Theoretical Analyse On The Spatio-temporal Of Discharge In Short-SF₆-gap With Dielectric-covered Electrodes

Electrodes covering short SF₆gap discharge was attentioned since1988when it was first reported because it’s significant advantages and enormousprospects for industrial applications.Meantime, electrode covering short air-gapdischarge is also one of the main devices to generate low temperatureplasma.However, with the electrode covering short air-gap discharge which is astrong non-linear space and extended dissipative discharge system, the dischargebehavior is very complex.So the thesis made a numerical simulation on dischargecharacteristics of electrode covering short air-gap discharge system and the effectof spatial discharge structure on discharge behavior.It not only made people havea better understanding of this discharge system in theory, but also has importantpractical value and theoretical significance on the detection of gas-insulateddischarge system, and plasma generation, stability and control.In order to study the law of electrode covering short air-gap discharge,andunderstand the dynamic behavior of electrode covering short air-gapdischarge,the thesis established a one-dimensional self-consistent hydrodynamicsof gas discharge model based on the SF₆including including electron and ioncontinuity and momentum equations, using the current balance equation insteadof the Poisson equation, numerical simulation of the dynamical behavior of theelectrode coverage under short air gap discharge.The calculated results show thatwhen the air gap in the electric field exceeds the breakdown threshold, thedischarge gas will form the discharge pulse, and its essence is that the motion ofelectric charges form the electron avalanche discharge. At the same time, thethesis gain the spatial and temporal distribution of electron density and iondensity in the process of electrode covering short air-gap discharge.Thesimulation results show that short air gap, the voltage amplitude and driving frequency will not only affect the air-gap discharge voltage pulse amplitude, butalso promote the changes of pulse number.The media surface accumulation ofcharge is the formation of the root causes of the multi-pulse air-gapdischarge.Accumulation of medium surface charge is the root cause of theformation of multi-pulse air-gap discharge.The further simulation showed that the electrode covering short air-gapdischarge system has chaotic characteristics. Therefore, the thesis obtain twodifferent access to chaos by changing the parameters of discharge space.This notonly explained the formation mechanism of the short air-gap discharge from themicro, but also give chaotic phenomena a scientific explanation in power system.