WrittenTestimonyofDr.TammyMaProgramElementLeaderforHigh-IntensityLaserHighEnergyDensityScience,NationalIgnition

Facility&PhotonScienceLawrenceLivermoreNationalLaboratory

Deliveredtothe

CommitteeonScience,Space,andTechnologySubcommitteeonEnergyUnitedStatesHouseofRepresentatives

HearingonFosteringaNewEraofFusionEnergyResearchandTechnologyDevelopment

November17,2021

ChairmanBowman,CongressmanWeber,andMembersoftheCommittee,thankyoufortheopportunitytotestifybeforeyoutodayaboutfusionenergy.MynameisTammyMa,andIamcurrentlytheProgramElementLeaderforHigh-IntensityLaserHighEnergyDensityScienceattheNationalIgnitionFacility(NIF)atLawrenceLivermoreNationalLaboratory(LLNL).Ihavebeeninvolvedininertialconfinementfusion(ICF)experimentsontheNIFsinceexperimentalcampaignscommencedonthefacilityin2009,andIcurrentlyserveontheDOEOfficeofScience’sFusionEnergySciencesAdvisoryCommittee(FESAC).IwanttostressthattodayIampresentingmyownopinionsandnotnecessarilythoseofLLNL.Withmytestimony,Ihopetoconveyseveralpoints:

• RecentbreakthroughresultsfromNationalIgnitionFacility(NIF)inertialconfinementfusion(ICF)experimentshavedemonstratedcapsulegainandburningplasmas;theyhaveplacedusonthethresholdoffusionignitionwhereenergygainfromnuclearfusioninthecapsuleexceedsthelaserenergydelivered.

• Achievingfusionignitionisthefirstmajorhurdleinefficientlyharvestingfusionenergythroughinertialfusionenergy(IFE),aninnovativeapproachthatiscomplementarytomainstreammagneticfusionenergy(MFE)research.Currently,IFEisnotpartofthelong-termenergyR&DportfoliooftheU.S.andisnotpartoftheresearchbeingpursuedatLLNL.

• TheUnitedStatesistheworldleaderinhighenergydensitysciencewhichunderpinsthephysicsoffusionignition,thankstoinvestmentsbytheNationalNuclearSecurityAdministration(NNSA)andtheDOEOfficeofScience.Weareexploitingtheseextraordinarycapabilitiestoperformworldleadingscienceanddevelopadvancedtechnology.However,theU.S.leadisbeingchallengedandcompetitionisfierce.

• NIF’smissionisscientificresearchofICFtosupporttheStockpileStewardshipProgram(SSP).ItdiffersfromwhatisneededforanIFEpowerplant.DevelopingIFEtowardthegoalofacleanenergysourceisadistinctchallenge,yetonethatishighlysynergisticwithNNSA’sSSPmissionundertheICFprogram.

• ThetimeisrighttorestartanIFEprogramintheU.S.–decadesofexpertiseinICFwhichhasbroughtustothethresholdofignitioncombinedwithadvancesinourcomputingmodelingcapabilitiesandnewemergingtechnologiessuchasnovellaserarchitecturesofrelevancetoIFE,machinelearning,innovativediagnostics,andagrowingcommunityofskilledresearcherscanenablerapidprogress.

• Throughtherecent2020FESACLongRangeStrategicPlan,thefusioncommunitystronglyendorsedthere-establishmentofanIFEprogram.

TheNationalIgnitionFacility(NIF)AchievestheThresholdofIgnitionThispastAugust,abreakthroughfusionexperimentachievedayieldof1.35megajoulesontheNationalIgnitionFacility(NIF),morethantwo-thirdsofthe1.9megajoulesoflaserenergydepositedonthetarget,andeighttimesmorethanthepreviousrecord(seeFigure1).ThisresultplacesNIFonthethresholdoffusionignitionforthefirsttime,anddemonstratesthefeasibilityoflaboratory-scalelaserdriveninertialconfinementfusiontoachievehigh-yieldconditions.TheNIFisafootball-stadium-sizedfacilitythathousestheworld’slargest,mostenergeticlaser(approximately60timesmoreenergeticthananyotherlaserintheworldwhenitwascompletedin2009).Theprecisionandrepeatabilityofthislasersystemareunprecedentedintheworld.NIF’s192laserbeamsareguidedandamplifiedthroughthousandsofopticalelementsandthenfocusedontoaminiature,highlyengineeredtargetthesizeofaBB.Insidethistargetisasphericalcapsulecontainingthefusionfuel.Theresultisahotspotthediameterofahumanhairthatcreatesconditionshotteranddenserthanthosefoundatthecenterofthesun.ThecentralmissionoftheNIFistoprovideexperimentalinsightanddatafortheNationalNuclearSecurityAdministration(NNSA)’sscience-basedStockpileStewardshipProgram(SSP).Experimentsinpursuitoffusionignitionareavitalpartofthiseffort.Theyprovidedatainanimportantexperimentalregimethatisextremelydifficulttoaccess,furtheringourunderstandingofthefundamentalprocessesoffusionignitionandburn,andenhancingthesimulationtoolsthatsupportourstockpilestewardshipmission.Fusionignitionisthegatewaytowardevenhigherfusionyieldsinthefuture.Whilefullscientificinterpretationoftheselatestresultsisstillongoingandwillbevettedthroughthescientificpeer-reviewedprocess,initialanalysisshowsthatthisexperimentgeneratedmorethan10quadrillionwattsoffusionpowerfor100trillionthsofasecondfroma50micron-sizeburningplasma.Thisequatestoanimprovementofeighttimesoverexperimentsconductedinthespringof2021anda25-foldincreaseovertheyieldfromayearago.Thisshotalsoachievedcapsulegain(definedastheratioofenergyreleasedovertheenergyabsorbedbythecapsule)exceedingafactoroffive.BytheNationalAcademyofSciences1997definitionofignition(whereintheenergy

Figure 1. Shot N210808 on NIF produced more than 1.35 megajoules of fusion yield and marks a significant advance in ICF research. The histogram shows the progress over a decade of dedicated research and development on the NIF.

outofthetargetisequaltothetotallaserenergyincidentonit),thegainwas70%ofthatneededforignition.TheexperimentbuiltonseveraladvancesgainedfrominsightsdevelopedoverthelastfewyearsbytheNIFteam,includingnewdiagnostics;fabricationimprovementsinthetargetthatincludethehohlraum,capsuleshell(whichcontainsthedeuteriumandtritiumfuel),andfilltube(bywhichthecapsuleisfilledwiththefusionfuel);improvedlaserprecision;anddesignchangestoincreasetheenergycoupledtotheimplosionandthecompressionoftheimplosion.Theserecentresultsnowalsoopenavastnewfrontierforscientificexplorationandexploitation.ThesamefusionplasmasthatwecreateforICFnationalsecurityapplicationscanalsobeexploitedtobecomethebasisofafuturecleannuclearpowersource,whichwillalsocontributetodomesticenergyindependenceandsecurity.ProgressinInertialConfinementFusion(ICF)laysthegroundworkforInertialFusionEnergy(IFE)Asweapproachinertialconfinementfusion(ICF)ignitionontheNIF,thiswillrepresentthefirsttimeinthelaboratorythatafusionreactionwillreleasemoreenergythanwasusedtogeneratethereaction.Thisbreakthroughformsthebasisofapossiblepathtofusionenergythathassignificantlydifferenttechnologicalandengineeringriskportfoliosthantheconceptsbeingpursuedformagneticfusionenergy.Tobeclear,however,NNSAdoesnothaveanenergymissionand,therefore,noNNSAresourcesarebeingusedforinertialfusionenergy(IFE)researchatLLNL.Itmustbeacknowledgedthat,likeallapproachestofusionenergy,therearemanyscientific,technological,andengineeringchallengestoIFE.AnIFEsystemwouldworkbyusingadriver(suchasalaser)toimplodeaninjectedtargettofusionignitionandhighenergygainconditionsmanytimespersecond.Netelectricalenergygainshouldbepossiblewhentheratiooffusionenergyreleasedtoinputdriverenergyisontheorderof100timestheinputenergy.Tomakethispossible,significanttechnologicalhurdlesneedtobeovercome:ignitionschemeswithhighyieldandrobustmarginmustbedeveloped;driversmustbedevelopedthathavehighefficiencyandthatcanbeoperatedatrepetitionratesofseveraltimespersecond;ignition-qualitytargetsmustbeeconomicallymassproduced,efficientlydriven,andstablyimplodedthatyieldhighgainattherateofmanytimespersecond;opticsandhardwareproducedthatcanwithstandcontinualexposuretobothhighopticalirradianceandfusionradiation;andreactorchambersmustbedesignedtocontainthemicro-explosionproductsandadequatelyprotectthedriver.Furthermore,eachofthesesystemswillhavetobeengineeredwithcost,operability,andmaintainabilityinmindrequiredforeconomicalenergyproduction.TheNationalAcademyofSciencesstudiedthisproblemandreleasedanexcellentreportin2013entitled“AnAssessmentoftheProspectsforInertialFusionEnergy.”Anumberoffindingsandconclusionsweremade,includingonethat“Thepotentialbenefitsofenergyfrominertialconfinementfusion(abundantfuel,minimalgreenhousegasemissions,andlimitedhigh-levelradioactivewasterequiringlong-termdisposal)alsoprovideacompellingrationaleforincludinginertialfusionenergyR&Daspartofthelong-termR&DportfolioforU.S.energy.Aportfoliostrategyhedgesagainstuncertaintiesinthefutureavailabilityofalternativessuchasthosethatarisefromunforeseencircumstances.”Thereportwasalsoclearinconcludingthat“Theappropriatetimefortheestablishmentofanational,coordinated,broad-basedinertialfusion

energyprogramwithinDOEwouldbewhenignitionisachieved.”1Thisisthetimetobeginaswestandatthethresholdofignition.Fusionenergyresearchisahigh-stakesendeavor,andassuch,technologicaldiversityisalwaysagoodstrategy.NNSAhasmadeasignificantinvestmentinICF,NIF,andotherICF-relevantfacilitiessuchastheZPulsePowerFacilityatSandiaNationalLaboratories,andtheOmegaLaserFacilityattheUniversityofRochester.TheDOEOfficeofScienceFusionEnergySciencesprogramcanandshouldleveragethistohelpestablishtheIFEpathforward.TheU.S.istheworldleaderinhighenergydensityscience,althoughthatleadisbeingchallengedThestudyoftheextremedensity,temperature,andpressureconditionslikethosefoundinICFplasmasiscalledhighenergydensity(HED)science.U.S.investmentssupportedbyNNSAandtheDOEOfficeofSciencehavemadetheU.S.theworldleaderinthisareaofscience,givingtheU.S.acompetitiveadvantage.Asanexample,whencompletedin2009,NIFoperatedwith60timesmoreenergythanthenextbiggestlaserintheworld,whichwastheOmegaLaserFacility,alsointheU.S.Now,nearlyadecadelater,NIFoperateswith10to20timestheenergyofthenextmostenergeticlaser,whichisinChina.TherearefewfieldsofsciencetodaywheretheU.S.hashad,andcurrentlymaintains,suchalargeleadovertherestoftheworld.Thisleadexistsnotonlyinfacilitycapabilitiesbutalsoindiagnostics,targets,simulations,andscientificoutputandpublications.Thisworldleadershipalongwiththecompellingscientificopportunities–especiallythegrandchallengeofinertialconfinementfusionignitionandthepotentialofapathtoinertialfusionenergy–hasbeenamagnetforthebestandbrightestscientistsandengineerstopursueresearchinHEDscienceandtoworkaspartoftheSSP.TheworldleadingnatureofNNSA’sICFfacilitiesrequirescuttingedgescienceandtechnologythatinturnleadstomanyspinoffbenefits.Forexample,NIFrequiresuniquecapabilitiesinlasers,optics,precisiontargetfabrication,diagnostics,andcomputercontrols.DevelopmentsintheseareashaveledtoalargenumberofR&D100awardsovertheyearsandaproliferationofideasthatsupportournationalsecurity(e.g.,directedenergyweapons)andoureconomiccompetitiveness(e.g.,extremeultravioletlithography,anapproachtohelpextendMoore’slawinchipmaking,isaspinoffofinertialconfinementfusionlaserresearch).WhilehistoricallywehavehadanimpressiveleadinHEDscience,itiscleartodaythattherestoftheworldisaggressivelyfocusingoncatchingup.Currently,megajoule(NIF)scalelasersareunderconstructioninbothFranceandRussia.TheChinesehavecompletedandareoperatingthesecondmostenergeticlaserintheworldandarepublishingpaperswithdesignsforlasers50%tothreetimesthesizeofNIF.Havingmoreenergymakesachievinginertialconfinementfusionignitioneasier.Theareaofhighintensitylasersisaparticularlynoteworthyexample.ResearchersintheU.S.pioneeredthefieldofhighintensitylasers.Theselasersreachmoreextremeconditionsnotbyincreasingtheenergydelivered,butbyreducingthedurationofthelaserpulse,achievinghigherandhigherpowersasthedurationisreduced.Inthe1990s,LLNLbrokethepetawatt(10^15watts)barrierwiththeconstructionoftheNovaPetawatt.Anumberofnovelandimportantnew

1 An Assessment of the Prospects for Inertial Fusion Energy, Committee on the Prospects for Inertial Confinement Fusion Energy Systems; NAS (National Academies Press, Washington, D.C., 2013).

propertiesemergedatthehighintensitiesthatthesenewlasersenabled,andsincethendozensofpetawattclasslasershavebeenbuiltandthousandsofpublicationsabouttheexcitingscienceinthisareawerepublishedoverthenext20years.In2017,theNationalAcademyofSciencespublishedareporton“OpportunitiesinIntenseUltrafastLasers:ReachingfortheBrightestLight.”Akeyconclusionfromthisreportisthat:

“TheU.S.haslostitspreviousdominance.TheUnitedStateswastheleadinginnovatoranddominantuserofhigh-intensitylasertechnologywhenitwasdevelopedinthe1990s,butEuropeandAsiahavenowgrowntodominatethissectorthroughcoordinatednationalandregionalresearchandinfrastructureprograms.InEurope,thishasstimulatedtheemergenceoftheExtremeLightInfrastructure(ELI)program.Atpresent,80to90percentofthehigh-intensitylasersystemsareoverseas,andallofthehighestpower(multi-petawatt)researchlaserscurrentlyinconstructionoralreadybuiltareoverseas.”2

TheDOEOfficeofScience’sFusionEnergyScienceProgramhassincestartedtorespond,andweapplaudthemforpushingforwardtheMattersatExtremeConditions(MEC)UpgradeprojectatSLACNationalAcceleratorLaboratory’sLinacCoherentLightSource(LCLS),whichrecentlyachievedCriticalDecision1(CD1)intheprojectstage.Thisprojectwillintegratestate-of-the-arthigh-energy,high-repetition-ratelaserswithSLAC’sx-raylightsourcetoprovideanunprecedentedHEDscienceplatform(seeFigure2).LeveragingtheseadvancedlasersystemsandreapingthepotentialrewardsforHEDscience,however,alsorequirescommensurateinvestmentanddevelopmentinmassivelyparalleltargetfabricationandcharacterization,targetdebrismanagementandmitigation,electromagneticpulse(EMP)andradiationhardeneddiagnostics,andreal-timedatamanagementandanalysiscoupledtosophisticatedsimulationcodes.Thesecapabilitiesarecrucialforenablingthenextfrontierindata-drivenHEDscienceandarealsokeytoadvancingIFE.

2 Opportunities in Intense Ultrafast Lasers: Reaching for the Brightest Light, Committee on Opportunities in the Science, Applications, and Technology of Intense Ultrafast Lasers; NAS (National Academies Press, Washington, D.C., 2017).

Figure 2. The High-repetition-rate Advanced Petawatt Laser System (HAPLS) is the world's most advanced, highest average power, diode-pumped laser system. It was designed, developed, and built by LLNL for the Extreme Light Infrastructure Beamlines (ELI-Beamlines) in the Czech Republic. A higher energy version is planned for the new MEC-Upgrade project at SLAC National Accelerator Laboratory, ensuring an unprecedented HED science capability for the U.S.

ThesynergiesbetweenIFEandICFaremanyandmutuallybeneficialTheNIFisamarvelofscienceandengineering,allowingforresearchatthecuttingedgeofthemostextremeconditionsintheuniverse.However,itisexactlythat–ascientificexplorationfacility,andverydifferentfromwhatwouldbeneededforaninertialfusionenergypowerplant.Asbrieflytouchedonabove,anelectricity-producingIFEpowerplantwouldalsorequire,forexample,amorerobust,high-yieldignitionschemelikelydifferentfromwhatispursuedaspartoftheSSP;adriver,targetinjection,andtrackingsystem,alloperatingathighrepetitionrates;anenergyconversionsystem;robustfirstwallsandblanketsforwallprotection,tritiumprocessingandrecovery,remotemaintenancesystems,andmore.ThedevelopmentofIFEtowardsthegoalofacleanenergysource,isdistinctyethighlycompatiblewithNNSA’sSSPmissionthroughtheICFprogram.ThesynergiesbetweenIFEandICFaremanyandmutuallybeneficial;forexample,advancedtargetsthatcouldyieldhighgainforIFEcouldsimilarlyproducehighneutronyieldforICFapplications,whileimprovementsindrivercostandrepetitionrateforIFEcouldsimilarlymeanmoreHEDexperimentsforSSP.Furthermore,IFEoffersalong-termsolutionforclimatechangeandenergysecurity–importantfactorsintheoverallnationalsecuritylandscape.TheexcitingvisionofIFEalsoservesasanimportantrecruitmentandtrainingtoolformanyDOEmissions.Generationsoflaserandplasmaphysicists,scientistsandengineers,havebeendrawntothefieldfortheopportunitytobeinvolvedwiththebigscienceandchallengingproblemoffusion.ThecurrentU.S.leadershipinHED/ICFresearchstems,inpart,fromthehistoricalpursuitofIFEandassuch,wemustcontinuetotakealeadingroleinIFEtomaintainpreeminenceinthisarena.TheU.S.hasanopportunitynowtogrowthenationalprogrambynourishingandleveragingourleadershipinICFwithuniqueandworld-leadingcompetenciesintheunderlyingscienceandtechnologythatunderpinsIFE.ThetimeisrighttorestartanIFEprogramintheU.S.TheDOEisinanexcellentpositiontomakerapidprogressinthisareabyleveragingthelargeinvestmentbeingmadeinmanyemergingtechnologiesandbytheNNSAinICFresearch.ManyinstitutionsalreadyactiveinHEDresearchwouldbewell-positionedtocontributetothisactivity.AnumberofpromisingtechnologieskeytoeventualIFEsystemsaremakingsteadyprogress.Inparticular,excitingadvancesinrepetition-ratedhigh-energylasertechnologyandrepetition-ratedpulsedpowertechnologyintheU.S.overthelastfewyearspotentiallylowerthecostofafuturedriverforanIFEsystem.Additivemanufacturingandotherautomatedmanufacturingtechniquesarebecomingmorecost-effectiveandarebeingusedaspartofthecurrenttargetfabricationeffortonNIF.Artificialintelligenceandmachinelearningarebeingdeployedtotrainlarge-scale,high-performance,high-speedmodels,improvepredictivesimulationmodels,andquantifyuncertainties.ManycountriesarerampingupeffortsinIFEalongsidemagneticfusionenergy.EUROFusion,aconsortiumofnineEuropeannations,isworkingonaRoadmapforanInertialFusionEuropeanDemonstrationReactor,andChinaandRussiaarealreadybuilding“NIF-like”lasers.Thefusionenergyindustryisrapidlygrowing,alreadyseededbymorethan$2billionofinvestment.Thecompetitionissubstantial,butsignificantpotentialforproductivepartnershipsandprogressinfusionenergyabound.Forexample,whilepublicandprivatestrategiesdifferintechnicalfocusand

deliverables,significantoverlapsexistthatarebeneficialtobothparties.Strategicallypartneringthepublicandprivatesectorscanresultinrapidenhancementsinscientificandtechnologicalcapabilities.IFEisamulti-decadalendeavorandwillrequireinnovationtoenableaneconomicalenergysource.Thisisanopportunetimetomoveaggressivelytowarddevelopingfusionenergyastheworldpushestowarddecarbonizationtomitigatetheeffectsofclimatechange.Unlikeotherrenewableenergysources,IFEwouldbebothhigh-yieldandextremelyreliable,notsusceptibletovariablessuchastheweatherorextendedsupply-chains.FutureenergysourcessuchasIFEwillhelpmakethenationmorerobusttopotentialgeopoliticalcomplicationsandalleviateourdependencyonforeignenergyproviders.Therecent2020FESACLongRangeStrategicPlanendorsedthere-establishmentofanIFEprogramIhadthehonorofservingonthesubcommitteethatauthoredthe2020FESACLongRangeStrategicPlan“PoweringtheFuture:FusionandPlasmas.”3Thereportprovidesadecade-longvisionforthefieldoffusionenergyandplasmascienceandpresentsapathtoapromisingfutureofnewscientificdiscoveries,industrialapplications,and,ultimately,thedeliveryoffusionenergy.Theresearchcommunityworkedformorethanayeartodevelopawealthofcreativeideasdesignedtoacceleratefusionenergyandadvanceplasmascience,culminatinginaconsensusCommunityPlanningProcessReport.TheFESACreportdrewheavilyonthatreport,toidentifycriticalareasforresearchanddevelopmentandprioritizedinvestment.Amongtherecommendationswasto“strengthentheinnovativeandtransformativeresearchprogramelementsthatofferpromisingfutureopportunitiesforfusionenergycommercialization:stellarators,liquidmetalplasma-facingcomponents,IFE,andalternateconcepts…AnIFEprogramthatleveragesU.S.leadershipandcurrentinvestmentsshouldbetargeted.”Underthechargeforthereport,thecommitteewastodetermineaprioritizationofprojectsandresearchprogramsunderanumberofdifferentbudgetscenarios.Evenattheconstantlevelofeffortbudgetscenario(flatfundingrelativetoFY2019budgetlevels),thecommitteerecommendedsupportingamodestIFEprogram,focusedondevelopingenablingtechnologies,throughredirectionofexistingfunds.ThereturnoninvestmentwithevenjustmodestfundingforIFEissubstantial,acceleratingthefusionenergymissionandprovidingexcellentscience,andaidinginthedevelopmentofemergingtechnologiesandinnovativeR&D.Thisunderscoresthecommunity’scommitmenttothere-establishmentofarobustIFEprogramintheU.S.Withtherecentgame-changingresultsontheNationalIgnitionFacilitybringingustothethresholdofignition,andourdecadesofexpertiseininertialconfinementfusionscienceandtechnology,theU.S.iswell-poisedtomakesignificantadvancestowardaninertialfusionenergyfuture.IFEcanenablearoutetowardscleanandcommerciallyviablepoweraswellasunravelingmysteriesofplasmasinouruniverseanddevelopingtechnologieswithbroadsocietalimpacts.

3 Powering the Future: Fusion and Plasmas, A Report of the Fusion Energy Sciences Advisory Committee, U.S. Department of Energy, Office of Science, Fusion Energy Sciences (2020)