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

UNCLASSIFIED//FIHl 8FFHil.t.k Wfili IH.k\f
If the charged fusion products are entrapped within the deuterium cylinder, and if the
condition pz. > 10g/cm 2 is satisfied, and finally, if the beam energy is large enough that
a length z > (10/p) cm of the cylinder is heated to a temperature of 109 K, a
thermonuclear detonation wave can propagate down the cylinder. This then leads to
large fusion gains.
The stopping length of single GeV protons in dense deuterium is much too large to fulfill
inequality (Reference 16). But this is different for an intense beam of protons, where
the stopping length is determined by the electrostatic proton-deuteron two-stream
instability (Reference 14). In the presence of a strong azimuthal magnetic field, the
beam dissipation is enhanced by the formation of a collisionless shock (Reference 15)
with the thickness of the shock by order of magnitude equal to the Larmer radius of the
deuterium ions at a temperature of 109 K, which for a magnetic field on the order of 107
G is on the order of 10-2 cm. For the two-stream instability alone, the stopping length is
given by
( 17)
where c is the velocity of light, w; the proton ion plasma frequency, and E: = n1,/n, with
n the deuterium target number density and nb = 2xl0 16 cm· 3 , the proton number
density in the beam. For a hundredfold compressed deuterium rod, one has
n=5xl0 24 cm· 3,with w,=2xl0 15 s· 1 . One finds that c=4xl0-C/ and /4~1.2xl0- 2 cm. This
short length, together with the formation of the collision less magneto-hydrodynamic
shock, ensures the dissipation of the beam energy into a small volume at the end of the
deuterium rod. For a deuterium number density n = S x 10 2--1cm- 3 , one hasp= 17 g/cm3,
and to have pz > 10 g/cm 2 requires that z 2: 0.6 cm. With /4 < z, the condition for the
ignition of a thermonuclear detonation wave is satisfied. The ignition energy is given by
( 18)
where T ~ 109 K.
For hundredfold compressed deuterium, one hasm· 2 = ur-'cm 2 , where initially it
wasw 2
= 10- 1
cm 2
• Withm- 2
= 10-.1 cm 2
and z = 0.6cm, one finds that E,g,, s; 10 1
~ erg or :5
lGJ. This energy is provided by the 107-ampere GeV proton beam lasting 10· 7 seconds.
The time is short enough to ensure the cold compression of deuterium to high densities.
For a 10 3-fold compression, found feasible in laser fusion experiments, the ignition
energy is 10 times less.
In hitting the target, a fraction of the proton beam energy is dissipated into X-rays by
entering and bombarding the high Z material cone, focusing the proton beam onto the
deuterium cylinder. The X-rays released fill the hohlraum surrounding the deuterium
9
UNCLASSIFIED/1FFIUl 8FFIIIAk l!Hiili IH.k\f