Chamber Materials - overview and plans OFES Supported Materials Research Fatigue thermomechanics (Ghoniem presentation) High temperature swelling of graphite fiber composite Critical issues from Chamber Materials Plan (HAPL) Transmissive Optics Formation and annealing of absorption centers Modeling of cascade and surviving defects in silica Reflective Optics Laser induced damage threshold Environmental effects (dust/debris) Modeling surface modification under repetitive pulsing Structural Materials Metallic structure - fatigue and pulsed irradiation effects Composite System - CFC lifetime Refractory Armored Composites - basic fabrication and performance Modeling - Defect formation and migration in graphite Safety Tritium retention in graphite

Materials Working Group Effort Advisory Group, including:Jake Blanchard (UW) Nasr Ghoniem (UCLA) Gene Lucas (UCSB) Lance Snead (ORNL) Steve Zinkle (ORNL) Transmissive Optics (Zinkle) Reflective Optics (Zinkle, Blanchard, Ghoniem) Structural Materials (Snead, Ghoniem, Blanchard, Lucas) Safety (Snead)

Critical Path Issues - Graphite Composite Kiss of Death Tritium retention(for graphite) Co-deposition Swelling and Lifetime Crucial Fatigue Properties Thermal conductivity RES (for graphite) Procrastinate Design codes Manufacturing large structures Designing 100% elevated temperature structure Composite architectural design

OFES Swelling of CFC’s

Refractory Armored Materials Critical Path Issues Kiss of Death Material development Fatigue Properties Exfoliation due to ions Issues relating to structural material Crucial Thermal contact resistance and thermal conductivity Embrittlement (W grain growth, hydrogen effects, irradiation) In-situ or ex-situ repair Differential thermal and irradiation expansion Procrastinate Manufacturing large structures Tungsten mobility/safety issues ???

Refractory Armored Composites Data mining completed - refractory armored graphite fiber composites appear hopeless for IFE - W - SiC system unstable ~ above 1200°C - Mo - SiC system unstable ~ above 1400°C Development program underway (ORNL) - Refractory : Tungsten (W-Re), Moly (Mo-Re, Mo-Zr-B) - SiC : CVD beta-SiC, Hot Pressed alpha-SiC, SiC/SiC Castellated surface modeling (Blanchard U.W.) SiC Refractory Titanium Refractory powder SiC Refractory powder First substrate castellation: 200  m deep x 200  m wide

Specifications:Argon plasma (up to 1MW) Pulse length : 10 ms (no shuttering) Rep Rate : 5-10 Hz Maximum heat flux at maximum area : 5 MW/m2 at 2.5 x 35 cm Maximum heat flux attainable :12. 5 MW/m2 at 2.5 x 20 cm SiC 10 ms, ? MW/m2 bursts 60 ms 5 MW/m2 Infrared Rapid Melt Processing and Thermal Shock

Discovery of Unprecedented Strength Properties in Iron Base Alloy Time to failure is increased by several orders of magnitude Potential for increasing the upper operating temperature of iron based alloys by ~200°C. Work being pursued by DOE OFES, DOE Fossil Energy, others IFE will explore grading of new W containing ferritics to W armor ODS ferritic

NRL IFE 2/2001 Input into Optics S.J. Zinkle, et al. HAPL IFE Program Workshop San Diego, April 4-5, 2002

Methodology for selecting candidate radiation-resistant transmissive optics Initial list of ~100 optical materials was screened to select materials with high transparency between 200 and 500 nm –Numerous optical materials rejected due to too low of band gap energy (e.g., carbides and most nitrides) Requirement of E g >4 to 6 eV (UV cutoff < nm) eliminates many promising candidates, including SiC, ZnO, TiO 2, LiNbO3 and SrO (DPSSL and KRF); and MgO, ZrO 2, Y 2 O 3 and zircon (for KrF) Radiation effects literature reviewed for remaining candidates to select most promising candidates

Original List of Candidate Optical Materials (transparent at nm) OxidesNitridesAlkali halides CaO, BaO, MgO, Al 2 O 3, MgAl 2 O 4, Y 2 O 3, Y 3 Al 5 O 12, Al 23 O 27 N 5, ThO 2, Li 2 O, LiAlO 2, GeO 2, CaWO 4, BaTiO 3, KNbO 3, CaTiO 3 AlNLiF, LiCl, NaF, NaCl, NaBr, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, MgF2, CaF2, SrF2, BaF2, RbMgF3, KMgF3, KZnF3, NaMgF3, LiBaF3

Candidate Radiation-resistant Optical Materials (no radiation-induced absorption peaks near 248 or 351 nm) KrF (248 nm)DPSSL (351 nm) CaO, BaO, Y 2 O 3, ZrO 2, ThO 2, Li 2 O, LiAlO 2, BaTiO 3, KNbO 3, CaTiO 3, NaBr, KCl, KBr, RbCl, RbBr, RbI, BaF 2 BaO, LiAlO 2, KNbO 3, CaTiO 3, NaBr, KCl, KBr, RbCl, RbBr, RbI, BaF 2 Alkali halides (NaBr, KCl, etc.) are less promising due sensitivity to radiolysis (displacement damage from ionizing radiation)

Dielectric Mirrors Previous work on irradiation damage in dielectric mirrors showed poor performance - LANSCE irradiation, ~100°C, many dpa - Layered silica structures, glassy substrates More radiation stable materials are being assembled for irradiation - Sapphire substrate - TiO2 (CTE 6.86 E-6) high-Z layer - Al2O3 ( CTE 6.65E-6) low Z layer - MgAl2O4 (CTE 6.97E-6) low Z layer

IFE Optics Irradiation Capsules to be irradiated to 0.001, 0.005, 0.01 and 0.05 dpa. Irradiation temperature tentatively 300°C Reflective optics for LIDT measurement supplied by Tillack (Aluminum, SiC, Molybdenum) Transmissive optics by Payne and Zinkle (KU-1 and Corning fused silica, oxides tbd based on white paper) Dielectrics by Snead and Payne (Sapphire sub. TiO2/MgF 2 bilayer, Sapphire and TiO 2 /MgAl 2 O 4 ) Samples to be shipped to LLNL following irradiation Status : Design work complete, safety documentation under review Capsule parts on order, samples on their way

Subwavelength Mirrors Subwavelength mirrors use periodic features of order /3 to /2 to form a surface waveguide which reflects light in a narrow waveband with very high reflectivity (as high as 99.9%). Higher reflectivity allows the use of smaller mirrors. Current research is for near-IR wavelengths. Near-UV wavelengths would simply require smaller feature size. Anti-reflectivity coatings can be used to protect the mirror surface. This technology is only in the development stage. Reflective Substrate Transparent Coating

Anti-reflective protective coatings Transparent anti-reflective coatings can be used to protect the surface of IFE mirrors. Mechanical damage to the anti-reflective coating from debris would not effect the reflective properties of the underlying mirror surface. Roughening of the anti-reflective coating is not necessarily detrimental to its operation. Radiation induced change to absorption in the coating would still be an issue, but the coating would be much thinner than a transmissive optic.