Fusion driver study. Final technical report, April 1, 1978-March 31, 1980 Page: 66 of 339
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Once lasing has occurred, the 02°0 level of the \>2
(bending) mode will be populated, either by intermode crossing
between the two Fermi degenerate levels if 10.6m radiation is
used, directly if 9.6 m radiation is used or in combination if
both bands are employed. The time constant for the
10°0 02°0 equilibrization is not well known but at least
one measurement(estimates the rate at ~ 5 ns (at 1 atm) so
that there is not significant equilibrization between these two
levels on a short-pulse time. On .a vibrational repump time,
however, these two levels are in equilibrium.
In gas mixtures where the CO2 concentration is at least
greater than half, the thermalization of the entire i»2 mode
occurs rapidly, and is assumed to be complete on a rvv time
scale. It follows that the rate of transferring vibrational
energy to translational energy, i.e., heat, is governed by
rd2' The l°wer level rate coefficient is plotted in Figure
24 and for CO2 or N2 is quite low, of the order of
2-4 x 10“15 cm^ part"! s~l or a deactivation time con-
stant of ~ 20 ms. Hence, in N2/CO2 mixtures, there is no
significant depopulation of the ^ vibrational manifold on a
short-pulse time scale or a vibrational transfer time scale or
even on a discharge pumping time scale. It is possible to in-
crease the V2 deactivation rate as much as one to two orders
of magnitude by adding quantities of H2 or ,He as indicated in
Figure 24 but as shown below, this requires impractically large
quantities of either gas.
The quantity of H2 or He which would be'required for an
effective lower state deactivator is estimated by requiring
that the lower state deactivation rate -be comparable to the
vibrational transfer rate, i.e.,
Since the total mole fractions of all the constituent species
must equal unity,
rd2 “ Tvv
or
4> He,N2 = (rd2 nT Kd2)_1
= (T vv ^T ^ds) "*■
k(n2, co2)
^ He ,N2 + ^N2 + '/'CO2 “ 1
^7AVCO EVERETT
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Friedman, H.W. Fusion driver study. Final technical report, April 1, 1978-March 31, 1980, report, April 1, 1980; United States. (https://digital.library.unt.edu/ark:/67531/metadc1071615/m1/66/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.