Transcript ppt
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