Theory of the Fireball
Theory of the Fireball
Theory of the Fireball
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in <strong>the</strong> iso<strong>the</strong>m. sphere. For its occurrence it is important that <strong>the</strong><br />
opacity actually decreases with increasing T at higher temperature. Many<br />
calculations <strong>of</strong> K(T) in this temperature region have been made. Curves<br />
have been compiled, especially by Gilmore,21 and revised as more mor-<br />
mation has become available. The most recent and most extensive calcu-<br />
lation, to my howledge, is by Stuart and matt. 22<br />
AU. calculations agree that T 3 /K(T), which is <strong>the</strong> important quantity<br />
according to ( 5.3), has a pronounced minimum at about T ’ = 2, T = 20,000°.<br />
(The temperature <strong>of</strong> <strong>the</strong> minimum increases slightly with increasing den-<br />
sity. ) Molecules are no longer present at <strong>the</strong>se temperatures, and<br />
absorption is mainly by bound-free electron transitions in atoms and<br />
atomic ions, with some contribution from broadened atomic lines (bound-<br />
bound transitions) whose calculation is <strong>the</strong> most difficult . Radiation<br />
transport, <strong>the</strong>n, is most difficult around Tb = 20,00O0, - and temperatures<br />
around Tb constitute an effective blocking layer for radiation.<br />
Until about 0.5 second, <strong>the</strong> central temperature <strong>of</strong> a 1-megaton sea<br />
level explosion is greater than T according to <strong>the</strong> calculations <strong>of</strong><br />
b’<br />
0<br />
Brode. Radiation flm can <strong>the</strong>n be considered as taking place separately<br />
in an interior and an exterior region. The Stertor flaw is determined<br />
by <strong>the</strong> central temperature Tc, and this flaw generally decreases with ,<br />
time because Tc decreases and with it <strong>the</strong> quantity T 3 /K. The exterior<br />
flaw is dominated by <strong>the</strong> cooling wave and increases with time because<br />
<strong>the</strong> decrease <strong>of</strong> density causes a decrease <strong>of</strong> opacity for any given T.<br />
The two flow regions are separated by a blocking layer in which <strong>the</strong><br />
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