Polytetrafluoroethylene (Teflon), a widely used spacecraft material, isstudied to investigate the vacuum ultraviolet (VUV) effects and its synergistic effects with atomicoxygen (AO) in a ground-based simulation facili...Polytetrafluoroethylene (Teflon), a widely used spacecraft material, isstudied to investigate the vacuum ultraviolet (VUV) effects and its synergistic effects with atomicoxygen (AO) in a ground-based simulation facility. The samples before and after the experiments arecompared in appearance, mass, optical properties and surface composition. The reactioncharacteristics of Teflon are summarized and the reaction mechanisms are analyzed. The followingconclusion can be drawn: at the action of VUV the Teflon sample surface is darkened for theaccumulation of carbon; and when the sample is exposed to AO, the carbon is oxidized and thedarkening surface is bleached; the synergistic effects of VUV and AO may cause the erosion of Teflonmore severe.展开更多
Vacuum ultraviolet radiation of Upilex-S polyimide film 25 μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on t...Vacuum ultraviolet radiation of Upilex-S polyimide film 25 μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on the films were observed and the nanoparticles formed on the surface consist mainly of carbon clusters.Changes in the composition and the chemical characteristics of film surface after radiation were identified by X-ray photoelectron spectroscopy(XPS).Relative O content in the radiated area was found to be higher,while N content was lower than in the pristine area.This indicates that Upilex-S polyimide film releases N atoms as volatile species.And the C1s,O1s envelopes were fitted using Multipak Spectrum software.The surface morphologies on iradiated area were examined by Atomic Force Microscope(AFM).Pieces of radiant products protrude from the eradiated surface,leading to considerable roughness for the iradiated area.And the surface transmittance of Upilex-S film after radiation reduces.展开更多
Polysiloxane/SiO2 hybrid coatings have been prepared on Kapton films by a sol-gel process. The erosion resistance of polysiloxane/Si02 （20 wt pct） coating was evaluated by exposure tests of vacuum ultraviolet radiat...Polysiloxane/SiO2 hybrid coatings have been prepared on Kapton films by a sol-gel process. The erosion resistance of polysiloxane/Si02 （20 wt pct） coating was evaluated by exposure tests of vacuum ultraviolet radiation （VUV） and atomic oxygen beam （AO） in a ground-based simulation facility. The experimental results indicate that this coating exhibits better AO resistance than pure polysiloxane coating. The erosion yield （Ey） of the polysiloxane/Si02 （20 wt pct） hybrid coating is about 10-27 cm3/atom, being one or two orders of magnitude lower than that of polysiloxane. VUV radiation can affect the erosion process greatly. Under simultaneous AO and VUV exposure, the value of Ey of the polysiloxane/5iO2 （20 wt pct） hybrid coating increases by 3g% compared with that under single AO exposure.展开更多
A new type of AC PDP(alternating current plasma display panel) cell with a five-electrode structure is developed to improve the luminous efficiency of AC PDP.The discharge efficiency of this new cell structure is inve...A new type of AC PDP(alternating current plasma display panel) cell with a five-electrode structure is developed to improve the luminous efficiency of AC PDP.The discharge efficiency of this new cell structure is investigated by a 2D fluid simulation. Continuity equations and flux density equations for charged particles and excited atoms, energy balance equation for electrons are included in the model. The discharge gas is He+5%Xe. The reactions of ionization, excitation, recombination, and radiation are taken into account. The vacuum ultraviolet radiation efficiency of the five-electrode cell structure is about 20% higher than that of a conventional three-electrode cell structure.展开更多
文摘Polytetrafluoroethylene (Teflon), a widely used spacecraft material, isstudied to investigate the vacuum ultraviolet (VUV) effects and its synergistic effects with atomicoxygen (AO) in a ground-based simulation facility. The samples before and after the experiments arecompared in appearance, mass, optical properties and surface composition. The reactioncharacteristics of Teflon are summarized and the reaction mechanisms are analyzed. The followingconclusion can be drawn: at the action of VUV the Teflon sample surface is darkened for theaccumulation of carbon; and when the sample is exposed to AO, the carbon is oxidized and thedarkening surface is bleached; the synergistic effects of VUV and AO may cause the erosion of Teflonmore severe.
基金This work is financially supported by Development Program for Outstanding Young Teachers in Harbin Institute of Technology(No HIT2006 32)
文摘Vacuum ultraviolet radiation of Upilex-S polyimide film 25 μm thick was performed using a gas jet type of vacuum ultraviolet simulator which gives unfixed wavelength from 5 nm to 200 nm.Nanoparticles redeposited on the films were observed and the nanoparticles formed on the surface consist mainly of carbon clusters.Changes in the composition and the chemical characteristics of film surface after radiation were identified by X-ray photoelectron spectroscopy(XPS).Relative O content in the radiated area was found to be higher,while N content was lower than in the pristine area.This indicates that Upilex-S polyimide film releases N atoms as volatile species.And the C1s,O1s envelopes were fitted using Multipak Spectrum software.The surface morphologies on iradiated area were examined by Atomic Force Microscope(AFM).Pieces of radiant products protrude from the eradiated surface,leading to considerable roughness for the iradiated area.And the surface transmittance of Upilex-S film after radiation reduces.
文摘Polysiloxane/SiO2 hybrid coatings have been prepared on Kapton films by a sol-gel process. The erosion resistance of polysiloxane/Si02 （20 wt pct） coating was evaluated by exposure tests of vacuum ultraviolet radiation （VUV） and atomic oxygen beam （AO） in a ground-based simulation facility. The experimental results indicate that this coating exhibits better AO resistance than pure polysiloxane coating. The erosion yield （Ey） of the polysiloxane/Si02 （20 wt pct） hybrid coating is about 10-27 cm3/atom, being one or two orders of magnitude lower than that of polysiloxane. VUV radiation can affect the erosion process greatly. Under simultaneous AO and VUV exposure, the value of Ey of the polysiloxane/5iO2 （20 wt pct） hybrid coating increases by 3g% compared with that under single AO exposure.
基金The project supported by 2002 project for Science and Technology of Ministry of Education
文摘A new type of AC PDP(alternating current plasma display panel) cell with a five-electrode structure is developed to improve the luminous efficiency of AC PDP.The discharge efficiency of this new cell structure is investigated by a 2D fluid simulation. Continuity equations and flux density equations for charged particles and excited atoms, energy balance equation for electrons are included in the model. The discharge gas is He+5%Xe. The reactions of ionization, excitation, recombination, and radiation are taken into account. The vacuum ultraviolet radiation efficiency of the five-electrode cell structure is about 20% higher than that of a conventional three-electrode cell structure.
