G8-自由电子激光原理_黄志戎.ppt

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1、FELprinciple黄志戎(ZhirongHuang)自由电子激光原理1DtheoryLectureOutlineSASEandXFELFELR&D“Asolutionlookingforaproblem."3LightBulbvs.LaserA.Schawlow(Nobelprizeonlaserspectroscopy),ScientificAmericans,1968Radiationemittedfromlightbulbischaotic.Pinholecanbeusedtoobtainspati

2、alcoherence.Monochromatorcanbeusedtoobtaintemporalcoherence.PinholeandMonochromatorcanbecombinedforcoherence.Laserlightisspatiallyandtemporallycoherent.ProducedbyresonantinteractionofarelativisticelectronbeamwithEMradiationinanundulatorFreeElectronLaser(FEL)

3、electronbeamphotonbeame-beamdumpundulatorTunable,Powerful,CoherentradiationsourcesJohnMadey—InventoroftheFEL(1971)ThreeFELmodesFELoscillators(High-averagepower)SinglepassFELs(SASEorseeded)(SR)BrightlightsourcesfromrelativisticelectronsElectronsemitwithrandom

4、phaseradiationintensityN(gisLorentzfactor,Nisnumberofelectrons~109)SynchrotronradiationUndulatorradiationLinacCoherentLightSource(LCLS)atSLACInjectorExisting1/3Linac(1km)(withmodifications)NearExperimentHallFarExperimentHallUndulator(130m)X-FELbasedonlast1

5、-kmofexisting3-kmlinacNewe-TransferLine(340m)1.5-15Å(14-4.3GeV)X-rayTransportLine(200m)ProposedbyC.Pellegriniin1992EraofXFEL(2009)XFELsareExtremelyBrightandUltrafasttimeXFEL1012photonsSynchrotron106photons100fs10psNote:synchrotronsourcesaremuchhigherrep.rate

6、thanXFELsOrderedStructuresEquilibriumPhenomenaDisorderedStructuresNonequilibriumPhenomenaTransientStates19002000futureEraofCrystallineMatterEraofDisorderedMatterCoherentX-rayProbesConventionalX-rayProbesFutureRoleofFELsandAdvancedSourcesH.Dosch(DESY)Undulato

7、rradiationWorksforharmonicslh=l1/hUVSOR,Okazaki,Japanluforwarddirectionradiation(andharmonics)undulatorparameterK=0.94B[Tesla]lu[cm]Canenergybeexchangedbetweenelectronsandco-propagatingradiationpulse?l1LCLSundulatorK=3.5,lu=3cm,e-beamenergyfrom3GeVto15GeVtoc

8、over1=30Åto1.2ÅElectronandPhotonInteractionResonantinteractionenergy=(-0)/0phase=(k1+ku)z-1tradiationwavenumberundulatorwavenumberUsevariablesarrivaltimeatundulatordistanceFELlongitudinal