HAPL Modeling ? Ion and Heat Transport

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HAPL Modeling ? Ion and Heat Transport

• Qiyang Hu, Nasr Ghoniem, Shahram Sharafat, Mike
  Anderson
• Mechanical Aerospace Engineering
• University of California, Los Angeles
• May 15th, 2006

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Outline

• HEROs Helium Diffusion
• Model revisited
• Results updated
• Future schedule
• Analytical approach temperature profile
• Greens function formulation
• Results comparison
• Plans for next step

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• HEROs Helium Diffusion
• Analytical approach temperature profile

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Previous HEROs code has serious numerical
instability problem

• In most cases
• Time to be simulated lt 100 ?sec
• Running Time gt 6 hours
• Time step gt 2000 steps
• Temperature range lt 2000 K

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HEROs model is completely revisited

• Still, spatial kinetic
• Simplify the equation
• Ignore some cluster effects
• (e.g. vacancy clusters, interstitial clusters
  etc.)
• 18 variables/equations ? 13
• Ignore bubble coalescence
• Start from spatial-independent case

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HEROs numerical scheme
Temperature profile
Within a bin, each C(i) isin an average sense
Implantation profile

W back
variable bin size
W front
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We want to use our new HEROs code to model
different conditions.
We re-simulated UWMs steady implantation case
constant temperature
constant temperature
Helium Implantation
Damage
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Experiments (Cipiti Kulcinski, 2004) show
1160 C 2.6x1016 He/cm2-s 2.5 min.
990 C 8.8x1015 He/cm2-s 7.5 min.
730 C 2.2x1015 He/cm2-s 30 min.
40 KeV He On W 5?1018 ion/cm2
Temperature Pore Size Pore Density
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New HEROs code is stable and gives the correct
information about pore sizes
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So does the pore density
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HEROs also gives the spatial distribution
information (average sense)
40 KeV Temperature1160 oC Bin Number20
Total width10?m
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Helium retention
Most of He are in grain boundary
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Capabilities of new HEROs code are largely
improved
HEROs Total time to be simulated Running time Required time steps Temperature range
Previous lt100 ?sec gt6 hrs gt2000 steps lt2000 K
Current gt106 sec lt5 mins lt 100 steps lt3500 K
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Planning on HEROs

• Implement pulsed cases
• UWM
• UNC
• IFE
• Add bubble coalescence
• Exceed the 0-order (average) description
• Include 1st-order size distribution

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• HEROs Helium Diffusion
• Analytical approach temperature profile

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We are doing 1-D heat diffusion

• Well-known equation
• Adiabatic boundary condition
• If material properties are constant

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Numerical approximations

• Discrete time steps
• Volumetric heating ? Surface heat

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Good agreement is achieved
(Blanchard 2005)
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Planning

• Real cases of heating
• Volumetric heating
• IFE condition
• Couple temperature into HEROs
• Same kinetic-equation structure
• 13 variables/equation ? 14

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Thanks!