1. Background on GIMM studies in HAPL Challenges for a final optic optical requirements environmental threats system integration Design choices Logic pursued in Phase I Status materials development damage studies HAPL Web Conference, 15 Feb 2006 Slide 1

2. Early requirements were established in 2001 2 yrs lifetime @5 Hz = 3x10 8 shots 4-5 J/cm 2 normal to the beam 1% beam balance, 1% uniformity on target 20 µm aiming 80 nm ( /3) wavefront Later added: 5 nm rms, 25 nm PV 1% scattering Prometheus reactor layout Slide 2 These are subject to review and revision

3. Environmental threats are known Laser (5 mJ/cm 2 absorbed in 4 ns) X-rays (20-80 mJ/cm 2 @3-4 keV) Ions: diverted using B-fields Neutrons and gamma rays 5x10 12 n/cm 2 -s @14 MeV 10 13 n/cm 2 -s total Still ill-defined: Contaminants Vibration, mount stability Slide 3

4. Al @248 nm Al for UV reflectivity S-polarized 85˚ angle of incidence ~5000 GIMMlets The reference mirror concept consists of a stiff, light-weight (neutronically thin), radiation-resistant substrate with a thin metallic coating optimized for high reflectivity Slide 4 A GIMM was chosen for the perceived advantage of neutron damage resistance 248 nm

5. Slide 5 Phase I activities Coating development available Al mirrors do not meet requirements vendors engaged in R&D scalable, affordable technologies sought Laser damage testing emphasis on prototypicality 248 nm, beam smoothness, shot count, pulse length X-ray and ion analysis and testing (at LLNL) SiC and Al substrates not yet prototypical

6. Slide 6 Status of mirror development and testing Coating development 2 candidates: electroplating and evaporative coatings 50 µm thickness, 1–10 µm grains, 5 nm rms, 10 J/cm 2 @25 ns Readily available on Al alloy substrates LIDT testing New 100-Hz laser has excellent beam quality at the target and end-of-life testing capability. Pockels cell provides 5 ns pulses. X-ray and ion damage Analysis performed, ion irradiations performed, x-ray data pending Substrate development and component integration Need more effort on this – subject of this call