PPPLtodesignahigh-resolutiondiagnosticsystemfortheNationalIgnitionFacilityByJohmGreenwaldNovember16,2015

KennethHillandManfredBitterinspectanX-raycrystalspectrometertobeusedtostudyOMEGAEPlaser-producedplasmas.(PhotobyElleStarkman/OfficeofCommunications)TwoU.S.DepartmentofEnergy(DOE)laboratoriesworkingonverydifferenttypesoffusionexperimentshavebegunanovelcollaboration.Underthearrangement,theDOE’sPrincetonPlasmaPhysicsLaboratory(PPPL)willdesignadiagnosticsystemtoprovidehigh-resolutionanalysisofresearchontheNationalIgnitionFacility(NIF)atLawrenceLivermoreNationalLaboratory(LLNL).ThisworkissupportedbytheDOEOfficeofScienceandLLNL.NIFistheworld’smostenergeticlaser.NIFisfundedbytheNationalNuclearSecurityAdministration(NNSA),theagencychargedwithensuringournation’snuclearsecurity.ThechiefmissionofNIFistoprovideexperimentalinsightanddataforNNSA’sscience-basedStockpileStewardshipProgramintheareaofhigh-energy-densityphysics,ascientificfieldofdirectrelevancetonucleardeterrenceandnationalnuclearsecurity.

PPPLhasusedsuchdiagnosticsystems,calledX-raycrystalspectrometers,fordecadestostudythedatafromthelaboratory’smagneticfusionresearch.TheseexperimentsheatelectricallychargedplasmatotensofmillionsofdegreesCelsiusandconfineitwithmagneticfieldstomaketheatomicnuclei—orions—intheplasmamergeandreleasetheirenergy.High-powerlasersNIF,bycontrast,isdevelopingatechniquecalledinertialconfinementfusionthatisquitedifferent.NIFfires192high-powerlasersattinypelletsoffueltocompressthetarget,therebyheatingtheplasmaandcausingtheionsinsideittofuse.ThePPPLspectrometerwillanalyzeandrecordthedatafromtheseNIFexperimentsinhigh-resolutiondetail.SpectrometersnowinuseatNIFhavelowerresolution.CreatingthenewspectrometerarephysicistsKennethHillandManfredBitter,whosediagnosticdesignsareusedinmagneticfusionexperimentsaroundtheworld.“ThisisbasicallyPPPLexpandingitsdiagnosticequipmentintohigh-energy-densityphysics,”saidPhilEfthimion,headofthePPPLPlasmaScienceandTechnologyDepartment.“KenandManfredhavetheexperienceandknowledgetotakethetechnologytheydevelopedmorethan20yearsagoandextendittotheverybrightandhigh-energyX-raysthatNIFproduces.”Thespectrometerthetwophysicistsaredesigningwillfitintotightquarters.WhiletheNIFlasersarehousedinabuildingthesizeofthreefootballfields,thepelletatwhichtheyaimisonlyamillimeterindiameter,orabout4hundredthsofaninch.Thetargetshrinkstoone-tenthofamillimeterwhenstruckbythebeams.Tostayclearofthebeamswhilerecordingthedata,thespectrometerwillbepositionedinanarrowchamberandsetinsideaholderthatislessthanafootindiameter.Partofamulti-prongedeffortThisresearchispartofamulti-prongedeffortintheongoinginertialconfinement(ICF)program,whichisusedtostudyignitionandburninalaboratorysetting,andwhichaimstotacklearguablythemostchallengingobservableconditioninICFimplosions—stagnation,theterminationofthecompressionprocessbeforefusiontakesplace.Thespectrometerwillbeusedtoidentifythequantitativecharacteroftheimplosionasit“stagnates”overasmallvolumefortheveryfirsttime.Thespectrometer,whichcouldbecompletednextfall,willcollectdatafromICFandotherexperimentstobeconductedatNIF.Forexample,geophysicistsstudyingtheintensedensityandpressureatthecoreoftheEarthwillbeabletousetheNIFlaserstocreatelaboratoryconditionsthatproducesimilarextremestatesofmatter.

ThespectrometerforNIFwillbethesecondforhigh-energy-densityphysicsthatHillandBitterhavedesigned.TheypreviouslycollaboratedindesigninganX-raycrystalspectrometer,andevaluatedoneoftheprecisionsphericallybentcrystalstobeusedinthespectrometer,fortheOMEGA-EPlasersystemattheUniversityofRochester,whichsupportsinertialconfinementresearch.Thisspectrometerwillnowundergoafinaldesignreview,withtestingandinitialphysicsmeasurementsonOMEGAscheduledforearly2016.PPPL,onPrincetonUniversity'sForrestalCampusinPlainsboro,N.J.,isdevotedtocreatingnewknowledgeaboutthephysicsofplasmas—ultra-hot,chargedgases—andtodevelopingpracticalsolutionsforthecreationoffusionenergy.ResultsofPPPLresearchhaverangedfromaportablenuclearmaterialsdetectorforcounterterrorismuse,touniversallyemployedcomputercodesforanalyzingandpredictingtheoutcomeoffusionexperiments.TheLaboratoryismanagedbytheuniversityfortheU.S.DepartmentofEnergy’sOfficeofScience,whichisthelargestsinglesupporterofbasicresearchinthephysicalsciencesintheUnitedStates,andisworkingtoaddresssomeofthemostpressingchallengesofourtime.Formoreinformation,pleasevisitscience.energy.gov.###EstablishedbyCongressin2000,NNSAisasemi-autonomousagencywithinDOEresponsibleforenhancingnationalsecuritythroughthemilitaryapplicationofnuclearscience.NNSAmaintainsthesafety,security,andeffectivenessoftheU.S.nuclearweaponsstockpilewithoutnuclearexplosivetesting;workstoreduceglobaldangerfromweaponsofmassdestruction;providestheU.S.Navywithsafeandeffectivenuclearpropulsion;andrespondstonuclearandradiologicalemergenciesintheU.S.andabroad.