Electron-assisted fusion

    Quote from Wyttenbach

    15'000'000 C seems to be very cold .. at least for the JET people...


    Yes, it is cold, unless one would like to build a reactor the size of a star.
    This is the major stumbling block that is not mentioned by proponents of Hot Fusion. The conditions in a reactor on earth cannot be like that of a star, so the reaction will have to be different in order to work on earth.

    Quote from Wyttenbach

    axil: One more: The surface temperature of the sun is 6000 C what is also more or less the light temperature me may see outside. If a Rossi meltdown did reach 6000C then we may very well understand the Lugano T-measurements...


    Rossi is not the only experimenter who has seen the LENR reaction reach Sun like temperatures. Fleischmann's reactor got hot enough to vaporize concrete.


    http://atom-ecology.russgeorge…/fleischmann-singularity/




    Tom Conover Reports:

    Quote

    I load the fuel mixture into a titanium or stainless steel tube, and my engineer friend (who does lots of work for the infamous medical company Medtronics) laser welds plugs to seal the tube. I have had about six sessions that my buddy witnessed results from my projects, and the very first one resulted in a temperature that my friend stated was likely to have been 3000 to 4000 F in temperature at the end, and melted down.

    Quote from padam73

    Put two nuclei at a distance of 1fm during a non-negligible time and the rate of fusion will be high. No need of 1000 times more energy as you suggest.


    Although the above is also true, I think you meant to say "Put two nuclei at a distance of 1pm during a non-negligible time and the rate of fusion will be high".

    The presence of large amounts of hydrogen inside the core of the sun is counterintuitive. The core of the sun should hold heavy elements like iron and nickel as has been assumed for the other planets. Iron will not produce a fusion reaction. Has someone worked out how big an iron core the sun might be expected to generate, and determine how that size would affect the nuclear fusion model that is generally accepted?


    The assumptions made about how the Sun works needs to all be revisited.

    @axil,
    I agree that the core of the sun should have significant amounts of iron, and a host of other elements. The standard solar system model requires this. The idea that a ball of light gasses gas alone could condense and become heavy enough to become a star is pretty far fetched in a system containing rocky planets.

    As energy production of most of stars seems well understood, they base on p+p, p+d fusion starting at a few million K by Gamow tunneling ... what are the responses of CF enthusiasts to the objection that fusion being still nonnegligible down to 1000K should dramatically change physics of stars?


    Is there any other way of defense than trying to rely on requirement of stable molecular bonds? - for which one possibility is electron bouncing between them on nearly a line, screening the Coulomg barrier.

    Quote

    If fusion is possible down to 1000K, why stars don't produce much more energy?


    I didn't fully understand the question in your first paragraph. But the reason given for this is that the pp reaction (not the pd reaction) has two steps, one of which involves the weak interaction:

    • p + p → pp (strong interaction)
    • pp → d + e+ + ν (weak interaction, extremely slow)

    The weak interaction serves as the rate limiting step which keeps the power density of a hydrogen burning star very low, and hence the fuel is consumed at a slower rate. No stable molecular bonds; indeed, no molecules or atoms. No obvious need for electron screening from this set of details alone. In the Physics Forums thread you started, there was a reply that suggested that electron screening contributes a small amount to the overall rate. Did the paper cited mention electrons confined to one dimension? I'm going to guess that it did not.

    Quote from Eric Walker

    The weak interaction serves as the rate limiting step which keeps the power density of a hydrogen burning star very low, and hence the fuel is consumed at a slower rate. No stable molecular bonds; indeed, no molecules or atoms. No obvious need for electron screening from this set of details alone. In the Physics Forums thread you started, there was a reply that suggested that electron screening contributes a small amount to the overall rate. Did the paper cited mention electrons confined to one dimension? I'm going to guess that it did not.


    Eric: I'm missing two more equations:


    1') pp --> p + p
    2') ppe --> pne + e+ +v


    The questions are the usual ones: What are the probabilities (transition rates) for both sides of the reaction pp <--> p + p? are they equal? (in a finite reservoir!)
    Does in 2' an external electron imply a negative/positive screening effect?

    Quote from Wyttenbach

    The questions are the usual ones: What are the probabilities (transition rates) for both sides of the reaction pp <--> p + p? are they equal?


    A diproton (pp) is not a bound state, and it quickly decays. With regard to pp ⟷ p + p, presumably the two directions are not equal, with a very slight preference for pp → d + e+ + ν, which, in that branch, consumes the two p's that would otherwise split apart, after which the d is quickly consumed. A comment on Physics Forums thread linked to above pointed to a paper that discussed a small screening effect on the overall reaction rate. I have not taken a look at the paper.


    At this point I do not think we have the basis for the suggestion of screening of the kind Jarek has proposed, where there are electrons confined along the line of sight between two protons.

    Quote from Eric Walker

    In the Physics Forums thread you started, there was a reply that suggested that electron screening contributes a small amount to the overall rate. Did the paper cited mention electrons confined to one dimension? I'm going to guess that it did not.


    At a stellar core density (about 150 g/cc), the opportunity for screening may be quite enhanced. Whether it becomes an important factor.... ?


    Another speculative contribution: Muonic CF works because the greater muonic mass means the muonic orbital is about 1/207 of an electron. At a solar core density of 150 times water-- 1 g/cc at stp v. H2 0.0708 g/cc at stp-- 150/0.0708 at such a pressure suggests a volumetric compression factor of over 2100 times is likely. The cube root of 2100 is about 12.5 giving a mean estimate of the effect of solar core pressure on hydride radii of 1/12.5 or 8% of that at for liquid H2 at normal stp. For comparison, a Teller-Ulam thermonuclear device relies to great extent on compression of say lithium deuteride to 1000th of the volume at stp.....

    Eric, Gamow tunneling is in 3D, see e.g. slide 15 here: http://www.tunl.duke.edu/nnpss/lectures/17/UNC_2011.pdf
    I am currently reading "Nuclear physics of stars" book, but it will take some time.
    For this moment, my only objection is that, in contrast to Boltzmann distribution, tunneling is kind of a magical explanation - especially for nuclei, which are usually modeled with classical trajectories. This is a compact object which cannot just teleport through a potential barrier - we need a concrete mechanism for that.
    Indeed, in physicsforum there are cited papers that electron screening has minor effect - but they treat electron as probability cloud, which is great for dynamical equilibrium cases ... fusion is not.
    My point here is that asking for electron trajectory (averaging over a relatively long time to this probability cloud), there are trajectories remaining between the collapsing nuclei - screening the Coulomb barrier.
    That probability cloud is too blunt static tool for this subtle dynamical situation.


    Regarding my question, Gamow tunneling still weakens exponentially with low temperature - fusion still needs millions of Kelvins.
    If one believes in CF, tunneling is definitely not enough.
    Moreover, if proposing a CF mechanism, it should require a condition which is present in 1000K, but not present inside stars - otherwise their energy production, evolution should be drastically different (maybe it is - are there any arguments?)
    E.g. if one says 'hydrinos' or 'discrete breathers', he should also answer the question: why this explanation does not apply also to let say 100 000K region of the Sun?


    An example of such explanation (applying to 1000K but not 1MK) is requirement of stabilizing electron trajectory for molecular bond between two nuclei - in million kelvins fusion requires smaller assistance of electrons, but it's more difficult for fast electrons to find a stable trajectory between nuclei for the short moment of approaching to collision.


    Any other mechanisms which could grow in strength while lowering temperature?
    Or maybe you have seen some alternative models of stars - with included LENR?

    Quote from Jarek

    I am currently reading "Nuclear physics of stars" book, but it will take some time.
    For this moment, my only objection is that, in contrast to Boltzmann distribution, tunneling is kind of a magical explanation - especially for nuclei, which are usually modeled with classical trajectories. This is a compact object which cannot just teleport through a potential barrier - we need a concrete mechanism for that. ... That probability cloud is too blunt static tool for this subtle dynamical situation.


    Regarding my question, Gamow tunneling still weakens exponentially with low temperature - fusion still needs millions of Kelvins.
    If one believes in CF, tunneling is definitely not enough.


    Tunneling doesn't feel like a magical explanation to me. When it comes to nuclear processes, I think of the reactants (nucleons) more in the manner of EM radiation than particles. Protons and nucleons can "leak" through Coulomb potential barriers, in the way that EM radiation can leak through an imperfect Faraday cage. That's just how they behave. To this Feynman would say something like "we don't get to choose how nature behaves." You're trying to treat nucleons like billiard balls, which is possible to a certain extent, but is an imperfect model for anything but elastic scattering (and even then it conceals some interesting things that are going on).


    In fission reactors, 135Xe is a "neutron poison." Its neutron capture cross section is 2,000,000 barns, which is very high. Geometrically speaking, this means that the area of the cross-section is far, far larger than that of the actual nucleus which is presented to oncoming neutrons. I doubt this phenomenon can be understood in terms of classical billiard balls.


    About the Gamow tunneling weakening exponentially with low temperature — (1) the core of the sun is at 15M C, as you've pointed out; and (2) I see no reason to try to draw an analogy between processes in the solar core and LENR. But I do agree that if one is pursuing "fusion" as an explanation, things become problematic at ~ 1000 C in the way you point out. That's one reason I don't think fusion is a first order process in any LENR observations.

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