Homepage Forums Lawrenceville Plasma Physics Experiment (LPPX) Achieving greater plasma density

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  • #1734
    AvatarEngineer
    Participant

    I have heard Mr. Lerner say many times that ‘all we have to do is increase density’ of the plasma. How is this done, reliably? I have a few ideas, like increasing the ionization of the plasma to encourage pinch. Also, encouraging the contents of the plasma to contain less B10 and more B11. Is the plasma generator one of those that are used in accelerators for ions? I have seen concepts such as helion wave plasma generators that also achieve a high degree of ionization. Should the vacuum chamber also be positively charged?

    #13869
    AvatarNomme
    Member

    Just wanted to bump this because ‘Engineer’ posts a good question about increasing the density of plasma.

    #13870
    BreakableBreakable
    Keymaster

    It is quite simple – increase the current and you will get higher density. Now the trick is that increasing current causes breakdown of current carrying surface and that contaminates plasma with materials from cathode (or anode?). So there needs to be a way to prevent it. Initial plan was to use pre-ionisation to deal with that and AFAIK researching that is in progress.

    #13871
    AvatarEngineer
    Participant

    I hope that contact ionization is adequate for borane derived plasma.
    If not, more complicated methods will be needed. Has there been work done to show this?

    #13872
    Avatarmcjh
    Member

    So I have done a bit of reading – certainly not exhaustive – and this is the first I have heard of using Borane (BH3?). Wouldn’t triborane (B3H3) fit the fusion equation better? Is BH3 what has been used to date for pB11 fusion?

    #13873
    AvatarEngineer
    Participant

    Some things come to mind:
    Tri-borane is in a low valence state so easier to ionize.
    Borane is probably cheaper and more stable.
    If no isotope separation occurs for B11 before combination w/H,
    Extra B10 in tri-borane is wasted. Interestingly, borane is made by laser ablation of boron in hydrogen. The added step of laser isotope separation is obvious.
    Equal portions of boron and hydrogen assumes 100 % conversion. If excess ions are left, hydrogen is preferred, since it increases chance of boron collision.

    #13875
    AvatarIvy Matt
    Participant

    I believe the plan, at least initially, is to use decaborane (B10H14). Decaborane is a solid at room temperature, which enables safer handling before introduction into the chamber.

    The previous pB11 research that I am familiar with used either particle accelerators or lasers and solid boron targets.

    #13876
    Avatarmcjh
    Member

    Thank you for your answers.
    Since there is free H in the chamber, what is the relative probability of a p-p fusion compared to p-B11? I haven’t found any cross section data for these yet. Is there any neutron yield?

    Also, as I understand the reaction, it is

    p + B11 -> C -> 3He + 8.3MeV

    Not sure if the gammma number is right but is it actually emitted in the fusion to C? Is any energy released in the disintegration to He?

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