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

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• Bombardment of a solid target with beams or by hypervelocity impact, followed by a
convergent shock wave.
BOMBARDMENT OF A SOLID TARGET WITH AN INTENSE
RELATIVISTIC ELECTRON OR ION BEAM
This possibility was considered by Kidder (Reference 20), who computes a pressure of
SO Mb, if an iron plate is bombarded with a 1-MJ - 10-MeV - 106 A relativistic electron
beam, focused down to an area of 0.1 cm 2 . Accordingly, a 2-MJ beam would produce
100 Mb. Instead of an intense relativistic electron beam, one may use an intense ion
beam. It can be produced by the same high-voltage technique, replacing the electron
beam diode by a magnetically insulated diode (Reference 21).
Using intense ion beams has the additional benefit that the stopping of the ions in a
target is determined by a Bragg curve, generating the maximum pressure inside the
target, not on its surface.
HYPERVELOCITY IMPACT
A projectile with the density p :::::: 20 g/cm 3 accelerated to a velocity v = 30 km/s would,
upon impact, produce a pressure of p z 100 Mb. The acceleration of the projectile to
these velocities can be done by a magnetic traveling wave accelerator.
BOMBARDMENT OF A SOLID TARGET WITH BEAMS OR BY
HYPERVELOCITY IMPACT, FOLLOWED BY A CONVERGENT SHOCK
WAVE
If, upon impact of either a particle beam or a projectile, the pressure is less than 100
Mb (for example, only on the order of 10 Mb) but is acting over a larger area, a tenfold
increase in the pressure over a smaller area is possible by launching a convergent
shock wave from the larger area on the surface of the target onto a smaller area inside.
According to Guderley, the rise in pressure in a convergent spherical shock wave goes
as r - 0 -9 , which means 100 Mb could be reached by a tenfold reduction in the radius of
the convergent shock wave.
While it is difficult to reach 30 km/s with a traveling magnetic wave accelerator, it is
easy to reach a velocity of 10 km/s with a two-stage light gas gun.
We assume an equation of state of the form p/ p 0 = (n/n 11 Y. For a pressure of 100 Mb =
1014 dyn/cm 2 , we may set y= 3 and p 11 = 10 11 dyn/cm2, p 11 being the Fermi pressure of
a solid at the atomic number density 110 , with n being the atomic number density at the
elevated pressure p > Pn. With d = n- 113, where dis the lattice constant, one has
I I _, ''ddo=(PPn) ( 41)
Such a lowering of the inneratomic distance is sufficient for the formation of molecular
states.
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