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December 03, 2008

Micro-Fusion For Space Propulsion and Weapons with Gigavolt Super Marx Generator, Proton Beams or Argon Ion Lasers

Micro-fusion work of Friedwardt Winterberg from the 1950's-1970s was recently declassified. Winterberg had several ideas for using micro-fusion without fission bomb triggers to generate nuclear energy or power spacecraft. Winterberg was proposing pure deuterium micro-explosions. H/T Crowlspace and J Friedlander.

Wikipedia entry for Friedwardt Winterberg.

Friedwardt Winterberg (born June 12, 1929) is a German-American theoretical physicist and research professor at the University of Nevada, Reno. With more than 260 publications and three books, he is known for his research in areas spanning general relativity, Planck scale physics, nuclear fusion, and plasmas. "His work in nuclear rocket propulsion earned him the 1979 Hermann Oberth Gold Medal of the Wernher von Braun International Space Flight Foundation [highest award in astronautical research] and in 1981 a citation by the Nevada Legislature." Winterberg is well-respected for his work in the fields of nuclear fusion and plasma physics, and Edward Teller has been quoted as saying that he had "perhaps not received the attention he deserves" for his work on fusion. He is known for his ideas which lead to the development of GPS (Global Positioning system, his fusion activism, his first proposal to experimentally test Elsasser's theory of the geodynamo.


Standard fusion bombs use the Tellar-Ulam design, which were using fission bombs to trigger a fusion bomb.

The basic principle of the Teller–Ulam configuration is the idea that different parts of a thermonuclear weapon can be chained together in "stages", with the detonation of each stage providing the energy to ignite the next stage. At a bare minimum, this implies a primary section which consists of a fission bomb (a "trigger"), and a secondary section which consists of fusion fuel. Because of the staged design, it is thought that a tertiary section, again of fusion fuel, could be added as well, based on the same principle of the secondary. The energy released by the primary compresses the secondary through the concept of "radiation implosion", at which point it is heated and undergoes nuclear fusion.


Super Marx Generator Ignition for Nuclear Fusion Power
Proposed use of a super Marx generator to ignite a pure deuterium thermonuclear micro-explosion. In a super Marx generator, N Marx generators charge up N fast capacitors FC to the voltage V, which switched into series add up their voltages to the voltage NV. The proposed super Marx generator can reach what nature can do in lightning. The high voltage in natural lightning is released over a distance about 1 km, and the same is true for the super Marx generator.



A “super Marx generator” ultimately reaching gigavolt potentials with an energy output in excess of 100 megajoule. An intense 10 million Ampere-GeV proton beam drawn from a “super Marx generator” can ignite a deuterium thermonuclear detonation wave in a compressed deuterium cylinder, where the strong magnetic field of the proton beam entraps the charged fusion reaction products inside the cylinder.

While the ignition without fission of a deuterium-tritium (DT) thermonuclear micro-explosion has not yet been achieved, the ignition by a powerful laser beam seems possible in principle. But it is unlikely it will lead to a practical inertial confinement nuclear fusion reactor, because of the intense photon burst of a high gain micro-explosion (required for a inertial confinement fusion reactor), is destroying the laser. Ignition is also likely possible with intense GeV heavy ion beams, but there the stopping of the beam in the target is a problem. In either case, 80% of the energy released goes into the 14 MeV neutrons of the DT reaction.

DT inertial confinement fusion is likely a hybrid fusion-fission reactor, with fusion providing the neutrons and fission the heat. It favors inertial fusion by encapsulating the DT “pellet” in a U238 or Th232 shell.














Deuterium Micro-explosive Space Propulsion
For a propulsion system to transport large payloads with short transit times between different planetary orbits: a deuterium fusion bomb propulsion system is proposed where a thermonuclear detonation wave is ignited in a small cylindrical assembly of deuterium with a gigavolt-multimegampere proton beam, drawn from the magnetically insulated spacecraft acting in the ultrahigh vacuum of space as a gigavolt capacitor. Note: This paper was presented in part at the NASA-JPL-AFRL 2008 Advanced Space Propulsion Workshop.

With no deuterium-tritium (DT) micro-explosions yet ignited, the non-fission ignition of pure deuterium (D) 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 D explosion. There the driver energy, but not the driver may be rather small.

Winterberger claims that the generation of GeV potential wells, made possible with magnetic insulation of conductors levitated in ultrahigh vacuum, has the potential to lead to order of magnitude larger driver energies. It is the ultrahigh vacuum of space by which this can be achieved. And if the spacecraft acting as a capacitor is charged up to GeV potentials, there is no need for its levitation.

The spacecraft is positively charged against an electron cloud surrounding the craft, and with a magnetic field of the order 10,000 Gauss, easily reached by superconducting currents flowing in an azimuthal direction, it is insulated against the electron cloud up to GeV potentials. The spacecraft and its surrounding electron cloud form a virtual diode with a GeV potential difference. To generate a proton beam, it is proposed to attach a miniature hydrogen filled rocket chamber R to the deuterium bomb target, at the position where the proton beam hits the fusion explosive. A pulsed laser beam from the spacecraft is shot into the rocket chamber, vaporizing the hydrogen, which is emitted through the Laval nozzle as a supersonic plasma jet. If the nozzle is directed towards the spacecraft, a conducting bridge is established, rich in protons between the spacecraft and the fusion explosive. Protons in this bridge are then accelerated to GeV energies, hitting the deuterium explosive. Because of the large dimension of the spacecraft, the jet has to be aimed at the spacecraft not very accurately.

Deuterium Micro-explosive Space Launch Systems
For a cost effective lifting of large payloads into earth orbit: the ignition is done by argon ion lasers driven by high explosives, with the lasers destroyed in the fusion explosion and becoming part of the exhaust.

If launched from the surface of the earth, one has to take into account the mass of the air entrained in the fireball. The situation resembles a hot gas driven gun, albeit one of rather poor efficiency. Assuming an efficiency of 10%, about 100 kiloton explosions would be needed to launch 1000 tons into orbit. It would be a cleaner and more public relations friendly version of the Orion Nuclear Pulsed Propulsion system.

Winterberg suggests an ultraviolet argon ion laser is used as a trigger. However, since argon ion lasers driven by an electric discharge have a small efficiency, he suggested a quite different way for its pumping.




where the efficiency can be expected to be quite high. As shown above, it was proposed to use a cylinder of solid argon, surrounding it by a thick cylindrical shell of high explosive. If simultaneously detonated from outside, a convergent cylindrical shockwave is launched into the argon. For the high explosive one may choose hexogen with a detonation velocity of 8 km/s. In a convergent cylindrical shockwave the temperature rises as r -0.4, where r is the distance from axis of the cylindrical argon rod. If the shock is launched from a distance of ~1 m onto an argon rod with a radius equal to 10 cm, the temperature reaches 90,000 K, just right to excite the upper laser level of argon. Following its heating to 90,000 K the argon cylinder radially expands and cools, with the upper laser level frozen into the argon. This is similar as in a gas dynamic laser, where the upper laser level is frozen in the gas during its isentropic expansion in a Laval nozzle. To reduce depopulation of the upper laser level during the expansion by super-radiance, one may dope to the argon with a saturable absorber, acting as an “antiknock” additive. In this way megajoule laser pulses can be released within 10 nanoseconds. A laser pulse from a small Q-switched argon ion laser placed in the spacecraft can then launch a photon avalanche in the argon rod, igniting a DT micro-explosion.




SCIENCE FICTION SIMILARITY
Science Fiction and technology futurists have always been interested in ways to enable high performance nuclear spacecraft. A classic in science fiction is Keith Laumer's bolo Supertank which had the Hellbore cannon, which has similarities to the proposed fusion system.

Hellbore ammunition consists of slivers of highly-pressurized frozen deuterium which, when fired, are ignited (by a laser) in a fusion reaction. The resulting bolt is contained and directed using strong magnetic fields in the breech and barrel. The resulting plasma travels at a considerable fraction of light speed. Since the Hellbore was designed as naval armament for Concordiat vessels, modifications had to be made to use them in an atmosphere to avoid losing a significant portion of the shot's energy to dispersal. To this end, a fraction of a second before using the Hellbore a powerful laser will be firing to create a momentary vacuum along the path of the bolt. Later Bolo marks are capable of internally manufacturing Hellbore rounds, using water as a raw material, whereby the deuterium isotope of hydrogen is separated and cooled cryogenically into splinters of frozen hydrogen. The Mark XXXIV carries a variant of the Hellbore known as the Hellrail, an anti-starship railgun weapon, possessing an output of 90 megatons per shot. Hellrails are designed for planetary defense and cannot normally be depressed to strike ground targets.


Winterberg page at University of Nevada

Dr. Winterberg obtained his Ph.D. under Dr. Werner Heisenberg, and is listed as one of the four notable students of Werner Heisenberg on Heisenberg's 'Wikipedia entry, along with Felix Bloch, Edward Teller and Rudolph E. Peierls.

His thermonuclear microexplosion ignition concept was adopted by theBritish Interplanetary Society for their Daedalus Starship Study.

Among many seminal papers:
Theory of Nerva Type nuclear fission rocket reactors. 2nd United Nations Conference on the Peaceful Uses Atomic Energy, A/Conf.15/P/1055, Geneva 1958; also translated into Russian under "Selected Reports of Non-Soviet Scientists", Moscow, Atomizdat 3,453 (1958).

First proposal for Impact Fusion Z. Naturforsch. 19a, 231 (1964); Magnetic macroparticle acceleration for impact fusion, J. Nuclear Energy 8, 541 (1966).


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