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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

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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

Chamber Materials - overview and plans

slide2

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)

slide3

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

slide5

Critical Path Issues

Refractory Armored Materials

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

???

slide6

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.)

Refractory

powder

Titanium

Refractory

SiC

SiC

SiC

Refractory

powder

First substrate castellation:

200 mm deep x 200 mm wide

SiC

slide7

Infrared Rapid Melt Processing and Thermal Shock

5 MW/m2

60 ms

10 ms, ? MW/m2 bursts

SiC

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

discovery of unprecedented strength properties in iron base alloy
Discovery of Unprecedented Strength Properties in Iron Base Alloy

ODS ferritic

  • 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
input into optics

Input into Optics

S.J. Zinkle, et al.

HAPL IFE Program Workshop

San Diego, April 4-5, 2002

NRL IFE 2/2001

methodology for selecting candidate radiation resistant transmissive optics
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
slide12
Candidate Radiation-resistant Optical Materials (no radiation-induced absorption peaks near 248 or 351 nm)

Alkali halides (NaBr, KCl, etc.) are less promising due sensitivity to radiolysis (displacement damage from ionizing radiation)

slide13

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

slide14

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
  • Subwavelength mirrors use periodic features of order l/3 to l/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.

Transparent Coating

Reflective Substrate

anti reflective protective coatings
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.