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  • #1126
    rashidas
    Participant

    Excuse my ignorance but is it possible to have miniature fusion? Just a few million atoms fusing together will provide all the energy needed for many applications. Any ideas?

    #10288
    Aquariumnerd
    Participant

    rashidas wrote: Excuse my ignorance but is it possible to have miniature fusion? Just a few million atoms fusing together will provide all the energy needed for many applications. Any ideas?

    i remember from physics that the energy gain by the nuclei is independent of distance between electrodes because force* distance=E. But the decrease in the distance is proportional to the increase in force, as f=e*Q and since e=v/d, e increases in proportion to distance decrease. Think of it like the plates of a capacitor. Therefore, as f=qv/d and E=f*d, The d cancels when a simultaneous equation is solved. E=fqv so the energy gain is independent of distance between inner and outer grid of the plasma chamber. I would have thought that micro fusion is possible. It seems rather logical :/ Creating a small driver circuit wouldn’t be hard at all. I suppose the hydrogen could be sealed up in the fusion chamber. A vacuum implemented in the manufacturing process. The difficult thing is harvesting the energy.
    e=electric field strength.
    f=force,
    q-charge on nuclei, which is two electrons charge or near enough.
    E is energy.
    I’m sorry to see no one else bothered to answer. Some people are so rude.

    #10297
    TimS
    Participant

    I think I read somewhere that Eric said making the focus-fusion device smaller was technically better, but that the electrodes needed to be a certain minimum size so they are not damaged by the electro-magnetic forces on them during pinch, which limits shrinking the device. Someone more informed please correct me if I’m wrong.

    Also, the focus-fusion device actually IS pretty small. The reactor is about the size of a coffee can, if I am not mistaken. I am not sure what the size of the X-Ray capturing “onion” around it is projected to be. I think a big part of a real device is the shielding required by the radiation from the side reactions, which might not be reduced significantly for a lower power reactor because the side reaction radiation would still be the same type and energy, just with a lower count.

    I expect that the geometry of a focus fusion device and the temperature and pressure requirements for fusion ignition have a significant influence on the voltage and current required for pinch, no matter how much reactant is desired to be fused. The pinch voltage and current determine the input power. If this is the case and only a small amount of reactant were fused, the device would not achieve break even. To achieve a lower output one could run the device at a lower pulse rate, which would reduce the maintenance requirements, but I do not see how that would make the device significantly smaller.

    Other technologies than focus fusion would scale differently, but in general fusion requires a high enough temperature and density for ignition. For technologies I am aware of this requires significant energy, so they will not achieve break even without enough reactant. However, this argument does not apply to non-pulsed technologies such as Tokamak, which have their own problems if the device is too small.

    #10610
    delt0r
    Participant

    Lets run numbers. We don’t have to guess in physics. Well not with everything.

    Lets say we want 1W and assume we have 100% efficient fusion. Now lets also use the highest energy density fuel, DT fusion. We get 17.6MeV for a pair of atoms which is 2.8*10^-12 J. So for 1 W we need 7.2*10^11 atoms to fuse per second. In words that is 720 billion atoms per second. Millions will only produce mW to mu W.

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