Chamber Materials Studies Thermal Conductivity of Foam Round

$Chamber Materials Studies Thermal Conductivity of Foam Round Robin Materials Refractory Armored Ferritic Helium$

Chamber Materials Studies Thermal Conductivity of Foam Round Robin Materials Refractory Armored Ferritic Helium Management L L Snead, G. R. Romanoski, J. Hunn, S. J. Zinkle (ORNL) J. Blanchard (UW) N. Ghoniem (UCLA) N. Parikh, S. Gilliam, S. Gudcumb (UNC) T van Veen, A. Fedorov (DELFT)

Thermal Conductivity of Tungsten Foam* K=a r Cp Diffusivity by thermal flash Cp = 0. 1329 J/Kg-K sample r, g/cc (%td) K W/m-K K/r measured K/r theoretical 1 1. 24 (6. 4%) 4. 8 3. 87 5. 6 2 1. 25 (6. 5%) 6. 7 5. 4 5. 6 3 1. 25 (6. 5%) 8. 1 6. 5 5. 6 *Source: Brian Williams of Ultramet via Sharafat. ~10% dense, 45 ppi.

Round Robin Materials Single Crystal Tungsten Polycrystalline Tungsten Chemically Vapor Deposited Tungsten

Round Robin Materials I think everyone is getting what they need ? ? ?

Primary Candidate First Wall Structure W/LAF Issues and development to address for archival publication Development of Armor Monolithic W Porous W Structure fabrication process and repair He management mech. & thermal fatigue testing Surface Roughening/Ablation Underlying Structure Liquid Metal Helium, or Salt Coolant? LAF(~600°C max) or ODS(~800°C) structure, possibly both. bonding (especially ODS) high cycle fatigue creep rupture Armor/Structure Thermomechanics design and armor thickness finite element modeling thermal fatigue and FCG Structure/Coolant Interface corrosion/mass transfer coating at high temperature? Modeling Irradiation Effects swelling and embrittlement

Development of W/LAF Development of Armor 2003 2004 2005 fabrication process and repair He management mech. & thermal fatigue testing Surface Roughening/Ablation Underlying Structure bonding (especially ODS) high cycle fatigue creep rupture Armor/Structure Thermomechanics design and armor thickness finite element modeling thermal fatigue and FCG Structure/Coolant Interface corrosion/mass transfer coating at high temperature? ? 2006 2007

Development of W/LAF Thermal Expansion Mismatch • Strain mismatch yields small compressive interfacial stress at IFE operating temperature

Fabrication Process : W/F 82 H • Two processes for bonding low activation ferritic to tungsten are being studied: Diffusion Bonding and Plasma Spray: I. Diffusion-bonded tungsten foil (. 1 mm thickness) - Allows the best possible mechanical properties and surface integrity - Tungsten will remain in the un-recrystallized state - No porosity II. Plasma-sprayed tungsten transition coatings - Allows for a graded transition structure by blending tungsten and steel powders in an intermediate layer to accommodate CTE mismatch. - Resulting microstructure is recrystallized but small grain size - May be spayed in vacuum or under a cover gas (wall repair) - Variable porosity

Thermal Fatigue Testing : Compare IR test to HAPL case Blanchard ANSYS runs · · HAPL : 154 MJ target, 6. 5 m chamber, 10 m. Torr Xe, 400 C coolant, 250 mm W IR : 20 MW/m 2, 10 Hz, 20 ms pulse, 100 C base, 3000 W/m 2 -K heat transfer coefficient Compare temperature distribution at time at which peak HAPL temperature occurs to distribution at end of IR pulse Next task is to compare interface stresses 300, 000 Watt Plasma Radiant Processing Facility

Temperature Distribution in Steel ORNL IR F 82 -H W F 82 -H Temperature (°C) W HAPL Depth (mm)

Thermal Fatigue Testing W coated specimen Cooling table Substrate material: F 82 H steel Coating material: tungsten (100µm-thick) Specimen size: 25 x 5 (mm) Rep rate: 10 Hz Max. flux: 20. 9 MW/m 2 (20 ms) Min. flux: 0. 5 MW/m 2(80 ms) Duration: 1000 cycles Substrate temp. (bottom): 600 ºC

Diffusion Bonded W/F 82 H After Fatigue Testing Diffusion Bonded As Deposited 1000 shot, 20 MW/m 2 Plasma Sprayed • No apparent degradation of adhesion of W to F 82 H following fatigue testing • For these fatigue tests, carbide dissolution indicating interface >900°C

Next Step : Tungsten Bonded Ferritic • Processing of a series of plasma sprayed F 82 -H underway at Plasma Processes, Inc. • Complete diffusion bonding development including thicker tungsten layers. • Complete modeling of IR coupling to tungsten samples, model interfacial stresses. • Carry out high-cycle thermal fatigue testing and mechanical testing.

Helium Management Overview (ORNL, Delft, UNC) Parametric Study FY-2003 Variables Materials FY-2004 Techniques Temp. FY-2005 Data Dose Single-X Irrad. Temp Total Dose Nuclear Reaction Analysis N He, % retention Poly-X Anneal Temp Dose Increment Thermal Desorption Diffusivity/Activation Energy TEM/SEM Defect size and distribution CVD, Foam Anneal Rate Modeling (MODEX Code) FY-2003 FY-2004 FY-2005 Generate defect dissociation and diffusion kinetics to model helium transport during thermal anneal Prototypic Irradiation Very high dose, Iterative Irradiation/Anneal. FY-2003 FY-2004 FY-2005

Helium Management (ORNL, Delft, UNC) Parametric Study Variables Materials Temp. Techniques Data Dose Single-X Irrad. Temp Total Dose Nuclear Reaction Analysis N He, % retention Poly-X Anneal Temp Dose Increment Thermal Desorption Diffusivity/Activation Energy CVD Anneal Rate TEM/SEM Defect size and distribution Foam Summary from last meeting: • weak dependence on material type • strong dependence on implantation temperature • annealing from 800 -2000°C diffuses significant helium ----> there are knobs to turn that delay exfoliation in W

Effect of Iterative Implant/Anneal on Retained Helium Automation of implantation/anneal system is now complete. A series of implantation to 1019 He/m 2 for 1, 100 and 1000 cycles has been completed 1. 3 Me. V He implantation Poly-X tungsten target Resistive Heating

Time (s) Helium Released Temperature (K) Counts/second Thermal Desorption Studies Temp (°K) • For room temperature implanted W, little difference in release between materials. • About half the helium is released by 2200 K, the maximum anneal used. • Gross release peaks were observed at ~1000, 1400 -1600, and 2000 K. • Activation energies are being calculated based on Arhennius curves of the helium release rate.

Next Step Modeling : Modified MODEX Code Defect energetic : RELAX Code being confirmed/adjusted experimentally Population /cm 3 Dissociation Energy (e. V) Damage and Ion Profiles : SRIM Implantation dose /cm 2 Number of Vacancies

MODEX Output Population /cm 3 Helium release from defect : Monte Carlo Diffusion of Helium : 1 -D Diffusion Annealing Temperature /K Free surfaces are input and helium recycling is calculated

Next Step for Helium Management • TDS studies will continue for 4 -6 months, this will generate enough data to benchmark MODEX input. • Effect of materials on retention and annealing is almost complete. Limited measurement and TEM are required. • Effect of rate of annealing on retained helium will be studied (late FY-04) • MODEX code to be upgraded and applied to IFE conditions. Benchmarked with experiment • Automated system is approaching a helium dose of IFE. --> 1000 cycles to 1019 /m 2 gives step implantations 5 -10 times IFE --> after reconfirming 1, 100, 1000 data, perform 10000 cycle implantation followed by TEM analysis to determine nature of stable helium complexes

Helium Release He/s Annealing Temperature /K