Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Final Optic Fabrication, Testing and System Integration Mark Tillack, John Pulsifer, Joel Hollingsworth, S. S. Harilal With contributions from: Bill Goodman (Schafer Corp.), Hesham Khater (LLNL), Colin Ophus and Dave Mitlin (U. Alberta) HAPL Project Meeting San Diego, CA 8-9 August 2006 2 of 13 Progress was made in 5 areas 1. Improved our simulation capability • A KrF oscillator-amplifier configuration was installed and tested • Sample scanning and auto shutdown were added 2. Expanded the database on Al coatings (toward end-of-life) • More data were obtained on electroplated and e-coated mirrors 3. Developed techniques to fabricate larger optics • CMP was tested for post-processing large-area high-quality surfaces 4. Performed component and system integration • A substrate assessment was performed (Schafer) • Neutron irradiation experiments were planned 5. Explored alternative mirror concepts • 4” AlMo mirrors were fabricated in collaboration w/ LBNL and U. Alberta Control over beam characteristics required us to add an amplifier Death by 1000 cuts: loss of energy in the Pockels cell was the final straw polarize 3 of 13 “Performance improvements to the UCSD mirror test facility using an oscillator - amplifier configuration” S. S. Harilal, J. Pulsifer and M. S. Tillack 300 mJ Compex laser 150 mJ Gain curve with 5-ns pulse, 20.5 kV Compex, 17 kV LPX 150 mJ KD*P 50 mJ pulse slice “pseudo-ISI” 15 mJ 10 mJ 35 mJ LPX amplifier 200 mJ of polarized, smoothed, 5-ns light Performance is strongly dependent on HV and timing of both lasers (and Pockels cell) 4 of 13 Good news and bad news The good news: the gain curve results in profile smoothing The bad news: non-linear gain and jitter can distort the temporal profile Jitter allows leakage from latter part of seed Seed pulse High LPX voltage amplifies residual output from the Pockels cell 5 of 13 Facility improvements are making life easier, and higher shot-counts possible Automated shutdown enables higher PRF No damage Damage leading to shutdown External control of target position allows more data (better statistics) 6 of 13 We have a lot more data now on diamond-turned Alumiplate • Facility improvements have made data more reproducible • PRF data are looking promising • Higher shot count data look worse (this may be the limit for Alumiplate) reproducibility PRF effect lifetime “Laser-induced damage testing of metal mirrors: fluence-life data and surface analysis” J. Pulsifer, M. S. Tillack, J. Hollingsworth, L. Carlson 7 of 13 Grain size effects on pure Al are obscured by variations in fabrication techniques • Evaporative coating was attempted because smaller grains should result in a stronger surface (y = o ky/d1/2) • All surfaces were diamond-turned • Not all evaporative coatings have smaller grains, and the trend with grain size is not obvious • Better control of fabrication processes is essential for continuation of this work Schafer Alumiplate Bach CMP provides us a pathway to highquality, large-aperture metal mirrors 8 of 13 • Uses a corrosive slurry with carefully passivated surface • Significant advantages over SPDT: – Less “invasive” (thinner coatings) – Time depends on depth, not area – History of semiconductor-level QC Cabot Microelectronics is supporting this work with substantial IR&D support “Fabrication techniques for Al and Al alloy optical coatings for the GIMM” J. Hollingsworth, J. Pulsifer and M. S. Tillack <1 nm RMS, 15 nm pits A new alloy, AlMo was explored as a high-strength alternative to pure Al • • 2-gun magnetron sputtered • • Improved mechanical properties 9 of 13 Thick (>5 m) specular coating obtained with no postprocessing Reflectivity & conductivity? Amorphous/nanocrystalline regime Hall-Petch and solid solution hardening regime Acknowledgements: Thanks to Tim Renk, SNLA Velomir Radmilovic, LBNL Dave Mitlin, U. Alberta Colin Ophus, U. Alberta Al-16%Mo and Al-24%Mo were fabricated and tested • Beautiful, specular thick film • Low conductivity and increased absorption: poor performance 10 nm 100 nm 5 m Possible solution: Al capping layer gradient from AlMo to pure Al AlMo (16%) Si substrate tAl tgrad tAlMo 10 of 13 Candidate substrates were evaluated 11 of 13 in preparation for radiation testing (1 cm) and prototype (4”) development Candidates: Metrics: • Carbon Based • Neutronic feasibility • • • – C-C composite – Carbon fiber reinforced Silicon Carbide -SiC (polycrystalline) – Reaction bonded SiC (2-phase, polycrystalline) -SiC (CVD, polycrystalline) -SiC foam core (CVD/CVI, polycrystalline) Silicon – Silicon foam core (CVD/CVI, polycrystalline) – Czochralski (single crystal) Aluminum & Alloys – AlBeMet® 162 – Al 6061 foam “Candidate Mirror Technologies for the Grazing Incidence Metal Mirror” Bill Goodman (Schafer Corp.) • • – Neutron damage resistance – Purity Manufacturability – Surface figure – Roughness – Coating adhesion – Cooling capability Industrial capability – Available database – R&D needs (risk) – Cost 12 of 13 Neutron irradiations are being planned • A key issue for substrates is neutron-induced swelling • We plan to test candidate substrates: SiC, Si, AlBeMet, Al-6061 50 mm • Include Al coatings to measure neutron-induced roughness • Measure surface shape and roughness after irradiations Three 22-day cycles 5.4 FPY dose 8 mm Test optic • HFIR flux: >0.1 MeV: >1 MeV: • Power plant: >0.1 MeV: >1 MeV: 1015 n/cm2/s 6x1014 n/cm2/s ~1013 Handling of activated specimens is a major concern. We are performing activation and dose calculations prior to exposure, and will measure dose rates after exposure Al-6061 after full exposure n/cm2/s ~1013 n/cm2/s background level 13 of 13 Next-step goals for GIMM R&D • Coating-substrate development – Fabricate and test Al on C/Si and Al/Be composites – Continue efforts on coating improvements – Obtain 4” specimens from vendors – Plan test campaigns at Mercury and Electra • End-of-life testing – Complete the facility improvements – Perform further studies of rep-rate effects – Acquire data to 108 shots • Radiation damage testing – Finish planning – Obtain specimens