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Chamber Materials Progress Round Robin Materials Refractory Armored Ferritic Helium Management

Chamber Materials Progress Round Robin Materials Refractory Armored Ferritic Helium Management J. Blanchard 1 , C. Blue, 5 A. Federov 2 , N. Ghoniem 3 , S. Gilliam 4 , S. Gidcumb 4 , J. D. Hunn 5 , S. O’Dell 6 , B. Patnaik 4 , N. Parikh 4 , G. R. Romanoski 5 ,

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Chamber Materials Progress Round Robin Materials Refractory Armored Ferritic Helium Management

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  1. Chamber Materials Progress Round Robin Materials Refractory Armored Ferritic Helium Management • J. Blanchard1, C. Blue,5 A. Federov2, N. Ghoniem3, S. Gilliam4, S. Gidcumb4, • J. D. Hunn5, S. O’Dell6, B. Patnaik4, N. Parikh4, G. R. Romanoski5, • S. Sharafat3, L. Snead5, T. Van Veen2 • Delft Institute2, ORNL5, PPI6, UCLA3, UW1, UNC4 • Presented at the High Average Laser Program Workshop • Georgia Institute of Technology • February 5-6, 2004

  2. Round Robin Materials I still think everyone is getting what they need

  3. Facility Improvements : Implantation/Anneal • Upper annealing temperature increased to 2500°C. • System now fully automated. Moving towards round-the-clock operation (8 x 104 irr/anneal/day)

  4. Facility Improvements : IR Thermal Fatigue • Facility has been used for interfacial fatigue of W/LAF • Previously 20 MW/m2 (time average), 20 msec pulse, 10 Hz, 10 cm2

  5. Facility Improvements : IR Thermal Fatigue • Now capable of 100 MW/m2 (time average), 2 msec pulse, 10 Hz, 5 cm2 • Phase 1 goal 1000 MW/m2 (time average), 0.1 msec pulse, 10 cm2

  6. Development of W/LAF : Phase 1 Effort and Milestones Development of Armor Fabrication process and repair He management Mech. & thermal fatigue testing “Engineered Structures” Ablation Underlying Structure bonding (especially ODS) high cycle fatigue creep rupture Armor/Structure Thermomechanics design and armor thickness detailed structural analysiis thermal fatigue and FCG Structure/Coolant Interface corrosion/mass transfer/coating 2003 2004 2005 2006 2007 scoping optimization scaling ! ! ! scoping & modeling optimization ! ! ! } ! ! !

  7. Phase I : Helium Management • Objective: To understand parameters controlling helium diffusion in tungsten to develop armor with near zero helium retention. • Approach: • Experimentally determine whether potential solutions exists. 04 Milestone. • Get diffusion coefficients of ideal materials for modeling. 04 Milestone • Define effect of microstructure, implantation, and anneal conditions, on retention of helium. • Carry out diffusion modeling and determine if “engineered” structures are required. 04 Milestone. • Phase I Goal : Perform long-term (>105 cycles, >1021 He/m2) IFE relevant implantation on candidate W/LAF ! ! !

  8. 1x1021 (He/m2) 2x1021 (He/m2) Spallation Problem 5x1021 (He/m2) 10x1021 (He/m2) 1.5 MeV He implanted polycrystalline W : 850C,flash annealed to 2000C.

  9. Comparison of Polycrystalline, Single Crystal, and CVD W (a) 850°C implant, as-implanted (b) 850°C implant, 2000°C anneal • At 5 x 1020 He/m2 single crystal, polycrystalline, and CVD tungsten exhibited comparable helium retention. • Before and after annealing the proton yields collected by NRA were the same within a few percent.

  10. Step ImplantationsWhat happens when we approach IFE implant/anneal cycle? A series of implantation to 1019 He/m2 for 1, 10, 100 and 1000 cycles has been completed for both single X and powder processed W. 1.3 MeV He implantation Poly-X tungsten target Resistive Heating

  11. Step ImplantationsWhat happens when we approach IFE implant/anneal cycle? • In both single and polycrystalline tungsten the helium dose per cycle affects retention significantly. • Single crystal releases helium more easily than polycrystalline. (b) (a) Proton spectra for polycrystalline (a) and single crystal (b)tungsten implanted at 850C and flash annealed at 2000C in 1, 10, 100, and 1000 cycles to reach a total dose of 1019 He/m2. The sample implanted with the total dose in one step was analyzed before and after the 2000C anneal.

  12. Single crystal annealed at 2500°C shows significantly less helium retention than the 2000°C anneal. Temperature plays a significant role when comparing the step sizes and the two different annealing temperatures. Effect of Annealing Temperature on Retention: Single-X W

  13. ! 04 Milestone : Go/No Go on helium management. Is there the potential to defeat the spallation problem? • Even though we have an extremely high fluence of helium, due to the small implant “packets” and the extreme annealing associated with the fusion event, difficult to diffuse helium clusters are not formed in single crystal W and the helium is released. We’re good to Go? • What is now needed: - Determine effective diffusivity needed for modeling. - Determine the annealing kinetics and carry out rapid implant/anneal experiments.(current experiments have long anneal) - Continue to define role of microstructure on retention. (as seen from the polyX W results, real structures may spall.) - Carry out high-cycle implantations (105 anneal/implantation) - Include effects of hydrogen. Where are we ???

  14. Phase I : Fabrication Process and RepairTungsten Armored Low Activation Ferritic Steel Objective: select and optimize methods for bonding tungsten to LAF steel and assess the integrity of these coatings under HAPL-relevant thermal fatigue conditions. Approach: • Evaluate methods for applying tungsten coatings to substrates. Fabricate and study adherence and thermal stability. Is there a viable material? FY-04 Milestone. • Given W thickness, model interface fatigue stresses and fatigue crack growth performance of underlying LAF. FY-04 Milestone. • Screen coupon coatings using thermal fatigue facility. Select candidate monolithic armor system or move to “engineered structure.” FY-05 Milestone. • Phase 1 Endpoint : Perform scaling studies and carry out prototype thermal fatigue at IFE relevant conditions: > 105 cycles, <100ms pulse width > 103 MW/m2 (during pulse) > 10 cm2 sample face ! ! !

  15. Viable W/Low Activation Ferritic?Screening material processing options. Processing Method Method of Screening Infrared fusion of tungsten powder Diffusion bonding of tungsten foil Vacuum plasma spraying powder Alternative approaches, e.g., CVD Thermal stability of interface Thermal Fatigue Interfacial Strength

  16. Viable W/Low Activation Ferritic?Screening material processing options. Processing Method Infrared fusion of tungsten powder Diffusion bonding of tungsten foil Vacuum plasma spraying powder Alternative approaches, e.g., CVD IR processing: 2350W/cm2(Flash: 6sec) • Initial runs showed promise, though somewhat non-uniform surface. Considered back-up.

  17. Viable W/Low Activation Ferritic?Screening material processing options. Processing Method Infrared fusion of tungsten powder Diffusion bonding of tungsten foil Vacuum plasma spraying powder Alternative approaches, e.g., CVD • Initial runs showed promise: high-thermal conductivity and good uniformity. Cracks were present due to CTE mismatch and phase change. Considered back-up.

  18. Vacuum Plasma Spraying of Tungsten Powders Preliminary VPS coating looked promising. An array of coatings were then ordered for evaluation VPS coatings were produced at Plasma Processes of Huntsville, Alabama

  19. As Sprayed VPS Tungsten on F82H Steel : Post-Spray Treatments Hot Isostatic Pressing • Post-spray hydrogen anneal at 800°C/4hrs provides stress relief. Annealing limited to 800°C due to steel substrate. Temps of 1700°C required for sintering VPS W coatings may be achieved with IR processing. • Post spray hot isostatic pressing 800°C / 35ksi achieved some densification of the coating (enhancing thermal conductivity.)

  20. Microstructural stability of F82H will limit the interface temperature to under 900C • Coarsening of carbides above 800C and dissolution around 900C will degrade mechanical properties. • The alpha – gamma - alpha phase transformation will impart large strains at the interface. • A critical thickness of tungsten will be required to dissipate the heat pulses to maintain the interface in an acceptable temperature regime. • Furnace cycling experiments will be performed to better understand interface stability.

  21. VPS coatings were produced with W/steel intermediate layer to minimize thermal strain mismatch. • Blended constituents will result in an average thermal expansion. • The intermediate layer is rather heterogeneous due to the coarse size of available steel powder. • Significant porosity will impart compliance to the coating (but reduce conductivity.)

  22. 04 Milestone : Go/No Go on tungsten armor. Is there a viable material? ! • All coating studied had promise. Vacuum plasma sprayed W on F82H low activation ferritic is being focused on. • Previous thermal fatigue showed promise. • Long-term stability of interface is still required, but it looks like a Go. Where are we ??? IR Thermal Fatigue Facility Rep rate: 10Hz, 1000 cycles Max. flux: 20.9MW/m2 (20ms) Min. flux: 0.5MW/m2(80ms) Substrate temp. (bottom): 600 ºC

  23. Questions ???

  24. Moving Towards Phase II Materials Development February 6, 2004 Georgia Institute of Technology

  25. Development of W/LAF : Phase 1 Effort and Milestones Development of Armor Fabrication process and repair He management Mech. & thermal fatigue testing “Engineered Structures” Ablation Underlying Structure bonding (especially ODS) high cycle fatigue creep rupture Armor/Structure Thermomechanics design and armor thickness detailed structural analysiis thermal fatigue and FCG Structure/Coolant Interface corrosion/mass transfer/coating 2003 2004 2005 2006 2007 scoping optimization scaling ! ! ! scoping & modeling optimization ! ! ! } ! ! !

  26. HAPL Program Plan

  27. • At the end of Phase 1 (constant dollars), assuming that a flat-plate or simple “engineered” armored structure appears workable, we will have materials ready for serious development. --there is a concern that significant time at the beginning of Phase 2 will be eaten optimizing a material, delaying the time consuming effort of property testing and proof testing. • At what point do we need irradiation data? There is fair data on LAF, but no data on its fatigue properties. The behavior of this tungsten, and the W/LAF interface is essentially not known. Can we wait until the end of Phase 2 for bad news here? • As we move towards Phase 2, the issue of fatigue will require seriously studied. High-cycle thermomechanical fatigue of prototype size component will be necessary. As this is very time consuming, any delay in delivery of the candidate armor will lengthen Phase 2. • Leading up to Phase 2 we should include in the MWG a specialist in design of vibrating structures and one on NDE. • Code qualifications may bite us. • Following Rene’s logic, we need qualified primary candidate at least two years prior to ETF. Is there enough time?

  28. Current Integrator (BPM) Controls sample temperature Power Controller Computer LabVIEW Controls implant dose Cup Control DAQ Card Sample Reads sample temperature Current Integrator (Faraday Cup) Infrared Thermometer Automation Hardware Schematic

  29. Thermal Fatigue Test Plan

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