Extrapolation of GDT Results to a DT Fusion Neutron Source for Fusion Materials Testing e
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Extrapolation of GDT Results to a DT Fusion Neutron Source for Fusion Materials Testing
eTom Simonen, U. Calif., Berkeley8th International Conference on Open Magnetic SystemsJuly 5-9, 2010 Novosibirsk, Russia
US Fusion Program (2010)
Establish the Scientific BasisBurning Plasma (ITER)Plasma Control (DIIID, EAST,KSTAR, JT60)Materials Science Plasma Material InteractionsNeutron Material Interactions..
US Mirror AssessmentStimulated by new Gamma-10 and GDT ResultsFormed a Mirror Study Group (Virtual Meetings)10 Institutions, 25 individualsHeld Two WorkshopsPhysics and TechnologyHeld a Magnetic-Mirror Mini-ConferenceAt 2009 American Phys. Society DPP MeetingParticipated in Numerous DOE Planning MeetingsProposed International CollaborationsRussia, Japan, ChinaTutorial Talk at 2010 APS MeetingDmitri Ryutov
ITER is under Construction China, EU, India, Korea, Japan, Russia, US(
FUSION CHALLENGES (Sci.Am., March 2010)Before fusion can be a viable energy source, scientists must overcome a number of problems.
Heat: Materials that face the reactions must withstand extremely high temperatures for years on end.
Structure: The high-energy neutrons coming from fusion reactions turn ordinary materials brittle.
Fuel: A fusion reactor will have to breed its own tritium in a complex series of reactions.
Reliability: Laser reactors produce only intermittent blasts; magnet based systems must maintain aplasma for weeks, not seconds.
Fusion Neutrons Damage Materials
Fusion Materials Must Withstand Neutron BombardmentThree Options toQualify Materials:Accelerator Based (coupons) Mirror Based (Blanket Sub-modules}Tokamak Based (Blanket Modules)
RTNS Accelerator Facility(US Rotating Target Neutron Source)
IFMIF Design by EU & Japan
Tokamak Component Test Facility (US Design)
Tokamak Fusion Nuclear Science Facility (US Design)
1980s Mirror Based Neutron Source Designs
Axisymmetric Magnetic MirrorGas Dynamic Trap (GDT) ConceptA.A. Ivanov, Fus. Sci. & Tech. 57, (2010), 320
GDT DD-Neutron Axial Profile(Agrees with Computer Simulation)
Electron Temperature vs Time(End Expansion = 100)*- H-plasma n 1.5 x 1013 cm-3 with H-NBI- H-plasma n 2.5 x 1013 cm-3 with H-NBI- D-plasma n 2.53 x 1013 cm-3 with H-NBI- H-plasma n 1.2 x 1013 cm-3 with H-NBI min gas puff- H-plasma n 3 x 1013 cm-3 with D-NBI- H-plasma n 3.53 x 1013 cm-3 with H-NBI
Neutron Flux Increases with Te(Now GDT Te = 0.25 keV so Flux = 0.4 MW/m2)(ITER Goal = 0.5 MW/m2, Fluence = 0.3 MW-yrs/m2)
A Russian Neutron Source DesignA MW of Fusion Power for Weeks
Neutron Flux ~ 2 MW/m2 Test Area ~ 1 m2I
A DTNS Showing Magnets, Shielding ,Neutral Beams, and Material Samples(Bobouch, Fusion Science & Tech. 41 (2002) p44)
With Todays GDT ElectronTemperature (0.25 keV)
DTNS Neutron Flux 80% of ITER
DTNS Neutron Fluence in One Year Exceeds that in ITERs LifetimeNote: DTNS does Not Address ITERs Burning Plasma Physics or Full-scale Blanket Module Testing
Design DTNS from GDT ResultsSame Physical SizeL, rHigher Mag. Field, NBI Energy and Power1.2 T, 80 keV, 40 MWSame Dimensionless ParametersBeta, B(z), L/ai, r/ai, Te/Ei
Same-Size & Dimensionless Scaling
GDTDTNSB, Tesla0.31.0Eb, keV2080Pb, MW530Beta (%)6060Mirror Ratio, R1717Length, & Radius, cm7 00 , 6700 , 6Radius / Gyro-radius22Debye Length, 10-3 cm22Te/Eb , %11Collisionality51 Marginalf(pe)/f(ci)60.6 More Microstablev(b)/v(Alfven)1.60.5 More Alfven Stab
A Possible Next Step
A Phased Approach (Physics >> PMI >> D-T Neutrons) B = 0.6 Tesla 1 s NBI 40 keV 1 MW 1 s
Key DTNS Scientific IssuesIncrease Electron TemperatureNow Te ~ 0.25 keV (0.4 MW/m2 neutrons)Demonstrate Te > 0.5 keV (80 keV NBI)Confirm MHD Stabilization PhysicsDiagnostics and SimulationEvaluate DTNS DesignSimultaneous Neutron and PMI Testing?
Key DTNS Technical IssuesHigh Neutral Beam Power Large Tritium Recycling
Consider Simple Tandem-Mirror Concept (GDT-SHIP concept)Small Axisymmetric End-Cells Reduce Plasma End LossesReduces overall neutral beam power Reduces Tritium Recycling
A Tandem-Mirror Neutron Source (TNS) (Based on TMX Data and the GDT-SHIP Concept)
TNS FeaturesPlug to Center-cell density ratio4To reduce end loss 4-foldPlug Mirror ratio3To reduce AIC and loss cone sizePlug NB injected at mirror ratio 1.3For AIC StabilityNeutral Beam Power (MW)20Half of DTNS
TNS ParametersMaximum Miagnetic Field, 20 TeslaPlug Mirror Ratio, 3Central-Cell Magnetic Field, 1.2 TeslaCentral-Cell NBI Power, 10 MWEnd-Cell NBI Power, 5 MW eachElectron Temperature, 2 keV
TNS Challenges(GDT-SHIP can address many issues)Electron TemperatureMHD Stability at Higher TeEnergetic Ion iMicro-stabilityTritium RetentionDetailed Modeling Needed
GDT SHIP can address many issues
SummaryA DT Neutron Source (DTNS) can have the same Physical-Size and the same Dimensionless -Size as GDTA Simple Tandem Mirror Neutron Source (TNS) Reduces Tritium Reprocessing 4-fold and Reduces the Neutral Beam Power 2-fold.
We Can Produce 1 MW of Fusion Power Sustained for Weeks within 10 Years
Purpose: Test materials & SubcomponentsDemonstrate sustained fusion power Features:Based on recent GDT ResultsLow Tritium Consumption,No tritium Breeding RequiredSimple Construction Geometry.