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  • #1460
    andrewmdodson
    Participant

    Many excellent papers here!!

    http://msnwllc.com/propulsion-publications

    http://www.aa.washington.edu/faculty/slough/

    I wonder if he would have any advice on pulsed power systems?

    #12609
    Ivy Matt
    Participant

    And some publicity here:

    http://www.washington.edu/news/2013/04/04/rocket-powered-by-nuclear-fusion-could-send-humans-to-mars/

    http://cosmiclog.nbcnews.com/_news/2013/04/05/17606782-scientists-develop-fusion-rocket-technology-in-lab-and-aim-for-mars

    From the Cosmic Log article:

    “The only answer to the ‘always 30 years in the future’ argument is that we simply demonstrate it,” Slough said. And that’s what he and his colleagues intend to do this summer, at their lab inside a converted warehouse in Redmond, Wash.

    The key experiments are due to take place starting in late summer, at the UW’s Plasma Dynamics Lab in Redmond. If everything works, that would give the researchers the confidence to scale up the laboratory apparatus. For example, they’d use lithium rings instead of aluminum rings to increase the efficiency of the reaction.

    #12629
    dennisp
    Participant

    So he’s expecting a fusion gain over 5 sometime around 2017, when they convert to D-T: https://s3-us-west-2.amazonaws.com/pnwmsnw/NIAC_PhaseII_FDR.pdf

    That should help funding efforts, if nobody else achieves it before then.

    And then a full-scale ground demo in 2020, a space mission a couple years later with a 40x gain, and 2030 for a manned Mars mission with a 200x gain.

    #12630
    Tulse
    Participant

    If they can get over-unity, it seems extremely perverse to me to focus on space propulsion rather than terrestrial power generation. The latter market is far far bigger, and the need is far far greater.

    #12631
    dennisp
    Participant

    Slough also started Helion Energy for power generation. They built a 1/3 scale device and last I heard needed $20 million for full scale. They just happened to get the NASA funding first.

    I’d bet that if they’re successful with the rocket design they’ll have little difficulty getting funding for Helion.

    On the other hand, fusion rockets would open up the solar system to large-scale exploitation and colonization, so the impact could be pretty major. (And of course focus fusion would make a nice rocket as well, perhaps better for really long trips since the exhaust velocity is so high.)

    #12632
    Tulse
    Participant

    I agree that fusion rockets are hugely important in the long-term, but if I were trying to create an actual company, the potential revenue for any reasonable time horizon is surely in power generation.

    #12633
    dennisp
    Participant

    No argument there. There’s definitely a business model for rockets, given SpaceX and the asteroid mining company, but for a while it’ll be nothing compared to the energy market.

    The one advantage of the space market is that you’re a lot less cost-constrained. Your super-high-performance rocket doesn’t have to be cheaper than burning coal. Helion doesn’t look terribly expensive but I haven’t seen estimates.

    I did just find out the exhaust velocity of this fusion rocket, NASA says about 30km/sec: http://www.nasa.gov/directorates/spacetech/niac/2012_phaseII_fellows_slough.html

    That’s a lot less than focus fusion, which according to some forum posts around here a couple years ago would be about 3% lightspeed if we just used the ion beam directly. Thrust would be lower since there’s a lot less mass involved.

    #12634
    Tulse
    Participant

    I would think the tremendous mechanical simplicity of FF would also be a huge benefit in space propulsion applications. Slough’s approach requires precise delivery of metal liners once every minute, which has to have a lot of mechanical overhead (in terms of complexity and weight), and introduces reliability issues. One of the beauties of the FF approach is how physically simple it is, with no moving parts apart from valves to deliver the fuel.

    I guess that if the issue is crewed applications, with the possibility of directly addressing mechanical problems by on-board staff, then the extra thrust is worth it. But I would think that FF would be ideal for robotic deep space exploration, with its potentially high Isp and reliability.

    #12635
    dennisp
    Participant

    Good point. Plus if you want more thrust you can mix in some reaction mass, maybe using the x-rays for preheating it.

    Some interesting links here: http://nextbigfuture.com/2010/03/dense-plasma-focus-dpf-fusion-systems.html

    #12638
    Breakable
    Keymaster

    Once you have clean/cheap/plentiful energy propulsion becomes not a serious problem. You can even produce and lift unreasonable amounts of chemical fuel up into orbit or you can produce anti matter and use that for propulsion:
    http://www.nasa.gov/exploration/home/antimatter_spaceship.html

    #12639
    benf
    Participant

    That’s really interesting, Breakable. Antimatter is highly unstable however and would be tough to use as a fuel. But maybe it’s something that could be combined with the DPF Fusion? Antimatter for initial boost followed up with DPF sustained output?

    I’m thinking there should be a heading for “Space Propulsion Technologies” within this Fusion Contenders section. It’s an important topic for discussion made more timely by this recent NASA Roadmap: In Space Propulsion on the subject.

    #12642
    annodomini2
    Participant

    Antimatter, while theoretically ideal for interstellar travel, currently isn’t practical.

    I’m not saying we won’t get there, but it’s a very far reaching goal.

    First we need a reliable (and CHEAP!) way to manufacture it.

    Then we need to be able to contain it for long periods of time. I believe the record is currently a few minutes.

    Then we need to have some mechanism that will use the energy from the reaction and convert it into propulsion.

    Anti-matter as a fuel is a long way off, unless several breakthroughs are made.

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