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 EffortAdvisory 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 DeathTritium retention(for graphite)Co-depositionSwelling and Lifetime

CrucialFatigue Properties Thermal conductivityRES (for graphite)

ProcrastinateDesign codesManufacturing large structuresDesigning 100% elevated temperature structureComposite architectural design

METS (Mapping Elevated Temperature Swelling) Experiment

Purpose : There is currently no high temperature irradiation data on the high quality graphitecomposites being considered for laser IFE. This program will yield data on swelling andthermal conductivity following neutron irradiation to high temperature and neutron fluence.

Materials : Kth(@RT) Kth(1000°C) (W/m-K) (W/m-K)

A) Mitsubishi Kasei MKC 1PH (unidirectional CFC) >700 ~250B) Fiber Material Inc. FMI-222 (balanced CFC) >450 ~220

Irradiation in HFIR Core Region Temperature Dose (°C) (dpa)

METS-1 Capsule 9 zones in range of 600-1500°C 2METS-2 Capsule “ 600-1500°C 4METS-3 Capsule “ 600-1500°C 10

Status:• All pre-irradiation measurements completed.• Capsules fabricated and awaiting irradiation in HFIR• Irradiation planned to begin this FY. Duration 1, 2 and ~7 months.• Post-irradiation examination to include thermal conductivity and swelling.

ORNL

OFES Swelling of CFC’s

Refractory Armored Materials

Critical Path Issues

Kiss of DeathMaterial developmentFatigue PropertiesExfoliation due to ionsIssues relating to structural material

CrucialThermal contact resistance and thermal conductivity Embrittlement (W grain growth, hydrogen effects, irradiation)In-situ or ex-situ repairDifferential thermal and irradiation expansion

ProcrastinateManufacturing large structuresTungsten 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

SiC

Refractory TitaniumRefractory powder

SiC 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 HzMaximum heat flux at maximum area : 5 MW/m2 at 2.5 x 35 cmMaximum heat flux attainable :12. 5 MW/m2 at 2.5 x 20 cm

SiC

10 ms, ? MW/m2 bursts

QuickTime™ and a decompressor

are needed to see this picture.

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 Eg>4 to 6 eV (UV cutoff <200-300 nm)

eliminates many promising candidates, including SiC, ZnO, TiO2, LiNbO3 and SrO (DPSSL and KRF); and MgO, ZrO2, Y2O3 and zircon (for KrF)

• Radiation effects literature reviewed for remaining candidates to select most promising candidates

Original List of Candidate Optical Materials (transparent at 200-500 nm)Oxides Nitrides Alkali halides

CaO, BaO, MgO, Al2O3, MgAl2O4, Y2O3, Y3Al5O12, Al23O27N5, ThO2, Li2O, LiAlO2, GeO2, CaWO4, BaTiO3, KNbO3, CaTiO3

AlN LiF, 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, Y2O3, ZrO2, ThO2, Li2O, LiAlO2, BaTiO3, KNbO3, CaTiO3, NaBr, KCl, KBr, RbCl, RbBr, RbI, BaF2

BaO, LiAlO2, KNbO3, CaTiO3, NaBr, KCl, KBr, RbCl, RbBr, RbI, BaF2

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/MgF2 bilayer, Sapphire and TiO2/MgAl2O4)

• 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.