Tungsten Armor Engineering:

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• Tungsten Armor Engineering
• Debris Ions and He-Bubbles
• Carbon Implantation
• Roughening Mechanisms
• Shahram Sharafat, Nasr Ghoniem, Qiyang Hu, Jaafar
  El-Awady, Sauvik Benarjee, and Michael Andersen
• University of California Los Angeles, CA.

11th High Average Power Laser Program
WorkshopLawrence Livermore National
LaboratoryLivermore, CAJune 20-21, 2005
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TOPIC

• Debris Ions and Helium Bubbles
• Carbon Implantation
• Roughening Mechanisms

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Debris Ions and He-Bubbles
He-Implantation Experiments Ions - He plus D,
P (planned)
HAPL W-Armor Exposure Ions - He plus P, D, T,
C, Au, and Pt
Do we need to consider these in He implantation
experiments ?
- How much damage do they cause ?- What is
their effect on He-bubbles ?- Do we need to
modify experiments ?
Use the HEROS code to investigate
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Density Profiles (SRIM)
DEBRIS-IONS
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Low- and High Yield Target Debris- and Burn Ions
Based on THREAT SPECTRA Based on largest
percentage of ions
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Self-Damage (Defect) Rate Profiles (SRIM)
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Comparison of Damage Rates
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HEROS Damage and Implantation Profiles
SRIM Profiles
HEROS Input Profiles
Implantation Density
Burn
ImplantationDebris (apa/s)
Ion Self-Damage
Damage Debris (dpa/s)
Burn
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HEROS Bubble Concentration including Debris
Damage
Temperature Rise 2200 oC Chamber Radius
10.1 m 2 Consecutive Shots (5Hz)
Bubble Concentration in W (/cm3)
Green ? Annealing Temp. Drop Red ? Implantation
2 Consecutive Shots
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Bubble Concentration Including Debris Damage
Burn
T10-10sec
T10-8sec
T0.4?sec
T0.7?sec
Debris
Annealing
Effect of D, T, C, Au Simultaneous Self-Damage)
T1.5?sec
T2.1?sec
T0.8?sec
T0.8msec
High Temperature Annealing
End of Implantation
Annealing
Burn-2nd Pulse
Debris- 2nd Pulse
Annealing-2nd Pulse
T0.4sec
T0.2s0.7?s
T0.2s 2.1?s
T0.2sec
End of Pulse Two
End of Pulse One
End of Burn of Pulse Two
End of Debris of Pulse Two
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Importance of Simultaneous Debris-Ion Damage

• Large displacement damage is caused by Debris
  Ions (C, Au, P, D, T , Pt)
• Factor of 10 X He-Self Damage
• Results in SUPERSATURATION of vacancies
• Supersaturation of vacancies provides larger
  number of He-trap sites

Poster by Q. Hu on He-Modeling
Schematic of He-Bubble Resolution

• High Debris-Ion Damage Rates
• Momentum transfer of Excess Interstitials
• Collisional Displacement of He from bubbles
  Bubble RE-SOLUTION
• Increases effective DHe coef.
• Rapid temperature rise (2200 oC) facilitates
  annealing of He-Vac-Clusters and small Bubbles.
• Combination of high debris ion damage plus high
  temperature rise significantly enhances
  Helium-recycling

CollisionCascade (SIA)
HeliumBubble
Self-Interstitial W-atom Produced by Debris
(PKA)
Smaller Helium Bubbledecorated withHe-Vacancy
Clusters
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TOPIC

• Debris Ions and Helium Bubbles
• Carbon Implantation Mechanical Properties
  Helium Retention Tritium Retention
• Roughening Mechanisms

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Debris Carbon Implantation Profile (SRIM 2003)

• Assuming No Carbon Diffusion (154 MJ Target)

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Debris Carbon Implantation Profile (SRIM 2003)

• Assuming COMPLETE Carbon Diffusion (5 Hz 154 MJ
  Target)

This slide was not shown
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Debris Carbon Implantation Profile (SRIM 2003)

• Assuming COMPLETE Carbon Diffusion (10 Hz 154 MJ
  Target)

This slide was not shown
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Temperatures
Slide from Jakes Presentation HAPL NRL
2005 Additions/Modifications appear in RED
Carbon arrives (max implantation depth 1 um)

• 154 MJ
• 7 m
• 250 microns tungsten
• 3 mm steel

This slide was not shown
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Impact of WC-Layer Thermo-Mechanical Props.

• Above 940 oC various W-C compounds can form
  depending on temperature and molar ratios.
• Thermo-Mechanical Impact
• WC W2C Tmelting 2800 oC
• Tm of WC 600 oC less than W
• WC is a ceramic? more brittle
• WC effects crack behavior

Demetriou, Ghoniem, Lavine, Acta Materialia.
(2002)
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Impact of WC-Layer Helium Release

• Could not find helium release data for WC.
• At elevated temperatures He retention in SiC and
  B4C is low (implanted He E5 keV He1e18
  /m2-s Temp RT Hino-JNM-1999).
• U-Pu-Oxide fuels show significant fission product
  (gas) migration.
• Migration of Helium bubbles through WC needs to
  be verified experimentally.

T. Hino, JNM (1999)
Inoue, JNM (2004)
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Impact of Carbon Implantation Tritium Retention

• High T implantation 2x1017 T/m2 per shot
  for a R10.1 m chamber.
• Effects of Carbon on T retention at High
  Temperatures?

Irradiated tungsten at 653K with carbon
concentration as a parameter (1 keV 7 1024 H/m2
Ueda,2004.
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TOPIC

• Debris Ions and Helium Bubbles
• Carbon Implantation
• Roughening Failure Mechanisms Effect
  of Hydrogen

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TOPICS

• Roughening induced Failure Mechanisms

Surface Cracks in Polycrystalline Tungsten
Margevicius, 1999
Poster by J.El-Ewady on Bond-Strength Measurements
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Roughening Mechanisms Effect of Hydrogen

• About 4x1017 (TD)/m2 per shot for a 10.1 m
  chamber

• Cyclic heat load tests with a hydrogen beam and a
  comparable electron beam on CVD-tungsten.
• Hydrogen surface damage more severe than that by
  the electron beam.
• Cracked surface at all temperatures from 300 C to
  1600 C.

Experimental Setup of CVD Tungsten on Copper
H-Irradiation Conditions
Tamura, JNM, 2005
HAPL 3000 shots (10 min)
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TOPICS

• Effect of Hydrogen at 1600oC

Tamura, JNM, 2005
Surface morphology of the CVD Tungsten 110 shots
with a peak temperatures of 1600 C. Small pores
are observed at the coating surface (b) after
hydrogen beam irradiation.
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Summary and Conclusions

• DEBRIS ION Self-DAMAGE
• C-, Au-, and Pt Debris ions cause large damage
  within the first 2-um.
• Large damage assists in RE-SOUTION of helium
  bubbles
• - Facilitates efficient He-recycling.
• A high helium He-Recycling coefficient may be
  attainable.
• Needs experimental verification ?
• CARBON
• Implantation of C into W is significant
  Localized C/ W gt 1 in a few days
• Effects on mechanical performance of W-armor
  needs investigation.
• Effect of Carbon on P-, D-, and T retention has
  not been addressed.
• May be critical for W-armor reliability.
• ROUGHENING Mechanism of armor failure
  as it relates to roughening will be
  experimentally determined and theoretically
  modeled. Role of hydrogen implantation
  on surface cracking needs
  consideration.