Homepage Forums After Fusion Can a Focus Fusion rocket engine take us to the stars?

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    This has spiked a great void that needs to be filled in me. Acheiving Fusion in Plasma!


    Fusion in plasma was achieved long time ago

    Now its time to make it profitable.



    Let me know if you want papers on the topic.



    At the bottom of wiki you will find relative links


    and other similar topics


    Having a large stationary laser with the ability to move the focus point based on the ground, and them create fusion under a lift vehicle could reduce the weight of the vehicle substantially. Only a small amount of h2 would be required to carry onboard the craft.



    Have a look at some of these links. Just get the gist of it and be awear of the scope with Z pinch.

    Plasma Z-pinch ads



    Like I said just get the gist of it.


    For greater thrust you could do what has been proposed for the polywell fusion call a quite electron discharge, which act by you dumping something in front of the particle beam and it would in effect blow it out the back of the ship for a lot of thrust, comparable to a rocket but of course the isp for what ever you dumping out wouldn’t be much better then a rocket.

    since space is filled with junk it wouldn’t be to hard to slow down in the asteroid belt, near a passing comet, or whatever and mine it a bit for the afterburner mix. this is basically the idea in a lot of since fiction books, 2001 a space odyssey just to name one.

    AvatarEvan Carew

    Using the below formula, if you consume 100Kg of fuel on a 2000 Metric Ton vehicle, you end up traveling
    .049 kps. This doesn’t seem to make sense. What am I doing wrong, or what is missing here? Is the exaust velocity an order of magnitude (or so) slow?

    Jolly Roger wrote:

    The maximum speed of the ship is not limited by the exhaust velocity as the action is relative… The speed limitation is mainly one of fuel, the ship will keep accelerating forever with infinite fuel and time, however as you approach the speed of light the net acceleration drops significantly as the relative mass increases.

    My Bad! Thank you. I stand corrected. I was assuming that the equation for final velocity was:

    Vf = Ve,

    where Vf is the final velocity and Ve is the exhaust velocity.

    The correct equation is:

    Vf = Ve * ln(Mi/Mf)

    where ln is the natural log, Mi is the initial mass of the ship, and Mf is the final mass.

    I will do some calculations with various mass ratios and post my results later.

    AvatarErik Boehm

    simulation11 wrote:

    Here is a site for scifi writers that has some interesting information.


    It states that we may expect a Hydrogen-Boron rocket engine to have an exhaust velocity of 980 km/sec, thrust of 61 kN and engine mass of 300 metric tons.

    We expect an FF engine to have a mass closer to 3 tons, but perhaps the other numbers are in the ballpark. If so, our spacecraft will have a top speed of 980 km/sec or 0.33% of the speed of light. I think that relativistic effects will be minimal.

    With a top speed such a small fraction of the speed of light, extra-solar missions will be limited to robots, sleepers or generation ships. However, it should do fine for getting around the solar system, even out to the brown dwarf, Barbarossa, thought by some amateur astronomers to be orbiting the Sun, currently at about 218 AU.


    The critical factor then is the thrust. At 61 kN, our 100-metric ton ship will have an acceleration of 61 cm/sec^2. It would hit top speed in a few weeks, but it would still take 13 months to accelerate, coast/cruise, and decelerate to Barbarossa. A larger ship, with the 2,000 ton mass of the Space Shuttle, would take 25 months for the same journey.

    The brown dwarf Barbarossa is not to be confused with the asteroid of the same name. Barbarossa may be the Dark Star Marduk/Nibiru that author Andy Lloyd is looking for.


    Thank u so much. It’s quite interesting info. Barbarossa, wow it is the same name with my sister. 😉

    simulation rachat credit

    It seems to me based on the Nomograms from that site:


    With Hydrogen-Boron Fusion, you could get to 1,300 km/s with a mass ratio of 4 (your ship weighs 4x as much when full of propellent, than when empty),
    Now given that the speed of light is 300,000 km/s, this is 0.43% the speed of light….
    Still not fast enough to colonize the galaxy in a short amount of time (23 million years to cross the galaxy?)
    Ignoring acceleration time, its still too long to make it to the nearest star in one life span.

    But….. if a focus fusion reactor capable of fusing hydrogen to Iron were developed, and a mass ratio of 10 were used, you could get over a third the speed of light.
    Just H->He fusion max, with a mass ratio of 8 (for comparison, the saturn V was 22), could get to 0.2 C, a fifth the speed of light, you could cross the galaxy in under a million years.
    Given the history of life on Earth (roughly 4,000 million years) in terms of the geologic timescale, colonizing the galaxy would take but the blink of an eye to a species that has mastered fusion.

    I’m not sure how those nomograms were generated.
    Especially the max values.
    Any reaction could get the highest possible “exhaust velocity” by just powering a big laser…
    Doesn’t use much propellant, but then what do you do with spent fuel? makes no sense to keep it, and it doesn’t make sense to jettison it/send it off at low velocity, when you dump all the energy into a huge laser.
    So I suspect that those values are calculated based on the maximum amount of extractable energy per unit weight of fuel, assuming all the extracted energy is used to accelerate spent fuel as propellant.

    If we can get proton boron fusion now, then in a millennia, with larger reactors, if we could get close to the maximum for H->He fusion, He could be all over the galaxy in a million years.
    as a species: 1 million years to reach earth orbit, another million years to reach the other side of the galaxy.

    Incidentally, the age of the earth, its lack of alien colonization, and the speeds at which fusion would allow travel, convince me that the “Rare Earth Hypothesis” is most likely valid.


    Evan Carew wrote: Using the below formula, if you consume 100Kg of fuel on a 2000 Metric Ton vehicle, you end up traveling
    .049 kps. This doesn’t seem to make sense. What am I doing wrong, or what is missing here? Is the exaust velocity an order of magnitude (or so) slow?

    the mechanics of your calculations are correct. with 100 kg of reaction mass and effective exhaust velocity of 1×10^6 m/s,

    Vf = Ve * ln(Mi/Mf)
    = 1×10^6 * ln( (2 x10^6 +100 ) / 2×10^6)
    = 49.99875 m/s

    what’s wrong is conceptual: rockets expel a huge amount of reaction mass. as much as 99% of their total mass may be consumed.

    as you can surmise, interstellar travel is infeasible unless/until an alternative to rocket propulsion is invented. since that appears to require new physics, it wont be happening any time soon on this planet.

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