Gas Discharge Research Articles

Simulation of a pulsed CO2 plasma based on a six-temperature energy approach

Abstract Recent time-resolved measurements of gas and vibrational temperatures in pulsed glow discharges have fostered the development and validation of detailed kinetic models to understand the underlying heating dynamics. The models published so far have been successful in identifying the fundamental processes underlying vibrational and gas heating in pure CO2 discharges; however, this has come at the cost of including vibrational kinetics with thousands of reactions. This makes these models not compatible with self-consistent computational fluid dynamics (CFD) codes, which are needed to develop new plasma reactors operating at high pressures or with complex flow patterns and capture the relevant dynamics in multi-dimension. In this work, we solve separate energy balance equations for the asymmetric and symmetric vibrational modes of CO2, as well as for the vibrational modes of CO and O2, the gas temperature, and the electron temperature, making it a six-temperature (6T) plasma model. This eliminates the need to include a vast array of vibrational levels as separate species, drastically reducing the number of reactions in the model. The model is compared with experimental measurements conducted in a pulsed CO2 glow discharge at 6.7 mbar. Excellent agreement is observed for the temporal evolution of the vibrational and gas temperatures, confirming that our approach is suitable for modeling systems under significant non-equilibrium conditions, paving the way for coupling detailed CO2/CO/O2/O kinetics with CFD codes.

A prediction model for electrical strength of gaseous medium based on molecular reactivity descriptors and machine learning method.

Ionization and adsorption in gas discharge are similar to electrophilic and nucleophilic reactions. The molecular descriptors characterizing reactions such as electrostatic potential descriptors are useful in predicting the electrical strength of environmentally friendly gases. In this study, descriptors of 73 molecules are employed for correlation analysis with electrical strength. These molecular descriptors are categorized into two types: area-related descriptors and reactivity-related descriptors. Furthermore, the predictive performance between statistical models and machine learning models is compared. The statistical models include multiple linear regression, and polynomial regression, while machine learning models consist of K-nearest neighbors, random forest, and gradient boosting decision trees. The results indicate that machine learning models are generally better than statistical models in terms of predictive accuracy and stability, with gradient boosting decision trees demonstrating the best performance. Specifically, the coefficient of determination and mean squared error on the testing set after 1000 training iterations are 0.864 and 0.105, respectively. Therefore, the application of molecular reactivity descriptors and machine learning methods can effectively predict the electrical strength of gaseous medium. The Gaussian 16 software is employed to optimize the molecular structure with the M06-2X functional and def2 series basis sets in this study. Then, the Multiwfn is utilized for wavefunction analysis to obtain molecular surface descriptors.

Plasma stratification in ac discharges in noble gases at low currents

Plasma stratification in ac discharges in noble gases at low currents

Plasma and Electric Property Analysis together with Resonance Regulation Experiment of MPT on TM<sub>011</sub> Mode

Microwave plasma thruster (MPT) is one type of electrothermal thruster, inside of which the plasma can be formed through gas heating by microwave energy and accelerated by nozzle to generate thrust. According to the different principle and operating procedure, the specific impulse of MPT is higher than that of chemical thruster and lower than that of magnetic confinement ion and Hull thruster, however the thrust of MPT is higher than that of magnetic confinement ion and Hull thruster and lower than that of chemical thruster. Therefore MPT possesses the excellent qualities of chemical and electric thruster, which will make it has the possibility of applying in space. Inside of the MPT cylindrical cavity, plasma changing procedure and microwave electric field distribution together with TM<sub>011</sub> resonant state influence the thruster performance seriously. According to the previous MPT formed through continuous regulation on the resonant sate of cylindrical cavity, it is needed to research a newly fixed and simple MPT, which will simplify the resonant state regulation and provide important basement for further study. Therefore the plasma procedure is analysis to find the best gas discharge condition, otherwise the microwave electric field intensity and power density distribution inside of the cavity running on TM<sub>011</sub> resonant sate is calculated to analyse how the parameters is influenced by the cavity dimensions. The resonant state is finely regulated to study how it is influenced by the dimension of cylindrical cavity and microwave coupling probe with ball and half ball structure. The result of theoretical analysis and calculation shows that the lowest discharge power of helium gas is present at the condition of 489Pa and microwave electric density distribution inside of the cavity is beneficial as the ratio of length to diameter greater than 1. As the length and radius of microwave coupling ball probe is suitable, the experiment of resonant state regulation shows that the shortest cylinder cavity is on the best optimum resonant sate, and its resonant frequency is very near to 2.45GHz. The helium discharge experiment demonstrates that this shortest cavity matched by the suitable ball probe have the property of high microwave power utilizing and easy discharge of helium gas, which will make MPT operation reliably.

Registration of Different Types of Water with Corona Gas Discharge Effects and Parameters of Brightness

Registration of Different Types of Water with Corona Gas Discharge Effects and Parameters of Brightness

Investigations of Microwave Switching in Gas Discharge Tube With Two-Electrode Spark Plasma Ignition

Investigations of Microwave Switching in Gas Discharge Tube With Two-Electrode Spark Plasma Ignition

TESTING FIREBALL DIAMETER AND DURATION OF 227 GRAM CARTRIDGES CONTAINING ISOBUTANE

The aim of the work was to verify equations describing the diameter and duration of the fireballin relation to small tanks containing LPG. As a result of testing small, three-piece bayonet-typecartridges containing 227 g of isobutane, it was observed that the fireball parameters may varysignificantly depending on the discharge direction of the medium. After the bottom gas discharge(BD) the fireball was found to have a significantly larger observed diameter than during thetop discharge (TD), amounting on average to 4.58 and 3.63 m, respectively. An analysis of themaximum fireball diameter (rF), the total fireball duration (tF) and the time to reach the maximumfireball value (tMR) has shown that in the case of TD there is significantly greater convergence withrelationships presented in the literature than is the case with BD. Comparing the static fireballmodels, it can be noticed that for the TD tests the rF values the closest to experiment are obtainedin the case of the Williamson&Mann, Hasegawa Sato (1977), Lithiou&Maud (butane) and CCPSequations. In the case of BD tests, convergence with models is much lower, with the smallest errorobserved for the relationship presented by TNO (12.5%). The tMR and tF values calculated for thedynamic models of Martinsen & Marx and Pritchard are much shorter than those obtained in theexperiment, and greater deviations may be noticed in the case of BD, especially in relation to thePritchard model. The research showed that the fireball growth rate for the tested cartridges is muchlower than predicted in the analysed models.

Characterization of plasma contacts to cadmium telluride photodetector in ultrathin gas discharge cell

In the present work, the physical properties at the contact of single crystal cadmium telluride semiconductor with gas discharge plasma have been investigated. It is shown that charge carriers in the plasma, together with incident infrared radiation, contribute to the enhancement of the photocurrent in the gas discharge cell. At sufficiently high voltages (more than 2.5 kV) in the gas discharge cell, positive feedback associated with the effect of the plasma on the semiconductor surface is observed. The results of theoretical calculations and experimental experience are in satisfactory agreement, from which the physical meaning of the proportionality coefficient is determined, taking into account the plasma effect on the photoconductivity of the photodetector. The use of a double plasma contact contributes to the damping of the spatial instabilities of the photocurrents in the gas discharge cell, allowing the use of low-resistance photodetectors at the input of the device. Similar results at room temperature have been obtained for the first time on the basis of single-crystal cadmium telluride.

CALCULATION PROGRAM OF THE ABSORPTION PROCESS IN NITRIC ACID PRODUCTION

The modern technological process is a product of design and modeling. Verification of theories and technical solutions can be carried out not on existing equipment but on mathematical models, by means of calculations. This increases the safety of research activities and speeds up the design process. For large research institutions and manufacturers, it is advisable to use specialized software such as MatLab, ASPEN or SimSci. Such environments have a large number of libraries and applications, which make them multifunctional. At the same time, the vast majority of users use only a small number of narrowly specialized functions that correspond to the direction of their activity. Mastering programming skills has become an integral part of modern education. Creating calculation programs based on mathematical models is not a difficult task for scientists. The rapid development of programming languages and technologies allows choosing the most appropriate ways of creating programs. According to experts, C# has been in the top 5 popular programming languages for many years. The use of this language is closely related to the .NET technology, which is intended for creating cross-platform applications. Microsoft Corporation provides the possibility of free use of its product MS Visual Studio, which also includes C#. The article describes a program created for use in researching the operation of an absorption column for the absorption of nitrogen oxides in the production of nitric acid. When developing the program, a standard calculation algorithm was used, according to which industrial devices operating in Ukraine were calculated. The algorithm also takes into account the latest information on the influence of technological parameters and physico-chemical processes. The program is created with a minimalistic interface and data entry options both from the program window and from a text file. The results of calculating the influence of oxygen addition on the concentration of nitrogen oxides in the discharge gas are given. The main purpose of the program is to study the operation of the column as an object of automation. The proposed program can be supplemented with new options, such as automatic calculation of gain coefficients for specified channels, batch processing based on data from a file, and others. Also, the program can be used for teaching students and performing research.

РАСЧЕТ ВРЕМЕНИ ИСТЕЧЕНИЯ ВОДОРОДА ИЗ БАЛЛОНА ДЛЯ ОПРЕДЕЛЕНИЯ ХАРАКТЕРИСТИК АВАРИЙНОЙ ВЕНТИЛЯЦИИ

Выполнены расчеты по определению времени истечения водорода и смеси водорода с углекислотой из баллонов емкостью 0,04 м3 при различном начальном давлении газа через отверстия различного размера. Выявлены закономерности влияния различных параметров на время истечения газов. Показано, что при некоторых условиях можно избежать давления взрыва газовой смеси свыше 5 кПа в случае разгерметизации баллона с газом. When determining the room category by explosion and fire hazard, it is assumed that all the contents of the device, cylinder or other equipment completely go into the room, mixed with air, then the mixture explodes. Such a scenario is found the most dangerous. If the room is equipped with emergency ventilation activated by a signal from a fast-acting gas analyser, it is allowed to reduce the mass of flammable gas or vapour when calculating the explosion pressure. When gas in high pressure equipment enters the room, the time of entry depends on the gas quantity, pressure and other properties of the gas. The regulatory documentation for fire safety does not provide recommendations on calculating the gas discharge time from the equipment of the final volume, accompanied by pressure decrease. The purpose of this work is to estimate the gas discharge time from industrial cylinders with a capacity of 0.04 m3 depending on various factors. The task of the work is to calculate the K coefficient in the formula for determining the required air exchange rate of emergency ventilation. To solve this problem, there is considered the discharge of several combustible gases from cylinders with a volume of 0.04 m3 through holes of different diameters at different values of initial gas pressure. It is shown that when hydrogen flows out of a cylinder with an initial pressure of 20 MPa through a hole with a diameter of 4 mm, which corresponds to the full opening of the valve, the discharge time is 26 seconds, and when discharging under the same conditions through a hole with a diameter of 1 mm, the discharge time increases up to 346 seconds. In order to determine the possibility of protecting a room with hydrogen cylinders from an explosion of a hydrogen-air mixture, there were made calculations of explosion pressures values depending on the volume of the room. There are established conditions for the use of emergency ventilation to ensure explosion safety in an accident with a gas cylinder. In order to reduce the explosion pressure for this room to 5 kPa, it is necessary to increase the discharge time up to 300 s (5 minutes). Two ways to increase the flow time are considered: reducing the size of the hole (by inserting a washer into the cylinder valve) and preliminary dilution of combustible gas with incombustible gas when filling the cylinder. It is possible to use both methods at the same time to increase the gas discharge time from the cylinder.

Study on discharge characteristics of low-temperature sub-atmospheric pressure under steep change rate voltage

Aiming at the gas discharge problem in electric aircraft, this work studies the gas discharge characteristics at low-temperature sub-atmospheric pressure. A gas discharge shooting platform was built, and the discharge process was photographed by intensified charge-coupled device (ICCD). A two-dimensional axisymmetric model of needle-plate electrode gas discharge was established, and three sets of Helmholtz equations were used to solve the photoionization. The results show that under the same voltage, the electric field intensity in the discharge process increases first, then decreases and finally increases again. The discharge speed increases with the increase of altitude, and the electron density in the streamer decreases with the increase of altitude. The development speed of the streamer in the middle stage is higher than that in the early stage, and the speed increases more obviously with the increase of altitude. The development speed of the streamer in the later stage is lower than that in the middle stage, but with the increase of altitude, the development speed of the streamer in the later stage is higher than that in the middle stage.

Discharge image reconstruction and frequency domain analysis based on event data

AbstractOptical image method has been the earliest and most used direct method for observing gas discharge. Currently, research on gas discharge monitoring based on visible light mainly relies on high‐speed cameras, but the large size, significant data storage requirements, and susceptibility to interference from complex backgrounds and lighting conditions limit their further application. Dynamic vision sensing (DVS) technology is a neuromorphic sensing technology that asynchronously measures the luminance changes at each pixel. It offers advantages such as a large dynamic range (>120 dB), high temporal resolution (up to 1 µs), and small data volume (MB level). In this study, dynamic vision sensing technology was employed to monitor both 30 mm short‐gaps and 1080 mm long‐gaps discharge processes simultaneously. This study developed the CountImage encoding method for event data and conducted image reconstruction, time‐domain analysis, and frequency‐domain characteristic analysis based on the event data. The results show that the event‐reconstructed images are highly consistent with the high‐speed camera images, and the arc development process and its path can also be clearly observed. Additionally, this study discovered a correlation between the electrical characteristics and event information during the discharge process. In the time domain, the duration of the maximum DVS event count closely matches the duration during which the voltage drops to zero during flashover. In the frequency domain, the Pearson correlation coefficient between the event stream spectrum and the voltage signal spectrum is greater than 0.95. Both the maximum number of brightening events (ONmax) and the maximum number of darkening events (OFFmax) are positively correlated with the voltage applied between the electrodes. This study demonstrates that, compared to the GB/s data rate of high‐speed cameras, this approach can record the discharge process and accurately reconstruct the discharge process, arc morphology, and discharge path at MB/s data rates, while also adapting to changes in brightness without the need for exposure adjustment. Additionally, there is a positive correlation between the frequency‐domain characteristics of the event data and the voltage characteristics. These results indicate that dynamic vision sensing holds promise as a replacement for high‐speed cameras in laboratory discharge observations and could be even effectively applied to discharge monitoring in electrical equipment in real grid.

Thermodynamic Analysis of Cyclic Operation of On-Board Nanoporous Carbon-Based Adsorbed Methane Storage Tank with Various Thermal Control Systems

Thermal effects of adsorption and desorption, leading to temperature fluctuations and losses of adsorption storage systems capacity in the processes of gas charging and discharging, are the main obstacle to the wide practical application of adsorbed natural gas (ANG) technology. This work presents a numerical simulation of heat and mass transfer processes under various cyclic operation modes of a full-scale adsorption storage tank with various thermal control systems. The high-density monolithic adsorbent KS-HAM, obtained on the basis of industrial activated carbon KS-HA, was used as the adsorption material. The phase composition, surface morphology, and porous structure of the sorbents were studied. The adsorption of methane on the KS-HA adsorbent was measured. It is shown that increasing the duration of charging leads to obtaining additional capacity of the ANG system; however, the final efficiency and benefit at the end of the charging–discharging cycle are determined by the efficiency of the thermal control system and the gas-discharging mode. It has been shown that the presence of a finned thermal control system allows for charging the adsorption storage tank 3–8 times faster and provides an 8–24% greater amount of gas discharged at the discharging stage compared to the ANG system without fins.

STUDY OF ELECTRODYNAMICS’ CHARACTERISTICS OF GAS DISCHARGE IN A NEEDLE-PLANE SYSTEM WITH ONE LIQUID ELECTRODE

Researches were conducted on the electrodynamics’ characteristics of gas discharge in a needle-plane electrode system with one liquid electrode under the application of high voltage of two types: unipolar negative pulse and combined (sum of DC and high-frequency AC high voltage) ones. This is necessary in many applications, particularly for water purification. Metal needle electrodes made of stainless steel were used, some of which were subjected to various treatments (polishing, coating with zinc nitride, titanium nitride or titanium oxide). It was shown that applying combined high voltage in the electrode system with a nitride coating results in a mean current 2 times smaller. When using a unipolar negative high-voltage pulse, the maximum mean discharge current was obtained with the untreated electrode system. This is due to the presence of a greater number of micro-protrusions on the needle electrodes, which leads to increased electric field intensity in the generation zone.

Hybrid Nanogenerator Harvesting Electric‐Field and Wind Energy for Self‐Powered Sensors on High‐Voltage Transmission Lines

AbstractTriboelectric nanogenerators (TENGs) show potential for powering distributed sensors in the smart grids. However, most studies on TENG's applications for energy harvesting from transmission lines primarily focus on vibration and wind energy, neglecting the abundant electric‐field energy from transmission systems. This study proposes a triboelectric‐electrostatic hybrid energy harvester (TEHEH) that integrates a triboelectric nanogenerator with an electric‐field energy harvester (EFEH) to simultaneously capture wind energy and electric‐field energy from the surroundings of transmission lines. The TENG and EFEH can generate open‐circuit voltages of 1280 and 2800 V, respectively, with output powers of 14.3 and 28.9 mW. Hybrid energy harvesting achieves an average power of 6.1 times that of TENG and 2.4 times that of EFEH, demonstrating its superiority. The dual‐channel energy management circuit, utilizing a gas discharge tube and the LTC‐3588, enables the hybrid nanogenerator to effectively power a wireless sensor node, demonstrating its practicality in the complex environments of power transmission lines. This work offers robust technical support for the development of self‐powered monitoring devices on high‐voltage transmission systems.

Combining Cold Atmospheric Plasma and Environmental Nanoparticle Removal Device Reduces Neurodegenerative Markers.

Ageing leads to a gradual deterioration of the organs, with the brain being particularly susceptible, often leading to neurodegeneration. This process includes well-known changes such as tau hyperphosphorylation and beta-amyloid deposition, which are commonly associated with neurodegenerative diseases but are also present in ageing. These structures are triggered by earlier cellular changes such as energy depletion and impaired protein synthesis, both of which are essential for cell function. These changes may in part be induced by environmental pollution, which has been shown to accelerate these processes. Cold Atmospheric Plasma (CAP) or atmospheric pressure gas discharge plasmas have shown promise in activating the immune system and improving cellular function in vitro, although their effects at the organ level remain poorly understood. Our aim in this work is to investigate the effect of a device that combines CAP treatment with the effective removal of environmental nanoparticles, typical products of pollution, on the activity of aged mouse brains. The results showed an increase in energy capacity, a reduction in reticulum stress and an activation of cellular autophagic clearance, minimising aggresomes in the brain. This leads to a reduction in key markers of neurodegeneration such as tau hyperphosphorylation and beta-amyloid deposition, demonstrating the efficacy of the tested product at the brain level.

Plasma-activated media selectively induces apoptotic death via an orchestrated oxidative stress pathway in high-grade serous ovarian cancer cells.

High-grade serous ovarian cancer (HGSOC) is the most common and aggressive type of ovarian cancer. Due to a lack of an early detection testand overt symptoms, many patients are diagnosed at a late stage where metastasis makes treatment very challenging. Furthermore, the current standard treatment for HGSOC patients, consisting of debulking surgery and platinum-taxane chemotherapy, reduces quality of life due to debilitating side-effects. Sadly, 80-90% of patients diagnosed with advanced stage ovarian cancer will die due to treatment resistance. As such, novel therapeutic strategies for HGSOC that are both more effective and less toxic are urgently required. Here we describe the assessment of cold atmospheric pressure (CAP) gas discharge technology as a novel treatment strategy in pre-clinical models of HGSOC. Plasma-activated media (PAM) was generated using cell growth media. HGSOC cell lines, patient ascites cells and primary tissue explants were tested for their response to PAM via analysis of cell viability, cell death and oxidative stress assays. Our data show that PAM treatment can be more effective than standard carboplatin chemotherapy at selectively targeting ovarian cancer cells in primary patient samples. Further, we also observed PAM to induce apoptosis in HGSOC cancer cell lines via induction of oxidative stress and mitochondrial-mediated apoptosis. These findings suggest that PAM is a viable therapeutic strategy to test in in vivo models of ovarian cancer, with a view to develop an intraperitoneal PAM-based therapy for HGSOC patients. Our studies validate the ability of PAM to selectively target tumour tissue and ascites cells. This work supports the development of PAM towards in vivo validation and translation into clinical practice.

Temporal evolution of opto-galvanic effect in normal glow discharge of argon

Argon (Ar) atomic gaseous normal glow discharge is generated using two electrodes in low pressure in vacuum condition. The rate of change is constant a steady state in normal glow discharge. The shock wave is generated using the resonant absorption or induced emission in plasma state. The change of impedance is measured in terms of current or voltage of normal glow discharge. The aim of the work is to measure temporal profile voltage signal with the ionization probability and life time of two state lower and upper excited state in the plasma, theoretically calculated and experimentally. Results have been studied using Nd-YAG laser pumped tunable dye laser at pulsed width 7 ns and repetition rate 10 Hz. The opto-galvanic effect (OGE) is observed in normal glow discharge using the induced absorption and emission in one and two photon transitions. The change of impedance of normal glow discharge have been studied in temporal profile experimentally and calculated theoretically.

The Main Geohazards in the Russian Sector of the Arctic Ocean

The Arctic region, including vast shelf zones, has enormous resource and transport potential and is currently key to Russia’s strategic development. This region is promising and attractive for the intensification of global economic activity. When developing this region, it is very important to avoid emergency situations that could result in numerous negative environmental and socio-economic consequences. Therefore, when designing and constructing critical infrastructure facilities in the Arctic, it is necessary to conduct high-quality studies of potential geohazards. This paper reviews and summarizes the scattered information on the main geohazards in the Russian sector of the Arctic Ocean, such as earthquakes, underwater landslides, tsunamis, and focused fluid discharges (gas seeps), and discusses patterns of their spatial distribution and possible relationships with the geodynamic setting of the Arctic region. The study revealed that the main patterns of the mutual distribution of the main geohazards of the Russian sector of the Arctic seas are determined by both the modern geodynamic situation in the region and the history of the geodynamic evolution of the Arctic, namely the formation of the spreading axis and deep-sea basins of the Arctic Ocean. The high probability of the influence of seismotectonic activity on the state of subsea permafrost and massive methane release is emphasized. This review contributes toward better understanding and progress in the zoning of seismic and other geological hazards in the vast Arctic seas of Russia.

Partial discharge noise comparison and recognition method based on multi-channel smooth decoherence algorithm applied to GIS

Abstract In order to further improve the accuracy of the online monitoring spectra of partial discharge in gas insulated switchgear, a partial discharge distributed monitoring system is studied, and distributed sensors are used to simultaneously obtain ultra-high frequency electromagnetic wave signals. Based on the accumulated partial discharge spectra of each sensor, the smooth decoherence noise recognition algorithm is proposed on a long-term cumulative spectral pattern, which is used to analyse the correlation between the spectra of each sensor. Furthermore, a method for determining whether partial discharge is an internal signal is proposed, and its effectiveness is verified by practice, the results confirmed that the algorithm can avoid the misjudgement of partial discharge results caused by distributed sensor interference.