A History of Research and a Review of Recent Developments

16
The nature of explosions
of the Ministry of Home Security, was declassified. The predictions of this
theoretical paper were confirmed by measurements of the radius of the luminous
globe from the photographs, as it spread outwards from the centre of the
explosion.
The theory indicated that the radius of the outward propagating spherical
shock wave was linked to the time t since the beginning of the explosion by
the equation
t=0.926R5/2 1/2 –1/2 ρa E ,
(1.11)
when the ratio of specific heats, γ=1.4. As before, ρ a was the atmospheric
density and E the energy released by the explosion. There was doubt about
the validity of the assumption that γ=1.4 at all stages of the explosion, because
at the extremely high temperatures of an atomic explosion γ could be increased
due to dissociation and perhaps affected by intense radiation. However, when
the photographs were examined, Taylor was able to compare the time t in
milliseconds with the radius of the shockwave, and found that the relationship
between and log 10 t was a straight line:
Figure 1.6 Impulses for 1 KT explosions (from Lavoie, ref. 1.16).
(1.12)