Considerations for Small Chambers

1
Considerations for Small Chambers

• A. René Raffray
• UCSD
• With contributions from M. Sawan (UW), I.
  Sviatoslavsky (UW) and X. Wang (UCSD)
• HAPL Meeting
• University of Rochester's Laboratory for Laser
  Energetics
• Rochester, NY
• November 8-9, 2005

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Considerations on Chamber Development for
Materials Testing with Lower Energy Targets

• Lower yield targets (e.g 30 MJ)
• - Smaller chambers
• - Revisit armor under reduced threat spectra
• If space to be used for materials testing,
  reduced breeding blanket coverage needs to be
  compensated to provide required tritium
• - Optimize blanket for breeding (Be as neutron
  multiplier, 6Li enrichment, structure
  minimization)
• - Flexibility of adjusting breeding for
  different phases of testing
• (e.g. changing 6Li enrichment)
• - No need for power production
• If testing regions are closer to
  micro-explosion and under more intense threat
  spectra, key issue is how to protect them and
  make sure no undesirable impurities enter chamber
  and affect its operation (e.g. target injection
  and survival, laser propagation)

3
Temperature History of W for Example Case with 30
MJ Yield and 5.5 m Chamber
1-mm W on 3.5 mm FS at 500 C Peak
temperature reduced to 1200C Probably lower
than roughening threshold However, He retention
is a concern at lower peak temperature.
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Would Reduced Threat Spectra Allow for
Possibility of Other Armor, e.g. SiC?
SiC Properties - Density 3200
kg/m - Irradiation effects substantially reduce
the conductivity kirrad/kunirrad 0.5 at
1000C
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Chamber with SiC Armor
He retention might be less severe than for W
but would require high operating temperature
(from initial literature survey, but needs
further investigation) Can be bonded to
FS Degradation of properties under irradiation
a concern Erosion due to sputtering and other
processes could lead to T co- deposition in cold
regions
6
Summary

• Investigation of possibility of performing
  material testing with a lower gain target in a
  smaller chamber would include
• - Testing requirements and impact on machine
• - Armor study and development (evaluate W based
  on latest info from our experiments, and look
  at other possibilities, e.g. SiC)
• - Chamber wall
• - Test regions closer to micro-explosion
  (challenging)
• - Blanket development
• - Impact of testing requirements must be
  included (loss of breeding coverage but also
  material choices, e.g. is water required for
  component testing or support? Is it acceptable
  if we choose a Li blanket?)
• - Maximize and provide flexibility of
  adjusting breeding (not enough tritium is a
  concern but too much tritium is also a concern!)
• - No need for power production