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FabricationandFlyerDrivingCapabilityCharacterisationofanIntegratedExplodingFoilInitiator         8 9 5

         tionprocess,whileithasbeencaughtupbytheflyerfrom
                #
         sample2 atthe100nsfrom thestartpoint.Accordingtothe  4.3  InfluencesofBarrelLengthontheFlyerAcceleration
         sameinputenergy,thethinnerfoilprovidesgreaterenergy       Capability
         densitywhilethethickfoilwouldcreatemoreplasmaforac    Thevelocityattheimpactpointisoneofthekeyfactors
         celerationrelatively.Thegreaterenergydensityproducesa  fortheinitiation,andtheimpactpointofflyer′sflightisdeter
         fasterelectricalburstandbetterinitialacceleration,whilethe  minedbythelengthofbarrel.Anunusualphenomenonwas
         largerquantityofplasmaprovidesamorecontinuousaccelera  foundthatthemeanthresholdvoltageofEFIsincreasesabout
                                                                                                           [9]
         tion.Thecombinationofthesefactorscouldleadtothephe  18% asthebarrellengthextendsfrom 0.2mm to0.4mm  .
         nomenathatexhibitedintheFig.8.                       Fortheinvestigationofflyers′accelerationprocessinthesetwo
                                                              kindsofbarrel,we′vesetanothertestfortheflyervelocity
         Table2 ThesampleparametersofEFIfoilthicknesstest     PDVdiagnostic;theparametersarelistedinTable3.
               foil     barrel         flyer
                               barrel           flyer
         sample thickness  length      thickness              Table3 ThesampleparametersofEFIbarrellengthtest
                               material         material
               / μ m     /mm           / μ m
                                                                    foil     barrel        flyer
         1 #   3        0.4    Su8     25       paryleneC    sample thickness  length  barrel  thickness  flyer
         2 #   4        0.4    Su8     25       paryleneC          / μ m    /mm    material  / μ m  material
                                                              1 #  4         0.2    Su8    25        paryleneC
                                                               #
                                                              2    4         0.4    Su8    25        paryleneC
                                                                TheresultofthePDV diagnosticisillustratedinFig.10,
                                                              whichshowsthatthereisn′tanydistinctdivergencebetween
                                                                                      #
                                                                                            #
                                                              thevelocityprofileofsample1 and2.Theflyervelocityat
                                                                                                        #
                                                              theflightdistanceof0.2mm couldreachto92% (1 )and
                                                                   #
                                                             88%(2)oftheultimatevelocitydetected,whichisconsist
                                                                                           [10]
                                                              entwiththevelocityprofileofChow  ,Thevelocityatthe
                                                                                        #
                                                                           #
                                                              impactpointof1(0.2mm)and2(0.4mm)arerespectively
                                                                       -1  #              -1  #
         Fig.8  Theacclerationprofileofflyersdrivenbyexplodingfoilwith  3790m· s (1 ) and4129 m· s (2 ).Withthebarrel
         differentthickness                                   lengthextendfrom 0.2mm to0.4mm;thevelocityatimpact
                                                              pointhasincreasedabout9%.
           Toinvestigatethevelocityatimpactpoint(thevelocityat
         thebarrelexit) during the flyers′flight,the flyervelocity
         distanceprofilecouldbeobtainedfrom theintegralofvelocity
         timehistoryinFig.8.
           AsitillustratedinFig.9,Theflyers′velocityattheimpact
                                                   #
                                               -1
         point(0.4 mm) are respectively3906 m · s (1 ) and
                     #
                 -1
         4129m·s (2 ),thedivergenceofthem ismerelyabout
         5%,whichisconsistentwiththetestsconductedbyJunSik
         Hwang,thatthemean firingenergystaysin acomparative
         level,whenthefoilthicknessrangefrom 3μ m to6μ m [8] .
                                                              Fig.10 ThevelocitydisplacementprofileofEFIassembledwithdiffer
                                                              entbarrellength

                                                                AsitshowninFig.10thatthevelocityattheimpactpoint
                                                              indeedincreasedasthebarrellengthextended,whichcould
                                                              deduced thatthe increasing ofthe mean threshold voltage
                                                              shouldnotowntotheflyervelocity.
                                                                 Actually,otherfactorsmayalsoassociatewiththeflyer
                                                              initiationenergy,suchasimpactangle,impactarea,andim
                                                              pactduration. Afterthe vaporization ofmetalbridge, the
         Fig.9 ThevelocitydisplacementprofileofEFIassembledwithdiffer  flyer′sdrivingpressuredecreasessharplyfrom thepeaktoa
         entfoilthickness                                     relativelylow level.Undertheinfluenceofthedrivingpres


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