Far-Infrared Laser Diagnostics in EAST.pdfVIP

PlasmaScienceandTechnology，Vo1．13，No．3，Jun．2011 Far．Infrared LaserD iagnosticsin EAST SHINan(史楠)，GAOXiang(高翔)，JIEYinxian(揭银先)， ZHANGShoubiao(张寿彪)，ZENGLong(曾龙)，WANGErhui(王二辉)， YANGYao(杨耀)，LIUZixi(刘子奚) InstituteofPlasmaPhysics，ChineseAcademyofSciences，Hefei230031，China A bstractStructure．improvementsandexperimentresultsofaverticalthreechannelfar—in— frared(FIR)hydrogencyanide(HCN)laserinterferometer，operatedroutinelyinEASTtomeasure theelectrondensityprofile，arepresented．Moreover，afive—channeldeuteriumcyanidefDCN)laser interferometerwas developedsuccessfully．Somekeyissuesconfrontedindevelopment，including theeconomization ofworkinggasandthesolution to atmosphericabsorption areresolved and describedindetam Keywords：plasmaelectrondensity,FIR laserinterferometer，laserpowerstabilization， atmosphericabsorption PACS：52．55．Fa．52．70．Kz 1 Introduction 2 Three—channelHCN laser in— terferom eter FIR laserdiagnosticsarewidely usedontokamaks The optica1system ofthe HCN interferometeris to determine the distribution ofthe electron density in plasmaaswellasitstemporalevolution[ 引． The shown in Fig．1． It isa heterodynelaser interferom- line—averaged density in EAST lies in theregion of eterwith theMach．Zehnderarrangement．Thelaser 0．5×1019m一3to40x1019m一3 beam isdividedintoarefereneebeam andthreeprob— ． ． Theminorradiusof plasmaand thedistancefrom theequatorialplaneof ingbeamspassingverticallyatmajorra