Internal Charging And Discharging Characteristics Of Spacecraft Dielectric Materials In Space Environment

Internal charging and discharging effect is one of the key factors causing satellite anomalies in space environment,thus,it is important for safe and reliable operation to master the charge and discharge pattern of dielectric materials.GEO and MEO are two tracks with higher internal charging and discharging risk.Because of the particularity of GEO,charging characteristics of the dielectric materials in this orbit are studied deeply.For MEO,the charging environment vary drastically due to satellites running in and out of the radiation belt.As a result of the high risk of discharging and less relevant literature,it is necessary to study the charging laws of this orbit.In addition,vacuity changes in some enclosed areas or materials surface owing to debris percussion,engine exhaust or other effects can also have a significant impact on voltage.Taking satellites in MEO as an example,this paper analyzes the worst-cast environment of MEO and typical dielectric materials' charging characteristics by FLUMIC model,and then verify above conclusions through the ground simulation test.It can be concluded that the charging potential varies with the orbital period.For materials with smaller time constant,charging potential shows obvious fluctuations in the whole orbital period and achieve high value just when satellite running in radiation belt.For materials with lager time constant,the charging potential fluctuates moderately and keep a high value because of charge long-term accumulation,under this circumstances,the charge effect is the same as that in a sustained irradiation area,and just the time of reaching the maximum potential is later.Another experiment is carried out to study the charging and discharging characteristics in different vacuity.The results show that the maximum potential in same time become higher and grow in number of discharge frequencies with increases in vacuity.When there is a sharply changes in local vacuity of the sample,the materials will have discharging risk.However,when the gas-flow rate is small and jet time is longer,the sample's potential decreases and doesn't appear discharging.