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Conventional magnetron sputter deposition of B 4 C uses Ar as the working gas. Here, we explore the magnetron sputter deposition of B 4 C with a Ne plasma, which is expected to exhibit larger sputtering yields than Ar. We study properties of films deposited with different substrate tilt angles with the magnetron source operated in either direct-current (DC) or radio-frequency (RF) mode in an Ar or Ne plasma. Results show that the B 4 C film properties are determined by a combination of sputtering ballistics and effects of the working gas on the plasma discharge and gas phase scattering of depositing species flux. At constant discharge power, deposition rates for Ar and Ne plasmas are similar, which is attributed to balancing effects of a higher ballistic sputtering yield of Ne and lower ion flux to the target. Both depositing B and C neutral species and bombarding ions have higher energies for the case of Ne plasmas. Films deposited with the RF-driven Ne plasma exhibit a uniform non-columnar structure, lowest oxygen impurity content, and highest mass density and mechanical properties at a cost of Ne incorporation and larger compressive residual stress. [ABSTRACT FROM AUTHOR]

Rationale: The Δ36S standard deviation measured in a conventional isotope ratio mass spectrometer such as MAT 253 is ca 0.1‰ to 0.3‰. At this precision, it is difficult to resolve the origin of non‐mass‐dependent sulfur isotope fractionation in tropospheric sulfate aerosol and in Martian meteorites or small deviations from the canonical mass‐dependent fractionation laws. Interfering ions with m/z at 131 of 36SF5+ are suggested by the community as the cause of the poor precision, but the exact ion species has not been identified or confirmed. Methods: Here we examined the potential interfering ions by using a Thermo Scientific ultrahigh‐resolution isotope ratio mass spectrometer to measure SF6 working gas and SF6 gases converted from IAEA‐S1/2/3 Ag2S reference materials. Results: We found that there are two resolvable peaks to the right of the 36SF5+ peak when a new filament was installed, which are 186WF42+ followed by 12C3F5+. However, only the 12C3F5+ interference peak was observed after more than three days of filament use. 12C3F5+ is generated inside the instrument during the ionization process. Avoiding the interfering signals, we were able to achieve a Δ36S standard deviation of 0.046‰ (n = 8) for SF6 zero‐enrichment and 0.069‰ (n = 8) for overall measurement start from silver sulfide IAEA‐S1. Conclusions: Aging the filament with SF6 gas can avoid the interference of 186WF42+. Minimizing the presence of carbon‐bearing compounds and avoiding the interfering signals of 12C3F5+ from 36SF5+, we can improve Δ36S measurement accuracy and precision, which helps to open new territories for research using quadruple sulfur isotope composition. [ABSTRACT FROM AUTHOR]

Rationale: In stable isotope mass spectrometry, isotope delta values are normalized to internationally recognized reference scales using a combination of certified and in‐house isotope reference materials. Numerous techniques exist for performing this normalization, but these methodologies need to be experimentally assessed to compare their effect on reproducibility of isotope results. Methods: We tested normalization methods by the number of reference materials used, their matrix, their isotope range, and whether normalization required extrapolating beyond the isotope range. We analyzed eight commercially available isotope reference materials on a ThermoFinnigan Delta‐V isotope ratio mass spectrometer (IRMS) and an Elementar VisION IRMS for nitrogen and carbon isotope composition via solid combustion with an elemental analyzer and computed every possible isotope normalization (n = 612). Additionally, we assessed how sample matrix affected linearity effects on both instruments using five in‐house reference materials. Results: Normalizations exhibited the best performance when the reference materials spanning an isotope range of at least 20‰ were matrix matched with the samples and did not require extrapolation beyond the calibration curve. When these conditions were not met, the number of reference materials used had a significant effect on accuracy, with normalizations composed of two reference materials exhibiting particularly inconsistent performance at isotope ranges below 20‰. Linearity effects were found to exceed instrument precision by two orders of magnitude irrespective of matrix type and were not predicted by working gas diagnostics. Conclusions: Interlaboratory comparability of isotope results is improved when operators of elemental analyzer isotope ratio mass spectrometry (EAIRMS) systems select reference materials spanning an isotope range of at least 20‰. Additionally, using three or more isotopic reference materials, avoiding extrapolation beyond the range of the normalization curve, and matching the matrix of the reference materials to the samples improve normalizations. [ABSTRACT FROM AUTHOR]

Underground salt caverns allow large hydrogen storage capacities at low specific costs. Such storage is required to balance fluctuating hydrogen supply and constant demand of large consumers as a methanol plant from the Carbon2Chem® project. The geological and technical feasibility for developing up to 168 Mio. m3 (n.c.) or 595 GWh of working gas capacity until 2040 at a location in the Lower Rhine Bay is described. Various options for realization as well as a novel process for cavern leaching parallel to hydrogen storage operation are evaluated. Further work is required including geological exploration and optimization of brine production. The main hurdles for investment decisions are the political uncertainties on the hydrogen storage market design and on the ramp‐up of the hydrogen market. [ABSTRACT FROM AUTHOR]

To reduce the working coefficient and jitter of the three-electrode gas switch used in linear transformer drivers, a novel trigger method that uses a nanosecond pulse in cooperation with the microplasma jet generated by capillary discharge was developed. A microplasma jet was generated by the nanosecond trigger pulse and injected into the follow-up breakdown gap of the gas switch to decrease the working coefficient. The influence of capillary parameters on the development of the microplasma jet was simulated. The results showed that the microplasma jet significantly reduced the breakdown delay time, jitter, and working coefficient. Increasing the capillary length and decreasing the diameter results in better triggered breakdown performance. Furthermore, the gas switch triggered by a positive pulse exhibits a lower breakdown delay and jitter. Combined with the intensified charge coupled device's shooting results, it can be concluded that the microplasma jet has a distinct influence on streamer formation, which is important for improving the working performance of the gas switch. [ABSTRACT FROM AUTHOR]

This work presents the synthesis of tungsten nanoparticles (W NPs) using a cluster source based on magnetron sputtering combined with gas aggregation (MSGA), operated with up to 81% H2 in the hydrogen/argon mixture used as a working gas. The results show that, with up to 41% H2 in discharge, the synthesis rate increases by more than 60 times, rapidly decreasing for over 50% H2 in discharge. The W dust is still produced for H2-dominated discharges (81%), and its deposition rate is small but not negligible (0.02 mg/h). The obtained W NPs are isolated, with the diameter decreasing from 50 nm to 15 nm when the amount of H2 in discharge is smaller than 41%. Over this value, the particles tend to agglomerate, forming structures similar to film-like deposits. Also, the diameter of the dust spots deposited on substrates depends on the H2 content of the discharge. This allows the efficient coating of substrates up to 26 mm wide by translating them in front of the MSGA cluster source exit aperture. Additionally, for 41% H2 in discharge, the influence of synthetic air leaks (0%–8.2%) in discharge was investigated. The deposition rate decreases rapidly (ceasing for around 6% air in discharge), and the obtained nanoparticles tend to agglomerate on the substrate (at 3.3% air content, the dust deposit has the aspect of a near-continuous film). Chemical composition investigations show a pronounced tendency for oxidation, nitridation, and oxynitride formation in the presence of air leaks. [ABSTRACT FROM AUTHOR]

The surface states of gas sensing materials based on oxide semiconductors are closely related to their sensing dynamics. In this work, using surface engineering, p-type ZnCo2O4 architectures are prepared through a feasible hydrothermal strategy followed by subsequent annealing treatment and are applied for the detection of inert xylene gas. The as-prepared ZnCo2O4 architecture (ZCO-300) exhibits a higher response and selectivity toward xylene gas at a working temperature of 170 °C. Moreover, the ZCO-300 sensor also presents superior stability/reliability, good moisture resistance and a low detection limit of 0.1 ppm. The larger number of oxygen vacancy defects and higher specific surface area in ZCO-300 not only promote the catalytic oxidation of xylene gas by p-type semiconductor ZnCo2O4, but also provide more gas adsorption sites and surface reaction sites on sensing material surfaces, thereby endowing ZCO-300 with superior xylene gas sensing properties. [ABSTRACT FROM AUTHOR]

Microwave plasma is known for its versatility in providing tailored operating conditions (pressure, working gas composition and residence time of reagents) for specific applications. Microwave plasma sources (MPSs) are vital in modern applications, demanding continuous improvement. This work introduces a coaxial-line-based nozzleless MPS that operates at atmospheric pressure at an unique frequency of 915 MHz. The measured electrodynamic characteristics in nitrogen of the MPS highlighted the need for improved energy efficiency of the device. The main novelty of this work lies in improving an energy efficiency of the presented MPS, which led to an advanced new version of the device. To achieve this, a dual strategy is employed. Firstly, numerical simulations are used to design a construction modifications to the MPS, which should increase the efficiency of transferring microwave energy from the microwave source to the generated plasma. In this step, a standard model for homogeneous plasma and a two-port equivalent method were used. Then, the theoretical results were experimentally validated by manufacturing a new energy improved version of the MPS. In the new MPS the achieved reflected microwave power (losses) was less than 3% of incident microwave power in the tested range of nitrogen flow rate (50–100 Nl/min). Compared to the MPS before improvement, this means a two-fold decreasing the reflected microwave power. To test the new MPS, the electrodynamic characteristics of the new device version and properties of the microwave plasma generated in nitrogen, using optical emission spectroscopy (OES), were investigated. The OES was used to determine the vibrational Tvib and rotational Trot temperatures of nitrogen molecules and molecular ions. In this work, the estimated Tvib and Trot temperatures for nitrogen molecules ranged from 4000 to 5300 K, depending on discharge conditions, while for nitrogen molecular ions, the temperatures changed between 4700 and 6100 K, respectively. Both the Tvib and Trot temperatures decrease linearly along the plasma flame. [ABSTRACT FROM AUTHOR]

A pressure gauge was incorporated into a two‐chamber glass H‐tube to continuously monitor the pressure inside a reactor when working with gases. The ex situ generated H2, D2, acetylene and CO2 were tested in pressure gauge reactors, and calibration curves were plotted. A series of unsaturated compounds with two or more double C=C bonds accessible for hydrogenation were synthesized for hydrogenation. The hydrogenation proceeded well due to constant pressure control, and the desired products were isolated in good yields. The same hydrogenation procedures were then carried out using steel autoclaves to verify the results and compare them. Surprisingly, almost the same results were obtained, confirming the effectiveness of self‐made glass reactors. The hydrogenation mechanism was further investigated using D‐labeled reagents. The kinetics of hydrogenation was studied both in manometric glass reactors and in steel autoclaves, which showed a similar nature of the main process in both reaction units. Thus, the created reactors can be effectively used in barometric transformations instead of steel autoclaves in appropriate cases. [ABSTRACT FROM AUTHOR]

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High power impulse magnetron sputtering (HiPIMS) discharges with a zirconium target are studied experimentally and by applying the ionization region model (IRM). The measured ionized flux fraction lies in the range between 25% and 59% and increases with increased peak discharge current density ranging from 0.5 to 2 A/cm 2 at a working gas pressure of 1 Pa. At the same time, the sputter rate-normalized deposition rate determined by the IRM decreases in accordance with the HiPIMS compromise. For a given discharge current and voltage waveform, using the measured ionized flux fraction to lock the model, the IRM provides the temporal variation of the various species and the average electron energy within the ionization region, as well as internal discharge parameters such as the ionization probability and the back-attraction probability of the sputtered species. The ionization probability is found to be in the range 73%–91%, and the back-attraction probability is in the range 67%–77%. Significant working gas rarefaction is observed in these discharges. The degree of working gas rarefaction is in the range 45%–85%, higher for low pressure and higher peak discharge current density. We find electron impact ionization to be the main contributor to working gas rarefaction, with over 80% contribution, while kick-out by zirconium atoms and argon atoms from the target has a smaller contribution. The dominating contribution of electron impact ionization to working gas rarefaction is very similar to other low sputter yield materials. [ABSTRACT FROM AUTHOR]

Today, aramid fibers are well known as a high‐performance and ideal material for reinforcement purposes in rubber product manufacturing including hoses, tires, cables, and conveyors composites. However, surface modification of aramid fiber is necessary to solve poor interfacial adhesion between aramid fibers and the rubber matrix. Accordingly, in the present study, the effect of the surface modification of aramid fibers using atmospheric pressure plasma treatment with different precursors on adhesion to the rubber matrix was investigated. For that, the plasma coating was conducted using argon as the main working gas, and toluene, acetonitrile, tetraethyl orthosilicate (TEOS), and hexamethyldisiloxane (HMDSO) as liquid precursors. The physical–chemical characterization of the layer confirmed the successful deposition of amorphous carbon, amorphous nitride‐carbon, SiO2, and Polydimethylsiloxane (PDMS)‐like coating layers on the surface of aramid fibers by using toluene, acetonitrile, TEOS, and HMDSO as precursors, respectively. Overall, the result showed that the plasma surface modifications with acetonitrile precursor leads to the increase in interfacial adhesion of aramid/rubber composite, while retaining the tensile strength, and flame resistance properties of aramid as original fibers. Notably, the results of this study confirm the potential use of atmospheric pressure plasma for surface modification of aramid yarn to produce functional aramid for use in rubber composites. Highlights: The plasma‐coated aramid using HMDSO, TEOS, toluene, and acetonitrile precursors was prepared; and its effect on the tensile properties of aramid fiber as well as interfacial adhesion between aramid/rubber composite was investigated.The positive effect of atmospheric pressure plasma coating using HMDSO precursor on the tensile properties of aramid fiber was revealed.The positive effect of atmospheric pressure plasma coating using toluene and acetonitrile on the interfacial adhesion between aramid/rubber composite was revealed.The positive effect of atmospheric pressure plasma coating using TEOS precursor on the flam resistance property of aramid fiber was revealed.This study provides valuable insights into the effect of the different plasma‐coated organosilicon and hydrocarbon precursors on the interfacial adhesion between aramid/rubber composite. [ABSTRACT FROM AUTHOR]

Plasma behavior in cesium‐seeded argon (Ar/Cs) and xenon‐seeded argon (Ar/Xe) disk‐shaped MHD generators are compared under almost the same working conditions using r‐θ two‐dimensional simulation. For both working gases, uniform plasma occurs at the optimum load resistance, and the power outputs are the same under an identical inlet ionization degree. For Ar/Cs, plasma is stable and uniform in the range of electron temperature of 4300–5800 K basically according to the linear perturbation theory. In the actual plasma in the MHD generator, however, the uniform plasma still can be maintained even at higher electron temperatures due to the low three‐body recombination coefficient of Ar. For Ar/Xe, on the other hand, uniform plasma is maintained when the characteristic time of the electron number density is longer than the residence time of the working gas where the electron temperature is around 4300–8600 K, even though unstable plasma is suggested from the linear perturbation theory. [ABSTRACT FROM AUTHOR]

In this work, a novel analytical time-sensitive model for Ericsson engines was developed taking into account the heat transfer phenomena between the working gas and the cylinder walls in the compressor and the expander. For the calculation of the mass flow entering/exiting each cylinder, another dedicated flow model was developed to account for the pressure drop at the valves. From the energy equilibrium taking into consideration the time-dependent thermal response of the cylinder walls and the enthalpy entering/exiting each cylinder through the valves, an analytical solution of the working gas pressure and temperature can be obtained for every time step and consequently, the thermal efficiency of the engine can be calculated. A case study was performed where the thermal efficiency of an Ericsson engine was calculated for different rotational speeds and heat exchanger gas temperatures. It was observed that with higher temperatures thermal efficiency maintained a more stable behaviour with a weak dependence on rotational speed. The thermal efficiency of the engine in the performed case studies was found in the range of 10% to 14%. The valve timing of the Ericsson engine was optimized in order to achieve the highest thermal efficiency possible. The thermal efficiency of the engine could be increased up to 26% as a percentage after a thorough optimization of the valve timing. Finally, backflow phenomena accounting for thermal efficiency drop were studied. The developed model can also be applied to other types of external combustion engines such as Stirling engines. [ABSTRACT FROM AUTHOR]

The equipment and method for measuring the plasma flow velocity of a quasi-stationary high-current plasma accelerator (QSPA) based on high-speed Doppler shift spectroscopy are described. Time sampling of measurements can reach 100 kHz, which makes it possible to study in detail processes lasting about 1 ms or more. The correspondence between the flow velocity values obtained by Doppler shift spectroscopy and the time-of-flight method has been demonstrated. The results of measurements are presented, showing that the velocities of the QSPA plasma flow lie in the range of 30–160 km/s, depending on the energy input into the discharge and the composition of the working gas. [ABSTRACT FROM AUTHOR]

Multilayer structures based on the In‐Zn‐O (IZO) system with modulated oxygen doping have been developed as a TCF (transparent conductive film) alternative to ITO or IGZO layers in the LC and OLED displays. The minimum resistivity (3.37 Ohm*cm) and the maximum concentration of free charge carriers correspond to the layers synthesized in an atmosphere of pure argon, while the maximum mobility (39.18 cm2/V*s) corresponds to the layers synthesized in the atmosphere of both argon and oxygen 99.6%/0.4% mixture. Thin‐film periodic structures with gradient modulation of oxygen content in thickness have been fabricated by periodically changing the oxygen concentration in the composition of the working gas during spraying at a substrate temperature of 100 °C. The structures consist of alternating layers with a high concentration of free charge carriers and layers with high mobility. As a result of the single layers' thicknesses optimization the thin‐film periodic structures with a minimum resistivity of 2.89 Ohm*cm have been made. The resistivity is lower than in homogeneous layers of the same composition. The alternation of layers of optimal thickness provides high carrier mobility, it is inherent to layers synthesized in the atmosphere of 99.6/0.4 argon and oxygen mixture at high concentration. The mobility value is close to the value achieved in the layers synthesized in the pure argon atmosphere. This material provides fabrication of high quality, stable and low cost transparent electrodes or TFT layers with performances corresponding to parameters of traditional materials. [ABSTRACT FROM AUTHOR]

Storing hydrogen gas in natural gas storage sites could help provide the large-scale energy storage required to decarbonize global energy supply. Here, we determine that active natural gas storage sites in the United States (U.S.) can store 312 TWh of hydrogen working gas, which is most of the hydrogen storage energy required for a 100% renewable energy grid in the country. We also provide the first assessment of the geologic reservoir quality for hydrogen and static storage capacity of inactive natural gas storage sites in the U.S. Our analysis evaluates each site for conversion to hydrogen storage based on their reservoir properties, and we find that these sites can store 3.9 TWh of hydrogen working gas. We conclude that these inactive sites provide a favorable route to commence seasonal hydrogen storage, but larger storage volumes, such as those provided by active sites, will be required in the future. • Storing hydrogen gas in natural gas storage sites can provide seasonal energy storage. • Active natural gas storage sites could store 312 TWh of hydrogen working gas. • Inactive natural gas storage sites could store 3.9 TWh of hydrogen working gas. • Active sites could store most of the hydrogen gas needed in a future electrical grid. • Inactive sites with good reservoir quality are strong candidate hydrogen storage sites. [ABSTRACT FROM AUTHOR]

The Stirling engine heater is a key component between the external heat source system and the working circulation system, which drives the piston by transmitting heat energy to the working gas. In this study, based on the U-shaped tube heater, a disc heater was designed and manufactured, and the average photo-thermal conversion efficiency reached 56.58% under outdoor conditions. The heat flux distribution of the two heaters at the same solar normal direct irradiance of 1000 W/m2 was compared using TracePro optical simulation software. The results show that the average heat flux density of the disc heater (2.083 · 103 W/m2) is more uniform than that of the U-shaped tube heater, and the effective radiation area is larger, which verifies the rationality of the design of the disc heater. [ABSTRACT FROM AUTHOR]

The diffusion absorption refrigeration (DAR) systems are driven by heat and utilize a binary solution along with an inert gas as the working fluid. In commercial applications, the choice of binary solutions operating with an auxiliary gas is typically limited to ammonia‐water or water‐lithium bromide combinations. The focus of this study is to explore the viability of using tetrafluoropropene (R‐1234yf, an HFO refrigerant) as the refrigerant, dimethylacetamide (DMAC) as the absorbent, and helium as the auxiliary gas. As the thermodynamic properties of this specific binary solution are yet to be studied, experimental investigations are conducted to obtain these properties. The results allow the establishment of the pressure‐temperature and concentration relationships and determine the mixture's enthalpy for various temperatures. Subsequently, both numerical and experimental analyses of the diffusion absorption system are performed. The experimental findings show that, under certain concentrations of the components and with appropriate heat input, temperatures in the evaporator reached below 0 °C. However, the system exhibits low coefficient of performance values, high generation temperatures, and overall inefficiency, suggesting that this particular binary solution may not be well‐suited for diffusion absorption cooling systems. [ABSTRACT FROM AUTHOR]

In nonequilibrium slip and jump conditions, normal gas velocity and temperature gradients are used to calculate the gas slip velocity and temperature at the surface, respectively. Gökçen et al. (Computational fluid dynamics near the continuum limit, AIAA Paper No. 87-1115, 1987, and Gökçen and MacCormack, Nonequilibrium effects for hypersonic transitional flows using continuum approach, AIAA Paper No. 89-0461, 1989) stated that the tangential velocity and temperature of the gas molecules before a collision with the surface could be interpreted as the macroscopic tangential velocity and temperature of the gas molecules at the so-called near-wall distances auλ and aTλT away from the surface, respectively. The coefficients au and aT are the order of unity. In the present work, new forms of the slip and jump conditions are proposed by modifying the Gökçen slip and jump conditions to include the coefficients (au, aT). Numerical investigations are comprehensively conducted to determine the numerically proper values (au, aT) for the hypersonic rarefied gas flows. Cases such as the circular cylinder in cross-flow and sharp and blunted leading edge wedge are considered in the present work, with nitrogen as the working gas. The simulation results show the significant effects of the coefficients (au, aT) on the accuracy of the slip velocity and surface gas temperature predictions, and the values of au = 1.2 and aT = 1.1 show good agreement with the direct simulation Monte Carlo data. [ABSTRACT FROM AUTHOR]

This paper investigates the dependence of operating parameters of a gas sensor based on zinc oxide obtained by the method of direct current magnetron sputtering. The production of gas sensor films was carried out using a VUP-5M vacuum unit with an original material-saving magnetron. The study of the dependence of the working parameters of the gas sensor was carried out under standard conditions. It was found that with increasing humidity, the electrical resistance of the gas sensor decreases and, accordingly, the sensitivity to the target gas decreases. A significant reaction of the gas sensor to an increase in humidity was observed in the range of 65–80 % relative humidity. The mechanism of influence of relative humidity on the sensitivity of a gas sensor based on ZnO was investigated. The change in resistance of the gas sensor is caused by trapped electrons on adsorbed oxygen molecules on the surface of the sensitive layer. The capture of electrons from the conduction zone leads to bending of the conduction zone and an increase in the space charge zone, respectively, to a change in the resistance of the sensitive layer of the gas sensor. In the atmosphere, when O2 molecules are adsorbed on the ZnO surface, they remove an electron from the conduction band. The reaction of oxygen adsorbed on the ZnO surface with reducing gases and the replacement of adsorbed oxygen with other molecules changes the bending of the conduction band and reduces the area of space charge. Adsorption of water on the surface of zinc oxide occurs according to the dissociation mechanism, which consists in the adsorption of steam molecules or hydroxyl groups with the subsequent displacement of previously adsorbed oxygen and free electrons and, accordingly, leads to a decrease in the sensitivity of the gas sensor. In addition, the adsorption of water vapor (H2O) molecules leads to less chemisorption of oxygen species on the ZnO surface due to the reduction of the surface area, which is responsible for the sensor response. Approaches to reduce the influence of relative humidity on the sensitivity of a gas sensor based on zinc oxide have been proposed. [ABSTRACT FROM AUTHOR]

A series of probe measurements of low-temperature plasma parameters ahead of the front of the incident shock wave was carried out using a double-diaphragm shock tube DDST-M of the Institute of Mechanics of Moscow State University. Such investigations are needed for determining the electron concentration in front of the shock wave. This characteristic is important for the safety of the spacecraft flight since it's directly affects to communication problems during the descent and is necessary for adequate description of kinetic processes behind the shock wave. Nitrogen, oxygen, air, and argon were used as working gases. The results obtained make it possible to describe the processes of the photoelectric effect and photoionization of gas particles due to the hard radiation of a shock-heated medium, to evaluate the effect of these processes on the change in the probe potential, and to measure the electron concentration. The probe measurements were synchronized with the registration of the light flux, which was carried out using an avalanche photodiode and a 9-frame video camera located at the end of the shock tube. Data from the camera and piezoelectric sensors record the dynamics of the opening of the diaphragm, as well as the process of formation of a shock wave in the gas under study. • Electron emission due to the photoelectric effect. • Photoionization of the gas ahead of the shock front. • Estimation of electron concentration from the probe measurement. [ABSTRACT FROM AUTHOR]

The modern concept of metrological assurance of the analytical gas-measuring instruments is presented based on the use of reference gas mixture composition materials in pressurized tanks. These reference materials are most commonly used during analytical gas measurements as the means for transferring units of mole fraction and mass concentration of the components in gaseous and gas-condensate media. In the reference materials, the content of the target component(s) in the gaseous medium (analytical matrix) is certified. To ensure the uniformity of analytical gas measurements, all produced reference gas mixture composition materials are traced to the State primary standard of units of mole fraction, mass fraction, and mass concentration of the components in gaseous and gas-condensate media (GET 154-2019). A procedure for ensuring metrological traceability of the reference gas mixture composition materials with the use of GET 154-2019 is presented, which accounts for the constantly increasing pool of analytical gas-measuring instruments and for the emergence of new measuring tasks in various industry sectors and areas of environmental control. Currently, a pool of secondary and work standards has been created at the enterprises that produce reference gas mixture composition materials, and the traceability of such materials to GET 154-2019 has been implemented according to the state verification schedule. It was shown that the variety and multitude of the actual measurement tasks involving gas analysis in various industrial sectors and social sphere determine the need for prioritizing directions for improving the existing base of reference materials, including the composition of the GET 154-2019 standard and the range of the reference gas mixtures. The strategic program, developed for the period up to 2030 by the Working Group on Gas Analysis of the Consultative Committee for Amount of Substance of the International Bureau of Weights and Measures, has been analyzed, and a review of the long-term tasks of analytical gas measurements was performed. The currently utilized latest-generation GET 154-2019 standard ensures reproduction, storage, and transfer of the units of mole fraction and mass concentration of the components in gaseous and gas-condensate media ranging from 1.5 · 10−8 to 99.99999% and from 1.0 · 10−6 to 2.0 · 105 mg/m3, respectively. The GET 154-2019 characteristics have been confirmed by the results of participation in about 90 comparisons. The results of these international comparisons are provided, which confirm the comparability of the obtained and reference values of the target component content in gaseous mixtures. The calibration and measurement capability database of the International Bureau of Weights and Measures has published about 400 positions related to analytical gas measurements. [ABSTRACT FROM AUTHOR]

Spokes are regions of enhanced ionization in magnetron sputtering discharges that are interesting because of their role for magnetron operation and their potential effect on deposition processes. Here, we show that spokes can intentionally be generated by introducing a strong-to-weak magnetic field strength transition along the racetrack. Spokes are triggered at the transition point from an accelerating electron drift when weakening the magnetic field strength. The spokes are then propagating against the electron drift into the strong magnetic field strength section of the racetrack. At the weak-to-strong magnetic field transition, we observe the inverse effect. The electron drift is decelerated at this point, creating a region of enhanced optical emission. From rectangular racetracks this is known as the cross-corner effect. Here, we show that a corner is not necessary for observing that effect. Pronounced spokes at low working gas pressure of 0.2 Pa exhibit a substructure that could be caused by the diocotron instability previously predicted by computer simulations. [ABSTRACT FROM AUTHOR]

A time-dependent global model is developed for deep oscillation magnetron sputtering (DOMS) with a Cr target to characterize the plasma using the working Ar gas at a pressure of 0.8 Pa. An input of the global model is the target voltage and current waveforms at charging voltages from 260 to 400 V. The plasma densities vary synchronously with the oscillations of target power. During the on-time of a micropulse, the gas atoms are ionized first to ignite the plasma and subsequently the metal ions follow to sustain the discharge. During the off-time, the gas ions dominate the afterglow. The DOMS possesses a characteristic of alternating gas/metal discharge in the time domain. The peak values of plasma densities increase linearly with charging voltages, which is mainly attributed to the higher Cr+ ion density. The discharge transits from gas dominated to metal dominated at high charging voltage. The working gas rarefaction in DOMS discharge is enhanced at higher charging voltages. At charging voltages higher than 360 V, the metal self-sputtering comes into the runaway regime temporarily as indicated by the self-sputtering parameters exceeding unity, generating the dense and metal-rich plasma. The metal self-sputtering is promoted by gas rarefaction. The electrons tend to ionize the metal atoms after the gas atoms are depleted. The decreased grain size and elevated nano-hardness of the Cr thin films are explained by structure transition from zone I to zone T due to the efficient metal ion bombardment to the growing thin films as the charging voltage increases. [ABSTRACT FROM AUTHOR]

The discharge mode characteristics of cathodes may strongly influence the discharge stability and performance of electrostatic thrusters. In this article, discharge characteristics and mode transition phenomenon of the ring-cusp magnetically confined plasma bridge neutralizer (RCM-PBN) were experimentally studied using argon as the working gas. The dependences of anode current and oscillation amplitude on anode voltage, argon flow rate, heater power, and cathode-to-anode distance were investigated. Plasma properties were measured and plasma plume images were taken under different discharge modes. Two distinct discharge modes were observed during the experiments: high oscillation mode and low oscillation mode. In the high oscillation mode, the plasma plume appears dim, the anode current is low, and the oscillation level is more than 2%. While in the low oscillation mode, a spot-like structure close to the orifice is observed. The plume becomes brighter, the anode current increases, and the oscillation level decreases below 2%. The RCM-PBN was found to transition into the low oscillation mode by increasing anode voltage, flow rate, heater power and by decreasing the cathode-to-anode distance. [ABSTRACT FROM AUTHOR]

O2 impurity in the working gas of an He/CF4 atmospheric pressure plasma jet (APPJ) can affect the discharge dynamics and the density of reactive species. Therefore, a two-dimensional (2D) fluid model is built in order to explore the influence of an O2 admixture on the propagation and F-containing species distribution of He/CF4 APPJ. The addition of 0.1% O2 accelerates the ionization rates of APPJ due to the increase of Penning ionization reactions of O2, resulting in the increases of axial speed and F-containing reactive species (CF4+, CF3+, CF2+, CF+, F+, CF3, F, CF3−) when APPJ approaches the dielectric surface. The addition of O2 has the inhibitory effect on the rise of some F-containing reactive species (CF3+ and F). As O2 concentration increases to 2%, the concentration of F-containing reactive species shows a downward trend due to the increase of excitation energy loss and an electron attachment reaction of O2. Different from the axial speed, the radial speed decreases continuously with the increase of O2 because of the high O2 concentration on the dielectric surface when APPJ propagates radially. This also results in a reduced distribution of reactive species fluxes. The excitation energy loss and electronegativity of O2 and CF4 in the case of He + 0.5% CF4 + 0.5% O2 have been presented in this paper. It is discovered that excitation energy loss of O2 is stronger than that of CF4, but the electronegativity of CF4 is stronger than that of O2. [ABSTRACT FROM AUTHOR]

Underground hydrogen storage in porous media (UHSP), typically employing depleted natural gas reservoirs, is being increasingly contemplated as a potentially viable energy storage option to compensate for intermittent renewable energy sources. A layer of cushion gas (typically N 2 , CH 4 or CO 2) is proposed to be accommodated in such UHSP systems to allow for pressure and volume control during hydrogen (the so-called working gas) injection and withdrawal, while also serving as a barrier to prevent excess water contamination. One significant challenge in such UHSP systems is the potential mixing between this working gas (hydrogen) and the cushion gas within the relevant reservoir. Such mixing increases the risk of unacceptable extracted hydrogen contamination (with the cushion gas), often requiring expensive surface hydrogen purification processes. Therefore, the use of a cushion gas has potential economic implications. Accurate determination of the extent of this mixing requires reservoir simulations, which depend on dispersion coefficient (K L) data as input. Such data are however not available in the literature for hydrogen under relevant reservoir conditions. Here we present novel measurements of K L for the dispersion of hydrogen in the three prospective cushion gases as a function of system pressure (50–100 bar) and for displacement velocities ranging from 0.2 to 8.4 cm/min. • The dispersion coefficient (K L) between hydrogen and potential cushion gases was measured using a core flooding apparatus. • Measurements were executing using a Fontainebleau sandstone and N 2 , CH 4 and CO 2 as the potential cushion gases. • K L was obtained as a function of displacement velocity (0.2–8.4 cm/min) and system pressure (50–100 bar). • K L data for gaseous N 2 , CH 4 and CO 2 was scaled by the relevant diffusion coefficient, this was not the case for liquid CO 2. [ABSTRACT FROM AUTHOR]

The object of this study is the ST-25 Hall thruster with limited discharge power, no more than 200 W, designed by Flight Control LLC (Ukraine). The problem that was solved in the current paper was to determine the effect of residual gas pressure in vacuum chambers on the operating parameters of the Hall thruster. To solve this task, the operating parameters of the ST-25 thruster were determined, which was tested in three vacuum chambers with different sizes of residual pressure. As a result of the laboratory study into the operating parameters of the ST-25 thruster, the volt-ampere characteristics of the engine discharge at fixed values of the working gas (xenon) flow rate were obtained. The dependences of the engine thrust on the mass flow rate of the working gas at fixed values of the discharge voltage were derived. Based on the experimental data, the dependences of the specific impulse of the engine anode unit on the discharge voltage, as well as the dependence of efficiency of the engine anode unit on the discharge voltage were calculated. The studies showed that when the residual pressure in the vacuum chamber is reduced by 2–3 times, the operating parameters of the engine increase by 15–20 %. Such a reduction in residual pressure increases thrust by 25–40 %. Special feature of the results is the determination of threshold values of residual gas pressure in vacuum chambers during experimental studies, in which the operating parameters of the Hall thruster are similar to its operating parameters under space conditions. This work’s findings could be used in practice when conducting experimental studies of electric rocket engines, when it is necessary to estimate the operating parameters of Hall thrusters that will be obtained under actual space conditions. [ABSTRACT FROM AUTHOR]

Underground hydrogen storage in geological structures is considered appropriate for storing large amounts of hydrogen. Using the geological Konary structure in the deep saline aquifers, an analysis of the influence of depth on hydrogen storage was carried out. Hydrogen injection and withdrawal modeling was performed using TOUGH2 software, assuming different structure depths. Changes in the relevant parameters for the operation of an underground hydrogen storage facility, including the amount of H2 injected in the initial filling period, cushion gas, working gas, and average amount of extracted water, are presented. The results showed that increasing the depth to approximately 1500 m positively affects hydrogen storage (flow rate of injected hydrogen, total capacity, and working gas). Below this depth, the trend was reversed. The cushion gas-to-working gas ratio did not significantly change with increasing depth. Its magnitude depends on the length of the initial hydrogen filling period. An increase in the depth of hydrogen storage is associated with a greater amount of extracted water. Increasing the duration of the initial hydrogen filling period will reduce the water production but increase the cushion gas volume. [ABSTRACT FROM AUTHOR]

In this article, the effects of hydrogenation amount (0–80%), oxygen content (14–18%), and strain rate (10–1000 s−1) on the emission characteristics of NO and CO in moderate or intense low‐oxygen dilution (MILD) fractional combustion are studied under the actual working conditions of gas turbine (T = 723 K, P = 16.5 atm). The pathway of NO and CO production and the reaction with the greatest influence on their emissions are analyzed. In the findings, it is indicated that NO emissions are suppressed at lower hydrogen levels, while the addition of hydrogen leads to a decrease in CO emissions. Specifically, the key reaction for NO formation is H + NO + M = HNO + M, whereas CO emissions are primarily controlled by the direct reaction OH + CO = H + CO2. Furthermore, the reduction of oxygen levels effectively suppresses NO and CO emissions during MILD combustion. The variation in oxygen level exerts the greatest influence on the reaction rate of the NNH pathway. High concentrations of O2 are identified as the primary cause of elevated CO levels in MILD combustion. Finally, elevating the strain rate in MILD combustion demonstrates a mitigating effect on NO and CO emissions. [ABSTRACT FROM AUTHOR]

We have developed a container system for in-situ measurement of CO2 and CH4 that significantly reduces the consumption of working standard gases to a level less than one order of magnitude smaller than that required by a common method. It uses on-site compressed air to track the baseline drift of sensors. JR-STATION (Japan-Russia Siberian Tall Tower Inland Observation Network) consisted of this system installed at nine sites in Siberia. The system acquires semi-continuous data by recording several minutes of averaged data after gas replacement time. We have updated the calculation method for deriving CO2 and CH4 concentrations to determine their uncertainty for each data simultaneously. Furthermore, we estimated the system's reproducibility based on the repeated measurement of on-site compressed air. The CO2 and CH4 concentration reproducibility mostly varied by less than 0.2 ppm and five ppb, respectively. Uncertainties of time-averaged data were sometimes higher than the measurement uncertainty for each period, suggesting that the data include atmospheric variability during the measurement period of several minutes. Data users should consider the difference between the two uncertainties to select optimal data, depending on their focusing spatial scale. The CO2 and CH4 data measured with the NDIR and the tin dioxide sensor exhibited good agreement with those measured by the CRDS, respectively. [ABSTRACT FROM AUTHOR]

The exploration and development potential of shale gas reservoirs in the Sichuan Basin is enormous; however, it also faces difficulties such as complex structures, strong heterogeneity, and unclear geophysical response characteristics. Fine prediction of geostress is an important part of shale gas exploration and development, which directly affects the implementation effect of reservoir evaluation, well trajectory design, and fracture reconstruction. The existing geostress prediction techniques lack high-precision seismic data constraints, making it difficult to accurately reflect the planar distribution characteristics of geostress in the block with rapid changes in complex tectonic zones. At the same time, the geophysical response characteristics of geostress in the Sichuan Basin are unknown, and the geostress seismic prediction technology lacks theoretical basis. This paper combines numerical simulation and physical experiments and defines the characteristics of the geophysical response of shale gas reservoirs in the Sichuan Basin changing with the stress field, and technical countermeasures for geostress seismic prediction have been established to provide technical means for accurate prediction of the geostress field in the shale gas block. Based on the geostress sensitive parameters obtained from prestack seismic inversion, the geostress field prediction of a shale gas work area in the Sichuan Basin is realized. [ABSTRACT FROM AUTHOR]

The gas fuels are from many aspects more convenient for use than liquid fuels. First of all, the gas fuels are already in gaseous aggregate state, so it is not necessary the vaporization, the mixing is easier, and by that the formation of homogenous mixture is much easier, than in the case of liquid fuels. Also, the gas fuels are considered to be more perspective fuels, due their chemical composition. In most cases, the gas fuels have less carbon in their chemical composition, which is good from the aspect of the ecology. Less carbon leads to the lower emission of harmful components such are carbon-monoxide (CO) and unburnt-hydrocarbons (HC). In this paper, experimentally was investigated the IC engine working cycle with the Compressed Natural Gas (CNG), for the cases of stratified mixture. It was found out that the degree of the stratification, greatly influences on the combustion process, and in this way on the IC engine efficiency. [ABSTRACT FROM AUTHOR]

Numerical modeling of the coupled processes of deformation of the coal massif with s mine working and gas filtration in the disturbed area was carried out. The modeling takes into account changes in rock permeability depending on their stress state. Cases of a frame supported or roof bolted working are considered. Inelastic strain zones, distributions of stress fields, strains, permeability coefficients, and gas pressure are determined. Curves of changes in geomechanical and filtration parameters over time are presented. The results are analyzed. It is shown that roof bolting can be used not only to maintain the stable state of mine workings but also as a technological means of reducing methane emissions into the mine atmosphere. [ABSTRACT FROM AUTHOR]

Geoscientists working in the oil and gas industry have a crucial role in combating climate change. In particular, by carrying out regional and local characterization and field projects to demonstrate that different types of geologic storage reservoirs distributed over different basins can permanently and safely store CO2. Therefore, this work is aimed at determining the storage capacity, injectivity, and containment of the reservoir intended for CO2 sequestration. Well logs and 3D seismic data were used to analyze a depleted oil field, (the “HAN” field), in the Niger Delta, Nigeria. Petrophysical analysis was done on the well logs to estimate the net thickness, porosity, water saturation, and injectivity of the reservoirs. Structural interpretation was done on the seismic data, and the volumetric method was used to estimate the storage capacity of the delineated reservoirs. The fault’s sealing capacity was determined, and the resulting containment of the reservoirs was estimated. Two sand reservoirs, RES 1 and RES 2, of average thicknesses of 79 m and 93 m, respectively, were delineated across the three analysed wells. The reservoirs effective porosity was 18% and 19%, respectively, and water saturation was 18% and 35%, respectively. The storage capacity of RES 1 was estimated to be 28 MT, and RES 2 was 22 MT. The assessed storage capacity for both reservoirs gave “HAN” field a total storage capacity of approximately 50 MT. The injectivity for RES 1 and RES 2 was determined to be 337 mD and 323 mD, respectively. Based on the threshold set by the International Energy Agency, parameters obtained were observed to be greater than 10 m, 10%, 10%, 200 mD, and 4 MT for thickness, effective porosity, water saturation, injectivity, and storage capacity, respectively. The Han field is suggested as a good field for CO2 sequestration. Furthermore, the Shale Gouge Ratio (SGR) was estimated to be 29% (poor sealing zone) and 44% (moderately sealing zone) in Fault F9 for regions with RES 1 and 2, respectively, to validate their containment. It is evident from the SGR that F9 can serve as a barrier to the migration of CO2 away from the reservoir at deeper depths. [ABSTRACT FROM AUTHOR]

The results of experimental studies of a discharge system based on a pulsed (200–400 μs, 5–25 Hz) high-current (5–30 A) planar magnetron discharge with a target diameter of 125 mm and additional electron injection from a vacuum arc discharge are presented. The electron injection into the magnetron discharge is carried out from the back of the sputtered target through the central aperture, which provides additional acceleration of the injected electrons in a cathode layer of the magnetron discharge and an increase in the energy efficiency of the discharge system. The mass-to-charge ion composition of the generated plasma has been studied in a range of operating pressure up to an extremely low level of 0.2 mTorr. The conditions to achieve a high fraction of target material ions in the magnetron plasma are defined, including those in the range of low operating pressure range, where the typical magnetron discharge is characterized by an increase of a working gas ion fraction, and transfers into a low-current form. [ABSTRACT FROM AUTHOR]

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In the current study, a square assembly of four quad-atmospheric pressure plasma jets (q-APPJ) is used to treat large-sized chilli seeds simultaneously. Germination and growth characteristics improve significantly after a 10-sec treatment of q-APPJ employing argon as the working gas. Plasma-treated chilli seed is more etched and porous than those untreated seed surface, as shown in scanning electron microscopy. The chemical changes of the plasma-treated seeds showed that the Ar plasma-treatment oxidise the seed surface to enhance their wettability, stimulate the water uptake, increase the water electrical conductivity and result in improved seed germination. In addition, optical emission spectroscopy is used to detect the different plasma species present and evaluate their plasma parameters (electron temperature and density). These positive results suggested that Ar plasma-treatment, in APPJ setup, improve seed germination, and potentially improve crop yield, and food security issues. [ABSTRACT FROM AUTHOR]

The plasma density and electron temperature are governed and influenced by the high-power pulsed magnetron sputtering parameters (e.g., operating voltage, pulse width, and working gas pressure), which are critical factors in determining the quality of high-power pulsed magnetron sputtering deposited films. This article proposes a vertical cylindrical magnetron sputtering plasma model based on the equivalent magnetic charge model to study the particle spatiotemporal and electron temperature distribution in high-power pulse magnetron sputtering. The results show that the electron converges in the highest magnetic field region in high-power pulsed magnetron sputtering during the increase of argon pressure from 3 to 7 Pa. The electron density distribution width ratio decreases from 80 to 64%, reducing target utilization. At the same time, for every 1 Pa increase in pressure, the average electron temperature in the discharge region is reduced by about 2 eV, which is inversely proportional to the pressure. As the voltage increases to 1000 V, the electric field intensity increases to 2 × 105 V/m, and the distribution of sputtered particles tends to be closer to the electrode, and the cathode dark zone changes from 2 to 1 mm. The increase in voltage has little effect on the shape of the plasma particle density distribution, but the electron temperature near the electrode increases to 19 eV at high voltages. The study reveals the change of plasma particles during the magnetron sputtering process, which is of guidance for magnetron sputtering. [ABSTRACT FROM AUTHOR]

The paper reveals the problem of measuring reactive oxygen (ROS) and nitrogen (RNS) species' concentrations in plasma treated water Milli-Q. We investigate the features of the FOX method for hydrogen peroxide concentration measurement and the Griess method for nitrite ions concentration spectrophotometric measurement using two different ways of an aqueous solution treatment. In the first case, the electrode (non-conducting high-temperature ceramics) was above the aqueous solution and the discharge was in the gas phase. In the second case, the electrodes were fixed around the perimeter inside the cylindrical chamber filled with water, and working gas (air, argon) was injected into interelectrode space. Varying the duration of exposure (2–10 min) leads to changes in the chemical composition and biological activity of the liquid medium, and this approach is effective for proving of the methods in complex liquids. We found the erosion of the electrodes (stainless steel, duralumin) with the injection of argon and air. The erosion can affect reactions of the methods used, as a result, it makes a contribution to measured concentration. For further applications, it is necessary to consider these features to obtain the correct and reproducible results. When plasma exposure occurs with an electrode that is above the surface of the liquid and does not erode, both methods work in the proper way. But when erosion is present ions of eroded materials (iron, aluminum) contribute to the measurement of hydrogen peroxide concentration using the FOX method. A method with xylenol orange is proposed for taking this feature into account by measuring the concentration of metal ions. In the Griess assay it is possible to obtain strongly erroneous results due to visually similar color and close values of absorbance at the chosen wavelength (525 nm) for both low concentration of nitrites (within linear part of the calibration curve) of nitrites and high concentration (far beyond linear part of the calibration curve). In our research concentration of nitrites does drastically change in the experiment after changing material of the electrodes from stainless steel to duralumin. The Griess assay leads to the formation of a stable fluorescent complex when erosion of the metal electrodes is present. [ABSTRACT FROM AUTHOR]

A two-dimensional axisymmetric fluid model was applied to investigate the influence of N2 flow velocity on the discharge characteristics of a He plasma jet with a coaxial dual-channel inlet. Helium working gas flowed in the annular space of a coaxial tube and N2 flowed in a central stainless steel tube powered by a DC voltage. When N2 flow velocity increases from 0 m/s, the jet appears to be stratified, forming the outer side and inner side of the jet, and the electron density on the outside of the jet is much higher than that on the inside. For different N2 flow velocities, the peak densities of He+ and N2(c3π) appear in the jet head, while the peak densities of He* and N2+ both appear at the dielectric nozzle and the jet head. When N2 flow velocity is low, the Penning ionization rate is lower than the electron impact ionization rate, but when N2 flow velocity is high, it is just the opposite, which can increase the concentration of reactive species and contribute to the practical application of the jet. N2 flow velocity not only changes the length and structure of the jet but also controls the uniformity of the distribution of reactive species in the jet, which indicates that there is an optimal N2 flow velocity to make the jet longer and more uniform in space, which will greatly promote the practicality and flexibility of the plasma jet and also provide meaningful insights for optimizing and controlling the characteristics of the plasma jet. [ABSTRACT FROM AUTHOR]

The magnetic field of a magnetron serves to increase the residence time of electrons in the ionization region and thereby enables the discharge to be sustained at low working gas pressures. This hinders the electrons to reach the anode which is necessary to close the electrical circuit. At high atom densities in the ionization region, and in the presence of an electric field, collisions of electrons with heavy species consecutively push electrons across the magnetic field lines, which is known as the classical cross-field transport mechanism. At low atom densities in the ionization region, collisions are rare and the classical cross-field transport mechanism is insufficient to carry the discharge current. This gives rise to plasma instabilities, called spokes, that locally provide pathways for electrons to escape from the near-target region and across the magnetic field lines. Here, we show experimentally, for the case of a high power impulse magnetron sputtering discharge with an aluminum target, how spokes gradually disappear with the increase in local gas density. We present an analytical model that shows that under these high gas density conditions, the classical electron transport mechanism is indeed strong enough to solely carry the discharge current. This highlights the importance of the local gas density in the ionization region for the intensity of spokes in a magnetron sputtering discharge and suggests ways for process optimization. [ABSTRACT FROM AUTHOR]

This article reports on the characterization of a laboratory model 100 A-class hollow cathode with a sintered lanthanum hexaboride ( LaB 6) emitter for high-power Hall thrusters. The cathode has been fired up to 70 A with xenon as working gas. The cathode architecture, test setup, ignition procedure, and power consumption are described first. The second part of this contribution comments on the current–voltage characteristics and the discharge modes obtained for discharge currents in the 30–70 A range and flow rates in the 15–30 SCCM range. The cathode operates in a spot mode at high discharge currents and in a plume mode with large oscillations at low currents and low gas flow rate. Spectral analysis shows that most frequencies reside in the 10–200 kHz range with flat and sharp distributions in plume and spot modes, respectively. Finally, we present electron temperatures and densities measured in the cathode plasma plume by means of incoherent Thomson scattering. The two quantities decrease along the axis. The density is large (up to ∼ 10 19 m − 3 ) and increases with both the ion current and the gas flow rate. The electron temperature increases with the current and decreases with the gas flow rate. The temperature remains relatively low (<1.5 eV) in spite of large currents and applied powers. [ABSTRACT FROM AUTHOR]

Inductively coupled plasmas driven by pulsed RF power have been used by the semiconductor industry for decades as they offer numerous advantages compared to continuous mode discharges. Current state-of-the-art global models characterize the plasma under conditions where power delivery is user defined and typically constant. This work details the development of an integrated global plasma-circuit model, which couples a transient plasma model with a broader circuit model that captures the behavior of the power delivery system. The transient response of electron density n e and the magnitude of the delivered and reflected power is captured for the duration of a pulse event. The plasma model incorporates negative feedback mechanisms that enhance the magnitude of reflected power in the early ON-cycle. These feedback mechanisms include a skin depth-dependent derivation of plasma impedance and a generalized electron energy distribution function. These mechanisms decrease the rate of power delivery and d n e d t in the early power on cycle. Data taken in the global plasma-circuit model was benchmarked to hairpin probe measurements that were taken on the NC state's inductively coupled argon oxygen system. Experimental data were taken using a working gas of high purity argon at pressures ranging from 2.67 to 6.67 Pa, and center point electron densities were measured in the range of 10 9 – 10 10 cm − 3 . [ABSTRACT FROM AUTHOR]

Discharge characteristic comparisons between He and Ar plasma jets have been extensively reported, but is rarely reported for the comprehensive study of discharge mode transition from He jet to Ar jet, especially its induced liquid chemistry and biological effect. In this paper, we investigate the plasma jet mode transformation by varying the Ar contents in the He/Ar mixing working gas, particularly focusing on the effect of liquid chemistry of plasma activated water (PAW) and the corresponding inactivation effect against tumor cells in vitro. The mode transition process from He jet to Ar jet is characterized by the discharge images, the spatial temporal evolution, and the electrical and spectra measurements. It is found that the plasma jet mode displays a transition from diffuse to filamentous mode, which significantly affects the gaseous reactive species production and the ability to deliver into liquid, resulting in a huge difference in physicochemical properties and the concentration of reactive oxygen and nitrogen species in PAW. Furthermore, the A549 lung cancer cell is utilized to reveal the inactivation effect against tumor cells induced by PAW during discharge mode transition, and it is found that the PAW induced by Ar plasma jet can lead to the higher apoptosis efficiency of cancer cells due to the high production of key species (NO2−, H2O2, and ONOO−/ONOOH) under filamentous mode. This study would provide deep insights into the nature of liquid physicochemistry and its anticancer effect during plasma jet mode transformation. [ABSTRACT FROM AUTHOR]