ESATSE Tritium Monitoring

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Modeling and Demonstration of Centering Forces
in Capsule FormationJ. T. Bousquet, G. W. Flint,
B. W. McQuillan, R. W. Petzoldt, D.T. Goodin, J.
F. HundGeneral Atomics, Inertial Fusion
Technology, San Diego, California
IFT\P2006-038
Mathematical modeling of forces in the Z
direction (along gravity) for a sphere within a
sphere.
IFE target specifications require the
non-concentricity of a shell be below 1.
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• Our definition of non-concentricity

• The force of gravity down of the W1 ball
  within the O1 ball

• The journal bearing force for a sphere in a
  sphere

Poor NC
Better NC, lt 5
Additional orthogonal view provides ? z

• Stokes-Einstein equation for drag on a sphere

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Currently, roto-beakers are used to improve
non-concentricity.
Model is following data for similar systems in a
single shell testing (SST) device.
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? (rps)

• The shell is placed in a cuvette surrounded by a
  liquid.
• The cuvette is mounted on a small table top
  lathe
• Attached to the lathe is a programmable stepper
  motor.

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3
5
6.66
-6.66
Roto-Beaker
6 inches
Tangential shear may affect the centering of a
shell.
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Curing of polymer shells in the SST has shown
great improvement.
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By utilizing the theoretical model, results from
the SST have improved, and should continue to
improve with better density matching and an
improved rotational profile.

• As tangential shear is applied to the outer
  surface, fluid flows in between the inner and
  outer spheres, forcing the inner sphere towards
  the center
• When full body rotation is achieved the
  centering force approaches zero, therefore
  tangential shears acceleration is varied
• Centering force must overcome gravity-may
  require closer density matching