Research On Discharge Behavior Of Typical Gases At Low Pressure

Outgassing from material in spacecraft is a common phenomenon when the spacecraft is on the orbit,which causes the gas pressure near the material to rise to a low pressure of 10-3 to 103 Pa.At the same time,the near spacecraft's pressure range in the near space is also in the low pressure range.This paper studies the low-pressure discharge behavior of different gas components(methane,nitrogen,helium,air,methane-nitrogen mixed gas,methane and helium mixed gas)and the low pressure of dielectric materials(polytetrafluoroethylene and epoxy glass fiberboard).Flashover behavior along the surface.By changing the pressure of the environment,the variation law and characteristics of the breakdown voltage and flashover voltage with the ambient pressure are studied.Under the same pressure conditions,the electrode spacing is changed,and the evolution rule and characteristics of the discharge threshold with the electrode state under different electrode states are studied.The discharge experiments were carried out separately for the environment of a single gas(methane,nitrogen,and helium)and mixed gas(mixture of air,methane and nitrogen,and methane and helium).The variation of the discharge threshold with the electrode spacing and the gas pressure was studied by using either the variable gas pressure or the electrode spacing.The experimental results show that the gas pressure is the main factor affecting the discharge mode.Arc discharge is the main factor when the gas pressure is high,and glow discharge is the main one when the gas pressure is low.The influencing factors of the discharge threshold of mixed gas and nitrogen gas are the same and are affected by the electrode spacing and gas pressure.Under the same conditions,the air discharge threshold is higher than that of nitrogen.The methane and nitrogen mixed gas or methane and helium mixed gas discharge threshold is not lower than that of a single gas,indicating that the mixed gas has its unique discharge characteristics.Surface flashover is a kind of discharge phenomenon that occurs on the surface of dielectric material.This paper takes the insulating material PTFE used in spacecraft and epoxy glass board commonly used in PCB as the research object,and explores the gas pressure and the distance between electrodes to flashover.The effect of voltage.The experimental results show that the gas pressure has a significant effect on the variation of flashover voltage between PTFE and epoxy glass fiberboards.The flashover voltages of different pressure ranges are different.The flashover voltage sensitive interval of the above two materials is between 0.1~1 Pa.The increase in air pressure drops rapidly.Above 1 Pa,the flashover voltage threshold is 1000 V(polytetrafluoroethylene)and 600 V(epoxy fiberglass board),while the flashover voltage is less than 0.1 Pa and the flash voltage is as high as 40 k V.(Polytetrafluoroethylene)and 28 k V(epoxy glass fiberboard),indicating that there is a risk of flashover discharge above 0.1 Pa at low pressure.By comparing the discharge threshold values of air under different pressures,the risk interval of air discharge was determined and corresponded to the height of the airspace,indicating that within the range of 48 km to 65 km from the adjacent space,the risk of low pressure discharge is easily generated when the aircraft is in service.For onorbit service satellites,the phenomenon of gas evolution is significant at local or organic material concentration sites,and there is a higher risk of low-pressure gas discharge and the risk of flashover discharge.