Chamber Materials overview and plans

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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
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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)
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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 Des
ign codes Manufacturing large structures Designing
100 elevated temperature structure Composite
architectural design
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OFES Swelling of CFCs
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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 ???
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Refractory Armored Composites
Data mining completed - refractory armored
graphite fiber composites appear hopeless for
IFE - W - SiC system unstable above 1200C
- Mo - SiC system unstable above 1400C
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
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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
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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 200C. Work
  being pursued by DOE OFES, DOE Fossil Energy,
  others
• IFE will explore grading of new W containing
  ferritics to W armor

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Input into Optics

• S.J. Zinkle, et al.
• HAPL IFE Program Workshop
• San Diego, April 4-5, 2002

NRL IFE 2/2001
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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 Eggt4 to 6 eV (UV cutoff ?lt200-300
  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

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Original List of Candidate Optical Materials
(transparent at 200-500 nm)
12
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)
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Dielectric Mirrors
Previous work on irradiation damage in
dielectric mirrors showed poor performance -
LANSCE irradiation, 100C, 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
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IFE Optics Irradiation
Capsules to be irradiated to 0.001, 0.005,
0.01 and 0.05 dpa. Irradiation temperature
tentatively 300C 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
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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
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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.