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  • #1700
    meemoe_uk
    Participant

    http://lppfusion.com/ff-1-moves-toward-goldilocks-bake-out/
    Quite surprised and disappointed to read that after all these decades of refinement, the best focus fusion devices today are held together by soft plastic that degrades under gentle heating. I thought FoFu1 was made out of metal – highly durable metal. I might not be a PhD in focus fusion, but I can tell ya this for nowt : You can’t make your fusion devices out of soft plastics such as PVC and Mylar.
    It makes no sense which ever way I look at it. Try this way :

    All that time spent ordering an extremely specialized tungsten cathode…. yet not upgrading from soft plastics. That’s like ordering a gearbox made out of diamond and metallic-glass-composite for a car with paper wheels.

    I would have expected Lawrenceville to rip out the mylar as soon as it caused the current problem and replace it with a better plastic. But instead you’re talking about dropping the temperature of the bake out, so that replacement mylar sheets won’t be damaged ?
    Why is the mylar so precious that you have to keep it at all costs ( in this instance, to the detriment of a vital oxide bake out ), while even the centerpiece extremely specialized tungsten cathode is inherently earmarked for retirement.

    You say you are using mylar sheets as an electrical insulator, well I think nearly all plastics are good electrical insulators. Can’t you use a plastic with better heat resistance, e.g. a Polyetherimide or Polyamide-imide plastic?

    ” if any apparatus isn’t fit for the exercise, upgrade the appartus, but if the mylar isn’t fit for the excercise, downgrade the exercise “

    #13729
    Lerner
    Participant

    Mylar is a much better insulator than other plastics. Until we finish testing FF-1 and determine its maximum voltages, we need this material. Once we know that, we might be able in a future modification to replace it with a much more resilient material.

    #13736
    yempski
    Participant

    http://www.dupont.com/products-and-services/membranes-films/polyimide-films.html

    Kapton would be a far better choice than PET.

    I’m pretty sure that a terrific company like DuPont would donate all the film you need.

    #13749
    meemoe_uk
    Participant

    Thanks for fast reply. Please excuse the tone of that 1st post. I’m a big fan of your work on focus fusion, but I feel frustration at the reports over the last year which seem to be mostly a continuum of minor technical problems made slow to fix due to lack of resources.

    #13750
    Andrew Palfreyman
    Participant

    Any updates? Heard nothing for 10 weeks. Bake-out complete?

    #13771
    Andrew Palfreyman
    Participant

    Great to read about the latest, very significant progress!
    I shared the excellent pic.
    Fingers crossed for a firing test which exceeds expectations.

    #13772
    Breakable
    Keymaster

    Not sure about it, but this is some comment we got on facebook:
    >I just read this: “According to DuPont the heat-induced shrinkage is caused by the relaxation of stresses imposed during manufacture.”
    >If this is true, wouldn’t an obvious solution be to pre-shrink a sheet of mylar at 150°C before cutting out the shapes you need for the device?

    #13840
    vansig
    Participant

    yes how did the bake-out go?

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