direct observation of spatiotemporal dynamics of short electron bunches in storage rings 2017 c. evain学术.pdf

该【direct observation of spatiotemporal dynamics of short electron bunches in storage rings 2017 c. evain学术 】是由【湘云】上传分享，文档一共【6】页，该文档可以免费在线阅读，需要了解更多关于【direct observation of spatiotemporal dynamics of short electron bunches in storage rings 2017 c. evain学术 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。weekendingPRL118,054801(2017),1,*,,,1M.-,3J.-,,,,AtomesetMolécules,RS8523Centred’étudesetdeRecherchesLasersetApplications,RS2416,UniversitédesSciencesetTechnologiesdeLille,F-59655Villeneuved’AscqCedex,France2Elettra-rieste,StradaStatale14-km163,5inAREASciencePark,34149Basovizza,Trieste,Italy3SynchrotronSOLEIL,SaintAubin,BP34,91192Gif-sur-Yvette,France(Received28July2016;published2February2017)Inrecentsynchrotronradiationfacilities,theuseofshort(picosecond),,weobserveatrainofidenticalTHzpulses(abroadbandTerahertzcomb),alargepartoftheemissionisdominatedbydriftingstructures,-:.054801Inlastgenerationstorageringfacilities,eCSRelectricfieldpulseshapes,essiveshotsatpossibletoproducepulsesofcoherentsynchrotronradi-ultrahighrepetitionrates[24](seealsoRefs.[25–27]foration(CSR),withpowersthatexceedclassical(incoherent)otherphotonic-elerationstrategies).synchrotronradiationbyfactorsgreaterthan10000[1–7],Nevertheless,thelimitedsensitivityofthesenewhigh-bs[8,9].repetition-ratepicoseconddetectorslimitedexperimentalAprivilegedwayforobtainingthistypeofemissionwithinvestigationofTHzsignalstospecialconditionsofhighthestabilityrequiredforusers,(picosecond)electroncorrespondstothehighestpossiblepeakpowers,butalsotobunches[2,6,7,10–14].Asthemainidea,ifthelongitudinalstronglyunstableoperation[18,24].Thus,characterizationponentsatofCSRpulseshapedynamicsremainedanopenquestionforterahertzfrequencies,anintenseandstableemissionofshort(picosecondscale)andlow-chargeelectronbunches,coherentterahertzradiationisgenerallyexpectedinbend-.,onditionswhereexploitingthisfundamen-elerators,,asaTHzsource,,wepresenttheactualshapes(theelectriccomplicatedbyaphysicalphenomenonofveryfundamentalfieldevolution,includingenvelopeandcarrier)oftheTHznature:theinteractionofelectronbuncheswiththeirCSRpulsesemittedinshortbunchoperationinastorageownemittedradiationleadstoaspatiotemporalinstability,:high-microstructuresatthemillimeterscale[16–18].Inturn,thesesensitivityelectro-opticsampling[15,28],theinterplaybetweenrequiredsignal-to-noiseratiowithpicosecondresolution,thesetwomodesofemission(.,fromthe“shortness”ofandtheso-calledtime-stretchstrategy[22–24],whichtheelectronbunchesandfromthespontaneouslyformedenablessingle-shotrecordingsatultrahighacquisitionmicrostructures),-However,itisonlyrecentlythatdirectexperimentalcallyevolvingpulses:themicrobunchinginstablitythresh-observationoftheemittedTHzelectricfieldpulseshapesold,,electro-optic[16,17,29].WealsoshowthatnumericalintegrationofepossibleinstorageringseitherfortheVlasov-Fokker-PlanckequationreproducesthemainrecordingCSRpulses[19,20],andelectronbunchnear-[21].Thentheso-calledphotonictime-stretchTheexperimenthasbeenperformedattheSOLEILstrategy[22,23]openedthewaytodirectrecordingsofstorageringinaso-calledlow--9007=17=118(5)=054801(6)054801-1?2017AmericanPhysicalSocietyweekendingPRL118,054801(2017)PHYSICALREVIEWLETTERS3FEBRUARY2017coherentTHzpulses(a)highsensitivity(c)relativistictime-stretch5pselectronbuncheselectro-optic-samplingTHzCSRpulsessystemPM?berSynchrotronSOLEILstorageringP4ZnSe2km()OAPMGaPBrewsterPM?berplatesQWPrevolutionperiod:?berlaser(1030nm,12nJ)(b)150VOAdelayreplicaofthepulses100atnanosecondscalebalanced50photodetector0GHzoscilloscopebunchcharge(pC).(a)(209intheexperiment:essivebunchesandoneisolatedbunch).TheTHzcoherentsynchrotronradiationpulsesemittedinabendingarerecordedinsingleshotwithpicosecondresolutionattheTHz/IRAILESbeamline,usinghigh-sensitivityphotonictime-stretchelectro-opticssampling.(b).(c)Photonictimestretchelectro--maintaining(PM)fibers(PM980).Greenlinesaresinglemodefibers(HI1060).Fiberedpolarizingbeamsplitter(PBS),off-axisparabolicmirror(OAPM),polarizer(P),5mmlong,[110]-cutgalliumphosphidecrystal(GaP),quarter-waveplate(QWP),variableopticalattenuator(VOA),andadjustabledelayline(delay).ThebalanceddetectorisanDCS-(seetextandRef.[15]).ThepolarizationsofthelaserandTHzfieldareparallelandorientedalongthe??110?axisoftheGaPcrystal(andperemptorytothefigureplane).TheQWPisadjustedat45°(ofaboutpulse,thatistemporallymagnified,[30]),.[31].Theacquisitionwindowpis??????oftheorderof15ps,bunches,=cm=Hzat300GHzinthedifferentcharges[(b)].Thisallowsinvestigationsasaelectro-rystal(.,=cmoverthe0–300GHzfunctionofbunchchargebysimplystudyingtheemissionband).SincethefrequencyrangeoftheCSRpulsesisofeachindividualelectronbunch,withoutchangeofthetypicallyinthe150–600GHzrange[6,14],––65Ziline,usingaphotonictime-stretchelectro-opticsamplingoscilloscope(withan—overdimensioned—30GHzband-setup,whichisspeciallydesignedforhighsensitivitywidth),andtheacquireddataarenumericallylow-pass[(c)].posedoftwoparts,-longtimeseries,whicharepartlyintertwined(seealsoRef.[31]fordetails).whichcorrespondstoapproximately2500turnsinthestorageThefirstpartisasingle-shotEOS[32,33]-shotrecordingsoftheTHzCSRpulsesthedesigndeveloppedatSLS[20],FLASH[34],andANKA(electricfieldvstime)[21],,wealsorepresentedAsakeypointforreachingtherequiredhighsensitivity,wethepulseseriesinacolorscalediagram,versustimeandfollowthespecialstrategyrecentlypublishedbyAhmed,numberofturns,(a)–3(c),forthreeSavolainen,andHamm[15,28],,(c).,thedataevidencethecoherentemissionacquisitionrates,weassociatedthisEOSsetupwiththeso-urfromthe“shortness”[36].Thisprocessisdirectlyvisiblebelowtheandco-workers[22,35].Thechirpedlaserpulsescontainingmicrobunchinginstabilitythreshold[(a)].TheemissiontheTHzpulseshapeinformationarestretchedwithina2km-occursasafew-periodcoherentTHzpulses,withoutlongfiber[23],,wethusobtaina“replica”b[8,9].054801-2weekendingPRL118,054801(2017)++?1(t)(Volt)turnn+1VEOSetT?VEOSetT;?n0Vturnn0EOS--opticsamplingsignalofthe051015202530THzpulses.-timet(ps)-shotelectro-?850VnetT(correspondingtotheTHzCSRelectricfieldemittedavg(with)(g),3(h),3(i).byoneelectronbunch,ponentislinkedtotheshort-bunchmodering).Theelectronchargeis75pC[seconddot,.,,.,(b)].Forclarity,thesignalsareshiftedverticallyareused[18,24].,itisalsopossibletoreconstructtheEnturn-by-turnevolutionoftheTHzpulseenergyTHz,withurswhenthechargeexceedstheZt2so-calledmicrobunchinginstabilitythreshold[(b),En?jVEOSetTj2dt;eTTHzn23(c)].AnimportantpartoftheTHzradiationisthenemittedt1intheformofanoscillation,-,whicharecontinuouslyThissignalcorrespondstothesignalthatwouldberecordedmovinginsidetheelectronbunch,asdescribedinthewithastandard“slow”detector[(d)–3(f)].,thefirstpermitsustoconfirminaverydirectwaythatthemodulationprocess,.,thecoherentemissionduetothebunchintheTHzsignal,(e)andshortness,isexpectedtoexistabovethemicrobunchingwhichhadbeenobservedinnumerousstudies[12,37–42],-(b),3(c)canbeevidencedstructuresinthebunch[(b)].EOSEOSEOSVn(t)(mV)Vn(t)(mV)Vn(t)(mV)010050100(a)(b)50(c)2550000200-25-50-50-50-100-100pulsepulsepulse400energy(.)energy(.)energy(.)(d)(e)(f)round-tripsn60080020(g)048(h)048(i)048(t)(mV)0EOS-20avgV051015200510152005101520timet(ps)timet(ps)timet(ps).(a)–(c)Terahertzpulsesshapes[electro-opticsamplingsignalVnetT]vsround-(a)–(c)correspondtobunchchargesofQ?42,75,and118pC,respectively[.,bunchnumbers61,65,(b)].Eachhorizontalcutcorrespondstotheelectricfieldshape().(d)–(f)Pulseenergyversusturnnumber(integrationoverthetimeofthesquareoftheEOSsignal,andlow-passfilteredat50kHz).HorizontalblacklinesanddotsEOSplacedforvisualguide.(g)–(i)Averageelectro-(a)and(b)arerecordedsimultaneously(.,theycorrespondtoasingleoscilloscoperecording).054801-3weekendingPRL118,054801(2017)PHYSICALREVIEWLETTERS3FEBRUARY2017Wehavethenperformednumericalintegrationsofanalytictimet(ps)timet(ps)timet(ps)50-550-550-5models,parisonwiththeseexperimentaldata3(obtainedforthefirsttimeinashort-bunchmode),andalso(a)(b)(c):0theone-dimensionalVlasov-Fokker-PlanckmodelwithtailheadshieldedCSRwakefield[17].Theevolutionoftheelectronrelativeenergyp-3densityisdescribedbythephasespacedistribution-202-202-202feq;p;θT,whereθisthetimeassociatedtothenumberofrelativepositionqrelativepositionqrelativepositionqround-tripsinthering,andqandparethelongitudinal-101coordinateandelectronenergyvariables,(t,n)(ar