The Effect Of Charged Particle Irradiation On Structure And Microwave Absorption Properties Of Carbon Film In Concertrated Attenuator

In this paper,the influence of working enviroment of travelling wave tube on carbon film attenuator for navigation and communiation sattellite was studied.60 keV electron and proton irradiation were applied on carbon film in electron accelerator and positive ion accelerator.The variation of attenuator's microwave absorption property and resistance after irradiation was summarized.Meanwhile,we investigated the structure transformation and the relationship between carbon film and microwave absorption property through scanning electron microscopy,profilometer,nanoindentation,Raman spectroscopy and X-ray photoelectron spectropy.It was found that microwave absorption properties did not change much after60keV irradiation.The effect of electron irradiation on the thickness and resistivity of carbon film was not obvious.After 60 keV proton irradiation,the total attenuation of carbon film decreased with the increase of irradiation fluence.The attenuation reached minimum degeree when the irradiation fluence was 1E16 p/cm~2.The thickness and resistivity decreased along with the fluence increasing,which indicated that the thickness reduction is the main cause that affects the microwave absorption property of cabon film.The Raman spectroscopy and XPS analysis proved that electron and proton irradiation can break the C-O bond in the carbon film and reduce the oxygen content inside carbon film.the oxygen would diffuse to the surface.The carbon film on the surface was oxidized due to the irradiation and oxygen diffusing.60 keV electron irradiation did not affect the crystal structure of carbon film,while 60 keV proton irradiation would break the crystal structure of caron film.when the irradiation fluence reached 1E16 p/cm~2,the carbon film would change from nanocrystalline graphite to amorphous carbon.The degreee of crystallization increased and some hydrgen combined with carbon.The thickness of carbon film decreased due to the combination.Meanwhile,it increased the carrier mobility and reduced the electrical resistivity of carbon film.