The maximum theoretical efficiency of constant inductance gradient electromagnetic launchers

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1、608IEEETRANSACTIONSONPLASMASCIENCE,VOL.37,NO.4,APRIL2009TheMaximumTheoreticalEfficiencyofConstantInductanceGradientElectromagneticLaunchersThomasG.Engel,SeniorMember,IEEE,JesseM.Neri,andMichaelJ.VerackaAbstractThemaximumtheoreticalefficiencyofconstanti

2、n-ductancegradientelectromagneticlaunchers(EMLs)isanalyzedanddiscussed.ThemaximumtheoreticalefficiencyisaparameterneededtocalculatetheEMLsefficiency.ConstantinductancegradientEMLsincludetheconventionalrailgun,theaugmentedrailgun,andtheconventionalhelic

3、allauncher.ThemaximumtheoreticalefficiencyofanEMLisdependentonitsgeometryandthemanner,ormode,inwhichitispowered.Inthelosslesscase,theconventionalrailgun,theaugmentedrailgun,andtheconven-tionalhelicallauncherarecapableof50%maximumefficiencywhenoperating

4、inconstantcurrent(CC)mode.Conventionalandaugmentedrailgunscanachieve100%maximumefficiencywhenoperatinginzeroexit-currentmode.Whilezeroexit-currentmodepromoteshighefficiency,thismodecanreduceEMLlifetimesinceitrequirescurrentlevelsmuchhigherthanthosefoun

5、dinCCmode.Thehigh-efficiencyhelicallauncher,presentedandana-lyzedhereforthefirsttime,combines100%maximumtheoreticalefficiencywiththelow-currentbenefitsofconstant-currentmode.IndexTermsCoilguns,electromagneticlaunching,linearmotors,railguns.I.INTRODUCTION

6、LECTROMAGNETIClaunchers(EMLs)weredevelopedEintheU.S.asearlyas1845[1].WhilemanydifferenttypesofEMLshavebeendevelopedsincethattime[2],re-searchanddevelopmenteffortsoverthelastseveraldecadeshavelargelyconcentratedonconstantinductancegradientEMLssuchasth

7、econventionalrailgun,theaugmentedrailgun,andtheconventionalhelicallaunchershowninFig.1.TheseeffortshaveproducedagoodunderstandingofelectromagneticforceandmagnetomotiveforceproductioninthesedevicesFig.1.ConstantgradientEMLgeometriesofthe(a)conventiona

8、lrailgun,(b)augmentedrailgun,and(c)conventionalhelicallauncher.(magnetomotiveforceisoftenreferredtoasthebackEMForback-voltage).Efficiency,ontheotherhand,hasreceived[2]–[5]ornarrowlyfocusedwithchangesinefficiencyfromlessattentionandisnotaswellunderstood