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Fusion Beam
Using inertial confinement to produce spacecraft propulsion | |
(Disclaimer: I came up with this independently, then a quick Google showed there have been other expperiments in this direction. I believe my concept is different enough to stand on its own.)
<prelude; skip if you wish>
When I first learned about Project Orion (linky) many years ago,
I thought "there must be a better way" - it's like propelling your car with sticks of dynamite.
A few years ago, I was introduced to inertial confinement; using laser beams to stop particles cold.
Then I heard about the NIF (linky), using lasers to create fusion reactions.
</prelude>
The ideas of Project Orion and the NIF suddenly gelled in my mind: using lasers to create fusion explosions to propel a spacecraft.
One of the key components is the ShadowBuilt split-cavity laser (linky). The beam energy inside a laser cavity is far higher than that of the beam which comes out of the cavity, due to the 95% reflective mirror that lets the beam out. So if I use the beam while it's still in the laser cavity, there's more useable energy available.
The other important innovation is using palladium deuteride wire as the fuel. Palladium can absorb a massive volume of hydrogen or deuterium within its atomic structure; I'm not sure about degassing out in space, so maybe coat the wire in Teflon or something to help seal it (Teflon will help later too). Having it as a wire gives an easy method of feeding the fuel into the cavity.
The basic design (linky) is to put a series of split-cavity lasers around a ring, with a deflector plate in the centre to deflect the fusion explosion going on in the middle. Rather than the intermittent, large explosions of the Orion, the will be a (more-or-less) continuous small fusion blast going on to provide the propulsion. Having the palladium in there as well will add some extra mass to the expelled particles.
The 3 (probably, maybe more depending on space) rings of split-cavity lasers, possibly staggered (I thought of that after I built the CAD model) to fit better, would require large amounts of power - that's the main half-baked bit.
So; the lasers work continuously, as the palladium wire is fed through the 'spike' at the centre of the deflector into the point where all the beams cross over (it's at the laser waist, not a focal 'point' as such - minimum size depend on lens properties and beam wavelength). The palladium and its contained deuterium are 'crushed' by the beams, fusing and releasing large amounts of energy, which is mostly the kinectic energy of the fused particles (and the handy, heavy, hot palladium). This energy is transferred to the spacecraft (some directly, some via the deflector plate) creating acceleration - action/reaction and all that.
I'm not sure about the wire actually 'breaking' the laser beams; it may be more of a 'fast intermittent' instead of a 'continuous' process, as the lasers build up photons again.
Also, I have absolutely no sense of the scale of this thing - it could be the size of a car, but it could be the size of an olympic stadium.
ShadowBuilt Fusion Beam - the planets beckon...
Project Orion
http://en.wikipedia...clear_propulsion%29
Nuclear explosive propulsion [neutrinos_shadow, Feb 17 2011]
National Ignition Facility
http://en.wikipedia...l_Ignition_Facility
Inertia confinement experiments - huge lasers! [neutrinos_shadow, Feb 17 2011]
(?) Laser comparison
http://s1199.photob...Lasers.jpg&newest=1
Comparing a normal laser with the split-cavity laser [neutrinos_shadow, Feb 17 2011]
(??) Overall model of the FusionBeam
http://s1199.photob...onBeam.jpg&newest=1
A simple CAD model of the general idea [neutrinos_shadow, Feb 17 2011]
Scale demo using 3 lb. coffee cans of c4.
http://www.youtube....watch?v=E3Lxx2VAYi8
<aside> how come I never see mr. C Clarke in any other suit? [2 fries shy of a happy meal, Feb 19 2011]
(?) split cavity laser
http://s1199.photob...dia/Lasers.jpg.html
[beanangel, Oct 26 2016]
Boeing Patent, 2 years after this...
https://spectrum.ie...r-fusion-jet-engine
Bastards! [neutrinos_shadow, Feb 06 2023]
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I had a horrible foreboding that I was in for another novella-
sized [Vernon] posting, until I scrolled down. |
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The palladium bit is a nice touch - a nod to cold fusion
dreams of yore. |
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I'd not worry about the degassing, as the wire would only be outside the ship for a small amount of time. |
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I'd switch over to little pellets instead of wire, if you could. An electric pellet gun could place the bits in the right location. A wire feeder's end would have to be very close to the ignition point, as de-coilers (as they are called in industry) don't leave a nice straight wire. |
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I imagine a rather thin wire... wouldn't the heat of fusion tend to wreck it ? |
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Liquid would be neat and unlike pellets infinitely'ish variable. |
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/propelling your car with sticks of dynamite/ |
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When will there finally be some reduction of this concept to practice? |
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Why does this need to be pushing spacecrafts around? It sounds like this is a way to do fusion energy. Can't we have this in Topeka, powering our plasma TVs? |
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If you made the "chamber" perfectly reflective and a section of a sphere, you could get some of each blast to reflect off it and back onto the next pellet/droplet if timing was right. |
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If you make the blasts small enough and often enough, it becomes practically continuous. |
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Ooh, resonating spherical shockwaves - I like that! Maybe pulsed is better... |
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Beautiful.
//resonating spherical shockwaves // is setting off red flags for me. I'm not sure why, but I think you would want to throw in a spoiler-wave every so often to prevent resonance amplifying the wave to the point of vibrating the craft apart...sort of like having five prop blades rather than four. |
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I really like the Orion concept other than the fallout, how would this idea compare when it comes to radiation?
George Dyson's TED talk on Orion is good, and this [link] shows video of some of the scale model testing. (+) |
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// The palladium and its contained deuterium are
'crushed'
by the beams // |
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Without a hohlraum, what will do the crushing? I think if
you
want to add a hohlraum, it could be a continuous tube
surrounding the wire (probably actually two half-tubes
that
get put together inside the feeder, for practicality of
storage and feeding). |
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Also, a Google search for 'ShadowBuilt split cavity laser'
only leads back to this page. Is it another of your ideas,
which you have yet to write up? |
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Probably Shadowbuilt refers to his moniker. Like BUNGCO but more Sharper Image sounding. |
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That is very obvious now. I have no idea why I didn't see
that. |
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I would still like to see that split-cavity laser published. |
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[notexactly]; the split-cavity laser is something that came to me in parallel with the Fusion Beam. I didn't think it was complicated enough to warrant its own half-bake. I would like to rig up a test model (but I should have thought of that way back when I was studying laser physics at university; they had the toys to do so). |
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As for the hohlraum, my theory was that if I could get the photons dense and coherent enough, I could manage to achieve fusion without one. From my (brief) research, a hohlraum is not needed, but it does make things a lot better/more efficient.
The main purpose seems to be converting the laser (UV, IIRC) to x-rays, ie: getting the photons as energetic as possible. On-going research into x-ray and gamma-ray lasers will (hopefully) be combined with inertial fusion experiments; depends on the power requirements. |
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See linky for Boeings patent. There's even less detail than I've got here! Patent Office didn't care when I complained, & it's not worth fighting. If they DO (try) to actually do it, I'll quietly let all their competitors know that it's actually public domain & they can all freely have a go. |
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[a1], yes, that one. From 2015. 4 years after this post (not sure where I got "2 years" from...). |
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Funny how they shut me down for posting my own prior art here, after benevolently granting their one year grace period in lieu of our constitutionally protected first-to-invent right, yet deny your claim. |
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//filed in Oct 2012// Ah. That's where I got "2 years" from.
//more detail//
HA! You obviously didn't bother to read the "more detail". It repeats the same waffle about "at least one laser" several times, with tiny vague differences each time. There is a little bit extra about using a turbine to generate power from otherwise-lost heat (a reasonable idea but almost certainly not efficient enough), & a bit about using Uranium for the fuel pellets (which 2 of the referred patents are about). The other ref is about using a laser to heat air as a propulsion system (which has successfully been done); nothing to do with space craft or fusion.
Ah, just noticed: the 3 patents & all but 1 of the "other publications" are "cited by examiner" ie. not from Boeing.
A lot of these technology-type patents (especially from big companies) are deliberately ultra-vague, & submitted purely to (theoretically) block anyone else from going down the same path in the future. |
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