高增益自由电子激光光阴极注入器驱动激光系统设计考虑

366Vol.36,No.6200211AtomicEnergyScienceandTechnologyNov.2002,,,,,,,(,100871):,260nm68ps500JNdYAGQ,110ps:;;:TN243;TN24816:A:100026931(2002)0620527204StudyontheDriveLaserSystemofthePhotocathode2injectorUsedinHighGainFELLUXiang2yang,XIANGRong,ZHAOKui,WANGLi2fang,QUANSheng2wen,HAOJian2kui,ZHANGBao2cheng,CHENJia2er(InstituteofHeavyIonPhysics,PekingUniversity,Beijing100871,China)Abstract:HighgainFELrequireshighqualityelectronbeamwhichcanbeprovidedonlybytheRFphotocathodegun.Thedrivelaserforelectronsourceplaysthekeyrole.InInstituteofHeavyIonPhysicsofPekingUniversity,thelasersystemisrequiredtodelivera500J,68pspulseofUVphotons(260nm)tothecathode.ThissystemmainlyconsistsofaCW,frequency2doubled,diode2pumpedNdYAGlaser,whichprovidesenergytopumpaCWmode2lockedTisapphireoscillator,Q2switchedNdYAGpumplasers,aregenerativeamplifierandharmonicscrystals.Tomeetthelowjittersofpulses(1.0ps),cavitylengthoftheoscillatorshouldbeadjustabletolockthepulsefrequencywithexternalRFreference,andaphasestabilityfeedbacksystemisalsoused.Keywords:photocathodeRFelectrongun;drivelaser;highgainfreeelectronlaser:2001206206;:2001208228:(19735004):(1963),,,,:,,,,,,,,,,,1[1,2]:,,,13GHz,:,1%;,1ps;,1%;,1%;,1%;,5%/8h,,,[2,3],:,,,,[2]21,:,260280nm;,500J;,50Hz;,1ps;,8ps;,1%;,;,;,1%;,1%1Fig.1SchematicdiagramofthedrivelasersystemforthephotocathodeRFelectrongun,,211:,NdYAGNdYLFTiSapphire[4]TiSapphire,[2]:800nm,260280nm382536,,;100fs,;;TiSapphire,,,CWNdYAGTiSapphire82MHz,8116MHz(2856MHz35)81125MHz(113GHz16):780nm;8082MHz;80fs;10nJ;212,260nm50Hz68ps500J,:1);2);3);4),,,,,(2),(10nJ),1nJ,50%,780nm260nm15%20%,,,5%15%,50%,1525mJ,11nJ780nm1525mJ50Hz1%,,,,2Fig.2Sketchofthechirpedpulseamplificationtechnique,,3[5],,,,,3Fig.3Principlediagramofspatialfilterusedforlongitudinalprofileadjustment9256:,20mJ,100mJ(532nm)(QYAG),,50Hz,,,,,,,,,2134,,:,PTZ,,,,50Hz,(picomotor),214,,BBO780nm3,34Fig.4Thebasicsystemsetupoftimingcontrol,,,CWTiSapphire,,,,500J50Hz,,:[1]YeremianD.RequirementsforRFGuns[A].Pro2ceedingsoftheLaserforRFGunsWorkshop[C].US:NationalTechnicalInformationService,DepartmentofCommerce,1994.123124.[2]TheLCLSDesignStudyGroup.LinacCoherentLightSource(LCLS)DesignStudyReport:Stanford,CA,94305[R].USA:StanfordUniversity,1998.[3]AlleyR,BharadwajV,ClendeninJ,etal.TheDe2signfortheLCLSRFPhotoinjector[J].NuclIn2strumMethodsPhysRes,1999,A429:324331.[4]JohnD.CapabilitiesofLasers,PresentandFuture[A].ProceedingsoftheLaserforRFGunsWork2shop[C].US:NationalTechnicalInformationSer2vice,DepartmentofCommerce,1994.2339.[5]WeinerA,LeairdD,PatelJ,etal.ProgrammableFemtosecondPulseShapingbyUseofaMultiele2mentLiquid2crystalPhaseModulator[J].OpticsLetters,1990,15(6):326328.03536