This paper examines the influence of altitude on the corona discharge and breakdown behavior of rod-plate air gaps using a two-dimensional fluid dynamics model. By simulating the discharge processes under different air pressures corresponding to various altitudes, the study provides a detailed analysis of key parameters such as electron density and electric field strength. The results demonstrate that as air pressure decreases, the voltage required for breakdown also decreases, and the discharge becomes more intense under the same voltage. The study categorizes the discharge process into three stages: no significant discharge, corona discharge, and breakdown discharge. Importantly, the presence of corona reduces the breakdown voltage below the predictions of Paschen’s law. Furthermore, the numerical results exhibit a strong correlation with Paschen’s law, confirming the model’s accuracy and reliability. These findings highlight the critical role of corona effects in influencing breakdown voltage and provide valuable theoretical insights for understanding high-altitude discharge phenomena. The outcomes also serve as a foundation for optimizing the insulation design and enhancing the performance of electrical systems operating in high-altitude environments, where reduced air density poses significant challenges to system reliability and safety.

High-power-density energy system components are subjected to coupled steady heat loads and short-duration heat shocks, for which conventional liquid cold plates provide limited transient buffering. In this study, an integrated parallel phase change material (PCM) cold plate with a topology-optimized channel (IPCP) was proposed by incorporating inter-channel metal-skeleton-enhanced PCM (MSE-PCM) for transient heat shock mitigation. A dual-objective topology optimization strategy was used to design the liquid cooling channel with balanced heat transfer enhancement and flow resistance reduction. A topology-optimized cold plate without PCM (TOCP) and a series PCM cold plate (SPCP) were used as references. A three-dimensional transient conjugate heat transfer model with phase change was established and experimentally validated. Under the 300–900–300 W transient validation condition, the peak temperature errors were 2.10% and 1.26% for the TOCP and IPCP, respectively. The IPCP introduced a limited steady-state temperature penalty, with peak temperature increasing by 2.4 K at 300 W and 4.3 K at 500 W relative to the TOCP, while the SPCP was 13.83 K hotter than the IPCP at 500 W. Under high-intensity heat shocks, the IPCP reduced peak temperature by approximately 50–67 K relative to the TOCP and by 21–47 K relative to the SPCP at 1500–2100 W. At 2100 W, the IPCP provided a delay time of 20.9 s below the 353.15 K threshold, 2.2 times that of the SPCP. These improvements originate from parallel energy partitioning between continuous liquid cooling and gradual latent heat utilization in the inter-channel PCM regions.

Sustainable ammonia synthesis under mild conditions remains a key challenge in energy conversion and fertilizer production. In this work, a perpendicular magnetic field-assisted nanosecond-pulsed PBD system was developed for efficient ammonia synthesis. By tuning key parameters (magnetic flux density, pulse voltage, N-2/H-2 ratio, and flow rate), both ammonia production rate (697.8 mu mol h(-1)) and energy efficiency (0.80 g & centerdot;kWh(-1)) were enhanced, resulting in similar to 42% higher yield and similar to 20% improved efficiency compared to the non-magnetized case. Magnetic confinement induces electron gyration and E & times; B drift, extending electron residence time and increasing both the reduced electric field and electron density. Plasma diagnostics show that the discharge is strongly non-equilibrium (T-vib >> T-rot), with the magnetic field further accentuating this by channeling input energy into vibrational excitation rather than gas heating. These effects enhance the formation of N-2 & lowast; and NH radicals, key intermediates in the surface hydrogenation process. Magnetic-field confinement intensifies plasma reactivity and energy utilization, offering a promising and scalable route for sustainable ammonia synthesis under atmospheric conditions.

The electrocatalytic reduction of nitrogen oxides (NOx) to ammonia represents a promising alternative to direct N2 reduction but is often limited by low reaction rates, poor selectivity, and severe competition from hydrogen evolution under dilute feed conditions. Here, we report a plasma-enabled electrocatalytic strategy for efficient NOx-to-NH3 conversion using an electronically engineered Cu-N-P catalyst. A rotating gliding arc plasma converts air into reactive NOx species, providing a continuous and controllable feed for downstream electrochemical reduction. The Cu-N-P catalyst achieves an ammonia production rate of 2.36 mmol h-1 cm-2 with nearly 100% Faradaic efficiency at -0.575 V versus RHE and maintains stable operation for over 125 h under plasma-derived NOx conditions. Compared with unmodified Cu, the N, P co-doped catalyst promotes selective NOx adsorption and accelerates the hydrogenation of key intermediates while suppressing parasitic hydrogen evolution. Spectroscopic characterizations and theoretical analysis reveal that electronic structure modulation facilitates efficient NOx utilization and favorable hydrogenation kinetics. This work establishes an effective catalytic pathway for NOx-to-ammonia conversion under plasma-assisted conditions, providing insights into catalyst design for coupled plasma-electrochemical nitrogen conversion systems.

To address the challenges of insulation stress on the secondary winding and low energy efficiency during the miniaturization of Tesla transformers, this article proposes a triple-resonant transformer circuit topology that incorporates a high-voltage diode. Based on the traditional dual-resonant topology, this circuit incorporates a high-voltage diode to introduce an additional self-resonance stage, thereby achieving voltage division that reduces insulation stress on the secondary winding and improves energy efficiency. A prototype of a compact 100-kV high-voltage, high-frequency nanosecond pulse generator has been developed, and by embedding the secondary high-voltage capacitor and high-voltage diode directly within the transformer, the system size is further reduced. The volume of the pulse generator is only 25 & times;17 & times;27 cm (11.4 L). Detailed testing of each module showed that the pulse amplitude before sharpening reaches approximately 116 kV, which is 1.67 times the maximum voltage sustained by the Tesla secondary winding. After sharpening by a spark gap switch (SGS), a pulse with an amplitude of 100 kV, a rise time of 8 ns, and a full width at half maximum (FWHM) of 190 ns was generated across a 1.25-k Omega load. The maximum repetition rate reached 100 Hz, with a peak power density of 0.7 MW/L. This design successfully achieves the miniaturization goal while reducing insulation stress on the secondary winding by 40% and increasing efficiency to 75%.

The pulsed and sinusoidal barrier discharges in air have been studied. Plane-to-plane and pin‑to‑plane electrode configurations implementing volume and surface barrier discharges have been used. Experimental results on the influence of the electric charge deposited by streamers or an external source on the barrier surface, on the voltage at which streamers are generated and on their configuration are presented. In the case of the surface barrier discharge, results are presented for two situations: in the absence and in the presence of a strong magnetic field perpendicular to the surface streamer current. A “memory” effect is observed for positive streamers formed in adjacent half-periods of the sinusoidal voltage.

Electrochemical nitrogen reduction under ambient conditions is constrained by the kinetic inertness of N2 and competition from the hydrogen evolution reaction. Here, we report an integrated plasma-electrolysis membrane-electrode assembly that couples a microstructured nonthermal surface discharge directly to a gas-diffusion cathode, enabling in situ generation and delivery of vibrationally excited N2, N2(ν), to the electrocatalytic interface. Among 14 metal catalysts screened, Ag provided the best balance of activity and selectivity, achieving an NH3 production rate of 7.7 ± 0.8 nmol s-1 cm-2 with an electrochemical Faradaic efficiency of 86 ± 14% at -0.54 V versus RHE under atmospheric pressure and room temperature. Plasma/electrolysis on-off controls and 15N2 isotope-labeling experiments establish that NH3 formation requires simultaneous plasma activation and electrochemical polarization and originates from the supplied N2. Plasma-kinetic modeling indicates strong vibrational excitation in the discharge, with a calculated effective vibrational temperature of approximately 4300 K and 11.8% of N2 occupying levels (ν = 4-8). Transport modeling further suggests that these comparatively long-lived excited states persist to the membrane-catalyst region. In situ Raman spectroscopy reveals N-N-containing surface intermediates only during coupled operation, while density functional theory shows that vibrational excitation lowers the free-energy requirement for the initial hydrogenation of N2 to *NNH and shifts the rate-determining step in a catalyst-dependent manner. These findings establish vibrational-state engineering as a strategy for coupling non-equilibrium molecular activation with electrocatalysis for distributed ammonia synthesis under ambient conditions.

Plasma-catalytic ammonia synthesis is one of the most promising technologies for decentralized ammonia synthesis under mild conditions. Although optimizing the catalyst and reaction conditions can increase both the NH3 concentration and energy efficiency to more than 3000 ppm and 1.84 g NH3/kWh, respectively, there is still a considerable gap from industrial application. Exploring the reasons and limitations of plasma-catalytic ammonia synthesis is crucial for further improving the concentration and energy efficiency of ammonia synthesis. In this paper, Ni/Al2O3 catalysts with different Ni loading are employed to investigate the ammonia synthesis under several discharge conditions. Combining the results of the conversion experiments and the characterization of the catalyst, we show that the activity of the catalyst is related to its surface morphology and the dispersion of Ni. The zero-dimensional (0D) reaction kinetics model reveals that the adsorption and dissociation of N2(v) on the catalyst surface provides an available reaction path, thus increasing the NH3 concentration and energy efficiency. The results uncover that increasing the proportion of high level N2(v) may be the key to affecting the catalytic reaction performance.

Zearalenone (ZEN) poses a major risk to grain safety and consumer health. This study compared ZEN degradation by gas-phase and liquid-phase surface dielectric barrier discharge (SDBD) plasma. Liquid-phase treatment achieved 98.1% degradation at 25 W within 3 min, whereas gas-phase treatment reached 95.9% at 25 W within 9 min. Gas-phase degradation followed first-order kinetics, while liquid-phase degradation followed zero-order kinetics. At removal above 90%, the liquid-phase treatment also delivered a higher energy yield. O3 was the dominant species in gas-phase degradation, whereas reactive species in liquid-phase degradation were 1O2 and ·OH. UPLC-MS demonstrated that both liquid and gas-phase treatments attacked the C11C12 bond, phenolic-OH groups, and C3-methyl group, with additional cleavage of the C1 ester group in the liquid phase. Toxicity simulations and mouse colon histology indicated reduced acute and chronic toxicity after SDBD plasma treatment. These findings support SDBD plasma as an efficient detoxification strategy for grain-processing applications and food safety protection.

Ammonia (NH3) is emerging as a carbon-free energy carrier and chemical feedstock essential for the clean energy transition. Herein, we present an integrated plasma-electrocatalytic tandem system for sustainable ammonia synthesis directly from air and water. In this process, a rotating gliding arc plasma activates atmospheric nitrogen and oxygen to generate NOx intermediates, which are subsequently electrochemically reduced to ammonia on a Cu2O-based catalyst. By dynamically balancing plasma-derived NOx generation (67 mM within 15 min) and electrocatalytic consumption, a pulsed NOx replenishment strategy is established to maintain stable NOx concentrations (65-70 mM) during prolonged operation. This approach achieves a high ammonia yield rate of 0.648 mmol h-1 cm-2 and a faradaic efficiency of 86.97%, sustaining continuous performance without depletion. The study demonstrates a scalable and energy-efficient route for green ammonia synthesis, offering a promising pathway for decentralized, renewable-powered nitrogen fixation.

This review prensents plasma–electrocatalytic tandem ammonia synthesis, covering nitrogen activation, NO x management, NH 3 formation, reactor integration, and pathways toward scalable green ammonia.

Decentralized, sustainable ammonia production could have an immense global impact. Here we describe an electrolytic approach to synthesizing ammonia directly from air and water under ambient conditions, which could be developed and optimized toward this goal. The system integrates a gliding arc discharge plasma reactor for generating NO x from air with a membrane electrode assembly reactor for the electrochemical reduction of NO x - to ammonia, enhancing both the efficiency and scalability of the process. Furthermore, the plasma-generated NO x feedstock can be substituted with NO x derived from industrial waste, further extending the potential of this system. In this Protocol, we describe the fundamental principles of this plasma-electrochemical nitrogen reduction reaction (PE-N2RR) system and provide advice for experimental standardization, operational mechanisms and data analysis methods. The procedure starts with the synthesis of the catalyst-a La1.5Sr0.5Ni0.5Fe0.5O4 perovskite oxide-at either laboratory or industrial scale. This catalyst is sufficiently stable to enable the NO x - RR to continuously work under strongly acidic conditions. We highlight the key operating parameters that are necessary for plasma-based NO x production and electrochemical NO x - reduction reaction systems. This information and framework can be used to optimize and streamline the entire PE-N2RR system. A moderate level of expertise in electrochemistry, plasma systems and catalyst synthesis is recommended to ensure successful execution. The setup of the entire PE-N2RR system, from catalyst synthesis to the configuration of plasma and electrochemical, is estimated to take 72 h. The full reaction operation test requires 200 h, whereas in situ electrochemical characterizations take 3 h.

The in-situ resource utilization (ISRU) of the CO2-rich Martian atmosphere is crucial for supporting future human exploration and sustained presence on Mars. This work demonstrates the application of a direct current (DC) glow discharge plasma for the direct dissociation of CO2 into O-2 under simulated Martian conditions. The effects of key operational parameters including gas pressure, discharge current, and gas composition were systematically investigated in terms of discharge characteristics and CO2 dissociation performance. Results demonstrate that CO2 dissociation is highly sensitive to discharge polarity and pressure, with negative DC polarity proving particularly effective at low pressures. Optical emission spectroscopy identified distinct peaks for CO2+, CO, and atomic oxygen, confirming electron-impact dissociation. The addition of 10% Ar markedly intensified the CO2+ emission, indicative of enhanced ionization via Penning processes. In contrast, the introduction of N-2 generated emission bands from excited N-2 species, which promoted CO2 dissociation through energy transfer; however, this process was less efficient due to competitive energy absorption by N-2. BOLSIG+ simulations corroborated that Ar significantly increases the average electron energy and strengthens the high-energy tail of the electron energy distribution function, thereby boosting CO2 conversion. At a specific energy input of 0.5 J & centerdot; ml(-1), the addition of 10% Ar and 10% N-2 enhanced the CO2 conversion by 16% and 12%, respectively. These findings provide valuable insights for developing scalable plasma-based ISRU systems for oxygen and fuel production on Mars, which are essential for future crewed missions.

Electrochemical nitrogen reduction under ambient conditions is constrained by the kinetic inertness of N2 and competition from the hydrogen evolution reaction. Here, we report an integrated plasma-electrolysis membrane-electrode assembly that couples a microstructured nonthermal surface discharge directly to a gas-diffusion cathode, enabling in situ generation and delivery of vibrationally excited N2, N2(nu), to the electrocatalytic interface. Among 14 metal catalysts screened, Ag provided the best balance of activity and selectivity, achieving an NH3 production rate of 7.7 +/- 0.8 nmol s-1 cm-2 with an electrochemical Faradaic efficiency of 86 +/- 14% at -0.54 V versus RHE under atmospheric pressure and room temperature. Plasma/electrolysis on-off controls and 15N2 isotope-labeling experiments establish that NH3 formation requires simultaneous plasma activation and electrochemical polarization and originates from the supplied N2. Plasma-kinetic modeling indicates strong vibrational excitation in the discharge, with a calculated effective vibrational temperature of approximately 4300 K and 11.8% of N2 occupying levels (nu = 4-8). Transport modeling further suggests that these comparatively long-lived excited states persist to the membrane-catalyst region. In situ Raman spectroscopy reveals N-N-containing surface intermediates only during coupled operation, while density functional theory shows that vibrational excitation lowers the free-energy requirement for the initial hydrogenation of N2 to *NNH and shifts the rate-determining step in a catalyst-dependent manner. These findings establish vibrational-state engineering as a strategy for coupling non-equilibrium molecular activation with electrocatalysis for distributed ammonia synthesis under ambient conditions.

The plasma-catalytic dry reforming of methane (DRM) emerges as a promising strategy for concurrently mitigating carbon emissions and producing renewable energy resources. The conventional plasma-catalytic DRM approaches, nonetheless, often result in the production of lower-value syngas and exhibit limited selectivity towards higher-value liquid products, particularly alcohols. Here we developed a plasma-catalytic DRM system integrated with the cobalt-supported gamma-Al2O3 catalysts (CoOx/Al2O3) for enhancing the synthesized alcohol selectivity. Investigations into various metal-supported catalysts, cobalt loadings, cobalt oxidation states and calcination temperatures indicated that a 5 % cobalt-loaded catalyst calcined at 500 degrees C could achieve an optimized alcohol selectivity of 37.2 %, accounting for 90.7 % of the oxygenates. Comparative analyses between physically mixed CoOx-Al2O3 catalysts and chemically mixed CoOx/Al2O3, complemented by in situ plasmacoupled Fourier Transform Infrared spectroscopy and density functional theory calculations, highlighted the critical influence of oxide-oxide interactions in enhancing alcohol yield. These findings highlight the importance of oxide catalysts in efficient alcohol production in plasma-catalytic DRM, offering a sustainable approach that balances environmental benefits with the generation of valuable energy resources.

Given its significant environmental and economic impact, substantial research has been dedicated to improving the Haber–Bosch process. Leveraging the advantages of renewable energy sources and sustainable feedstocks, plasma catalysis is emerging as a promising green technology for small-scale, onsite nitrogen (N₂) fixation. However, current plasma-catalysis applications for nitrogen fixation face several challenges. These include high energy consumption for hydrogen (H2) production prior to ammonia synthesis, low energy efficiency, and a limited understanding of the underlying mechanisms. In this study, we compare two green chemical pathways for plasma catalysis in NH3 and NOx production and their effective storage in water from a plasma chemistry modeling perspective. Our model incorporates both electron and vibrational kinetics, along with updated surface reactions based on Density Functional Theory (DFT) calculations. These calculations consider catalytic ruthenium (Ru) on MgO supports and non-catalytic SiO2 as a reference for ammonia synthesis and titanium dioxide (TiO2) for NOx synthesis. We will evaluate and discuss key intermediates and pathways for producing high-density NH3 and NOx, and suggest opportunities for further improvement.

Low-temperature plasma is widely used in thin-film deposition, circuit etching, material surface modification, and other applications in which plasma parameters can significantly affect the outcomes. Compared to single-source excitation, dual-source excitation can enhance the efficiency of energy utilization and expand the range of parameter variations. A low-pressure tube filled with a mixture of 95% Ar and 5% N2 was developed to study the plasma properties under DC excitation and dual-source excitation with DC superimposed nanosecond pulse. The effects of different pulse amplitudes and pulse widths on the plasma properties were explored. The experimental results show that the superposition of pulses can enhance the electron density in the afterglow phase, and the enhancement of electron density in the afterglow phase is more sensitive to the pulse amplitude. The electron density can be maintained at a high level after the pulse ends, with a maximum value reaching 1017 m-3. In addition, the electron density in plasma under dual-source excitation can be two orders of magnitude higher than under single DC excitation, while the gas temperature decreases by approximately 40 K, thereby increasing the range of plasma parameters variations.

AbstractThe physical process of microsecond pulsed discharge in transformer oil is the foundation for studying the initial mechanics of faults in ultra‐high voltage transformers. However, the microsecond‐scale electrohydraulic effect in transformer oil has not been investigated yet. In this paper, the shock wave and bubble generated by microsecond pulsed discharge in transformer oil between needle‐needle electrodes are studied using a Schlieren system with a high‐speed camera. The results show that the discharge channel in the 0.1 mm oil gap forms in 9.50 µs when the streamer and the first shock wave are observed. The bubble between electrodes expands in the subsequent 218.50 µs. Then, the bubble collapses when the second shock wave is observed. The velocities of the first and the second shock wave are 1388.16 and 1465.46 m/s, respectively. With the gap distance increase, all the breakdown voltage, the discharge energy, and the ratio of the mechanical energy to total energy increase, the breakdown current, the acceleration of the container wall, and the velocity of the shock wave decrease. It can be concluded that the first shock wave is generated by the streamer of microsecond pulsed discharge and the second shock wave is induced by the rapid density change due to the bubble collapsing.

Discharge plasma presents a promising approach for converting heavy oil into light hydrocarbons under room temperature and atmospheric pressure. Among various techniques, repetitive pulsed discharge plasma is preferred for its potential to improve energy efficiency, however the decomposition characteristics and gaseous production pathways of long-chain hydrocarbons remain insufficiently understood. In this study, the decomposed products and process of mineral transformer oil under repetitively pulsed spark discharge in the liquid phase are analyzed by gas chromatography (GC) and optical emission spectroscopy (OES). Experiment results reveal that the proportion of H2 gas production decreases, while that of C2H2 increases with the prolonged reaction time. Besides, the production of C2H2 is significantly higher at a pulse frequency of 1000 Hz compared to 10 Hz. OES analysis further shows that the electron density decreases as the repetitive pulse frequency increases, a trend that contrasts with prior observations of heavy oil cracking in gas and liquid-gas reaction systems. Despite the reduced energy per pulse at higher frequencies, the total number of breakdown events over the same reaction duration is larger, contributing to enhanced reaction outcomes. These experimental findings are confirmed by plasma kinetics and molecular dynamics simulation, which identified a continuous dehydrogenation process involving H radical reactions with C2H4 as the primary pathway for C2H2 and H2 production. The study demonstrates the feasibility of C2-oriented conversion through the decomposition of heavy oil decomposition under spark discharge, with adjustments to repetitive pulse parameters offering a promising avenue for optimization.