Low Energy Nuclear Reactions (cold fusion)

[Pincho Paxton]

Welcome to Sciforums.

No. In fact there are strong reasons to think it is impossible. To get two positive charged nuclei to fuse they much be placed essentially in contact where the "strong nuclear force" can over come the Coulomb force pushing them apart. Doing that is very hard - requires lot of energy as the Coulomb force increases quadratically as the distance between the nuclei is decreased.

I am too lazy to do a real example but guess that when they are separated by one nuclear diameter more than 10,000 pounds of force is resisting them moving closer together. That is why fusion is hot fusion. At a "million degrees" the random speeds get high enough so that a tiny fraction of the nuclei are both moving directly towards each other and happen both to be with exceptionally greater than the average speeds needed to overcome the Coulomb repulsion.

Summary: Chemistry ain't ever going to make energy via nuclear fusion. Only scam artists, dreamers and foolish investors think it might.

Yeah, I find your explanation interesting, it gives me something to work on.

[Billy T]

Billy T:

You forget about muon-induced fusion at room temperature. Lots of experimental evidence showing fusion can occur if the electrons are replaced with muons, shortening the atomic bonding distance between the nuclei. This brings the nuclei sufficiently closer together that significant fusion can take place. But it did not prove practical, due to the costs of muon production...

I am not much aware of this work. I assume it is only for H to H fusion. Is that correct? If two cold muon hydrogen atoms had nuclei closer due to being smaller, I would guess a huge amount of energy would still be required to bring their nuclei close enough to start to feel attraction -Is that not correct? Best bet I would guess would be if these muonic hydrogen were deuterium - trying to form He.

[Walter L. Wagner]

current research on muon-catalyzed fusion:

http://www.rikenresearch.riken.jp/eng/frontline/5976

wikipedia article as starting point: http://en.wikipedia.org/wiki/Muon-catalyzed_fusion

Steven Jones controversial figure: http://en.wikipedia.org/wiki/Steven_E._Jones

[Tronkostroglutegunkr]

Apparently, Rossi is sending a device to the University of Bologna to be independently tested. Just a rumor, but if true, it makes things even more confusing.

[kwhilborn]

Yes, and the University of Uppsala where the last test occurred.

I just googled "cold fusion"

results where an article on Andrea Rossi ecat on both MSNBC, and fox news.

even if it is just repetition of what we see here, the more people involved in this the sooner a concrete conclusion will be delivered. At least the main stream media is noticing. Finally!

[Tronkostroglutegunkr]

He's going to have to start getting some money out of this soon if it's a scam, because as the rich mainstream media get involved with all their resources the chances of him being revealed as a fraud only grow greater.

Go Rossi!

[Billy T]

... Go Rossi!

Where should he go? To hell or jail I think would be the appropriate destinations. (For reason stated in the one line summary of post 398.)

[quadraphonics]

So the concept of 'tweaking' the parameters for fusion at room temperature has been around for awhile. But I've not seen convincing methods of bringing the nuclei closer together, albeit for brief periods, other than the muon induction method.

There are a few other "room temp" fusion processes (see Wikipedia), but like muon-mediated fusion none of them produce a net energy gain.

One thing that occurs to me though - why wouldn't it work to just fuse neutrons onto nuclei, rather than trying to fuse multiple nuclei together? I.e., produce heavier isotopes of the same element, rather than heavier elements. I guess the binding energy calculations don't work out?

[Captain Kremmen]

Where should he go? To hell or jail I think would be the appropriate destinations. (For reason stated in the one line summary of post 398.)

Heh Heh

For various reasons, I think fraud is not the likely explanation.
But if he is found guilty of fraud, where better than the e-cat container as his prison?

[Billy T]

One thing that occurs to me though - why wouldn't it work to just fuse neutrons onto nuclei, rather than trying to fuse multiple nuclei together? I.e., produce heavier isotopes of the same element, rather than heavier elements. I guess the binding energy calculations don't work out?

I think your guess is basically correct (as all tautologies are). Here is some understanding of why:

If you look at the isotopes of any heavy element there are typically few stable ones in the middle of the mass range and then often even at the heavy end of the range (higher neutron to proton ratio) one or two unstable isotopes. For any given element the mutual electric field trying to explode it is balanced by the nuclear strong force of all the nuclear particles (neutrons + protons).

Thus one might think that you could have an unlimited number neutrons, but you can not. Exactly why, I am not sure, but part of reason is that the range of the nuclear force is very short - does not even "reach" across the nuclear diameter for heavy elements. This is why there is an upper limit to the table of elements. I.e. an outer proton only feels the attractive strong force from the protons near it but feels the Coulomb repulsion from ALL the protons in the nucleus.

There must be a net relatively weak repulsion between two neutrons - a pair of neutrons has a "negative binding energy" - does not exist. Thus adding too many neutrons to any given heavy element makes it unstable. Obviously not having enough makes it unstable too as then the Coulomb force does "blow it apart." There is a net attraction between a proton one or two neutrons (Deuterium and tritium do exist.)

I suspect that the "weak" net repulsion between two neutrons has a greater range than the nuclear strong force. Thus, if true, too many neutrons added to any heavy element nucleus would be feeling this longer range neutron/neutron repulsion after all the neutron/proton attraction was gone - I.e. the outer excessive neutrons would just be "blown off" even if one wandered close to the nucleus. - Why with flux of neutrons you can not artificially build heavier isotopes than exist in nature.

I don't know if all this is correct - I know little nuclear physic; but believe this is a self consistent model of reality. I am not even sure that the sum of individual forces (between two nuclear particles) is the net force acting as it is in classical macro-physics. I suspect it is not inside the nucleus, so there force analysis would be very complex (if it makes any sense at all).

PS: If we ever come to a planet which has only the heaviest stable isotopes, that would indicate they used your idea of getting energy by fusing neutrons onto the lighter isotopes. That evidence of a prior intelligent life form would last for billions of years - long after their ceramic toilet bowls had turned to dust.

[quadraphonics]

There must be a net relatively weak repulsion between two neutrons - a pair of neutrons has a "negative binding energy" - does not exist.

No, I do not think that is correct. The (residual) strong force is attractive between any combination of nucleons - neutrons are attracted to neutrons by the strong force.

Thus adding too many neutrons to any given heavy element makes it unstable.

My understanding is that this is caused not by any repulsion between neutrons, but by the fact that the protons end up farther away from one another, and so no longer within range of the strong force.

I suspect that the "weak" net repulsion between two neutrons has a greater range than the nuclear strong force.

Unless I've missed something fundamental, there is no repulsive force between neutrons.

Why with flux of neutrons you can not artificially build heavier isotopes than exist in nature.

That's a tautology - all of the heavy isotopes that exist in nature, were created exactly by neutron capture of such fluxes.

[Billy T]

No, I do not think that is correct. The (residual) strong force is attractive between any combination of nucleons - neutrons are attracted to neutrons by the strong force....

If that were true then with no Coulomb repulsion acting, two (or even larger numbers) of neutrons would bind together - Would exist, but they do not.

Hence there must be at least a net weak, repulsion between them as I said; not the attraction you claim exists.

[Walter L. Wagner]

If that were true then with no Coulomb repulsion acting, two (or even larger numbers) of neutrons would bind together - Would exist, but they do not.

Hence there must be at least a net weak, repulsion between them as I said; not the attraction you claim exists.

It would exist outside the 'sea of stability'; actually beyond the 'neutron drip line'. Highly radioactive, 'dripping' neutrons as it tended towards stability.

[Billy T]

It would exist outside the 'sea of stability'; actually beyond the 'neutron drip line'. Highly radioactive, 'dripping' neutrons as it tended towards stability.

Are you explaining anything, or just giving some names to what I said is true?

Your post reminds me of the doctor explaining why sleeping pills help you sleep. He said: "Sleeping pills make you sleepy because they contain a narcoleptic agent." If your post is any different than this doctor's "explanation" I don't understand how it is.

Also it is not clear to me what the initial "It" is referring too. Please edit and replace "it" by its antecedent. If your "it" is a neutron, then you are merely noting the fact that isolated neutrons are not stable but have a relative long half life. In your terms: They "dip into protons" with beta particle produced too, I think, but this "dripping description" does not explain why or how that happens, it just gives the fact a name, like the doctor's "narcoleptic agent." For example tells no reason why the neutron does not "drip way" when part of a nucleus.

[Walter L. Wagner]

Are you explaining anything, or just giving some names to what I said is true?

Your post reminds me of the doctor explaining why sleeping pills help you sleep. He said: "Sleeping pills make you sleepy because they contain a narcoleptic agent." If your post is any different than this doctor's "explanation" I don't understand how it is.

Also it is not clear to me what the initial "It" is referring too. Please edit and replace "it" by its antecedent. If your "it" is a neutron, then you are merely noting the fact that isolated neutrons are not stable but have a relative long half life. In your terms: They "dip into protons" with beta particle produced too, I think, but this "dripping description" does not explain why or how that happens, it just gives the fact a name, like the doctor's "narcoleptic agent." For example tells no reason why the neutron does not "drip way" when part of a nucleus.

The following article might help you refine your question:

http://cerncourier.com/cws/article/cern/31868

[Billy T]

To Walter: Thanks for the interesting reference, which begins with:
“…What combinations of neutrons and protons can form a bound nucleus? The long-elusive answer continues to stimulate nuclear physicists. Even now, decades after most of the basic properties of stable nuclei have been discovered, a fundamental theory of the nuclear force is still lacking, and theoretical predictions of the limits of nuclear stability are unreliable. So, the task of finding these limits falls to experimentalists …”

Who have drawn the dark line on the chart of the nuclei shown in this figure from your link:
and called it the “drip line.” It has only an observational basis and could equally well have been called the “black line” or the “isotope boundary line” – just a name, explaining nothing, and certainly has nothing to do with anything “dripping.”

The article does suggest that its regular steps may be related (in some not well known way) the even /odd alternation of the number of nucleons in the chart of the elements as that number increases. I.e. they say: “… our observation of such ostensibly strange behavior is still novel, since in stable nuclei, the attractive pairing interaction generally enhances the stability of "even–even" isotopes”… but this is, like the drip line itself, just an experimental observation which any theory developed in the future should explain.*

Despite the above and your article, I am still forced to continue to conclude that there must effectively be a net weak repulsion between two mutually near neutrons (when no protons are present as in Tritium & He) as they will not mutually bind, do not exist, cannot be created, even though the “strong force” is thought to act between neutrons, as it clearly does between a neutron and a proton (Deuterium, does stably exist.)

I have no idea what the nature of this neutron/neutron repulsive force could be (A fifth force of nature of limited range?). Despite it, if exists, I still see no need to change anything I said in post 410. If you think I said anything wrong in post 410, please tell what the error is specifically. I want to learn more nuclear physic as I know little in this field, but perhaps not much by way of nuclear binding theory is firmly known – only a lot of observations still waiting for a unifying theory.

As I stated earlier, I suspect part of the difficulty in understanding nuclear binding may be that the net force acting on a nucleon is NOT the sum of the individual forces. For example, perhaps the presence of a proton, kills the strong, short-range, repulsive force I postulate exists between two neutrons. That could explain why Deuterium, NP, is bound but NN is not even though in neither case is there any Coulomb repulsion and both do have the strong force binding. Also a short range repulsive force which dies with nearby charge present could also explain why more neutrons can not stably be added to the heaviest stable isotope - they, being on the "outside" of the more central cluster of N&Ps bound by strong force do not have their mutual NN repulsive force killed, so fly off - can not be bound to that most heavy stable isotope. I.e. why the "drip line" exists.

--------------------
* When I was a graduate student at JHU, I had some exposure to nuclear physics as JHU is (or was?) very strong in this area (one of the controlling managers of Brookhaven etc.) Even back then the stronger binding of the "even-even" isotopes was known.** In my quantum physic courses at JHU and earlier at Cornell in some very advanced courses which went into what was known about super conductivity the concept of "exchange energy" between two identical quantum particles was known and discussed. It shows up in their statistics - you can "exchange them", yet nothing is different after the exchange as they are indistinguishably identical so it is still the same state.

Dirac had an interesting idea as to why all electrons (and positrons, which could be considered as electrons traveling from the future to the pass) are identical - namely there is only one electron in the whole universe which has many scatterings in the past and in the future, but somewhere in the universe the positrons must dominate. I don't think he believed this was the case - just that it could explain why no electron is say 10% heaver or more charged than another - Another mystery of physics, still, I think.

** Some also suggested this stronger binding might be in some way be do to even-even isotopes being considered to be a collection of alpha particles.

[Read-Only]

Getting back to Rossi and his e-cat....

One thing I've found amusing ever since the start of this saga: Rossi has called all of his events "tests." No sincere inventor would have ever done that. They would have worked on the device in their garage, basement, at the university or wherever until they were satisfied the thing actually worked. Then, instead of tests they would have called the events demonstrations.

Apparently, few others caught that important bit of distinction. I make this point simply to underscore the fact Rossi was foolish UNLESS he was receiving external funding and needed something to show for his efforts and expenditure of someone else's money. HOWEVER, he claimed that he was providing all the funding himself.

So it's just another nail in his coffin as a hoaxer.

[kwhilborn]

Yes. He did call them demonstrations in his YouTube video back in January when it was first released. It is the public that has been calling them tests.

Even the wikipedia on ecat has a directory on "demonstrations", and none on "testing"

He did not have all the bugs worked out for his excess heat cannot be explained totally by him, and study is required according to him. However; he claims it can make electricity 30 times cheaper, and was worth bringing to market as is

@ billvon
a car that ran extremely cheaply (like 100 dollars per year) would be worth driving my current car into a lake on saved fuel costs alone. You obviously do not realize how small these units are and that steam could be converted into electricity. Nobody needs to drive a steam engine, and none of the alternate fuels you suggested are any cheaper. Electric cars mass produced no matter their size would be a lot cheaper than they are currently.

[Trippy]

Who have drawn the dark line on the chart of the nuclei shown in this figure from your link:
and called it the “drip line.” It has only an observational basis and could equally well have been called the “black line” or the “isotope boundary line” – just a name, explaining nothing, and certainly has nothing to do with anything “dripping.”

Not quite.

For starters, there are two nuclear drip lines - the proton drip line, and the neutron drip line.

And secondly:

However, an arbitrary combination of protons and neutrons does not necessarily yield a stable nucleus, and ultimately when continuing to add more of the same type of nucleons to a given nucleus, the newly formed nucleus will essentially undergo immediate decay where a nucleon of the same isospin quantum number (proton or neutron) is emitted; colloquially the nucleon has 'leaked' or 'dripped' out of the target nucleus, hence giving rise to the term "drip line". The nucleons drip out of such unstable nuclei for the same reason that water drips from a leaking faucet: the droplet, or nucleon in this case, sees a lower potential which is great enough to overcome surface tension in the case of water droplets, and the strong nuclear force in the case of proton emission or alpha decay.

Nuclear Drip Line on Wiki

It's probably also useful to note that early models of the atomic nucleus treated it as an incompressable fluid, which had some moderate success in predicting nuclear properties.
Liquid Drop Model on Wiki.

[Billy T]

To Trippy:

Thanks for explaining why called the "drip line."

What do you think of this paragraph which may not have been part of post 416 when you read it:

"... As I stated earlier, I suspect part of the difficulty in understanding nuclear binding may be that the net force acting on a nucleon is NOT the sum of the individual forces. For example, perhaps the presence of a proton, kills the strong, short-range, repulsive force I postulate exists between two neutrons. That could explain why Deuterium, NP, is bound but NN is not even though in neither case is there any Coulomb repulsion and both do have the strong force binding. Also a short range repulsive force which dies with nearby charge present could also explain why more neutrons can not stably be added to the heaviest stable isotope - they, being on the "outside" of the more central cluster of N&Ps bound by strong force do not have their mutual NN repulsive force killed, so fly off - can not be bound to that most heavy stable isotope. I.e. why the "drip line" exists. ..."

I sent it to Walter about an hour go by PM for his comments too. Of course it is just speculation, with zero evidence of being true but one has to start with speculative idea.

By the way: The liquid drop model was all the rage, when I had course in nuclear physics at JHU many years ago. In addition to what you mention, small impact parameter scattering experiments do give it some support too. I.e. nuclear radius /volume is consistent with an in compressible liquid model. - I don't follow the field but seems like the theorical advances are coming very slowly. - Is that your view too?