Armor Configuration

1
Armor Configuration Thermal Analysis

• Parametric analysis in support of system studies
• Preliminary scoping analysis of the use of a
  porous armor layer
• A. René Raffray
• UCSD
• HAPL Program Meeting
• University of Wisconsin, Madison
• September 24-25, 2003

2
Integrated Chamber Armor/FW/Blanket Analysis
Required for Chamber System Studies

• Chamber engineering constraints are set by
  limits on maximum temp. and cyclic temperature
  behavior of armor (W) and of structural material
  (ferritic steel), which depend on
• IFE system parameters
• e.g. yield, rep rate, chamber size, protective
  gas density
• Chamber first wall and blanket design
  parameters for example configuration
• - e.g. coolant inlet and outlet temperatures,
  first wall structural material thickness,
  armor thickness and properties (including
  engineered materials) and heat transfer
  coefficient at coolant

3
Example Results Comparing W Temperature Histories
for Armor Thicknesses of 0.05 mm and 0.5 mm,
respectively
dW0.05mm
dW0.5mm
154 MJ yield No gas Rep Rate 10 Rchamber 6.5
m dFS 2.5mm Tcoolant 500C
Not much difference in maximum W temperature
and in number of cycles to ramp up to the maximum
temperature level
4
Example Results Comparing FS Temperature
Histories for W Armor Thicknesses of 0.05 mm and
0.5 mm, respectively
dW0.05mm
dW0.5mm
Substantial differences in max. TFS and cyclic
DTFS at FS/W interface depending on dW Can
adjust Tmax by varying Tcoolant and
hcoolant Design for separate function and
operating regime - armor function under cyclic
temperature conditions - structural material,
coolant and blanket operation designed for
quasi steady-state
154 MJ yield No gas Rep Rate 10 Rchamber 6.5
m dFS 2.5mm Tcoolant 500C
5
Maximum TW, TFS, DTFS as a Function of Armor
Thickness for Example Parameters
Maximum W temperature is virtually
constant over range of armor thicknesses,
3050C
Must be integrated with chamber system modeling
for consistent overall blanket and armor design
parameters For given IFE conditions and chamber
parameters, set maximum possible dW (to minimize
cyclic DTFS and FS Tmax and provide lifetime
margin) that would accommodate - maximum
allowable TW - fabrication
6
Procedure for Parametric Armor Analysis

• Utilize consistent parameters from steady state
  parametric study of example blanket/FW/power
  cycle configuration (FS/Li/Brayton Cycle)
• - parameters evolved on the basis of maximizing
  cycle efficiency while accommodating max.
  allowable TFS (800C for ODS FS) and TFS/Li
  (600C)
• - Tcoolant, convective heat transfer
  coefficient, and FS thickness set

1-mm W thickness assumed for analysis
- maintain DTFS lt20 C for example cases
- also applicable for higher energy density
cases as increasing the W thickness in the
range of 1 mm has only a 10C effect on the
max. TW - could be regarded as a mid-life or end
of life scenario also
For given fusion power from blanket analysis,
calculate combination of yield, chamber radius
and protective gas density which would maintain
max. TW lt assumed limit (2400 C) - Utilize D.
Haynes/J. Blanchards approximation to account
for gas attenuation - Reduction in photon/burn
ion/debris ion of 9/1/29 for 10mtorr Xe and
R6.5 m - Reduction of 16/2/48 for 20mtorr Xe
and R6.5 m - Conservative assumption shift ion
energy spectrum correspondingly - Heat in gas
reradiated to surface over time 300-700 ms
7
Summary of Armor Parametric Results for a Fusion
Power of 1800 MW
These results are used as input in the system
code in combination with results from the
blanket/FW/cycle parametric analysis for the
given fusion power
8
Summary of Armor Parametric Results for a Fusion
Power of 3000 MW
9
Scoping Study of Thermal Performance of Armor
with a Porous Layer

• - PPI plans to develop nano-scaled engineered W
  for armor applications as part of current SBIR
  Phase I grant
• Work with PPI to help optimize material
  microstructure characteristics (e.g.
  microstructure characteristic dimension,
  porosity, pore sizes, heterogeneity)
• Minimize resistance to migration and release of
  implanted He
• Provide adequate heat transfer performance
• Use RACLETTE-IFE with adjusted material property
  data and energy deposition input to help
  understand impact on integrated chamber
  armor/FW/blanket system

10
Ion Energy Deposition as a Function of
Penetration Depth for a W Armor with a 10mm
Porous Layer
Maximum energy deposition decreases and energy
penetration depth increases with increasing
porosity of the porous layer
11
Ion Energy Deposition as a Function of
Penetration Depth for a W Armor with a 10mm
Porous Layer
For these scoping calculations, fully
dense k and r of W scaled to density of porous
region Maximum armor temp. increases
appreciably with increasing porosity but not
with porous region thickness past ion
penetration depth (lt10mm) Important to
minimize porosity of porous region but
there is flexibility in setting its
thickness Porous region might reduce peak
thermal stresses on armor and allow for higher
max. temp. limits
12
Assessing Relative Effects of Decrease in Thermal
Conductivity and Density and Change in Ion and
Photon Energy Deposition Profile in Porous Region
Effect on max. TW of decrease in k in
porous region dominates opposite effect due to
broadening of energy deposition Similar
results for different thicknesses of
porous region (10 and 100 mm)
13
Conclusions
Parametric study of armor performed to provide
input for initial system studies - W
thickness affects DTFS at FS/W interface but
virtually not max. TW - Design armor based on
transient conditions and FW and blanket based on
quasi steady-state conditions - Study has
yielded combination of yield, chamber radius and
protective gas density which would maintain
max. TW lt assumed limit (2400 C) for different
fusion powers and consistent blanket/FW/cycle
parameters

• Scoping study of thermal performance of porous
  armor region has been performed
• - Max. TW dependent on porosity of porous
  region but virtually not on its thickness
  (past energy deposition depth)
• - Effect of lower thermal conductivity of
  porous region outweighs counterbalancing
  effect of energy deposition spread in porous
  region
• - Optimization of porous material based on
  providing least resistance to migration of
  implanted He ions while accommodating maximum W
  temperature constraint (i.e. providing
  acceptable heat transfer performance)