John Pulsifer, Mark TillackS. S. Harilal, Joel

Hollingsworth

GIMM experimental setup and tests at prototypical pulse

length

HAPL Project MeetingPrinceton, NJ

11-12 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

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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

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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.

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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 6x104 shots were accumulated for a fluence curve

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Long pulse, M109

Short 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 Tmax)

• Effect of cumulative damage? ∫ dt

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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.

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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)

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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)

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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

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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)

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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

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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

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Next-step goals for GIMM R&D15 of 16

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Questions?