简介：Significantelectromagneticpulses(EMP)canbegeneratedbytheintensivelaserirradiatingsolidtargetsininertialconfinementfusion(ICF).ToevaluatetheEMPintensityanddistributioninandoutsidethelaserchamber,wedesignedandfabricatedadisconeantennawithultra-widebandsofover10GHz.Thereturnloss(S11parameter)ofthisantennawasbelow-10dBandcouldevenachieveunder-30dBat3.1GHz.TheEMPintensityinthisstudyat80cmand40cmawayfromthetargetchambercenter(TCC)reached400kV/mand2000kV/m.ThecurrentresultsareexpectedtoofferpreliminaryinformationtostudyphysicsregardinglaserplasmainteractionsandwillalsolayexperimentalfoundationforEMIshieldingdesigntoprotectvariousdiagnostics.

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简介：Inthepaper,relativisticfilamentationofintenselaserbeamininhomogeneousplasmaisinvestigatedbasedonthenonparaxialregiontheory.Theresultsshowthat,relativisticnonlinearityplaysamainroleinbeamfilamentation,andplasmainhomogeneityfurtherreinforcesthebeamfilamentation.Thecombinationeffectsofrelativisticnonlinearityandplasmainhomogeneitycangenerateparticularlyintenseandshortpulselaser.However,plasmainhomogeneityleadstoobviousfilamentationinstability.

简介：ThepumpedsystemoftheXeC1excimerlaserhasbeendesignedandappliedtoanalyzeUVXeCllaserspectroscopycharacteristics.UndertheproportionofmixedgasofHCl:Xe:He=0.1%:1%:98.9%,excimerlaserlightwasgeneratedbystableglowdischargeprocess.Thelaserspectrum,pulseduration,andlaserpowerpropertieswereobtained.TheresultshowsthatthisXeClexcimerlaserexhibitsuniquespectralproperties,withtwopeaksbetween307.7nmand308.5nmathighpressurewithapumpedpowerof1.3959MW/cm~3.ThetransitionreliesonthestrongesttransitionsbetweenB-XandC-X.Themaximum-intensitytransitionofspectroscopyisBtoXenergylevels.Thelaserparametersareasfollows:minimaldurationof15.42ns,arepetitionratefrom0.5Hzto5Hz,singlepulsestablepowerof400mJ,andbeamdivergenceangleof3mrad.ThelasercanbeusedtostudyUVspectroscopy,laserablationsamplingandsputteredpinnateform.

简介：OpticalemissionfromTiO_2plasma,generatedbyananosecondlaserisspectroscop-icallyanalysed.Themainchemicalspeciesareidentifiedandthespatio-temporaldistributionoftheplasmaparameterssuchaselectrontemperatureanddensityarecharacterizedbasedonthestudyofspectraldistributionofthelineintensitiesandtheirbroadeningcharacteristics.Thepa-rametersoflaserinducedplasmavaryquicklyowingtoitsexpansionatlowbackgroundpressureandthepossibledeviationsfromlocalthermodynamicequilibriumconditionsaretestedtoshowitsvalidity.

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简介：The45°scatteringofafemtosecond(60fs)intenselaserpulsewitha20nmFWHM(thefullwidthathalfmaximum)spectrumcenteredat790nmhasbeenstudiedexperimentallywhilefocusedinargonclustersatintensity～1016W/cra2.Scatteringspectraunderdifferentbackingpressuresandlaser-plasmainteractionlengthswereobtained,whichshowedspectralblueshifting,beamrefractionandcomplexmodulation.Theseionization-inducedeffectsrevealthemodulationoflaserpulsespropagatinginplasmasandtheexistingobstacleinlaserclusterinteractionathighlaserintensityandhighelectrondensity.

简介：Inthiswork,laserinducedtungstenplasmahasbeeninvestigatedintheabsenceandpresenceof0.6Tstatictransversemagneticfieldatatmosphericpressureinair.Thespectroscopiccharacterizationoflaserinducedtungstenplasmawasexperimentallystudiedusingspace-resolvedemissionspectroscopy.Theatomicemissionlinesoftungstenshowedasignificantenhancementinthepresenceofamagneticfield,whiletheionicemissionlinesoftungstenpresentedlittlechange.Temporalvariationoftheopticalemissionlinesoftungstenindicatedthattheatomicemissiontimeinthepresenceofamagneticfieldwaslongerthanthatintheabsenceofamagneticfield,whilenosignificantchangesoccurredfortheionicemissiontime.Thespatialresolutionofopticalemissionlinesoftungstendemonstratedthatthespatialdistributionofatomsandionswereseparated.Theinfluenceofamagneticfieldonthespatialdistributionofatomswasremarkable,whereasthespatialdistributionofionswaslittleinfluencedbythemagneticfield.Thedifferentbehaviorsbetweenionsandatomswithandwithoutmagneticfieldinairwererelatedtothevariousatomicprocessesespeciallytheelectronsandionsrecombinationprocessduringtheplasmaexpansionandcoolingprocess.

简介：X-rayThomsonscatteringtechniquefordiagnosingdenseplasmawasdemonstratedonShenguang-Πlaserfacility.Laserplasmax-raysourceoftitaniumHe-αlines(～4.75keV),generatedbylaserbeam(1.5kJ/527nm/2ns)heatedtitaniumthinfoil,wasusedasx-rayprobebeam.Thex-rayprobewasthenscatteredbycoldCHfoamcolumnof1g/cm3density.Thescatteredradiationat90wasdiffractedbypolyethyleneterephthalate(PET)crystalandrecordedonx-raycharge-coupleddevice.Well-definedscatteringspectrawereobtainedwithgoodsignaltonoiseratio.

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简介：Thesurfaceshapeofliquidwateriswellcontrolledduringnanosecondpulselaserablationplasmapropulsion.Inthisstudy,wemeasuredtheeffectoftheshapeonthecouplingcoefficientandthespecificimpulse.Wefoundthatthecouplingcoefficientandspecificimpulsecouldbeoptimizedbyvaryingthesurfaceconvexity.Basedontheanalysisofthesurfaceradiuscurvature,wedemonstratethattheconvexsurfacechangesthelaserfocalpositionstoachievehighefficiency.

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简介：Laser-inducedbreakdownspectroscopy(LIBS)wasexaminedtodetectatracesubstanceadheredontoAlalloysforthesurfaceinspectionofmaterialstobeadhesivelybonded.AsanexampleofSicontamination,siliconeoilwasemployedandsprayedontosubstrateswithacontrolledsurfaceconcentration.LIBSmeasurementsemployingnanosecondUVpulses(λ=266nm)andanoff-axisemissioncollectionsystemwithdifferentdetectingheightswereperformed.Becausesurfacecontaminantsareinvolvedintheplasmaformedbylaserablationofthesubstrates,therelativecontributionofthesurfacecontaminantsandthesubstratestotheplasmaemissioncouldbechangeddependingontheconditionsforplasmaformation.Thelimitofdetection(LOD)wasevaluatedunderseveraldetectingconditionsforinvestigatingthefactorsthataffectedtheLOD.Asignificantfactorwasthestandarddeviationvaluesofsignalintensitiesobtainedforthecleansubstrates.Thisvaluevarieddependingonthemeasurementconditions.FortheAlalloy(A6061),thesmallestLODobtainedwas0.529μg·cm^-2.Furthermore,animprovedLOD(0.299μg·cm^-2)wasobtainedfortheAlalloywithalowerSicontent.

简介：Laser-inducedbreakdownspectroscopy(LIBS)wasdevelopedtodetectaluminuminnickel-basedsuperalloys(K417,GH4033,DZ125L,(?)742y)usinganon-intensified,non-gated,low-costdetectionsystem.TheprecisionofLIBSdependsstronglyontheexperimentalconditions.ThecalibrationcurvesofA1(I)394.4nmandA1(I)396.2nmundertheoptimumexperimentalparametersarepresented.Finallythelimitofdetection(LOD)foraluminumiscalculatedfromtheexperimentaldata,whichisintherangeof0.09%to0.1%byweight.

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简介：Accordingtothemultipleresearchesinthelastcoupleofyears,laser-inducedbreakdownspectroscopy(LIBS)hasshownagreatpotentialforrapidanalysisinsteelindustry.Nevertheless,theaccuracyandprecisionmaybelimitedbycomplexmatrixeffectandself-absorptioneffectofLIBSseriously.Anovelmultivariatecalibrationmethodbasedongeneticalgorithm-kernelextremelearningmachine(GA-KELM)isproposedforquantitativeanalysisofmultipleelements(Si,Mn,Cr,Ni,V,Ti,Cu,Mo)inforty-sevencertifiedsteelandironsamples.First,thestandardizedpeakintensitiesofselectedspectralinesareusedastheinputofmodel.Then,thegeneticalgorithmisadoptedtooptimizethemodelparametersduetoitsobviouscapabilityinfindingtheglobaloptimumsolution.Basedonthesetwostepsabove,thekernelmethodisintroducedtocreatekernelmatrixwhichisusedtoreplacethehiddenlayer’soutputmatrix.Finally,theleastsquareisappliedtocalculatethemodel’soutputweight.InordertoverifythepredictivecapabilityoftheGA-KELMmodel,theR-squarefactor(R2),Root-mean-squareErrorsofCalibration(RMSEC),Root-mean-squareErrorsofPrediction(RMSEP)ofGA-KELMmodelarecomparedwiththetraditionalPLSalgorithm,respectively.TheresultsconfirmthatGA-KELMcanreducetheinterferencefrommatrixeffectandself-absorptioneffectandissuitableformulti-elementscalibrationofLIBS.

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简介：Highresolutionspectralanalysisoflithiumplasmaformedbysingleanddoublelaserablationhasbeenundertakentounderstandtheplume-laserinteraction,especiallyattheearlystagesoftheplasmaplume.Inordertoidentifydifferentatomicprocessesinevolvingplasma,timeresolvedspectralemissionstudiesatdifferentinter-pulsedelayshavebeenperformedforionicandneutrallithiumlinesemittingfromdifferentlevels.Alongwiththeenhancementinemissionintensity,alargelinebroadeningandspectralshift,especiallyinthecaseofexcitedstatetransitionLiI610.3nmhavebeenobservedinthepresenceofthesecondpulse.Thisbroadeningandshiftgraduallydecreasewithincreasingtimedelay.Anotherinterestingfeatureistheappearanceofamulti-componentstructureintheioniclineat548.4nmandthesecomponentschangeconverselyintoasinglestructureatthelaterstagesoftheplasma.Themulti-componentstructuresarecorrelatedwiththepresenceofdifferentvelocity(temperature)distributionsinnon-LTEconditions.AtomicanalysesbycomputingphotonemissivitycoefficientswithanADAScodehavebeenusedtoidentifytheaboveprocesses.

简介：Laser-inducedbreakdownspectroscopy(LIBS)hasattractedextensiveattentionasanewtechniqueforin-situmarineapplication.Inthiswork,theinfluenceofdeep-seahighpressureenvironmentonLIBSsignalswasinvestigatedbyusingacompactLIBS-seasystemdevelopedbyOceanUniversityofChinaforthein-situchemicalanalysisofseawater.TheresultsfromthefieldmeasurementsshowthattheliquidpressurehasasignificanteffectontheLIBSsignals.Higherpeakintensityandlargerlinebroadeningwereobtainedasthepressureincreases.BycomparingthevariationsofthetemperatureandsalinitywiththeLIBSsignals,aweakcorrelationbetweenthemcanbeobserved.Underhighpressureconditions,theoptimallaserenergywashigherthanthatinairenvironment.Whenthelaserenergyexceeded17mJ,theeffectoflaserenergyonthesignalintensityweakened.Thesignalintensitydecreasesgraduallyatlargerdelays.TheobtainedresultsverifiedthefeasibilityoftheLIBStechniqueforthedeep-seain-situdetection,andwehopethistechnologycancontributetosurveyingmoredeep-seaenvironmentssuchasthehydrothermalventregions.