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1、2006researchreportof“ECRplasmacurrentstartupwithelectrodedischargeassistance”(researchcontractNo.12935/R0)RecentProgressonSUNIST1,2*HEYexi,*TANYi,*XIELifeng,*GAOZhe,*GUANXiaoyin,*LIUFei,*WANGWenhao,*XIEHuiqiao,*ZENGLong,*ZHANGLiang,**WANGLong,**YANGXuanzong,**FENGChunhua,**FUHong
2、jun11ThisworkissupportedbyInternationalAtomicEnergyAgency(ResearchcontractNo.12935/R0)2ThisworkissupportedbytheNationalNatureandScienceFundofChina(Grantnumbers:10275041and10375089)*SUNISTLaboratory,DepartmentofEngineeringPhysics,TsinghuaUniversity,Beijing100084,P.R.Cnina**SUNISTL
3、aboratory,InstituteofPhysics,ChineseAcademyofSciences,Beijing100080,P.R.ChinaIn2005-2006,themaincircuitofohmicfieldmagnethasbeenmodifiedandtested.Continuously,betterresultsfromElectronCyclotronwaveCurrentStartup(ECCS)experiment,longernon-inductiveplasmacurrent,havebeenobtainedtoo
4、.Byaddingaturn-offcircuittotheswitchoftheohmicfieldmaincircuit,threeSiliconControlledRectifiers(SCR)connectedinparallel,willbeturnedoff.Thenthecurrentincoilisdischargetofly-wheeldiodebranchwitha0.1Ohm,connectedinseries.TheohmicfielddecaysatasmallerL/Rtimeconstantof6msthan30msbefo
5、remodification.Thetestdischargeofmodifiedpowersupplyisassistedbya2.45GHz/1kWmicrowavepre-ionizationforlowerbreakdownloopvoltage.Resultsofthetestshowedthefurthermodificationisnecessaryforsuitablerampuprateofplasmacurrent.Inthepreliminaryexperiments,2.45GHz/60kWECWonSUNISTcanonlyst
6、artupaspikecurrentwithveryshorttimeduration(500A/0.3ms).Thelackofdensitycontrolwasoneofthereasonssupposedtoberesponsibleforthespikecurrentdriven.Thisyear,wehavetakenmosteffortstoreducebackgroundgaspressureandimprovewallcondition.First,aCRYO-PLEX8LPhighvacuumcryogenicpumpwasinstal
7、ledinSUNIST,loweringthebackgroundpressurefromgreaterthan1×10-4Pato5-8×10-5Pawhenoperatingwithdischarges.Second,thegaspuffingvalvewasmovedtothetopofthedevice,directtothevacuumchamberwithoutlong-slim-pipe,resultsinanotableshorteningofpuffingpulsefrom8msto2msandgas-fillinglatencyfro
8、m30msto3ms.Third,thechamberwallwassilico
