John Pulsifer, Mark Tillack S. S. Harilal, Joel Hollingsworth GIMM experimental setup and tests at prototypical pulse length HAPL Project Meeting Princeton, NJ December 2006 With contributions from: Roman Salij (Cabot Microelectronics; Engineered Surface Finishes)

1.GIMM program logic 2.Review of front-end/amplifier facility upgrade 3.Short-pulse test results 4.More evidence of variability in optics 5.Efforts toward a thin film fabrication capability Overview 2 of 16

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Review of short-pulse setup using CompEX as front-end and LPX as amplifier Key challenges are timing and alignment. CompEX pulse is sliced to 4.5 ns 4 of 16

Nice profiles, but limited to 5 Hz pulse repetition freq to maintain energy stability System jitter increases with increasing PRF 5 Hz PRF limitation due to energy variation greater than 10% at higher PRF Amplified pulse shape (red) replicates the 4.5 ns seed pulse. Spatial profile of amplified beam is smooth. 5 of 16

Based on 1-D thermal diffusion, we previously applied a large safety factor with long-pulse testing Long pulse, M109 Predicted short-pulse result, M109 IFE goal Scaled goal Up to 6x10 4 shots were accumulated for a fluence curve 6 of 16

Long pulse, M109Short pulse, M109 Predicted short-pulse result, M109 Short-pulse test results exceeded our expectation The damage fluence is higher than expected from simple scaling One mirror was used for both 4.5-ns and 25-ns testing Damage does not scale like √pulselength (like T max ) Effect of cumulative damage? ∫  dt 7 of 16

Surface temperature effect; Time at temperature may also be a factor Absorbed heat flux using fixed total energy Surface temperature (2x energy in Compex) Short-pulse induced damage occurs at 30% less fluence, not 50% less as expected. 8 of 16

Our latest Alumiplated mirror (M109) performed extremely well (long pulse) Further evidence of variability in coating and surface finishing Long pulse, M109 Long pulse, M85 (previous best) 9 of 16

A quality coating with good diamond- turning provides much better damage resistance Alumiplate has not been a highly reproducible fabrication technique. Best is 3 nm RMS Roughness, 20 nm P-V Poor (m80) Good (m85)Best (m109) 10 of 16

CMP may offer a pathway to higher quality and better quality control 1 nm RMS Roughness 48 nm P-V Alumiplate mirror with Chemical-Mechanical Polish 11 of 16

CMP mirror damage resistance is comparable to previous Diamond-Turned mirrors Damage morphology of CMP is the same as D-T: grain motion in the coating Damage fluence curves (long-pulse) 12 of 16

We are developing in-house mirror fabrication capability at UCSD Thick, thin-film deposition at UCSD Nano3 facility (also externally at Thin Films, Inc.) Alloy development Post-processing (CMP, DT) to be done externally Sputter system at Nano3 facility, UCSD 13 of 16

Conclusions We have obtained data with 4.5 ns pulses Short-pulse damage resistance is better than we expected Time at temperature probably the reason Latest batch of Alumiplate seems to be capable of meeting the requirements for an IFE GIMM First CMP results were obtained and are promising. Next Steps: High cycle, alloys, substrates, large aperture 14 of 16

  Next-step goals for GIMM R&D 15 of 16

16 of 16 Questions?