Abstract
The characteristics of negative corona discharge in practical applications are strongly dominated by environmental parameters, such as air pressure. An axisymmetric hydrodynamic drift-diffusion model considering the effect of air pressure and photoionization has been established in this study based on a traditional needle-to-plate configuration in dry air at room temperature. Trichel pulses, electron density, negative ion density, and electric field distribution during discharge are discussed to investigate the effect of air pressure and photoionization. The results show that the magnitude of the first Trichel pulse without photoionization decreases from 0.92 to 0.6 mA with the increase in the air pressure (0.7–1.1 atm). However, the magnitude of the third Trichel pulse without photoionization increases from 0.28 to 0.55 mA with the increase in the air pressure (0.7–0.9 atm), while it decreases from 0.55 to 0.47 mA with the increase in the air pressure (0.9–1.1 atm). Moreover, the decrease in the air pressure could result in faster movement of charged particles. The role of photoionization under different air pressures is also discussed by numerical simulations.
Highlights
Under the continuous influence of the applied electric field, the positive ions are drawn into the tip electrode and the negative ions diffuse into the gap space, which lead to the appearance of the pulse corona current
Different air pressures varying from 0.7 to 1.1 atm are assumed in our simulation to investigate the effect of air pressure and scitation.org/journal/adv discharge space that causes this phenomenon
The influence of air pressure (0.7–1.1 atm) and photoionization on negative corona discharge has been studied by an axisymmetric hydrodynamic drift-diffusion model
Summary
As a common low-temperature plasma, the corona discharge refers to the local self-sustained discharge of a gas medium under a non-uniform electric field. In recent years, corona discharge plasma has played a major role in high-tech industries owing to its unique characteristics, such as in fields of biomedicine, water pollution treatment, nanomaterial manufacturing, electrostatic dust removal, material surface modification, and new artificial rainfall. Because the environment in which corona discharge occurs is complex and changeable, the characteristics of corona discharge depend on many factors, including the electrode shape, the distance between electrodes, gas composition, photoionization, air pressure, ambient temperature, humidity, and airflow speed. many studies have been carried out to study the effects of different conditions on corona discharge, due to the complicated actual operating environment and mechanisms of corona discharge, further research on the effects of environmental factors on the corona discharge is needed to deepen the understanding of corona discharge mechanisms, thereby leading to a better guide in the real application of corona discharge. Under the continuous influence of the applied electric field, the positive ions are drawn into the tip electrode and the negative ions diffuse into the gap space, which lead to the appearance of the pulse corona current. The influence of the air pressure on the detailed characteristics of positive corona discharge including pulse magnitude, pulse width, and duration time was studied by Li et al.. Environmental parameters including ambient temperature, air pressure, and humidity were found to have great influence on the negative corona discharge. The specific effects of environmental pressure combined with photoionization on the Trichel pulses, electric fields, electron density, and negative ion density during the process of negative corona discharge are analyzed systematically
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