Defense Intelligence Reference Document Advanced Nuclear Propulsion For Manned Deep Space Missions

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Because the 6 charged fusion products are accompanied by 9 electrons, they have to
share their kinetic energy with 9 electrons. This reduces the maximum specific impulse
by the factor .j(6+9)/6 = ✓25 to~ = 0.95x 109cm/s.
A reduction of the specific impulse does not occur if the electrons have enough time to
escape the burning plasma behind the detonation front; that is, in a time shorter than
the time for them to be heated by the charged fusion products.
The time needed for the electrons to be heated by the charged fusion reaction products
can be computed from the range Ao of the charged fusion products and their velocity v
in a plasma at the temperature T. For the He4 fusion products, the range is given by
Ao= a(kT) •
112
, a= 2.Sx 10 34 [cgs] (8)
n
This time is
A0 a(kT) ' 12
T = = (9)
\! 11 l'
It then has to be compared with the time the electron can escape the burning plasma
behind the detonation front, given by
(10)
where ro is the radius of the burning deuterium cylinder, and ve the electron velocity.
One thus has
( 11)
Putting n = 10 23 cm· 3 , T:::::: 108 K with '\ ~ 109 cm/s, v ~ 109 cm/s, one finds t,,s,./r~
2.51;1 • Therefore, t,." < rrequires that 'ii< 0.4 cm.
To reach the highest specific impulse possible, one should make the deuterium cylinder
as thin as possible.
Magnetic Entrapment of the Charged Fusion Products and
the Stopping of the Proton Beam in Dense Deuterium
If a fission bomb is used to trigger a thermonuclear detonation, so much energy is
available that almost any radiation implosion configuration is likely going to work. As an
example, one may place a fission bomb and a sphere of solid deuterium in a shell of
6
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