MWG Recommendation on HAPL Materials Work Going Forward

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MWG Recommendation on HAPL Materials Work Going
Forward
A MWG meeting held at UCLA May 15,16 2006 to
better coordinate modeling and experimental work.
The following includes specifics related to the
ORNL contribution to this work.
MWG Members Additional Meeting Presenters Jake
Blanchard Tim Renk Nasr Ghoniem Farrokh
Najmabadi Lance Snead Nalin Parikh Brian
Wirth Shahram Sharafat Steve Zinkle Jeff
Latkowski Jerry Kulcinski Stas
Gulobov Q Hu M Anderson L Schmitz
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Surface Thermomechanics
Goal Common experimental plan for all
irradiation facilities Experimental Controls
Follow Guidance for Handling and Testing of
Tungsten Common sample size (20x20 or 20x10
mm) Measurements Standardized and Applied
Surface Morphology Roughness (peak to
valley and characteristic wavelength) Crack
Density (surface electrical resistivity, TEM)
Mass Loss  Key question Do mass loss and
surface roughness/topology saturate with
fluence?
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Handling of Tungsten

• Cleaning Prior to experiments the tungsten
  should be soaked in an ultrasonic bath of
  research grade acetone for about ten minutes.
  The acetone bath should be immediately followed
  by an ultrasonic bath of ethanol (five minutes.)
  The samples should be covered and air dried.
  Prior to use samples should be blown clean with
  compressed air or other moisture-free gas.
• Do not use cotton, kleenex or q-tips to dry the
  surface. Cotton in particular is bad for surface
  scratching.
• Samples should be baked out prior to testing.
  Typically, 200C for 30 minutes is fine. Do not
  allow tungsten to be heated in vacuum poorer than
  10-4 Torr. For experiments that are actively
  heated this can be the first step.
• Foam samples must be thoroughly outgassed prior
  to testing and preferably stored in a desiccator.
• Testing of tungsten should be carried out in as
  high a vacuum as possible. Greater than 10-4
  Torr is required. If testing can not be carried
  out in the 10-6 Torr range then moisture and
  oxygen sensors are required.
• Samples must be firmly attached to heat sink with
  refractory materials (I.e. TZM moly mask and bolt
  arrangement.)

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IR Thermal Fatigue (ORNL)

• Exposure of single crystal tungsten following
  sample handling procedure to determine level of
  atmospheric pick-up.
• Base temperature of 600C.
• Verify interface temperatures.
• Complete upgrade to continuous operation.
• Carry out thermal fatigue of carbon implanted
  VPS materials.

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Update IR Thermal Fatigue (ORNL)
Specimen Size (cm2) Specimen Size (cm2)
300kW Upgrade 10
300kW Current 10
750kW Current 300
Software for continuous operation being
installed. Very high cycle testing of VPS
W/LAF on hold.
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Development of VPS W/LAF
O
C
Interface
F82H Steel
Tungsten
10.0kX
20.0keV
1.0 µm
We are considering the VPS W/LAF sufficiently
mature. Have withstood 10,000.
Continuing long term aging of interface
(currently gt 10,000hr) Next series of thermal
fatigue tests planned for long-term aged and
carbon implanted material.
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PETS (Pulsed Electron Test Stand) ORNL
Electron beam system currently under development
by HeatWave Labs, Inc.

• Pulse Width 0.5 to 1.5 µsec (variable)
• Pulse Rise/Fall Time 800 ns
• E-beam Voltage 70 kV
• Peak Current 75.6 Amps
• Pulse Frequency 100 Hz
• Duration gt 10 million shots
• Gun Perveance 4 µperv
• Beam Radius 0.36 cm (0.4 cm2)
• Current Density Variation 31
• ORNL responsible for sample holder
• and coolant design completed 5/06

Scheduled to be delivered to ORNL November
2006 Acceptance Testing On Site
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Update Thermal Model of E-beam Source
Preliminary model predicts moderate bulk
temperatures, extreme surface temperatures
Maximum surface temperature profile mimics 31
variation in e-beam power.
Beam optics by HeatWave Labs
Steady State Model
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Effects of Carbon Implantation (ORNL/UNC/UCLA)

• 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 _at_ 10 Hz)
• 0.7 appm per shot Carbon in SiC ? in about
  1x106 shots C/ W 0.7 (1.2 days _at_ 10 Hz)
• Goals (1) Investigate the Behavior of Carbon
  Implantation
• Free or bound Carbon (WC and W2C) ?
• Release of Carbon from surface or Diffusion of
  Carbon toward W/Steel Interface ?
• (2) Investigate Helium Release from Carbon
  Implanted Region
• Helium release
• Experiments Follow Sample Handling Procedure
• (1) UNC Carbon Implantation (Single-X W) Steady
  State followed by 1 Annealing Cycle
• Implantation at T 850C, lt0.5 MeV
• Total C-Fluence 1.6x1022 C/m2 (eq. to 3x105
  shots or ½ day at 10 Hz) ? C/ W 0.5
• Anneal at 2000C 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 850C, flash anneal at
  2000C in 1000 or 100 steps
• Determine Helium release and depth profile.
• Modeling

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Update on Carbon Implantation (ORNL/UNC/UCLA)
ORNL Romanoski/Snead et al. UCLA
Sharafat/Ghoniem et al. UNC Nalin Parikh et
al. Plasma Processes ODell
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The flux of carbon ions into the W armor surface
ensures the formation of tungsten carbide

• 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.
• Carbon ions near the surface are a potential
  source of Carbon to the W/FS interface.

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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.

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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 _at_ 100K eV
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Polycrystalline tungsten implanted with carbon
ions (1.4E19 c/cm2 _at_100KeV) at RTfollowed by
anneal 2000ºC for 5 min.Some surface dilatation
and cracking is apparent.
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Near term goals for carbon implantation work

• Refine carbon implantation experiment at UNC to
  achieve HAPL-relevant dose and conditions.
• Provide sufficient experimental basis to confirm
  UCLA carbon ion implantation model.
• Implant plasma sprayed tungsten materials and age
  at elevated temperature to quantify carbon
  mobility.
• Carry out implant isothermal anneal followed by
  cross section/SIMS analysis for carbon diffusion.
  Carbide formation analyzed using HRTEM.

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Armor/Steel Interface Bond-Strength (UCLA-ORNL)

• Issue Interface-bond strength between the
  W-armor and the substrate needs to be quantified
  in order to provide guidance for further RD of
  the W-armor protected FW.
• GoalsQuantify interfacial bond strength between
  various W-armor and steel combinations
• Approach Use Laser Spallation technique to
  quantify interfacial bond strength
• Experimental Activities
• Determine Dependency of Armor Manufacturing
  Technique (a) Vacuum Plasma Sprayed W-coatings
  3 to 5 samples produced by PSI polished at
  ORNL tested at UCLA post-test characterization
  (X-section TEM) at ORNL(b) IR-Lamp produced
  W-coatings 3 to 5 samples produced and prepared
  at ORNL tested at UCLA post-test
  characterization (X-section TEM) at ORNL
• Determine Effect of Thermal Cycling(a) Vacuum
  Plasma Sprayed W-coatings exposed to IR-Lamp
  cyclic heating 3 to 5 samples produced by
  PSI polished at ORNL tested at UCLA post-test
  characterization (X-section TEM) at
  ORNL(b) IR-Produced W-coatings exposed to
  IR-Lamp cyclic heating 3 to 5 samples
  produced and polished at ORNL thermally cycled
  with IR-Lamp at ORNL samples polished at
  ORNL tested at UCLA post-test characterization
  (X-section TEM) at ORNL
• Sample dimensions 1x1 cm2, 1-mm thick Steel,
  50-70 um thick W-coatings

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Helium Effects and Mirrors
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Helium/Tungsten (UNC, ORNL)

• Provide information on levels of oxygen and water
  impurities in system.
• Following sample handling procedure perform
  low-energy, degraded spectrum accelerated
  irradiation (proposed by Nalin at UCLA meeting)
  on single crystal tungsten at comparable fluence
  to IEC and previous UNC runs.
• Confine threat spectrum implant to the
  100 500 keV region
• Base temperature of 600C to match UCSD work.
• Continue TDS and NDP analysis on single and
  polycrystal tungsten in concert with modeling
  efforts (ORNL, UCLA, UCSD) to determine trapping
  energies.
• Resolve discrepancies in concentration and depth
  results expected vs. NDP results

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Update Helium/Tungsten (UNC, ORNL)
Presented by Nalin Parikh
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Surface damage in W under He-ion irradiation

• Surface morphology observed in the IEC is
  consistent with sputtering.
• SRIM simulations indicate observed surface
  erosion is consistent with sputtering mechanism
  (including alloy dependence).
• Sputtering will accelerate as depressions are
  formed as the incident angle increases, resulting
  in localized sputtering.

Sputtering rate increases with increasing
incident angle and decreasing energy.
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Examining Sputter Rates in W, (ORNL/UNC)

• The influence of sputtering in a He plasma on
  surface condition to be examined using ion
  implantation systems.
• Ion implanters are capable of high currents
  (flux) at lower energy ranges
• UNC accelerator
• W samples to be be implanted with monoenergetic
  He to fluences representative of HAPL targets
  following sample handling procedure.
• 1 x 1019 ions/cm2 at 10 keV (at 0 and 60 to
  beam normal)
• 3 x 1019 ions/cm2 at 10 keV (at 0 to beam
  normal)
• 3 x 1019 ions/cm2 at 110 keV (at 0 and 60 to
  beam normal)
• 7 x 1019 ions/cm2 at 110 keV (at 0 to beam
  normal)
• An additional test will be performed to examine
  the influence of a continuous energy spread on
  sputtering mimicking IEC.
• Following initial positive result the effect of
  sputtering at elevated temperature and function
  of environment (tbd) to be studied.
• Sputtering will be characterized by weight loss
  and surface roughness and measurement tested
  Round Robin fashion with UW.

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Update of He Sputtering in W, (ORNL/UNC)
Experiment is underway (Busby and Leonard,
ORNL with Parikh and crew at UNC.) Currently
helium flux insufficient. Working to increase
flux, otherwise go with carbon beam for which
flux is not an issue. Results within the next
6-8 weeks.
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Effects of Irradiation Damage on Aluminum Mirror
Performance (ORNL/UCSD)

• Issue
• 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 neutron is an important
  issue that has not been well addressed. Changes
  in surface roughness as a result of swelling and
  or sputtering of the near surface layer of the
  mirror, can have a great impact on reflectivity
  and laser induced damage thresholds of the metal
  mirrors. The loss of protective oxide layer
  under neutron irradiation to be determined
• Goal
• The objective of this study is to determine the
  effect that He implantation (phase 1, FY-07) and
  neutron irradiation (phase 2, FY-08) has on the
  reflectivity and surface roughness of an aluminum
  mirror.
• Material
• High purity Al (99.999), 1cm diameter x 2mm
  thick
• High reflectivity at UV wavelengths
• Eliminates added variables associated with
  impurities, multi-phase microstructures or
  interfacial effects between coating and
  substrate.
• Diamond turned mirror surface
• Lowest surface roughness, commercially available
• 30 to 80 Å finish
• Low scattering

• Approach
• Fabrication of high purity Al mirrors by diamond
  turning.
• Phase 1 Exposure of mirror surface to He
  implantation
• Use of medium current ion-implantation to
  determine helium effects and demostrate analysis
  techniques to be used following neutron
  irradiation
• Angles of 0, 30 and 60º from surface normal
• Implantation of 110 keV He ions at 1023 He/m2
  (1019 He/cm2)
• He implantation at 300 ºC
• Phase 2 Exposure to Neutrons (FY-08)
• - HFIR target region. 300C in vacuum.
• - 0.1 and 1 dpa/

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Update Irradiation Damage on Aluminum Mirror
Performance

• Aluminum Mirror Specifications
• Mirrors fabricated by AlumiPlate, Inc. and
  diamond turned by II-VI Infrared.
• High purity (99.9) aluminum electrodeposited on
  polished 6061-T6 grade aluminum substrates
  chosen for simplicity of testing and
  manufacturing.
• Surface finish of mirrors 40 to 45 Å rms.
• Electroplated aluminum coating thickness 200 mm.
• Overall mirror dimensions for testing 1 inch
  diameter x 0.4 inch thickness.
• Same type of mirrors previously evaluated in
  laser threshold damage testing.
• Tasks
• Phase 1, FY-06 He ion implantation
• Collaboration with Nalin Parikh (UNC)
• Round-robin post-implantation testing between UNC
  and ORNL.
• Provide initial evaluation of mirror performance
  under irradiated environment
• and establish PIE techniques for upcoming
  neutron irradiation tests.
• Phase 2, FY-07 Neutron irradiation
• Collaboration with Mark Tillack (UCSD)
• Irradiation at High Flux Isotope Reactor / post
  irradiation evaluation at ORNL.

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Update Irradiation Damage on Aluminum Mirror
Performance

• Experimental Conditions
• Phase 1 He implantation
• Implantation of 110 keV He ions at 1015 , 1016
• and 1017 He/cm2.
• Angles of 0, 30 and 60º from surface normal.
• He implantation at room temperature, assumes
  active cooling in IFE.
• Implantation damage confined to electrodeposited
  coating layer, no substrate effects.
• Ion-implantation to demonstrate analysis
  techniques to be used following neutron
  irradiation.
• Examination
• Reflectivity measurements
• before and after exposure.
• Change in surface roughness.

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Irradiation Damage on Aluminum Mirror Performance

• Phase 2 Neutron irradiation (FY-07)
• HFIR target region, neutron fluence to yield 1019
  to 1021 n/cm2 range.
• Water cooling (65 ºC), may investigate higher
  temperatures.
• Mirror tests under vacuum or low pressure gas
  environment.

HFIR Coolant 60C
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Effects of Irradiation on Multilayer Mirrors
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 radiation 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.
Goal Dielectric mirrors of the type
HfO2/SiO2, HfO2/Al2O3 and Al2O3/SiO2 on sapphire
substrates are of interest for use in the optics
in the laser optics operating at l248 nm for the
IFE program. It is the objective of this study to
evaluate the changes in the dimensional and
surface roughness properties of quarter
wavelength thick monolayer Al2O3, SiO2 and HfO2
films on sapphire substrates. Material E-beam
with ion-assist deposited films of quarter
wavelength thick of Al2O3 (36.5 nm thick), SiO2
(40.5 nm thick) and HfO2 (26.9 nm thick)
deposited on sapphire. Including un-coated
sapphire for control.

• Approach
• Using a mask over each sample produce a step
  function of different He implantation fluencies
  (1018, 1020 and 1022 He/m2) at 110 keV at 0º or
  normal to the surface across the sample.
• Phase 1 (FY-06) He bombardment temperature of
  300 ºC.
• Phase 2 (FY-07) HFIR Neutron Irradiation at
  300C.
• 0.01, 0.1 and 1 dpa.
• Examination
• General visual inspection of films for
  delamination.
• Evaluate step thickness changes across film
  surface correlating to the different He
  fluencies.
• Changes in surface roughness correlating to
  different He implantation fluencies.

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Update Irradiation Damage on Dielectric Mirror
Performance

• Dielectric Mirrors
• Films deposited by E-beam with ion-assist on
  sapphire substrates.
• Quarter wavelength bi-layers of HfO2 / SiO2, HfO2
  / Al2O3 and Al2O3 / SiO2.
• Quarter wavelength monolayers of HfO2 (26.9 nm
  thick), Al2O3 (36.5 nm thick) and SiO2 (40.5 nm
  thick) on sapphire.
• Tasks
• Phase 1, FY-06 He implantation
• Collaboration with Nalin Parikh (UNC)
• Tests conducted on monolayer films only to
  evaluate film/substrate interactions.
• 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.

30
Update Irradiation Damage on Dielectric Mirror
Performance

• Experimental Conditions
• Phase 1 He implantation of monolayer films
• Mask sample to produce a step function of
  different He implantation fluencies
• Fluencies of 1018, 1019, 1020 and 1021 He/m2
  (1dpa max damage at interface)
• Use of 110 keV ions at 0º angle of incidence,
  room temperature.
• Phase 2 Neutron irradiation
• Both mirrors and monolayers
• HFIR target region, 1019 to 1021 n/cm2 (Egt0.1
  MeV.).
• Water cooled (65 ºC) and elevated temperature.
• Non-irradiated controls to evaluate thermal
  cycling.
• Examination
• General visual inspection of films for
  delamination.
• Reflectivity measurements before and after
  exposure of mirrors.
• Evaluate step thickness changes across film
  surface correlating.

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Questions ???