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25 April 2017, Volume 37 Issue 2 Previous Issue    Next Issue

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Surfacecharginganalysisinducedbyelectronbeamimpactdielectric WANG Dan, HE Yong-Ning, LI Yun 2017, 37 (2):  1-10.  doi: 10.16708/j.cnki.1000-758X.2017.0031 Abstract ( 676 )   PDF (2899KB) ( 950 )   Save Forexistingmultipactoroccurredindielectricmicrowavecomponents,moreattentionispaidtomultipactorsourceandsuppressionfromtheaspectofresonanceandemittedelectronyield,whilethestudyaboutinfluenceofsurfacepotentialonmultipactorisrarelyreported.Secondaryelectronemissioncharacteristicswereanalyzed.Finalsurfacepotentialandelectronimpactenergywereemphaticallystudiedwhenelectronbeamwithconstantenergysostenutoimpactedthedielectricsurfacewithvariousinitialsurfacepotential.Surfacepotentialandelectronimpactenergywerecalculatedwhenthesystembecamestable.Calculateddataindicatesthatsteadystateofthesystemisremarkablyinfluencedbyprimaryenergyandthesecondcriticalenergy.Theinfluenceofsurfacepotentialonsecondaryelectronemissionwassystematicallystudiedwhenelectronswithsingleandcontinuousenergyimpactedthedielectricsurface.An-eφenergyshiftingofcriticalenergyisrevealedwhensurfacepotentialisφ.Forelectronbeamwithcontinuousincidentenergy,impactenergyrangeisdramaticllyeffectedbysurfacepotentialofthedielectric,andtheriskofmultipactorisfurtherinfluenced. Related Articles | Metrics

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Preliminarystudiesofelectronbeambombardmentinstrongelectromagneticfieldbreakdown Wu-Cheng, SUN Jun, CHEN Chang-Hua, HUO Shao-Fei, ZHANG Yu-Chuan, CAO Yi-Bing, XIE Jia-Ling 2017, 37 (2):  11-16.  doi: 10.16708/j.cnki.1000-758X.2017.0027 Abstract ( 610 )   PDF (3831KB) ( 444 )   Save Presently， structureoptimizationandtechnologicaltreatmentaretwomainwaystodepressthestrongelectromagn eticfieldbreakdown.Theenergydepositionabout1MeVelectronsinmetalmaterialswasinvestigatedby BetheenergylosslawandMonteCarlosimulation.Theresultsindicatethattheelectronsinthe materialofsmalleratomicnumberanddensityhavemuchlongereffectiverangeandlowerenergydepo sitiondensity.Thereby， thematerialismoreresistanttoelectronsbombardmentandthebreakdownriskcanbeeffectivelyre duced.Withthesameincidentelectronenergy，thecopper， stainlesssteelandtitaniumwereexperimentallycompared.Owingtoitshighdensity， thecopperisdestroyedmosteasily.Simultaneously，thetitaniumshowsgoodperformanceforitslow density.Thefurtherhighpowermicrowave（HPM）experimentsshowthat，with~2.8GWoutput， theoutputmicrowavepulsewidthoftheRBWOcanbeincreasedto27nsfrom18nswhenthestain lesssteelissubstitutedbythetitaniumandthepulseshorteningiseffectivelydepressed. Related Articles | Metrics

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Analyticalmodelforsecondaryelectronyieldofmetals HE Jun, LI Jun, CAO Meng, CUI Wan-Zhao, LIU Chun-Liang 2017, 37 (2):  12-23.  doi: 10.16708/j.cnki.1000-758X.2017.0023 Abstract ( 819 )   PDF (1352KB) ( 714 )   Save Anaccuratemodelforsecondaryelectronyield（SEY）isofgreatimportanceforthecalculationofmultipactorthreshold,buttheexistingSEYmodelis deficientinsatisfyingtheneedsofaccuracyandconcisenessatthesametime.AnanalyticalmodelforSEYofmetalswaspresentedbyanalyzingtheescapingprobabilityofsecondaryelectronscombinedwiththemodifiedBetheenergylossequation.Furthermore,SEYmodelsforuncleanedandArion cleanedAgsampleswereobtainedbyfittingtheexperimentalresultswiththeanalyticalmodel.CalculationresultsshowthatthestandarddeviationbetweenSEYmodelsandexperimentalresultsofuncleanedandArioncleanedAgiswithin4%atdifferentincidentangles,whichindicatesthattheanalyticalmodelpresentedcanbeusedtoestablishtheaccurateSEYmodelofmetalsandcalculatemultipactorthresholdofspacehighpowermicrowavecomponentanddensityofelectroncloudinaccelerator. Related Articles | Metrics

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Transientcharacteristicsofsecondaryelectronyieldbasedonchargingbalancemode FENG Guo-Bao, LI Jun, CUI Wan-Zhao, LIU Chun-Liang, CAO Meng 2017, 37 (2):  24-31.  doi: 10.16708/j.cnki.1000-758X.2017.0030 Abstract ( 839 )   PDF (7304KB) ( 268 )   Save Theessentialrelationshipbetweensecondaryelectronsemissionand chargingstatesofdielectricwasinvestigatedbasedonchargingbalancemodewithnumericalsimulat ion.BothMonteCarloandfinitedifferencetimedomainalgorithmswereadoptedfornumericalsimulat ion， consideringelasticandinelasticessentialbetweenincidentelectronsandmaterialatomsduringscatte ringprocessandcalculatingdiffusion， driftandtrapeffectsofinternalcharges.Underdifferentchargingbalancemodes， thesecondaryelectronemissionandchargingstatesofdielectricontransientchange， internaldistributionsandsaturationvalueswereanalyzedandsimulated.Theresultsshowthatchargi ngbalancemodescanbedividedintothesecondaryelectron（SE）mode，theleakageelectron（LE） modeandthecombined（CO）mode.TheSEmodecorrespondstothesurfacechargingstate，whiletheLE modecorrespondstothedeepchargingstate.WhenthechargingbalancemodechangestowardsSEmod efromLEmode，boththesecondaryelectronyieldandthenegativesurfacepotentialincreases，while variationtrendsofthetotalchargingquantityandchargingtimeconstantpresenttobeopposite asaresultofbalancemodechange. Related Articles | Metrics

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Amodifiedmodelfortheemissionofsecondaryelectronsbylowenergyelectronimpact PENG Kai, LI Jing, ZHANG Ying-Jun, SU Chen, CUI Wan-Zhao 2017, 37 (2):  32-38.  doi: 10.16708/j.cnki.1000-758X.2017.0039 Abstract ( 746 )   PDF (2642KB) ( 694 )   Save Withthefurtherofstudyofthemultipactor,effectsoflowenergyelectronshadbecomemoreand moreimportant.Inordertosimulateandanalyzemultipactortheoryaccurately,onthebasisofresear chforsecondaryandbackscatteredelectronemissionmodel,anewmodelwasputforwardbased onsecondaryelectronyield(SEY),backscatteredelectronyield（BEY） andtheangleofelectronincidence.ConsideringthedifferenceofSEY,BEYoflowenergyelectron,a ndcompactingseveralsecondaryand backscatteredelectronyieldformulae,thenewmodelformultipact orhadabetterprecisionandapplicability.Finally,somediscussionandanalysiswasdoneforimprovingthecorrectnessandbroadeningthe applicationofthemodel. Related Articles | Metrics

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Dynamiccharacteristicsofsecondaryelectronemissionofdielectricmaterials ZHANG Xiu-Sheng, CAO Meng, WENG Ming, WANG Fang 2017, 37 (2):  39-47.  doi: 10.16708/j.cnki.1000-758X.2017.0038 Abstract ( 840 )   PDF (7703KB) ( 938 )   Save Theresearchondynamiccharacteristicsofdielectricmaterialsis animportantpartinthefieldofsecondaryelectronemission.Bynumericalsimulationmethod,amod eloftheeffectivesecondaryelectroncollectionefficiencywasestablished andtheeffectsofmeasuringparametersonthedynamiccharacteristicswerestudied.Theresultsshow thatspaceelectricfieldandcollectorstructurehassomecorrelationontheeffectivesecondarye lectroncollectorefficiency.Theincreaseofcollectorpotentialcanimprovetheeffectivesecondary electroncollectionefficiencyandthehalfwidthtimeofthedynamicprocesswillincreaselinearly. Inaddition,thecollectorstructurecanaffectthespaceelectricfield.Bydirectlyinfluencingthe collectionefficiency,spaceelectricfieldandcollectorstructureindirectlychangethesurfacecha rgetocausethechangeofdynamiccharacteristics.Theincidentbeamcandirectlyaffectthesurfac echargeaccumulationandmakesthehalfwidthtimeincrease ordecrease.Theresultshaveimportantscientificsignificanceforrevealingthedynamicprocessofch argedmaterialandpredictingtheexperimentthataccuratelymeasuringthesecondaryelectronemission coefficients. Related Articles | Metrics

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Secondaryelectronemissionpropertiesfromborondopeddiamondfilms LI Li-Li, DING Ming-Qing, GAO Yu-Juan, SHAO Wen-Sheng, FENG Jin-Jun 2017, 37 (2):  48-53.  doi: 10.16708/j.cnki.1000-758X.2017.0032 Abstract ( 863 )   PDF (3852KB) ( 691 )   Save Thecathodematerialsusedinelectronmultiplier，fieldemission cathodeandparticle/photondetectorhavetheproblemoflowsecondaryelectronemissionyieldand unstableemission.Tosolvethisproblem， differentboronconcentrationdiamondfilmsbymicrowaveplasmachemicalvapordepositionwereprepared .ThesurfaceofB-dopeddiamondfilmwastreatedbyHydrogenplasma.Thesecondaryelectronemissi on（SEE）fromB-dopeddiamondfilmswasinvestigated. Thescanningelectronmicroscopy（SEM）andtheRamanspectrumanalysiswereusedtoexaminethepropertiesoftheB-dopeddiamondfilm. ThemaximumSEEyieldupto18.3at1keVprimarybeamenergywasfoundundertheconditionthatthesampleswereleftinairforweeksandsubjecttonotreatmentpriortothemeasurement.Oxidationtreatmentdestroysnegativeelectronaffinity（NEA）whereasheatingupinvacuumsubstantiallybringsbackNEA.B-dopeddiamondfilmisexpectedtobeusedinelectronmultiplier，fieldemissioncathodeandparticle/photondetector. Related Articles | Metrics

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TechniqueforinhibitingsecondaryelectronemissionofsilverbasedonZnOarray HU Tian-Cun, CAO Meng, BAO Yan, ZHANG Yong-Hui, MA Jian-Zhong, CUI Wan-Zhao 2017, 37 (2):  54-60.  doi: 10.16708/j.cnki.1000-758X.2017.0034 Abstract ( 934 )   PDF (13052KB) ( 304 )   Save WithsatellitepayloadRFpowerincreasing,traditionalmethodsof inhibitingmultipactorareunabletomeettheneedsofhighpowersatellitepayloads.Reducingthe secondaryelectronemissioncoefficientofinternalsurfaceofhighpowerRFcomponentsisanimpor tantmethodforinhibitingmutipactor.Nanoscalesilvertrappingstructurewaspreparedbyconstructing nanodimensionZnOarrays,  andtheeffectsofpreparingmethodsofseedsandzincsaltconcentration onthegrowthofZnOarrayswerestudied.TheresultsshowthathomogeneousZnOarraysareobtain edonthesamplesurfacebyusingtheUVradiationforseedssynthesizationandincreasingzincsaltconcentration.TheeffectofpackingdensityofZnOarraysonsilverfilmsconstructionwasinvest igated.ItshowsthatlowdensityZnOarraysaresuitablefordepositionofsilveronthesurface ofZnOnanorods.Therefore,  thetechnologyforpreparationoftrapstructuresilverbasedonZnOarray swasobtained,andthemaximumsecondaryelectronemissioncoefficientofsilverdecreasedby36.3% . Related Articles | Metrics

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Improvingtheefficiencyofthecollectorofspacetravelingwavetubewithmicromachiningtechnology BAI Chun-Jiang, CUI Wan-Zhao, YE Ming, HE Yong-Ning 2017, 37 (2):  61-65.  doi: 10.16708/j.cnki.1000-758X.2017.0037 Abstract ( 729 )   PDF (3451KB) ( 832 )   Save Thesecondaryelectronyield (SEY) hasgreatinfluenceontheefficiencyofthecollectorofspacetravelingwavetube.Therefore, theefficiencyofcollectorwasimprovedbyreducingthesecondaryelectronyieldofthematerial′ssurfaceofcollector. TheOFHCcoppersamplewastreatedwithchemicaletching.Afterchemicaletching,somemicroporous arraystructureswereremainedonthesample.Thenthesecondaryelectronyieldofthesamplewasm easuredbythesecondaryelectronyieldmeasurementplatform.Andtheresultshowsthatcomparingwiththeoriginalsamplewhichisnottreated,themaximumofSEYdecreasesfrom1.33to0.96.And theSEYissuppressedwell.ThentheSEYcurvesobtainedfromSEYmeasurementplatformwereused  inthedesign ofSTWTcollector.TostudytheinfluenceoftheSEY,threecollectormodelswereusedtocalculate theefficiencyofthemodelswithsimulationsoftware.Itisverifiedthattheefficiencyofthe threecollectorsareimprovedfrom80.1%,57.5%,42.1%to82.55%,62.6%,59.2%,respectively.ThemethoddiscussedwillbehelpfulfortheSTWTdesign. Related Articles | Metrics

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Equivalentpowerdeterminationforsingleeventmulticarriermultipactorbasedona modifieddifferentialevolutionalgorithm WANG Xin-Bo, ZHANG Xiao-Ning, LI Yong-Dong, LIU Chun-Liang, WANG Rui, WEI Huan, RAN Li-Xin 2017, 37 (2):  66-72.  doi: 10.16708/j.cnki.1000-758X.2017.0033 Abstract ( 756 )   PDF (3302KB) ( 756 )   Save Multipactorisoneofthemostimportantfailure   effectsforthespacebornemicrowavecomponents.Withtherapiddevelopmentofwidebandcommunication satellitesystems,themulticarriermultipactor(MM) ispaidmoreandmoreattentions.Whilethedesigncriterionwithmicrowavecomponentsforsingle carrierRFsignalisexplicit,itiscontroversialformulticarriermultipactor.Amethodtodetermine equivalentpowerforthesingleeventmulticarriermultipactorusingthemodifieddifferentialevol utionalgorithmwaspresentedtoovercomethedisadvantagesoftheconventionalempiricalformula.The powerpropertiesforthemulticarriersynthesissignalswereanalyzed,andtheenergyin20electrontransittimewasgloballyoptimized.Ineachoptimization,quadratic  interpolationwasusedtofind thelocaloptimum,thentheglobaloptimumwasobtainedbyusingthemodifiedDifferentialEvolutio nalgorithm.Itistheworstcaseforallkindsofconfigurationsandtheoptimalaveragepowercanbeusedfortheequivalentpowerinthewidebandcomponentdesign.Theproposedmethodisdemonst ratedwiththeuniformamplitudeandequallyspacedfrequencies.Theproposedapproachisalsoable toprovidereasonableequivalentpowerformulticarriersignalswithnonuniformamplitudesorthe unequallyspacedfrequencies. Related Articles | Metrics

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Anovelsimulationmethodofmultipactorincomplexcomponentforsatelliteapplication LI Yun, CUI Wan-Zhao, ZHANG Hong-Tai, YIN Xin-She, WANG Hong-Guang, ZHANG Jian-Feng, HE Yong-Ning 2017, 37 (2):  73-80.  doi: 10.16708/j.cnki.1000-758X.2017.0040 Abstract ( 888 )   PDF (3025KB) ( 903 )   Save Withthedevelopmentofhighpowerandminiaturizationinsatellitepayload,accuratesimulationandthresholdanalysisformultipactorin   complexcomponentbecomesbottleneckproblem.Basedontheparticleincelltechnologyandthesecondaryelectronemissiontheory,athreedimensionalsimulationmethodformultipactorwaspresented.Thenumericalalgorithmwasselfconsistentsincetheinteractionbetweenelectromagneticfieldsandparticleswasproperlymodeled.Thegenerationofmultipactoris   visualized,  sothat adeepinsightintothephysicalmechanismsofthiseffectwasgained.Inordertovalidatethemethod,multipactionintheimpedancetransformerwasstudied.Byanalyzingtheevolutionoftheelectronnumbersobtainedbyourmethod,multipactorthresholdsofthesecomponentswereestimatedandthemostsensitivepositionswheremultipactoroccurswerevisualized.Theresultsshowgoodagreementwiththeexperimentalresultsandthesimulationerrorislessthan1.2dB. Related Articles | Metrics

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econdaryelectronsaccumulationinspacemicrowavecomponentsanditsrelationshipwithtransmissionproperties ZHANG Heng, CUI Wan-Zhao, LI Yun, WANG Xin-Bo, YANG Jing 2017, 37 (2):  81-88.  doi: 10.16708/j.cnki.1000-758X.2017.0024 Abstract ( 751 )   PDF (5414KB) ( 789 )   Save Therelationshipbetweentheaccumulationofmultipactingelectronsandthevariationofthetransmissionpropertiesinmicrowavecomponentswasstudied.  Anequivalentmediamodelwasproposedtodescribetheelectronaccumulationduringmultipactor,whereeffectsoftheelectrons′accumulationwereapproximatedasamediawithspecialrelativepermittivity.Thevalueofthespecialrelativepermittivitywascalculatedequivalentlycorrespondingtotheelectrondensity.Simulationandcalculationresultsindicatethatthetransmissionpropertiesofthemicrowavecomponentsremainunchangedwhenthedensityofelectronsincreasedfrom0/m3to1×1016/m3duringmultipactor.However,thereturnlossinthepassbandfrequenciesdropped15dBwhentheelectrondensityreached1×1017/m3.Astheincreasingoftheelectrondensity,thereflectionofelectromagneticwavecausedby“equivalent  media”increasedrapidlywhichmadethetransmissionpropertiesofthemicrowavecomponentsdeterioratessharply.Thesimulationwascoincidewiththeresultsoftheoreticalanalysis,whichindicatedthatthetransmissionwasevencutoffwhenthedensityofelectronsincreasedtothemagnitudeof4×1017/m3.Inaddition,whentheelectrondensityreached4×1017/m3(inthefrequencyrangeof2.5~5GHz),therelativepermittivityofthe“equivalentmedia”wasnegativeandthetransmissioncutoff.Thisresearchishelpfultounderstandthemechanismandtheelectricalcharacteristicschangesofmicrowavecomponentsduetomultipactor,providinganeffectivetheoreticalprincipleformultipactorsuppression. Related Articles | Metrics

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Multipactorsimulationalgorithmbasedonfinitedifferenceintimedomain ZHANG Jian-Feng, YOU Jian-Wei, WANG Hong-Guang, LI Yun, CUI Wan-Zhao, CUI Tie-Jun 2017, 37 (2):  89-95.  doi: 10.16708/j.cnki.1000-758X.2017.0036 Abstract ( 778 )   PDF (5722KB) ( 1191 )   Save Traditionalmultipactorpredictionmethodbasedonplaneapproximationisfastbutinaccurate,whichcannotmeettheelectricalperformancedesignrequirementswhendevicesbecomemoreandmorecomplex.Thefinitedifferencetimedomainalgorithmisoneofthemostpopularmethodsinthecomputationalelectromagnetics.TheparticletracingalgorithmisanumericalmethodbasedontheNewton'sforcelaw. Thetwoalgorithmscanbeselfconsistentlycombinedbythediscretemeshinbothtimeandspacedomains,whichcanbeusedtopredictthemultipactorbreakdownthreshold.Inaddition,theconformalandparallelizingtechnologieswerewellstudied.Multipactorbreakdownofclassicmicrowavedevicewasanalyzedbythedevelopedalgorithm.Theerroris0.3dBcomparedwiththeexperimentsandthemaximumparallelefficiencyis83%,whichdemonstratetheaccuracyandefficiencyofthealgorithm. Related Articles | Metrics

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ExperimentalresearchonanSbandinjectlockingmagnetronformultipactordischargetest CHEN Xiao-Jie, LIU Zhen-Long, LIU Chang-Jun 2017, 37 (2):  96-102.  doi: 10.16708/j.cnki.1000-758X.2017.0025 Abstract ( 858 )   PDF (7779KB) ( 339 )   Save S-bandinject-lockingmagnetronexperimentforthegroundmultipactordischargetestwasproposedforthelargepowermicrowavesourceofsatellite.Thedirectlyproportionalrelationbetweenthemagnetroninject-lockingbandwidthandtheinjectionratiowasstudiedbasedontheinject-lockingcontinuouswavemagnetrontheory.Themagnetronoutputpowervariedfrom389Wto1150Wbytuningthemagnetronanodecurrent.TheinjectionlockingbandwidthatSbandofthe1kWcontinuouswavemagnetronwasbroadenedto12.6MHzbyincreasingtheinjectedpower.Dual-frequencyinject-locking，spurioussuppressionandpowerdistributionwereobservedinthetwo-toneinjectionexperiments. Related Articles | Metrics

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Studyonlife-testofM-typeimpregnatedcathodeforspaceTWT SHAO Wen-Sheng, LI Ji, YU Zhi-Qiang, CHENG Cheng, ZHANG Ke, WANG Hui, WANG Li-Shan 2017, 37 (2):  103-107.  doi: 10.16708/j.cnki.1000-758X.2017.0035 Abstract ( 922 )   PDF (6596KB) ( 857 )   Save Spacetravellingwavetube（STWT）withlonglifeplaysanimportantroleonthepoweramplifierforsatellitecommunicationsystem.ThelifeoftheSTWTismainlyrestrictedbythecathodelife.InordertoensurethattheSTWTcanhavealonginorbitoperatingtime,itisnecessarytocarryoutplentyexperimentalresearchesonthelifeofSTWTcathode,andtopredictthelifeoftheSTWTcathode.Theaccumulatinglifetesttimeis1823080hoursfor50electronguns,thelongestlifetesttimeisover65411hours.Thelifepredictionmodelwasbuiltonthebasisofthechangeoftheworkfunctionduringthelifetime.Thepredictinglifeismorethan43yearswhenthecathodeisdrawnacurrentdensityof1A/cm2at960℃b (℃b: brightnesstemperature),itismorethan22yearsat980℃b,  anditismorethan15yearsat1000℃b.ThepredictinglifeshowsthatthelonglifeSTWTcathodecanmeettherequirementsofthesatellitecommunicationsystem. Related Articles | Metrics

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StudyoncommunicationperformanceimprovementusingLDPCcodeunderpassiveintermodulationinterference FANG Tian-Qi, HU Tian-Cun, TIAN Lu, LIU Jian-Chun 2017, 37 (2):  108-113.  doi: 10.16708/j.cnki.1000-758X.2017.0029 Abstract ( 771 )   PDF (3886KB) ( 994 )   Save Duetothetimevaryinganddiscontinuouscharacteristicsofpassiveintermodulationinterferencesignals，anovelmethodbyusingerrorcorrectingLDPCcodewasproposedtoreducetheimpactofpassiveintermodulationinterference.TheLDPCcodinganddecodingschemewasdesignedandthedecodingpartwasemphasized.Thenormalizedminsumalgorithmbasedonrowmessagepassingwasadoptedforitslowiterationtime.Pulsesat10%dutycyclewereusedtosimulatethepassiveintermodulationinterference.Thesimulationresultsshowthatthecodinggainisabout8.2dBwhentheBERis3.1dB. TheexperimentalresultsshowthattheBERis0.00269andSIRgainreaches10dBwhenSIRis2dB. Related Articles | Metrics