Abstract
A corona discharge measurement system and simulation model are presented to investigate the effects of photoionization and ion-impact secondary emission process in negative corona discharge. The simulation results obtained is shown good agreement with experimental observations. Distribution of electron density along the symmetry axis at three critical moments is shown and the role of photoionization in negative corona discharge is clearly explained. Moreover, the current pulses are also presented under different secondary emission coefficients and the effect of the secondary emission coefficient is discussed.
Highlights
Negative ions and electrons will coexist at the head of the avalanche in negative corona discharge and a portion of photoelectrons emitted by the collisions will be absorbed by molecules as negative ions
The room temperature is 24.4◦C at atmospheric pressure, and the corona onset voltage is equal to -5.0 kV under the conditions above in the experiment
A voltage of -5.5kV was applied to the needle electrode from a negative high voltage direct current (HVDC) voltage source
Summary
When onset voltage is applied to a needle electrode of a point-plane setup, the corona will sustain without the existence of the external ionization source.[1,2,3] Positive, negative ions and electrons will coexist at the head of the avalanche in negative corona discharge and a portion of photoelectrons emitted by the collisions will be absorbed by molecules as negative ions. Model was built by assuming that the photoionization term in the equations has similar properties with uniform background ionization.[18] Classical integral methods were utilized to calculate the photoionization source term and an improved Eddington approximation is shown to be very accurate to calculate the photoionization term.[19,20,21,22] it is inevitable that these approaches are time consuming. The results of the developed model were validated by direct comparisons of the classic integral model at atmospheric pressure.[23] This manuscript presents a model of continuity equations coupled with Poisson’s equation and Helmholtz differential equations to explore the effect of photoionization in negative corona discharge at atmospheric pressure. A series of Trichel pulses for different secondary emission coefficient is successfully shown
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