Historical research guide · 0358 · 2010
DIRD Advanced Nuclear Propulsion for Manned Deep Space Missions
DIA / AAWSAP contractor
In one minute
This is the Defense Intelligence Agency’s engineering case for a spacecraft that burns pure deuterium. The author — whose preface records a doctorate under Heisenberg and a 1958 invitation to the United States under Operation Paperclip — argues that deuterium is the one nuclear fuel you can refill anywhere, because it comes out of water, and water is on comets, asteroids and most planetary bodies. The difficulty is that deuterium is hard to light. His answer is to shape it as a thin rod and hit one end with a ten-million-ampere, billion-volt proton beam: the beam’s own magnetic field traps the charged fusion products inside the rod, so a detonation wave runs down it and the yield is set by how long the rod is. The craft charges itself to a billion volts by magnetic insulation and reflects each fireball off a magnetic mirror. He then designs the ground test — a mile-long Super Marx generator that makes the same beam on Earth.
Connection
Chapter 12 asks what it actually takes to make a small, clean, non-fission fusion burn go, and this is the most complete engineering answer in the DIRD series. Its central trick — using a beam’s own magnetic field to hold the reaction products inside the fuel so the burn propagates — is the same idea chapter 9 meets again in plasmoids and charge clusters, and the Super Marx generator gives the whole programme a named, buildable next measurement on the ground.
From the source
Deuterium is the rocket fuel of choice because it can be refilled anywhere: it is extracted from water in three steps, and water is abundant on comets, asteroids and most planetary bodies, whereas helium-3 would have to be mined from the Moon or Jupiter’s atmosphere. And the deuterium-deuterium detonation is cleaner than it looks — the instantaneous burn of its own tritium and helium-3 products yields 26.8 MeV in charged fusion products against 16.55 MeV in neutrons from six deuterons, so 62 percent of the energy comes back as charged particles a magnetic mirror can reflect, against 20 percent for deuterium-tritium.Deuterium, Argon Ion Lasers, and KeV Superexplosives, pp. 1-3; Deuterium as the Preferred Nuclear Rocket Fuel, p. 5; Table 1
Magnetic insulation makes a gigavolt spacecraft possible: if a magnetic field parallel to a charged surface exceeds the electric field in the same electrostatic units, field-emitted electrons drift along the surface instead of breaking down to the anode. An ordinary 2 by 10⁴ gauss field therefore supports 6 by 10⁶ V/cm, and a conductor 10 metres across holds about 6 gigavolts. The craft, built as a hollow cylinder that is also its own field coil, charges itself inductively against a surrounding electron cloud whose density stays well below the Brillouin limit.Magnetic Insulation and Inductive Charging, pp. 3-5; Delivery of a GeV Proton Beam Onto the Deuterium Fusion Explosive, pp. 15-16
The ignition scheme is the report’s central claim: focus a 10⁷-ampere GeV proton beam on one end of a slender cylindrical deuterium rod, and the beam’s own azimuthal magnetic field entraps the charged fusion products inside the rod — every critical current in Table 2 lies below 3.84 by 10⁶ amperes, so a 10⁷-ampere beam traps them all. The sphere condition of a density-radius product of 10 g/cm², which would need about 10⁴ megajoules and is out of reach for non-fission ignition, is thereby replaced by a cylinder condition, and the fusion gain depends only on the length of the rod.Magnetic Entrapment of the Charged Fusion Products, pp. 6-9; Table 2; Figure 1
Single GeV protons would pass straight through dense deuterium, but an intense beam does not: the electrostatic proton-deuteron two-stream instability, sharpened by a collisionless magnetohydrodynamic shock whose thickness is about 10⁻² cm, gives a stopping length of about 1.2 by 10⁻² cm in hundredfold-compressed deuterium. A gigajoule delivered in 10⁻⁷ seconds — a beam power near 30 petawatts — is therefore dissipated into a sub-centimetre volume at the end of the rod, which is the ignition energy the scheme needs.Magnetic Entrapment of the Charged Fusion Products, pp. 9-10
An autocatalytic detonation wave would solve the neutron and radiator problem from inside: soft X-ray bremsstrahlung from the burn zone runs ahead of the front and precompresses the unburned deuterium, and at a number density of about 10²⁶ per cm³ the neutrons are absorbed within the burning plasma column itself. That removes most of the heat load on the craft and raises the specific impulse by the factor 1.275, taking the maximum exhaust velocity from 1.5 to 1.9 by 10⁹ cm/s — 6.3 percent of the speed of light.Neutron Entrapment in an Autocatalytic Thermonuclear Detonation Wave, pp. 18-20; Figure 6
The concept can be tested on the ground without launching anything: a Super Marx generator — about 100 magnetically insulated coaxial capacitors, each 15 metres long, charged to 10 MV by pairs of conventional Marx banks and then switched in series to 1 gigavolt, storing a gigajoule along a 1.5 km evacuated tunnel — produces on Earth the same 10⁷-ampere GeV proton beam the charged spacecraft would produce in space. The report’s judgement is that since pure deuterium ignition would be a breakthrough in fusion, the expenditure would be well justified.Testing the Deuterium Microdetonation Concept, pp. 20-25; Figures 8-13
The way in
https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_11-DIRD_Advanced_Nuclear_Propulsion_for_Manned_Deep_Space_Missions.pdfHow to cite it
DIA / AAWSAP contractor (2010) DIRD Advanced Nuclear Propulsion for Manned Deep Space Missions https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_11-DIRD_Advanced_Nuclear_Propulsion_for_Manned_Deep_Space_Missions.pdf