Theory of the Fireball

where e- is the number of electrons per air atom, the quantity tabulated
in Gilmore,l3 and hv is the quantum energy in ev. Table I11 gives some
numbers for hv = 1 ev, four temperatures and three densities. At 8000°7
the free-free absorption is substantial, at lawer temperatures negligible .
At 12,000° the transitions are mostly in the field of -7 ions i.e.,
Meyerott's numbers need only slight correction, and the absorption is
large
Table 111.
T
47 OOo
6,000
87 000
12,000
Free-Free Absorption Coefficients (cm -1
)
for hv = 1 ev
5.5-& 1.05'5 1.9-7
Note: for each value, the power of 10 is indicated by a superscript.
Another cause of absorption in the infrared is the vibrational bands
of NO, which have an oscillator strength of and hv = l/k ev.
The resulting absorption coefficient is about
where (NO) is the
percent at p/po =
-1
cm e While this
number of NO molecules per air atom. Tnis is a few
1 and T = 4000 to 8000°, giving p = 2 X lom3 to
is of the order of magnitude relevant for emission,
33