Discharge Power Research Articles

Optimal Conversion of Food Packaging Waste to Liquid Fuel via Nonthermal Plasma Treatment: A Model-Centric Approach

The efficiency of employing a multifactorial approach to enhance the nonthermal plasma (NTP) chemical conversion of solid waste food packaging materials into liquid petroleum hydrocarbons was assessed for the first time in this study. The researchers adopted a hybrid approach which integrated the zero-dimensional (0-D) and response surface model (RSM) techniques. After their application, the researchers noted that these strategies significantly enhanced the model prediction owing to their accurate electrochemical description. Here, the researchers solved a set of equations to identify the optimisation dynamics. They also established experimental circumstances to determine the quantitative correlation among all process variables contributing to food plastic packaging waste degradation and the production of liquid fuels. The findings of the study indicate a good agreement between the numerical and experimental values. It was also noted that the electrical variables of NTP significantly influenced the conversion yield (Yconv%) of solid plastic packaging waste to liquid hydrocarbons. Similarly, after analysing the data, it was seen that factors like the power discharge rate (x1 ), discharge interval (x2), power frequency (x3), and power intensity (x4) could significantly affect the product yield. After optimizing the variables, the researchers observed a maximal Yconv% of approximately 86%. The findings revealed that the proposed framework could effectively scale up the plasma synergistic pyrolysis technology for obtaining the highest Yconv% of solid packaging plastic wastes to produce an aromatics-enriched oil. The researchers subsequently employed the precision of the constructed framework to upgrade the laboratory-scale procedures to industrial-scale processes, which showed more than 95% efficiency. The extracted oil showed a calorific value of 43,570.5 J/g, indicating that the liquid hydrocarbons exhibited properties similar to commercial diesel.

Refractory high entropy TiTaZrHfW-N/Si3N4 nano-layered alloy thin film’s oxidation resistance

Refractory high entropy TiTaZrHfW-N/Si3-N4 nano-layered alloy thin films are investigated to study the effect of nano-layered architecture and silicon (Si) mean content on their structural, mechanical, thermal properties and oxidation behavior. The films are deposited using direct current (DC) magnetron sputtering of separate Si and TiTaZrHfW targets. The Si mean content is controlled by tailoring the power discharge applied to the Si target. The deposition process led to a nano-layered architecture where Si3N4 (amorphous) and TiTaZrHfW-N (nano-crystalized NaCl FCC type structure) are alternated. By increasing the thickness of Si3N4 nano-layers, the Si mean content increases. All coatings are found to have good thermal stability after annealing under vacuum at 900 °C. Increasing Si mean content reduces the film’s hardness; however, the annealing treatment at 900 °C improves it. A super-hardness of 41 GPa is found for the post-annealed Si-free film. Si3N4 nano-layers enhance the oxidation resistance at elevated temperatures of 600, 700, and 800 °C. This oxidation resistance is further enhanced by increasing the nano-layer’s period and also by increasing the density of the films.

Influence of discharge power and grid structure on an RF-biased ion thruster

The RF-biased ion thruster applies radio-frequency (RF) power on the grid system, which can extract both ions and electrons to achieve self-neutralization. The performance of the RF-biased ion thruster is significantly influenced by the structure of the grid system and the discharge power since these factors play a crucial role in determining the focusing condition of the grid system. In this paper, the influence of discharge power and grid structure on the RF-biased ion thruster’s voltage parameters is investigated. According to the screen grid voltage waveform results under different discharge power and grid structure, the relationship between self-bias voltage and RF voltage is acquired. In order to explain the different waveform variations, the impacts of the direct impingement current as well as the oscillation of the upstream sheath voltage are considered in the theoretical calculation for self-bias voltage. It has been found that the opposite oscillation of the upstream sheath voltage is the primary reason for the decline in self-bias voltage. Moreover, the mechanisms through which discharge power and grid structure influence the self-bias voltage are explained in terms of their impact on upstream sheath oscillation. Several methods for increasing the self-bias voltage in RF-biased ion thrusters are also proposed.

Effects of pulse rise time and pulse width on discharge mode transition of SDBD plasma under repetitive pulses

Abstract Affected by environmental states and power supply parameters, the discharge mode of surface dielectric barrier discharge plasma may gradually transfer from O3 mode to NOx mode, resulting in various gas-phase species for different applications. Despite the intensive study of attempts to control this discharge mode transition by changing discharge conditions and power excitations in recent years, the effects of the pulse rise time and the pulse width on the discharge mode transition have not been discussed. In the present study, a surface dielectric barrier discharge was excited by repetitive pulses with different pulse rise times or pulse widths, and the time-varying concentrations of key long-lived species (O3 and NO2) were quantified. The results demonstrated that it was possible to modulate the discharge mode by adjusting pulse rise time/pulse width. The quenching of O3 was observed to occur at a faster rate and the mode transition was noted to occur at an earlier point in time as the pulse rise time decreased from 225 ns to 125 ns and the pulse width increased from 0.5 μs to 4 μs. The employment of a zero-dimensional model for the analysis of plasma chemical kinetics revealed that the reduction in pulse rise time and the prolongation of pulse width resulted in an increase in the mean vibrational energy of N2(v) and a more rapid electrode temperature rise caused by plasma heating. The former enhanced the generation of NO, while the latter accelerated the thermal decomposition of O3, thereby promoting the speed of mode transition.

Degradation of Atrazine in Water by Dielectric Barrier Discharge Combined with Periodate Oxidation: Enhanced Performance, Degradation Pathways, and Toxicity Assessment.

The widespread occurrence of atrazine (ATZ) in water environments presents a considerable risk to human health and ecosystems. Herein, the performance of dielectric barrier discharge integrated with periodate (DBD/PI) for ATZ decomposition was evaluated. Results demonstrated that the DBD/PI system improved ATZ decomposition efficiency by 18.2-22.5% compared to the sole DBD system. After 10 min treatment, the decomposition efficiency attained 82.4% at a discharge power of 68 W, a PI dosage of 0.02 mM, and an initial ATZ concentration of 10 mg/L. As the PI dosage increased, the decomposition efficiency exhibited a trend of initially increasing, followed by a decrease. Acidic conditions were more favorable for ATZ removal compared to alkaline and neutral conditions. Electron paramagnetic resonance (EPR) was adopted for characterizing the active species produced in the DBD/PI system, and quenching experiments revealed their influence on ATZ decomposition following a sequence of 1O2 > O2-• > IO3• > OH•. The decomposition pathways were proposed based on the theoretical calculations and intermediate identification. Additionally, the toxic effects of ATZ and its intermediates were assessed. This study demonstrates that the DBD/PI treatment represents an effective strategy for the decomposition of ATZ in aquatic environments.

Dynamic of mode transition in air surface micro-discharge plasma: reactive species in confined space

Abstract Flexible surface micro-discharge plasma is a non-thermal plasma technique used for treating wounds in a painless way, with significant efficacy for chronic or hard-to-heal wounds. In this study, a confined space was designed to simulate wound conditions, gelatin was used to simulate wound tissue. The distinctions between open and confined spaces were explored, and the effects of temperature, humidity, discharge power, and the gap size within the confined space on the plasma characteristics were analyzed. It was found that, temperature, humidity and discharge power are important factors that affect the concentration distribution of active components and the mode transition between ozone and nitrogen oxides. Compared to open space, the concentration of ozone in confined space was relatively lower, which facilitated the formation of nitrogen oxides. In open space, the discharge was dominated by ozone initially. As temperature, humidity and discharge power increased, nitrogen oxides in the gas-phase products were gradually detected. In confined space, nitrogen oxides can be detected at an early stage and at much higher concentrations than ozone concentration. Furthermore, as the gap of the confined space decreased, the concentration of ozone was observed to decrease while that of nitrate increased, and the rate of this concentration change was further accelerated at higher temperature and higher power. It was shown that ozone concentration decreased from 0.11 µmol to 0.03 µmol and the nitrate concentration increased from 20.5 µmol to 24.5 µmol when the spacing in the confined space was reduced from 5 mm to 1 mm, the temperature of the external discharge was controlled at 40 °C, and the discharge power was 12 W. In summary, this work reveals the formation and transformation mechanisms of active substances in air surface micro-discharge plasma within confined space, providing foundational data for its medical applications.

Advancements in biomedical coatings: A comprehensive review of DC magnetron sputtering on Ti–6Al–4V alloy

This study investigates the application of DC magnetron sputtering (MS) technology for producing TiN and ion-substituted Ca-P coatings on dental implant materials, demonstrating ultimate tensile strength (UTS) of 887 MPa, a modulus of elasticity of 11.3 × 106 MPa. The influence of various physical vapor deposition (PVD-MS) parameters—such as substrate temperature, post-heat treatment, deposition duration, discharge power, and bias voltage—on the characteristics of these coatings is examined. The research evaluates the advantages and limitations of PVD-MS in fabricating TiN and Ca-P coatings, with an emphasis on their impact on surface topography and chemical composition, which are critical factors influencing cellular behavior. The study reveals that while ion-substituted HA coatings can enhance cell adhesion, they may also exhibit cytotoxic effects, potentially limiting cell growth. It compares osteogenic cell proliferation rates between low-crystalline HA coatings and highly crystalline variants on Ti-based substrates, highlighting significant performance disparities. Additionally, PVD-MS demonstrates robust adhesion capabilities and facilitates the incorporation of therapeutic ions, effectively replicating bioapatite properties. The addition of coating on the substrate promotes additional strengthening mechanisms of the layers, leading to improved wear resistance compared to an alloyed substrate. Estimated values for hardness range between 7.2 and 8.4 GPa, and for Young's modulus, they range from 126 to 162 GPa. The study highlights the potential of PVD-MS in creating nanostructured Ca-P coatings on biodegradable metals, alloys, and polymeric biomaterials. This technology improves corrosion resistance, biocompatibility, chemical stability, wear resistance, and overall performance in various biomedical applications.

Simulation study of a novel approach to couple compressed CO2 energy storage with compression heat storage in aquifers

The integration of energy storage systems is essential for addressing the limitations of renewable energy generation, such as intermittency and fluctuations. This study introduces a porous media adiabatic compressed CO2 energy storage system (PM-ACCES) that combines thermal energy storage with compressed CO2 energy storage within aquifers at different depths. PM-ACCES aims to reduce the overall system complexity by eliminating the need for thermal storage systems at the ground level to store compression heat, while simultaneously integrating CO2 energy storage with sequestration. Through comprehensive numerical simulations and thermodynamic modelling, the study evaluates the performance of the PM-ACCES system under various operating conditions. The results show that, under the default conditions of this study, the average discharge power and charge power of the PM-ACCES with solar heating over 30 days are 4663.7 kW and 2342.9 kW, respectively, with a corresponding discharge capacity of 18,655 kWh and a charge capacity of 23,429 kWh. The PM-ACCES system can operate without external heat sources, achieving a discharge power of 3045.31 kW and a discharge capacity of 12,156 kWh, while attaining a higher round-trip efficiency of 51.93 %. Additionally, the study examined various factors affecting the energy storage performance of the solar-heated PM-ACCES. The findings suggest that improving wellbore thermal insulation and utilizing deeper aquifers can significantly enhance energy storage performance. However, increasing the circulation flow rate, while boosting charge and discharge power, reduces the round-trip efficiency. These findings provide a robust foundation for future optimization of CO2-based energy storage systems, offering a promising solution for integrating renewable energy into the power grid.

Synergistic plasma and platinum catalysts interactions in CO2 reforming of propane at room temperature: The role of supports

This study investigates the synergistic impact of plasma and catalyst in a hybrid non-thermal plasma system integrated with 1 wt% Pt catalysts supported on diverse catalyst supports (γ-Al2O3, SBA-15, HZSM-5, CeO2, TiO2, and multi-wall carbon nanotube (CNT)) at ambient conditions in dry reforming of propane (DRP). To optimize the reaction, the impact of in-situ plasma reduction time was investigated over the Pt/Al2O3 catalyst at varying durations before the DRP reaction. The most favorable catalytic performance was observed at a reduction time of 60 min due to having the highest surface area (284 m2/g), which might result in smaller Pt particle size, and the effective reduction of oxidation states to Pt0. A comparison of reduction sources also revealed that the plasma-reduced catalyst outperformed the other, which was attributed to the agglomeration of Pt active sites during the thermal reduction process. The chemo-physical properties of different catalysts directly affected the plasma characteristics and catalytic performance. Pt/Al2O3 exhibited the highest performance, attributed to having the smallest mean Pt particle size (0.94 nm) and highest discharge power (13.97 W), effective capacitance (1.41 nF), and charge transfer (0.34 μC) during DRP reaction, leading to a 13 % and 15 % increase in CO2 and C3H8 conversions, respectively, compared to plasma-only mode. The catalytic performance showed that the synergy of catalysts with higher basic sites and plasma characteristics, along with smaller Pt particle size, resulted in high reactant conversion and syngas selectivity. Binary HRTEM images also indicated the presence of more soft carbon (coke) in the pore channels of the spent Pt/HZSM-5 catalyst than in spent Pt/Al2O3.

Direct simulation Monte Carlo-driven optimization of vacuum intakes for air-breathing electric thrusters in very low earth orbits

The performance of an atmosphere-breathing electric propulsion (ABEP) intake has been investigated with a focus on the direct simulation Monte Carlo (DSMC) method. A numerical dataset was derived from extensive DSMC analysis of rarefied flow across various intake configurations. The intake geometry, based on a concept from the literature, comprises a cylindrical body with four annular coaxial channels and a conical convergent diffuser. By maintaining the aspect ratio of the coaxial channels, the DSMC simulations were performed by changing three key parameters: inlet area, convergent diffuser angle, and operating discharge voltage, at altitudes ranging from 140 to 200 km. The analysis of the ABEP system revealed that altitude has the most significant influence on the discharge power, while the effects of the diffuser angle and inlet area are comparatively smaller. Analysis at fixed altitudes reveals a strong influence of altitude on discharge power, while the diffuser angle and the inlet area play a minor role. The results also show that the sensitivity of the discharge power to the diffuser angle increases as the altitude approaches the highest level of 200 km. Furthermore, an evolutionary-based optimization methodology was applied, taking into account the requirements of a drag-to-thrust ratio of less than 1 and a discharge power of less than 12 kW. Optimization analysis in the full altitude range revealed that the optimal diffuser angle falls within the narrow range of 15°–20°, corresponding to an optimal operating altitude range of 170–178 km.

Methodology for measuring the energy characteristics of two-electrode gas discharge plasma switches in the picosecond range using the reflectometry method

This research proposes a new technique for measuring the energy characteristics (losses of energy in the spark gap, related to light radiation, ionization, excitation, and heating of the working gas during the development of plasma; discharge power) of two-electrode gas dischargers in the subnanosecond range. The work examines the voltage waveforms across the discharge gas gap and the discharge current waveform obtained by the reflectometry method in the subnanosecond range. To do this, the traditional technique for measuring such characteristics was modified. This allows us to restore the back edge of the voltage pulse across the discharge gap at the breakdown delay and the breakdown stages, which is usually lost in the subnanosecond range when measuring such waveforms. For modification, calculated data on the ionization frequency were used. This allows us to replace the plasma of the discharge gap with a constant resistor in those sections of the voltage waveform where the characteristic ionization time is more than an order of magnitude longer than the duration of the voltage pulse applied to the gap. The waveforms of the voltage across the discharge gap and the discharge current obtained in this way allowed us to calculate the power dynamics and total energy introduced into the gas discharge plasma. These parameters are important both for calculating the efficiency of gas switches and for other applications of gas discharge plasma, in particular laser pumping.

A plasma-catalytic system with MgO/NiO/Ni cathode for SF6 degradation

In this work, a plasma-catalytic system in DC discharge with MgO/NiO/Ni (MNN) cathode is proposed for the degradation of SF6 greenhouse gas. The discharge power with MNN cathode is significantly increased compared with Ni cathode due to its good electron emission characteristics, and an effective and stable SF6 degradation performance is achieved in this multi-needle plate discharge system. Besides, surface discharge occurs on the MNN cathode in addition to the needle tips, which is believed to be conducive to the catalytic decomposition of SF6 on the MgO surface. Nontoxic products of MgF2 and MgSO4 are detected on the MgO layer after discharge from various characterizations (XRD, XPS, FTIR and Raman, etc.), suggesting that there is a series of catalytic reactions between SF6/intermediates and MgO. The addition of appropriate O2 (O2:SF6 = 1:1) in the background is not only conducive to the defluorination decomposition of SF6 in ionization region, but also O atom generated from O2 discharge promotes the formation of MgF2 and MgSO4, thus resulting in an effective SF6 degradation performance. Then, the possible degradation mechanism of SF6 in gas phase and on the MgO layer is discussed and the possible degradation pathways are proposed. This research first demonstrates the effectiveness of enabling degrading SF6 gases in a plasma-catalytic system with MNN cathode.

Real-time predictive control assessment of low-water head hydropower station considering power generation and flood discharge

In the real-time operation of cascade reservoirs, when the discharge flow of the upstream power station changes frequently, the downstream power station with a low head and small storage capacity has to adjust the gate or turbine frequently to keep the water level safe. This paper proposes a real-time optimal scheduling model based on model predictive control theory(MPC), considering the interaction between power generation and flood discharge. Firstly, the correlation analysis is carried out between the outflow of the Zhentouba hydropower station(ZTB) and the inflow of the Shaping II Hydropower Station(SP), and the spatio-temporal hydraulic connection between the ZTB and SP is obtained. The fuzzy relationship between tail water level and discharge flow is accurately described using numerical simulation, considering the interaction between power generation and discharge. Secondly, based on the precise description of inflow and outflow, a high-precision water level rolling prediction model is constructed using the water balance principle. Finally, based on the MPC, the real-time control model of SP is constructed. The results show that the water level process is steadier, with fewer gate adjustments. Compared with the observed number of gate adjustments in 2020, the number of reservoir gate adjustments after model optimization is reduced by 73.26%. It improves the operation efficiency and safety of the hydropower station and provides a guidance basis for the optimal operation of the SP.

Highly asymmetrically configured single atoms anchored on flame-roasting deposited carbon black as cathode catalysts for ultrahigh power density Zn-air batteries

Iron group element-based single atom (SA) catalysts are highly regarded as promising alternatives to commercial Pt/C for catalysis of oxygen reduction reaction (ORR). For applications in rechargeable zinc-air batteries (ZABs), achieving the necessary high catalytic efficiency of the SAs toward oxygen evolution reaction (OER) however remains a significant challenge. Here, highly asymmetrically configured Fe SAs created with N,S co-coordination and anchored on flame-roasting deposited carbon black (CB), Fe-N3S1/CB, are developed, achieving outstanding bifunctional oxygen catalytic efficiency, with an ultra-small potential gap of 0.661 V at 10 mA cm-2 (ΔE10), outperforming the (Pt/C+RuO2) composite catalyst (0.697 V). With a newly proposed binder-free composite air cathode design, the Fe-N3S1/CB based ZAB achieves an ultrahigh power density of 365.7 mW cm-2 at a current density of 511.3 mA cm-2, largely outperforming the (Pt/C+RuO2) based ZAB (225.9 mW cm-2 at 344.7 mA cm-2). Furthermore, the Fe-N3S1/CB based ZAB demonstrates excellent long-term stability, with only 8.2% decay in round-trip efficiency over 1000 (333.3 h) charge-discharge cycles at 10 mA cm-2. Density functional theory calculations elucidate that incorporation of sulfur into the coordination sphere of Fe facilitates the electrochemical dehydroxylation step for ORR and accelerates the electrochemical O2 desorption step for OER, thereby reducing the corresponding free energy differences on Fe SAs for largely enhanced catalytic efficiency.1. A large size hetero-atom element, sulfur, is introduced to create highly asymmetrically configured Fe single atoms for enhancements in catalytic efficiency toward both oxygen reduction reaction and oxygen evolution reaction, and a binder-free composite air cathode design is proposed to improve electrochemical performances of zinc-air batteries.2. An ultra-small potential gap of 0.661 V at 10 mA cm-2 (ΔE10) is achieved for the air cathode, and an ultrahigh discharge power density of 365.7 mW cm-2 at a current density of 511.3 mA cm-2 is acquired for the zinc-air battery.

Phase composition of sputter deposited tungsten thin films

Sputter deposited tungsten thin films are studied by X-ray diffraction. Two phases can be identified: α-W and β-W based on the observed (110), and (200) and (210) Bragg reflections, respectively. With increasing film thickness (50 to 200 nm), the phase composition shifts from β-W towards α-W. No influence of the base pressure (3 × 10−3 – 3 × 10−5 Pa) on the phase composition is observed. Also the influence of the argon pressure (0.3 to 0.7 Pa) is rather weak. The strongest shift towards α-W composed thin films is obtained by increasing the discharge power (50 to 250 W). This trend is further studied by energy flux measurements using a calorimetric probe. These measurements rule out a strong change of the substrate temperature, and an impact of the energy flux scaled by the deposition rate (total energy per deposited atom). Test particle Monte Carlo simulations reveal the importance of the momentum of the reflected argon neutrals on the phase composition. The maximum energy of these species is mainly defined by the discharge voltage, and is higher than the directional dependent displacement energy of W. Despite the significant correlation between phase composition and the number of displacement per deposited atom, there is a strong scatter of the phase composition. As the deposition conditions were varied in random way, changes of the target erosion profile, and the changing discharge voltage over each series are probably partially responsible for the observed scatter. This scatter is also enhanced by the long term changes in the phase composition towards the more thermodynamic stable α-W phase.

Design, Fabrication, and Testing of Small Wind Pump

The demand for energy used to pump water for irrigation has been increasing, resulting in the need for alternative renewable energy sources to reduce costs. A study was conducted to develop a small wind pump that could be used to irrigate crops. The wind pump's efficiency, discharge, and actual power generated were evaluated, and regression analysis and the coefficient of determination were used to determine the goodness of fit. Results showed that the wind pump required a minimum wind speed of 0.3 m/s produced a discharge of 0.95 L/min, while a 4.13m/s wind speed produced a water discharge of 5.45 L/min. The efficiency of the wind pump was measured using the regression equation E= - 04075(ws)² - 0.6375(ws) + 14.36, where R² = 0.6201, resulting in a maximum efficiency of 20.56% and a minimum of 5.57%. This indicates that the wind pump was efficient at low wind speeds due to the dynamic stress of the pump lift rod and a mismatch between the rotor and pump characteristics. Lastly, the net benefit of Php 25,083.61 per year was derived, with a return on investment of 33.86%, which will be paid back in 1.26 months.

Study on Plasma Surface Modification of Hydrophobic Materials

The hydrophobic materials were treated by plasma continual treater to achieve its surface modification and improve its wettability. The influences of treating time, discharge power, working gases and gas pressure on the surface modification of the materials have been investigated. The chemical states and species on the surface of materials have been investigated by some technologies such as contact angles. After plasma surface treatment, the contact angles of PTFE sharply decrease, and the alkali liquid absorption of PE increased to three times of its weight. The contact angles of silicon rubber and polyester decreased remarkably after surface modification. PTFE films were grafted with crylic acid to evaluate the ageing. The effect of vacuum ultraviolet radiation to surface modification was initially described. The results of experiment demonstrate that the better wettability of hydrophobic material can be achieved. The technique and the equipment have the promotional value for industrial application.

Modelling and Validating the Nonthermal Plasma Parameters for Producing Liquid Hydrocarbon from Solid Polyolefin Wastes

This study solved a set of equations to verify the dynamic optimal conditions of nonthermal plasma (NTP)-chemical conversion of solid polyolefin wastes into liquid petroleum hydrocarbons. Furthermore, a novel optimisation model was validated with non-linear experimental conditions to assess the quantitative relationship between the process variables responsible for the degradation rate of wastes. The central composite design (CCD) experimental design was developed based on the Response Surface Model (RSM) technique. These techniques significantly improved the model predictions because of the more-detailed electrochemical description. Experiments were conducted in an in-house-designed and -developed NTP system with advanced data acquisition schemes. Both experimental and the numerical findings exhibited a good agreement, and the results indicated that the electrical factors of NTP could significantly affect the conversion yield (Yconv%) of solid polyolefin-derived wastes to liquid hydrocarbons. Additionally, the model investigation indicated that factors such as power discharge (x1), voltage intensity (x2), and reaction retention time (RTT) (x3) significantly influenced the conversion yield. After optimisation, a maximum conversion percentage (Yconv%) of ≈93% was achieved. The findings indicated that this recommended framework could be effectively employed for scaling the plasma synergistic pyrolysis technique for generating the maximal Yconv% of plastic wastes to yield an oil. Thereafter, the analysis of variance (ANOVA) technique was applied to examine the accuracy of the developed structure in order to upgrade this laboratory-scale processes to an industrial-scale process with >95% effectiveness. The calorific value of the produced oil was seen to be from 43,570.5 J/g to 46,025.5 J/g due to changes of the arrangements of the process factors, which specified that the liquid hydrocarbons showed similar characteristics like commercial diesel in this respect.

Effects of Carbon Deposition on Deuterium Plasma-Driven Permeation Through Tungsten-Coated RAFM Steel

In steady-state operation of fusion reactors, eroded materials and contaminations, especially carbon (C), may deposit on the surface of plasma-facing components. In this work, the effects of C deposition on hydrogen isotope permeation behavior through tungsten (W)–coated reduced activation ferritic/martensitic (RAFM) steel were systematically investigated by plasma-driven permeation (PDP) measurements in the temperature range of 633 to 893 K. A C deposition layer with thickness of ~200 nm was prepared by magnetron sputtering to simulate the formation of C impurities in the first-wall area of tokamaks. The implantation depth of incident deuterium (D) ions was estimated to be <10 nm at incident energy of 114 eV. Deuterium effective diffusion coefficients (Deff’s) for W-coated RAFM steel with/without a C layer were obtained. It was found that the C layer tended to increase Deff in the low-temperature region of ~675 to 820 K. At high temperature, however, Deff was measured be lower than that without a C layer. Nevertheless, the addition of a C layer had no significant effect on Deff compared to the W coating alone with respect to bare RAFM steels. For steady-state D-PDP flux, it was found that the C layer significantly decreased D permeation flux at low temperature. But, the permeation flux difference between the samples with/without a C layer became smaller with increasing temperature, indicating that the influence of C deposition on D permeation was negligible at high temperature. Similar D-PDP behavior was detected as increasing the incident ion flux by means of increasing plasma discharge power. Surface reemission of absorbed D as well as the D concentration gradient throughout the sample was found to be influenced by C deposition; therefore, D permeation flux changed correspondingly.

A voltage-decoupled Zn-Br2 flow battery for large-scale energy storage

The flow battery represents a highly promising energy storage technology for the large-scale utilization of environmentally friendly renewable energy sources. However, the increasing discharge power of rechargeable battery results in a higher charge voltage due to its coupling relationship in charge-discharge processes, intensifying the burden of renewable energy power systems. Herein, we proposed a voltage-decoupled Na+-conducting Zn-Br2 flow battery (Ud-Na-ZBFB). Within a pH-regulation strategy, both neutral Zn/Zn2+ and alkaline Zn/Zn(OH)42− negative redox couples are integrated into one device, so as to increase discharge voltage a 0.5 V theoretical increase while remains a low charge voltage. The proof-of-concept Ud-Na-ZBFB demonstrates an unprecedented voltage characteristic, achieving a discharge voltage of up to 2.18 V while maintaining a remarkably low charge voltage of 1.78 V at a current density of 20 mA cm−2. Benefiting from the high discharge voltage, the peak power density of Ud-Na-ZBFB reaches 580 mW cm−2, nearly twice higher than the traditional ZBFB. Besides, the Ud-Na-ZBFB cycling operates for 45 h with excellent stability and resilience. With the “cycle-to-stage” operational mode, battery state of Ud-Na-ZBFB can be completely recovered after a long-term operation stage with several cycles, which electrolyte utilization efficiency of one stage is up to 41 %. This work offers a brand-new utilization pattern for high-power rechargeable battery that possesses a great potential in energy storage application scenes.