2. M. S. Tillack, J. E. Pulsifer, K. Sequoia Final Optic Research – Progress and Plans HAPL Project Meeting, Georgia Tech 5–6 February 2004

3. Overview 1.Expanded database on electoplated Al 2.Mechanical and optical improvements 3.Near-term plans –Scale-up –Distribution of samples –Efforts to improve mirror quality –Gasdynamic modeling –Integration

4. 5-yr plan and progress to date 200120022003200420052006 startKrFtoday initial promising results at 532 nm attempts at thin film optics Phase I evaluation lower limits at 248 nm, chemistry control electroplate success

5. Percent Completion Phase I – February 2004 A. Quantify the threats (LIDT, x-ray, ion, neutron/gamma) B. Develop mitigation techniques C. Fabrication and integration (tasks extracted from Dec. 11, 2002 3-yr final optic plan)

6. Testing of electroplated Al continues

7. Ideally, fluence limits would be purely thermomechanical in nature Metals under primary stress usually follow a power law fatigue behavior

8. Our data doesn’t fit a power law very well 2 J/cm 2

9. R 2 =0.9992 if we use a simple log fit

10. Damage morphology: moderate fluence At 18.3 J/cm 2 laser fluence:  Grain boundaries appear to be separating  Damage is still “gradual” at 18.3 J/cm 2

11. Damage morphology: high fluence At 33 J/cm 2 laser fluence:  Rapid onset (2 shots)  Severe damage (melting)  probably starts with grains

12. Do we shoot for years, buy a kHz laser, or perform accelerated testing? Palmgren-Miner rule: damage accumulated at different stresses is additive n i = number of cycles at stress level i N i = fatigue limit at stress level i

13. Precipitation hardening could extend the damage threshold 20 J/cm 2

14. Key questions for nano-precipitate hardened alloys Will scattering and absorption be acceptable with a small percentage of nano-scale 2nd phase material?  optical modeling of absoprtion and scattering Will the yield strength be improved under the constraints of particle size and fraction?  mechanical modeling Will something else go wrong?  experimental demonstration is needed (misfit)

15. Beam quality with incipient damage If incipient damage does not exceed the 1% beam perturbation criterion, then mirror damage occurs first (y scan)

16. 5-yr plan 200120022003200420052006 starttoday 1. scale-up & testing 4. system definition improvements (material & optical) 2. irradiation testing (LLNL) 3. mitigation studies Phase I evaluation

17. FY04 plans: (1) Scale up Intermediate step between present (1-2”) and final (50-100 cm) optic sizes Fabricate mirrors for testing on HAPL lasers (100-500 J, 5-10 Hz) Increased attention to surface figure as well as microstructure morphology Near-term plan: –fabricate larger versions of Al on Al-6061 –with Schafer, procure Al on SiC mirrors –test on Electra this summer –test on Mercury

18. FY04 plans: (2) Sample distribution Radiation damage tests should use the reference optic –Al on Al-6061 can be obtained in 2-4 weeks (discussions with Alumiplate and ii-vi are underway) –Al on SiC tests should wait for validation We need protocols for characterization and testing Whoever needs optics, let’s talk.

19. FY04 plans: (3) Gasdynamic Modeling Contamination transport from the chamber to the optic –use computed velocity fields to track the motion of an embedded particle Chamber response to gas puffing –include a small blob of high-pressure chamber gas at the optic immediately preceding target yield

20. FY04 plans: (4) Integration Define the optical system in enough detail to deter- mine whether there are issues requiring R&D, e.g., –Develop the target/driver interface further (w/ GA) –Specify the beam steering and wavefront control methods ( e.g., where will these be achieved?) –Cooling and other mechanical design issues Define the design requirements and reference parameters in greater detail –Design lifetime: 10 8 shots –Operating temperature: 30˚C –Reflected beam smoothness: 1% (could tolerate more?) Need to organize the “final optic working group”

21. Final Optic Working Group

22. FY 2001|FY 2002|FY 2003 |FY 2004|FY2005 FY 2001|FY 2002|FY 2003 |FY 2004|FY2005 Original Final Optics Program Plan Scoping Tests: Irradiation & PIE (incl. annealing) Extended testing of prime candidates CONTAMINATION THREATS ModelingTest simulated contaminants ION SPUTTERING Calculate sputtering, gas attenuation X-RAY ABLATION Scoping tests (laser-based x-ray source) Damage modeling LIDT scoping tests for GIMM, materials development Mitigation Laser damage modeling, 3  data from NIF Modeling Mitigation RADIATION DAMAGE (neutron and gamma effects ) System Integration LASER-INDUCED DAMAGE