ly
is atomic rather than molecular, and calcclaticns vhick asscoe sabiest pressure and temperature at 250,000 feet hawe been repeated.
Again the overall
performance curwe is presested in Fig. 5.3, which is based oo 100-percent
efficiency, prowided all debris swept cut by an area of the impactor were
collected.
Under all circumstances the collection is substantially the some
for particles having diameters larger then 15 x 10? microm, Below this
walue there is some variation becamse of speed and air conditions.
at low
densities, the impaction and diffosion owerlap in effectiveness to allow
collection of all debris passing through the impactor.
Om the orber hand,
less air flows through the impactors under these conditions.
At higher a-
bient densities, the flow through the impacror is large, but izpaction and
diffusion are less effective.
On tt= whole, the inpactor performance is
markedly insensitive to conditions under which it samples.
The above considerations vere based on a sampler rocket passing upward
through the debris.
Should the LASL debris-rise calculation be correct, the
sampler rocket would never overtake the debris cloud, since the upward speed
of this cloud exceeds that of the rocket by a factor of 2.5.
Since the LASL calculation seemed reasonable, a sampler rochet equipped
with deflectors on the side ports was positioned to be at apogee above the
burst at zero time.
with accuracy.
Performance of this arrangewent could oot be predicted
It was believed probable that debris would be solecular be-
cause of the rapid expansion accompanying the rise.
In this case collectioa
would be accomplished by diffusion. About half the debris of the diverted
flow would be collected on the impactor plates.
‘The remminder would diffuse
to internal chanel walls before reaching the impactor plates.
Sampler Effectiveness.
In determining expected impactor performance
under various conditions, maximm sample size mist be considered.
Debris
is assumed to be unifornly distributed in a sphere which bas a radius of
15,000 feet.
It is further assumed that the debris is of sufficient particle
size to insure 100-percent collection.
If the sampler rocket travels ou a
sphere diameter, a volume of 2r4 would be svept out by the impactor, where r
is cloud radius and A is impactor area
137