Transcript ppt

Update on ORNL Diagnostic and Tungsten
Armor Efforts
Keith Leonard, Glenn Romanoski, Lance Snead
Oak Ridge National Laboratory
Nalin Parikh
UNC, Chapel Hill
Shahram Sharafat
Out West
Presented at the HAPL Meeting
PPPL, Princeton, NJ
December 12-13, 2006
Carbon Buildup In W-Armor
Model Carbon diffusion with Temperature evolution (t=0 use spatial Carbon implantation
profile and “end of shot” temperature profile)
Carbon Implantation Profile
1.6E+19
R=10.1 m
1.4E+19
Carbon Concentration
7.E-07
6.E-07
5.E-07
1.0E+19
4.E-07
8.0E+18
3.E-07
6.0E+18
2.E-07
4.0E+18
1.E-07
2.0E+18
0.0E+00
0.E+00
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Implantation Depth (um)
1.2E+24
Carbon Concentration (1/m 3)
C/um
C per W (apa)
1.2E+19
C / W Atom Ratio (apa)
Carbon Conc.(#/um) .
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W = 6.34x1028 /m3
1.0E+24
R=10.1 m
405 MJ Target
100 Shots
50 Shots
30 Shots
20 Shots
10 Shots
1 Shot
Carbon Impl.
8.0E+23
6.0E+23
4.0E+23
2.0E+23
Within ~ 10 days of operation
C-concentration =
W-concentration
0.0E+00
0.0E+00
5.0E-07
1.0E-06
1.5E-06
Depth (m)
2.0E-06
2.5E-06
3.0E-06
Objectives for performing carbon ion
implantation in tungsten
• C ions (~ 0.5 MeV) will be implanted in W samples heated to IFE
surface-relevant temperatures (~2000C). Tungsten samples will
include two plasma sprayed tungsten materials and other
candidates used for He implantation.
• Models for carbon implantation will be validated and refined.
• Response of W to high-dose carbon implantation and tungsten
carbide formation will be assessed.
• Mobility of carbon through porous, plasma sprayed
microstructures will be quantified.
• Combined effect of C and He implantation will be assessed.
Development of VPS W/LAF
O
C
Interface
20.0keV
• We are considering the VPS W/LAF sufficiently
mature. Have withstood 10,000.
• Continuing long term aging of interface
(currently > 10,000hr)
• Next series of thermal fatigue tests planned for
long-term aged and carbon implanted material.
Tungsten
10.0kX
1.0 µm
W-Surface
W-F82H Interface
2.5mm below Interface
735
Temperature [oC]
F82H Steel
715
695
675
655
635
615
359
360
361
362
Time [s]
363
364
The flux of carbon ions into the W armor surface
ensures the formation of tungsten carbide
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The formation of W2C and WC is
likely to cause near surface
dilatation and spallation damage.
•
A tungsten carbide reaction zone
will likely affect He damage.
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Carbon ions near the surface are
a potential source of Carbon to
the W/FS interface.
Polycrystalline tungsten was implanted with carbon ions by UNC
at RT followed by annealing at 2000ºC for 5 min.
XRD analysis confirmed the formation of W2C
Under 1 micron
C dose: 1.4 E19 c/cm2 @ 100K eV
Carbon Implanted Tungsten
Step 1:
• Carbon implantation
• Polycrystalline W
• 1.4x1019 cm-2
• Room temperature
Implanted surface
Step 2:
• Thermal anneal
• Electrical resistance heating
• 2000ºC
• 5 minutes
Milling artifacts
from FIB
Grain #1
Grain #5
Cross-section from sample
milled out by focused-ion
beam (FIB) for TEM
examination.
Grain #3
Grain #4
Carbon Implanted Tungsten
Particles observed along
grain boundaries.
Implanted surface
• Discontinuous along
boundaries.
• Typically 100 to 200 nm in
size.
• Observed to a depth of 7.6 mm
from surface.
Milling artifacts
from FIB
Grain #1
Grain #5
Grain #3
Grain #4
Carbon Implanted Tungsten
Particles observed in grain
(#1) near implantation
Implanted surface
surface.
• Needle-like, consisting of
segments.
• Up to 2 mm long, 25 nm
thick.
• Observed to a depth of 2.6
mm from surface.
Milling artifacts
from FIB
Grain #1
Grain #5
Grain #3
Grain #4
Carbon Implanted Tungsten
Particles observed along
grain boundaries.
Implanted surface
• Discontinuous along
boundaries.
• Typically 100 to 200 nm in
size.
• Observed to a depth of 7.6 mm
from surface.
Milling artifacts
from FIB
Grain #1
Grain #5
Grain #3
Grain #4
Helium Implantation Studies of Simulated Irradiation
Damage to Aluminum Mirror Performance
Issue:
He implantation of aluminum mirrors is used as a first approach at
simulating the changes in optical properties and performance of mirrors in
the IFE under irradiation. The degree of surface roughening and the
resulting degradation in optical performance of metal mirrors for the IFE
as a result of charged particle implantation and neutrons is an important
issue that has not been well addressed.
Sample 1
1x1019 He/m2
0º tilt
1x1020 He/m2
0º tilt
1x1021 He/m2
30º tilt
1x1020 He/m
30º tilt
Material:
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1x1021 He/m2
0º tilt
1 inch diameter electrodeposited aluminum, 250 micron thick, on 6061-T6
aluminum substrate – manufactured by AlumiPlate Inc.
Diamond turned mirror surface, between 40 to 46 Å surface roughnessturned by II-VI Infrared.
1x1019 He/m2
30º tilt
He Implantation:
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Performed by Nalin Parikh and Shon Gilliam, UNC-Chapel Hill.
Use of beam mask allowing for multiple implantation tests per sample.
110 keV, 4He implantation.
1x1019, 1x1020 and 1x1021 He/cm2
0, 30 and 60º angle of incidence.
Room temperature implantation.
Implantations produce a range of damage from 0.01 to 2 dpa at 100 nm
below the surface for the various conditions based on SRIM code
simulation.
Sample 2
1x1021 He/m2
1x1020 He/m2
Current Status of Work:
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Samples received at ORNL for optical measurements.
Some discoloration on the surface for the 1021 He/cm2 locations.
Samples currently
– Optical ellipsometry techniques for changes in quality.
– Atomic Force Microscopy for changes in surface roughness.
– SEM examination of surface roughness.
1x1019 He/m2
All at 60º tilt
Update: Irradiation Damage on
Dielectric Mirror Performance
Dielectric Mirrors
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Films deposited by E-beam with ion-assist on sapphire substrates.
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Quarter wavelength bi-layers of HfO2 / SiO2, HfO2 / Al2O3 and Al2O3 / SiO2.
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Quarter wavelength monolayers of HfO2 (26.9 nm thick), Al2O3 (36.5 nm thick) and SiO2 (40.5
nm thick) on sapphire.
Tasks
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Phase 1, FY-06: He implantation
– Collaboration with Nalin Parikh (UNC)
– Tests conducted on monolayer films only to evaluate film/substrate interactions.
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Phase 2, FY-07: Neutron irradiation
– Collaboration with T. LaHecka (Penn. State) and M. McGeoch (Plex Corp.)
– Irradiation at High Flux Isotope Reactor and post irradiation evaluation at ORNL.
Changes to Monolayer Thin-Films
Following Helium Ion Implantation
Issue:
Multilayered dielectric mirrors could significantly improve
transmission of reflected electromagnetic energy, but little is
known about their longevity and performance in IFE relevant
environments. Preliminary work on performance of dielectric
mirrors under neutron irradiation has been inconclusive. This is
due in part to the behavior of the constituent film layers under
irradiation and the film/substrate interface interactions not being
understood.
He implantation
mask
Material:
E-beam / ion-assist deposited films of quarter wavelength thick:
• Al2O3 (36.5 nm thick) on sapphire
• SiO2 (40.5 nm thick) on sapphire
• HfO2 (26.9 nm thick) on sapphire
• Un-coated sapphire for control
He Implantation:
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Phase 1 of study (Phase 2,HFIR Neutron Irradiation).
Performed by Nalin Parikh and Shon Gilliam, UNC
Use of beam mask allows multiple implantation tests.
110 keV, 4He implantation, 0º tilt, room temperature.
1018, 1019, 1020 and 1021 He/m2.
Implantation conditions produce 0.001 to 1 dpa of damage at
the film/substrate interface – SRIM calculations.
Current Status of Work:
• General inspection of films by SEM showed no signs of
delamination or blistering.
• Atomic force microscopy carried out to determine
changes in surface roughness and step height
differences between implanted and non-implanted
regions.
• Optical examination by ellipsometry techniques for
changes in quality pending.
Changes to Monolayer Thin-Films
Following Helium Ion Implantation
• AFM data.
• SiO2 monolayer on sapphire.
• 1x1018 and 1x1019 He/m2 dose.
• No significant difference observed on film surface.
• Ellipsometry and high-resulution SEM underway
Nalin et al. has performed Carbon implantation on three polycrystalline
tungsten samples at ambient temperatures followed by annealing at 2000C
for 5 minutes. The samples include the following C+ Doses: I believe all are
100KeV implantation voltage. Nalin can confirm.
GM2 1.4E19 cm-2
GM3 3.6E17 cm-2
GM4 5.4E17 cm-2
X-ray diffraction confirms W2C formation in all samples. The diffraction
pattern attached for GM2 shows some shift from the perfect W2C lattice due
to non-stochiometry according to Burl Cavin (see phase diagram). Keith has
confirmed the presence of W2C in the GM2 sample.
Effects of Carbon Implantation (ORNL/UNC/UCLA)
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Issue: About 6.8x1019 per shot Carbon atoms are released from the 365 MJ Target (10 m Chamber):
– ~1.7 appm per shot Carbon in Tungsten  in about 1x106 shots C/ W ~ 1.7 (1.2 days @ 10 Hz)
– ~0.7 appm per shot Carbon in SiC
 in about 1x106 shots C/ W ~ 0.7 (1.2 days @ 10 Hz)
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Goals:
(1) Investigate the Behavior of Carbon Implantation :
– Free or bound Carbon (WC and W 2C) ?
– Release of Carbon from surface or Diffusion of Carbon toward W/Steel Interface ?
(2) Investigate Helium Release from Carbon Implanted Region :
– Helium release
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Experiments:
Follow Sample Handling Procedure
(1) UNC Carbon Implantation (Single-X W) Steady State followed by 1 Annealing Cycle:
• Implantation at T = 850°C, <0.5 MeV
• Total C-Fluence = 1.6x1022 C/m2 (eq. to ~3x105 shots or ~ ½ day at 10 Hz)  C/ W ~ 0.5
• Anneal at 2000°C for ~430 sec (total time above 1000 C for ~3x105 shots)
• Determine depth profile and density of Carbon & Perform Hardness measurements
(2) UNC Helium Implantation (use Carbon exposed SX-W). Step wise He followed by 2000 C annealing:
• Implant 1x1019 3He/m2 at 850°C, flash anneal at 2000°C in 1000 or 100 steps
• Determine Helium release and depth profile.
Modeling:
– Modify Carbon Diffusion model (UCLA) to include WC and W2C formation
– Add Carbon Implantation/Carbide Formation to the HEROS code He model (UCLA):
• Account for large damage rates caused during C-implantation and short time at T.