1. Integrated Materials Plan Progress: Helium Blistering and Refractory Armored Materials Lance L Snead High Average Power Lasers Workshop December 6, 2002. Naval Research Laboratory BlisteringRAM’s Alexander Federov, DELFT Jake Blanchard, UCSB John Hunn, ORNLCraig Blue, ORNL Gene Lucas, UCSBTatsuya Hinoki, ORNL Nalin Parikh, UNCRene Raffray, UCSD Nao Hashimoto, ORNLSteve Zinkle, ORNL

2. Chambers Phase I Goals 1.Develop a viable first wall concept for a fusion power plant. 2.Produce a viable “point design” for a fusion power plant UCSD Wisconsin SNL ORNL LLNL UCSD Long term material issues are being resolved. Example- Ion exposures on RHEPP

3. Exfoliation of W Surface 5.5 x 5.5 mm implant area10x further magnification At the IFE flux of ~ 2x10 18 He/m 2 -s exfoliation will lead to the exfoliation of ~ 2cm/yr of tungsten in the absence of helium diffusion. The helium diffusion in tungsten is not well understood though will be a function of implantation temperature, annealing temperature, and microstructure. 10 22 He/m 2 -s 800°C implantation followed by 2000°C anneal

4. 3 He(d, p) 4 He “peak integration” 12 C(d, p) 13 C W target 1.3 MeV 3 He 12  m Mylar Detector 13 MeV p +, , backscattered D2 3 He profile Experiment Materials : Single Crystal (001) W Powder Met PolyX W CVD W Implantation : Step Implantation/Anneal Continuous Implantation/Anneal 2000°C Techniques ; Nuclear Reaction Analysis, TEM, Thermal Desorption, Surface Inspection Final Results: Mapping kinetics of He diffusion in W as a function of temp. and microstructure

5. 50°C Implant Single Crystal IFE dose ~ 10 17 /m 2 -shot Exp. Step = 2x10 17 /m 2 Anneal is 2000°C Repetitive dose/anneal exhibits less retained helium compared to a single dose followed by annealing (272 -vs- 582 counts.) --> Annealing helium before it forms immobile clusters will extend lifetime Effect of Stepwise Annealing

6. Effect of Microstructure 10 19 /m 2 at 800°C The tungsten microstructure has a strong influence on trapping of helium. In this case CVD has higher retention than polycrystalline (238-vs-82 counts) while single crystal had no measurable retained helium. Annealing to 2000°C did not reduce the retained He

7. Conclusion and Completion of Work There is a stong function of microstructure and implantation temperature on the helium diffusion in W at IFE-relevant helium implantation doses and temperature. By the correct choice of material it may be possible to avoid blistering. Future Work --> Map the retained helium and calculate diffusion coefficients as a function of implantation temperature. --> Determine microstructural features controlling trapping --> Use diffusion coefficients to model helium diffusion in IFE heat pulse --> Automate implantation target to carry out high-dose step-wise implantation/anneal ( 5x10 17 /m 2, 2000°C ) to 1x10 23 /m 2 --> 1 yr IFE fluence = ~ 10 25 /m 2

8. SiC Coating Procedure SiC (Hexoloy SA) Pretreatment* Brush or spray powder (W or Mo) IR processing SiC *Pretreatment: Ti vapor deposition W or Mo vapor deposition Anneal 72 hours (1300 or 1500ºC) Vapor deposited Ti Vapor deposited W or Mo Anneal W or Mo powder Plasma Arc Lamp coating Specimen size: 25×15×3 (mm) Lamp size used: 31.75×10 (mm) IR processing: uniform irradiance or scan Flash

9. Effect of IR Processing on Surface Roughness SiC without coating SiC W coating IR processing 10µm Interface Optical microscope (OM) images

10. SEM Images of W Coating Processed at 1828 W/cm 2 Scanning electron imageBack scattering (composition) electron image

11. EDS Mapping of W Coating SiC W coating W C Si Back scattering (composition) electron image EDS mapping of W, C, Si  W+CW+Si Hexoloy SiC + W (no pretreatment) Lamp power: 2350 W/cm 2 Scan speed: 9mm/sec

12. Effect of Vapor Deposited W and Pre-heating on Crack Propagation into SiC 10µm SiC W coating 2350W/cm 2 (3sec) 522W/cm 2 (20sec)+2350W/cm 2 (3sec) VD W+2350W/cm 2 (3sec)

13. SEM Images of W coating on SiC Scanning electron imageBack scattering (composition) electron image With pre-heating 522W/cm 2 (20sec) + 2350W/cm 2 (3sec) SiC W coating W+C SiC Si+W

14. Effect of Processing Condition on Flexural Strength of W Coated SiC W coating side Four point flexural test Specimen size: 50x4x3 mm Support span: 40 mm Loading span: 20 mm Crosshead speed: 10um/sec Substrate strength  W coating was not peeled off during flexural test  Strength of substrate SiC was decreased by IR processing  Vapor deposition prior to powder coating prevented degradation of strength

15. Tungsten on Reduced Activation Ferritic Melt Zone Tungsten Base Metal

16. OM Images on Ferritic Steel IR processing: 2350W/cm 2 (scan: 7mm/sec) Near edge

17. OM Images on Ferritic Steel IR processing: 2350W/cm 2 (scan: 6mm/sec)

18. OM Images on Ferritic Steel IR processing: 2350W/cm 2 (Flash: 6sec)

19. OM Images on Ferritic Steel IR processing: 2350W/cm 2 (Flash: 6sec)

20. Concuding Remarks and Future Work Refractory armored SiC has been produced with strength considerably higher than conventional techniques (CVD, PVD, etc.) Composite armoring to follow. Additional development including repeated layering may be required to make transition to 100% W surface. Ongoing work includes strength, fatigue, and thermal shock using IR processing facility. Initial attempt to armor ferritic steel was of limited success. Additional development work to reduce the melt/recrystallized zone will be carried out.

21. 300,000 Watt Plasma Radiant Processing Facility