Threats to the GIMM and Use of XAPPER for Testing

Jeff LatkowskiRyan Abbott

February 15, 2006

The GIMM run shows that while the temperature response may seem reasonable, stresses will could be significant

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• Compressive surface stresses could cause the optic to yield in compression and pose a fatigue or cracking threat

• The laser pulse will generate the greatest temperature spike with a magnitude of ~ 30 degrees

With a fluence of only 22.4 mJ/cm2, XAPPER canreplicate the expected peak temperatures and stresses

• Ironically, XAPPER operation will produce significantly longer time at temperature and stress than the actual IFE case

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We are completing ray tracing to designa new ellipsoidal optic for use on XAPPER

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Current optic ~1 J/cm2

New optic ~0.04 J/cm2

With ~10 mJ per pulse, could have spot radius of 2-3 mm instead of usual 500 m

Exposure will still be ~normal to surface (e.g., no grazing angle)

Proposed schedule:- final design by end of February- start mandrel in March- first new optic in June