Review article on beam/accelerator driven fusion?

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Sven Andersson
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Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

You can accelerate nuclei of any light element and direct it to a target, that is usually solid. The first experiment of such a kind, was done with accelerated protons against a lithium target, I think. Thousands (or perhaps even tens of thousands) of such experiments have been done.

The result of the experiment is a curve of the number of fusion reactions (or the cross section of the reaction) as a function of energy of the incident particles.

I'm looking for some sort of review article on this. Or perhaps a monograph. Old or new doesn't matter.

This info may exist in data bases at IAEA's site, but how do you read them? I prefer to read what someone in the know, has written.
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Re: Review article on beam/accelerator driven fusion?

Post by Grigory_Heaton »

I use this, shown to me by someone on this forum a little while back:

https://www-nds.iaea.org/exfor/endf.htm

It's not perfect but it's the best I've seen so far. You can search for a given reaction (say for the 700 kV Cockcroft and Walton experiment you mentioned, you would do Target: Li-7, Reaction: p,g). My biggest issue with it is that almost all reactions except D,T and D,D have almost no data at energies less than 0.5 MeV. Once you search a reaction you can plot the data, usually cross section vs. energy.

Is that what you were looking for?
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Richard Hull
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Re: Review article on beam/accelerator driven fusion?

Post by Richard Hull »

Mark Oliphant is generally credited with discovering fusion via experiemnt in the 1932-33 time frame. Hahn and Strasserman discovered fission in 1938, again, by experiment.
Both Oliphant and Hahn-Strasserman failed to figure out what they had done or its ramifications. This is similar to Bequerel and Roentgen who made disoveries. They failed to fully appreciate or explain the physics behind what they discovered.

Lucky donkeys make discoveries.
Technology make those discoveries useful.
Physicists figure out the how and why of the mechanism, often long after the discovery and often long after technology has made the discoveries useful. (X-rays is a stunning example)

Some discoveries are figured out and developed rapidly via both physics and technology. (X-rays and fission)

Other disoveries languish once discovered and are fully explained and reproducible. Yet, they fail to develop a promise of major benefit to man (Fusion)

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

Grigory_Heaton wrote:Is that what you were looking for?
Not quite; I want the whole story. What happens at low energies is particularly important. I also have difficulties understanding that database. But, thanks for your reply anyway!
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

Richard Hull wrote:Mark Oliphant is generally credited with discovering fusion via experiemnt in the 1932-33 time frame.
The reason I pursue this is that I suspect that the nuclei, when they fuse in a beam fusion experiment are actually standing still relative to one another. The projectile nucleus gives up all or almost all of it's kinetic energy as bremsstrahlung. Then it is near the target nucleus and both are very close in both position space and momentum space and undergo nuclear fusion. How do you prove this? Measure the bremsstrahlung? Perhaps there are some clues in the graphs of cross sections plotted against kinetic energy?
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Re: Review article on beam/accelerator driven fusion?

Post by Grigory_Heaton »

Most reactions have no data at low energies because the output would be so tremendously low. Fusion is a tunneling process so it depends on particle energy and the width of the potential barrier. For example, proton-proton fusion could technically take place in water but the probability of this occurring at room temperature means that it is almost certain it has never happened in the history of the universe, and likely never will. Now something easier, for example p-B11 fusion at 3 keV, might technically be possible but would be essentially impossible to measure. That reactions just produces a bunch of alphas, so it would be incredibly difficult to see reactions if they are happening at an incredibly low rate. That's why you don't see a lot of low energy data there.


As for interpreting the graphs, cross section is the "area" of the target particle that can allow the reaction to take place. Think of it as probability. Higher cross section means better chance of fusion. So the cross section vs. energy chart just shows you what chance of fusion you can expect given a particle kinetic energy. To get a feel for what a certain cross section value "means", look at the successful fusion devices on this forum, find out what voltage they used, then use the equivelant electronvolt kinetic energy value and look at the cross section on the charts for D-D fusion.
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Re: Review article on beam/accelerator driven fusion?

Post by Dennis P Brown »

When you say
The projectile nucleus gives up all or almost all of it's kinetic energy as bremsstrahlung.
No, it doesn't. Nor do you really get what that process is if you think MeV protons just slow/stop because of a similar positive force.

Also, if a proton or other large nucli did what you said, then powerful gamma rays would be produced and seen with a characteristic spectrum that is easily identified - no such results, to my knowledge have ever been published and that would be an important discovery; so, no, unless you show otherwise, nuclei do not stop and fuse in that manner.

Further, in high speed fusion collisions do not need to tunnel since in the high MeV range, the Coulomb force can be over come so the strong force takes over leading to fusion.
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Re: Review article on beam/accelerator driven fusion?

Post by Richard Hull »

Yes, super high energy reactions don't need to tunnel, but at some point they kill fusion as well and head toward spallation. Ripping atoms apart without fusing at all. This depends on a number of factors. We fusioneers absolutely rely on Quantum Tunneling at our low energies. This yield abysmal results, but result quite usale and satisfactory to the amateur community.

The reason fusion cross section have a fall off at higher energies in collisions in low Z nuclei is due to spallation. D-D is a prime example. At about 1 mev in D-D fusion the Oppenheimer-Philips reaction starts to become favored. Neutrons are ripped from their deuterons with fusion falling off fast with increasing energy.

In the end, you can't win for losing.

Dennis is correct, if you fuse D-D in our two most favored reactions there are no photons due to bremsstralung during the act of fusion.... Maybe when the Tritons and Protons slam into the shell, yes, but not at the time of fusion.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

Dennis P Brown wrote:No, it doesn't. Nor do you really get what that process is if you think MeV protons just slow/stop because of a similar positive force.
If the projectile nucleus travels exactly on a trajectory that aims it towards a target nucleus, and if it has lost little or no kinetic energy from previous deflections, then the only outcome is that all or almost all of the kinetic energy is transformed into bremsstrahlung. Then the two nuclei both stand still and are very close to one another (the electrons that hold the crystal together are much further away) and fuse.
Dennis P Brown wrote:Also, if a proton or other large nucli did what you said, then powerful gamma rays would be produced and seen with a characteristic spectrum that is easily identified - no such results, to my knowledge have ever been published and that would be an important discovery; so, no, unless you show otherwise, nuclei do not stop and fuse in that manner.
Fusion in these beam fusion experiments is a rare event; about one projectile nucleus in 100 000 or one in a million or less fuse with a target nucleus. Meaning that the bremsstrahlung gamma rays produced are also rare and can be missed by investigators or confused with gamma rays from the fusion event itself. I'm sure that if a systematic search were made for this radiation then it would be detected. May have been mentioned en passant in some article sometime. Buried deep in the scientific/technical literature.

This is Charles S. Cagle's fusion, BTW.

http://adsabs.harvard.edu/abs/1990STIN...9113238B <---- Is this a book, or a data base or a report? How/where can I read it?
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Re: Review article on beam/accelerator driven fusion?

Post by John Futter »

Sven
I cannot think how you would measure your "gamma bremsstrahlung" in amonst a ton of x-ray bremsstrahlung as the detector cannot distinguish whether the energy recieved is gamma or x-ray
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Re: Review article on beam/accelerator driven fusion?

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Yes, trying to find out what was what in a hail of Xrays/gamma with its broad spectrum would be a nightmare. The fusor is actually a failed x-ray machine, unless you have a large glass view port. Its x-ray spectrum would be really wierd and contain, virtually, a zoo of energies. Naturally, the bulk of the x-ray flux, at our typically applied potentials, never exit the device.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Review article on beam/accelerator driven fusion?

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The amount of "proton" produced Bremsstrahlung is essentially zero in a fusor; this is due to the mass difference between electrons and protons. The average rate of electron Bremsstranhlung radiation is 10^13 greater (relative to power radiated) so then any radiation produced by a proton for any given energy - adding the fact that the electron velocities are many orders of magnitude greater than protons for a plasma (again, the mass difference) any such signal produced by a proton at fusor energies would further mean that such Bremsstrahlung radiation is again, essentially zero.

As for frequency of direct head on collisions between protons, this would not be a million to one (resulting in easily 10^16 such direct collisions in a fusor which would produce a huge signal) but, while I am not interested in doing the calculation, it is many orders of magnitude lower than that figure resulting in this, again, being an irrelevant occurrence so that no measurable signal for such an event is likely to be obtained.

Assuming that a collision process (where protons routinely are stopping in a fusor due to head to head collisions) is common and that proton in a fusor can create Bremsstrahlung radiation via interactions with other protons to create a viable signal to measure are, I feel, both inaccurate relative to what really occurs in a fusor and produces so few events as to be not realistic to be measured; these events are so rare as to be utterly irrelevant so I stand by my statements as accurate representations of what can and does not really occur in a fusor.
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

John Futter wrote:Sven
I cannot think how you would measure your "gamma bremsstrahlung" in amonst a ton of x-ray bremsstrahlung as the detector cannot distinguish whether the energy recieved is gamma or x-ray
It's a challenge, but I think it can be done. It requires, of course, a physics lab; it's nothing you can do at home. First thing you need is a gamma spectrometer. And a very carefully setup experiment, well shielded, from cosmic rays etc. Timing is important; the bremsstrahlung I hypothesize exists, should arrive at the detector, in advance of the gamma rays from the fusion itself.

Something that might be worth trying (to eliminate thermal motion) is to grow perfect crystals of Li-6 or Li-7 and the see what happens if you vary the angle of incident particles. If you experiment with Lithium, that is. Wait, a large, perfect crystal of Lithium-6 hydride (or Li-7), and then bombard it with protons at different angles.
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

Dennis P Brown wrote:The amount of "proton" produced Bremsstrahlung is essentially zero in a fusor;
The mechanism for fusion in a Fusor or a Tokamak is just that the fuel nuclei happen to be close in momentum space. This is Charles S. Cagle's mechanism for fusion. He removed his web-page, but you can find it in the link below. Fusion actually has nothing to do with banging nucleii into one another. Read the prophet Sir Charles! He knows everything.

http://web.archive.org/web/200008172348 ... tents.html
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Re: Review article on beam/accelerator driven fusion?

Post by David Kunkle »

I hope you're kidding? Spent some time looking at that site. I'm afraid Sir Charles scores awfully high on the 'ol index: http://math.ucr.edu/home/baez/crackpot.html
Commercially available fusion reactors that give off no harmful radiation by 2001? He's a little behind schedule.
If your experiment needs statistics, you ought to have done a better experiment.

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Re: Review article on beam/accelerator driven fusion?

Post by John Futter »

Sven
Yes you could grow di-lithium crystals and using an antimatter containment device get all that energy for your warp drive
(Ithink this was looked after by Scottie on the USS Enterprise)

PS I work in a nuclear Physics laboratory and what you want to do is not possible until a ready source of
high yielding flux capacitors is to be had ( all rights here to back to the future)
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Re: Review article on beam/accelerator driven fusion?

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I too, looked at the URL and the guy is kind of out there. There is a lot of self-proclaimed geniuses with new theories with no real proof or even experiment to back up their claims.
Just as there are many gurus there is also a cadre of enthralled followers for each guru. New energy and free energy sites abound with great promises and zero delivery. It is the nature of man to seek hope and the mission of these gurus to supply that hope.

This fellow's ideas are rather hollow and filled with holes and his efforts contain no real material results.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

John Futter wrote:PS I work in a nuclear Physics laboratory and what you want to do is not possible until a ready source of
high yielding flux capacitors is to be had ( all rights here to back to the future)
Flux capacitors?

What I claim is that towards the end of the tail of the bremsstrahlung continuum, there can be found traces of radiation that originates from the deceleration of the few nuclei that travel exactly towards a target nucleus. In your opinion, can this radiation be detected? What about my idea of detecting the time of arrival of the radiation?
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Re: Review article on beam/accelerator driven fusion?

Post by John Futter »

Ah yes
But when did it start
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

To Futter, Hull and Kunkle: dont write it off as nonsense until you can really be sure that it's nonsense! Cagle's physics that is.

In 1958 two swedish guys claimed that they had been in a fight with UFO-nauts that looked like grey dough. UFO-Sverige has written a long report on the case, many, many pages, interviewed witnesses and so forth. There is, of course no need for any investigation or action of any kind since everyone knows it's just nonsense. However don't write somebody's new physics off before you know for sure!

The great eye opener in my case was reading Cagle's theory on how a fusion bomb really works. Can be found in the part The Physics of Successfull Fusion.
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Re: Review article on beam/accelerator driven fusion?

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"Can be found in the part The Physics of Successfull Fusion." Already looked at that. The biggest things that are a red flag for me are:

One: He spends an awful lot of time trashing accepted physics and mainstream efforts at fusion for my taste. The difficulties and problems facing physics today are no secret- including the chasm between relativity and quantum mechanics. Trashing them infers those clowns are all barking up the wrong tree, but look at my great sounding theory- it must be right.

Two: Maybe if he spent as much time with details on his own theory, it would be a little more palatable. For proof, he claims a few experiments back up his theory- yet absolutely no details or references there! Apparently he has no experimental evidence of his own that any of his theory is sound either.

Three: Probably most important- the proof is always in the pudding. He hasn't so much as built a working prototype for proof of concept, yet he seems to have a sales pitch already. The reactors are completely scalable, completely safe (no radiation), have direct conversion to electricity and near 100% efficient, dirt cheap for the homeowner to purchase, and electricity from them will cost 1/800th of what the utilities are charging. And he has a cute name for it that's already trademarked. If that isn't putting the cart before the horse...I don't know what is.

He claims they will be for sale by 2001. And the copyright on the site is 1997; so 20 years have passed and still, apparently nothing so much as some experimental proof that there is something to his theories. Frankly, it all sends the needle high on my BS meter. The burden of proof is not on the skeptic, it is on those who would posit theories and make outrageous claims. I see nothing resembling proof in the entire site to think that he's onto something important- all indications point to the opposite.
If your experiment needs statistics, you ought to have done a better experiment.

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Re: Review article on beam/accelerator driven fusion?

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Sven Andersson wrote:The great eye opener in my case was reading Cagle's theory on how a fusion bomb really works. Can be found in the part The Physics of Successfull Fusion.
Below are two schematic drawings of H-bombs. In both of them can be seen a grey plate between primary and secondary. What's it for? It transforms gamma rays from the primary to soft X-rays. It is something like 10-15 centimeters thick and made of a high-Z element such as Uranium. It is immediately heated to millions of degrees and is then a completely dissociated plasma that is transparent to soft X-rays, because there are no ions, atoms or molecules in it to absorb such radiation. But there is an awful lot of electrons. They will undergo Compton scattering with the gamma rays from the A-bomb. The thickness of the plate is exactly designed, through simulation and calculation to produce, soft X-rays in the other end. In comes gamma rays and out comes soft X-rays. When they fall on the LiD, there will be a big boom.

Why is this info on the Internet? That is, the pictures I posted. The people who built or today maintain the bombs have such a hazy understanding of how the weapons work that they don't understand that the 'grey plate' is a great secret!
h-bomb.gif
schematic.gif
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Re: Review article on beam/accelerator driven fusion?

Post by Andrew Haynes »

@Sven Andersson
The U-238 taper is for shape charge, explosive wave propagation, the styform is the high cross section which turns to plasma, the U238 reflector is Pyrex
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Re: Review article on beam/accelerator driven fusion?

Post by Sven Andersson »

Andrew Haynes wrote:@Sven Andersson
The U-238 taper is for shape charge, explosive wave propagation, the styform is the high cross section which turns to plasma, the U238 reflector is Pyrex
The smokescreen is thick indeed, and won't be lifted anytime soon...
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Re: Review article on beam/accelerator driven fusion?

Post by Dennis P Brown »

I personally would prefer that these types of posts be avoided; wiki has all one needs to build real bombs in its far too accurate details and frankly, I find this stuff unprofessional to post here at a fun, educational fusor forum. Yes, my opinion and not policy in any manner here. But I feel that these types of posts tend to make the site look weapons related and such posts have absolutely no relevance to fusors. Certainly crackpot sites with their ludicrous claims on energy fusion does have a place to be discuses here but pulling in weapon related issues have zero relevance, in my opinion.
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