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  • #1659
    Avatarael
    Member

    Hi there,

    I have a thought watching a youtube movie few days ago regarding fusion and got this concept question.

    It seems to be fairly easy to impart with linear accelerator energies in range of ~100keV to a positively charged particle and direct it against a target. However single particle collision are unsuitable to cause a nuclei fusion due to the very low nuclear fusion cross section comparing to that of Coulomb force. Basically particle scatters elastically losing their energy rather than fuse. In order to approach conditions favorable for fusion to take place the particle density and temperature needs to be maintain over the span of time. It seems to me that high speed collision of a small deuterium pellet (~50um diameter ?) travelling with the speed of 3100km/s and burring itself in the deuterium target might just create such condition. I reason that heat from collision will be unable to escape in the direction of the motion since collision takes place much faster than speed of sound which will limit as well heat losses to the sides. Basically the rate of heat delivery converted from kinetic energy could (??) out paste the thermal losses for a time long enough to support fusion. As a bonus no R-T instability as far I can see.

    – is there a FEA software that can simulate such things ? freeware hopefully.
    – have I missed something obvious ?

    thx

    #13585
    AvatarFrancisl
    Participant

    The closest research that I have found that is similar to your concept is the plasma railgun.

    #13586

    It’s like shooting one tiny drop against another and a bit bigger drop. Doesn’t much of the material just pass through. And even if it doesn’t I don’t think much of the kinetic energy will be released. The drop must be slowed down to a much lower speed if the kinetic energy is to be released. The slow down distance is very short. So I suppose that’s why you have to shoot from all direction simultaneously to make that happening. A cylinder of deuterium could if it’s long enough slow down the drop and release the kinetic energy, but the volume is too big and the heat would be spread in too much mass to reach high temperatures enough. So collision is possible but difficult.

    #13589
    Avatarael
    Member

    Francisl wrote: The closest research that I have found that is similar to your concept is the plasma railgun.

    I did some simplified and optimistic calculations and linear accelerator to get flake 50um in radius, 1um thickness to 1300km/s needs to be at least 100m long. Problem is that only small fraction of the atoms can be electrically charged (about 50ppm). Now I can see that accelerating plasmons lends to much more manageable equipment size.

    #13590
    Avatarael
    Member

    Earl of Plasma wrote: It’s like shooting one tiny drop against another and a bit bigger drop. Doesn’t much of the material just pass through. And even if it doesn’t I don’t think much of the kinetic energy will be released. The drop must be slowed down to a much lower speed if the kinetic energy is to be released. The slow down distance is very short. So I suppose that’s why you have to shoot from all direction simultaneously to make that happening. A cylinder of deuterium could if it’s long enough slow down the drop and release the kinetic energy, but the volume is too big and the heat would be spread in too much mass to reach high temperatures enough. So collision is possible but difficult.

    tiny pellet hitting other tiny pellet will not pass through since atoms are packed in solids at typical distances of something like 0.3nm. You probably refer to plasma and gasses collisions with much larger inter particle distance. I expect rapid de-acceleration and instant conversion of kinetic energy to heat. I was initially thinking that you need to shot from all directions (4 in tetrahedron configuration at least) to prevent momentum to escape, but then realized that this is a problem only if collision takes place at the speeds comparable to speed of sound in the material (like fission bomb implosion). If however speeds are > 100 times larger then heat escape is much slower then energy delivery. In first approximation, since material temperature goes up and heat moves out faster. Example: leading edge in supersonic plane is not transferring heat to the air ahead of the plane. If the impact area has no time to expand the volume is constrain too.

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