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20 emittance measurements were made for each specimen. The emittance was
determined from the relationship
P
A (Ts - T )
where
P = electrical power input to the test specimen
6 = Stefan-Boltzmann constant
A = area of the test specimen
E = total hemispherical emittance
T s = test specimen temperature, absolute
T = test specimen temperature due to gamma heating, absolute
The emittance stability data obtained for the six samples is also shown in
Table 3. A typical in-pile emittance stability record of an A193 coating sample
is shown in Table 4.
The four A193 tailored coating samples were irradiated to a neutron flux
level of 3 x 1018 nvt. The maximum gamma exposure was 1.9 x 1010R. During
the irradiation test, the samples were maintained at 600*F, 10-5 torr, for 288
hr. The change in total hemispherical emittance of three of the A193 samples
was ~ 1%. The fourth A193 sample experienced a change in emittance of 2%.
This data indicates that the AI93 coating is quite stable in the nuclear
irradiation environment of the SNAP 2 and 10A systems. Vacuum-temperature
stability in these environments has also been demonstrated.
5. Electron Irradiation
The initial high-energy-particles bombardment test of the AI93 tailored
coating was performed in the AI Statitron. Prior to the electron irradiation, the
total hemispherical emittance of the coated specimen was 0.90. During the Stati-
tron test, the coated specimen was maintained at 600*F and received an inte-
grated electron dosage of 3 x 1018, 1.25-MeV energy.
NAA-SR-9908
35
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Crosby, J. R. The Development and Qualification of Thermal Control Coatings for Snap Systems, report, September 30, 1965; Canoga Park, California. (https://digital.library.unt.edu/ark:/67531/metadc1028869/m1/39/: accessed July 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.