The Research On Vacuum Acquirement And Heat Sink Of Space Environment Simulator

Space environment simulator is used to simulate vacuum,dark and cold,solar radiation of space.Reappear or equal space environment parameters of star or device.That can be used in satellite or hot vacuum and heat balance experiment.At present,it is necessary to test the function of the spacecraft in space environment before launched.And in order to improve reliability of the spacecraft and guarantee the working life of it,the design of heat control system should be checked according to the test results.Therefore,space simulation simulator is very important for space technology.In order to adapt the develpment of space technology,from the 1950s,space simulator is studied in USA,Russia and many company.In 1998,KM6 main simulation chamber(diameter is 12m,hight is 22.4m) is developed in our country,which is one of the world's three manned spacecraft space envionment experimental device and reaches the international advanced level of similar device.But in China, overall space simulator capacity remains inadequate,the performance of the vacuum of the environmental simulation devices need to be improved, heating refrigeration methods are outmoded, alcohol is choosed as refrigerant other negative and many other adverse factors. Therefore, we need a new vacuum acquirement methods and ways to improve temperature control.The study uses dry scroll pumps as coarse pumps(pumping speed is 8 L/s),and use Roots pump dry oil-free prime vacuum unit as booster pumps(pumping speed is 30 L/s).Cryopump is used as main pump(the pumping speed is 5000 L/s)to guarantee the quality of the space environment clean of the vacuum system access.Vacuum setup time can meet the requirement that there is more that 10 minutes to lauch vacuum discharge before the pressure is reduced to 1.3Pa, and with parallel work of low temperature precooling pump and prime vacuum unit,limit vacuum(≤5×10-5Pa)setup time is reduced to less than 3.5 hours. At the same time the radiation barrier settled between cryopump and heat sink guarantees the application of cryopump under thermal radiation condition.This study effectively meet the requirement that the vacuum chamber size of space environment simulator isΦ900 mm×1000mm.And considering the main mode of transmission is thermal radiation when the vacuum degree is higher than 10-2Pa,the radiation barrier materials are choosed to isolate heat sink from stainless steel track in the vacuum chamber, and convection and heat conduction overlooked. Heat sink choose "fish skeleton" structure,and bath liquid converges synchronously from bottom to top through 1413mm semi-circular arc to ensure thermal stability and uniformity of the temperature field. Temperature control system uses integral heating and refrigeration MagNum91 temperature control equipment, and it's heating and refrigeration power is adjustable to meet the rate of cooling and heating. The Experimental results show that the heating rate of heat sink is above 1.2℃/min when the temperature is -60℃to+100℃.Cooling rate is above 1℃/min when the temperature is -35℃to +80℃,and it is above 0.5℃/min when the lower temperature is -50℃to -35℃and the higher temperature is +80℃to +100℃. Stability of heat sink is 0.2℃/h.The effectiveness of the overall design is satisfied.