The spectacularly-named physicist Friedwardt Winterberg of the University of Nevada has long studied nuclear propulsion and nuclear explosives. He has just published a paper describing a nuclear explosive that uses chemical explosives (HMX, specifically) to drive a Deuterium-tritium fusion reaction, without the use of a fission element. If it could be made to work, it would result in a nuclear explosion  with very little in the way of radioactive fallout… no radioactive heavy elements, mostly just a giant BANG and gamma rays, X-rays and some neutrons. Nothing you’d want to stand too close to, but also nothing that would cause any real environmental harm.

The explosions themselves are not described as being particularly spectacular by H-bomb standards. A sphere of HMX 60 centimeters in diameter, with a chemical yield equivalent to about 1/4 of a ton of TNT, would set off a small core of liquid D-T, producing a nuclear yield of about 25 tons of TNT (0.025 kilotons). By enriching the outermost 1 cm of the high explosives with 20% boron, the bulk of the neutrons generated by the fusion would be captured; the boron itself would explode due to the sudden addition of the neutron energy, sending a shockwave inwards which would aid in burning the D-T. Theoretically the radius of the high explosive could be reduced by about half and would still produce the same nuclear BANG. So a thirty-centimeter (11.8 inch) diameter ball would produce a 25-ton explosion… a gain of a factor of about 1000 from the yield of the chemical explosive alone.

Winterberg suggests using these devices to generate electrical power in MHD generators 60 meters in diameter. But their utility for space propulsion seems fairly obvious. Given the  spherical nature of the bomb and the resultant blast, these would seem to be perfect fits for Johndale Solems “Medusa.” They would also work for propulsion systems with parabolic “pusher plates,” though the structures would have to be either very rugged, or (like Medusa) extremely flexible, or equipped with extremely powerful magnetic fields. For use in a more conventional Orion vehicle, something would have to be done to turn them into more effective shaped charges. Perhaps wrapping them in carbon fiber or graphene cylinders… hmmm…

  • Nick P.

    One wonders if they could be staged to make bigger booms, much like how ‘normal’ nuclear weapons are.

    • Anonymous

      From the sounds of it, it sounds kinda unlikely, but I suppose it’s possible. Run a real narrow thin-walled cone of depleted uranium into the D-T “pit” and fill with Lithium Deuteride or liquid D-T… maybe it would go off.

      I also wonder oif maybe HMX could be manufactured with deuterium and tritium in the interstitials, and whether that would booster performance. I kinda doubt it, though.

      • Nick P.

        Well…

        DT fusion as noted tends to put of a large quantity of rather lively neutrons, so I guess if you wrap the whole shebang in uranium you’d expect a fair bit of it to be fission’d by the fast neutrons.

        There’s a bit of symmetry to that which pleases me on some level, early nuclear weapons had their yields boosted by the fusion of deuterium and tritium introduced into their cores, and pure fusion weapons could possibly have their yields boosted by the fission of uranium on the exterior of the device.

        Thus the circle of life is complete.

        Furthermore if it’s putting out a bunch of gamma and x-rays it seems like the classic cylindrical Teller-Ulam configuration might still work with some tweaking, this device taking the place of the primary.

        • Anonymous

          Wrapping it in uranium would reflect the neutrons back in so that they can keep the temperature and pressure up, as well and bang around in the plasma. But the idea here is to wrap it in boron which will *absorb* the neutrons, They don’t get reflected back in, but as the boron absorbs the neutrons it *explodes* like really, really impressive chemical explosives, adding mechanical compression to the core, keeping the fusion process going for a few microseconds longer. Completely different mechanism results in similar outcome. However: boron is relatively cheap compared to uranium, doesn’t weigh a lot, and makes less of an environmental mess. Plus, the PR value of boron over uranium shouldn’t be ignored. Plus^2, nobody loads anti-tank shells with depleted *boron,* so the uranium can be reserved for conventional whoopass roles.

          • Nick P.

            For hypothetical purposes I’m disregarding PR and trying to get the biggest boom.

            Sure, boron would absorb the neutrons and go boom.

            But U238 will fission a significant portion of the time under fast neutrons and I’m forced to assume that would likely result in a larger boom than boron.

            Remember, this is something they already do on nuclear warheads. Tsar-Bomba would have been 100 megatons rather than 50 if not for them switching the second stage tampers to lead.

            And uranium is pretty cheap also.

          • Anonymous

            If your goal is “atomic bomb,” then there are probably better ways of going about jacking up the yield. But if you’re after “electrical power generation” or “spacecraft propulsion,” then eliminating uranium is a pretty snazzy development.

            The total energy of one of these things is about 25 tons = 10^18 ergs = 100,000 MJ. A powerplant that operates at a pulse rate of 1 per second – a good rate for a pretty sporty small Orion vessel – would of course generate 100 gigawatts. That ain’t too shabby, for the expenditure of a few dozen pounds of HMX, D-T and boron per second. Cleanup would involve some boron recovery, I imagine. But if there was substantial uranium needed per shot, things would get spendy in a hurry.

          • Nick P.

            If my goal was “electrical power generation” sure but I was just aiming for the biggest boom this system could deliver.

            As it is my custom.

            So we don’t misunderstand each other, yes as presented this system sound perfect for Orion type propulsion and the like, I never said it wasn’t.

          • publiusr

            What about a traveling wave?

            Land on an asteroid, and dug a tunnel. Ave a modified tube of these bomblets in a row. Could the reaction be delayed to give a more rocket like shove?

          • djolds1

            In terms of nuclear explosives, the interest of this concept is not how to engineer the biggest boom, but if this could be used to replace the usual weapons-grade fissionables primary and then daisy-chain up to “usual” thermonuclear yields via the Teller-Ulam stack. If that is possible, nonproliferation has a serious problem. Highly enriched uranium or weapons-grade plutonium are hard to acquire; simple uranium or thorium metal for pusher/tamper layers are easy.

            If the interest is power generation, Winterberg alone has cooked up far more sensible inertial-fusion reactor designs over the years – the high explosives wrap around the DT is a waste of mass and volume.

        • me

          The Air Force, Westinghouse, and General Electric are way ahead of you.

          The “H-bomb” has always been a uranium burner: energetic neutrons from D-T fusion split U-238 atoms, which fission energetically but cannot sustain a chain reaction because the neutrons they give off aren’t energetic enough. Without the uranium outer shell, much of the bomb’s energy output is energetic neutrons: a “neutron bomb.”

  • http://www.facebook.com/people/Kelly-Starks/1457062060 Kelly Starks

    Interesting. Plus side, Orion space craft can be much smaller, cheaper, and cleaner.

    Negative side, all efforts of stoping nuclear proliferation are based on containing Uranium enrichment tech to prevent the A side of bomb building. With this you can skip that and for similar levels of design effort skip straight to mini or maxi H-bombs.

    Eiather way – very enabling technology.

  • Peter Hanely

    “Then, just prior to the ignition of the high explosive, a 10^6A – 25MeV relativistic electron beam lasting 2×10^-8 sec and drawn from a Marx generator is shot through the pipe ” producing an intense magnetic field necessary to for the fusion ignition to work in the small package with the limited energy from the chemical explosive charge.

    Sounds like a fair amount of equipment besides the bomb charge itself, not consumed with the charge. Workable for a power plant or a spacecraft, not so practicable for a weapon.

    • Anonymous

      A lot of Great Big Devices can be made quite small if you only want to use ‘em once. One wonders how small and cheap an e-beam generator could be made if it was made to explode. Power it with actual explosives, and you’ll have the awesomest of bombs.

  • peter mueller

    It is possible to stage the devices (if they work) and build big orion related space ships:

    http://monstermaschine.wordpress.com/2012/10/11/flying-platforms-with-nuclear-pulse-propulsion/#more-3394

    or to do many, many other good things:

    http://monstermaschine.wordpress.com/2012/09/25/why-mankind-must-not-fear-the-pure-fusion-bomb/

    But of course there is still a certain (rather small) danger of nuclear proliferation.

  • Rick

    so a device the size of a basketball will blow with the force of 25 tons of TNT with an accompanying “bonus” lethal halo of hard radiation?

    And government/anti-defense people have been saying the “suitcase” or man-portable nuke was theoretically impossible. How much would this thing weigh? Without a fissionable initiator, is it radioactive enough to be detected from a distance? can it be carried in by an individual coyote or his clients?

    • Anonymous

      > How much would this thing weigh?

      Rather a lot. At 15-cm radius, and 1.91 gm/cm^3 (bulk density of HMX), that’s right at 27 kilograms. Doesn’t count the structure needed to hold it together or the equipment needed to generate the magnetic field.

      As for detection: there’s a core of liquid D-T. Tritium is a beta emitter, which would be easily blocked by the shell of HMX (not to mention any other shielding it might have). So I’d think that a bomb like this would appear pretty radiologically inert. The HMX, though, might set off a whole lot of detectors.

      • Rick

        my concern was using the various radiological scanners used at shipping ports and sometimes deployed along the southern border. If you’re close enough to a target to use a chemical sniffer, you’ve already nabbed the “undocumenteds” or drug dealers visually. You aren’t gonna trigger any detection at distance unless you get a lucky wind.

        I’m thinking interesting setup for a wargame scenario or such.

  • Anonymous

    The electrostatic fusion machine has already met all the requirements to overcome the Coulomb barrier. http://youtu.be/ro5-QYqqxzM

    • Peter Hanely

      Fusion is easy. Enough fusion to cover the costs of your driver is a bit harder.

      • Anonymous

        Indeed, under correct conditions, fusion is pretty easy. Superconducting magnet can produce very strong magnetic fields with low-power consumption, almost no loss of energy, and costs about $500,000.

  • djolds1
    • Anonymous

      Produced so far in milligram quantities. One of the issues with using these small nukes for power generation is the cost of the explosives. Hexanitrohexaazaisowurtzitane is probably a little spendy.

      But if you *really* want to boost performance, you’d ditch these weenie chemical explosive and replace ‘em with something like metastable solid metallic hydrogen. With a theoretical energy release of 216megajoule/kilogram (compared to HMX = 5.7 Mj/kg), only 2.6 percent as much metallic hydrogen would be needed. With a density of about 0.9 gm.cm^3, this would mean that about 5.5% the volume of HMX, if converted to metallic hydrogen, should in principle do the job. Additionally, I would think that no boron would be needed: the hydrogen would itself absorb the neutrons, and would turn into a plasma that reflects a shock wave back in to the core for added ooomph.

      • djolds1

        Winterberg has also written on exotic explosives (though not “conventional” metastable Hydrogen, IIRC). Peruse arxiv.

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