High Brightness Negative Ion Sources with High Emission.ppt

highcurrentdensityandhighbrightnessh-sourcesforaccelerators,vadimdudnikovbrookhaventechnologygroup,inc.,fnal,december2005,acknowledgments,iamverygratefultotheisisteamforchoosingchargeexchangeinjectionandpenningspsforisisoperationandforsuccessfuldemonstrationofitshighperformanceinrealacceleratoroperation.,penningspsintheisisrfq,abstract,operationexperienceofcompactsurface-plasmasources(csps)underoperationindifferentlaboratoriesaroundtheworld,willbeconsidered.featuresofcspsaresmallvolume,smallgapsbetweenelectrodes,highplasmadensityandhighemissioncurrentdensityandhighbrightness,highpulsedgasefficiencyandlowelectroncurrent.inmanyversionsofcspswerereachedverylongoperationtime.featuresofcspsimportantforlongtimeoperationwillbeconsidered.,contents,introduction.historicalremarks.negativeionproductioninsurface-plasmainteraction.cesiumcatalysis.surfaceplasmasources-sps.charge-exchangecooling.electronsuppression.beamextraction,formation,transportation.spacechargeneutralization.instabilitydamping.spsdesign.gaspulser,cesiumcontrol,cooling.spslifetime.spsinaccelerators.furtherdevelopment.summary.acknowledgment.,horstklein(20icfaworkshopsummary).,“theionsources,andespeciallytheh-sources,arestillsomewhatablackmagic.thereforeintensetheoreticalandexperimentalworkhastobeperformedindifferentlabstoachievethenewrequirements.ineuropethenegativeionsourcenetwork,supportedbytheeuropeanunion,withits8partnerswillhelptoreachthegoal.butalsosuchameetingaswehavehadinfemilabisveryhelpfulandintensifiestheworldwidecollaboration.concerningthedifferenttypesofionsources,ithinkthemostpromisingcandidatesforh-arethepenningionsourceandthevolumesource(largevolumesps).theecrsourcemaybeahopeforthefuture”.intuitionandhandexperienceareimportantcomponentsforh-sourcesdevelopment.,h-beambrightnessindifferentsps(r.welton,sns).,beambrightnessandpulsecurrentofoperationalionsources(points)andnewfacilityrequirements(rectangles)magnetronsources:1-desy,2-bnl,3-anl,4-fnal.multicusprfsources:5-desy,6-ssc;penningsources:7-raland8-inr;.multicuspsurfaceconversionsources:9-kekand10lanlmulticuspfilamentsources:11-triumfand12-jyvaskyla.,ionsourcerequirementsfornewacceleratorsprojects(fromr.scrivensreview),ionsourceparametersrequiredforselectedhighpowerproject.1rms,normalized,inmmmrad,huashungzhang,ionsources,springer,1999.p.326,basedontheachievementsofpositiveionsources,h-ionsourceshavebeendevelopedintwoways:1)negativeionsareextractedfromtheplasmaofpositiveionsources.beforethe1970s,theh-currentwaslimitedtolessthan5ma.thisisbecauseinageneralhightemperatureplasma(te10ev)theh-formationcrosssection(10-18cm2)is3to4orderslessthantheh-destructioncrosssections(2to7x10-14cm2).in1962,krohn7discoveredthattheyieldofsputterednegativeionsincreasedbyoneorderwhilecs+ionsimpactedthemetaltarget.unfortunately,thisresultwasnotimmediatelyusedtodevelopanisupto1970.anh-surfaceplasmasource(sps)wasinventedbyintroducingcesiumintothehydrogendischargeplasmaat1971.itquicklyledtoincreasingtheh-currenttoseveralamperes.alsothecesiumsputternisswererapidlydeveloped.sincediscovering,attheendofthe1970s,thatthedissociativeattachmentcrosssectionofhighlyvibrationallyexcitedh2-moleculesinalow-temperatureplasmaishigherby104-105thanthegroundstate8,9,high-intensityvolumeh-ionsourceshavebeendeveloped.attheendofthe1980s,h-volumeionsourcescombinedwithcesiumhasevolvedwithdominationofsurface-plasmagenerationofnegativeions.,adsorptionofalkalinemetalssignificantlyincreasesthesecondaryemissionofnegativeions,in1961,byahmetayukhanov(tashkentelectronicsinstitute)wasobservedthattheadsorptionofalkalinemetalssignificantlyincreasesthesecondaryemissionofnegativeions.alittlelatertheinvestigationsofthiseffectwerepresentedbykrohn(argonnenat.lab.).however,evenwiththepresenceofcesiumonthesurfacetheintensityofbeamsofnegativeionsobtainedbythesecondaryemissiondidnotexceedthemicroamperelevel.theseresultsbecamethebasisofsecondary-emissionsputteringnegativeionsourceswithamicroamperelevelintensityfortandemaccelerators.a.ayukhanov,phd.thesis,secondaryemissionofnegativeionswithbombardmentbyalkalipositiveions.1961.u.a.arifov,anda.kh.ayukhanov,izvestiyaanuzbek.ssr,ser.fiz.mat.nauk.no.6,34(1961).inbooku.a.arifov,interactionsofatomicparticleswithasolid(nauka,moscow,1986).v.e.krohn,j.appl.phys.33,3523(1962).,budkerinstituteofnuclearphysicswww.inp.nsk.su,historyofsurfaceplasmasourcesdevelopment,(j.peters,rsi,v.71,2000),cesiumcatalysis:“enhancementofnegativeionproductionbyadmixtureintodischargeasubstancewithalowionizationpotential,suchascesium”.,intensityofnegativeionbeams:1971-discoveryofcesiumcatalysis.,h-/d-lvspsfortokomacneutralbeaminjectors$0a,1mev,1000s,1billion$,historyofchargeexchangeinjection(rees,isis,icfaworkshop),1.1951alvarez,lbl(h-);1956moon,birminghamun.(h+2)2.1962-66budker,dimov,dudnikov,novosibirsk;firstachievements;discoveryofe-pinstability.ipm3.1968-70ronmartin,anl;50mevinjectionatzgs4.1972jimsimpson,anl;50-200mev,30hzbooster5.1975-76ronmartinetal,anl;61012ppp6.1977rauchasetal,anl;ipns50-500mev,30hz7.1978hojvatetal,fnal;0.2-8gev,15hzbooster8.1982bartonetal,bnl;0.2-29gev,ags9.1984firstveryhighintensityrings;psrandisis10.1980,85,88ihep,kekbooster,desyiii(hera)11.1985-90ehf,ahfandkaondesignstudies.ssc12.1992ags1.2gevboosterinjector13.1990sess,jhfandsns4-5mwsources,inpnovosibirsk,1965,bunchedbeam,firstobservationofane-driveninstability?coherentbetatronoscillationsthreshold1-1.5x1010,circumference2.5m,stabilizedbyfeedback(g.budker,g.dimov,v.dudnikov,1965).f.zimmermann,otherinppsr1967:coastingbeaminstabilitysuppressedbyincreasingbeamcurrent;fastaccumulationofsecondaryplasmaisessentialforstabilization;1.8x1012in6m,v.dudnikov,pac2001,pac2005,cspatentv.dudnikov,themethodfornegativeionproduction,suauthorcertificate,c1.h013/04,no.411542,applicationfiledat10march,1972,granted21sept,1973,publishedbul.no2,15jan.1974.,“enhancementofnegativeionproductionbyadmixtureintodischargeasubstancewithalowionizationpotential,suchascesium”.,spswasdevelopedincooperationofbdd,g.dimov,v.dudnikov,andyu.belchenko,spsforacceleratorswasdevelopedincooperationwithg.derevyankin,historyofvolumesourcesdevelopment,(j.peters,rsi,v.71,2000),blueframeisseparatesurfaceplasmadominatedh-formationdevelopmentofvolumesourcesisfinishedbyconversionintolargevolumesps.,marthebacalfourthiaeatechnicalmeetingon“negativeionbasedneutralbeaminjectors”9may2005,“whationsourceforvolumeproduction?newionsourceswereproposedformakinguseofthevolumeproductionmechanism.themagneticmultipole,usedin1976inourfirstexperiments(nicolopoulouetal,j.phys.1977)wasmodifiedbytheadditionofamagneticfilter.thisseemedtosolvetheproblemofh-destructionbyfastelectrons,sincetheywereeliminatedfromtheextractionchamber.however,thissolutionwasonlypartial,fortworeasons:*thenegativeionsmaynotbeformedintheextractionchamber,butinthedriver,nearthefilaments;*themagneticmultipoleisveryefficienttodissociatemolecules,buthatomsdestroyh-andh2(v)!whencesiumwasintroducedinthemagneticallyfilteredmultipole,itappearedasasuitablesourceforproducingatomsandpositiveionsforsurfaceproduction.obviously,thisdeviceisnotsuitableforvolumeproduction!itisreallyagoodlargevolumesurfaceplasmasource,notavolumesource.”,generaldiagramofthesurface-plasmamechanismforproductionofnegativeionsinagasdischarge,surfaceplasmagenerationofh-onanodeoftenisadominantprocessofh-formationindischargeswithoutcs,aswellwithcs,(a)planotron(magnetron)flatcathode(b)planotrongeometricalfocusing(cylindricalandspherical)(c)penningdischargesps(dudnikovtypesps)(d)semiplanotron(e)hollowcathodedischargespswithindependentemitter(f)largevolumespswithfilamentdischargeandbasedemitter(g)largevolumespswithanodenegativeionproduction(h)largevolumespswithrfplasmaproductionandemitter,1-anode6-hollowcathode2-coldcathodeemitter7-filaments3-extractorwith8-multicuspmagneticmagneticsystemwall4-ionbeam9-rfcoil5-biasedemitter10-magneticfilter,schematicdiagramsofsurfaceplasmasources,probabilityofh-emissionasfunctionofworkfunction(cesiumcoverage),schematicofnegativeionformationonthesurfacemichailkishinevsky,sov.phys.tech.phys,45(1975),coefficientofnegativeionizationasfunctionofworkfunctionandparticlespeed,enhancingsurfaceionizationandbeamformationinvolume-typeh-ionsourcesr.f.welton,m.p.stockli,m.forrette,c.williams,r.keller,r.w.thomae,epac2002,paris.,“cleary,onceagaincsmustresideonthesurfaceforthevastmajorityofitslifetimeinthesourceandthereforesurfaceionizationmustaccountfortheobservedenhancementofh-yield.inthesecases,thetermvolumeionsourceismisleadingsince,mostoftheh-resultsfromsurface,ratherthanvolumeionizationprocesses.therefore,ionsourcedesign,carefulconsiderationshouldbegrantedtheinteriorsurfacesofthesource”.correctclassificationofionsourcesisimportant,becauseitshoulddetermineadirectionofdevicesoptimization:tooptimizeavolumeproduction,orsurface-plasmaproduction.incorrectspeculationofmainmechanismofnegativeiongenerationwasreasonoflongtimedelayinimprovingofbeamparameters.,firstversionofplanotron(plainmagnetron)sps,inp,1972,beamcurrentupto230ma,1.5x10mm2,j=1.5a/cm2withcs,h-energyspectrafromplanotron,theionspectrafromaplanotronusuallyhavetwopeaksseparatedbyavalley.thelocationofthefirstpeakcoincideswiththeenergyeueximpartedtothenegativeionsbytheextractionvoltage.theionenergyofthesecondpeakishigherthanthatofthefirstpeakbyanamountclosetoeud.theoscillogramsintheupperpartofillustratethechangeinthespectra,asaresultofincreasingthedischargevoltageudfrom120v(l)to210v(4)byreducingthecesiumsupply.theoscillograms(1-4)inthelowerpartoffigureillustratedhowthespectravaryasaresultofincreasingthehydrogensupplytothedischargechamber,crosssectionsofplanotron(magnetron)spsofsecondgeneration:3.7a/cm2withcs(0.75a/cm2withoutcs),h-currentdensityfromplanotronwithcs(3.7a/cm2)andwithoutcs(0.75a/cm2),inp,novosibirsk,1972,schematicofsemiplanotronsps,1-emissionaperture;2-anode;3-cathode;4-cathodeinsulator;5-dischargechannal;6-extractor;7-magnetwithmagneticinsertions.,beamcurrentvsanarccurrentfordifferentslitgeometryinthesemiplanotron,dependencesofthe-ionbeamcurrentonthedischargecurrenthavethen-shapedformwiththreesections:lineargrowthatsmalldischargecurrents,saturationorafallingsectionatmediumcurrents,andlinear,butslowgrowthatthehighcurrents.,crosssectionthroughlanlversionofspswithpenningdischarge.,beamletimagesatpepper-potscinti1lator(noiselessdischarge).emissionslit0.5x10mm2.vertical:yplanehorizontal:xplane,schematicofisisversionofpenningdischargesps,cathodeandplasmaplateofisispenningspsafterlongtimeoperation,h-energyspectrafrompenningsps,reviewofscientifiinstruments,march2002,volume73,issue3,pp.1157-1160investigationofthemechanismofcurrentdensityincreaseinvolumesourcesofhydrogennegativeionsatcesiumadding,v.p.goretsky,a.v.ryabtsev,i.a.soloshenko,a.f.tarasenko,a.i.shchedrininstituteofphysicsofnationalacademyofsciencesofukraine,46prospectnauki,kiev03650,ukraineinthepresentarticletheinfluenceofaddingcesiumintothevolumeandonthesurfaceofanionsourceonitsemissioncharacteristicsisstudiedboththeoreticallyandexperimentally.itisshownthatcesiuminthevolumeatconditionsofarealionsourcebringsinasignificantcontributiontokineticprocesses,butweaklyinfluencesthecurrentofhionsextractedfromthesource.itisshownboththeoreticallyandexperimentallythatanobservedincreaseofthecurrentofhionswithcesiumaddedisduetotheconversionoffastparticlesattheanodesurface.thus,onthebasisofexperimentalresultsandcalculationsitcanbestatedthatcesiuminavolumeofthesourceunderstudycannotleadtotheincreaseofcurrenth-ions.observedgrowthofthiscurrentwithcesiumintroductionisduetoconversionofhydrogenatomatdischargeanodesurface,coveredbycesium.inotherwords,cesiumaddingresultsinthetransformationofthesourceofh-ionsofvolumetypetothesourceofsurface-plasmatype.yu.belchenko,g.dimov,v.dudnikov,nucl.fusion,14,113(1974),operationofdudnikovtypepenningsourcewithlab6cathodesk.n.leung,g.j.devries,k.w.ehlers,l.t.jackson,j.w.stearns,andm.d.williams(lbl)m.g.mcharg,d.p.ball,andw.t.lewis(afwl)p.w.allison(laml),thedudnikovtypepenningsourcehasbeenoperatedsuccessfullywithlowworkfunctionlab6cathodesinacesium-freedischarge.itisfoundthattheextractedhcurrentdensityiscomparabletothatofthecesium-modeoperationandhcurrentdensityof350ma/cm2havebeenobtainedforanarccurrentof55a.dischargecurrentashighas100ahasalsobeenachievedforshortpulsedurations.thehyieldiscloselyrelatedtothesourcegeometryandtheappliedmagneticfield.experimentalresultsdemonstratethatthemajorityofthehionsextractedareformedbyvolumeprocessesinthistypeofsourceoperation.reviewofscientificinstruments-february1987-volume58,issue2,pp.235-239,h-detachmentbycollisionswithvariousparticlesandresonancecharge-exchangecooling,resonancecharge-exchangecooling,cesiumescapingfromapulseddischargeinsps,thereisastrongsuppressionofthegasandcesiumflowfromtheemissionslitbythehighdensityplasmaofthedischarge.,gastrappingbydischargeincsps,qo-gasfluxwithoutdischargeqp-gasfluxwithdischargeid-dischargecurrent,h-beamintensityofsps,beamintensityvsdischargecurrentforfirstversionofsemiplanotron1976,evolutionofh-beamintensityinisis,years,emissionslit,emittance,normalizedemittance,normalizedbrightness,halfspreadsofenergyofthetransversemotionofions,reducedtotheplasmaemissionslit,characteristicsofqualityofthebeamformation:,emittance,brightness,iontemperature,l,x,y,x,dischargestabilityandnoise,diagramofdischargestabilityincoordinatesofmagneticfieldbandgasdensityn,theeffectivetransverseelectronmobilityvseffectivescatteringfrequencyandcyclotronfrequency,b,kg,n,1016cm-3,noisy,noiseless,n*,bmin,nodischarge,/,noiseless,=e/m(2+2),noiseofdischargevoltage,dependenceofdischargenoiseofmagneticfield,non2,qn2=0.46sccm,dischargenoisesuppressionbyadmixtureofnitrogen,p.allison,v.smith,et.al.lanl,designofspswithpenningdischarge,fast,compactgasvalve,0.1ms,0.8khz,1-currentfeedthrough;2-housing;3-clampingscrew;4-coil;5-magnetcore;6-shield;7-screw;8-copperinsert;9-yoke;10-rubberwasher-returningsprings;11-ferromagneticplate-armature;12-vitonstop;13-vitonseal;14-sealingring;15-aperture;16-base;17-nut.,photographofafast,compactgasvalve,cspswithpenningdischarge,dischargevoltage,dischargecurrent,extractionvoltage,extractioncurrent,h-currentaftermagneticanalyzer,noiselessoperation,100hz,testedfor300hsofcontinuousoperationwithh-current100ma,beamformationanddiagnosticsofspswithpenningdischarge,emittancemeasurement,directbrightnessdetermination,ionbeamcollector1withcollimatorforj.collector2withcollimators1forbbeamletdeflectorhorizontaldeflectorverticalscreenwithcollimators2forbdetectioncollector3forbdetection.b=il2/s1s2,s1=s2=0.1x0.1mm2,l=250mm,i10-6a.,emittancediagramms,h-beamcurrent80ma,energy23kev,0.5x10mmmmxn90%=0.06mmmradyn90%=0.2mmmradtx16ev,ty2ev,beaminstabilitywithasecondaryelectronemission,beaminstabilitywithcurrentdensityfluctuation,beamcurrentdensitydistributionfordifferentcurrents/extractionvoltages,dependenceofcurrentandpickcurrentdensityfordifferentextractionvoltagesondischargecurrent,binpversionpenningdtspsforumd,1-cathode;2-anode;3-extractor;4-groundext.;5-magnet;6-insularors;7-cooler.1ms,10hz,1a/cm2teff1ev,designoffermilabmagnetronwithaslitextraction,fermilabmagnetronwithaslitextraction,y,mm,simulationofh-ionbeamextractionfromtheslitmagnetron,electrodestrajectoriesandequipotentials,slit2x10mmi=87mau=21kvneutral95%,0,10,5,0,5,x,mm,y,mm,0,2,2,currentdensity,emittanceplot,-2.5,2.5,-250,250,x,mm,x,mrad,j,a/cm2,dischargeparametersandbeamintensityinfermilabmagnetron,200,100,80,0,0,time,mks,beamcurrent,ma,time,mks,0,beamintensityvsdischargecurrentandextractionvoltageinfermilabmagnetron,extractionsystemofbnlmagnetron,h-currentvsextractionvoltageformagnetron,h-current,ma,extractionvoltage,kv,designofthefirstversionofsemiplanotronsps,1-cathode5cmlong;2-anode-dischargechamber;3-magneticinsert;4-magneticpoles;5-emissionslit,d=0.5mm;6-extractor;7-cylindricalgroveforplasmaconfinement;8-plasmatrapfordischargetriggering.h-beamupto0.9a,1ms,10hz,slit0.7x45mm2;0.22a,slit1x10mm2.,v.dudnikov,inp,1976,nibeamintensityasfunctionofdischargecurrentinthesemiplanotronsps,designofasemiplanotronspsforaccelerators,semiplanotronspswithaslitextraction,beamcurrentvsanarccurrentfordifferentslitgeometryinthesemiplanotron,dependencesofthe-ionbeamcurrentonthedischargecurrenthavethen-shapedformwiththreesections:lineargrowthatsmalldischargecurrents,saturationorafallingsectionatmediumcurrents,andlinear,butslowgrowthatthehighcurrents.,d-,d+,e,h-,plasmasource,ionizer,sps,solenoid,extractor,analyzer,polarizednegativeionsourcewitharesonanceionizer,a.belov,v.dudnikov,et.al.,dcspswithahighemissioncurrentdensity,anodeofdcsps,collectorcurrenticvs.dischargecurrentidandextractionvoltagevex,extractionapertureofd=1mm,extractionapertureofd=0.4mm,compactdcspswithhollowcathodedischarges,1-cylindricalcathodebody;2-channelforcesiumdelivery;3-channelforworkinggas;4-insulator(ring);5-anodechamber;6-hollowcathodechannel;7-driftedplasma;8-extractionaperture;9-sphericalemitter;10-magneticpole;11-extractor;12-ionbeam.,assemblyofthenegativeionsourceinvacuumchamber,brookhaventechnologygroup,1-gastube;2-electricvacuumfeedthroughs;3-highvoltageflange;4-highvoltageinsulator;5-highvoltagefeedthrough;6-baseflange;7-coolingrods;8-cscatalystsupply;9-cathode-emitter;10-cathodeinsulator;11-gasdischargechamberanode;12-magnetpoles;13-suppressionelectrode;14-extractionelectrode;15-permanentmagnet;16-highvoltageinsulators;17-baseplate-magneticyoke;18-ionbeam;19-vacuumchamber;20-highvoltageinsulator.,typicalassemblingofcspsonthevacuumflange,emittanceofdcsps,25kev,1.5ma,(duosps)possibleadaptationofnieintherealduoplasmatron,spswithheliconplasmagenerationandion/atomconverter,ionfluxconversiontofastatomsinconverter.laserdiagnosticsandcontrolcesiumdistribution.cesiumtrappingbyfullionizationwithlaserexcitationindischargechamber.laserbeamattenuationforcontrolcesiumdensitywithoutdischarge.,helicondischargeplasmasourceforsps,adischargeinhydrogengaswithhelicontypeantennainlongitudinalmagneticfieldwa