Viewing 7 posts - 16 through 22 (of 22 total)
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  • #5912
    Aeronaut
    Participant

    Brian H wrote: Do the pins not have something to do with the formation of filaments? Perhaps they become disorderly if a cylinder is used, or don’t form at all. (Just a WAG).

    The pins would definitely have a lower total inductance than 1 ring, hence faster rise time.

    #5913
    Rezwan
    Participant

    There’s a published article on the effect of cathode structure on neutron yield performance in our very own denseplasmafocus.org website.

    The “squirrel cage cathode” is the type with bars/pins/rods, whatever you’re calling them. (Why “squirrel”?)

    The rods are more useful than the cylinder for neutron yield. Eric explained this to me using the words “magnetosonic shockwave”. Something about the plasma sheath moving faster than sound.

    I am unable to explain this to anyone else, which leads me to conclude that I didn’t fully understand.

    #5917
    Aeronaut
    Participant

    Rezwan wrote: There’s a published article on the effect of cathode structure on neutron yield performance in our very own denseplasmafocus.org website.

    The “squirrel cage cathode” is the type with bars/pins/rods, whatever you’re calling them. (Why “squirrel”?)

    The rods are more useful than the cylinder for neutron yield. Eric explained this to me using the words “magnetosonic shockwave”.

    I am unable to explain this to anyone else, which leads me to conclude that I didn’t fully understand.

    The Lee Model (a simplified and much easier to grasp description of how DPFs work) explains the axial phase (runout) as a porous current sheath driving a shock wave ahead of it. The next 4 phases of a cycle deal with radial inward shock wave, it’s reflection when it hits the centerline (more or less), and is then expanded to full width (not quite sure what that is in our squirrel cage, but it sounds like a solid cathode could set up a second reflected shock wave.

    Whether the second reflected shock wave would help or hinder the plasmoid is beyond my understanding of these things. in the first three phases, the shock wave jacks the temperature around 2:1…

    Hope this helps. And that someone else can make it a little clearer.

    #5918
    Brian H
    Participant

    Why would you want to maximize neutron yield? I can see it for fusion-thermal models like Tokamak, etc., but FoFu is Rezwan’s favorite word: “Aneutronic”! :cheese:

    Oops. After reading the referenced link, I see that the squirrel cage CUTS neutrons by a factor of 6. Sounds like a good deal, to me!

    P.P.S.
    A bit of research suggests to me that “squirrel cage” refers to a tall, narrow cage (since squirrels are big on vertical travel!).

    :smirk:

    P.P.P.S. See below. It’s an increase. I’m overdue for bedtime, it seems!

    #5919
    Henning
    Participant

    Brian H wrote: Why would you want to maximize neutron yield?

    Because that means you’re having more fusion:
    higher energy -> more fusion -> more neutrons

    This is a per fuel comparison. So possibly a mediocre DD shot yields more neutrons than a p11B shot with q>1 (big wishes here). So we’re using DD for seeing anything at all, and more neutrons for DD shots means more fusion.

    #5920
    Brian H
    Participant

    Henning wrote:

    Why would you want to maximize neutron yield?

    Because that means you’re having more fusion:
    higher energy -> more fusion -> more neutrons

    This is a per fuel comparison. So possibly a mediocre DD shot yields more neutrons than a p11B shot with q>1 (big wishes here). So we’re using DD for seeing anything at all, and more neutrons for DD shots means more fusion.

    Yes, obviously the neutron output is up 6x; I had it backwards, after I had it forwards. I had always assumed/known that with DD the n-count was used as an indicator of the intensity of the fusion event. All those lovely nasty double-down-quark baryons!
    http://hyperphysics.phy-astr.gsu.edu/HBASE/particles/parcon.html

    Attached files

    #12200
    Pete Keech
    Participant

    Very cool to see this concept has been revived in the latest design:

    http://lawrencevilleplasmaphysics.com/index.php?option=com_lyftenbloggie&view=entry&year=2012&month=03&day=23&id=61:machining-challenges-lead-to-new-cathode-design&Itemid=90

    When are the results going to start coming out on the “fusion crown”?

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