LAPECR2离子源在320kV高压平台上的试运行

131òOr.pUÔn†ØÔnVol.31,Supp..2007c7HIGHENERGYPHYSICSANDNUCLEARPHYSICSJul.,2007CommissioningTestofLAPECR2Sourceonthe320kVHVPlatform*1)SUNLiang-TingLIJin-YuZHANGXue-ZhenWANGHuiMABao-HuaLIXi-XiaFENGYu-ChengSONGMing-TaoZHUYu-HuaZHAOLi-MinWANGPing-ZhiLIUHui-PingZHAOHong-WeiMAXin-WenZHANWen-Long(InstituteofModernPhysics(IMP),ChineseAcademyofSciences,Lanzhou730000,China)AbstractThehighchargestateallpermanentElectronCyclotronResonanceIonSource(ECRIS)LAPECR2(LanzhouAllPermanentmagnetECRionsourceNo.2)hasbeensuccessfullyputonthe320kVHVplatformatIMPandalsohasbeenconnectedwiththesuccessiveLEBTsystem.ThissourceisthelargestandheaviestallpermanentmagnetECRISintheworld.Themaximummirroreldis1.28T(withoutironplug)andtheeectiveplasmachambervolumeisaslargeas67mm255mm.Itwasdesignedtobeoperatedat14.5GHzandaimedtoproducemediumchargestateandhighchargestategaseousandalsometallicionbeams.Thesourcehasalreadysuccessfullydeliveredsomeintensegaseousionbeamstosuccessiveexperimentalterminals.ThispaperwillgiveabriefoverviewofthebasicfeaturesofthispermanentmagnetECRIS.Thencommissioningresultsofthissourceontheplatform,thedesignoftheextractionsystemtogetherwiththesuccessiveLEBTsystemwillbepresented.KeywordsECR,highcharge,beamtransmission1Introductionheavyionformanyyears.TheHIRFLlowenergyECRionsourceplatformandtheHIRFLaccelerators[1]WiththeprominentdevelopmentofElectronCy-togetherwiththelatest-builtHIRFL-CSR(CoolerclotronResonance(ECR)ionsourceinthelasttwoStorageRings)willprovidethephysicsresearchesiondecades,ithasbecomethemostecientandin-beamscoveringalargeenergyrange.AndtofurtherdispensablemachinetoproduceintensehighchargeextendthepresentenergyrangeavailableinInstitutestateionbeams.ECRionsourcealsoprovesitsob-ofModernPhysics(IMP),a320kVhighvoltage(HV)viousimportanceintheeldssuchasacceleratorde-platformhasbeenrecentlybuilt.Amultiplechargevelopment,atomicresearch,materialphysicsandbi-allpermanentmagneticECRionsourceLAPECR2ologytechniquesetc.Andtheavailabilityoflowen-hasbeendesigned,builtandinstalledontheplatformergy,intense,highchargestate,highdutyfactoriontoproduceintensemultiplechargestateionbeamsforbeamsfromECRionsourcehasopenedmanyareasthesuccessive5experimentalterminals.ThegoalofofMCIresearchthatpreviouslyinaccessible.HeavythissourceistoreachthebeamintensitiesequivalentIonResearchFacilityinLanzhou(HIRFL)hasbeentothoseofLECR2source.Thissourcewassuccess-dedicatedtotheresearchactivitiesassociatedwithfullybuiltandgavetherstplasmain2005.InthisReceived20April2007*SupportedbyPilotProjectofKnowledgeInnovationProgram(KJCX1-09)andNationalNaturalScienceFoundationofChinaforYoungScientists(10305016)1)E-mail:sunlt@impcas.ac.cn55|59 56pUÔn†ØÔn(HEP&NP)131òpaper,thegeneralcommissioningresultsofthistheinjectionsideandextractionsiderespectively.sourceontheplatformarepresented.3Magneticeld2ConceptualdesignThemagnetbodywassuccessfullybuiltinIMP.Accordingtothecarefulmeasurementofthemag-LECR2sourceisoneoftherstECRionsourcesneticeld,themagneticeldcongurationisclosethatadoptedthetechniquessuchashighfrequency,toourdesign.Fig.1givesthecomparisonofthede-high-Bmodeandlargeplasmachamber.Thenalsignedandmeasuredaxialmagneticeldcongura-performancesofthissourcewerecomparablyhighattions.Theinjectionmagneticeldpeakis1.28Tthatthattime.Toproducetheequivalentperformanceofistoolowfortheoptimumoperationat14.5GHz.ButLECR2,themainparametersofLAPECR2shouldbeanironpluginsertionattheinjectionsidemayhelpdesignedclosetothoseofLECR2.Withthedevelop-increasethemagneticeld.TheBmin=0.42T,Bext=mentofpermanentmagnetmaterialtechniques,itis1.07TandBrad=1.2Tresultsarewelluptotheopti-nowadayspossibletodesignandfabricateanallper-mummagneticeldrequirementsofa14.5GHzECRmanentmagnetbodytoproduceveryhighmagneticionsource.AndthetypicalparametersofLAPECR2eld.LAPECR2sourcewasdesignedtobeoperated[5]sourceareclosetothoseofLECR2source.at14.5GHzwithseveralkeyaspectsbeingtakenun-derconsiderationatthesametime,forinstance:i.plasmachambershouldbeaslargeaspossibletofeedrfpowerandtorealizebetterionconnement;ii.largeresonancezoneisfavored;iii.compromisebetweenthemagneticeldandthemagneticbodycompactness.Thesuccessfuldesignandfabricationofseveralall[2,3]permanentmagnetECRionsourceshavegivensomereferencestothedesignofLAPECR2source.Furthermore,thelatestupdatedempiricalscalingFig.1.Measuredandcalculatedresultsofthe[4]lawscanbecountedasabasictheoryinthedesign.magneticeldofLAPECR2.Intheotherhand,themagneticeldofanallper-manentmagnetionsourceisunchangeable,whichis4Preliminarycommissioninganintrinsicdrawbackofthiskindofsource.Reason-abledesignofthemagneticeldcongurationoftheAfterthemagneticmeasurementofLAPECR2sourcewillmakethesourcemorepowerful.source,itwasremovedtoanotherbuilding.Then14.5GHzrfpowerisdirectlyfedintothe67mmthemagnetbodywassuccessfullymountedonthediametercopperplasmachamberwithalineralu-HVplatform.Theinstallationoftheaccessorypartsminumlmcylinderinside.WR62 angewaveguidestothesourcewascompletedatthebeginningof2005.areusedforrfpowerfeeding.Thedoublewallwa-Afterseveraltestsofhighvoltageinsulationandvac-tercoolingstructureisadoptedinthedesignoftheuumpumpingofthesource,theionsourcewasig-plasmachamber.OneinsertionportisalsoavailablenitedinJuly2005at14.5GHz.Someionbeamswereontheinjectiontankformacro-ovenorinsertedrodextractedbythe15kVHVandanalyzedbytheana-6+toproducemetallicionbeams.Typicaltrickslikelyzingmagnet.60eAObeamwasobtainedwith[5]mixinggasandbiaseddiskareappliedtothesourcetherstplasma.design.Vacuumevacuationofthechamberisreal-Becauseoftheopticaldesignoftheiontransmis-izedbya110l/sanda360l/smolecularpumpatsionbeamline,thedistancebetweentheplasmaelec- Or.šû˵LAPECR2lf 3320kVpزþÁ$157trodeandthesolenoidalcoilisverysmall,andthecientcooling.Thenasamedimensionstainlesssteelthusthedimensionoftheextractiontankisquitelim-plasmachamberwasinstalled.Withabout450W6+ited.Ontheotherhand,themolecularpumpshouldrfpowerinjectionmorethan0.5emAObeamwasbeputasfaraspossiblefromthemagnetbodyandobtainedwiththetotaldraincurrentabout6emA.thesourcesymmetricaxistoavoidthepossibledam-BecauseofsummermaintenanceatIMP,thesourceageofthestraymagneticeldofthesourcetothehadtobestopped.Beforethat,atwo-hourtuningpump.Thus,theeectivevacuumevacuationspeedofargonionbeamgavesomepreliminaryresultsof8+ofthepumpattheextractionsideisquitelow.Theseargonionbeams.Morethan300eAArwasob-aspectslimitthesourcevacuum.ThenormalbasetainedinthetestandFig.2presentsthespectrum611+vacuumofthesourceisabout1.210mbaratthewhenoptimizingtheproductionofArbeam.Ob-7injectionsideand9.010mbarattheextractionviousnitrogenandcarbonionbeampeaksareseeninside.thespectraillustratedbyFig.2,whichdenotessomeTheionbeamextractionfromanallpermanentvacuumleakageandoutgassingareinexistence.Ta-magnetECRionsourceismorecomplexthanaclas-ble1givesthepreliminaryresultsofLAPECR2insicalECRionsource.Becauseofthemagneticstruc-comparisonwiththoseofLECR2.Badvacuum,out-tureofthesource,theextractionregionofanallper-gassingandlowionbeamtransmissioneciencymaymanentmagnetECRionsourceisquitelong,espe-accountforthelowerperformanceofLAPECR2thanciallyforthecaseofLAPECR2source.TodecreaseLECR2.thestrongin uenceoftheextractionmagneticeld,thepullerelectrodeofLAPECR2isputascloseaspossibletotheplasmaelectrode.Inthiswaytheionbeamextractionelectriceldisincreasedandtheionbeamaccelerationdistance(verylowenergytrans-missiondistance)isdecreased.Butbecauseoftheextractedionbeambombardmentonthepullerelec-trode,thevacuumconditionattheextractionregion6becomesworse,normally2.010mbarattheex-tractionside.Thepoorvacuumandthestrongmag-Fig.2.ArgonCSDforoptimizingAr11+production.neticeldattheextractionregionmakeitdiculttoTable1.Comparisonofthepreliminaryre-increasetheextractionHVhigherthan22kVbecausesultsofLAPECR2withtheperformancesofofthePenningdischarge.Andthen20kVextractionLECR2(eA).HVisnormallyappliedduringthetest.IonLAPECR2LECR2BecausetheavailableTWTrfpowergeneratoratO6+550610handcanonlyprovidethemaximumoutputrfpowerO7+130140Ar8+310460of280W,a14.5GHzklystronrfpowergeneratorwithAr9+200themaximumrfpoweroutputof450WwasconnectedAr11+105185withtheionsourcethoughaHVDC-break.TotestAr12+53105Ar13+19thesuccessivebeamlinesoftheHVplatform,theAr14+612analyzedionbeamswerelettotheexperimentalter-minalsduringthecommissioning.Inthepreliminary5Beamextractionandtransporttests,onlyoxygenbeamsweretunedfortheplat-formtest.Accordingtothetest,intenseoxygenionIonbeamextractionsystemisveryimportantforbeamsweresuccessivelyextractedfromthesource.anionsource.Higheciency,goodqualityionbeamButunfortunately,thealuminumlmcylinderlinerextractioninquiresanoptimumionbeamextractioninsidetheplasmachamberwasburntbecauseofinsuf- 58pUÔn†ØÔn(HEP&NP)131òsystem.ForclassicalsolenoidalcoiltypeECRionandthentheionbeamsdefocusesalittlebit,andsource,theextractedionbeamsexperienceasemi-afterthattheionbeamstransmitacertaindistanceGlaserlensmagneticeld,whichdecaysveryfasttoinaquasi-parallelmode.Certainly,thespacecharge0alongthesymmetricaxis.Thusthein uenceofeectplaysanimportantrolewhichmakestheionthestraymagneticeldtotheextractedionbeamsbeamsdivergesbysomedegreebeforetheentranceisnotverysevere.Butastothecaseofallperma-oftheanalyzingmagnet.ItispredicablethatthenentmagnetECRionsource,thein uenceofthespecialextractionmagneticeldcongurationofanstrayeldtotheextractedionbeamsisquitesevere.allpermanentECRionsourcehasstrongin uenceFig.3presentsthemagneticeldcongurationatontheextractedionbeamtransmissionoptics.theextractionsideofLAPECR2source.Theextrac-tionmagneticelddecreasesto0afteracertaindis-tanceandthenanegativemagneticeldpeakarises.Thenthenegativemagneticeldslowlydecreasesto0afteraverylongdistance.Thisspecialmagneticeldcongurationhasasevereimpactontheex-tractedionbeamtransmission,especiallyforthecaseFig.4.PBGUNSsimulationresultsoftwoofLAPECR2source(theextractionmagneticeldiskindsofmagneticeldcongurationin u-strongerthantheotherpermanentsources).ences.TheenergyrangeofIMPHVplatformis20|320kV/q.Torealizethehigheciencytransportoftheextractedionbeamfromthesourcetoeachoftheexperimentalterminals,optimumdesignoftheionbeamtransmissionopticalsystemisveryimpor-tant.Inourprincipledesign(asshowninFig.5),ionbeamsextractedfromLAPECR2transmittoa120
mm
mradacceptance90analyzingmagnetwiththeentrancedimensionof70mm68mm.ThentheanalyzedionbeamfocusesbeforetheFaradayFig.3.Extractionsidemagneticeldconguration.cup.ThepositionoftheionbeamextractionholeFigure4illustratesthesimulationoftheionbeamandthepositionofthefaradaycupformasimpleextractionandtransmissionfromLAPECR2sourcepointtopointopticalimagesystem.AGlaserlens[6]withPBGUNScode.Intheupperplot,ionbeamisaddedforslightadjustmentoftheionbeamtrans-extractionfromaclassicalsourcewithanormalex-mission.Fig.7presentssomesimulationresultswithtractionmagneticeldcongurationissimulated.ItTrace3Dcode.Theupperplotillustratestheex-denotesthattheaftertheionbeamsbeingextracted,tractedionbeamtransmissionsituationforaclassicaltheextractedionbeamsrstlyfocusnearthepullersourcewithanormalextractionmagneticeldcong-andthengraduallydefocustilltheentranceoftheuration.Thelowerplotpresentsthesimulationresultanalyzingmagnet.AlthoughaGlaserlenshasbeenoftheextractedionbeamfromLAPECR2.Easytoaddedtohelpfocusthebeam,mostoftheunwantedseethatunliketheconventionalECRionsources,theionbeamsandpartofthetunedionbeamwillbeionbeamextractedfromanallpermanentECRionlostduringthetransmission.ThelowerplotgivessourcecannotformagoodfocuspointattheFara-thesimulationresultoftheionbeamextractionanddaycup,andonlyafatlargeenvelopebeamwaisttransportfromLAPECR2.Itillustratesthattheex-canbedetected.Thisresultisfardierentfromthetractedionbeamswillformafocusnearthepulleroriginaldesignoftheionbeamtransmissionoptical Or.šû˵LAPECR2lf 3320kVpزþÁ$159system.Andthatiswhytheeectofthesuccessiveseveralreasonsmightresultinit,forinstancethebadEinzellensisveryweak.extractionvacuum,thelowextractionhighvoltage,thesmallacceptanceoftheanalyzingmagnetandthebeamlinemisalignmentproblem.Fig.5.BeamenvelopsfromLAPECR2sourcewhentheplatformisgrounded(20qkeVbeam).6+AccordingtothepreliminarytestwithO,theestimatedtransmissioneciencybetweenthesourceFig.6.Trance3DsimulationresultsoftwoandtherstFaradaycupisaboutlessthan40%.kindsofmagneticeldcongurationin u-ThetransmissioneciencybetweentherstFaradayences.cupandthesecondFaradaycupbehindtheaccelera-tioncolumnismorethan80%whentheHVplatform6Conclusionisgrounded,butthetransmissioneciencybetweentherstFaradaycupandtheFaradaycupattheex-TheallpermanentmagnetLAPECR2sourceatperimentalterminalisonlyabout30%|35%.ItIMPhasproducedsomepreliminaryresultsonthe6+meansthatthesuccessiveionbeamtransmissionsuf-320kVHVplatform.Typicalbeamslike550eAO,7+11+14+fersalotfromtheopticalmismatchingofionbeam130eAO,105eAArand6eAArhavetransmissionbetweentheplatformandthesuccessivebeenextracted.Theanalyzedionbeamwastunedbeamline.HigherextractionHVandapplyingthetooneoftheexperimentalterminal.Althoughthe6+HVplatformwithHVmayhelpincreasethetrans-poortransmissioneciency,morethan80eAOmissioneciency.Screeningofthenegativemagnetichavebeendetectedattheterminalwhentheplat-eldwithanironblockattheextractionsideisan-formisgrounded.Neststepworkwillfocusontheothergoodsolution.Asforthelowtransmissione-enhancementofthetransmissioneciencyandtheciencybetweenthesourceandtherstfaradaycup,improvementofthesourcevacuum.References2005),No.0{7354{0234{5/05,123|1264HitzDetal.Rev.Sci.Instrum.,2002,73:5091XIAJia-Wenetal.Nucl.Instr.andMeth.Phys.Res.,2002,5SUNLTetal.Rev.Sci.Instrum.,2006,77:03A319A488:116BoersJE.ADigitalComputerCodefortheSimulation2XieD.Rev.Sci.Instrum.,2002,73:531|533ofElectronandIonBeamsonAPC,IEEECat.No.3HitzDetal.Proceedingsofthe16thInternationalWork-93CH3334-0(1993)213shoponECRIonSources,Berkeley,CA(AIP,NewYork,