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Raskas ionikiihdytin



Introduction

Adevicethatartificiallygeneratesabeamoffastheavyions(ionswithamassgreaterthanalphaparticles).Itusesacertainformofelectromagneticfieldtoaccelerateheavyions,andcanprovidehigh-energyheavyionbeamswithspeedsuptothousands,tensofthousandsorevencloseto300,000kilometerspersecond(thespeedoflightinavacuum)tobombardnuclei,atoms,Molecules,solidcrystallatticesandevenbiologicalcellsareimportanttoolsforpeopletotransformatomicnucleiand"fundamentalparticles"andunderstandthedeepstructureofmatter.Theyarealsoimportantandextensiveinvariousaspectssuchasindustrialandagriculturalproduction,medicalandhealth,scienceandtechnology,andnationaldefenseconstruction.application.

Foraccelerators,thebiggestdifferencebetweenheavyionsandlightionssuchasprotonsistheircharge-to-massratio(Q/A).HereQisthechargestateoftheion,andAisitsatomicmassnumber.Theaveragekineticenergyobtainedbyeachnucleusisproportionaltothecharge-to-massratio(Q/A)oftheacceleratedion.Butingeneral,thecharge-to-massratioofheavyionsisfarlessthan1(thecharge-to-massratioofprotonsis1),andsomeareevenlessthan0.1.Inordertoimprovetheefficiencyofacceleration,itisnecessarytoincreasethecharge-to-massratio,generallybyincreasingthechargestate.Themethodistouseagasorsolidtargettostripelectronsduringtheparticleaccelerationprocess,andthecharge-to-massratioofthestrippedheavyionscanbeincreased.Furtheraccelerationonthisbasiscaneffectivelyincreasetheaveragekineticenergypernucleus.Thedevelopmentofparticleacceleratorsinmycountryhasmadegreatprogresssincethe1980s.Atpresent,theLanzhouHeavyIonAcceleratorhasthelargestscale,themosttypesofacceleratedparticles,andthehighestenergyinChina.Duringthedevelopmentofthisaccelerator,scientificresearchersandengineeringtechniciansadheredtotheprincipleofcombiningself-reliancewiththeintroductionandassimilationofforeignadvancedtechnology,andovercamenumerousdifficultieswiththeirowningenuityandfightingspirit.ItwasfirstintroducedonDecember12,1988.Theenergyis50MeVpernucleusofcarbonions,thusproclaimingtotheworld:Chinahasbuiltthethirdlarge-scaleheavyioncyclotronafterFrance(beamedin1982)andJapan(beamedin1986).Thedevelopmentandapplicationoftheworldacceleratorisadvanced.ThisachievementisanimportantmilestoneinthedevelopmentofChinaandtheworld'sacceleratortechnology.

Komponentit

Yleisten hiukkaskiihdyttimien tapaan raskaissa kiihdyttimissä on kolme peruskomponenttia:

1.Ionilähdetarvittavan kiihtyvyydentarjoamiseenHeavyions.

2.Vacuumaccelerationsystem,avacuumchamberequippedwithanaccelerationstructure,suchasanaccelerationtube,anaccelerationcavity,etc.,isusedtoapplyacertainformofaccelerationelectricfieldtotheparticles,andtheparticlesarenotscatteredbyairmolecules.Accelerateundertheconditions.

3.Guidanceandfocussystem,includingelectromagneticlens,dominantmagneticfield,etc.Acertainformofelectromagneticfieldisusedtoguideandconstraintheacceleratedparticlebeam,sothatitwillbeacceleratedbytheelectricfieldalongapredeterminedtrajectory.Mostacceleratorsarealsoequippedwithabeamtransportsystemcomposedofanumberofbendingmagnetsandelectromagneticquadrupolelenses,whichareusedbetweenthesourceandtheaccelerator,betweentheacceleratorandthetarget,orwhenmultipleacceleratorsworkinseries.Transporttherequiredparticlebeambetween.Inaddition,inordertoensurethestableoperationoftheaccelerator,thereareusuallyelectromagneticfieldstabilizationequipment,beamcurrentdiagnosisandmonitoringequipment,andvariouspowersupplyandoperationequipment.

Toimintaperiaate

Laite, joka tuottaa tietyn energian ja tietyn voimakkuuden raskaalle (A>4ioni)säteelle.Raskaskiihdytin kiihtyvyysperiaate ja rakenne ovat periaatteessa samat,jokakorjaus. ilmaisuja ja valoja, kuten protonja niiden massasuhteeseen (Q/A),jossaQon ionin varaustila jaAonatomimassaluku.Yleensä raskaiden ionien varaus-massasuhde on pienempi kuin1 (protonien massasuhde=1).Keskustelun helpottamiseksi Eei pehmennetty hiukkasten kineettisen energian sijastaE.

En=E/A,

LinekiihdytinToisin sanoen,ydinenergiaVjoka vetää ulos säteenkiihdyttävästä jännitteestä.Ympyräkiihdyttimille,jossakon suhteellinen()2,(Bρ)onsuorittaakseen magneettisen jäykkyyden. ionisäde samoillaydinenergiallaprotoneilla, sinun täytyy joko suurentaa magneettikentän tai pyöreän kiihdytin ,tailisääkiihdytysjännitettä.Tämä nostaa huomattavastikiihdyttimen kustannuksia,jatulevaisuudessa järjestelmän päivittäiset käyttökustannukset ovat todellakin melko kalliita.Jos haluat pienentää kustannuksia,onparempi nostaa(Q/A)-arvoa.

Parannussuunnitelma

Kiihdyttimessä on kaksi tapaa parantaa latauksen massasuhdettaQ/A.

(1)Increasethechargestateoftheheavyionsource.Anidealheavyionsourceshouldbeabletoprovideabeamofdifferentionswithhighintensity,longlife,andhighchargestates.Generally,electronsareusedtobombardatomsandionsintheplasma,orafastionstrippingmethodcanbeusedtoobtainahighchargestateionflow.Thefluxdensityoftheelectronbombardmentsourceisverydemanding.TheheavyionsourceusedintheheavyionacceleratorisaPIGsourceandadualplasmasource.ThefollowingtableshowsthechargestatedistributionofseveraltypicalheavyioncurrentsderivedfromthePIGheavyionsource.

(2)Strippingtheouterelectronsofions(thatis,thestrippingofatoms).Commonlyusedstrippersaresolid(suchascarbonfilm)andgas.Theaveragechargestateandthedistributionofthechargestateoftheionafterstrippingtheouterlayerofelectronsaremainlydeterminedbytheincidentenergyoftheparticle.Generallyspeaking,thehighertheenergy,theaveragecharge.Thehigherthestate.Thestrippingefficiencyofthesolidstripperishigherthanthatofthegasstripper,buttheangulardispersionandenergydispersionoftheionsafterthestrippingarelarger.

Thesetwowaysofimproving(Q/A)arenowwidelyusedinheavyionaccelerators,especiallythelatter.Becausetheaveragechargestateafterstrippingisdeterminedbytheincidentenergy,heavyionacceleratorsgenerallyadoptacombinationmethod,thatis,twoormoreacceleratorsareconnectedinserieswithastripperinthemiddle.Theformeracceleratoriscalledtheinjector,andthelatteracceleratoristhemainaccelerator.Theheavyionsourceisinstalledintheimplanter,ortheheavyionsareinjectedintotheimplanterexternally.Aftertheionsareacceleratedbytheimplanter,theyreachacertainenergy,andtheionsarestrippedintohigh-chargedheavyionsthroughthestripper.Then,itentersthemainacceleratortoaccelerateandobtainheavyionswithhigherextractionenergy.

Electrostaticaccelerator

Amongallkindsofheavyionaccelerators,theelectrostaticacceleratorischaracterizedbydirectcurrentoperation,whichcanprovidevariousheavyionbeamswithsmallspotsandhighenergyaccuracy.

Thelinearacceleratorbeamintensityislarge,andtheparticletypesarerarelylimited.Therefore,thefirstall-ionacceleratorthatcanacceleratetheionsofallelementsontheperiodictableisalinearaccelerator.Thistypeofacceleratorisalsoahigh-energyheavyion.Themainacceleratorintheinstallationisanidealinjectorforsynchrotron.However,ionscanonlybeacceleratedonceintheaccelerationstructureoftheaccelerator,andcannotbeacceleratedrepeatedly,andtheelectricalefficiencyislow.Manylaboratoriesareworkingonmoreeffectivelinearacceleratorresearch.Intermsofhigh-frequencypower,acyclotronisveryeconomical,becauseionsonlyneedtorepeatedlypassthroughthesameaccelerationstructuretocontinuouslyincreasetheirenergy,anditsmaximumcostisdeterminedbythesizeofthemagnet.Whentheionenergyisrequiredtobehigh,andthetypeandenergyarevariable,themagneticfieldchangecausedbytheincreaseoftherelativisticmassrequiresaverysophisticatedmagneticfieldshapingtechnology.

Synchronizersaremoreeconomicalintermsofhighfrequencyandmagnetconstruction.Itisanidealacceleratorforobtaininghigh-energyheavyions.

Superconductingacceleratorsareusedasheavyionaccelerators.Becauseoftheirgreateconomicandtechnicaladvantages,theyhavereceivedextensiveattention.Itcangenerateahighacceleratingelectricfieldataverylowmicrowavepower,orahighconfinementmagneticfieldataverylowexcitationpower.Thesewillreducethesizeoftheaccelerator,reducepowerconsumptionandoperatingcosts,anditisapromisingheavyionaccelerator.

Examples

Sector-focusedcyclotron

Mostofthenewandrebuiltheavyionacceleratorsintheworldareisochronouscyclotrons(ie,sector-focusedcyclotrons).Thesecondisthetandemelectrostaticaccelerator.Inordertoobtainhigherenergy,manynewlybuiltdevicesusetwoormoreacceleratorsconnectedinseries.Toformaheavyionacceleratorsystem,somearetandemelectrostaticacceleratorsinjectedintoacyclotronorlinearaccelerator,andothersaretwocyclotronsinseries.

Inordertotransmitthebeamfromtheinjectortothemainaccelerator,abeamtransportsystemisneededtochangetheshapeofthebeamfromtheinjectortomeetthebeamrequirementsofthemainaccelerator.Inaddition,inordertoreducetheionlosscausedbythechargeexchange,theacceleratorandthebeamtransportsystemrequireahighdegreeofstraightness,generallyaround1×10-7Torr.Thereshouldbeachargeanalysisdeviceonthetransmissionline.Thestructureoftheheavyionacceleratordeterminesthatitsdebuggingandoperationaremorecomplicated.Generally,anautomaticcontrolsystemshouldbeequippedtocontrolthedebuggingandoperation.Ofcourse,thebeamdiagnosticequipmentintheacceleratorandonthetransmissionlineisindispensable.Less.

LanzhouHeavyIonAccelerator

TheLanzhouNegativeIonResearchFacility,alsoknownastheLanzhouHeavyIonAccelerator,isthelargestheavyionresearchfacilityinChinawiththehighestenergy.Therearecurrently8similarmedium-energyheavy-ionacceleratorsintheworld,andHIRFListhefourthintheorderofcompletiontime.France,Japan,andmycountryalluselarge-scaleseparationfancyclotronsastheirmainaccelerators.Sincethe1960s,withthedevelopmentofheavyionaccelerators,nuclearphysicshasopenedupanewandvigorousfield-heavyionphysics.Inotherdisciplines,suchasatomicphysics,materialsscience,lifesciences,newenergyresearch,astrophysicsandotherfields,heavyionbeamshavealsoshownincreasinglyimportantapplicationprospectsandhaveformedimportantinterdisciplinarysubjects.Inorderformycountrytooccupyaplaceinthisfrontierfield,theStateInvestmentandInstituteofNearMaterialswereresponsibleforthedesignandconstruction.In1988,theLanzhouHeavyIonAccelerator(HIRFL)wasbuilt.Itsmaintechnicalindicatorsreachedtheinternationaladvancedlevelatthattime.SpecialPrizeforProgress,wontheFirstPrizeofNationalScienceandTechnologyProgressin1992.TheLanzhouHeavyIonAcceleratorNationalLaboratorywasestablishedin1991.Itspositioningistofocusonthebasicandappliedresearchofheavyionphysics,developparticleacceleratorsandexperimentaltechnologyaccordingly,andbeacomprehensivescientificresearchbaseopentodomesticandforeign.Inthe1990s,aninternationallyadvancedradioactivebeamstreamline(RIBLL)anda14.5GHzhigh-chargestateECRionsourcewerebuiltonHIRFL,bothofwhichwonthefirstprizeofscientificandtechnologicalprogressoftheChineseAcademyofSciences.Theresearchintheinternationalfrontierfieldsofionizedstateatomicphysicshascreatedadvancedexperimentalconditions.LanzhouHeavyIonAcceleratorCoolingandStorageRing(HIRFL-CSR)-isthecountry’slargestscientificprojectduringtheNinthFive-YearPlan.LanzhouNationalLaboratoryofHeavyIonAcceleratorhasdevelopedintooneoftheheavyionphysicsresearchcentersenjoyingahighreputationintheworld.

Medicalheavyionaccelerator

China’sfirstself-developedmedicalheavyionacceleratorwassuccessfullylaunched.Thismeansthatheavyionradiotherapyfortumorpatientswillnolongerrelyonforeigntechnologyandequipment.

ThismedicalheavyionacceleratorislocatedinWuweiCity,GansuProvince,anditsdevelopmentbeganinMay2012.Atpresent,400MeVpernucleuscarbonionbeamaccelerationandnonlinearresonanceslowextractionhavebeenachieved,whichhasreachedthedesignindex.Thedevicecanbeusedforheavyionradiotherapyfortumorpatients,especiallyfortumortypesthataredifficult,unsuitableforsurgery,andpronetorelapseusingothertreatmentmethods.

Previously,onlyShanghaiFudanUniversityCancerHospitalhadasetoffullyimportedmedicalheavyionacceleratorequipmentinChina.Independentresearchanddevelopmentisthefirstcase.

RelevantresearchersfromtheInstituteofNearPhysicsoftheChineseAcademyofSciencessaidthatthisheavyionacceleratoristheresultoftheaccumulationandinheritanceoftheinstitute’snearly60yearsofscientificresearchexperience.Aftertheheavyionacceleratorissuccessfullyreleased,youcanapplyfortheStateFoodandDrugAdministrationtotest.Afterthetestmeetsthestandard,clinicaltrialswillbecarriedout,andthetestindicatorscanbeofficiallyusedtoreceivetreatmentforcancerpatients.

Itisunderstoodthatintermsoftumortreatment,theenergydepositionandaccuracyofheavyionsarebetterthanprotonsthathavebeenusedformanyyears,andthetechnologyisrelativelymature,whichhasobviousadvantagesinphysicsandbiology.

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