Conic Cross-Sectional Electrodes and Their Influence on Negative Corona Discharge and Trichel Pulse Characteristics

This paper computationally investigates the influence of different needle electrodes with conic cross-sections on negative corona discharge. Specifically, the study focuses on Trichel current pulses, a vital characteristic of gas discharge plasma under applied negative DC voltage. The needle cathodes encompass hyperbolic, parabolic, and elliptic shapes, with varying eccentricities while maintaining a constant radius of curvature. The magnitude, frequency, and temporal attributes of Trichel pulses are comparatively and numerically analyzed across a spectrum of eccentricity values. Additionally, a microscopic comparative analysis is conducted on the variations in charged species and electric field distributions for different needle cathode cases. Notably, our findings unveil a significant and consistent trend: Trichel pulse magnitude and frequency exhibit a prominent inverse proportionality with the eccentricity of conic cross-sectional needle cathodes. This trend establishes a distinct sequence in Trichel pulse magnitudes and frequencies, with elliptic needles exhibiting the highest values, followed by parabolic and hyperbolic needles. The negative air discharges are mathematically modeled using a hydrodynamic approach and simulated using COMSOL Multiphysics software. This sensitivity analysis emphasizes the important role of electrode geometry on gas discharge plasma behavior, providing critical insights for optimizing plasma-driven technologies and electrical insulation systems.