How a fusor works! Detailed theory

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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walter_b_marvin

Re: FAQ - How a fusor works! Theory

Post by walter_b_marvin »

Yes duty cycle frequency and wave form are all questions on resonance. On thinking about it what one really wants is a ping-pong paddle effect. A high enough potential to ionize virtually all the duterium between the meshes. Then a resting period to allow them to fuse, or miss each other and recombine. Then hit them again before they leak out of the outer mesh. This assumes the containment vessle is not the outer mesh. For a particular geomentry it should not be too hard to calculate a resonate frequency. Initially a square wave would be used. I expect a slightly larger than 50% duty cycle to do the ionization and push them beyond the inner electrode would be required. If the ions are accelerated to saay 10% of the speed of light, then they travel about 4 inches per nanosecond. So I expect the frequency to be several hundred Mhz to 1 GHz. Doesnt sound that practical at Kilovolt potentials.
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Re: FAQ - How a fusor works! Theory

Post by Sanchez-Yamagishi »

Just to point this out because it confused me, but the product energies for the DD reaction should be Mev, not mev. This probably would seem obvious to anybody who read it but just for those who are new to these conventions..

great read nonetheless though.

~Javier D Sanchez-Yamagishi
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Richard Hull
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Re: FAQ - How a fusor works! Theory

Post by Richard Hull »

I think all involved in this site know we are talking millions of electron volts in nuclear reactions and the M vs. m formality is often dropped of left uncorrected in the hast of battle in hammering out posts.

A lot of strict scientific formalism is often abandoned here. I am most often guilty of it. I know that it is 3He for helium 3, but always post it here as it is spoken ,"He3". We play over such a narrow field in these forums on amateur fusion that the lock step formalism is not enforced. Most anyone here would pick through any form of jumbles associated with a post and understand. Still, good habits here might save embarrasement before more august associations in future.

I would certainly use the formalism in any scientific paper or communication with a publication or such as that. I would also proof read the material more carefully than I do here.

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
DaveC
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Re: FAQ - How a fusor works! Theory

Post by DaveC »

In calculation velocities remember to use the ion mass, which is about 3700 times that of an electron. So speaking approximately, ion velocities are about 60 times smaller than electrons for the same energies. This gives a few MHz for frequencies.

A particular excitation frequency should tend to pick out a particular energy of ion. Thus tending to "bunch" or group ions . Whether this is beneficial to fusing efficiencies is hard to anticipate. But it is an interesting concept.

To Marvin's question, the potentials fall off as 1/r, which makes the fields vary approximately as (1/r)^2.

Dave Cooper
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Re: FAQ - How a fusor works! Theory

Post by Sanchez-Yamagishi »

Less trivial comment this time, something that has been bothering me for a while.

What are the energy ranges to cause D-D reaction to happen? Shouldn't it just be the energy necessary to overcome the Coulomb Potential to come within range of the strong force? So we have:

W = 1/(4*pi*epsilon) * (q^2 / r )

with r = 10e-15 m, the range of the strong force you get energies on the order of 1.4 Mev.

even if you ease up on r, because there is the possibility in D that they will collide with the neutrons facing each other so you have r = 3*10e-15 m you still get 0.5 MeV.

Given that the only thing driving the ions is the potential, the highest KE energy they can reach is the magnitude of the bias so how does fusion happen at anything less then 500 kV, let alone at a few kV.

I'm assuming the answer here will probably be through tunneling, I just haven't found it mentioned anywhere else though
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Richard Hull
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Re: FAQ - How a fusor works! Theory

Post by Richard Hull »

Quatum tunneling is indeed the fusion enabler at the lower kev levels. Actually, at levels approaching 2mev or more the oppenhiemer-phillips reaction takes over and fusion diminishes as deuteron "stripping" occurs more frequently than fusion.

So D-D fusion starts at a few tens of ev and continues up to well over 2 mev with the best fusing region occuring just around 1 mev. Oddly, there is little difference between 200kev and 1 mev based on the cross sectional curves.

In a well designed device using a very good, plus ultra neutron detection device it is easy to detect fusion at 10kev. At 20kev, even a poor neutron counter will indicate fusion. Easy to detect neutron activation experiments can be done in a fusor at 30-35kev applied.

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
Alex Aitken
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Re: FAQ - How a fusor works! Theory

Post by Alex Aitken »

In a pure deuterium plasma, fusion is a stripping reaction.

When a deuterium splits into a proton and a neutron at >2mev energies this is called 'break up'.

http://www.helsinki.fi/~fyl_www/common/ ... cla98.html

For an example of some other stripping reactions.
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Re: FAQ - How a fusor works! Theory

Post by MD1994 »

So from what I read it seems that the d ions will tend to return to there orginal positions and if thats 1.5 in away from the center of the inner grid orginally then if will return to 1.5 in away from the inner grid if it doesn't fuse. So wouldn't it be possible to use a a positive inner grid to repel ions and attarct electrons and ionizing them, but then could one change the inner grids charge to negative allowing all the ions that were formed in the walls of the fusor chamber to rush to the center and any of them that don't fuse couldn't they keep going to a distance equilvalent positions and since all the d ions were formed at that distance there wouldn't have been any d ions formed in the center that weren't accelerated and so they weren't fused. Of course you would have to do this I believe every time you put new deutrium gas into the chamber. But I just want to know if this is where they are born thing still applies in this situation, and if this will allow a greater number of d ions to fuse. Correct if I'm wrong which I probably am, sorry if I wasted anyone's time with this.
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Richard Hull
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Re: FAQ - How a fusor works! Theory

Post by Richard Hull »

In theory, in the simple fusor, and barring any collisions, an ion is doomed to perpetually circulate through a more of less central point in the device in an orbit with its starting point being where it is created. Thus, its energy can never exceed that of its relative creational, positional, acceleratory, fractional energy related to the potential difference between the outer wall and inner grid.

The above sad tale was in theory. However, in fact, it is usually even far worse than this already bad situation! Thus, we need hundreds of billions of ions created each second to get just a few tens of thousands to fuse. There are about (20!+6) valid scenarios of what can happen in a simple fusor to any one specific ion given an acceleratory potential of 40kv and an operational current 11.8ma when operated at something both above and below STP.

** Note: The (20!+6) factor shall henceforth be known as The "Hull ion life scenario factor for velocity space". This factor was carefully derived, metaphysically, while musing upon th' throne.

This is why it is called a simple fusor. Adding grids and thermionic cathodes can, again, in theory, aid the process by some factor, yet to be determined by any amateur.

Try your ideas and get back to us on how it worked out with full data and details versus your results using a simple fusor. Ideas need to be tested. Don't expect me to applaud or poo-poo your idea. A bit of "hands-on" will separate theory from actual experience. Pumping fusion up by novel ideas is possible by inch-worming degrees, but energetically useful fusion outside of a multi-mega-ton H bomb blast is currently impossible.

Wanna' destroy tens of thousands of lives? We've got your fusion solution.
Wanna' keep warm in the winter and watch some TV? Burn some coal.

You will not improve the simple fusor, save in microscopic steps. The more steps the more improvement and then the fusor will not be simple anymore, but become an evermore bloated, power hungry and complex megatherium of its former self.

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: FAQ - How a fusor works! Theory

Post by Richard Hull »

Pushed to the top of the pile as there is no FAQ banner or repository in this forum.

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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