Download The Role of Photoionization in Negative Corona Discharge H. Y. Sun

The Role of Photoionization in Negative Corona Discharge
H. Y. Sun
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. 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. In weak
ionization region, these photoelectrons can be used as seed electrons to produce secondary
electron emission avalanche (SEEA). Characteristics for positive direct current corona discharges
in air under the action of photoionization has been well developed in recent years, while the role
of photoionization in negative corona has seldom studied so far.
In the presentation, the models of continuity equations coupled with Poisson’s equation and
Helmholtz differential equations are used to explore the effect of photoionization on negative
corona discharge at different voltages in air. The relationships between the magnitude of the first
pulse and applied voltage as well as that between the interval and applied voltage will be shown.
Moreover, the current pulses are also presented under different secondary emission coefficients
and the details of the Trichel pulse are discussed.
Biography
Hongyu Sun was born in Liaoning province, China, in 1993.
He received the B.S degree from the Department of Renewable Energy, North
China Electric Power University, Beijing, China, in 2015.
His major research interests include electromagnetic numerical simulation,
plasma physics, corona and streamer discharge and the optimization of high-voltage insulation in
GIS systems.
A Method for calculating electric double-layer capacitance
Binxian Lu
At present, HVDC technology has been paid more and more attention because of its excellent
characteristics. Its application technology has been well developed. Converter valve is an
important component of HVDC technology, but it will produce a lot of heat when it works. In
practice, deionized water is usually applied as coolant. However, the corrosion and deposition of
the converter valve in cooling water occur frequently. It is confirmed that Faraday current and
double layer current through the electrode are crucial to corrosion and deposition in accordance
with related research.
In this presentation, the models of Transport equation and Poisson’s equation are used to explore
the effect of ion motion in Helmholtz and Gouy-Chapman layer. The models of electric field
coupled with electrode dynamics are used to explore the effect of polarization current at
different hypothetical double layer capacitance. The relationships between the over potential of
the electrode and double layer capacitance as well as that between the over potential and
polarization current will be shown. Moreover, the practical double layer capacitance will be given
via the two models.