| Pulsed power technology is usually researched for energy and defense scientific area,such as controllable fusion,high-power microwave,high-power laser,electromagnetic pulse,etc.In order to meet the demands on the degree of output power and the life of multi-run,it's necessary to optimizing the pulsed power equipment.The insulation system is regarded as one of the key components and its dielectric strength decides the degree of current and the operation stability.Practice indicates that surface flashover has been the main factor to limit the dielectric strength of the insulation system in vacuum.The research on vacuum surface flashover of solid insulators in a practical condition is meaningful for evaluating the insulation system and improving the pulsed power equipment.Primary Test Station(PTS)had been completed in CAEP and poly(styrene-co-divinyl benzene)was used as the main insulator in this device.This kind of material is composed by polystyrene long chains cross-linked by divinyl benzene(DVB)molecules.The cross-linking network structure make the material performs excellent inti-flashover property and mechanical strength.The heat initiated free radical bulk polymerization is the main way to synthesis this material.However,the radiation process can avoid the implosion and improve the purity of the product.In this paper,poly(styrene-co-divinyl benzene)was synthesized with benzene and DVB as the monomers via static ?-ray radiation.The cross-linking density was changed by adjusting the radio of raw materials.The relationship between cross-link structure and flashover was studied and discussed.Meanwhile,the cured samples were further irradiated by excess ?-ray and the aging features had been characterized.The influence of materials aging on flashover property was studied and discussed.Furthermore,when PTS device runs,there are lots of soft X-rays released from metal loads and the insulators are exposed in the radiation condition for long time.This paper designed an experience chamber on the PTS device and researched the influence of soft X-ray on flashover property.The main contents of this paper are followed:(1)The poly(styrene-co-divinyl benzene)materials with different cross-linking density were synthesized by styrene,divinyl benzene via “heat-radiation” process.(2)The cross-linking structures were characterized by Fourier transform infrared spectroscopy(FT-IR)and Solid State Nuclear Magnetic Resonance(SSNMR).Dielectric properties,surface potential decay and flashover voltages were tested and discussed.(3)The cured samples are irradiated by excess ?-ray in air and the aging behaviors were characterized by FT-IR and XPS.The dielectric property,surface potential decay and flashover voltages were tested and discussed(4)Radiation chamber was designed and put up on the PTS device.The influences of soft X-ray on samples and characterized by XPS and the flashover voltages were tested and discussed.The main conclusions are given followed:(1)The cross-linking density has a proportional relation with the content of DVB.(2)As the cross-linking density increases,the flashover voltages are improved firstly and then reduced,which is attributed to the permittivity and the capability of electrons capturing.The sample P20 with a DVB content of 2.0 wt.% shows the optimal anti-flashover ability.(3)The surface of sample is oxidized obviously after excess ?-ray irradiation in air.Same polar groups such as C=O and C-O are produced.(4)Flashover voltages are measured to be inversely proportional to the content of oxygen.(5)The flashover voltages are reduced obviously after long-term soft X-ray irradiation and the oxidation of surface is one of the main factors. |
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