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Theory of the Fireball

Theory of the Fireball

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esult <strong>of</strong> <strong>the</strong> three-dimensional considerations, <strong>the</strong> one-dimensional for-<br />

.<br />

mda (5 -35 yields a decrease <strong>of</strong> p/p as t -'.<br />

Using (5.33), a constant mass absorption coefficient requires<br />

-1/3n 4/20<br />

T; - P "P (6.28)<br />

Thus in three dimensions, <strong>the</strong> temperature continues to increase slowly<br />

after <strong>the</strong> cooling wave reaches <strong>the</strong> iso<strong>the</strong>rmal sphere. If we assume tinat<br />

times up to x = 2.5 in Table IX are significant, tne pressure decreases<br />

by about a factor <strong>of</strong> 3 in Stage C 11, and <strong>the</strong> temperature <strong>of</strong> <strong>the</strong> radiating<br />

d<br />

layer increases by about 513 according to (6.28). The radiated power,<br />

2 14<br />

being proportional to R1 T1 , may increase by about 10:'. up to x = 2,<br />

and <strong>the</strong>n decreases due to <strong>the</strong> shrinkage <strong>of</strong> <strong>the</strong> radiating surface.<br />

One prediction <strong>of</strong> this <strong>the</strong>ory is that <strong>the</strong> temperature,as well as<br />

<strong>the</strong> radiated power. has a ra<strong>the</strong>r flat second maximum while <strong>the</strong> iso<strong>the</strong>rmal<br />

sphere radiates<br />

treatment <strong>of</strong> J1<br />

I -<br />

away its energy. The slaw vwiation <strong>of</strong> T justifies <strong>the</strong><br />

1<br />

as constant in Sec. 6b .<br />

7. TRANSPARENT FIREBALL ( Stage D)<br />

After <strong>the</strong> iso<strong>the</strong>rmal sphere has been eliminated by <strong>the</strong> cooling wave,<br />

<strong>the</strong> fireball is transparent if we neglect <strong>the</strong> effect <strong>of</strong> toe bomb debris.<br />

At this time <strong>the</strong> pressure is given by (6.21), <strong>the</strong> average temperature <strong>of</strong><br />

<strong>the</strong> 'barn" region is about 70Oo0, and <strong>the</strong> corresponding density is about<br />

80

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