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  • #11067
    Avatarzapkitty
    Member

    opensource wrote: There seem to be some basics to straighten out here. Can you reply to my questions as well zapkitty?

    From the google tech talk: after losses (thermodynamic efficiency is estimated to be ~42%) the net output would be split thusly:

    x-ray over input .81
    beam over input .98
    x-ray + beam over input 1.79

    #11068
    Avataropensource
    Participant

    Sorry that’s not really what I’m asking, and I don’t really understand what “beam” stands for. My questions from post numbers 10 and 12 are what I’m trying to understand – sorry for being thick-headed.

    #11070
    Avatarzapkitty
    Member

    opensource wrote: Sorry that’s not really what I’m asking, and I don’t really understand what “beam” stands for. My questions from post numbers 10 and 12 are what I’m trying to understand – sorry for being thick-headed.

    Then the google talks video would be very helpful in that case.

    Very short version; A DPF produces a brief plasmoid. As this plasmoid collapses it emits a beam. In a Focus Fusion DPF the beam would be composed of helium nuclei, alpha particles, produced from the fusion of p and B11 in the plasmoid.

    This beam of fast-moving charged particles is electricity just waiting to be tapped.

    The plasmoid also produces x-rays, which again can be converted to electricity at high efficiency.

    And the plasmoid emits heat. 7-8 MWt at about 600 degrees wouldn’t be too great for spinning turbines but would be great for heating the neighborhood buildings in winter, endless applications as industrial process heat and also for evaporating seawater for desalination. If the heat is not wanted at all then it can be sent to an air-cooled heat exchanger.

    The energy total of everything else produced by the FF wouldn’t amount to very much compared to the beam, x-rays and heat.

    #11073
    Avataropensource
    Participant

    zapkitty wrote:

    Sorry that’s not really what I’m asking, and I don’t really understand what “beam” stands for. My questions from post numbers 10 and 12 are what I’m trying to understand – sorry for being thick-headed.

    Very short version; A DPF produces a brief plasmoid. As this plasmoid collapses it emits a beam. In a Focus Fusion DPF the beam would be composed of helium nuclei, alpha particles, produced from the fusion of p and B11 in the plasmoid.

    The energy total of everything else produced by the FF wouldn’t amount to very much compared to the beam, x-rays and heat.

    Vansig said that one-third to one-half of the total output is x-rays. Doesn’t this mean that the output in other spectra would be significant? How do I find the proportions of the various different types of energy outputs? Didn’t they place detectors in there when they were testing it (or is there enough known about this reaction that they could just know all the outputs and their relative proportions)?

    Also, are the x-rays all the same frequency? If not, then doesn’t this create an issue for capturing them. I take it this “pulse of charged particles” (loose language in my opinion) is mostly x-rays – but doesn’t it matter that they’re of variable energies? I have watched the Google Talk, but don’t remember seeing these sorts of specifics (or they were merely implied in physicist lingo which surpasses me).

    In theory, what charged particle or EM frequency would be the most ideal for converting into electrons using photo-voltaics?

    #11074
    Avatarzapkitty
    Member

    opensource wrote:
    Vansig said that one-third to one-half of the total output is x-rays. Doesn’t this mean that the output in other spectra would be significant?

    No. The x-rays are produced by a specific process in the plasmoid called bremsstrahlung and in an FF DPF plasmoid that process produces mostly x-rays. The specific energies of the x-rays generated are governed by the fuel, the temperature and the nature of the plasma confinement. The plasmoid is not a wide-spectrum energy source.

    If you are looking for energy to scavenge to achieve fusion then as far as FF DPF output power is concerned you would have the beam of charged particles, a pretty omnidirectional burst of x-rays and the heat. An FF unit would be very efficient.

    Will other things be produced? Yes, but not enough of anything to affect the balance of power.

    Bremsstrahlung, often referred to as “brem” or “brems” in fusion-speak 🙂 , actually cools the fusing plasma and is unwanted. It was initially supposed that brem losses would stop a DPF plasmoid from achieving a self-sustaining plasma burn, or “ignition”, and thus make practical DPF power generators impossible. But Lerner-hakase and company realized that the extreme magnetic field in a DPF core would be strong enough to cut down on brem losses… theoretically at least enough to enable a burn and move a practical DPF power generator from “impossible” to “perhaps feasible.”

    opensource wrote: How do I find the proportions of the various different types of energy outputs?

    If you are speaking of things that would affect the power balance, which is what I gathered from your questions, then it seems that you are looking for something that isn’t there.

    opensource wrote: Also, are the x-rays all the same frequency? If not, then doesn’t this create an issue for capturing them.

    The x-ray pulse would not be monochromatic but the spread of energy would be governed by the factors I noted above. And as the “onion” would have to be composed of many thousands of layers of metal foil to work it would, by its nature, be engineered to capture a wider spectrum than lower-energy photoelectric converters.

    opensource wrote: I take it this “pulse of charged particles” (loose language in my opinion) is mostly x-rays

    No, it’s a pulse of charged particles. In a beam no less 🙂 These would be alpha particles for the most part.The brem x-rays are an annoyance in that they have to be reduced as much as possible and what cannot be eliminated needs to be harvested.

    opensource wrote: In theory, what charged particle or EM frequency would be the most ideal for converting into electrons using photo-voltaics?

    side note: The onion is photoelectric in nature… photovoltaics are a branch of photoelectrics. Although I’ve made the error myself when speaking of FF it’s not quite the same thing.

    Ideal? From an FF? Converting the beam would be a few more percent efficient than converting the x-rays. The heat cannot be efficiently converted to electricity with current tech.

    #11075
    Avatardelt0r
    Member

    No. The x-rays are produced by a specific process in the plasmoid called bremsstrahlung and in an FF DPF plasmoid that process produces mostly x-rays. The specific energies of the x-rays generated are governed by the fuel, the temperature and the nature of the plasma confinement. The plasmoid is not a wide-spectrum energy source.

    Bremsstrahlung is the main source of xrays and is very definitely wide spectrum. There may be some line radiation from impurities, but this push the losses up massively and is typically avoided.

    The xrays are wide spectrum, there is no doubt about it.

    #11076
    Avatarzapkitty
    Member

    delt0r wrote:
    Bremsstrahlung is the main source of xrays and is very definitely wide spectrum. There may be some line radiation from impurities, but this push the losses up massively and is typically avoided.

    Well, “not wide-spectrum” was in response to opensources question about whether, since the plasmoid emitted x-rays, if it also emitted spectra other than x-rays in quantities sufficient to affect the overall power output.

    delt0r wrote: `The xrays are wide spectrum, there is no doubt about it.

    And there we get into details of the onion… which is why I stuck to generalities 🙂 I do wonder how the magnetic quantum effect will affect the x-ray output spectra with pB11 but I guess we’ll have to wait and see…

    #11277
    Avataropensource
    Participant

    On Wikipedia, it says, “If the plasma is optically thin, the bremsstrahlung radiation leaves the plasma, carrying part of the internal plasma energy.” Does this mean that if it is made to not be optically thin, that bremsstrahlung cooling won’t occur?

    #11280
    Avatarzapkitty
    Member

    opensource wrote: On Wikipedia, it says, “If the plasma is optically thin, the bremsstrahlung radiation leaves the plasma, carrying part of the internal plasma energy.” Does this mean that if it is made to not be optically thin, that bremsstrahlung cooling won’t occur?

    How would you do that? In fusion “optically thin” is in reference to x-ray photons.

    #11282
    Avatarvansig
    Member

    opensource wrote:
    If about 1/2 of the energy from the fusion reaction is x-rays, then of what form is the rest of the energy?

    about half is the kinetic energy of the charged particles, and there is also remaining heat to dispose of.

    Furthermore, don’t the outputted x-rays vary widely in frequency?

    yes, though this will be pinned down somewhat by the powerful magnetic fields.
    the goal, with those, is to suppress high-energy x-rays.

    #11285
    Avataropensource
    Participant

    So if using x-rays forces us to work against the bremsstrahlung cooling effect in designing a DPF, then maybe we shouldn’t use x-rays? Have there been any clever proposals for dealing with bremsstrahlung cooling besides just scaling to work against it?

    #11286
    Avataropensource
    Participant

    Sorry; don’t know how a double post occurred. Please remove this post moderator.

    #11287
    Avatarjamesr
    Member

    opensource wrote: So if using x-rays forces us to work against the bremsstrahlung cooling effect in designing a DPF, then maybe we shouldn’t use x-rays? Have there been any clever proposals for dealing with bremsstrahlung cooling besides just scaling to work against it?

    “Using x-rays” is the wrong way to look at it. In any hot plasma the ions & electrons are bouncing randomly around (influenced by the local E & B fields) – whenever an electron is scattered through an appreciable angle a photon is created with an energy corresponding to the change in momentum of the electron. This ‘breaking’ radiation is Bremsstrahlung, and if the electrons are at keV sized energies then the resultant photons are in the x-ray portion of the EM-spectrum.

    X-rays cannot be avoided. If you want a hot, dense plasma it will radiate away a proportion of that energy – the hotter it gets the faster it radiates, making it hard to achieve the temperatures required for fusion. The recent x-ray measurements implying a rough 400keV electron temperature suggest FoFu-1 is achieving a sufficiently rapid pinch to heat the plasma faster than it can cool.

    Since the proportion of fusion energy released and transferred to the ion & electron beams when the plasmoid collapses can never be enough to achieve nett energy gain, some of the energy lost from the plasma in x-ray radiation will need to be captured as well.

    #11303
    Avataropensource
    Participant

    Thanks James, you always clear things up…
    Can some gas be used to slow the x-rays to decrease reactivity and cooling?

    #11304
    Avatarjamesr
    Member

    opensource wrote: Thanks James, you always clear things up…

    Glad to be of service…

    opensource wrote: Can some gas be used to slow the x-rays to decrease reactivity and cooling?

    X-rays always travel at the speed of light, c.

    To have a chance for a significant proportion of the X-rays be re-absorbed by the plasma before leaving it you need something the size of a star (well not quite – but you get the idea)

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