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

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Assuming the spacecraft reaches a velocity of t' = 100 km/s = 107 cm/s, the velocity
needed for fast interplanetary travel, one has t..M = l0H g, requiring N = M1 ; 1111) = I04 1-
kiloton fusion bombs, releasing the energy £ 1
, = 5 x 10 19 x 104 = 5 x 1023 erg. By
comparison, the kinetic energy of the spacecraft E, = (I/2)M0 v 2 = Sx 1022 erg is 10
times less. In reality it is still smaller, because a large fraction of the energy released
by the bomb explosions is dissipated into space.
One can summarize these estimates by concluding that a very large number of nuclear
explosions are needed, which for fission explosions, as well as for deuterium-tritium
explosions, would become very expensive. This strongly favors deuterium, which is
more difficult to ignite than a mixture of deuterium with tritium but is abundantly
available. The following text tries to show how bomb propulsion solely with deuterium
might be possible.
The Nonfission Ignition of Small Deuterium Nuclear
Explosives
With no deuterium-tritium (DT) microexplosions yet ignited, the nonfission ignition of
pure deuterium (DD) fusion explosions seems to be a tall order. An indirect way to
reach this goal is by staging a smaller DT explosion with a larger DD explosion. There
the driver energy, but not the driver, may be rather small. A direct way requires a
driver with order of magnitude larger energies.
The generation of GeV potential wells, made possible with magnetic insulation of
conductors levitated in ultrahigh vacuum (in a laboratory on Earth), has the potential to
lead to order of magnitude larger driver energies (Reference 1). It is the ultrahigh
vacuum of space that enables this to be achieved without levitation. Therefore, the
spacecraft, acting as a capacitor, can be charged up to GeV potentials.
If the spacecraft is charged to a positive GeV potential, a gigajoule intense relativistic
ion beam below the Alfven current limit can be released from the spacecraft and
directed to the deuterium explosive for its ignition. If the current needed for ignition is
below the Alfven limit for ions, the beam is "stiff." The critical Alfven current for protons
is / A = 3.1 x 107 JJr [A], where /J = vi c, r = (1 - /3 2 )
112
, with t' the proton velocity and c the
velocity of light. For GeV protons, IA is well in excess of the critical current (Reference
15) to entrap the DD fusion reaction products, the condition for detonation (Reference
13).
In a possible bomb configuration shown in Figure 2, the liquid (or solid) D explosive has
the shape of a long cylinder, placed inside a cylindrical "hohlraum" h. A GeV proton
beam I coming from the left, in entering the hohlraum, dissipates part of its energy into
a burst of X-rays compressing and igniting the D bomb-cylinder. With its gigajoule
energy lasting less than 10-7 seconds, the beam power is greater than 10 10 watts,
sufficiently large to ignite the D explosive. The main portion of the beam energy is
focused by the cone onto the deuterium rod, igniting at its end a detonation wave.
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