Just an idea:pellets of BEC as another parameter to optimize fusion in DPF

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  • August 17, 2010 at 5:58 pm #882
    Breakable
    Keymaster

    I just want to steal an idea from NIF and propose using of pellets that are pre-compressed or maybe even Boze-Einstein-Condensate pellets for each pulse in DPF.
    While it would complicate the vacuum chamber maybe the compression and closeness of atoms could provide better efficiency for pulses,
    similar like the hot water turns into ice easier than cold so maybe could the “condensated” atoms fuse more easily together.

    August 18, 2010 at 2:03 am #7771
    jamesr
    Participant

    I’m not sure where to begin with this – but, no…

    How can something be “pre-compressed”?? A Bose-Einstien condensate is by definition cold. It takes an enormous amount of energy to cool something so every atom is in it’s ground state. We want all the ions to have enough energy to overcome the coulomb barrier to fuse – you couldn’t get any further from this state as a BEC really.

    August 18, 2010 at 12:38 pm #7772
    Breakable
    Keymaster

    I am not a physicist, but please don’t dismiss my idea out of hand. Take a look at it this way:
    You have 2 parameters in fusion, pressure and temperature. AFAIK they are interchangeable – the more pressure you apply the less heat you need. I would think that the amount of gas used for each shot is pretty small (or otherwise the e=mc2 would blow up you building), so the heating requirements should be small. The pre-compression could be done in pellet or BOC form. The pellet outer layer serving as a container (like liquid gas canisters).
    I am not sure about the circumstances of the process, but:
    Heating it up could not be an issue with a lot of pulse energy going into heat and small amount of gas to heat.
    On the other hand, compression might be an issue, because you fill the whole vacuum chamber with loose atoms
    and you must capture enough of them during the pulse and then use the energy of the pulse to compress (the pulse should be affected [weakened] by gas pressure).
    Edit:
    So having the gas pre-compressed should weaken the pulse less. And BOC transition into fusion plasma could be pretty instantaneous
    without letting it separate the atoms to much.

    August 18, 2010 at 6:27 pm #7774
    jamesr
    Participant

    Sorry, I didn’t mean to be flippant (I had just come back from the Pub when I posted it).

    I assume you are suggesting if a pellet of fuel is inserted into the point where the colliding filaments normally form the focus. Whether the pellet is room temperature, frozen at a few Kelvin, or cooled further to near absolute zero to make a Bose Einstein condensate wouldn’t make much difference. The difference between 0.3, 3 or 300K and the 10^9K needed for fusion are all essentially 10^9K.

    pressure = n*T, where n is the number density. For fusion you need the triple product of n*T*confinement_time to be greater than a critical value (dependent on the reaction in question). You always need the temperature to be high enough for the reaction to happen at any appreciable rate. So it’s not as simple as increasing density so you can lower the temperature, generally though if you can increase density you can decrease the required confinement time.

    As for using the collapsing filaments of a plasma focus device to provide the energy to what is essentially inertial confinement fusion, instead of lasers is an interesting idea, but I think the axial symmetry of the plasma would mean the pellet would be compressed unevenly and squish out of the ends before it could be heated sufficiently.

    August 18, 2010 at 7:28 pm #7777
    Breakable
    Keymaster

    Thank you for understanding and considering the idea properly. I also wonder what would happen to the pellet during the pulse.
    Maybe it would be finely compressed,
    maybe it would need precise location and speed control,
    maybe it would need special form for pellet,
    maybe it would need ionization in some way.
    maybe the use of lasers to preheat it could resolve the squishing problem and that could result in a hybrid laser inertial dpf.

    Still we are at the birth of a fusion energy research field and I expect lots of mixing and matching from all the fusion concepts in all the design areas when we are further down the road:
    confinement, thermal management, radiation management, bremsstrahlung control, fuels, switches, capacitors …

    August 18, 2010 at 10:16 pm #7781
    Aeronaut
    Participant

    Breakable wrote: I expect lots of mixing and matching from all the fusion concepts in all the design areas when we are further down the road:
    confinement, thermal management, radiation management, bremsstrahlung control, fuels, switches, capacitors …

    Me, too.

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