Study On The Characteristics Of Spark Discharge

In the process of production and processing,fire and explosion accidents caused by electric spark occur frequently.A full understanding about law and characteristics of electric spark discharge can provide clear guidance for technology of prevention and control of ignition sources and explosions.Process of spark discharge is a dynamic energy release process,which is affected by many factors,including energy and electrode characteristics.In order to explore the influence of energy(voltage,capacitance)and electrode parameters(electrode gap,electrode shape,electrode material)on the characteristics of spark discharge,a spark discharge generating device is set up.The variation of voltage and current with time is obtained under different conditions.The spark discharge power and energy are evaluated by the integral calculation of spark energy.The current waveforms were fitted by using the exponential attenuation sine formula and the influence of spark resistance and inductance on spark discharge is analyzed.At the same time,the influence of different electrode parameters on the breakdown characteristics of spark is revealed by the Comsol simulation of electric field distribution of electrode.The main conclusions are as follows:The influence of energy on the characteristics of electrostatic spark discharge.By adjusting the voltage(U)or capacitance(C)to change stored energy(CU~2/2)of capacitance,the influence of that on the discharge characteristics of electric spark is compared.The results show that the time of discharge increases,spark energy release efficiency and spark resistance decrease and voltage remains stable with the increase of capacitance store energy.The discharge frequency of electric spark waveform increases with the increase of capacitance,but the voltage has no effect on it.The inductance of discharge circuit fluctuates in a certain range with the change of capacitance.The charging voltage has no effect on the inductance of discharge circuit.When the stored energy is equal,the research results under different capacitance show that the spark current at 60nF is less than 30nF and the discharge time,waveform oscillation period,spark energy release efficiency and spark resistance are more than 30nF.According to the calculation formula of capacitor energy storage(CU~2/2),when energy storage is equal,the charging voltage of 60nF is less than 30nF.It could be concluded that the discharge efficiency of spark of large capacitance(small voltage)is greater than that of small capacitance(large voltage)under the condition of breakdown within the experimental energy range.Effect of electrode parameters on electrostatic discharge characteristics.Under different electrode gaps,the peak field strength decreases with the increase of the electrode gap under the same voltage,so the breakdown voltage increases with the increase of the electrode gap.The peak of spark current decreases with the increase of electrode gap after breakdown.Release efficiency of spark energy and spark resistance increases with the increase of electrode gap.The position of the peak field strength of the blunt body electrode is different from that of other shaped electrodes,which means the breakdown position is different.The peak field strength of tip angle 30~o,tip angle 90~o and spherical electrode is at the tip,while the peak field strength of the blunt body is at the chamfer of both ends.The peak value of the field strength from large to small is tip angle 30~o,tip angle 90~o,bluff body,spherical electrode.Therefore,the breakdown voltage required by spherical electrode is higher in the same case.Copper and tungsten electrode materials have no effect on the field intensity distribution.The energy loss of tungsten electrode is greater than that of copper electrode at low energy.