简介:Inthisstudy,micro-hollowcathodedischarge(MHCD)isinvestigatedbyafluidmodelwithdrift-diffusionapproximation.TheMHCdeviceisacathode/dielectric/anodesandwichstructurewithoneholeofadiameterD=200μm.ThegasisaNe/Xemixtureatapressurep=50~500Torr.Theevolutionsofthedischargeshowthattherearetwodifferentdischargemodes.AtlargerpDthedischargeplasmaandhighdensityexcitedspeciesexpandalongthecathodesurfaceand,aringeddischargemodeisformed.AtsmallerpD,thedischargeplasmaandtheexcitedspeciesexpandalongtheaxisofthecathodeaperturetoformacolumnardischarge.
简介:Thispaperreviewsthetheoreticalfoundationsofzonalflow,puttingemphasisonthelinearresponsefunctionofplasmatotheexternalflowdrive.Anextensionofthetheoryismadeinordertoapplyittohelicalsystemsandtostudythepropertiesofthezonalflowinthelowfrequencyrange.Furtherrefinementofthetheoryismadeincorporatingtheorbitaleffectsofparticlesmoreprecisely,andtheroleofneoclassicalpolarizationcurrentisidentified.
简介:Thedischargeoperationregimeofpulsemodulatedatmosphericradiofrequency(RF)glowdischargeinheliumisinvestigatedonthedutycycleandfrequencyofmodulationpulses.Thecharacteristicsofradiofrequencydischargeburstintermsofbreakdownvoltage,alpha(α)-gamma(γ)modetransitionvoltageandcurrentaredemonstratedbythedischargecurrentvoltagecharacteristics.TheminimumbreakdownvoltageofRFdischargeburstwasobtainedatthedutycycleof20%andfrequencyof400kHz,respectively.Theα-γmodetransitionofRFdischargeburstoccursathighervoltageandcurrentbyreducingthedutycycleandelevatingthemodulationfrequencybeforetheRFdischargeburstevolvingintotheignitionphase,inwhichtheRFdischargeburstcanoperatestablyintheγmode.ItproposesthattheintensityandstabilityofRFdischargeburstcanbeimprovedbymanipulatingthedutycycleandmodulationfrequencyinpulsemodulatedatmosphericRFglowdischarge.
简介:Moleculardynamics(MD)simulationswereperformedtoinvestigateF+continuouslybombardingSiCsurfaceswithenergiesof100eVatdifferentincidentanglesat300K.Thesimulatedresultsshowthatthesteady-stateuptakeofFatomsincreaseswithincreasingincidentangle.Withthesteady-stateetchingestablished,aSi-C-Freactivelayerisformed.ItisfoundthattheetchingyieldofSiisgreaterthanthatofC.IntheF-containingreactionlayer,theSiFspeciesisdominantwithincidentangleslessthan30o.Forallincidentangles,theCFspeciesisdominantoverCF2andCF3.
简介:InthedischargeofEASTtokamak,itisobservedthat(2,1)neoclassicaltearingmode(NTM)istriggeredbymodecouplingwitha(1,1)internalmode.Usingsingularvaluedecomposition(SVD)methodforsoftX-rayemissionandforelectroncyclotronemission(ECE),thecouplingspatialstructuresandcouplingprocessbetweenthesetwomodesareanalyzedindetail.TheresultsofSVDforECErevealthatthephasedifferencebetweenthesetwomodesequalstozero.Thisisconsistentwiththeperfectcouplingcondition.Finally,performingstatisticalanalysisofγ1/1,ζ1/1andω2/1,wefindthatγ1/1moreaccuratelyrepresentsthecouplingstrengththanζ1/1,andγ1/1isalsostronglyrelatedtothe(2,1)NTMtriggering,whereγ1/1isthewidthof(1,1)internalmode,ζ1/1istheperturbedamplitudeof(1,1)internalmode,andω2/1denotesthemagneticislandwidthof(2,1)NTM.
简介:Inthisresearch,thenonlinearevolutionofjet-likespikesinthesingle-modeablativeRayleigh-Taylorinstability(ARTI)inthepresenceofpreheating,isstudiednumerically.Itisdemonstratedthatthepreheatingplaysanessentialroleintheformationofjet-likespikesinthenonlinearARTI.Theevolutionofjet-likespikesintheARTIwithpreheatingconsistsofthreestageswithdistinctlydifferentdistinguishingfeatures.Intheearlystage,thepreheatingcontributestosignificantlyincreasethedensity-gradientscalelengthandbroadenthevelocityprofileoftheablationsurface,wheretheformercanreducethelineargrowthoftheARTIandmitigatethegrowthofitsharmonics.Inthemiddlestage,theablativeKelvin-Helmholtzinstabilityisdramaticallysuppressedduetotheablationeffects.Inthelatestage,thejet’slength(i.e.bubble-spikeamplitude)isfurtherincreasedbythebubbleaccelerationinthehighlynonlinearARTI,resultingeventuallyintheformationofjet-likespikes.