# H bombs

John K Clark (johnkc@well.com)
Tue, 3 Mar 1998 10:56:27 -0800 (PST)

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On Tue, 3 Mar 1998 Eugene Leitl <eugene@liposome.genebee.msu.su> Wrote:

>What is the energy flux upon a square meter of surface 300 m away
>from a 10 m-radius sphere radiating as a 100 MK blackbody?

Let's see, we can find the energy density at the surface of the hot sphere at
temperature T with the formula
(8PI^5)*(kT)^4/(15h^3 * c ^3) = (2.27*10^-7 watts/M^2*K^4)*T^4 .

If T is 10^8 degrees Kelvin then the sphere would radiate 2.27 *10^25
watts per square meter, that's over 22 million billion billion watts per
square meter!

A sphere of 300 meters has a radius 30 times greater than one of 10 meters,
30^2 = 900 so at 300 meters the energy density would be 900 times weaker, or
2.52 * 10^22 watts per square meter, just a little over 25 thousand billion
billion watts per square meter.

>Are you really proposing that the peak forces generated are
>sufficient to deformate a macroscopic object made of, say, 1 cm
>sheet steel?

Yes. Near the Earth the radiation from the sun is only about a thousand watts
per square meter, that's why solar sails have to be so big, in this case our
target 300 meters from the H bomb would experience radiation pressure
25 billion billion times greater, and that would be a hell of a jolt.

Remember I'm only talking about the radiation pressure of the light, the
rocket effect would substantial add to the pressure the target received but
it's not as easy to calculate.

>I thought the Russies peaked that on Novaya Zhemlya (20 MT expected,
>60 MT estimated real yield). This has been no ground blast, though.

True.

>>Me:
>>Maybe, but then the design would be inefficient because if the foam
>>was that ephemeral then most of the X rays energy would pass
>>through all the foam and be wasted, it would not be available to
>>compress the fusion cylinder. Why not use radiation pressure?

>Maybe all they wanted was to compress the material to the critical
>density to be ignited by the fission primer.

Doesn't seem likely, if that was all that was needed then you wouldn't need
a primary trigger, it could be done with chemical explosives.

John K Clark johnkc@well.com

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