This study investigates the energy transfer characteristics of arc discharge in transformer oil under power frequency AC voltage, focusing on bubble dynamic evolution and pressure wave propagation. An experimental platform with a high-speed schlieren system, voltage-current measurement module, and spectrometer was built. Breakdown experiments were conducted at pin-pin electrode gaps of 1, 2, and 3 mm to observe bubble development and pressure wave properties. The results show that bubbles undergo multiple expansion-contraction pulsations during discharge; their diameter and velocity increase with gap size, with a maximum velocity of 165.39 m/s. Pressure wave velocity ranges from 1.22 km/s to 1.37 km/s and also rises with gap size, reflecting the nonlinear correlation between bubble dynamics and oil gap dimensions. This study establishes the energy transfer path of arc discharge in oil and reveals the coupling mechanism between bubble evolution and pressure wave propagation, providing a theoretical basis for insulation fault diagnosis and protection of transformers.

Non-thermal plasma coupled with catalysts offers a promising route to improve ammonia-to-hydrogen conversion efficiency. This study integrates plasma discharge with morphology-controlled CeO2 nanocrystals (fiber, cuboids-S, cuboids-L, nano-rod, and pyramid) to enhance ammonia decomposition. Among them, CeO2 fiber achieves outstanding ammonia conversion exceeding 99.9% (SIE = 19.8 kJ L-1) without metal additives or external heating, while also demonstrating remarkable long-term stability. Through combined microscopic, electrical, and Mass Spectrometry-based transient analysis, it is revealed that the fibrous CeO2 structure increases the surface Ce3+ and oxygen vacancy concentration and provides balanced NH3 adsorption, boosting catalytic activity. Additionally, its favorable dielectric properties enhance plasma discharge and plasma-catalyst interactions. These results demonstrate that tuning catalyst nanostructure is an effective alternative to noble metal doping for efficient plasma-driven catalysis.

Compact and lightweight modern electronics suffering from harsh service environments result in urgent demands for the miniaturization and robustness of energy-storage film capacitors and ever-thinner dielectric films. However, the energy storage of ultrathin dielectric films is limited by the breakdown of the Helgee-Bjellheim scale law in the sub-10 & micro;m range, and no interface-free method currently exists to boost their performance for industrial-scale implementation. This work proposes monochromatic and soft ultra-violet (UV) irradiation to increase the breakdown strength of 2.4 & micro;m biaxially-oriented polypropylene (BOPP) films from 374 to 484 V & micro;m(-1) (by 29.4%), their discharge energy density to a competitive 2.41 J cm(-3) (by 53%) with an impressive charge-discharge efficiency of 96% at 125 degrees C, and the charge-discharge cycle-lifetime by more than 2.5 times. In situ electron spin resonance spectra illustrate that UV-activated peroxyl radicals crosslink BOPP and form deep traps suppressing charge carrier migration, without decreasing its bandgap even under a strong electric field. However, current production lines using corona treatment introduce harmful C=O bonds, significantly deteriorating BOPP's bandgap. This work demonstrates a one-step and high-throughput UV irradiation method matching the existing drafting-roll production line of ultrathin capacitor films to promote their energy storage.

This study explores the cracking gas production characteristics of transformer oil under power-frequency AC voltage. The experiment used a needle-plate electrode structure to generate discharge in mineral oil. Gas chromatography was used to analyze the composition of gas products, and emission spectrum technology was used to analyze plasma characteristics. Results show that at a single-cycle discharge energy of 0.25 J and 0.35 J, the main gas products are H₂, C₂H₂, C₂H₄ and C₂H₆. Among them, the proportions of C₂H₂ and H₂ increase significantly with higher discharge energy. Spectral analysis shows that power-frequency discharge is more conducive to C₂ formation, which further confirms its high-temperature cracking characteristics. The study also calculated electron density and temperature using the Stark broadening method and Wien displacement method. This work provides a theoretical basis and experimental data for transformer fault diagnosis technology.

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.

The withstand voltage performance of the metallized film is the key factor determining the reliability of the capacitor. This study investigates the influence of electrode contact configuration on the dielectric breakdown characteristics of metallized biaxially oriented polypropylene (BOPP) films. Experiments are conducted using two distinct setups: one with the film’s metal layer contacting a high-voltage electrode and the other with it contacting a ground electrode. The results demonstrate a significant configuration-dependent effect. When the metal layer contacts the high-voltage electrode, the film exhibits a lower average breakdown strength of approximately 386.7 V/μm, accompanied by pronounced self-healing discharges and electrode clearing. In contrast, contact with the ground electrode yields a higher average breakdown strength of 517.1 V/μm without observable self-healing, leading to a smaller breakdown area. Weibull analysis further indicates that the former configuration has a lower characteristic breakdown strength but higher data reliability. The disparity is attributed to a higher concentration of shallow traps and insulation weak points at the BOPP/metal interface under high-voltage contact, which facilitate charge injection and promote breakdown. These findings provide critical insights for optimizing the insulation design and electrode configuration of metallized film capacitors in high-voltage applications.

Plasma-catalytic hydrogenation of CO2 to methanol presents a promising strategy for mitigating carbon emissions and utilizing renewable hydrogen. However, limited studies have investigated the influence of catalyst hydrophobicity, since CO2+H2 reactions inherently generate water, which causes inevitable competitive adsorption between CH3OH and H2O molecules. Here we designed a series of Co-Al mixed oxides (Co3O4/Al2O3) with varying polytetrafluoroethylene (PTFE) doping ratios by a direct physical mixing strategy to enhance the CH3OH yield. Structural analyses confirmed PTFE's interfacial incorporation and its modification of catalysts' hydrophobicity by enhancing surface roughness and reducing surface energy. The catalytic performances were closely related to the mass ratio of Co3O4/Al2O3 to PTFE. Specifically, a maximum CO2 conversion of 17.5 % was achieved over the 2CoAlO-P (catalyst:PTFE mass ratio = 2:1) under ambient conditions (25 degrees C, 0.1 MPa), together with a CH3OH selectivity of 66.2 % and a high CH3OH yield of 11.6 %. The comparative zero-dimensional numerical simulations combined with in-situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) revealed the crucial role of PTFE doping in enhancing CH3OH formation. The PTFE dopant effectively prevented H2O product from occupying Co3O4 active sites and then accelerated the transformation process of surface carbonates. This work highlights the pivotal role of surface hydrophobicity of the catalysts in plasma-catalysis, thereby circumventing the traditional paradigm of designing overly complex nanocatalysts.

Atmospheric bioaerosol inactivation is a critical research priority for controlling the transmission of airborne pathogens. However, conventional disinfection systems often exhibit slow bactericidal kinetics and lack quantitative frameworks to characterize the precise dose–response relationship. To address these limitations, we proposed a decoupled composite disinfection system (DCD-System) integrating non-thermal plasma (NTP), ultraviolet (UV) radiation, and photocatalysis. This study provided two primary contributions: 1) the introduction of a time-integrated dose–survival model to accurately quantify inactivation kinetics, and 2) the evaluation of an integrated oxidation framework that accelerated irreversible ultrastructural damage. The plasma module of the DCD-System featured a localized intense electric field of 2.2 × 107 V/m and an electron density of 1.9 × 1012 cm-3, and generated reactive oxygen species (ROS, including O2- and 1O2). Evaluations using Staphylococcus albus in a 20 m3 chamber demonstrated that the DCD-System achieved a log reduction > 4.0 within a 15 min effective dose period, significantly outperforming standalone modules. Furthermore, the DCD-System exhibited a lower median inhibitory dose (ID50), indicating that combined exposure to plasma-generated ROS and UV radiation accelerated cell membrane permeability and intracellular protein leakage.

Low-temperature plasma (LTP) assisted catalysis enables not only the conversion of CO2 into liquid products under mild conditions, but also significant enhancement in catalytic efficiency through plasma-catalyst synergy. In this study, an efficient plasma synergistic catalytic system was developed. By incorporating amino functional groups and active metals into metal-organic frameworks (MOFs) and coupling it with LTP, the system not only significantly improved the reaction efficiency but also successfully directed the product selectivity by regulating the key reaction intermediates. After regulation, the catalyst demonstrated a performance with 27.1% CH4 conversion, 22.7% CO2 conversion, and 53.9% selectivity toward liquid products. In the liquid products, the total selectivity toward alcohols reached 39%, with alcohols thus accounting for 72.3% of them. Notably, C3 alcohols with a selectivity of 2.5% were detected for the first time. Using plasma-coupled in situ infrared spectroscopy, the control mechanism of the reaction pathway was revealed. This mechanism, analogous to a "molecular shunt switch", regulated the transformation between the main reaction paths. Specifically, the initial pathway involved the gradual hydrogenation of CO to alcohols. However, upon the introduction of -NH2 groups, the pathway shifted to the coupling of OH and CHx. The subsequent addition of Co reversed this shift, causing the CO hydrogenation pathway to re-dominate. Furthermore, Co and -NH2 were found to regulate the formation and consumption of CH3O. This control mechanism provides insights and guidance for the design of new catalysts.

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%.

Trifluoromethanesulphonyl fluoride (CF3SO2F) has emerged as a promising sulfur hexafluoride (SF6) alternative gas, yet its insulation characteristic under nonuniform electric fields is unclear. This article investigates the breakdown and surface flashover properties of CF3SO2F/N-2 mixtures under power-frequency ac voltages in nonuniform fields, with comparative analysis against SF6 under identical conditions. The results demonstrate that increased pressure enhances insulation strength for all gas mixtures. Under extremely nonuniform electric fields, the breakdown voltage of SF6 exhibits a significant saturation trend with increasing gas pressure, whereas the saturation phenomenon is relatively less pronounced in CF3SO2F/N-2 mixtures. For surface flashover, the saturation behavior of CF3SO2F/N-2 mixtures with rising pressure is more marked compared to SF6. The CF3SO2F/N-2 mixture approaches the gap insulation performance of SF6 more readily (requiring only about 0.2-MPa gas pressure), but shows a greater discrepancy in surface insulation performance (needing approximately 0.4-MPa gas pressure). Post-flashover characterization via Fourier transform infrared spectroscopy (FTIR), scanning electron microscope, and energy-dispersive spectroscopy reveals flashovers in SF6 leads to extensive ribbon-like discharge channels with lots of erosions on the epoxy resin surface, while flashovers in CF3SO2F/N-2 mixtures produce only discrete spot-like damage with relatively few erosions.

Cobalt-free nickel-rich layered cathodes are promising for high-energy lithium-ion batteries, but suffer from severe structural and performance degradation during cycling. However, how cobalt regulates the temporal evolution and coupling of these degradation processes remains insufficiently understood. Herein, the degradation evolution of cobalt-free nickel-rich layered cathodes (using LiNi0.75Mn0.25O2 cathode as examples) is investigated via multiscale characterization techniques. Rather than identifying individual degradation modes, this work reveals how Co regulates their temporal evolution and coupling. LiNi0.75Mn0.25O2 exhibits a higher initial degree of Li/Ni mixing and larger irreversible lattice evolution after the first cycle. After 200 cycles, the degree of Li/Ni mixing increases from 2.62% to 7.32% in LNMO, compared with 1.12% to 3.12% in LiNi0.75Co0.05Mn0.2O2, accompanied by more pronounced particle cracking, interfacial degradation, and thermal reconstruction. These results demonstrate that Co incorporation delays the transition from gradual structural aging to accelerated coupled degradation within the nickel-rich cathode system.

Metallized biaxially oriented polypropylene (M-BOPP) films are widely used as dielectric components in electrical power and pulsed power systems, where they frequently encounter electrical stresses from nanosecond to millisecond pulses. A detailed investigation into their self-healing behavior across this broad timescale is crucial for improving the operational reliability and service life of these devices under practical working conditions. Focusing on practical performance under varied electrical conditions, this research systematically explores the effects of pulse parameters (rise time, width, and amplitude) on the self-healing performance of M-BOPP film. The self-healing mechanism is uncovered by analyzing voltage/current waveforms, peak voltage, and injected energy. It was found that the self-healing time (1-2 mu s) is intrinsic to the material and independent of pulse conditions, whereas the peak voltage correlates with rise time through a power law and with pulse width logarithmically. The energy injected during self-healing rises with increasing pulse parameters and directly links to the extent of damage in the dielectric and metallized layer. Microscopic evidence indicates that successful selfhealing creates an insulating zone resembling a crater, whereas failure stems from some permanent conductive paths. These findings indicate that the increase in energy injection resulting from changes in pulse parameters is a key factor affecting dielectric endurance and structural changes. This provides the crucial experimental support and practical strategies for improving the operational reliability of M-BOPP films.

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.

Buffer layer ablation is one of critical failures in high-voltage cross-linked polyethylene (XLPE) cables, which poses a significant challenge to power system reliability. As existing detection methods exhibit limitations, it is critical to develop a reliable technique for identifying latent buffer layer defects in active service cables. A full-scale experimental platform was established to investigate the discharge and ablation evolution of buffer layer under both dry and damp conditions. A key innovation involves modifying the electrode design on the cable's outer semi-conducting layer to achieve uniform voltage across the buffer layer, which can avoid localized current concentration and realize the simulation of different buffer layer defects. In the experiment of buffer layer defect simulation, multiple parameters were measured to track the evolution of buffer layer degradation and extract characteristic parameters for field monitoring, including characteristic gas, equivalent resistance, and discharge current. Results show that buffer layer discharge and ablation generate CO, CO2, H2, and hydrocarbon gases. Dry conditions led to “self-healing” breakdown with rising resistance, while damp conditions caused severe current concentration and high H2 production. The gas concentration and species are correlated with the defect type and severity of buffer layer. The gas and electrical parameters can provide the early warning for state detection of high voltage cable buffer layer.

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.

Ammonia is a promising hydrogen carrier, but its catalytic dissociation typically requires high temperatures and costly metal-based catalysts. This study explores an energy-efficient strategy for hydrogen production by dissociating ammonia under ambient conditions using a nature-inspired cordierite catalyst activated by an electric field. The metal-free catalyst system achieved a record-high ammonia conversion rate exceeding 99.99% and an energy efficiency of 1.7 mol gcat−1 kWh−1 without external heating. Through comprehensive structural, electrical, and spectroscopic analyses, the work reveals that optimizing the crystal structure and electronic properties of the cordierite enhances discharge dynamics and promotes efficient electron-induced ammonia dissociation. 15NH3 isotope labeling experiments combined with kinetic modeling further show that tuning the catalyst’s microstructure and surface characteristics regulates the rate-determining steps and boosts overall reaction efficiency. This approach demonstrates the potential of electric-field-assisted catalysis using Earth-abundant materials and offers a new direction for designing scalable, cost-effective systems for sustainable hydrogen production.

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.