photocorrosion significantly. The dominance of interstitial defects (i.e., Zni and Oi) in the H-doped Zn0.9Mg0.1O thin film was confirmed by photoluminescence spectroscopy. Zni shallow donors improved light absorption at wavelengths > 650 nm, increasing the film’s photocurrent density. Without Mg, doping H via Ar-H2 APPJ was ineffective for pure ZnO thin film. The dominance of VO in pure ZnO thin film after APPJ, though enhanced light absorbance, gave rise to an erratic photocurrent response due to the instability of VO. The lack of acceptor states also led to severe photocorrosion.

Effect of an additional floating electrode on radio frequency cross-field atmospheric pressure plasma jet

Atmospheric pressure plasma jets with cross-field electrode configuration are a potential jet design for gases with high breakdown fields. This study focuses on the effect of an additional floating electrode on the cross-field plasma jet properties. Detailed experiments are done with the additional floating electrodes of different widths introduced below the ground electrode in a plasma jet with a cross-field electrode configuration. It is observed that in the presence of an additional floating electrode in the jet propagation path, less applied power is needed for the plasma jet to cross the nozzle and jet length increases. This threshold power, as well as the maximum jet length, depends on the electrode widths. A detailed analysis of charge dynamics in the presence of an additional floating electrode shows decrement in the net charge transferred radially to the external circuit through the ground electrode, and an increment in the net charge transferred axially. Increment in the optical emission intensity of reactive oxygen and nitrogen species, as well as the relative yield of ions like N^{+}, O^{+}, OH^{+}, NO^{+}, O^{-}, and OH^{-} in the plasma plume, that are crucial for biomedical applications suggest an improvement in the reactivity of plasma plume in the presence of additional floating electrode.

In situ measurement of dynamic surface charge on dielectrics interacted with plasma jet arrays

As a flexible tool to generate large-scale non-thermal plasma in ambient air, plasma jet arrays have attracted academic attention from multiple fields of biomedicine and material surface sciences. Optimization of plasma processing that heavily relies on trial-and-error experiments requires quantitative in situ diagnostics of plasma–surface interaction. This study focuses on the fundamental surface charge evolution in quartz dielectric deposited by plasma jet arrays. The thin quartz plate is attached to an electro-optic BSO crystal that is conductive and grounded in the back. These jet arrays are driven by a positive microsecond pulsed voltage with kHz frequency. Special attention is paid to the properties and mechanisms of the intriguing convergence of multiple adjacent surface charge patterns. The measured 1D and 2D jet arrays verify the trend of homopolar charge fusion at the plasma–surface interface, which was initially thought to be repulsive under electrostatic forces. The fusion of surface charges is considerably enhanced when more charges are transported onto targeted dielectrics, as well as at smaller separations. The simulation results reveal the mechanism of charge fusion that occurs when surface ionization waves (IWs) are in close proximity, and the high electric field between their heads provides a cluster of high-energy electrons that forces two IWs to merge until they connect. In the case of extremely small separations, the close-in IWs directly merge in bulk before touching the target. Quantitative in situ measurements of surface charges and the corresponding simulations provide fresh insight into the electrical interaction in large-scale atmospheric-pressure plasma jets. The properties of charge fusion can help with manufacturing and optimizing large-area uniform plasma jet sources for various dielectric materials.

Atmospheric Cold Plasma: A Brief Journey and Therapeutic Applications from Wound Healing to Cancer Biology

Cold Atmospheric Plasma (CAP) has now become a well-known new edge technology in the field of biomedical science to agriculture and food technology. Ionized gas known as cold atmospheric plasma has recently been the subject of intense inquiry by scientists for its potential application for treatment in oncology and dentistry. Air, Helium, Argon, Nitrogen, and other gases can all be used to create Cold Atmospheric Plasma. Cold plasma can effectively and safely inactivate spores, bacteria, fungi, viruses, and small molecules and thereby improving wound healing, combating microbial infections, and treating skin conditions with great efficiency. Interestingly the in vitro and in vivo demonstration of CAP has shown promising applications in cancer healing and treatment. The most widely employed technique for producing and sustaining a low-temperature plasma for use in technological and scientific applications involves applying an electric field to a neutral gas. The non-equilibrium atmospheric pressure plasma jet (NAPPJ) and the dielectric barrier discharge (DBD) have both been widely used in biomedical applications. This review aims to evaluate the emerging plasma technology - the basic science, technical aspects and provide insights of biomedical application in diverse area.

Optical emission spectroscopy of an industrial thermal atmospheric pressure plasma jet: Parametric study of electron temperature

The plasma parameters of an industrial atmospheric pressure plasma jet (APPJ) are measured as a function of the electric power of the plasma generator, the gas flow, and the distance from the jet nozzle exit. The APPJ device operates an electric discharge under Argon gas flow resulting into a continuous Argon plasma jet in the kW power range expanding into ambient air. The plasma temperature Te and electron number density Ne are determined by optical emission spectroscopy (OES) analyzing up to 17 emission lines of neutral Ar (I) and singly-ionized Ar (II) species using the Saha-Boltzmann plot (SBP) method. For the accurate determination of plasma parameters a methodology is developed to overcome fundamental limitations in OES of Argon plasma that is due to the strongly different intensities of Ar (I) and Ar (II) emission lines. The most significant step is the use of spectral bandpass filters in the optical collection system. The experimental parameters of the jet device are playing a crucial role for APPJ applications (e.g. thermal load to the workpiece, plasma chemistry interaction etc.). We measure Te and Ne in dependence of the experimental parameters and obtain consistent and accurate values of Te = 9000 ± 150 K and Ne = 5 × 1015 cm−3 (typ.). For comparison, plasma characterization using only the neutral Ar lines gives inaccurate and inconsistent Te values. This highlights the importance of using also the ionic Ar lines. The developed methodology may be diversified and applied also for OES of other rare gas plasma.

Preliminary exploration of the electrical insulation performance of APPJ SiO2 coating on 304 stainless steel pipes

The atmospheric pressure plasma jet (APPJ) technique is used to prepare SiO2 insulation coatings onto the outer surface of 304 stainless steel pipes (304-SSPs). The diameter and surface roughness of 304-SSPs increase from 18 to 32 mm and 0.1 to 1.0 μm. The results show that APPJ scanning methods have little influence on the chemical composition, chemical bond structure, crystal structure, and surface morphology of SiO2 coatings, which display Si/O = 1/(1.95 ± 0.02), dominant Si-O bond, amorphous structure, and dense layer structure. However, APPJ scanning methods have obvious influence on the uniformity and electrical insulation resistance (REI) of SiO2 coatings. Only when APPJ is parallel to the normal direction of 304-SSPs outer surface, the balance between APPJ impingement, gravity, and coating surface tension could reach the optimal condition, which improves the uniformity and REI of SiO2 coatings. With the optimal scanning method, REI of SiO2 coatings decrease with the increase of surface roughness of 304-SSPs, which are caused by the decrease of effective thickness of SiO2 coatings. Most importantly, with the other parameters as constant, REI of SiO2 coatings reaches to ∼101 MΩ and displays the better uniformity when the diameter of 304-SSPs is about 5 times the diameter of APPJ tube.

Facile and versatile fabrication process for AgNW/GZO transparent composite electrodes for photovoltaic applications by atmospheric pressure plasma jet

Transparent conductive oxide (TCO) must have high electrical conductivity and optical transmittance. Using higher doping concentrations improves the conductivity but often at the expense of transmittance in the near-infrared regime. Using thicker film to improve the conductivity is not preferable as it significantly reduces the transmittance. Silver nanowire (AgNW)/ TCO composite film has been proposed as a viable method to address this dilemma. However, AgNWs often require additional thermal treatment to weld the nanowires to reduce the contact resistance. Also, thermal treatment apparatus, such as lasers, cannot be easily integrated into the TCO deposition setup, adding extra cost for handling samples. Here we use an atmospheric pressure plasma jet (APPJ) to fabricate AgNW/ TCO composite films—APPJ successfully welds the AgNWs and covers them with a thin gallium-doped ZnO or GZO protective layer simultaneously. The AgNW weight significantly affects the optoelectronic and morphological properties and can be tailored to fit the requirements of particular photovoltaic applications. Our perovskite solar cells with the AgNW/GZO front electrodes exhibit a ∼21% increase in power conversion efficiency. Furthermore, unlike conventional methods, our approach is vacuum-free and does not require additional processes, such as lasers, to treat the AgNW network, which may greatly reduce operational complexity.

Development of an experimental system for cell viability assays of yeasts using gas-temperature controllable plasma jets

The characteristics of a gas-temperature-controllable atmospheric-pressure helium plasma jet and the development of an experimental system for cell viability assays of yeasts (fission yeast Schizosaccharomyces pombe and budding yeast Saccharomyces cerevisiae) are reported. The physicochemical properties of the plasma plume, which can maintain the temperature of the irradiated object at a temperature suitable for yeast, were not significantly different from those of a typical helium plasma jet. Furthermore, good reproducibility of cell viability was observed when gas temperature, gas flow rate, applied high voltage, and irradiation distance remained fixed, and only irradiation time was used as a parameter. This experimental system allows us to carry out various experiments, such as the search for plasma-resistant mutants that will contribute to the identification of genes involved in resistance to direct plasma irradiation.

Nonthermal atmospheric pressure plasma jet-assisted formation of oxygen vacancies stabilized tetragonal zirconia particles

This study presented a controlled oxygen vacancy formation on stabilization of tetragonal zirconia particles via a nonthermal atmospheric pressure plasma jet (APPJ) with varying the supplied power. The characteristic analyses based on X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy (HR-TEM), Raman, ultraviolet–visible spectroscopy, and ultraviolet photoemission spectroscopy confirm the existence of oxygen vacancies in tetragonal zirconia particles. Production of oxygen vacancies in the prepared zirconia powder is related to the presence of surface defects by observing HR-TEM and further decreases the bandgap as indicated by optical characterization. Thus, it can be anticipated that the research of defect engineering is a promising way to improve the optoelectronic and photocatalytic performance of oxide material via the APPJ method.

Argon Plasma Jet-Treated Poly (Vinyl Alcohol)/Chitosan and PEG 400 Plus Mangifera indica Leaf Extract for Electrospun Nanofiber Membranes: In Vitro Study.

The wound-healing process can be disrupted at any stage due to various internal and external factors. The inflammatory stage of the process plays a vital role in determining the outcome of the wound. Prolonged inflammation due to bacterial infection can lead to tissue damage, slow healing, and complications. Wound dressings made using materials such as poly (vinyl alcohol) (PVA), chitosan (CS), and poly (ethylene glycol) (PEG) with Mangifera extract (ME) added can help reduce infection and inflammation, creating a conducive environment for faster healing. However, creating the electrospun membrane is challenging due to balancing various forces such as rheological behavior, conductivity, and surface tension. To improve the electrospinnability of the polymer solution, an atmospheric pressure plasma jet can induce chemistry in the solution and increase the polarity of the solvent. Thus, this research aims to investigate the effect of plasma treatment on PVA, CS, and PEG polymer solutions and fabricate ME wound dressing via electrospinning. The results indicated that increasing plasma treatment time increased the viscosity of the polymer solution, from 269 mPa∙to 331 mPa∙s after 60 min, and led to an increase in conductivity from 298 mS/cm to 330 mS/cm and an increase in nanofiber diameter from 90 ± 40 nm to 109 ± 49 nm. Incorporating 1% mangiferin extract into an electrospun nanofiber membrane has been found to increase the inhibition rates of Escherichia coli and Staphylococcus aureus by 29.2% and 61.2%, respectively. Additionally, the fiber diameter decreases when compared with the electrospun nanofiber membrane without ME. Our findings demonstrate that electrospun nanofiber membrane with ME has anti-infective properties and can promote faster wound healing.

Long and flexible atmospheric pressure plasma jet probes for operation in humid environments

Herein, we describe a new flexible atmospheric pressure plasma jet device composed of hollow-core optical fibers and introduce two potential applications of the device: endoscopic plasma treatment and decomposition of aqueous phosphorus compounds. The proposed device is 1.6 m long and highly flexible, has a small probe size of several hundred micrometers, and spatially separates the plasma jet from the electrical input, making it very suitable for treatment through the biopsy channel of a conventional endoscope. Because the wire electrode of the fabricated atmospheric pressure plasma jet device is thoroughly isolated inside the hollow of the optical fiber, the device produces a plasma column in an identical discharge state regardless of external environmental conditions. As a result, the device can operate safely and steadily in highly humid environments, such as underwater, which can be utilized to decompose phosphorus compounds in fresh water.

Numerical simulation on the behavior of a negative streamer encountered with a cloud of positive ions in atmospheric pressure plasma jet

Plasma jet normally operates in a regime of positive or negative streamers. Different propagating behaviors have been investigated for positive streamers. However, there are few studies on negative streamers. In this paper, a two-dimensional fluid model is used to simulate the behavior of a negative streamer encountered with a cloud of positive ions. Simulation results indicate that the negative streamer behaves like a free streamer when the ion cloud has a low charge density. After initiation near the needle tip, the streamer propagates along the axis, passes through the ion cloud, and finally reaches the anode vicinity along a straight line. When the streamer reaches the ion cloud, its head radius (R0) is investigated as a function of parameters, including the voltage amplitude and the gap width, as well as the charge density, axial position, and spatial size of the ion cloud. At a given moment, electric field strength and electron density near the streamer head increase with increasing charge density of the ion cloud. In the case of a high charge-density ion cloud, after a primary streamer propagates some distance along the axis, a positive secondary streamer, and a negative secondary streamer start to propagate from the cloud to the cathode and the anode, respectively.

Outside Front Cover: Plasma Process. Polym. 6/2023

Outside Front Cover: Microwave atmospheric pressure plasma jet generated from substrate integrated waveguide resonator by Chaoxia Zhao et al (e2200230).

DISCHARGE DUTY CYCLES EFFECTS OF 20 KHZ AIR ATMOSPHERIC PRESSURE PLASMA JET ON METHYLENE BLUE SOLUTION DEGRADATION

The degradation of methylene blue (MB) using air atmospheric pressure plasma jet (air APPJ) in contact with liquid was proposed. In this study, an AC-driven air APPJ using three discharge duty cycles (30%, 50%, and 80%) of a neon transformer was investigated. In each discharge duty cycle, the ignition and extinguishment phases were characterized. The constituent particles of the air APPJ in the gas phase were observed by an optical emission spectrophotometer (OES). The OES results of all discharge duty cycles found the NO (A-X) bands, •OH radical, N2 second positive system, N2 first negative system, N+, N, and O. The emission spectra produced by the discharge duty cycle of 80% were the highest relative intensity. The effects of the different discharge duty cycles on the acidity and conductivity of water with and without MB were also determined. The complete dye degradation within 30 min was obtained in the discharge duty cycle 80%, which played an essential role in carrying reactive species from the gas phase to the liquid phase, thus promoting the degradation of MB. The best reaction kinetic rate k is 0.1692 min-1, which is six times compared to discharge duty cycle 50%.

Direct growth of long magnetic carbon nanotubes on Incoloy heating elements and its hydrophilic surface modification by atmospheric pressure plasma jets

Direct growth of long magnetic carbon nanotubes on Incoloy heating elements and its hydrophilic surface modification by atmospheric pressure plasma jets