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Title: Government Labs

IFE First Wall Survival Development and Testing
of an Armored Ferritic L L Snead, G. R.
Romanoski, C. A. Blue, and J. Blanchard
  • Government Labs
  • NRL
  • LLNL
  • SNL
  • LANL
  • ORNL
  • PPPL
  • Universities
  • UCSD
  • Wisconsin
  • Georgia Tech
  • UCLA
  • U Rochester
  • PPPL
  • UC Santa Barbara
  • UNC
  • Industry
  • General Atomics

Presented at the 16th TOFE, Madison Wisconsin
September 16, 2004
HAPL IFE First Wall Materials
Carbon and refractory metals (tungsten)
considered - Reasonably high thermal
conductivity at high temperature (100-200
W/m-K) - Sublimation temperature of carbon
3370C - Melting point of tungsten 3410C
In addition, possibility of an engineered
surface to provide better accommodation of high
energy deposition is considered - tungsten
coated ferritic or SiC - carbon brush
structures - tungsten foam
Unique Threats to IFE First Wall
Intense cyclic heating - stresses and
sublimation due to pulse heating (Renk talk this
session) - cyclic stress induced debonding -
long-tem thermal stability Surface removal
due to high energy ions.
Temporal Distribution of Heat Flux
Instantaneous Heat Flux 10 MW/m2 (MFE) 104
MW/m2 (IFE)
Effect of Heat Flux on W-Armor Coated SiC
Raffray data
0 1 2 3 4 5 6
7 8 9 10
Time (microseconds)
Fabrication Process W/F82H
  • Two processes for bonding low activation
    ferritic to tungsten are considered
  • Diffusion Bonding and Plasma Spray
  • I. Diffusion-bonded tungsten foil (.1 mm
  • - Allows the best possible mechanical
  • and surface integrity
  • - Tungsten will remain in the
    un-recrystallized state
  • - No porosity
  • --gt Plates of W/Fe (ORNL) have
  • been produced and are being tested.
  • II. Plasma-sprayed tungsten transition coatings
  • - Allows for a graded transition
    structure by blending
  • tungsten and steel powders in an
    intermediate layer
  • to accommodate CTE mismatch.
  • - Resulting microstructure is
    recrystallized but small grain size
  • - May be spayed in vacuum or under a
    cover gas (wall repair)
  • - Variable porosity

Testing of Armored Ferritic W/F82H
The primary concern for armored materials is
the survival of the interface --gt CTE
mismatch produced during processing --gt
Stressed induced during pulsed heating --gt
Stability of a ductile interfacial region on
long-term annealing
Specimen Expansion (ppm)
Temperature (C)
High Density Infrared (HDI) Plasma Arc Lamp
  • Unique high density infrared plasma arc lamp
  • Most powerful radiant arc lamp in the world
  • Broad area processing with high radiant energies
  • Conservative heating rates
  • 2,000?C/s to 20,000?C/s
  • Allows controlled diffusion
  • on nanometer scale
  • Able to melt Rhenium
  • Melting point of 3180?C

Thermal Fatigue Testing
W coated specimen
Cooling table
Rep rate 10Hz Max. flux 20.9MW/m2 (20ms) Min.
flux 0.5MW/m2(80ms) Duration 1000
cycles Substrate temp. (bottom) 600 ºC
Substrate material F82H steel Coating material
tungsten (100µm-thick) Specimen size 25 x 25 x 5
Thermal Fatigue Testing
  • IR testing closely matches stress state at
  • Flexural tests will be performed on samples that
    incorporate the W armor and substrate to quantify
    the mechanical strength of the interface at
    different cycle durations and following thermal

Stress (MPa)
Blachard results
Depth (mm)
Thermal Fatigue Testing
W coated specimen
Cooling table
Rep rate 10Hz Max. flux 20.9MW/m2 (20ms) Min.
flux 0.5MW/m2(80ms) Duration 1000
cycles Substrate temp. (bottom) 600 ºC
Substrate material F82H steel Coating material
tungsten (100µm-thick) Specimen size 25 x 25 x 5
W Coated F82H After Thermal Fatigue Testing
Diffusion Bonded
As Deposited
1000 shot, 20 MW/m2
Plasma Sprayed
No obvious degradation of adhesion of W to
F82H following fatigue testing For these
fatigue tests, carbide dissolution indicating
interface gt900C
W Coated F82H After 10,000 Cycle Fatigue Testing
  • In interface over-temperature (gt900C) a W-Fe
    intermetallic forms.
  • Formation of W-Fe brittle phase will likely lead
    to interface fracture and coating failure.
  • Isothermal aging experiments will be performed on
    W / F82H samples to demonstrate the temperature
    and time limitations of the interface.

F82H Steel
Thermal Fatigue Facility Upgrades for Prototype
Testing (complete 2005)
Continuous operation 1 msec, 5 Hz at 100
MW/m2 300 cm2 surface area irradiation
Front surface temperature monitoring
Fabrication of cooled prototype plasma spray
tungsten armored low-activation ferritic
Helium Management
At room temp. growth of He bubbles beneath the
surface causes blistering at 3 x 1021/m2 and
surface exfoliation at 1022/m2. For IFE power
plant, MeV He dose gtgtgt 1022/m2 .

First Wall Armor
MeV Helium
MeV Helium
0 1 2 3 4 5 6
7 8 9 10
Time of microseconds
Effect of Iterative Implant/Anneal on Retained
A series of implantation to 1019 He/m2 for 1,
10, 100 and 1000 cycles has been completed
1.3 MeV He implantation Poly-X tungsten
target Resistive Heating
Effect of Iterative Implant/Anneal on Retained
Implantation to 1019 He/m2 for 1, 10, 100 and
1000 cycles
1.3 MeV He implantation Poly-X tungsten
target Resistive Heating
Determination of critical step size
Total 3He dose (1019 He/m2) Proton Yield (?10)
1 10
2 13
3 70
5 2000
10 7100
  • For Single-X W critical step size 31016
  • Helium doses implanted at 850C and
    flash-annealed at 2000C in 1000 cycles

Update on Effect of Peak Annealing Temperature
Single x annealed at 2500C shows
significantly less He retention than 2000C
anneal. Annealing temperature plays a
significant role in retained He and critical
dose. As part of the chambers study we need to
make precise assessment of implantation and
annealing temperatures to focus experiment.
Concluding Remarks
  • The HAPL program has selected refractory
    armored low-activation
  • ferritic steel as its prime candidate first
  • Currently, optimization of the plasma-sprayed
    W/F82H steel in near
  • completion and mechanical testing underway.
  • IFE-unique critical-issues are being pursued
  • - X-ray and ion ablation and roughening (Renk
    and Latkowski)
  • - thermal fatigue of tungsten ferritic
  • - long-term thermal stability
  • - helium management
  • Special issue of Journal of Nuclear Materials on
    subject of
  • HAPL chamber currently being assembled.

Fabrication Process W/SiC
SiC without coating
IR processing
Tungsten Powder
W coating
SiC was removed by sublimation of the surface of
the SiC prior to ordering the W powder melt.
Rough interface was formed.
The Path to Develop Laser Fusion Energy
  • Scalable Technologies
  • Krypton fluoride laser
  • Diode pumped solid state laser
  • Target fabrication injection
  • Final optics
  • Chambers materials/design

Phase I Basic fusion science technology 1999-
  • Target Design Physics
  • 2D/3D simulations
  • 1-30 kJ laser-target expts

Phase II Validate science technology 2006 - 2014
  • Full Scale Components
  • Power plant laser beamline
  • Target fab/injection facility
  • Power Plant design
  • Ignition Physics Validation
  • MJ target implosions
  • Calibrated 3D simulations

? Full size laser 2.4 MJ, 60 laser lines ?
Optimize targets for high yield ? Develop
materials and components. ? ? 300-700 MW net
electricity ? Resolve basic issues by 2028
Phase III Engineering Test Facility operating ?
Chamber Progress -1 Operating windowsEstablishing
Chamber operating windows is a
multidisciplinary, simulation intensive,
process...........Here is an example for a 154
MJ target.
UCSD Wisconsin LLNL GA
Summary of Thermal Fatigue Experiment
  • Thermal fatigue experiments were carried out
    successfully using IR processing facility.
    Preliminary results showed tungsten coating was
    stable following the heat load (10Hz, 23.5MW/m2
    (10ms), 1000cycles).

Candidate First Wall Structure W/LAF (W/SiC
Development of Armor fabrication process and
repair He management mech. thermal fatigue
testing Surface Roughening/Ablation Underlying
Structure bonding (especially ODS) high cycle
fatigue creep rupture Armor/Structure
Thermomechanics design and armor thickness finite
element modeling thermal fatigue and
FCG Structure/Coolant Interface corrosion/mass
transfer coating at high temperature? Modeling
Irradiation Effects swelling and embrittlement
Porous W Structure
Monolithic W
Liquid Metal Helium,or Salt Coolant?
LAF(600C max) or ODS(800C) structure,
possibly both.
Helium Management (ORNL, Delft, UNC)
Parametric Study Variables


Materials Temp. Dose
Single-X Irrad. Temp Total Dose Nuclear
Reaction Analysis N He,
retention Poly-X Anneal Temp Dose
Increment Thermal Desorption
Diffusivity/Activation Energy CVD Anneal
Rate TEM/SEM Defect size and
distribution Foam
weak dependence on material type
strong dependence on implantation temperature
annealing from 800-2000C diffuses
significant helium ----gt there are knobs to
turn that delay exfoliation in W