简介:TheDCreactorisanimportantpieceofequipmentforrestrainingloopandripplecurrentsintheinternationalthermonuclearexperimentalreactor(ITER)converterpowersupplysystem.Asthereactorisoperatedatasteadystateof27.5kAandneedstowithstandapeakcurrentof175kA,sothedesignoftheDCreactorusedintheITERconverterpowersupplysystemisnecessary.Anewwater-coolingdry-typeair-corereactorisdesignedinthiswork.Thedetailedstructuralparametersarecalculatedbytheoreticalformulas,andthenthestructureisoptimizedbyelectromagneticsimulationwithANSYS.Finally,thermalanddynamicstabilityanalysesareperformedtoverifythetemperatureandstressataratedcurrentof27.5kAandpulsedcurrentof175kA.TheanalysisresultsshowthatthetemperatureandstressmeettherequirementsoftheITERconverterpowersupplysystem.
简介:AwaterplasmawasgeneratedbyDCarcdischargewithahafniumembeddedrodtypecathodeandanozzle-typeanode.Thedischargecharacteristicswereexaminedbychangingtheoperationparameterofthearccurrent.Thedynamicbehaviorofthearcdischargeledtosignificantfluctuationsinthearcvoltageanditsfrequency.Analysesofthehighspeedimageandthearcvoltagewaveformshowedthatthearcdischargewasintherestrikemodeanditsfrequencyvariedwithinseveraltensofkilohertzaccordingtotheoperatingconditions.Thelargerthermalplasmavolumewasgeneratedbythehigherflowfromtheformingsteamwithahigherrestrikefrequencyinthehigherarccurrentconditions.Inaddition,thecharacteristicsofthewaterplasmajetwereinvestigatedbymeansofopticalemissionspectroscopytoidentifytheabundantradicalsrequiredinanefficientwastetreatmentprocess.
简介:Acomparativestudyoftheneedle-to-liquidplasmainthecontinuousmodewithDCandACexcitationsisdetailedinthispaper.Allplasmasstudiedhereareshowntobeglowdischarges.Thisstudyisbasedonmeasurementsofseveralkeyparameters,includingelectricalenergy,opticalemissionintensitiesofactivespecies,rotationalandvibrationaltemperatures,andtemperaturesoftheneedleandliquidelectrodes.ACplasmascanproduce1.2~5timeshigherexcitedstateactivespeciesthanDCplasmasunderthesamedissipatedpower.ACexcitedliquidplasmashavethehighestenergyutilizationefficiencyamongthethreesystems(ACexcitedplasmas,DCexcitedplasmaswithwateranodeandDCexcitedplasmaswithwatercathode);mostoftheenergyisusedtoproduceusefulspeciesratherthantoheattheelectrodesandplasmas.
简介:AdesignofthemainAC/DCconvertersystemforITERisdescribedandthecon-figurationofthemainAC/DCconvertersispresented.Toreducethereactivepowerabsorbedfromtheconverterunits,themainAC/DCconvertersaredesignedtobeseries-connectedandworkinasequentialmode.Thestructureoftheregulatoroftheconvertersystemisdescribed.AsimulationmodelwasbuiltupforthePSCAD/EMTDCcode,andthedesignwasvalidatedaccordingly.Harmonicanalysisandreactivepowercalculationoftheconvertersunitsarepresented.Theresultsrevealtheadvantageofsequentialcontrolinreducingreactivepowerandharmonics.
简介:Atypeofelectricaldischargecalledslidingdischargewasdevelopedtogenerateplasmaaerodynamicactuationforflowcontrol.Athree-electrodeplasmasheetactuatordrivenbyrepetitivenanosecondpulseswithanegativeDCcomponentwasusedtogenerateslidingdischarge,whichcanbecallednanosecond-pulseslidingdischarge.Thephenomenologyandbehaviouroftheplasmasheetactuatorwereinvestigatedexperimentally.Dischargemorphologyshowsthattheformationofnanosecond-pulseslidingdischargeisdependentonthepeakvalueoftherepetitivenanosecondpulsesandnegativeDCcomponentappliedontheplasmasheetactuator.Comparedtodielectricbarrierdischarge(DBD),theextensionofplasmainnanosecond-pulseslidingdischargeisquasi-diffusive,stable,longerandmoreintensive.TestresultsofparticleimagevelocimetrydemonstratethatthenegativeDCcomponentappliedtoathirdelectrodecouldsignificantlymodifythetopologyoftheflowinducedbynanosecond-pulseDBD.Bodyforceinducedbythenanosecond-pulseslidingdischargecanbeapproximatelyintheorderofmN.BoththemaximumvelocityandthebodyforceinducedbyslidingdischargeincreasesignificantlyascomparedtosingleDBD.Therefore,nanosecond-pulseslidingdischargeisapreferableplasmaaerodynamicactuationgenerationmode,whichisverypromisinginthefieldofaerodynamics.
简介:Inthiswork,wesimulatenumericallythethermaleffectsinnitrogenatatmosphericpressurecausedbyanegativecoronaDCdischargeoflowcurrent.Amathematicalfunctionthatsimulatestheinjectionofthethermaltransferingasisproposed.Thesimulateddischargeisofanegativepointtoplanemasstype,withaninterelectrodedistanceof12mmandasymmetryabouttheaxisofdischarge.Thespatialandtemporalevolutionofneutralsisanalyzedbasedupontheequationsofcontinuity,momentumandenergyinacylindricalgeometry.Forthegeometryofthesystem,theFCT(fluxcorrectedtransport)procedurewasadopted.
简介:Dependenceofthecurrent-voltagecharacteristicsofanon-transferredDCcascadedplasmatorchusedfornanoparticlesynthesis,ontheplasmacurrentandtheplasmaargongasflowratearereportedinthispaper.Thepotentialstructureinsidethetorchanditsdependenceontheplasmacurrentandgasflowratearealsoinvestigated.Thearcvoltageisseentoexhibitnegativecharacteristicforacurrentbelow150Aandpositivecharacteristicabovethatcurrentvalue.Thevoltagedropneartheelectrodesisfoundtodecreasewiththeincreaseinplasmacurrent.25%ofthetotalvoltageisdroppednearthecathodeataplasmacurrentof50Aandaargonplasmagasflowrateof10literperminute(LPM),anditdecreasesto12%withthecurrentincreasingto300A,andto17%withagasflowrateof25LPM.Thevariationinthetorchefficiencywiththegasflowrateandplasmacurrentisalsoreported.Theefficiencyofthetorchisfoundtobebetween36%and48%.Inaddition,theplasmagastemperatureatvariouspositionsofthereactorandfordifferentcurrentsandvoltagesaremeasuredbycalorimetricestimationwithaheatbalancetechnique.
简介:Inresponsetothecurrentimbalancephenomenonanditsharmfulness,acurrentsharingcircuitmodelisbuiltup,whichrevealstheunderlyingcausesforthecurrentimbalancethroughaquantitativeanalysis.Then,afeasibleapproachofimprovement,namelyenlargementofthelengthofconnectionbusbars,isproposed.Aftertheamendment,itcanbeseenthatthecurrentsharingcoefficientisalmostunityunderratedorfaultcurrentconditions.
简介:Flyashfromamunicipalsolidwasteincinerator(MSWI)withoutpreprocessing(originalflyash,OFA)wasmeltedbyadirectcurrent(DC)plasmaarcfurnacetoinvestigatehowthefeedformsgovernedtheresults.Dioxinsinfluegasfromstackandbag-filterash(BFA)weredetected.ThedistributionofheavymetalsofPb,Cd,As,andCralongthefluegasprocesssystemwasanalyzed.Throughacomparisonoftheresultsfordioxinsandheavymetalsinthisstudyandpreviouswork,carrying-overofflyashparticleswiththefluegasstreamcanbededuced.BasedonthemagneticinductionequationandNavier-Stokesequations,amagnetohydrodynamic(MHD)modelfortheplasmaarcwasdevelopedtodescribetheparticle-carryingeffect.Theresultsindicatethat,a.whenmelted,thefeedformsofMSWIflyashaffecttheresultssignificantly;b.itisnotpreferabletomeltMSWIflyashdirectly,andeffortsshouldbemadetolimitthemasstransferofOFAfromtheplasmafurnace.
简介:Wedevelopedaone-dimensionalhybridmodeltosimulatetheDC/RFcombineddrivencapacitivelycoupledplasmaforargondischarges.ThenumericalresultsareusedtoanalyzetheinfluenceoftheDCsourceontheplasmadensitydistribution,ionenergydistributions(IEDs)andionangledistributions(IADs)onboththeRFandDCelectrodes.TheincreaseinDCvoltagedrivesmorehigh-energyionstotheelectrodeappliedtotheDCsource,whichmakestheIEDsattheDCelectrodeshifttowardshigherenergy,andthepeaksintheIADsshifttowardssmallangleregions.Atthesametime,italsodecreasestheionenergyattheRFelectrodeandenlargestheincidentanglesoftheions,whichstriketheRFelectrode.
简介:Thispaperproposesanewmethodtopredictthecoronaonsetvoltageforarodplaneairgap,basedonthesupportvectormachine(SVM).BecausetheSVMisnotlimitedbythesize,dimensionandnonlinearityofthesamples,thismethodcanrealizeaccuratepredictionwithfewtrainingdata.Onlyelectricfieldfeaturesarechosenastheinput;nogeometricparameterisincluded.Therefore,theexperimentdataofonekindofelectrodecanbeusedtopredictthecoronaonsetvoltagesofotherelectrodeswithdifferentsizes.Withtheexperimentaldataobtainedbyozonedetectiontechnology,andexperimentaldataprovidedbythereference,theefficiencyoftheproposedmethodisvalidated.Accuratepredictedresultswithanaveragerelativelessthan3%areobtainedwithonly6experimentaldata.
简介:Athreedimensionalsteady-statemagnetohydrodynamicmodelisdevelopedforthearcplasmainaDCsubmergedelectricarcfurnacefortheproductionoffusedMgO.Thearcisgeneratedinasmallsemi-enclosedspaceformedbythegraphiteelectrode,themoltenbathandunmeltedrawmaterials.Themodelisfirstusedtosolveasimilarprobleminasteelmakingfurnace,andthecalculatedresultsarefoundtobeingoodagreementwiththepublishedmeasurements.ThebehaviorofarcswithdifferentarclengthsisalsostudiedinthefurnaceforMgOproduction.Fromthedistributionofthearcpressureonthebathsurfaceitisshownthatthearcplasmaimpingementislargeenoughtocauseacrater-likedepressiononthesurfaceoftheMgObath.Thecirculationofthehightemperatureairundertheelectrodemayenhancethearcefficiency,especiallyforashorterarc.
简介:AsinteredTi_(13)Cu_(87)targetwassputteredbyreactivedirectcurrent(DC)magnetronsputteringwithagasmixtureofargon/nitrogenfordifferentsputteringpowers.Titanium-copper-nitrogenthinfilmsweredepositedonSi(111),glassslideandpotassiumbromide(KBr)substrates.Phaseanalysisandstructuralpropertiesoftitanium-copper-nitrogenthinfilmswerestudiedbyX-raydiffraction(XRD).ThechemicalbondingwascharacterizedbyFouriertransforminfrared(FTIR)spectroscopy.TheresultsfromXRDshowthattheobservedphasesarenano-crystallitecubicantirheniumoxide(antiReO_3)structuresoftitaniumdopedCu_3N(Ti:Cu_3N)andnanocrystallitefacecenteredcubic(fcc)structuresofcopper.ScanningelectronmicroscopyandenergydispersiveX-rayspectroscopy(SEM/EDX)wereusedtodeterminethefilmmorphologyandatomictitanium/copperratio,respectively.Thefilmspossesscontinuousandagglomeratedstructurewithanatomictitanium/copperratio(~0.07)belowthatoftheoriginaltarget(~0.15).Thetransmittancespectraofthecompositefilmsweremeasuredintherangeof360nmto1100nm.Filmthickness,refractiveindexandextinctioncoefficientwereextractedfromthemeasuredtransmittanceusingareverseengineeringmethod.Inthevisiblerange,thehigherabsorptioncoefficientofthefilmspreparedatlowersputteringpowerindicatesmorenitrificationincomparisontothosepreparedathighersputteringpower.ThisisconsistentwiththeformationoflargerTi:Cu_3Ncrystallitesatlowersputteringpower.Thedepositionratevs.sputteringpowershowsanabrupttransitionfrommetallicmodetopoisonedmode.Acomplicatedbehaviorofthefilms'resistivityuponsputteringpowerisshown.