Optimizing Corona Electrode Geometry: A Comparative Electric Field Analysis

Influence of Electrode Surface State on Air Gap Breakdown Characteristics at the Micrometer Scale

To investigate the influence of electrode surface roughness on gas discharge characteristics under micro-gap conditions, direct-current breakdown experiments were carried out in atmospheric air using a nano-positioning system. Breakdown tests were conducted for five metal electrodes over the electrode gap distances from 1 to 10 µm, and for one metal with different surface roughness levels over the electrode gap distances from 1 to 20 µm. Meanwhile, the electric field intensity distribution of aluminum electrodes (cathode) with different surface roughness values was simulated using Maxwell electromagnetic field simulation software. The experimental results show that, in the electrode gap distances from 1 to 5 µm, different metal electrodes exhibit different degrees of deviation from the Paschen curve, all of which are related to the work function. At the same electrode gap distance, the rougher the electrode surface, the larger the field enhancement factor β and the lower the breakdown voltage. Analysis indicates that surface protrusions cause local electric field intensification, allowing the field strength to reach the critical condition for field electron emission, thereby reducing the breakdown voltage. In the electrode gap distances from 10 to 20 µm, electrode surface roughness leads to a multiplication of the effective electron emission from the cathode surface, thus enhancing the surface electron emission process. Therefore, in the design of microelectronic devices, reducing electrode surface roughness and selecting metal electrode materials with higher work functions can effectively improve gas breakdown characteristics under small-gap conditions and optimize the insulation protection of microelectronic devices.

Effect of Magnetic Field on Arrayed Corona Discharge

Corona discharge has been extensively adopted for plasma generation, but its practical application is constrained by discharge uniformity and operational stability. In this study, numerical simulations are performed to explore the enhancement mechanism of external magnetic fields on corona discharge, with a focus on the influences of coil configuration, excitation current magnitude, and needle electrode spacing. The simulation results reveal that Helmholtz coils achieve optimal electric field enhancement by eliminating axial magnetic field gradients. Nevertheless, excessively high excitation current will trigger the transition of discharge mode from diffuse corona to arc discharge. Additionally, an optimal needle electrode spacing is determined to strike a balance between electric field intensity and spatial uniformity. The outcomes of this study provide a solid theoretical foundation for the design and optimization of magnetic field-assisted corona discharge systems, which hold promising prospects for environmental treatment and material processing applications.

A bulk-surface continuum model for voltage propagation in dielectric materials

The determination of transient changes in bulk resistance under applied electric fields is essential for evaluating surface conductivity in dielectric materials. Theoretical approaches can provide valuable insights into voltage propagation by analyzing temporal variations in the bulk response. However, due to the lack of a detailed and accurate understanding of the mechanisms governing resistance changes under external electric fields, the applicability of existing models remains limited. In this work, an improved model based on Rall’s biophysical-mathematical framework for neurons is presented and experimentally validated. Hydroxyapatite (HA), the primary mineral constituent of human bone and teeth, has attracted considerable interest as a pseudocapacitive electrode material for supercapacitors owing to its structural stability, abundant electroactive sites, and favorable ion transport properties, making it an attractive model system for evaluating the proposed approach. HA was subjected to thermal and electrical stimulation in the 250–1500 V range at 1000 °C. The comparative analysis between the theoretical model and experimental results demonstrates that our theoretical framework provides a robust basis for predicting electric current behavior in HA under externally applied voltages. Its applicability remains valid under real-world conditions, including the effects of diffusion and geometric factors. The proposed model demonstrates superior performance compared with recently reported deterministic and stochastic dielectric models.

Calculating Electric Flux of Non-Uniform Electric Fields for Corona Discharge of Freon Gas

A novel theoretical approach for investgating the mechanism of non-uniform charge deposition on dielectric surface induced by secondary electron avalanche in vacuum flashover

In previous theoretical studies of vacuum surface flashover, zero-dimensional models were typically employed. It was assumed that only the applied electric field existed tangentially along the insulator surface, and the positive charges deposited on the dielectric surface were uniformly distributed along the tangential direction. However, experimental observations have revealed that the deposited charges on the dielectric surface exhibit a non-uniform distribution. By employing the concept of image charges, this paper proposes a novel theoretical approach that effectively explains the mechanism responsible for this non-uniform distribution of deposited charges. Furthermore, a theoretical criterion is proposed, suggesting that the maximum electric field strength near the cathode tends to be the same during flashover breakdown for the same insulating material. Based on this, a rapid calculation and scaling model for the flashover breakdown voltage of insulators with different lengths has been developed, which can provide fast predictive assessment for engineering applications. Comparisons with particle-in-cell (PIC) simulations and experimental results verify the correctness and reliability of the proposed theoretical method and rapid calculation model.

Investigation into nonuniformity of potential distribution in electrodes and its influence on inner resistance by application of mathematical methods

Discussed are one-dimensional and two-dimensional cases of potential distribution in electrode. It is demonstrated that if the rate of current formation in each point of electrode was (according to Faraday's law-) proportional to transferred electrical charge as well as to deviation of potential from equilibrium potential, then the problem of potential determination brings to equation solution in the form: Δφ = k2φ , where Δ – Laplace operator; φ – potential deviation from equilibrium; k – a constant dependent on electrode parameters. The analysis of solutions obtained demonstrates that the design features of current leads produce unconformity of current and potential distribution in electrodes. As a result, the current-formatting processes over the electrode area occur with different rate The rate of charge/discharge processes in sections adjacent to current leads is higher than in remote sections and periphery of electrode. Calculation indicates that the increase of potential nonconformity in electrodes results in increase of inner resistive component.