低温等离子体表面处理技术

低温等离子体表面处理技术PlasmaandfirstwallIntroductionTodayIwilltalkaboutsomethingaboutmystudyonthefirstwallinthetokamak.Firstly,Iwillshowyouthatwhattheplasmaisinourlifethoughtthefollowingpicturessuchas:Fig.1LighningFig.2AuroraFig.3AstrospaceJustasthepicturesmentionedabove,theyareallconsistofplasma.But,whatdoeshaveintheplasma,nowourscientisthadgivenadefinitionthattheplasmastateisoftenreferredtoasthefourthstateofmatterandcontainsenoughfreechargedparticles（negativeions、positiveions）andelectronics.Likethephotobelow.Fig.4PlasmaproductionPlasmaproductionInourresearch,weproducetheplasmathroughanICP(inductivelycoupledplasma)deviceasfollow：ThroughtheRF(radiofrequency)source、powergeneratorandmatchingbox,wewillgettheplasmaweneedintheexperiment.TheFig.6showsustheplasmaproducedbytheRFsource.Fig.6TheICPplasmaPlasmadiagnosisAndthenweneedtodiagnosetheplasmacharacteristicsthroughsomemethodslikespectrumandprobe.Fig.7TheplaneprobeWeusedtheplaneprobetodetectionthetemperatureofelectronicsandthedensityoftheplasmaastheFig.8andFig.9.Fig.8electronictemperatureWecanseeamongthepowerof3000w-8000w,thechangeofelectronictemperatureisnotsharp.Andatthepressureof0.258Pa,theelectronictemperatureisgoingupobviously.Fig.9PlasmadensityIntheFig.9,wecanconfirmthatastherisingofthepower,theparticledensityisalsomoreandmorehigh.Andbeforethepressureof0.42Pa,theparticlesdensityisrisingastheincreaseofthepressure.Buttheparticlesdensityisdroppedafterthepressureof0.42Pa.AndthanweusedthespectrographtodetectiontheparticlesofhydrogenastheFig.11shownus.Fig.10ThePIspectrographFig.11ThehydrogenspectrumWefindthatastheincreasingofthepower,therearefourcurvesoccurred.Butwhenthepowerreachstoabout2000wand4000w,theHH、haveacapacity.Whenwehaveaclearknowaboutthecharacteristicsoftheplasma.WeusetheplasmatodealwiththefirstwallmaterialssuchasW(tungsten).PlasmainteractionwiththefistwallInourexperiments,weputtheWintheplasma,andacceleratetheHe+particlesorH+usingastaticelectricfieldsothattheycanownapowerfulenergytointeractionwiththematerials.Intheexperiments,wechoicethedifferentpowerfulparticlestodealwiththeW.Andaftertheexperiment,weusedSEMtoanalyzethesurfaceofthematerials.ThesurfaceoftheWcanbeclearlyobservedthathavegrownsomenanostructurethroughtheSEMliketheFig.12.Fig.12SEMimagesofsamplesexposedtoameanionicfluxof1.28E22ion/m2/swithheliumfluencewas1.0E26m-2andanionincidentenergywas（A）10eV、（B）20eV、（C）50eV、（D）100eV、（E）400eV、（F）600eV.Fig.13Cross-sectionalSEMmicrographofthesamplesshowninFig.12,respectivelyTheFig.13showusthecross-sectionalSEMmicrographofthesamples,wecanseethattherearemanynanostructureformedonthesurfaceoftheW.Andthenanostructurecangrowupastheparticlesownhigherenergy.1um（A）(B)（C）（D）（E）（F）（e）（f）（a）（b）（c）（d）Fig.14Cross-sectionalSEMmicrographofCircularRegion,shownintheFig.13（f）Butinourexperiments,wefindadifferentphenomenonwhentheparticleshaveapowerfulenergyabout600eV,therearemanyswellonthesurfaceoftheW.Andthroughthecross-sectionalwecanseetheyarehollowintheswell.ConclusionInourresearch,wehavemainthreestepsasfollow:Firstly,webuildadevicetoproducetheplasmaweneed.Secondly,wediagnosedthecharacteristicsoftheplasmasuchaselectronicstemperatureandplasmadensity.Finally,weusedtheplasmatodealwiththefirstwallmaterialslikeW,andanalyzedthesurfaceoftheWtojudgewhethertheWisfitforthefirstwallmaterialsornot.