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(Bρ)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.