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

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cylinder, compressing it to high densities, while the bulk of the proton beam energy
heats and ignites the deuterium cylinder at its end, launching in it a detonation wave.
If the GeV -10 7-ampere proton beam passes through background hydrogen plasma with
a particle number density n, it induces in the plasma a return current carried by its
electrons, where the electrons move in the same direction as the protons. But because
the current of the proton beam and the return current of the plasma electrons are in
opposite directions, they repel each other. Since the stagnation pressure of the GeV -
107-ampere proton beam is much larger than that of the electron return current, the
return current electrons will be repelled from the proton beam toward the surface of the
proton beam.
The stagnation pressure of a GeV proton beam is (MH proton mass)
(19)
For n1,-='= 2x J010 cm- 3 , one obtains p1 :::: 3x 101.1 dyn/cm 3 . For the electron return current,
one has (m electron mass)
(20)
With the return current condition nJ:i\, = np'1 , where for GeV protons i\ :::: c, one has
v,./c=n,/n,, (21)
Taking the value n" =5xl0 22 cm- 3 , valid for uncompressed solid deuterium, one obtains
v,. :::: 104 cm/sand hence Pe :::: 5 x 103 dyn/cm 2 . This is negligible against p1, even if ne is
103 times larger, as in highly compressed deuterium. The assumption that the magnetic
field of the proton beam is sufficiently strong to entrap the charged fusion products
within the deuterium cylinder is therefore well justified.
Solution in Between Two Extremes
With chemical propulsion, manned space flight to the Moon is barely possible and only
with massive multistage rockets. For manned space flight beyond the Moon, nuclear
propulsion is indispensible. Nuclear thermal propulsion is really not much better than
advanced chemical propulsion. Ion propulsion, using a nuclear reactor to drive an
electric generator, has a much higher specific impulse but not enough thrust for short
interplanetary transit times needed for manned missions. This leaves propulsion by a
chain of fission bombs (or fission-triggered fusion bombs) as the only credible option.
There the thrust and specific impulse are comparatively huge, but a comparatively
small explosive yield is desirable. Making the yield too small, the bombs become
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